Journal articles: 'Bauxite Diffraction'

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Cvetkovic, Zeljko, and Pavle Tancic. "Mineralogical and crystallographic characteristics of bauxites from some Grebnik’s (Metohija, Serbia) ore deposits." Annales g?ologiques de la Peninsule balkanique 80, no. 1 (2019): 45–61. http://dx.doi.org/10.2298/gabp19010045c.

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Five typical bauxite samples from three ore deposits from the wider area of Grebnik Mt. (Metohija, Serbia) were examined with the optical microscopic, X-ray powder diffraction (XRPD) and chemical methods. The occurrences in bauxites were studied and described and the presence of major minerals was determined: diaspore, boehmite and hematite; minor minerals: quartz, goethite, rutile, kaolinite and hydro-hematite; as well as anatase, brookite, magnetite and chromite, which occur only sporadically. According to the quantity of main Al-bearers, three types of bauxite ore were recognized: diaspore, boehmite and boehmite-diaspore. Unit cell dimensions of major minerals were determined, mostly with values within reference data. However, all of the studied hematites have smaller a0 and V0 values, most probably due to the substitution of Fe3+ by Al3+. All samples are further classified as iron-rich and ferritic bauxites. It was found that there were changes in origin conditions between major Al-hydroxides minerals and hematite, as well as between the diaspore and boehmite. Determined chemical compositions put this raw material into high-quality raw materials for obtaining the electro corundum and alumina. The synthesis of the obtained data indicate that Grebnik?s bauxites have some unique characteristics, more or less different from most of the World?s known bauxite ore deposits.

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Atakoglu, Ozge Ozer, and Mustafa Gurhan Yalcin. "Geochemical characterization of the Sutlegen bauxite deposit, SW Antalya." Mining of Mineral Deposits 15, no. 3 (September 2021): 108–21. http://dx.doi.org/10.33271/mining15.03.108.

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Purpose.The purpose is to determine geological and geochemical characteristics of the Sutlegen (Antalya, Turkey) bauxites, to identify the elements that played a major role in their formation. Methods. X-ray diffraction (XRD) mineral phase analysis, X-ray fluorescence (XRF) elemental analysis, plasma-mass spectrometry (ICP-MS), the petrographic and mineralogical analyses, and multivariate statistical methods were used. Findings. The major element content of the ore was determined as Al2O3 (60-35.2 wt%), SiO2 (39.5-0.2 wt%), Fe2O3 (48.4-19.5 wt%), TiO2 (36.9-16 wt%), and P2O5 (0.5-0.1 wt%). The Sutlegen region, which shows epirogenetic action with the uplift of the earth's crust, is generally rich in neritic carbonates. It was revealed that the bauxite ores have undergone moderate and strong laterization as a result of the deferruginization in the environment, and they were classified into four groups as lateritic, ferritic, kaolinitic, and bauxite. The increase in the aluminosilicate minerals, which were formed during the formation of bauxite in the environment was found to be directly proportional to the laterization processes. In this context, it was considered that the lateritic material that was firstly formed in the environment filled the cavities and pores of the karst-type limestones and sedimentary units in the region by superficial transfer phenomena. The bivariate diagrams of Log Cr vs. Log Ni revealed that the bauxite that formed in the region had an ultrabasic source. Originality. In literature, no scientific studies have been found on bauxite mineralization in the Sutlegen deposits that have been operated for a long period. Practical implications. In this context, the geochemical characteristics of bauxites revealed that the source of the laterization process in the region was the ultrabasic igneous rocks. The lateritic material moved by superficial transfer was accumulated on sandstone, claystone, siltstone, and limestone and in karstic cavities; then, it formed karstic bauxite (kaolinitic and bauxite) of different classifications due to the effect of metamorphism.

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Fang, Bin Zheng, Hui Li, Jian Wei Cao, Jian Feng Wu, Xiao Hong Xu, and Xi Dong Wang. "Structure and Performance of Calcined Bauxite." Advanced Materials Research 887-888 (February 2014): 305–8. http://dx.doi.org/10.4028/www.scientific.net/amr.887-888.305.

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In order to further broaden the application field of calcined bauxite, using differential thermal analysis-thermo-gravimetry (DTA-TG), X-ray diffraction analysis (XRD), Scanning electron microscopy (SEM) and other testing technology to study and analysis on the high temperature performance of calcined bauxite in this paper. The results show that the main crystal phases of calcined bauxite are corundum and mullite, appearance is layered, granular distribution. Due to the thermal performance of calcined bauxite is optimal, and is expected to be used for the field of high temperature solar thermal heat storage material.

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Melo, Caio C. A., Rômulo S. Angélica, and Simone P. A. Paz. "A Method for Quality Control of Bauxites: Case Study of Brazilian Bauxites Using PLSR on Transmission XRD Data." Minerals 11, no. 10 (September 28, 2021): 1054. http://dx.doi.org/10.3390/min11101054.

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Available Alumina (AvAl2O3) and Reactive Silica (RxSiO2), the main parameters of bauxite controlled in the beneficiation process are traditionally measured by laborious, expensive, and time-consuming wet chemistry methods. Alternative methods based on XRD analysis, capable to provide a reliable estimation of these parameters and valuable mineralogical information of the ore, are being studied. In this work, X-ray diffraction data in transmission mode was used to estimate AvAl2O3 and RxSiO2 from Brazilian bauxites using the Partial Least Square Regression (PLSR) statistical tool. The proposed method comprises a routine of sample classification according to their similarities by Principal Component Analysis (PCA) and K-means, calibration of the PLSR model for each group of samples, grouping new bauxite samples according to the generated clustering model, and subsequent estimation of the parameters AvAl2O3 and RxSiO2 using the PLSR models for these samples. The results showed good accuracy and precision of the models generated for samples of the main ore lithology. The quality and pre-processing of the XRD data required for this method are discussed. The results demonstrated that this method has the potential to be industrially applied to quality control of bauxites as a rapid and automated procedure.

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Nong, Liangqin, Xiying Yang, Lingmin Zeng, and Jingping Liu. "Qualitative and quantitative phase analyses of Pingguo bauxite mineral using X-ray powder diffraction and the Rietveld method." Powder Diffraction 22, no. 4 (December 2007): 300–302. http://dx.doi.org/10.1154/1.2790941.

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X-ray powder diffraction technique and the Rietveld refinement method have been used successfully for the qualitative and quantitative analyses of Pingguo bauxite from Guangxi, China. Qualitative phase analysis shows that the Pingguo bauxite contains diaspore (AlOOH), hematite (Fe2O3), goethite (FeOOH), anatase (TiO2), and kaolinite (Al2(Si2O5)(OH)4). Quantitative Rietveld refinement shows that the weight concentrations of diaspore, goethite, hematite, anatase, and kaolinite for the Pingguo bauxite are 71.9(4)%, 7.0(8)%, 11.3(7)%, 6.5(6)%, and 3.3(9)%, respectively.

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van Chanh, Nguyen, Mitsuhiro Shigeishi, and Tran Quoc Tho. "Inorganic Composite Material Based on Fly Ash, Red Residue from Bauxite Ore for Road Building Projects in Vietnam." Advanced Materials Research 383-390 (November 2011): 2774–81. http://dx.doi.org/10.4028/www.scientific.net/amr.383-390.2774.

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The paper present solidifying technology based on geopolymer theory of inorganic composite materials from bauxite, red residue from bauxite ore, fly ash and activators for road building projects in Vietnam. This study describes physical properties and chemical compositions of bauxite, red residue, fly ash and the effects of bauxite-red residue-fly ash-activator mixes on the geotechnical properties of inorganic composite materials. Mixture design and testing procedures for inorganic composite materials. New inorganic composite materials have high durability and ability to water resistance. The presentation also show microstructure analysis of inorganic composite materials based on bauxite residue, fly ash and activators by X-ray diffraction, Infrared spectroscopy (IR), transmission electron microscopy (TEM) display high density, and modified microstructure of inorganic composite materials. Construction method of road using inorganic composite materials is also presented.

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Jafar, N., S. R. Nurhawaisyah, S. Widodo, C. A. Chalik, and M. H. Wakila. "Mineralogical Study of Bauxite of Kenco Area, Landak District, West Kalimantan Province, Indonesia." IOP Conference Series: Earth and Environmental Science 1134, no. 1 (January 1, 2023): 012025. http://dx.doi.org/10.1088/1755-1315/1134/1/012025.

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Abstract Indonesia is a country with a tropical climate that allows for high levels of weathering. Bauxite is the result of weathering rocks that have high aluminum content, low iron content, and little quartz content. The formation of bauxite deposits is controlled by source rock which is rich in Al element, tropical climatic conditions, and geomorphological conditions that allow the formation of the accumulation of weathered source rock products. The altered silicate minerals due to weathering result in the silica element being released from the crystal bonds and some iron are released so that the aluminum element is concentrated as a residual precipitate. X-ray diffraction (XRD) analysis on 16 bauxite samples which are estimated to represent the overburden horizon, bauxite ore horizon, clay horizon, and source rock to establish the mineral composition of bauxite. Mineral groups in the overburden horizon, bauxite ore horizon, and clay horizon are alumina, iron, titanium, silicates, carbonates, sulfides, and sulfates, while mineral groups in source rock are iron, titanium, silicate, sulfide, and sulfate. The type of bauxite in the study area is gibbsite bauxite based on the dominant appearance frequency of gibbsite compared to mineral corundum as an alumina group.

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Yang, Fa, Bowen Guan, Jingyi Liu, Jiayu Wu, Jianan Liu, Chao Xie, and Rui Xiong. "An Investigation of the Polishing Behavior of Calcined Bauxite Aggregate." Coatings 9, no. 11 (November 15, 2019): 760. http://dx.doi.org/10.3390/coatings9110760.

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The application of top-grade calcined bauxite to improve the skid resistance of pavement surface coatings increases construction costs and causes excessive tire wear. Therefore, it is necessary to investigate the polishing behavior of different grades of calcined bauxite aggregate. The polished stone value of calcined bauxite was measured after the standard polishing time and the extended polishing time. The Los Angeles (L.A.) abrasion and the crushing value, profile roughness, hardness, X-ray diffraction, and micromorphology were also tested. The results showed that the calcined bauxite above 75# (the ratio of corundum to mullite by weight, C/M > 1) satisfied the requirement of the ultra-thin friction course. Compared with basalt, the calcined bauxite above 80# (C/M > 3) has better long-term skid resistance, even though the pavement surface is subject to heavier traffic. Due to the higher cohesion of lower porosity, more hard minerals to keep the surface roughness, and less soft minerals to smooth the surface roughness, calcined bauxite with a higher corundum content has the better skid resistance. There is a power law relationship between C/M and Polished Stone Value (PSV). Considering the diminishing returns of higher-grade calcined bauxite, it is necessary to accurately select the appropriate C/M of calcined bauxite before use in pavement surface coatings.

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Ma, Cong, Yuehu Tan, Erbing Li, Yinsuo Dai, and Meng Yang. "High-Performance Grouting Mortar Based on Mineral Admixtures." Advances in Materials Science and Engineering 2015 (2015): 1–11. http://dx.doi.org/10.1155/2015/425456.

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A study on high-performance grouting mortar is reported. The common mortar was modified by mineral admixtures such as gypsum, bauxite, and alunite. The effects of mineral admixtures on the fluidity, setting time, expansion, strength, and other properties of mortar were evaluated experimentally. The microstructure of the modified mortar was characterized by X-ray diffraction, scanning electron microscopy, and mercury intrusion porosimetry. Moreover, the expansive performance and strength of the grouting mortar were verified by anchor pullout test. The results show that the best conditions for gypsum-bauxite grouting mortar are as follows: a water-to-binder ratio of 0.3, a mineral admixture content of ~15%, and a molar ratioKof 2. The ultimate bearing capacity of the gypsum-bauxite grouting mortar anchor increased by 39.6% compared to the common mortar anchor. The gypsum-bauxite grouting mortar has good fluidity, quick-setting, microexpansion, early strength, and high strength performances.

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Dai, Yong-Ming, Cheng-Hsuan Hsieh, Jia-Hao Lin, Fu-Hsuan Chen, and Chiing-Chang Chen. "Biodiesel Production Using Bauxite in Low-Cost Solid Base Catalyst Precursors." Catalysts 9, no. 12 (December 13, 2019): 1064. http://dx.doi.org/10.3390/catal9121064.

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Investigation was conducted on bauxite mixed with Li2CO3 as alkali metal catalysts for biodiesel production. Bauxite contains a high percentage of Si and Al compounds among products. Because of the high expense of commercial materials (SiO2, Al2O3) that makes them not economical, the method was very recently improved by replacing commercial materials with Si and Al from bauxite. This is one of the easiest methods for preparing heterogeneous transesterification catalysts, through one-pot blending, grinding bauxite with Li2CO3, and heating at 800 °C for 4 h. The prepared solid-base alkali metal catalyst was characterized in terms of its physical and chemical properties using X-ray powder diffraction and field-emission scanning electron microscopy (FE-SEM). The optimal conditions for the transesterification procedure are to mix methanol oil by molar ratio 9:1, under 65 °C, with catalyst amount 3 wt.%. The procedure is suitable for transesterifying oil to fatty acid methyl ester in the 96% range.

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Zhang, Shangqing, Fenghua Zhao, Dongna Liu, Lei Zhao, Xiaohui Zhang, Junwei Lin, Haiyu Dong, Shuang Zhao, Xuefei Liu, and Minjie Zan. "Modes of Occurrence of Critical Metal Elements (Li, REEs and Other Critical Elements) in Low-Grade Bauxite from Southern Shanxi Province, China." Minerals 12, no. 8 (August 4, 2022): 990. http://dx.doi.org/10.3390/min12080990.

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The low-grade bauxite in southern Shanxi Province, China is enriched in multiple critical metal elements, including Li, Ga, V, Se, and rare earth elements (REEs), which have reached the standard of comprehensive utilization as independent deposits or associated resources. Even more importantly, identifying the modes of occurrence of these critical elements is essential for designing technologies to extract critical metals from bauxite ores. This study used a combination of direct (X-ray diffraction, scanning electron microscopy–energy dispersive X-ray spectroscopy, and micro-X-ray fluorescence spectrometer), and indirect (size sieving method, float-sink experiment, and correlation analysis) methods to effectively reveal the distribution of critical elements in the different identified mineral phases. The results regarding the low-grade bauxite are as follows: Li was mainly hosted in cookeite as an independent mineral; Ga was mainly associated with diaspore; anatase is the main carrier mineral for V; REEs were present in the low-grade bauxite in multiples modes of occurrence, the most common of which were goyazite, and to a lesser extent, florencite; Se primarily occurs in sulfides. This study contributes to the development and utilization of these essential metal resources in bauxite by providing a useful reference.

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Krysiak, Yaşar, Marcondes Costa, Herbert Pöllmann, Jürgen Göske, and Ute Kolb. "AUTOMATED ELECTRON DIFFRACTION TOMOGRAPHY ON NANOANATASE AND GOYAZITE FROM CLAY COVER OF BAUXITE DEPOSITS IN THE AMAZON." Boletim do Museu de Geociências da Amazônia 9, no. 1 (June 30, 2022): 1–15. http://dx.doi.org/10.31419/issn.2594-942x.v92022i1a2hmp.

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Since naturally occurring minerals typically have particle sizes from microns to several nanometers, their investigation, from sampling to individual particle analysis, is a challenging task. This work reports the detection of anatase, which occurs mainly in tropical soils and upon weathering in laterite. Little knowledge of this omnipresent accessory nanomineral, showing strong affinity to the soil formation processes and lateritic profiles is presently available. In bauxites the nano-anatase crystal morphology have not been reported yet. The samples were collected in a bauxite mine south of the Amazon (Juruti, Brazil). The chemical enrichment of anatase was carried out with H2TiF6 and the resulting powders could be characterized with SEM, XRPD and EDX. Subsequently, transmission electron microscopy (TEM) was used to analyze the chemical composition of individual anatase particles by EDX and the unique method of automated electron diffraction tomography (ADT), which probes the reciprocal space of individual nanoparticles. Associated with anatase, crandallite mineral group was also detected. Keywords: kaolinite; iron oxyhydroxides; gorceixite; goyazite; Juruti

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Nugraheni, R. D., C. P. Riyandhani, M. Apriniyadi, and D. Sunjaya. "Critical raw materials enrichment in bauxite laterite: a case study of diverse parent rock types." IOP Conference Series: Earth and Environmental Science 882, no. 1 (November 1, 2021): 012024. http://dx.doi.org/10.1088/1755-1315/882/1/012024.

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Abstract High demand in utilizing the mineral and metal for industrial manufacture, which is unequal to the resources, has caused a vulnerable disruption. To compensate stocks in the global market, exploration of raw materials should be carried out for by-products. This study aims to elucidate the enrichment mechanism of Sc, Ga, and Nb elements from the bauxite weathering profile and sediment residue. An observation has been conducted using petrography, mineragraphy, x-ray fluorescence spectroscopy (XRF), x-Ray diffraction (XRD), inductively coupled plasma combined with mass spectrometry (ICP-MS), and scanning electron microscope - energy dispersive spectrometry (SEM-EDS). The results indicate that bauxite ores (gibbsite) hold the metal compounds of Ga, while some iron minerals of goethite and hematite are present as Sc-bearing minerals, and Nb is highly concentrated within saprolite of bauxite. The maximum enrichment of Ga and Sc is observed from the bauxite sample and sediment residue derived from microdiorite pyroxene, which makes up 24.2 - 42.1 ppm and 39.9 - 55.4 ppm, respectively. By contrast, Nb enriched about nine-fold higher in the saprolite zone relative to bauxite produced by weathering of granitic parent rocks. It suggests that metal concentration in the lateritic products depending immensely on the precursor rock types.

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Cheng, Xiao Su, Ling Ke Zeng, Xiu Yan Li, Wen Yan Sheng, An Ze Shui, Ze Hao Liu, Ying Yuan Zhang, Yue Wang, and Yong Zhao Wang. "Preparation and Microstructure of Bauxite Ceramic Microsphere." Key Engineering Materials 336-338 (April 2007): 1124–26. http://dx.doi.org/10.4028/www.scientific.net/kem.336-338.1124.

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In this paper, microspheres were prepared by using Chinese bauxite as raw materials through centrifugal spray drying method. The microstructure and composition of ceramic microsphere were investigated by X-ray diffraction, scanning electron microscope and X-ray energy spectrum. The particle size was 10~100#m. The XRD analysis reveals that the main crystalline phase of the ceramic microsphere were α-Al2O3 and mullite (3Al2O3•2SiO2). The Al2O3 content (chemical composition) of the microspheres was little more than 70%, and the molar ratio of Al2O3/SiO2 was near to the molar ratio of alumina and silica of mullite.

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Shoppert, Andrei, Irina Loginova, Denis Rogozhnikov, Kirill Karimov, and Leonid Chaikin. "Increased As Adsorption on Maghemite-Containing Red Mud Prepared by the Alkali Fusion-Leaching Method." Minerals 9, no. 1 (January 20, 2019): 60. http://dx.doi.org/10.3390/min9010060.

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This study investigates the use of red muds as adsorbents for As (V) removal. Red mud is a waste that contains a large amount of iron oxides and hydroxides, which are excellent adsorbents of arsenic, especially those possessing magnetic properties and a large specific surface area. The purpose of the experiments was to study the possibility of obtaining an effective adsorbent by the direct extraction of alumina from bauxite using the caustic alkali fusion method and to compare the arsenic removal effectiveness and other properties of these red muds with industrial samples. Red muds were described using methods such as X-ray diffraction spectrometry (XRD), X-ray fluorescence spectrometry (XRF), SEM, vibrating sample magnetometry (VSM), and the Brunauer–Emmett–Teller (BET) method. The main iron-containing phase of the red muds obtained by fusing bauxite with caustic alkali is maghemite, which has a large specific surface area. The specific surface area of the obtained samples varied in the range of 6.1–54.9 m2/g. Arsenic adsorption experiments were carried out using five different types of red muds: industrial Bayer, industrial sintering, and red mud obtained through bauxite alkali fusion at 300, 500, and 700 °C. The red muds obtained by fusing bauxite with caustic alkali at 300 and 500 °C had the highest effectiveness removing arsenic; their As(V) uptake capacity was over 30 mg/g.

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Aylmore, Mark G., and Graham S. Walker. "The quantification of lateritic bauxite minerals using X-ray powder diffraction by the Rietveld method." Powder Diffraction 13, no. 3 (September 1998): 136–43. http://dx.doi.org/10.1017/s0885715600009982.

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The application of the Rietveld method to quantify mineral components of bauxite and lateritic samples was carried out in order to determine the ability of the method to obtain accurate mineralogical abundances for these materials. The method was initially applied to synthetic mixtures using both Cu and Co Kα radiations, and it was shown that Rietveld-derived data compared favourably with the weighed compositions. Application to two types of natural bauxite resulted in a high correlation between Rietveld predicted values and those calculated by proportioning peak intensities with chemical assays. The use of the whole pattern rather than selected peak intensities gives greater accuracy, confirmed by a strong correlation between derived oxide concentrations from XRF assays. Accuracy and precision were improved by the determination of isomorphous substitution of aluminum in goethite and hematite by refinement of unit cell dimensions. Importantly, the ability of the Rietveld program to successfully model several goethites with different levels of isomorphous substitution improved the correlation between predicted and calculated values. In addition, crystallinity and crystallite size that influence the reactivity of the mineral components can be derived from refined peak profiles.

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Feret, Frank R. "Selected applications of Rietveld-XRD analysis for raw materials of the aluminum industry." Powder Diffraction 28, no. 2 (May 2, 2013): 112–23. http://dx.doi.org/10.1017/s088571561300016x.

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In the last few decades, X-ray diffraction (XRD) systems have been paramount and irreplaceable in controlling bauxite exploration, as well as Bayer and reduction processes. XRD quantitative phase analysis in the aluminum industry witnessed a steady deployment of the Rietveld method, which at present progressively replaces existing methodologies in research and plant laboratories. Rietveld analysis not only helped to surpass traditional XRD calibration methods, it also opened the door for new applications previously not possible. The use of the Rietveld method to characterize selected materials unique to the aluminum industry, such as bauxite, red mud, and alumina is demonstrated and discussed. This paper also presents how synchrotron-based diffractograms obtained for bauxite and red mud samples allowed a much better understanding of mineralogical representation, and made it possible to leverage their Rietveld quantification. Despite clear advantages, the Rietveld method also has limitations that are revealed. For alumina phase quantification, a dedicated Rietveld analytical program was built with structure data for eight alumina mineralogical phases: alpha, beta (β-Al2O3 = Na2O•11Al2O3), delta, gamma (2), kappa, sigma, and theta. The paper gives unique examples of phase quantification in aluminas of various origins and phase composition.

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Gralik, G., A. L. Chinelattot, and A. S. A. Chinelatto. "Effect of different sources of alumina on the microstructure and mechanical properties of the triaxial porcelain." Cerâmica 60, no. 356 (December 2014): 471–81. http://dx.doi.org/10.1590/s0366-69132014000400004.

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Porcelains composed of kaolin-quartz-feldspar are called triaxial porcelains. The use of alumina as a substitute for quartz in porcelains has been developed for some time. The results show a significant improvement in their mechanical properties, but alumina has a high cost. The possibility of using alternative materials as a source of alumina with lower cost was investigated. In this work, alternative raw materials were used as a source of alumina: refractory bauxite, primary aluminum hydroxide, reprecipitated aluminum hydroxide. Compositions with commercial alumina and quartz were also formulated to better understand the effects of adding these alternative materials. The raw materials were milled, dried, and characterized by analysis of the particle size distribution, X-ray diffraction, and X-ray fluorescence. The compositions were formulated by replacing the different sources of alumina in the formulation of porcelain. The compositions studied were shaped by pressing and sintered at different temperatures (1150-1400 ºC). The results showed that the use of bauxite and aluminum hydroxide as an alternative source of Al2O3 is viable. The impurities contained in refractory bauxite contributed to the lower values of flexural strength found in compositions having refractory bauxite as a source of alumina. The compositions with reprecipitated aluminum hydroxide showed a high mechanical resistance at low sintering temperatures, while compositions with aluminum hydroxide obtained by the Bayer process achieved good results of mechanical strength in a wide temperature range.

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Aziz, Israa A., Moayyed G. Jalhoom, and Muhanad A. Kheriallah. "Extraction of Zirconium From Iraqi Bauxite Ore." Engineering and Technology Journal 38, no. 10A (October 25, 2020): 1421–29. http://dx.doi.org/10.30684/etj.v38i10a.523.

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This research is devoted to the study of the extraction of zirconium from Iraqi Bauxite Ore by using hydrometallurgical method. The chemical analysis was done to the bauxite ore by using X-ray florescence, X-ray diffraction and atomic absorption spectroscopy. Zirconium Extraction was performed via three stages; the first stage is leaching of bauxite with sodium hydroxide for alumina leaching. The second stage is leaching of zirconium species from the remained powder produced from stage one after washing with deionized water and, nitric acid (HNO3 solutions). The results of the first stage has reflected the recovery of 42.27 % of Al2O3 which has been leached 100°C temperature, 7.5 molar of NaOH, liquid to solid ratio of 20/1, and stirring rate 450 rpm. The highest leaching percent of zirconium (Zr%) from the red mud approached 98.48 % at 100°C temperature, 7 molar acid concentration, 120 min. contact time, solid to liquid ratio (S/L) of 16/1, and stirring rate of 450 rpm. 99.47% recovery of zirconium was accomplished from nitric acid solutions by use of 3molar tri-n-butylephosphate (TBP)in kerosene at ,contact time for 6 min, and organic to aqueous phase (O/A) of 4/1.

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Reddy, Tanguturi Ravindra, Krishnan Thyagarajan, Ovidio Almanza Montero, Sanapa Reddy Lakshmi Reddy, and Tamio Endo. "X-Ray Diffraction, Electron Paramagnetic Resonance and Optical Absorption Study of Bauxite." Journal of Minerals and Materials Characterization and Engineering 02, no. 02 (2014): 114–20. http://dx.doi.org/10.4236/jmmce.2014.22015.

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Gasparini, Arthur Stefanelli, Maurício Paulo Ferreira Fontes, Anderson Almeida Pacheco, and João Carlos Ker. "Gibbsite Crystallinity and Morphology in Ferralsols and Bauxites." Minerals 12, no. 11 (November 14, 2022): 1441. http://dx.doi.org/10.3390/min12111441.

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Gibbsite is a common mineral, present in several soil classes around the globe, especially in the tropical belt. It is also a key mineral in bauxite, the main natural source of aluminum. The occurrence of gibbsite in the soil greatly influences its physical and chemical characteristics. However, little is known about the important structural properties of this mineral, which determines how these characteristics will be expressed. In this work, we investigated the variation in the morphology and crystallinity of naturally occurring gibbsites from soils and bauxites. The crystallinity of the gibbsite was assessed using full width at half maximum (FWHM), mean crystallite dimensions (MCD), and deoxydylation temperature (DT) measurements. The results of these analyses were convergent, indicating a better crystallinity for gibbsites from the evaluated Amazon soils and bauxites, and worse crystallinity for the remaining soil samples. SEM analysis was used to assess the gibbsite morphology, and X-ray diffraction data were used to propose an orientation index for this mineral. The results indicated that there is little to no isomorphic substitution of Al by Fe in natural gibbsites, there is a prevalence of larger crystals, with a more laminar morphology, with orientation capability for the gibbsites of Amazon soils and bauxites, and smaller crystals tending to spherical shape for the other samples. These results suggest that natural gibbsite crystals of good crystallinity have large crystals with a laminar shape, while crystals of lower crystallinity present a smaller size and approximately an isodiametric shape.

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Negrão, Leonardo Boiadeiro Ayres, Herbert Pöllmann, and Tiago Kalil Cortinhas Alves. "Mineralogical Appraisal of Bauxite Overburdens from Brazil." Minerals 11, no. 7 (June 24, 2021): 677. http://dx.doi.org/10.3390/min11070677.

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Mineralogical appraisal is an important tool for both mining and industrial processes. X-ray powder diffraction analysis (XRPD) can deliver fast and reliable mineralogical quantification results to aid industrial processes and improve ore recoveries. Furthermore, X-ray fluorescence (XRF) chemical data, thermal analysis (TA), and Fourier-transformed infrared spectroscopy (FTIR) can be used to validate and refine XRPD results. Mineralogical assessment of non-traditional ores, such as mining wastes, is also an important step to consider them for near-future industries. In the Brazilian Amazon, alumina-rich clays cover the largest and most important bauxitic deposits of the region and have been considered as a possible raw material for the local cement and ceramic industry. In this work, a mineralogical evaluation of these clays (Belterra Clays) is performed using XRPD, XRF, TA, and FTIR. XRPD-Rietveld quantification confirmed that kaolinite is the main phase of the clay overburden, followed by variable contents of gibbsite and goethite and minor quantities of hematite, anatase, and quartz. The chemistry derived from Rietveld, based on stoichiometric phase compositions, presents a good correlation with the XRF data and is also supported by the TA and FTIR data. The initially assumed homogeneous composition of Belterra Clay is revealed to be variable by the present mineralogical study.

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Chaikin, Leonid, Andrei Shoppert, Dmitry Valeev, Irina Loginova, and Julia Napol’skikh. "Concentration of Rare Earth Elements (Sc, Y, La, Ce, Nd, Sm) in Bauxite Residue (Red Mud) Obtained by Water and Alkali Leaching of Bauxite Sintering Dust." Minerals 10, no. 6 (May 30, 2020): 500. http://dx.doi.org/10.3390/min10060500.

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One of the potential sources of rare-earth elements (REE) is the industrial waste known as red mud (bauxite residue), in which the majority of REE from the initial bauxite are concentrated via the Bayer process. Therefore, the studies of the subject, both in Russia and outside, focus almost exclusively on red mud processing. This article looks into the possibility of REE concentration into red mud by leaching an intermediate product of the bauxite sintering process at Russian alumina refineries, namely electrostatic precipitator (ESP) dust. The experimental works were performed by X-ray diffraction (XRD)and electron probe microanalysis (EPMA) of the sinter and sinter dust. The determination of major and rare-earth elements in the sinter from the rotary kilns and in the ESP dust before and after leaching was carried out by X-ray fluorescence (XRF) and plasma mass spectrometry (ICP-MS). The study showed that it is possible to obtain red mud that contains three times more REE than traditional waste red mud after two-stage leaching ESP dust in the water at 95 °C followed by leaching in an alkaline-aluminate liquor at 240 °C. The shrinking core model was used to study the kinetics of leaching of the original ESP dust and water-treated dust in alkaline-aluminate liquor. The study showed the change in the limiting stage of the alkaline leaching process after water treatment, with the activation energy growing from 24.98 to 33.19 kJ/mol.

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Bárdossy, György. "Scanning Electron Microscopic and X-ray Powder Diffraction Study of Manganiferous Bauxite, Kincsesbánya, Hungary." Clays and Clay Minerals 33, no. 6 (1985): 532–38. http://dx.doi.org/10.1346/ccmn.1985.0330608.

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Couperthwaite, Sara J., Sujung Han, Talitha Santini, Gurkiran Kaur, Dean W. Johnstone, Graeme J. Millar, and Ray L. Frost. "Bauxite residue neutralisation precipitate stability in acidic environments." Environmental Chemistry 10, no. 6 (2013): 455. http://dx.doi.org/10.1071/en13048.

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Environmental context Although land remediation programs for bauxite residues aim at vegetation coverage, the stability of compounds in the residues with acids produced by the vegetation has not been investigated. We show that, despite the instability of caustic components in the residues (negative effects on plant development), this instability actually assists in neutralising acidic soils. These results further affirm the suitability and sustainability of current land remediation programs for bauxite residues in terms of minimising acidic soil formation. Abstract This investigation used a combination of techniques, such as X-ray diffraction, inductively coupled plasma optical emission spectroscopy and infrared spectroscopy, to determine the dissolution mechanisms of the Bayer precipitate and the associated rate of dissolution in acetic, citric and oxalic acid environments. The Bayer precipitate is a mixture of hydrotalcite, calcium carbonate and sodium chloride that forms during the seawater neutralisation of Bayer liquors (waste residue of the alumina industry). The dissolution rate of a Bayer precipitate is found to be dependent on (1) the strength of the organic acid and (2) the number of donating H+ ions. The dissolution mechanism for a Bayer precipitate consists of several steps involving: (1) the dissolution of CaCO3, (2) formation of whewellite (calcium oxalate) when oxalic acid is used and (3) multiple dissolution steps for hydrotalcite that are highly dependent on the pH of solution. The decomposition of the Al–OH hydrotalcite layers resulted in the immediate formation of Al(OH)3, which is stable until the pH decreases below 5.5. This investigation has found that the Bayer precipitate is stable across a wide pH range in the presence of common organic acids found in the rhizosphere, and that initial decomposition steps are likely to be beneficial in supporting plant growth through the release of nutrients such as Ca2+ and Mg2+.

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Sun, Yong Qiang, Yong Li, Shuo Cao, Hao Bo Zhang, Chang He Gao, and Ji Li Zhang. "Research on High Temperature Creep Properties of Al₂O₃-SiO₂ Ore (Al₂O₃ ~ 65)." Key Engineering Materials 680 (February 2016): 343–46. http://dx.doi.org/10.4028/www.scientific.net/kem.680.343.

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High temperature creep properties of Al2O3-SiO2 ore (65% Al2O3 by mass percentage, abbreviation for Al2O3~65) was studied. The results show that the creep rates at 1300 °C × 50h, 1400 °C × 50h and 1500 °C × 50h were-0.89% ,- 1.75%, - 5.76%,respectively. At 1300 °C, ore has good creep resistance. As the temperature increases, the high temperature creep resistance of Al2O3 ~ 65 bauxite ore is significantly reduced. Creep process can be divided into two stages: when the time t <30h, the sample are in the densification process; after 30 hours, the creep properties show that the relationship between time and the creep rate is linear. At 1300 °C, the absolute value which is the slope of the linear relationship is smaller, exhibited an excellent high-temperature creep resistance. The loading softening-temperature of Al2O3 ~ 65 bauxite ore is 1343 °C. The Sample phase and microstructure are characterized by X-ray diffraction and scanning electron microscopy (SEM). The results show that mullite reticular is formed in sample at 1300 °C; at this point, TiO2 mostly exist as Rutile. At 1400 °C and 1500 °C, TiO2 mostly exist as Aluminum titanate, Corundum phase portion into mullite.

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Feret, Frank R., and Daniel Roy. "Determination of quartz in bauxite by a combined X-ray diffraction and X-ray fluorescence method." Spectrochimica Acta Part B: Atomic Spectroscopy 57, no. 3 (March 2002): 551–59. http://dx.doi.org/10.1016/s0584-8547(01)00408-6.

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Ramdhani, Eka Putra, Tri Wahyuni, Yatim Lailun Ni’mah, Suprapto Suprapto, and Didik Prasetyoko. "Extraction of Alumina from Red Mud for Synthesis of Mesoporous Alumina by Adding CTABr as Mesoporous Directing Agent." Indonesian Journal of Chemistry 18, no. 2 (May 30, 2018): 337. http://dx.doi.org/10.22146/ijc.25108.

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Mines in Bintan were producing bauxite for many years. The production process of bauxite to alumina produced much red mud. From X-ray Fluorescence (XRF), alumina content on Bintan’s red mud was 28.87 wt.%. This research was studying on the extraction alumina from red mud with reduction of hematite (Fe2O3) and desilication processes. After extraction process alumina was collected about 52.89 wt.%. Synthesis of mesoporous alumina from red mud using sol-gel method at the room temperature for 72 h with cetyltrimethylammonium bromide (CTABr) as mesoporous directing agent. The CTABr/Al-salt ratio, i.e. 1.57; 4.71 and 7.85 with the sample code of AMC-1, AMC-3, AMC-5, respectively. The product was calcined at 550 °C for 6 h. The synthesized materials were characterized by X-ray Diffraction (XRD), scanning electron microscopy-energy dispersive X-ray (SEM-EDX), transmission electron microscopy (TEM), and N2 adsorption-desorption techniques. XRD pattern of AMC-1, AMC-3, and AMC-5 showed that all synthesized materials have amorphous phase. The morphology were wormhole aggregate that were showed by SEM and TEM characterization. N2 adsorption-desorption characterization showed the distribution of pore size of about 3.2 nm. The highest surface area and pore volume were obtained in solid-solid ratio CTABr/GM-AL by 1.57 (AMC-1) i.e. 241 m2/g and 0.107 cm3/g, respectively.

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Kramar, S., L. Žibret, E. Fidanchevska, V. Jovanov, B. Angjusheva, and V. Ducman. "Use of fly ash and phosphogypsum for the synthesis of belite-sulfoaluminate clinker." Materiales de Construcción 69, no. 333 (February 8, 2019): 176. http://dx.doi.org/10.3989/mc.2019.11617.

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Fly ash and phosphogypsum were used as Naturally Occurring Radioactive Materials (NORM) by-products for the synthesis of belite-sulfoaluminate clinkers. The influence of raw mixture composition and firing temperature was investigated. Clinkers and cements were examined by X-ray powder diffraction and scanning electron microscopy with energy dispersive X-ray spectroscopy. The compressive strength of the cements was determined after 28 days. Clinker phases identified included ye’elimite, ß-phase of belite, ternesite and gehlenite, while the main hydration product of the cement pastes was ettringite. The results showed that belite-sulfoaluminate cements can be fabricated with a compressive strength of 45.9 N/mm2 by firing the raw mixture (70 wt.% marl, 10 wt.% bauxite and 20 wt.% phosphogypsum) at a temperature of 1320°C/1h.

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jun, Li, and Ju Yanmei. "Preparation of polymeric aluminum ferric sulphate from waste residue of aluminum industry." E3S Web of Conferences 271 (2021): 04005. http://dx.doi.org/10.1051/e3sconf/202127104005.

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Polymeric aluminum ferric sulphate(PAFS) was prepared from high-sulfur bauxite flotation tailings and red mud by roasting, acid leaching and polymerization. The effects of leaching temperature, leaching time, liquid-solid ratio on the leaching rate of Al3+ and Fe3+were investigated. The optimal leaching conditions are as follows: leaching temperature 100℃, leaching time 90 min, sulfuric acid concentration 4.5mol/L and liquid-solid ratio 5 mg/L. Infrared spectroscopy and X-ray diffraction analysis was carried out on the PAFS prepared under the optimum process parameters. The characterization of PAFS shows that the synthesized PAFS had polymeric aluminum, iron and hydroxyl structures. Wastewater disposal test of synthetic PAFS shows that the removal rates of COD, turbidity and chromaticity are 45.61%, 75% and 94.18%, respectively.

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Zhu, Yue Lin, Zeng Hua Chang, Juan Pang, and Chang Jian Xiong. "Synthesis of Zeolite 4A from Kaolin and Bauxite by Alkaline Fusion at Low Temperature." Materials Science Forum 685 (June 2011): 298–306. http://dx.doi.org/10.4028/www.scientific.net/msf.685.298.

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Zeolite 4A was synthesized by fusion method using kaolin and bauxite as raw materials. It comprised alkaline fusion followed by hydrothermal treatment with step-change of synthesis temperature. The synthesized zeolite 4A samples were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), and their calcium ion exchange capacity were tested by ethylene diamine tetraacetic acid (EDTA) volumetric method. The influence on the quality of zeolite 4A was investigated under different fusion temperature, fusion time, and mole ratio of SiO2/Al2O3, Na2O/SiO2and H2O/Na2O. The optimum reaction parameters were determined. The results showed that the reasonable fusion temperature and time should be 600°C and 2 h, and the reasonable ratios of raw materials were the SiO2/Al2O3ratios from 1.8 to 2.2, the Na2O/SiO2ratios from 2.0 to 2.3, and the H2O/Na2O ratio at 60, respectively.

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32

Kirwan, Luke J., Francis A. Deeney, Gerard M. Croke, and Kieran Hodnett. "Characterisation of various Jamaican bauxite ores by quantitative Rietveld X-ray powder diffraction and 57Fe Mössbauer spectroscopy." International Journal of Mineral Processing 91, no. 1-2 (April 2009): 14–18. http://dx.doi.org/10.1016/j.minpro.2008.11.001.

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Kar, Manish Kumar, and Jafar Safarian. "Characteristics of Bauxite Residue–Limestone Pellets as Feedstock for Fe and Al2O3 Recovery." Processes 11, no. 1 (January 3, 2023): 137. http://dx.doi.org/10.3390/pr11010137.

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Experimental research was carried out to produce pellets from bauxite residue for the further extraction of iron and alumina. Bauxite residue and limestone with three different mixture compositions were pelletized experimentally via agglomeration followed by drying and sintering at elevated temperatures. X-Ray diffraction (XRD) and scanning electron microscopy (SEM) were used for the phase and microstructural analysis, respectively. Tumble, abrasion, and breaking load tests were applied to determine the strength of the pellets. For measurement of porosity and surface area, mercury porosimetry and BET surface area methods were applied. It was found that at 1100 °C sintering temperature, all the three sintered pellet compositions have a moderate porosity and low strength, but the reverse result was found when 1200 °C sintering temperature was applied. Moreover, for the pellets sintered at 1150 °C high strength and proper porosities were obtained. In the sintered pellets, iron present in form of brownmillerite (Ca2Fe1.63Al0.36O5), srebrodolskite (Ca2Fe2O5), and fayalite (Fe2SiO4), while alumina present mostly in gehlenite (Ca2Al2SiO7) and little fraction in mayenite (Ca12Al14O33) and brownmillerite phases. The identified phases are the same for of the three pellets, however, with variations in their quantities. Porosity and mechanical properties of pellets are inversely related with both varying sintering temperature and composition. It was found that with more CaCO3 use in pelletizing, higher porosity is obtained. However, with increasing sintering temperature the strength of the pellets increases due to clustering of particles, while porosity decreases.

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Castaldi, Paola, Margherita Silvetti, Stefano Enzo, and Salvatore Deiana. "X-ray Diffraction and Thermal Analysis of Bauxite Ore-Processing Waste (Red Mud) Exchanged with Arsenate and Phosphate." Clays and Clay Minerals 59, no. 2 (April 1, 2011): 189–99. http://dx.doi.org/10.1346/ccmn.2011.0590207.

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35

Koštial, Pavel, Jozef Vlček, Zora Koštialová Jančíková, Hana Špačková, Jiří David, Robert Frischer, and Ivan Ružiak. "Effective Ecological and Cheap Heating of Dwelling Spaces." Sustainability 12, no. 1 (December 19, 2019): 55. http://dx.doi.org/10.3390/su12010055.

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The sustainability of human civilization depends largely on green energy management. This work represents one way to achieve this goal. The work is devoted to converting microwave radiation to heat. The article analyses different ways of heating residential and utility areas. Materials suitable for converting microwave radiation to heat from ceramic composites, concretes, fire clays, and bauxite with water glass are enclosed. For all materials we have measured DTA/TG (Differential Thermal Analysis/Thermogravimetric Analysis) curves, XRD (X-Ray Diffraction) patterns, chemical composition of samples, the specific heat capacity cp [J/kg.K], thermal conductivity k [W/m.K] and diffusivity α [m2/s-1]. The cooling curves of these materials after microwave heating are characterized in detail. The paper also presents a description and construction of a microwave reactor together with the parameters of the living space heating.

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Pereira, Carlos Eduardo, José Jailson Nicácio Alves, Romualdo Rodrigues Menezes, José Otávio Peroba Nascimento Santos, and Bianca Viana de Sousa. "Experimental Planning of Mixtures to Obtain Geopolymer." Materials Science Forum 798-799 (June 2014): 79–84. http://dx.doi.org/10.4028/www.scientific.net/msf.798-799.79.

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This work had the aim to optimize the synthesis process of a geopolymer using experimental planning of mixtures. The geopolymer was prepared with different proportions of bauxite mud (R), rice husk ash (C) and metakaolin (M). The aluminosilicatealkaline activation was made with sodium hydroxide (NaOH) solution of 12 mol/L. Afterwards, the obtained material was submitted through a thermal treatment for 6 hours in an oven followed by a cure time of 28 days at room temperature. The final material was characterized through combinations of different techniques such as Scanning Electron Microscopy (SEM) and X-Ray Diffraction. Through carefully analysis of the flexural strength results, it was possible to conclude that the geopolymeric material (R6C2M) had a greater resistance in the seventh cure day at 0.6 MPa, however, it also can be said that the other samples presented an increase in the resistance over the 28 days of cure time.

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Gonzalez-Triviño, I., J. Pascual-Cosp, B. Moreno, and M. Benítez-Guerrero. "Manufacture of ceramics with high mechanical properties from red mud and granite waste." Materiales de Construcción 69, no. 333 (January 28, 2019): 180. http://dx.doi.org/10.3989/mc.2019.03818.

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Red mud (bauxite residue) is an alkaline suspension that is the by-product of alumina production via the Bayer process. Its elevated annual production and the global inventory of red mud determine its valorisation. Granite can be used as a source of fluxing oxides for the ceramic industry, as can the flake-shaped waste generated during the flaming of granite. In this work, a set of ceramic pieces made of red mud and granite waste are prepared and characterised via X-ray diffraction, a hardness test, electron scanning microscopy, a leaching test, and determining open porosity, water absorption, bulk density and flexural strength of the samples. The main crystalline phases in the high-temperature fired products are hematite, pseudobrookite and anorthite; the presence of magnetite reveals their ferrimagnetic character. All samples present high mechanical properties. Leaching results are below critical levels established by regulations.

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Klárová, Miroslava, Jozef Vlček, Michaela Topinková, Jiří Burda, Alexandr Martaus, Ivan Priesol, and Jacek Szczerba. "Cement Substitution in High-Temperature Concrete." Minerals 11, no. 11 (October 21, 2021): 1161. http://dx.doi.org/10.3390/min11111161.

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An alternative binder to calcium aluminate cement (CAC) was prepared by the sol-gel method. Chemically pure systems such as tetraethylorthosilicate (SiC8H20O4) and nonahydrate of alumina nitrate (Al(NO3)3·9H2O) were used as major raw materials. The manufacturing process of binder via solution is mentioned, and transitions in binder structure as a function of thermal treatment in the range between 85 and 1400 °C are described. Finally, binder efficiency was verified by its application in high-temperature concrete instead of calcium aluminate cement (CAC). Newly developed sol-gel binder was characterized by XRFS quantitative analyses, XRD diffraction, STA-DTA and TG analyses and the BET method. Samples of concrete which were based on natural bauxite raw material showed cold compressive strength of 42 MPa compared to the same material where a conventional CAC was applied, and samples reached cold compressive strength of 44 MPa.

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Taylor, J. C. "Computer Programs for Standardless Quantitative Analysis of Minerals Using the Full Powder Diffraction Profile." Powder Diffraction 6, no. 1 (March 1991): 2–9. http://dx.doi.org/10.1017/s0885715600016778.

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AbstractA Fortran 77 computer program has been developed for the quantitative analysis of minerals by multiphase profile analysis of the complete powder diffraction pattern. Featured are full-matrix least-squares refinement of 14 Rietveld “instrumental parameters” (phase scales, asymmetry, preferred orientations (March model), linewidths, instrument zero, lineshapes and unit cell dimensions), Brindley particle absorption contrast factors and amorphicity corrections. The program uses a crystal structure Databank, which contains information on absorption coefficients, unit cell data and crystal structures for some 90 common minerals. New minerals can be easily added. Structure parameters are also refinable by a profile decomposition method using a program called STRUCT. The sum of the calculated patterns, derived from the crystal structure data, is fitted to the observed pattern by a program called TRACSCAL which runs in singlepass multiphase mode and, after the above corrections have been applied, the weight percentages of the component phases are calculated from the Rietveld scaling factors.The program runs on an IBM-compatible AT computer with 640K of RAM, on an extended memory AT, or a mainframe system. Examples of its use are given with standard mixtures and naturally occurring specimens. On an AT computer with 20MHz clock speed a scaling run, including data input, reading of the pattern, processing of (hkl) files, calculation of the profile and one cycle of least squares fitting takes about 30 seconds for binary standard mixtures and about 2.5 minutes for a 7-phase natural bauxite pattern containing 320 independent (hkl) reflections.

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Pereira, Carlos Eduardo, André Miranda da Silva, Josiele Souza Batista Santos, and Bianca Viana de Sousa. "Geopolymer Obtention Using Calcined Rice Husk Ash." Materials Science Forum 881 (November 2016): 373–78. http://dx.doi.org/10.4028/www.scientific.net/msf.881.373.

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This study aimed to synthesize geopolymer materials using the ash of burned rice husk. The material was prepared from bauxite slurry, rice hull ash was calcined at 600 °C, metakaolin and sodium hydroxide 12 M solution. The material was cured at 60 °C for 6 h and then at ambient temperature for up to 28 days. We used the same mixture of experimental design to synthesize geopolymer. Through techniques spectroscopy energy dispersive X rivers and X-ray diffraction, it appears that the silica and alumina contents of the identified raw material meets the conditions laid down as minimum for precursors with geopolymer activation potential, as evidenced by the molar ratio Si/Al sample. Geopolymer obtained from the XRD patterns showed characteristic peaks of hydrated calcium silicate. It was found that the particles had irregular shapes and sizes, and the presence of voids affecting the strength of the material. The geopolymeric material obtained showed improvements in the bending strength in a curing time of 28 days.

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Emerson, Thomas E., and Randall E. Hughes. "Figurines, Flint Clay Sourcing, the Ozark Highlands, and Cahokian Acquisition." American Antiquity 65, no. 1 (January 2000): 79–101. http://dx.doi.org/10.2307/2694809.

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AbstractAt the pinnacle of Eastern Woodlands’ prehistoric cultural development, Cahokia has been interpreted as a political and economic power participating in prestige-goods exchanges and trade networks stretching from the Great Plains to the South Atlantic. Among the more spectacular of the Cahokian elite artifacts were stone pipes and figurines made from a distinctive red stone previously identified as Arkansas bauxite. In this research, we used a combination of X-ray diffraction, sequential acid dissolution, and inductively coupled plasma analyses to establish the source of the raw material used in the manufacture of the red figurines and pipes that epitomize the Cahokian-style. Our research demonstrates that these objects were made of locally available flint clays. This finding, in conjunction with other evidence, indicate Cahokian exploitation of many mineral and stone resources focuses on the northern Ozark Highlands to the exclusion of other areas. These findings indicate that we must reassess the direction, extent, and role of Cahokian external contacts and trade in elite goods.

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42

Wang, Xiao Jing, Shu Feng Ye, H. W. Xu, L. Q. Wei, Xun Zhou, and Y. F. Chen. "Preparation and Characterization of the Decarbonization Preventing Nano-Coating Applied in Spring Steel Protection." Materials Science Forum 688 (June 2011): 238–44. http://dx.doi.org/10.4028/www.scientific.net/msf.688.238.

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Surface decarburization is one of important issues in spring steel production. The novel decarbonization-resistant nano-coating has been successfully fabricated, by using a low-cost, and easily accessible bauxite minerals and other additional components, including magnesia, silicon carbide，glass powder and agglomerant, which is used to prevent spring steels from being decarburized during the hot-rolling process. The microstructure of the protective nano-coating is observed by means of X-ray diffraction, TG-DTA, metalloscope and so on. It is found that even if some glass ceramic exists within the coating in the initial lower temperature (950°C~1000°C) the decarbonization-preventing coating still presents decarburization resistance up to 72.2%. Furthermore, the protective ration reaches to 100% when the heating temperature rises to range (1050°C~1100°C). The excellent decarbonization preventing properties are attributed to the formation of glass ceramic and pleonaste, which hinders the second interdiffusion of oxygen and carbon.

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Boquera, Laura, David Pons, Ana Inés Fernández, and Luisa F. Cabeza. "Characterization of Supplementary Cementitious Materials and Fibers to Be Implemented in High Temperature Concretes for Thermal Energy Storage (TES) Application." Energies 14, no. 16 (August 22, 2021): 5190. http://dx.doi.org/10.3390/en14165190.

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Six supplementary cementitious materials (SCMs) were identified to be incorporated in concrete exposed to high-temperature cycling conditions within the thermal energy storage literature. The selected SCMs are bauxite, chamotte, ground granulated blast furnace slag, iron silicate, silica fume, and steel slag. A microstructural characterization was carried out through an optical microscope, X-ray diffraction analysis, and FT-IR. Also, a pozzolanic test was performed to study the reaction of SCMs silico-aluminous components. The formation of calcium silica hydrate was observed in all SCMs pozzolanic test. Steel slag, iron silicate, and ground granulated blast furnace slag required further milling to enhance cement reaction. Moreover, the tensile strength of three fibers (polypropylene, steel, and glass fibers) was tested after exposure to an alkalinity environment at ambient temperature during one and three months. Results show an alkaline environment entails a tensile strength decrease in polypropylene and steel fibers, leading to corrosion in the later ones.

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Wahyinto, Indi Rizki, Anthoni B. Aritonang, and Titin Anita Zaharah. "Extraction and Characterization of Fe2O3 from Red Mud PT. Indonesia Chemical Alumina West Kalimantan." BERKALA SAINSTEK 10, no. 3 (October 4, 2022): 155. http://dx.doi.org/10.19184/bst.v10i3.30252.

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Red Mud is a term used for residues or waste materials from bauxite refining. One of the main compositions of red mud is Fe2O3. This study aims to obtain the optimum extraction of Fe2O3 conditions or hematite by using APDC ligands and knowing the characteristics of Fe2O3 generated. In this study, Fe2O3 extraction begins to determine the optimum pH and ligand concentration. The results of determining the optimum conditions showed pH 1 and ligand concentration of 0.5 M. Fe2O3 characteristics can be resolve through the characterization of Fourier Transformed Infra Red (FTIR), X-ray Diffraction (XRD) and X-ray Fluorescence (XRF). The results of FTIR characterization showed the stretching vibration of Fe-O Fe2O3 phase (570.50 cm-1 and 470.20 cm-1), XRD diffractogram showed the resulting crystal shape is rhombohedralsize is 27,08 nm, while the XRF characterization results showed the mass percent Fe2O3 before extraction is 42.48% and the mass percent Fe2O3 after extraction is 72.443%.

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Ferreira, M. C., Wilson Acchar, Ana M. Segadães, and Sonia Regina Homem de Mello-Castanho. "Second-Generation Aluminium Extraction Residue Used as Devitrification Aid for Glass-Ceramics." Materials Science Forum 587-588 (June 2008): 773–77. http://dx.doi.org/10.4028/www.scientific.net/msf.587-588.773.

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Brazil has one of the world’s most important Bauxite deposits, the raw material for the aluminium extraction metallurgy. This work is focused on finding a suitable application for the white dross residue (WDR), a second-generation waste material produced during the metal recovery from the slag left after the primary extraction of aluminium from the ore. A commercial lime-silica based glass frit was used, to which WDR additions were made (up to 30 wt.%), aimed at studying the devitrification process of the glasses produced. Such mixtures were melted at temperatures varying from 1100 to 1500°C and the resulting fritted glasses were heat treated at 900°C. The starting materials and the mixtures thereof were characterized before and after thermal treatment by differential thermal analysis, X-ray diffraction and fluorescence, and scanning electron microscopy. The results obtained showed that the WDR is easily incorporated into the glass matrix and causes easy devitrification after short heat treatment periods at low temperature.

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Gu, Xing Yong, Ping Li, Wei Xia Dong, and Ting Luo. "In Situ Formation of Mullite-Al₂O₃ Refractory Ceramic from Al-Matrix Mixtures." Key Engineering Materials 602-603 (March 2014): 628–31. http://dx.doi.org/10.4028/www.scientific.net/kem.602-603.628.

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Two types of mullite-Al2O3 composites were designed and sintered in situ from different composition containing Al composites e.g. kaolin, alumina hydroxide and calcined bauxite etc, and auxiliary additives. The phase composition and microstructure were studied using X-ray diffraction (XRD) and scanning electron microscope (SEM) techniques. Bulk density, apparent porosity, thermal expansion coefficient and bending strength were also measured. The two samples exhibited XRD reflections characteristic of alumina and mullite phases. The amount of these phases depended on starting batch compositions, and reaction of starting and auxiliary materials together to form mullite. Because of in-situ formation of mullite fiber, the bulk density and bending strength were improved and apparent porosity was decreased for the composites with uniform microstructure. The presence of high mullite phase was found to decrease the thermal expansion coefficient. The potential effect of these morphologies and phase on properties was discussed. These mullite-Al2O3 composite was expected to have major applications in the areas of refractory material.

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47

Yuan, Jingjiu, Chaoyi Chen, Junqi Li, Bianli Quan, Linzhu Wang, Yuanpei Lan, Xiaoqing Du, and Hui Fu. "Growth of corrosion product film on 12Cr1MoV steel in sulfur-containing sodium aluminate solution." Materials Express 9, no. 8 (November 1, 2019): 914–22. http://dx.doi.org/10.1166/mex.2019.1577.

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The growth mechanism of product film on steel surface in sulfur-containing sodium aluminate solution was studied with relevance to processing of high-sulfur bauxite ores in Bayer process. Scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), X-ray diffraction (XRD), potentiodynamic polarization curves and electrochemical impedance spectroscopy (EIS) were used to study the growth of corrosion product film on 12Cr1MoV steel in sodium aluminate solution containing 5 g/L S2– and 3 g/L S2O2– 3. Results indicated that the corrosion rate gradually decreased with increasing corrosion time (t). The fitted corrosion rate equation was V = 4.365t–0.809. The corrosion resistance was highest after 5 d. The growth evolution of the product film was divided into three stages: film formation, film conversion and film growth. The final corrosion product film comprised an inner film layer mainly composed of Fe3O4 and an outer film layer mainly composed of FeS, FeS2 and Fe2O3.

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Shoppert, Andrei, Irina Loginova, Julia Napol’skikh, Aleksey Kyrchikov, Leonid Chaikin, Denis Rogozhnikov, and Dmitry Valeev. "Selective Scandium (Sc) Extraction from Bauxite Residue (Red Mud) Obtained by Alkali Fusion-Leaching Method." Materials 15, no. 2 (January 7, 2022): 433. http://dx.doi.org/10.3390/ma15020433.

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Bauxite residue, known as “red mud,” is a potential raw material for extracting rare-earth elements (REEs). The main REEs (Sc, Y, La, Ce, Nd, Nb, and Sm) from the raw bauxite are concentrated in RM after the Bayer leaching process. The earlier worldwide studies were focused on the scandium (Sc) extraction from RM by concentrated acids to enhance the extraction degree. This leads to the dissolution of major oxides (Fe2O3 and Al2O3) from RM. This article studies the possibility of selective Sc extraction from alkali fusion red mud (RMF) by diluted nitric acid (HNO3) leaching at pH ≥ 2 to prevent co-dissolution of Fe2O3. RMF samples were analyzed by X-ray fluorescence spectrometry (XRF), X-ray diffraction (XRD), electron probe microanalysis (EPMA), and inductively coupled plasma mass spectrometry (ICP-MS). It was revealed that Sc concentration in RMF can reach up to 140–150 mg kg−1. Sc extraction was 71.2% at RMF leaching by HNO3 at pH 2 and 80 °C during 90 min. The leaching solution contained 8 mg L−1 Sc and a high amount of other REEs in the presence of relatively low concentrations of impurity elements such as Fe, Al, Ti, Ca, etc. The kinetic analysis of experimental data by the shrinking core model showed that Sc leaching process is limited by the interfacial diffusion and the diffusion through the product layer. The apparent activation energy (Ea) was 19.5 kJ/mol. The linear dependence of Sc extraction on magnesium (Mg) extraction was revealed. According to EPMA of RMF, Sc is associated with iron minerals rather than Mg. This allows us to conclude that Mg acts as a leaching agent for the extraction of Sc presented in the RMF in an ion-exchangeable phase.

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Su, Dunlei, Qiuyi Li, Yuanxin Guo, Gongbing Yue, and Liang Wang. "Effect of Residual CaSO4 in Clinker on Properties of High Belite Sulfoaluminate Cement Based on Solid Wastes." Materials 13, no. 2 (January 16, 2020): 429. http://dx.doi.org/10.3390/ma13020429.

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The high belite sulfoaluminate cement (HBSAC) containing CaSO4, and without CaSO4, based on solid wastes were successfully prepared from petroleum coke desulfurization slag (PCDS), fly ash (FA), carbide slag (CS), and bauxite (BX). The mineral composition of clinkers after different calcination history were investigated by X-ray fluorescence (XRF), X-ray diffraction (XRD)/Quantitative X-ray diffraction (QXRD), and scanning electron microscopy (SEM), so as to determine the calcination temperatures. The difference between residual CaSO4 and dihydrate gypsum (DG) and the optimal content of residual CaSO4 were discussed by studying the properties of HBSAC. The results revealed that the residual CaSO4 in clinker could replace DG to participate in hydration, and showed some advantages in strength and early hydration heat, but meanwhile increased the water requirement of normal consistency and hydration heat at 72 h, and prolonged the setting time. With the increase of residual CaSO4 content in clinker, the lower limit temperature of clinker formation gradually increased, and the crystal size of clinker minerals became finer and the boundary between crystals became more blurred. However, the optimal calcination temperature (1300 °C) of HBSAC clinker did not change. Considering the effect of residual CaSO4 content on the water requirement of normal consistency, setting time, hydration heat, strength, and hydration products, the optimal design content of residual CaSO4 in HBSAC clinker based on solid wastes, such as PCDS and FA, was 15%.

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50

Scarlett, Nicola V. Y., Ian C. Madsen, Lachlan M. D. Cranswick, Thaung Lwin, Edward Groleau, Gregory Stephenson, Mark Aylmore, and Nicki Agron-Olshina. "Outcomes of the International Union of Crystallography Commission on Powder Diffraction Round Robin on Quantitative Phase Analysis: samples 2, 3, 4, synthetic bauxite, natural granodiorite and pharmaceuticals." Journal of Applied Crystallography 35, no. 4 (July 18, 2002): 383–400. http://dx.doi.org/10.1107/s0021889802008798.

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The International Union of Crystallography (IUCr) Commission on Powder Diffraction (CPD) has sponsored a round robin on the determination of quantitative phase abundance from diffraction data. The aims of the round robin have been detailed by Madsenet al.[J. Appl. Cryst.(2001),34, 409–426]. In summary, they were (i) to document the methods and strategies commonly employed in quantitative phases analysis (QPA), especially those involving powder diffraction, (ii) to assess levels of accuracy, precision and lower limits of detection, (iii) to identify specific problem areas and develop practical solutions, (iv) to formulate recommended procedures for QPA using diffraction data, and (v) to create a standard set of samples for future reference. The first paper (Madsenet al., 2001) covered the results of sample 1 (a simple three-phase mixture of corundum, fluorite and zincite). The remaining samples used in the round robin covered a wide range of analytical complexity, and presented a series of different problems to the analysts. These problems included preferred orientation (sample 2), the analysis of amorphous content (sample 3), microabsorption (sample 4), complex synthetic and natural mineral suites, along with pharmaceutical mixtures with and without an amorphous component. This paper forms the second part of the round-robin study and reports the results of samples 2 (corundum, fluorite, zincite, brucite), 3 (corundum, fluorite, zincite, silica flour) and 4 (corundum, magnetite, zircon), synthetic bauxite, natural granodiorite and the synthetic pharmaceutical mixtures (mannitol, nizatidine, valine, sucrose, starch). The outcomes of this second part of the round robin support the findings of the initial study. The presence of increased analytical problems within these samples has only served to exacerbate the difficulties experienced by many operators with the sample 1 suite. The major difficulties are caused by lack of operator expertise, which becomes more apparent with these more complex samples. Some of these samples also introduced the requirement for skill and judgement in sample preparation techniques. This second part of the round robin concluded that the greatest physical obstacle to accurate QPA for X-ray based methods is the presence of absorption contrast between phases (microabsorption), which may prove to be insurmountable in some circumstances.

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Journal articles on the topic 'Bauxite Diffraction'

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