Добірка наукової літератури з теми "Lead smelter slag"

The study focuses on the reconstruction of the technological process in the 16th–17th century lead smelter in Sławków based on chemical and petrographic analyzes of slags. There are three main types of material at the landfill: glassy, crystalline, and weathered. Glassy slags are made of amorphous phase in which crystals of pyroxene, willemite, olivine, wüstite, and lead oxide appear. Crystalline slags are composed of wollastonite, rankinite, melilite, anorthite, quartz, and Fe oxides. Weathered slags have a composition similar to glassy slags, but they also contain secondary phases: anglesite and cerussite. Chemical analyzes confirmed that the smelter used sulphide ores, which were roasted, and the main addition to the charge was quartz sand. The smelting process took place in a brick-built furnace, under reducing conditions, with varied oxygen fugacity ranging from WM to MH buffer. The slag characteristics show a knowledge of the workers in the field of smelting methods. The addition of SiO2 allowed for the binding of elements that could contaminate the obtained lead, and at the same time, the low melting point of the material (1150 °C) and the melt viscosity (logη = 1.34 for 1150 °C) was maintained, enabling the effective separation of liquid lead.

Under the current pressure of mineral product price and market competition, as well as the tightening of ecological and environmental protection policies, energy saving, emission reduction and cost reduction, and efficiency increase have become inevitable trends. Lead-smelting slag of smelter, as an industrial byproduct, is harmful solid waste to be eliminated. In this research, a series of experiments on substitute for cement were done for filling cost reduction under premise of guaranteeing the filling strength, using PC32.5 cement as reference cementing material. Meanwhile, with Portland cement clinker, water quenching slag of BF ironmaking, and lead-smelting slag of smelter in different ratios, four cementing materials were made and named as cementing material I, cementing material II, cementing material III, and cementing material IV. Then, the above five cementing materials including PC32.5 cement were mixed, respectively, with tailing and water to prepare paste backfill slurry with different binder-tailing ratio and concentration. Backfill block was made and cured at 20°C; their uniaxial compressive strengths in different curing ages were measured. The result shows the strength of backfill test block using cementing material I (cement clinker and water quenching slag) without lead-smelting slag is far higher than that of test block using PC32.5 cement as cementing material. The strength of block with 16% lead-smelting slag increased dramatically, which was higher than the strength of block using PC32.5 as cementing material. However, the strength of test block decreased when the content of lead-smelting slag reached 32% and 40%. The more lead-smelting slag was added, the worse influence on strength of backfill would be. Because of large specific gravity of lead-smelting slag and low content of CaO, the hydration activity of lead-smelting slag is far lower than that of water quenching slag. Therefore, using moderate lead-smelting slag as substitute for cement will lead to increase of backfill strength and decrease filling cost.

AbstractLead, zinc and arsenic mobilization/attenuation processes during interactions between smelter slag and water show differences depending on the origin of the slag. The studied samples, waste from ore and car-battery processing, were submitted to long-term (365 days) batch leaching at two different initial pH values. The leachate analyses were input to the EQ3NR speciation-solubility code to speciate the solutions and determine the degree of saturation with respect to different phases, and a mineralogical investigation was made of the newly formed phases. An ‘oxidizing’ scenario can be proposed for slag waste disposal, considering that cerussite (PbCO3) at pH >6 becomes a major solubility-controlling phase for Pb, and newly formed hydrous ferric oxides (HFO – common secondary phases under oxidizing conditions) efficiently adsorb As. No efficient scavenging mechanism was found for Zn, which was progressively leached from the slag and in particular from the ore-processing slag. Quenched glass-rich slag from old car-battery processing was found to release significant amounts of Pb, especially in acidic environments. Neither slag would therefore be suitable for recycling for civil engineering purposes. Conversely, extremely low releases of Pb, Zn and As were observed for recent car-battery processing slag, which could therefore be considered for road construction.

This paper focuses on determining the feasible time for production of lead from spent paste (SP) by pyrometallurgical process through the rotary furnace. The extraction process faces several problems due to difficulties to control reaction media conditions. The experiments had been done on rotary furnace which exists in a secondary lead smelter in Baghdad - Khan Dhary. The SP mainly consists of lead sulfate and lead oxides. The experiments are implemented at high temperatures (1300°C) for reduction and desulfurization. 20 experiments were designed to determine the feasible smelting cycle time. The weight of slag, matte, and lead bullion was determined in each experiment as well as the percent of lead in each phase. These data were analyzed and graphically represented. The reaction’s rate profile can be detailed in the following manner: (1) High rate during the first 90 smelting min. Low rate from 90 to 120 min. Very low rate after 120 min. (2) The feasible extraction time is between 120 and 130 min with average lead percent in slag not >8%. (3) The slag with lead percent higher than 5% is returned to the furnace whereas the lower one is extracted by the blast furnace.

Relevance of the work. Wastes from mining and processing industries occupy vast areas and cause serious environmental damage. The research results will contribute to the development of biological reclamation of industrial areas and environmental monitoring. Purpose of the work: study of the geochemical features of soils and plants formed on old slags of the Polevsky copper smelter (Middle Urals). Methods of the study. We laid the plot in the relatively flat section of the base of the steep slope of the dump. Complex samples were taken at equal intervals on the transect and included blocks of technogenic soil along with growing plants. The material of the complex sample was divided into fractions by nature (soil, plants) and by size of fragments of copper smelting slag, dried to air-dry state and weighed. The chemical composition of the samples was determined by inductively coupled plasma mass spectrometry. Results. The man-made soil with a thickness of 10–15 cm has formed on the cast copper smelting slag old dump. More than a third of its mass is fine soil (particles less than 1 mm), which is a sorption geochemical barrier. The most elements concentration in fine soil is 1–2 orders of magnitude higher than their concentration in slag stone. Lead, cadmium, bismuth are especially effectively delayed. In the fine soil, the strongest excesses of the maximum permissible concentrations for all regulated elements have been established. It has been confirmed that under unlimited supply conditions of elements migration from slag, plant has an upper accumulation threshold. For the aboveground plant parts, the highest values of the biological absorption coefficient were found for selenium, potassium, calcium, and phosphorus. Conclusions. An environmental assessment of the Polevsky smelter (Middle Urals) old dump was carried out, the geochemical features of the soil and plants were investigated.

Annually, hundreds of thousands of tons of slags are involved in the reverberator and flash smelting as well as converting operations of Cu-Fe sulfide concentrates to produce matte in the Sar Cheshmeh copper smelter plant, Iran, disposed in the landfill and cooled in air. Due to their relatively high average copper content (about 1.5 wt%), a mineral processing plant based on the flotation process has recently been established to produce thousands of tons of Cu-sulfide concentrate after slag crushing and fine grinding operation. In order to make the flotation process more efficient, more knowledge is required on the form and origin of the copper losses in the slag. To achieve this, mineralogical studies of the slags using optical microscopy, X-ray diffraction (XRD), and scanning electron microscopy (SEM) methods have been carried out. Mineralogical analyses showed the main part of copper losses into the semi- to fully-crystallized magnetite-rich reverberator and flash slags characterized by crystal–glass matrix ratio ≤ 1 is moderate to coarse particles of Cu-Fe sulfides, i.e., chalcopyrite (CuFeS2) and bornite (Cu5FeS4), that are mainly chemically entrapped. In contrast, the mechanically entrapped fine- to coarse-grain (from 20 up to 200 µm) spherical-shaped of high-grade matte particles with chalcocite (Cu2S) composition containing droplets or veinlets of metallic copper (Cu0) are the dominant forms of copper losses into the converter slags characterized by crystal–glass matrix ratio > 1. From the value recovery point of view, our result show that the fully crystallized slags containing moderate- to coarse-grain copper-bearing particles will result in efficient recovery of a significant amount of entrained copper due to better milling response compared to semi-crystallized ones due to locking the fine- to moderate-grain copper particles in the silicate glassy matrix. Laboratory-scale grinding experiments showed that normal (≤74 μm) to fine (≤44 μm) grinding of high- Cu grade slags lead to a significant increase in the liberation degree of copper particles. in contrast, the increase in fine particle fractions (<37 μm) due to re-grinding or ultra-fine grinding of the originally low-Cu grade slags does not lead to the liberation of copper particles, but it will reduce the efficiency of the flotation process. This study suggests that the highest rate of copper recovery of the slag by the flotation process will be obtained at particle size 80% passing 44 µm which has also reached the optimal liberation degree of copper-bearing particles.

Alkali–activated aluminosilicates, known as geopolymers, have the potential to be used for sustainable concrete. Geopolymers encompass any binder systems derived from the reaction of an alkalis reagent with aluminosilicate rich materials that can harden at room (ambient) or elevated temperatures. The use of industrial waste materials in the manufacture of concrete not only introduces economic and structural performance benefits, but it also provides environmental benefits associated with reducing large volumes of disposed waste materials, such as ashes from coal–fired power stations and slags from metal production operations. Despite the commercial promise of geopolymer concrete technology, its widespread use is hindered by the lack of fundamental understanding of its potential long–term behaviour. Moreover, an understanding of the behaviour of reinforced geopolymer concrete, including the interaction between the reinforcement and surrounding concrete and its resistance to corrosion is sparse. This lack of information is significant, as it delays compliance with regulatory design standards and hence limits practical structural applications. This thesis explores the mechanical and structural characteristics of geopolymer concretes that are derived from class–F fly ash and granulated lead smelter slag. Significant aspects of these geopolymer concretes are investigated and the results are presented by compiling a series of journal papers. Firstly, mix designs utilising fly ash and lead smelter slags are developed and appropriate mix design guidelines are prescribed. For these mix designs, the material and mechanical properties of the concretes at both fresh and hardened states are then investigated. Having developed mix designs and quantified basic material behaviour, the long–term durability characteristics of both fly ash and lead smelter slag–based geopolymer concretes are extensively investigated. Particular attention is paid to the long–term durability of geopolymer concrete through consideration of the bond strengths of corroded and non–corroded steel reinforcement. The structural mechanisms related to the bond strength are investigated to quantify the formation of cracks, tension–stiffening and crack widening. Finally, the structural behaviour of granulated lead smelter slag–based geopolymer concrete short and slender columns was investigated through axial compression subjected to different eccentricities. From the investigation conducted in this thesis, it is shown that fly ash geopolymer concrete has comparable mechanical and structural behaviour to that of Ordinary Portland Cement (OPC) concrete. For a given compressive strength of concrete, the mechanical properties, durability, bond strength, tension–stiffening, and structural performance exhibited in geopolymer concrete are slightly higher than the corresponding measures of these properties in OPC concrete. Similarly, granulated lead smelter slag–based geopolymer concrete is shown to have potential as a cementitious material if the slag particles are crushed to a size similar to that of fly ash and OPC. Alternatively, granulated lead smelter slag is shown to be of use as a partial replacement for fly ash, which results in a blended binder. Significantly, based on the results obtained from this research, it can be stated that the current design provisions contained in the standards for Ordinary Portland Cement concrete can easily be modified and adopted for the applications of geopolymer concrete.
Thesis (Ph.D.) -- University of Adelaide, School of Civil, Environmental and Mining Engineering,2017

The developments of ordinary Portland cement (OPC) composites and alkali-activated binder composites have attracted significant attention in the past decade. Different technologies have been proposed to address current drawbacks of these construction materials (e.g. low tensile strength, flexural strength, and brittleness), reduce the amount of cement consumption or replace OPC products for minimizing the environmental impact of construction materials. Among many additives explored to address these problems, graphene-based materials have emerged in the last few years as one of the most promising additives with many exciting results. However, it is still lacking the depth of understanding the influence of key parameters of graphene materials, such as dosages and sizes, on mechanical and durability properties of the composites, and enhancing mechanism of pristine graphene (PRG) in the cement matrix. Moreover, no study has been reported on the influence of graphene oxide (GO) additives on mechanical and durability properties of fly ash (FA)/ ground granulated blast furnace slag (GGBS) alkali-activated binder (AAB) composites prepared with natural sand (NS) or lead smelter slag (LSS) sand cured at ambient temperature. This thesis consists of a series of studies with the focus on addressing current research gaps and making a contribution to the development of next-generation construction materials using graphene additives. The first experimental study on the effect of the dosage of an ultra-large size (56μm) of PRG industrially manufactured by an electrochemical process on compressive and tensile strengths of cement-based mortars reveals that the addition of PRG to mortars improves their mechanical properties, with characteristic concentration dependence. The mortar with 0.07% PRG is identified as the optimal concentration, which provides 34.3% and 26.9% improvement in compressive and tensile strength at 28 days, respectively. However, with the further increases in PRG contents, the enhancement of mechanical properties of mortars is limited due to the impact of the van der Waals force on the sedimentation of PRG suspension. The second study focuses on the size effect of PRG on mechanical strengths of cement-based mortars by considering a variety of PRG sizes, such as 5μm, 43μm, 56μm, and 73μm at the optimal dosage of 0.07% PRG. The study reveals that the mechanical strengths of mortars at 7 and 28 days significantly depend on the sizes of PRG. The mixes with size 56μm and 73μm show a significant influence on both the compressive and tensile strengths of mortars. In contrast, the mix containing size 43μm exhibits a significant increase in tensile strengths only. There are no significant effects on either compressive or tensile strengths for the mix with size 5μm. The third study presents the proposed reinforcing mechanism and optimized dosage of PRG for enhancing mechanical properties of cement-based mortars. The results confirmed that the strengths of the mortars depend on PRG dosages. The size of PRG has a significant effect on the enhancement rate of the mechanical strengths of the mortars, whereas it does not have a significant influence on the optimized PRG dosage for the mechanical strengths of the cement-based mortars. The dosage at 0.07% PRG is identified as the optimized concentration of PRG for enhancing mechanical strengths. The reinforcing mechanism of PRG in the cement matrix highly depends on the surface area of PRG sheets. The fourth and fifth studies show the effect of the dosages, sizes, and densities of PRG as well as design mixes on mechanical and durability properties of cement-based mortars cured at short-term and long-term periods. The study reveals that the addition of PRG to mortars can enhance compressive, flexural, and tensile strengths of mortars at different curing ages. The 0.07% PRG is identified as the optimum dosage for enhancing the mechanical strengths of the mortars. Incorporating a small amount of PRG additives into the mortar can improve its durability, such as water absorptions, voids, sulphate expansion, and water penetration depths. The results of the mix containing PRG size 73μm show the best improvement in the mechanical and durability properties of the mortars, followed by that of size 20μm and then size 40μm. The last experimental study on the influence of GO additive on mechanical and durability properties of AAB mortars containing NS and LSS sand cured at ambient temperature reveals that the increase of GGBS% in AAB results in a significant increase in compressive and tensile strengths, and a decrease in flowability, water absorption and dry shrinkage of the mortars. The results also show that the mortars with 0.05% and 0.1% GO additives provide better mechanical and durability properties compared to the control mixes. The results generated from this thesis show great potential for using PRG and GO as additives in OPC and AAB composites to develop next-generation construction materials. They not only address the current drawbacks of OPC and AAB composites but also reduce the environmental impact of using OPC and NS.
Thesis (Ph.D.) -- University of Adelaide, School of Civil, Environmental and Mining Engineering, 2020

Copper was the first metal used by humans, a practice that began at different times in various parts of the world. The earliest evidence comes from the Near East around 10,000 years ago, when some early farming communities started to experiment with surface finds of native copper. Initially collected for their golden colour, it was soon discovered that these small pieces of pure copper could be cold-hammered into desired shapes, making them different from rock minerals. This first occurred in areas such as northern Iraq and eastern Anatolia where native copper occurs naturally. By 7000 BC there is evidence from sites such as Cayönü in Anatolia for the heating of native copper (annealing) to improve the production of beads, awls, and other small objects (Muhly 1988, 1989). In time, this led to another important discovery, namely that native copper could be melted and poured into moulds at temperatures around 1083º C. It is not certain when this first occurred, but most probably in the sixth millennium BC (see Pernicka and Anthony 2010 for overview). One of the reasons for the slow development of metallurgy in the Near East was the scarcity of native copper. The growing interest in metal eventually led to experimentation with copper minerals, such as malachite or azurite (Wertime 1973). These were initially used for non-metallurgical purposes, with malachite beads dating to the eleventh millennium BC known from a number of sites, including Shanidar Cave in northern Iraq (Solecki 1969). They were first recognized during the search for native copper, when rock outcrops were discovered bearing the distinctive green or blue staining produced by oxidation of copper minerals. The extraction of these surface minerals must have led in some instances to underground mining. It is not certain when copper ore was first smelted in the Near East. The dating of copper smelting slag at Catal Höyük in south-central Anatolia to the seventh millennium BC remains contentious. The earliest secure evidence comes from the later fifth millennium BC, at sites such as Norsuntepe in southeast Anatolia and Abu Matar in the northern Negev, Israel (Pernicka 1990; Golden et al. 2001).

The paper presents studies of the processing of spent copper electrolyte from the processing of non-ferrous metal scrap at a copper smelter in Kazakhstan. For the processing of the spent electrolyte, a stage-by-stage neutralization was carried out using zinc sublimates and potash. As a result of the first stage of neutralization with zinc sublimations to pH 4.7, a precipitate with a content of PbO 44.69 %; PO2 16.36 % was obtained. After processing the sediment with an alkaline solution, carbonization and melting at a temperature of 900 oC, metallic lead and tin-containing slag with a content of SnO2 of 16.36 % were obtained. As a result of the second stage of neutralization with potash to pH 7.1, a precipitate was obtained-with a CuO content of 76.45 %. After the third stage of neutralization with potash to pH 9.5, a precipitate with a content of NiO 27.63 % and ZnO 55.75 % was obtained. After treatment of the precipitate with a solution containing 100 g / dm3 KOH, a zinc-containing solution with a ZnO content of 225.0 g/dm3 and a precipitate were obtained, after calcination of which nickel oxide with a NiO content of 89.14 % was obtained.