Academic literature on the topic 'Fluorapatite from Djebel Onk'

The production of phosphate concentrates is confronted with problems of treatment of wastes, of which the quantities are considerable. These wastes contain a large number of elements that are harmful to the environment. In this case, of phosphate wastes from Djebel Onk in the form of sludge that are the subject of our work, several trace elements have been recorded in limited levels. Indeed, elements such as lead and chromium have levels that exceed 60 and 300 ppm respectively. They far exceed the requirements of the mineral industry. The legislation, the severity of which varies from country to country, increasingly requires rigorous management and monitoring of these wastes in order to guarantee the protection of the environment from these toxic substances contained in the wastes. This work focuses on the management of phosphate wastes from Djebel Onk in liquid or sludge form. Current practices on their evacuation from neighbouring valleys to the operating site may harm the local environment. Moreover, the flow of this sludge which is increasingly thickened becomes more difficult. In this context, for environmental considerations and in order to define a concept linked to sustainable development, this study advocates a new approach in the recovery of phosphate wastes. It is based on the intrinsic properties of the present minerals determined by qualitative and quantitative analysis developed by different characterization techniques (XRD, XRF, IR, etc.). This makes it possible to define the chemical and mineralogical composition of liq- uid phosphate wastes which are rich in calcite (44.45 % in CaO) to those of phosphate elements (21 % in P2O5) and gangue minerals such as dolomite (7, 6 % in MgO), and quartz (5.8 % in SiO2). The microscopic observations carried out on these wastes showed the presence of the main minerals identified by XRD: fluorapatite, hydroxylapatite, carbonate, dolomite, calcite and quartz. The sought objective is to contribute to controlling these impurities to recover them from the water generated by the industrial installations for the exploitation of these materials with a view to their reuse in the laundries of the mining complex.

Phosphate rocks (PRs) play a crucial role in ensuring the availability of phosphorous for the world’s food needs. PRs are used to manufacture phosphoric acid in the wet process as well as P-fertilizers. The chemical and mineralogical compositions of PRs from Djebel Onk (Algeria), Khneifiss (Syria), Negev (Israel), Bou Craa (Morocco), and Khouribga (Morocco) are discussed in this study. PRs were characterized by inductively coupled plasma optical emission spectrometry (ICP-OES), cold vapor atomic absorption spectrometry (CVAAS), ion chromatography (IC), and X-ray diffraction (XRD), as well as gravimetric and potentiometric methods. All PRs were mainly composed of CaO, P2O5, SiO2, F, SO3, Na2O, MgO, Al2O3, Fe2O3, SrO, and K2O at the level of wt.%. The P2O5 content accounted for 28.7–31.2%, which indicates that these are beneficial rocks to a marketable product. The degree of PR purity expressed by the minor elements ratio index (MER index) varied from 2.46% to 10.4%, and the CaO/P2O5 weight ratio from 1.6 to 1.9. In addition, the occurrence of trace elements such as As, Cd, Cr, Cu, Hg, Mn, Ni, Pb, Ti, V, U, and Zn, as well as Cr(VI) and Cl ions at the level of mg∙kg−1 was found. Since PRs will be used to produce P-fertilizers, their composition was compared with the regulatory parameters set up by EU Regulation 2019/1009 related to the heavy metals (As, Cd, Pb, Ni, Hg, Cu, Zn) and Cr(VI) contents in inorganic fertilizers. The heavy metals and Cr(VI) content in all PRs did not exceed the limit values. XRD analysis revealed that fluorapatite, hydroxyapatite, carbonate fluorapatite, and carbonate hydroxyapatite were the dominant minerals. The accuracy and precision of the used methods were evaluated by analysis of standard reference materials (SRM) for Western Phosphate Rock (NIST 694). The recovery was 85.3% for U and 109% for K2O, and the RSD ranged from 0.67% to 12.8%.

This study is focused on the environmental geochemistry of potentially toxic metals (PTMs)-bearing products and wastes in a mining area in Djebel Onk (NE Algeria) and their potential ecological and health risk assessment. Representative samples from (i) commercial products and (ii) grain size classes of wastes were mineralogically characterized using X-ray diffraction. The major and PTMs elements in the samples were chemically analyzed via ICP-AES and ICP-MS, respectively. The results reveal that the samples were mostly composed of carbonate fluorapatite (P2O5 > 24 wt %) and yielded PTM concentrations within the average range of phosphorites in neighboring countries and worldwide deposits as well. The concentrations of V, Cd, As, Ni, and Pb in the products were found to be within the acceptable values according to various standards, such as the Canadian and German Fertilizer Ordinance policies. Geochemically, PTMs distribution is linked to the main sub-composition of phosphate rock (apatite, clay, and dolomite). The Enrichment Factors (EF) display very-high-to-extremely-high enrichment of PTMs (Cr, Zn, As, Sr, Mo, Cd, Sb, Tl, Th, and U), while V, Co, Cu, Ni, Zr, Ga, Nb, and Pb show minor and moderate-to-high enrichments. Among all the PTMs, Cd, Tl, and U display a very high ecological risk (PERI) and contribute most to the total risk index (RI). The human health risk assessment of PTMs represented by the Hazard Index (HI) indicates that the non-carcinogenic risks are below the threshold values (HI < 1), while the HI values are higher for children than they are for adults. However, the cancer index (life time cancer risk) for Cr, Ni, As, and Cd for children and Cd for adults is greater than the acceptable threshold. These results are useful for phosphate beneficiation via removing these PTMs from the commercial product for efficient waste management.

The objects of the research are phosphate ore rejections – industrial waste resulting from the treatment of phosphate ore by different processes (particle size separation, calcination, physicochemical process, electrostatically process, etc.). These discharges are generally stored in specially constructed sedimentation ponds. However, its storage for a long period leads to serious environmental problems because they contain heavy and radioactive metals that affect nearby communities. They contaminate groundwater and surface water through the infiltration of caustic solution laden with rare metals. To remedy these environmental disasters and manage these concerns, it is necessary to upgrade the discharges from the Djebel Onk complex and give an added value to the national economy. The start-up of the Djebel El Onk phosphate complex, in the province of Tebessa was in 1965, since that date, all the waste resulting from the beneficiation process has been dumped in the valley adjacent to the complex without any treatment or recycling, it should be noted that the Djebel Onk phosphate complex generates huge quantities of phosphate sludge (more than 4000 tons per day). This waste is relatively rich in useful substance. The results of chemical analyzes reveal that these sludge’s contain around 20.2 % of phosphate (P2O5) with the presence of different heavy metals such as Uranium, Cadmium, Zinc, Copper, and Arsenic etc. Those metals threaten life of local residents and affects vegetation, livestock in nearby populated areas. However, this work systematically reviews the mineralogical and chemical characterization of the phosphate sludge rejected by the Djebel Onk treatment complex to develop a suitable method for their revaluation. In our work, in this viable environmental perspective, we try to highlight the use of wastes as an alternative raw material in building materials. The impact of heavy metals on the environment and health is determined by the chemical species, concentration, bioavailability and transport through food chains, unless they are released into nature due to the consequences harm they create. Certain elements, such as mercury, lead, cadmium, zinc, copper, etc., have no function in maintaining body balance and are immediately dangerous.

Purpose. Valorization of phosphate waste and diversification of the range of bricks by improving their mechanical properties. In this context, our work focused on the use of phosphate wastes from Djebel Onk (Tebessa) combined with clays from the Sidi Aich region (Bejaia) to manufacture a new variety of brick. The principle consists in varying the percentage of these wastes and the firing temperature. Methodology. After mechanical preparation in the laboratory, which consists of crushing, grinding and sieving operations, the two materials of phosphate and clays are characterized by several analysis techniques (XRD, IR and XRF). The brick manufacturing tests from these two materials were carried out for different weight percentages and for different firing temperatures. Findings. The combination of these two materials constitutes a new approach to the recovery of natural phosphates, which has a very high waste rate. Tests of making bricks from these two materials have yielded promising results. From a mechanical point of view, the best flexural strengths obtained at a temperature of 900 C vary from 3 to 5 MPa depending on the type of phosphate/clay mixture. The same goes for the compressive strength, which varies from 15 to 27 MPa depending on the type of mixture as well. These results conform to ASTM-C674, 1999 construction standards. Originality. The use of natural phosphate wastes from Djebel Onk in various proportions has resulted in a quality of brick that meets the international standards. Practical value. The mechanical properties of the brick made from these two materials, such as resistance to bending and compression constitutes a real significant recovery for the phosphate wastes from Djebel Onk.

Research relevance. Phosphate mining activities are one of the main sources of contamination by heavy metals since they harmfully affect the soil and lead to the degradation of the ecosphere. Research aim. This study aims at characterizing and evaluating the metallic contamination of soils in the vicinity of the Djebel Onk mine in the town of Bir El Ater (Wilaya of Tébessa) in eastern Algeria, and particularly focusing on estimating the spatial variability of this contamination and the extent of the contaminated area. Methodology. The physicochemical characteristic (pH) was determined by pH-meter, whereas AAS was used for the determination of heavy metals (Pb, Cu, Zn, Cd) in the examined soil Research results. The results reveal that soils that are close to the mine site studied and even those that are far away are heavily contaminated with heavy metals — lead (Pb), zinc (Zn), copper (Cu) and cadmium (Cd); the results also point out to a high variability of concentrations not only between sampling sites but also within the same mine site. The analysed soil pollution index is generally high even for soils sampled downstream more than 30 km from the mine site, whereas it is extremely high on the surface of the tailings slopes, underlining the fact that tailings are considered perennial sources of heavy metal contamination in their current state. Conclusion. The unhealthy area affected by metal pollution from mining sites in the Djebel Onk is very large as a result of the dispersion, by wind and water transport, of residual pollutants from the mine wastes abandoned on site. Remediation measures must be put into place to immobilize the pollutants and limit their spread to the environment Keywords: Soil contamination, Algeria, heavy metals, phosphate mine, pollution index.

The aims of this paper was to evaluate the efficiency of phosphates product and by-products from the Djebel Onk mine for the control of acidic mine drainage generated by exposure of Sidi Kamber mine tailings to climatic conditions. Kinetic tests in humidity cells were carried out according to the modified ASTM standard, was used to invistigate the geochemical behaviour of the Sidi Kamber tailings mixed with phosphate materials (phosphatic limestone wastes, raw low grade phosphate ore and phosphate mine tailings) after being characterized. All amendment compositions led to an increase of the pH of the leachate from approximately 3 to circum-neutral values. Humidity cells experiments indicated that the materials were adequate to immobilize Pb, Zn, Cu and Fe by about 99% and prevent their release through the tailings. The tests have also shown that the metals concentrations within the leachate are lower than the limits allowed by Algerian legislation for industrial liquid effluents. Among the tested material amendments, PLW was more effective than other products in immobilizing metals. The results are most probably related to their Ca-carbonate content and/or adsorption capacity.

Cette thèse intègre le cadre général de la thématique de recherche scientifique du laboratoire d’hydrométallurgie et chimie inorganique moléculaire ex valorisation des minerais de l’USTHB. Le travail concerne la valorisation des éléments de terres rares lourds (ETRLs) contenus dans les ressources secondaires notamment les sous-produits miniers et les équipements électroniques en fin de vie par des procédés innovants et peu coûteux. Ce travail porte sur la faisabilité des techniques de séparation pour la valorisation des éléments de terres rares lourds (ETRLs) à partir d'un déchet industriel issu de l'exploitation des minerais de phosphate de "Djebel Onk" dans la région de Tébessa à l’Est de l’Algérie et les déchets électroniques après lixiviation menant à des solutions enrichies en éléments de terres rares suivie d’une extraction en utilisant des extractants organophosphorés et/ou des procédés membranaires. Des échantillons libellés de T1 jusqu’à T7 du minerai d'apatite provenant de Djebel Onk (Tébessa, Algérie) ont été fournis par la société Somiphos. D’après les analyses qui ont été effectuées sur tous les échantillons, l'échantillon T1 a été sélectionné dans cette étude car contenant la plus forte teneur en ETRs. Les résidus solides ont été d'abord lixiviés avec trois différents acides inorganiques (HNO3, H2SO4 et H3PO4) à des concentrations et des temps de lixiviation variés dans le but d’atteindre les paramètres optimaux. Les résultats des essais de lixiviation montrent un rendement très élevé d’ETRs avec l’acide HNO3 de concentration 3N durant 24h, ensuite une extraction liquide-liquide a été mise en œuvre avec deux exctactants TOPO et D2EHPA et des essais de micro flottaison en utilisant l’oléate de sodium et l’alkylhydroxylamine comme collecteurs dans différentes conditions. D’importants taux de récupération des phosphates ont été obtenus. Par ailleurs, une série de membranes ont été synthétisées ou modifiées (NF270, NF90, NP030 et SB90) dans la perspective d’être utilisées pour la séparation entre terres rares. Toutes les membranes élaborées ont été caractérisées. Les résultats obtenus permettent de proposer un protocole valorisant les ETRs contenus dans les ressources secondaires. La membrane NF90 modifiée par PEI/PDA pendant 48h a permis l’obtention des meilleurs rendements de purification
This thesis integrates the general framework of the scientific research theme of the laboratory of hydrometallurgy and molecular inorganic chemistry ex valorization of ores of the USTHB. The work concerns the valorization of heavy rare earth elements (HREE) contained in secondary resources, in particular mining by-products and end-of-life electronic equipment, by innovative and low-cost processes. This work deals with the feasibility of separation techniques for the recovery of heavy rare earth elements (HREE) from an industrial waste resulting from the exploitation of phosphate ores of "Djebel Onk" in the eastern region of Tebessa in Algeria and electronic waste after leaching leading to solutions enriched in rare earth elements followed by an extraction using organophosphorus extractants and/or membrane processes. Samples labelled T1 to T7 of apatite ore from Djebel Onk (Tébessa, Algeria) were provided by the company Somiphos. Based on the analyses that were performed on all samples, sample T1 was selected in this study as containing the highest content of REEs. The solid residues were first leached with three different inorganic acids (HNO3, H2SO4, and H3PO4) at various concentrations and leaching times in an attempt to achieve the optimal parameters. The results of the leaching tests show a very high yield of REEs with HNO3 acid of 3N concentration during 24h, then a liquid-liquid extraction was implemented with two exctactants TOPO and D2EHPA and micro flotation tests using sodium oleate and alkylhydroxylamine as collectors under different conditions. Significant phosphate recovery rates were obtained. In addition, a series of membranes were synthesized or modified (NF270, NF90, NP030 and SB90) with the prospect of being used for rare earth separation. All the elaborated membranes have been characterized. The results obtained allow us to propose a protocol to valorize the REEs contained in the secondary resources. The NF90 membrane modified by PEI/PDA for 48h allowed the best purification yields to be obtained