Phosphate Carbonated Wastes Used as Drains for Acidic Mine Drainage Passive Treatment

This study focused on the removal of heavy metals from a synthetic acid mine water by using continuous column experiments and Phosphate carbonated Wastes as alkaline drains. The passive treatment system targeted aims in neutralizing the acid mine drainage (AMD) containing high concentrations of dissolved iron and other metals. In Morocco, the phosphate mine industry produces huge quantities of overburden waste rocks (named herein PLW) which contain significant quantities of carbonates (calcite (46 wt %) and dolomite (16 wt %). The column experiments were set-up in laboratory and the testing were run under anoxic and oxic conditions by using a hydraulic retention time was 15 hours. The inflow to the treatment system ranged 5.5 mL/min, with acidic pHs of around 3, concentrations of dissolved Fe, Mn, Al, Ca, Zn and Cu were 600, 20,166, 350, 15 and 23 mg/L respectively, containing also some traces of Co, Cr and Ni. The test results showed that pH became neutral and a significant decrease in terms of metal concentrations; in particular for Fe (600 to 120 mg/L), Al (160 to 1.7 mg/L) and Cu (23 to 0.002 mg/L)

Valorization of Phosphate Waste Rocks and Sludge from the Moroccan Phosphate Mines: Challenges and Perspectives

Sedimentary phosphate mines produce millions of tons of waste rocks during their open-pit mining. In addition, during ore phosphate beneficiation, fluorapatite is separated from associated gangue minerals by a combination of successive mineral processing steps that involve crushing / screening, washing, and flotation. These operations generate large volume of tailings (called phosphate sludge) that are deposited in large surface ponds and waste rocks stockpiled within the mining site. The potential reuse of these phosphate mine by-products (waste rocks and sludge) has been investigated in the last 10 years. The first investigated option consisted in using the alkaline waste rocks (APW) to control the acid mine drainage (AMD). Indeed, these alkaline mine wastes contain significant quantities of calcite (46 wt%) and dolomite (16 wt%) that help in neutralizing the acidity generated by the wastes from the closed Kettara mine , located near Marrakech, Morocco. The addition of 15 wt% APW to the coarse Kettara tailings produced leachates with significantly lower acidity and metal loads in comparison to the unamended control sample. Secondly, the efficiency of APW was assessed in the laboratory as an alternative alkaline material for passive AMD water treatment. In semi-arid climate, the oxic passive treatment has been proven to be the most suitable. The pH of the water and its quality were significantly improved. As a third option, the hydrogeotechnical characterization of original and screened phosphate limestone waste rocks as well as the phosphate sludge showed their suitability for use as a component of store-and-release (SR) covers for industrial mine site reclamation. Lab tests (columns) and field tests (instrumented columns and experimental cells) showed that water infiltration can be controlled, even for extreme rainfall events (150 mm/day), by 1 m thick of a SR cover made with APW. Further research is currently being investigated around the recycling and valorization of phosphate sludge from phosphate mines as ceramics. Furthermore, the overburden of the phosphates sedimentary basins are mainly composed of marls; limestones blocks; silex bed; silex nodule; marls and clays; silicified limestone; which have a significant reuse potential as marble-mosaic floor, mortars and concrete, and natural stone products slabs for floors and stairs

Desulfurization of the Old Tailings at the Au-Ag-Cu Tiouit Mine (Anti-Atlas Morocco)

Tailings from the abandoned Tiouit mine site in Morocco are mainly composed of sulfides, hematite, and quartz. They contain 0.06–1.50 wt % sulfur, mostly in the form of pyrite, pyrrhotite, and chalcopyrite. The tailings also contain gold (3.36–5.00 ppm), silver (24–37 ppm), and copper (0.06–0.08 wt %). Flotation tests were conducted to reprocess the tailings for Au, Ag, and Cu recovery, and at the same time to prevent acid mine drainage (AMD) generation through the oxidation of sulfide minerals, including pyrite, sphalerite, arsenopyrite, chalcopyrite, galena. The flotation results confirmed that environmental desulfurization is effective at reducing the overall sulfide content in the tailings. The recovery of sulfides was between 69% and 75%, while Au recovery weight-yield was between 2.8% and 4.7%. The test that showed the best sulfur recovery rate and weight-yield was carried out with 100 g/t CuSO4 (sulfide activator) and 50 g/t of amyl xanthate (collector). The goal of this study was also to assess the remaining acid-generating potential (AP) and acid-neutralizing potential (NP) of the desulfurized tailing. The geochemical behavior of the initial tailings sample was compared to that of the desulfurized tailings using kinetic weathering cell tests. The leachates from the desulfurized tailings showed higher pH values than those from the initial tailings, which were clearly acid-generating. The residual acidity produced by the desulfurized tailings was most likely caused by the hydrolysis of Fe-oxyhydroxides

Sustainable reuse of coal mine waste : experimental and economic assessments for embankments and pavement layer applications in Morocco

This paper examines the potential reuse of coal mine waste rocks (CMWR) as an alternative material for road construction to conserve the natural resources and sustainable management of mining waste. The investigation was conducted through the determination of the chemical, mineralogical, geotechnical properties, and acid mine drainage formulation of CMWR as well as economic feasibility. An economic case study confirmed the workability of CMWR reuse in a radius of 29 km around their dumps. Results confirmed that weathered CMWR can be successfully used as a sustainable alternative material for creating embankments

Characterizations and Potential Recovery Pathways of Phosphate Mines Waste Rocks

The Phosphate Ore Production is Steadily Increasing Due to its High Demand for Agriculture, Medicine, and Others. Ore Extraction Generates a Considerable Quantity of Waste Rocks that Are Generally Stocked in Piles. the Current Research Aims to Investigate the Characterization of Phosphate Mine Waste Rocks (PMWR) Generated in Benguerir, Morocco Mine Site. as a Part of a Wide Project Aiming to Recycle Those Stockpiles, Sensor-Based Ore Sorting Will Be Employed to Separate the Different Lithologies. as a Prior Investigation Before Implementing This Technology, Two Samples of 25 Tons from the Destoning and Screening PMWR Piles Were Sampled and Submitted to Manual Sorting. the Latter Operation Revealed the Presence of Different Lithologies Including Indured Phosphate, Different Types of Siliceous, Carbonate, Phosphorus, and Marly Rock Types. Those Waste Rocks Were Characterized Physically, Chemically, and Mineralogically. their Potential Uses for Recycling or Upcycling Was Investigated and Addressed. About 25% of Indured Phosphate Was Found, Which Can Be First Recovered by Ore Sorting. This Reserve of Residual Phosphate Could Be Recovered using Beneficiation Methods. the Flintstone, Phosphated Flintstone, and Dolomitic Limestone Exhibit Good Physical and Mechanical Properties that Meet the Requirements to Produce Concrete. the Silexite and Siliceous Marls Have a Low Density and Could Be Used as Lightweight Aggregate for Non-Structural Concrete Blocks Production. the Investigation on Tender Marls Corroborates the Literature and their Suitability as Alternative Binders or as Supplementary Cementitious Materials. Those Marls Could Be Used as Well as Lime Binder for Repairing Historical Buildings or as Hydraulic Lime Binder for Road Construction. PMWR Valorization as Road Construction Materials Was Already Proved. However, Studying This Remediation Pathway after the Recovery of Phosphate and Other Lithologies by Ore Sorting is Highly Recommended. the Recycling of Those By-Products Will Decrease the Natural Resources Consumption in the Civil Engineering Field Alongside with Resolving their Environmental Problems

Récupération de l'argent des bains photographiques usés et élimination du cadmium des effluents cyanurés de traitement de surface par électrolyse et par flottation ionique

Not availableDeux nouvelles techniques sont étudiées pour récupérer l'argent à partir des bains photographiques usés et éliminer le cadmium contenu dans les eaux usées de rinçage de galvanoplastie. Il s'agit de l'électrolyse sur cathode volumique sous champ magnétique (électrolyseur REAM) et de la flottation ionique. L’étude du REAM a permis de conclure que l'application d'un champ magnétique à l'électrode volumique n'apporte quasiment aucune amélioration à la cinétique et au rendement d'épuisement de l'Ag et du Cd. Cet appareil se comporte donc comme un électrolyseur à électrode volumique classique. L’étude de la flottation ionique a montré que l'argent et le cadmium peuvent être extraits en utilisant comme collecteurs, respectivement, l'Aérophine 4818A et le dibromure de triphenylphosphonium-p-xylene (TPP^PX). Les rendements obtenus sont supérieurs à 97 %, pour une consommation en collecteur juste stœchiométrique. Les deux précipités obtenus flottent en moins de 5 mn, et titrent 34 % Ag et 12,4 % Cd. L'argent en présence du fer-EDTA est sélectivement précipité par l'aérophine, le solide obtenu est stable (pKs11,5). Le traitement thermique, à 900°C sous air de ce précipité, permet d'obtenir directement Ag métal (99,9%). Par ailleurs, après flottation, les bains photographiques épuisés en argent peuvent être recyclés. Le collecteur TPP^PX donne avec Cd(CN)2^4 un précipité stable (pKs9). L'élimination du cadmium par flottation ionique n'influe pas sur le pH et sur la concentration en cyanure libre de la solutio

Final technical report : management and stabilization of mining and industrial wastes (01/06/2009 - 1/06/2014)

When mines close, the health and environmental risks of mine waste depends on their acid generating potential. Abandoned mines containing reactive tailings are especially problematic. The project team investigates new technologies for the recycling and valorization of non-polluting mine wastes. In terms of training, Cadi Ayyad University in Morocco and Université du Québec en Abitibi en Témiscamingue (UQAT) collaborate to create high-quality training opportunities in the field of mining environment research. A significant outcome is the restoration of the abandoned Kettara mine site, which had been leaching heavy metals into the soil and water table for decades

Analyse de la décharge de déchets urbains de Marrakech relativement à l’évolution de la réglementation marocaine en matière d’environnement

For 11 years the city of Marrakech (Morocco) stockpiles his municipal solid wastes in an authorized landfill, the location of which was choosed from the criteria of urban planning and tourism. The analysis of the landfill according to the development of the environmental regulations in Morocco reveals two hazardous facts. The first fact is a great concentration of cupper and chromium in the landfill leachate explained by the wastes of cupper and leather from hand craft. The second fact is a risk that the wastes pile, estimated to a 0.6 MT weight and a 6 meter high, could slide because of the form of the landfill which is a slope bowl and due to an exceptionnal rainy event.La communauté urbaine de Marrakech stocke ses déchets dans une décharge autorisée depuis 11 ans dont le site a été retenu en fonction de critères d’urbanisme et de tourisme. L’analyse de la décharge en relation avec l’évolution de la réglementation marocaine en matière d’environnement montre premièrement que le lixiviat sortant de la décharge et allant vers l’oued Tensift est fortement charge en cuivre et chrome à cause des déchets de l’artisanat, deuxièmement que le tas de déchet dont la quantité est estimée à 0,6Mt, sur une hauteur pouvant atteindre 6 m et qui est stocke dans une cuvette inclinée, présente à terme un risque de glissement lors d’un évènement pluvieux exceptionnel

Recovery of Residual Silver-Bearing Minerals from Low-Grade Tailings by Froth Flotation: The Case of Zgounder Mine, Morocco

The need to explore more complex and low-grade silver ores and to develop novel and cost-effective processes to recover silver from waste is becoming an important challenge. This paper aims to characterize old, low-grade, silver tailings generated by the former Zgounder silver mine, located in Morocco. Understanding the mineralogical composition, particularly the silver deportment, was critical to allow the recovery of silver from these tailings. More than 88 samples of low grade tailings were sampled and characterized using chemical and mineralogical techniques. Froth flotation was used to recover silver bearing minerals using a combination of different collectors (dithiophosphate, dialkyl dithiophosphinates, Aero 7518, Aero 7640, alkyl dithiophosphates and potassium butyl-xanthate). The main goal was to optimize the flotation process at a laboratory scale through the testing of different parameters, such as collectors and frother types and dosage, activators and sulphidizing agents, and pH conditions. The characterization results showed that silver content varied between 30 and 440 ppm with an overall average content of 148 ppm. Silver occurs mainly in the form of native silver as well as in association with sulphides, such as acanthite and pyrite. Minor amounts of sphalerite, chalcopyrite, arsenopyrite, and hematite were identified. The flotation results showed the following optimum conditions: particle size of 63 µm, conditioning pH of 8.5, a combination of butyl-xanthate and dithiophosphate as collectors at a dosage of 80 g/t each, a concentration of 200 g/t of the activating agent (CuSO4), 30 g/t of methyl isobutyl carbonyl (MIBC) frother and a duration time of 8 min with slow kinetics. With these optimal conditions, it was possible to achieve a maximum silver recovery yield of 84% with 1745 ppm Ag grade to be cyanided. Moreover, the environmental behavior of the final clean tailings was demonstrated to be inert using Toxicity characteristic leaching procedure (TCLP) leaching tests