Polymetallic Tailings Research Articles

Leaching behavior of Cu, Zn, Fe and Pb from polymetallic tailings

ABSTRACT Copper tailings are a common byproduct of copper production, containing high levels of heavy metals which are released into the environment. Conventional methods have historically prioritized copper recovery, and often overlooking the leaching of other valuable elements. However, the rising demand for nonferrous metals necessitates understanding their leaching behavior from copper tailings. This study examined the atmospheric leaching of Cu, Fe, Pb, Zn, and CuO from a polymetallic tailing ore. Leaching recoveries of 63.5% for Cu, 97.5% for CuO, 1% for Fe, and 100% for Zn were achieved under the optimum conditions of 0.5 M sulfuric acid concentration, 25% solids percentage, 65°C, stirring speed of 100rpm, particle size of 75 µm within 30 minutes. Results indicated that the dissolution of oxide minerals such as CuO and ZnO was significant; however, copper sulfides need oxidant to be dissolved. In this condition, iron oxides and silicates were partially reacted by sulfuric acid, and Pb-bearing minerals formed lead sulfate. The presence of iron and lead-bearing minerals in the leaching residue was confirmed by XRF, XRD, and SEM analyses, and was in agreement with the information displayed in the Eh-pH diagrams.

Investigation of leaching of nickel sulfide flotation tailings to recover valuable metals

The global transition towards renewable energy, driven by low-carbon theories and technologies, has resulted in an increasing surge in the demand for critical and unique elements, of which nickel (Ni) and copper (Cu) are encompassed. In this investigation, using acid leaching, the recovery of such elements from polymetallic tailings to supplement conventional extraction processes was studied. The effective leaching parameters were investigated and optimized to enhance the simultaneous recovery of Ni, Cu, cobalt (Co), chromium (Cr), and manganese (Mn) from the tailings sample. To this end, the response surface methodology (RSM) was employed, with sulfuric acid (H2SO4) concentration (0–20 g/L), ethylenediaminetetraacetic acid (EDTA) concentration (0–20 g/L), ferric chloride (FeCl3) concentration (0–20 g/L), leaching temperature (20–80 °C), and leaching time (4–12 h) as independent variables. The analysis of variance depicted that ferric chloride concentration was the most prominent process parameter for the recovery of Ni, Cu, Co, and Mn. The recovery of Cr was contingent to leaching temperature and sulfuric acid addition. Ensuing tests under the optimal conditions resulted in the recovery of 100.0 % Cu, 89.8 % Co, 42.1 % Cr, and 100.0 % Mn in addition to 93.7 % Ni. The kinetics was also studied using the shrinking-core model. Kinetic data indicates that the dissolution of Ni, Cu, Co, and Cr is governed by the chemically controlled model, while that of Mn by the diffusion control model. The activation energies as per the Arrhenius equation are estimated as 32.43, 36.78, 34.88, 24.02, and 29.18 kJ/mol for Ni, Cu, Co, Cr and Mn.

Microbial adaptations and biogeochemical cycling of uranium in polymetallic tailings

Microorganisms inhabiting uranium (U)-rich environments have specific physiological and biochemical coping mechanisms to deal with U toxicity, and thereby play a crucial role in the U biogeochemical cycling as well as associated heavy metals. We investigated the diversity and functional capabilities of indigenous bacterial communities inhabiting historic U- and Rare-Earth-Elements-rich polymetallic tailings from the Mount Painter Inlier, Northern Flinders Ranges, South Australia. Bacterial diversity profiling identified Actinobacteria as the predominant phylum in all samples. GeoChip analyses revealed the presence of diverse functional genes associated with biogenic element cycling, metal homeostasis/resistance, stress response, and secondary metabolism. The high abundance of metal-resistance and stress-tolerance genes indicates the adaptation of bacterial communities to the “harsh” environmental (metal-rich and semi-arid) conditions of the Northern Flinders Ranges. Additionally, a viable bacterial consortium was enriched from polymetallic tailings. Laboratory experiments demonstrated that the consortium scrubbed uranyl from solution by precipitating a uranyl phosphate biomineral (chernikovite), thus contributing to U biogeochemical cycling. These specialised microbial communities reflect the high specificity of the mineralogy/geochemistry, and biogeography of these U-rich settings. This study provides the fundamental knowledge to develop future applications in securing long-term stability of polymetallic mine waste, and for reprocessing this “waste” to further extract critical minerals.

A combined compost, dolomite, and endophyte addition is more effective than single amendments for improving phytorestoration of metal contaminated mine tailings

Background and aimsRe-vegetation of mining-impacted landscapes reduces transport of toxic elements while improving soil fertility. This study evaluated whether the planting of a native perennial grass with a consortium of diazotrophic microbial endophytes and municipal waste compost—alone and in combination—enhanced plant growth while stabilizing metal(loids) in dolomite-amended tailings from a historically mined polymetallic mineral deposit.MethodsWe grew Bouteloua curtipendula seedlings in tailings with hazardous concentrations of As, Cd, Pb, Mn, and Zn. We evaluated how plant growth, organic matter accumulation, and major, minor, and trace element mobilization and phytostabilization responded to microbial endophyte and/or compost amendments after the 45-day growth experiment.ResultsAlthough most of the added endophytes were not uniquely identified, the best plant growth and fertility outcomes were achieved with a combination of amendments: dolomite to reduce acidity, compost to increase nitrogen, and a mixed consortium endophyte seed coating to synergistically increase organic carbon and grass biomass yields. Compost reduced shoot and root concentrations—but not yields—of contaminant metals. Endophytes increased foliar Cd, Co, Mn, and Pb yields but mobilized Pb and Zn from the tailings. Root stabilization of Cd, Co, Mn did not require amendments.ConclusionThe most effective means of revegetating these acidic, polymetallic tailings with the native B. curtipendula is with a simultaneous dolomite, compost, and endophyte seed treatment. Due to potential phosphate solubilization and siderophore production by this consortium of endophytes, strategies to capture solubilized metal(loids) may be needed for sulfidic tailings with metal(loids) associated with mobile mineral phases.

Tailings Utilization and Zinc Extraction Based on Mechanochemical Activation.

The significant containment of the global mining industry is caused by the problem of the transition to sustainable metal extraction and the integrated use of technogenic raw materials from the tailings of ore processing. The modeling of metal leaching processes using mechanical activation of polymetallic raw material components is particularly important in expanding the application of mining tailings as inert fillers of filling mixtures. This study is aimed at detecting the rotor speed factor on the chemical and mechanochemical effect of zinc yield growth from polymetallic tailings of the mining industry. In this regard, the purpose of this study was to improve the modeling of metal leaching processes using mechanical activation by improving the compositions of the filling mixtures. The methodology of the work included several comprehensive studies: the mechanical activation of tailings during zinc leaching from pulp in the DESI-11 disintegrator; the activation of enrichment tailings and the formation of a filling mass with different parameters of the component composition; the curing of cubic samples and their testing on the IP-1250 press. The Vi Improved text editor was used to prepare the algorithms for deterministic methods of three-dimensional interpolation in the Python language. The experimental results were graphically displayed using Gnuplot. The study of the agitation leaching of the waste obtained from the Sadonskiy mining district results in the fact that the NaCl mass concentration decreased from 13 to 1% and the H2SO4 concentration stabilization within 0.5 to 0.6% led to a 3-time increase in the zinc yield from the pulp, according to the polynomial law (from 28 to 91%). The obtained results expand the idea of the mechanism of the strength gain by the filling mass under mechanical activation on the components of the filling mixture, as well as changes in the efficiency of zinc leaching at different ratios of two types of lixiviants (sulphuric acid and sodium chloride) in the leaching solution.

Leaching characteristics and stabilization of heavy metals in tin-polymetallic tailings by sodium diethyl dithiocarbamate intercalated montmorillonite (DDTC-Mt)

There are a large number of tailings left over by industrial development the world over and the tailings are harmful to the environment for a long time, so it is very important to study how to reduce environmental pollution from tailings. Here, the acid producing potential of three types of tin polymetallic tailings from the same locality with different degrees of weathering and the forms of heavy metals that exist in these tailings were studied. The effects of pH of simulated acid rain, temperature and time on the leaching of heavy metals from the different tailings were investigated along with their leaching characteristics. In addition, stabilization mechanism of heavy metals was analyzed from the kinetic and microscopic aspects. The potential application of sodium diethyldithiocarbamate intercalated montmorillonite (DDTC-Mt) was studied for stabilizing tin polymetallic tailings. The leaching of heavy metals in tailings is mainly due to the oxidation of tailings, which in turn is closely related to the acid producing potential of tailings and the existing forms of heavy metals in them. The stabilization of heavy metals by DDTC-Mt is mainly due to coordination between DDTC and heavy metals in the interlayer of montmorillonite. DDTC-Mt revealed a superior stabilization property in remediation of heavy metals from tin-polymetallic tailings with high acid producing potential by enhancing the stability of heavy metals in tailings, for example, the stabilization rates of Mn and Zn were 89.11% and 93.89%, respectively.

Sulphate induced changes of rheological properties of cemented paste backfill

The rheological properties of cemented paste backfill (CPB) are important properties, which determine its flow ability or ease of transport in pipelines to fill underground voids. However, no research has been conducted to understand the effects of the sulphate content in CPB on its rheological properties, even though sulphate ions are usually found in CPB mixtures. Evaluating and understanding the effect of sulphate on the rheological properties of fresh CPB are important in carrying out backfilling with cemented paste. Therefore, the objective of this paper is to experimentally study the effects of the initial sulphate content on the rheological properties of CPB. Samples made with two different types of tailings (silica tailings and polymetallic tailings) with an initial sulphate content of 0, 5000, 15,000 and 25,000 ppm are prepared and cured at room temperature (20 °C). Their yield stress and apparent viscosity at different curing times of 0, 0.15, 1, 2, and 4 h are determined and then analyzed. Additional tests or measurements are carried out to further investigate the experimental results, which include monitoring through electrical conductivity (EC), measuring the pH and zeta potential as well as conducing thermal and XRD analyses. The results show that the initial sulphate concentration can significantly affect the rheological properties of CPB. The initial sulphate concentration can cause different microstructural or chemical changes in fresh CPB, such as inhibition of the cement hydration process or affecting the repulsive forces between particles. These changes significantly affect the yield stress and apparent viscosity of CPB. More specifically, the yield stress shows a trend of decline as the initial sulphate concentration is increased, while the apparent viscosity shows the opposite trend. The findings of this research demonstrate the significance of sulphate and its effects on the rheological behaviors or properties of CPB and can significantly contribute to the optimization of the transport of CPB through pipelines.

Naturally occurring radioactive material and risk assessment of tailings of polymetallic and Ra/U mines from legacy sites

Old mine tailings from Northern and Central Portugal were studied in order to perform a radiological and chemical characterization. The evaluation of massic activity of natural radionuclides and concentrations in tailings of polymetallic and Ra/U mines was performed by gamma spectrometry and neutron activation analysis. Iron speciation was carried out by Mössbauer spectroscopy. In polymetallic tailings with physical ore processing (Cumieira and Verdes - exploited for Sn, Nb-Ta) higher contents of Th, 228Ra and 226Ra in the coarser materials occur, probably due to their presence in host rock and ore fragments. In finer tailings, washing may explain the lower 226Ra and 210Pb massic activity. In tailings with physical/chemical ore processing (Covas - exploited for W and Sn) high U contents and a tendency for higher 226Ra and 210Pb massic activity in the fine materials is observed, probably due to their incorporation in nano-sized particles of iron oxides. A high variation of the 210Pb/226Ra ratio occurs in polymetallic tailings; a deficit of 210Pb can be observed particularly in deposits of settling tanks drained from dumps of chemically treated ore. In Ervideira-Mestras tailings (Ra/U exploitation) where no ore process in situ was performed, a near equilibrium between 210Pb and 226Ra occurs. Dose risk assessment was carried out by calculating external outdoor Annual Effective Dose Rate; the dose rates in air due to terrestrial gamma radiation are low for the polymetallic tailings (<47 nGy/h), and higher for tailings of Ra/U (up to 4130 nGy/h), in the worst scenario.

Review of Biohydrometallurgical Metals Extraction from Polymetallic Mineral Resources

This review has as its underlying premise the need to become proficient in delivering a suite of element or metal products from polymetallic ores to avoid the predicted exhaustion of key metals in demand in technological societies. Many technologies, proven or still to be developed, will assist in meeting the demands of the next generation for trace and rare metals, potentially including the broader application of biohydrometallurgy for the extraction of multiple metals from low-grade and complex ores. Developed biotechnologies that could be applied are briefly reviewed and some of the difficulties to be overcome highlighted. Examples of the bioleaching of polymetallic mineral resources using different combinations of those technologies are described for polymetallic sulfide concentrates, low-grade sulfide and oxidised ores. Three areas for further research are: (i) the development of sophisticated continuous vat bioreactors with additional controls; (ii) in situ and in stope bioleaching and the need to solve problems associated with microbial activity in that scenario; and (iii) the exploitation of sulfur-oxidising microorganisms that, under specific anaerobic leaching conditions, reduce and solubilise refractory iron(III) or manganese(IV) compounds containing multiple elements. Finally, with the successful applications of stirred tank bioleaching to a polymetallic tailings dump and heap bioleaching to a polymetallic black schist ore, there is no reason why those proven technologies should not be more widely applied.

Preparation of Ca-Substituted α-Sialon Eco-Materials by Utilizing Tungsten Molybdenum Bismuth Polymetallic Tailings

This presented a route to utilize the Tungsten Molybdenum Bismuth Polymetallic Tailings in Shizhuyuan of Hunan province to fabricate Ca-substitued α-Sialon eco-materials. The reaction mechanism in carbothermal reduction nitridation process was widely studied by separately considering the effect of sintering temperature and soaking time. Based on the optimized conditions, a composite containing 78% Ca-based α-Sialon has been fabricated at 1600°C for 8h.