Polymetallic sulphide

Mukherjee, A. D. Sen, R. Mondal, A. Freibergite from polymetallic sulphide deposits of the Delhi-Aravalli belt Rajasthan. J. Geol. Soc. India 1998, 52, 543-547. 

The polymetallic sulphide deposit at Rudny Altay comprises a number of nearly vertical ore bodies at depths of 450-500 m in a tuff-slate formation. The tuff-slate is covered by dense Mesozoic-Cenozoic clays 40-50 m thick. The lithogeochemical survey does not yield clear anomalies. But the CHIM results for lead delineate satisfactorily the position of the ore bodies and their approximate projection to the surface (Fig. 2-22). 

According to recent epidemiological studies, the majority of cancer cases derive from environmental causes, whose factors are attributed to either the indoor environment or outdoor air pollution and soil contamination (Doll and Peto 1981). In deed, the relative risk of lung cancer mortality increases by some 8—27% in heavily polluted areas (Beeson et al. 1998). Ghazaouet city homes the complex of non-ferrous metals (En-Metanof) which uses the pyrometallurgical process. It uses 100000-115000 t/year of raw material for polymetallic sulphide (El Abed blend), and produces 30000-40000 t/year of Zn, 100-150 t/year of Cd and 50000-80000 t/year of H2SO4. 

By 1990, after a lot of study, it was concluded that a better way of treating the polymetallic sulphides was not in prospect. We were also forced to conclude tliat the gap of lost values was widening and was more likely to get still wider as the mineralogical complexity of the ores processed became worse. Strategically, the industry might be able, for a time, to select, and find, further deposits with easy mineidogy but with the demand for metals increasing this could be no more than a short term palliative. 

The Warner Process sqrplied to polymetallic sulphides would lead to lower cost processing and may in some circumstances be justifiable for that reason alone. Its major cost attraction however is the increased revenue that comes from higher overall recoveries and the increase in unit product prices at the mine. 

For location at or near a mine site, the disposal of sulphur dioxide is rather a different proposition than for smelters located remotely fixrm the mine. Marketing of sulphuric acid is unlikely from most mine sites but safe disposal by reaction of SO2 with calcareous rocks to form insoluble sulfates is an option since often the host rock to polymetallic sulphides is carbonaceous. There is no single answer to this question except that, whatever the location, the sulphur must be safely captured and disposed of and that this does not demand any novel technology but will incur some cost penalty. 

Iron sulphides are a major source of fuel to the process. The oxidation of iron sulphides to form feirosilicate slag does not pose any major technical problem. This process can probably dispose of iron more easily and profitably than can any existing process route. This is a most useful feature because many of the polymetallic sulphides are very pyritic and mineral separation of pyrite from the other sulphides results in losses of values. 

Our studies of the treatment of polymetallic sulphides have now spanned several decades. We cannot see that the future prospects for the production industry can be much better than breaking even over rises and falls in metal prices with the present technology. It is overdue for a fundamental renewal to regain the financial attraction it once had. We believe that the Warner Process is the route for new investment now. 

N.A. Warner, Towards Polymetallic Sulphide Smelting , Complex Sulphides. Processing of Ores. Concentrates and By-products. A.D. Zunkel et al., Eds., TMS-AIME, Warrendale, PA, U.S.A., 1985, 847-865. 

Tailings and slimes dams represent the waste product after crushing, grinding and processing of the ore. Deposition can be in a dry form or hydraulically emplaced in the impoundment. Traditionally these dams are a major source of potential problems from escape of contaminants into the environment. For example a polymetallic sulphide ore can generate elevated anions, cations and metals together with chemical reagents from the process. 

Six sulphide species were observed in the non-ferromagnetic heavy mineral concentrates (NFM-HMCs) of bedrock samples arsenopyrite pyrite > chalcopyrite > bismuthinite = molybdenite = cobaltite. Chalcopyrite, pyrite and bismuthinite do survive in near-surface till but only in minor amounts (<8 grains/sample). Although the Co-rich composition of arsenopyrite is possibly the strongest vector to Au-rich polymetallic mineralization in the study area, sandsized arsenopyrite is absent in C-horizon tills, suggesting that arsenopyrite more readily oxidizes than chalcopyrite and pyrite in till, and therefore is an impractical indicator mineral to detect mineralization using surficial sediments at NICO. 

This type contains a variety of ores, including(a) gold-pyrite ores, (b) gold-copper ores, (c) gold-polymetallic ores and (d) gold oxide ore, usually upper zone of sulphide zones. The pyrite content of the ore varies from 3% to 90%. Other common waste minerals are quartz, aluminosilicates, dolomite etc. 

Sherba, G.N. 1983. Polymetallic massive sulfide deposits of Rudny Altai. In Ivanov, S.N. (ed.). Massive sulphide deposits of the USSR Moscow, Nauka Publishing House, 87-148 (In Russian). 

Lenoble, J.-P., 2004. A comparison of the possible economic returns from mining deep-sea polymetallic nodules, sea floor massive sulphides and cobalt-rich crusts. Proceedings of a workshop held on 26-30 June 2000 in Kingston, Jamaica Volume 1, pp. 424-465 (http// www.isa.org.jp)... 

Such bacteria multiply in very aidic solutions (pH < 4.5). Their greatest amoxmt (on average 10 -10 cell-g" ) are discovered in water of copper sulphide and sulphide-polymetallic ore. The source of energy for them are oxidizing processes of not only protoxide metals in water solutions but also almost all reduced forms of sulphur. Bacteria Leptospira ferrooxidans are also capable of oxidizing protoxide iron with getting energy. These bacteria are close in a number of properties to Thiobacillus ferrooxidans, but as opposed to them do not oxidize sulphur. 

It was concluded that none of the known smelting routes could be adapted to smelt zinc rich sulphide feed with a high slag fall and that, therefore, they would not be suitable for raising the recoveries of value from polymetallic ores. 

R.K. Hanna and N.A.Warner, Process Requirements for the Direct Condensation of Both Zinc and Lead as Metals in Polymetallic Smelting of Zn-Pb-Cu Sulphides , Proc. Non-Ferrous Smelting Symposium 100 Years of Lead Smelting and Refining in Port Pine, The Australasian Institute of Mining and Metallurgy, Melbourne, Australia, 1989, 227-236. 

It is shown that the Velikanov model [6] of polyfunctional conductor (PEC) is a good approximation for the properties of the LVl film. The electrochemistry of PEC had attracted considerable attention in the 1970s with regard to the practical problem of electrochemical processing of chalcogenide (sulphide) compounds, the components of natural polymetallic ores. 

PolyMet Mining Corp. (PolyMet) is advancing the development of the NorthMet Project. The NorthMet deposit is located in northern Minnesota, adjacent to the historic Iron Range. The deposit was discovered in the 1960 s and consists of a large, magmatic, disseminated sulphide, polymetallic deposit with values in Cu, Ni, Co, Zn, Au, Ag and Platinum Group Metals (PGM). The shallow, tabular orebody may be mined by open-pit methods with minimal pre-strip and a low waste ore strip ratio. 

Uranium occurs as concentrations of pitchblende with some coffinite in veinlets along faults, in brecciated zones and in satellite structures associated with the major structure. These minerals may occur also as fine disseminations in selected horizons in the host rocks. Secondary uranium minerals are locally abundant, especially in near-surface portions of deposits. Small amounts of quartz and carbonates are the gangue minerals. Associated minerals vary in type and abundance and determine whether a deposit is classified as monometallic or polymetallic. The latter may contain a wide variety of associated minerals, including sulphides. Hematitization and chloritization are the most common forms of alteration... 

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