RU2309187C2 - Method of processing auriferous arseno-pyrite ores and concentrates - Google Patents

Abstract

FIELD: metallurgy of noble metals; stripping of gold and extraction of arsenic from auriferous arseno-pyrite ores and concentrates.

SUBSTANCE: proposed method includes roasting of auriferous arseno-pyrite ores in steam atmosphere at temperature in furnace of 973-1023K with the aid of sulfidizing agent in form of off-grade pyrite concentrate at content of sulfur not below 40% in the amount not exceeding 20-30% of mass of ore or concentrate.

EFFECT: removal of arsenic in low-toxic form; increased degree of desulfurizing of raw material; maximum stripping of fine gold.

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Description

The invention relates to the metallurgy of precious metals, in particular to the problem of opening gold and the removal of arsenic from gold-bearing arsenopyrite ores and concentrates.

There is a vacuum-thermal method for processing gold-arsenic sulfide concentrates, which provides a solution to the problem of protecting the environment from pollution by toxic arsenic compounds (Khrapunov V.E., Kenzhaliev B.K., Bolotova L.S., Isakova R.A. Non-ferrous metals. 2001, No. 12, p. 33-35). The main advantage of this technology for preparing arsenic-containing concentrates for further processing is the ability to remove arsenic from the material in one stage with its transfer to low toxic sublimates (arsenic sulfide, metallic arsenic). Sublimates contain 64-99% As and up to 1-35% S, in a neutral environment they are easy to melt and can be poured into compact blocks, convenient for transportation and storage. The cinder contains 0.1-0.3% As. However, subsequent cyanidation provides high gold recovery only from low-iron cinders; high-iron cinders of vacuum thermal firing should be subjected to hydrochloric acid treatment to leach iron and residual arsenic or to carry out oxidative firing. Concentrates containing arsenic in the form of FeAs ₂ , FeAs can be purified from arsenic by a vacuum thermal method only with the introduction of the required calculated amount of sulfur (in the form of pyrite, elemental sulfur). Technology requires sophisticated vacuum furnaces and equipment.

There is also a method for processing arsenic-containing raw materials (Isabaev S.M., Pashinkin A.S., Milke E.G., Zhambekov M.I. Physicochemical principles of sulfidation of arsenic-containing compounds. Alma-Ata: Nauka, 1986), which provides for oxidatively - sulfidizing roasting of arsenic-containing materials in the presence of pyrite, sulfur, sulfur dioxide and chalcopyrite with the extraction of arsenic in the form of sulfides. The process is carried out in a shaft-type furnace. The advantage of the process is the possibility of a fairly complete removal of arsenic from the material and its translation into a compact non-toxic form, convenient for storage, transportation as raw materials for commercial products.

The closest analogue to the combination of essential features and purpose is the patent EP 0508542 A2 IPC С22В 1/02, publ. 10/14/1992, in which a method for processing gold-containing arsenopyrite ores and concentrates is disclosed, including calcining them with various additives, including pyrite at a temperature of 475-900 ° C in an atmosphere of superheated steam with the removal of arsenic compounds and the extraction of gold from the resulting cinder.

The disadvantages of the method include: the use of pure pyrite as a sulfidizing agent, expensive elemental sulfur and the need for an additional process of additional oxidation of residual sulfur at the outlet of the cinder from the shaft furnace with an increase in air supply in the countercurrent circuit, mechanical activation or autoclave processing of the cinder to extract gold and silver according to the traditional hydrometallurgical scheme processing.

The technical result of the invention is the removal of arsenic in low toxic form and an increase in the degree of dearsenization and desulfidization of raw materials, the opening of fine and fine gold from gold-bearing ores and concentrates.

The technical result is achieved by the fact that gold-containing arsenopyrite ores and concentrates are calcined in an atmosphere of superheated water vapor with a sulfidizer at a temperature of 973-1023 K. Substandard pyrite concentrate with a sulfur content of at least 40% is used as a sulfidizer. The amount of pyrite concentrate is not more than 20-30% by weight of gold-bearing arsenopyrite ore or concentrate. When a mixture is fired in an atmosphere of superheated water vapor, thermal dissociation of arsenopyrite with the release of elemental arsenic occurs, while thermal dissociation of pyrite to pyrrhotite and elemental sulfur occurs. Pyrrhotite in the atmosphere of water vapor is oxidized to magnetite with the release of hydrogen sulfide and hydrogen. At a given temperature, vapors of elemental arsenic in the atmosphere of superheated water vapor and hydrogen interact with vapors of elemental sulfur and hydrogen sulfide to form arsenic sulfides. During the thermal dissociation of arsenopyrite, it decrypts both fine and fine gold and is opened from arsenopyrite grains. Arsenic sulfides are removed from the reaction zone separately from the cinder containing gold, which is sent for further processing by traditional methods of gold recovery.

Example 1. The firing temperature of 873 K.

Table 1 Product Exit Content% Distribution% g % As S As S Charge 50.00 100.00 7.20 18.24 100.00 100.00 Cinder 40.22 80,44 1.95 7.79 21.78 34.35 Dust 0.38 0.76 1.80 50,44 0.19 2.10 Condensate 8.12 16.24 34.23 62.59 77.21 55.73 Discrepancy 1.28 3.56

Example 2. Firing temperature 973 K

table 2 Product Exit Content% Distribution% g % As S As S Charge 50.00 100.00 7.20 18.24 100.00 100.00 Cinder 36.62 73.24 0.21 3.74 2.14 19.03 Dust 0.30 0.60 0.17 53.33 0.02 1.75 Condensate 11.21 22.42 31.40 59.31 97.78 72.90 Discrepancy 1.87 3.74

Example 3. The firing temperature of 1023 K.

Table 3 Product Exit Content% Distribution% g % As S As S Charge 50.00 100.00 7.20 18.24 100.00 100.00 Cinder 33.88 67.76 0.01 1,62 0.01 6.02 Dust 0.50 1.00 0.16 56.00 0.02 3.07 Condensate 13.68 27.36 26.24 55.84 99.71 83.76 Discrepancy 1.94 3.88

Sulfidizing roasting of gold-bearing arsenopyrite ores and concentrates in an atmosphere of water vapor allows to obtain an oxidized cinder and to drive off arsenic as a low-toxic product - sulfide. The degree of dearsenization is 99.5-99.7%, the degree of desulfidization is 94-95%. A high degree of desulfidization of the feedstock eliminates the need for additional oxidation of residual sulfur. This method allows to increase the degree of gold recovery by about 40%.

Claims (1)

A method of processing gold-containing arsenopyrite ores and concentrates, including firing them with a sulfidizer at a temperature of 973-1023 K in an atmosphere of superheated water vapor with the removal of arsenic compounds and extracting gold from the cinder, characterized in that the firing is carried out using substandard pyrite concentrate with sulfur content of not less than 40% in an amount of not more than 20-30% by weight of ore or concentrate with the formation and removal of arsenic compounds in the form of arsenic sulfide.