RU2337162C1 - Method of processing of sulphide concentrates - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: method includes mixing of source concentrate with calcium oxide CaO and calcium peroxide CaO₂ and burning in two stages. At the first stage burning is carried out at temperature of 350-500°C within 30-40 minutes, at the second stage - at temperature of 500-800°C during 30-60 minutes. After burning there is performed leaching of non-ferrous metals out of cinder. Consumption of calcium oxide CaO is 50-100% from stoichometric required for binding sulphur into gypsum while consumption of calcium peroxide CaO₂ is 1-10% from concentrate weight.

EFFECT: increased extraction of non-ferrous metals and reduced duration of cinder leaching.

2 cl, 2 tbl, 2 ex

Description

The invention relates to the metallurgy of non-ferrous metals, in particular to methods for thermohydrometallurgical complex processing of concentrates and sulfide intermediate products, and can be used to extract non-ferrous and noble metals.

The traditional processing of sulfide ores and concentrates, such as copper, is reduced to smelting to obtain iron-containing slag and matte, which is then converted, and blister copper is refined by electrolysis. To partially remove sulfur, the concentrates are oxidatively fired to form sulfur dioxide before melting.

Firing of zinc concentrates is carried out with complete sulfur oxidation. The cinders are leached in circulating solutions of sulfuric acid, zinc is extracted from the resulting solutions by electroextraction / (1) Processes and apparatuses of non-ferrous metallurgy. Naboychenko S.S. et al. - Yekaterinburg: GOU VPO USTU-UPI, 2005 /.

For hydrometallurgical processing of cinder, firing is sought to be carried out in modes that ensure the conversion of recoverable metals to soluble sulfate, and iron to a stable oxide form. Sulfatizing firing is based on moderate temperatures (600-700 ° C) and a limited excess of air. The process speed under such conditions drops sharply, and the duration, accordingly, increases.

The closest in technical essence is a method of processing sulfide copper concentrates, including sulfatizing roasting of the initial concentrate at a temperature of 500-600 ° C for 90-180 minutes, the cinder is leached with a solution of sulfuric acid or water with separation of cake and filtrate. Copper from the filtrate is isolated by electrolysis, and cake is processed to extract precious metals / (2) Patent Ru No. 2255126 from 2005.06.27. Thermohydrometallurgical method of complex processing of copper concentrate of pyrite ores with extraction of non-ferrous and precious metals.

The main goal of sulfatizing firing is to obtain readily soluble non-ferrous metal compounds in a cinder. The firing conditions for the prototype method do not allow to achieve this goal in full. The research results and the practice of using sulfatizing firing and copper and zinc concentrates show that hardly soluble non-ferrous metal ferrites are inevitably present in the cinder. Even under severe conditions of cinder leaching - a temperature of 90 ° C and a sulfuric acid concentration of 100-150 g / dm ³ - zinc extraction into the solution does not exceed 80%. The leaching duration is at least 4-5 hours.

The present invention is aimed at eliminating this drawback and has the objective of increasing the speed and degree of extraction of non-ferrous metals into the solution after sulfatization firing.

The specified technical result is achieved by the fact that the initial concentrate is mixed with calcium oxide CaO and calcium peroxide CaO ₂ and firing is carried out in two stages: the first at a temperature of 350-500 ° C for 30-40 minutes, the second at a temperature of 500-800 ° C for 30-60 minutes. The consumption of calcium oxide CaO is 50-100% of the stoichiometrically necessary for the binding of sulfur to gypsum, and the consumption of calcium peroxide CaO ₂ is 1-10% by weight of the concentrate.

The essence of the alleged invention lies in the fact that in the presence of calcium-containing additives, in particular CaO, the mechanism of the firing process changes. Sulfate sulfur, formed under the conditions of sulfatizing firing, in the presence of calcium-containing additives is associated primarily with calcium. The thermodynamic features of this process lead to lower temperatures of the onset of sulfur oxidation with the transition to autocatalytic mode even at temperatures of 450-500 ° С. At such low temperatures, the formation of ferrites does not occur and the subsequent leaching of the cinders proceeds more fully and at a faster rate. To accelerate firing at low temperatures, calcium peroxide is introduced into the mixture before firing. Active atomic oxygen released during the thermal decomposition of peroxide oxidizes sulfide sulfur even under such conditions. For a more efficient use of calcium peroxide in the first stage, the temperature should not exceed 500 ° C, at higher temperatures it decomposes. The required firing duration in the first and second stages depends on the properties of the initial concentrates (particle size, sulfur content), the design of the firing apparatus and, according to research data, should be 30-40 minutes and 30-60 minutes, respectively.

A cinder containing oxides and, to a lesser extent, sulfates of non-ferrous metals, is leached in acid solutions. Since the ferrite content in this material is minimal, the extraction of non-ferrous metals in the solution is higher than in known methods, in particular when using the prototype method. From the resulting solutions, non-ferrous metals are recovered by known methods, for example by electrolysis.

To solve the main task of this invention is to increase the speed and degree of extraction of non-ferrous metals into the solution, after firing, it is necessary to prevent the formation of ferrites to the maximum extent. The consumption of calcium oxide CaO should be 50-100% of the stoichiometrically necessary for the binding of sulfur to gypsum, and the consumption of calcium peroxide CaO ₂ - 1-10% by weight of the concentrate.

The implementation of the proposed method is discussed in the following examples.

Example 1. Samples of 100 g of copper (21% Cu, 27% Fe, 38% S) and zinc (42% Zn, 6% Fe, 39% S) concentrates were fired according to the method of the prototype (at a temperature of 600 ° C for 120 minutes) and according to the proposed method with trimming CaO and CaO ₂ to concentrates at a temperature of also 600 ° C. The resulting cinder was leached with a solution of sulfuric acid of 100 g / l at a temperature of 90 ° C. The resulting solutions were filtered from the undissolved residue, analyzed for copper and zinc, and the extraction of these metals into the solution was calculated. The results are shown in table 1.

Table 1
The results of firing and leaching experiments Firing conditions Duration of cinder leaching, h The degree of leaching,% CaO additive,% Additive CaO ₂ ,% copper from copper zinc from zinc. to Prototype (no additives) 3 68 57 The proposed method thirty 0 one 28 19 2 41 37 3 70 44 fifty one one 48 35 2 79 62 3 83 74 75 5 one 69 54 2 81 77 3 92 84 one hundred 10 one 72 57 2 85 79 3 94 88 110 12 one 73 57 2 84 80 3 93 87

The dosage of CaO is given in% of the stoichiometrically necessary amount for binding sulfur to gypsum; dosage of CaO ₂ - in% by weight of the concentrate.

Example 2. These concentrates were mixed with CaO (75%) and CaO (5%), calcined in two stages. First, at a temperature of 350-500 ° C, then at a temperature of 500-800 ° C. The cinders were leached for 2 hours, the solutions were analyzed and the extraction was calculated analogously to example 1. The results are shown in table 2.

A comparative analysis of known technical solutions, including the method selected as a prototype, and the present invention allows us to conclude that it is the totality of the claimed features that ensures the achievement of the perceived technical result. The implementation of the proposed technical solution makes it possible to increase the extraction of copper from sulfide concentrates in comparison with the prototype by 25-30%, and zinc by 30-35%. The duration of leaching of non-ferrous metals from the cinder is reduced by 1.5-2 times.

table 2
The results of the firing during stage firing. Firing conditions The degree of leaching,% No. op. Stage 1 2 stage Temperature ° C Duration min Temperature ° C Prolosity, min copper from copper zinc from zinc. to one 300 twenty 450 25 49 36 2 350 thirty 500 thirty 83 74 3 400 35 700 45 92 89 four 500 40 800 60 96 92 5 500 60 900 90 96 91

Claims (2)

1. A method of processing sulfide concentrates, including sulfatizing roasting of the concentrate and leaching of the cinder with the release of metals, characterized in that the initial concentrate is mixed with calcium oxide CaO and calcium peroxide CaO ₂ , firing is carried out in two stages, at the first at a temperature of 350-500 ° C for 30-40 minutes, in the second - at a temperature of 500-800 ° C for 30-60 minutes. 2. The method according to claim 1, characterized in that the consumption of calcium oxide CaO is 50-100% of the stoichiometrically necessary for the binding of sulfur to gypsum, and the consumption of calcium peroxide CaO ₂ is 1-10% by weight of the concentrate.