Method for removing silver in precious metal concentrate through sulfating roasting

Abstract

The invention discloses a method for removing silver in precious metal concentrate through sulfating roasting. According to the method, the precious metal material and the concentrated sulfuric acid are fully stirred and mixed and then roasted, the selenium content and the arsenic content of the produced roasted product are both smaller than 0.1%, and the removal rate of the selenium and the arsenic is both 99% or above; the method is also characterized in that the roasted product subjected to sulfating roasting is leached for 2 hours by using a weak acid solution containing 50g / L of sulfuric acid at 80 DEG C, leached residues obtained after liquid-solid separation are gold, platinum and palladium concentrates subjected to silver and selenium removal, and silver in the roasted product can be removed by more than 96% on the basis that gold, platinum and palladium do not enter the solution through detection and analysis. The process method is low in investment and simple to operate, and the technical problem of separation of silver and platinum group metals, especially silver and palladium, is well solved.

Description

Technical Field

[0001] The invention relates to an enrichment metallurgical process for a material containing precious metals such as gold, platinum and palladium, and in particular to a method for removing silver from precious metal concentrates by using sulfuric acid roasting. Background Art

[0002] Gold, platinum and palladium precious metal materials / concentrates, especially palladium concentrates, are often accompanied by a large amount of silver. There are many silver-palladium separation technologies, such as reduction smelting, solvent extraction, ion exchange, oxidation-reduction, complexation, and acid-base leaching. Although there are many methods, they all have disadvantages: the biggest disadvantage of the reduction smelting method is the low direct yield, and a small amount of palladium will be volatilized and lost; although the solvent extraction and ion exchange methods can achieve deep separation, they need to be dissolved before separation and enrichment, the process flow is long and there are many restrictions on the impurity components of the raw materials; the complexing agents commonly used in the complexation method include ammonia water, thiourea and oxalic acid, etc., and their direct yield is usually low and the applicability is not wide. At present, most factories at home and abroad use leaching and dissolution and then ion exchange to achieve silver-palladium separation, and finally purify silver-palladium separately. Among them, the leaching and dissolving reagents include hydrochloric acid, nitric acid, aqua regia and hydrogen peroxide. Because the potential of silver and palladium is close, the silver-palladium separation process is long and the difficulty of deep separation is the current technical bottleneck. The method of the present invention adopts a sulfuric acid roasting process, which can achieve short-process and low-cost silver-palladium efficient separation. Summary of the invention

[0003] The purpose of the present invention is to use a sulfuric acid roasting process with low investment, low cost and simple operation to separate silver, selenium, arsenic and gold, platinum and palladium from gold, platinum and palladium precious metal materials. The process can remove more than 96% of silver, more than 99% of selenium and arsenic from the raw materials, and no loss of gold, platinum and palladium.

[0004] The present invention is aimed at nickel-copper-cobalt sulfide materials or oxide materials containing precious metals such as gold, platinum and palladium, and utilizes the fact that precious metals such as gold, platinum and palladium do not react with hot concentrated sulfuric acid, while most base metals including relatively stable silver can react deeply with hot concentrated sulfuric acid. The process method clarifies the amount of concentrated sulfuric acid added, roasting temperature, roasting time and control parameters of roasted sand leaching, and realizes the separation of silver, selenium, arsenic and gold, platinum and palladium.

[0005] The present invention discloses a method for removing silver from precious metal concentrate by using sulfuric acid roasting, comprising the following steps: (a) Mix concentrated sulfuric acid and precious metal materials and stir them thoroughly; the mass ratio of precious metal materials to concentrated sulfuric acid is 1:1-1:2; the typical composition of precious metal materials is: Ni 0-61.41%, Cu 0-30%, Fe 0-10%, S 8-20%, Ag 1-50%, Au 0-20%, Pd 0-20%, Pt 0-20%, Se 0-30%, As 0-5%; (b) Spread the uniformly mixed materials in a muffle furnace, set the roasting temperature to 650-750°C, and the roasting time to 1-2 hours; the thickness of the uniformly mixed materials in the muffle furnace shall not exceed 100 mm; (c) the roasted sand produced after roasting in a muffle furnace is leached with a sulfuric acid solution at 80-90°C for 1-2 hours; the concentration of the sulfuric acid solution is 45-55 g / L; (d) After leaching, the solid and liquid are separated, the filtrate is the silver-containing leaching solution, and the filter residue is the precious metal concentrate after desilvering.

[0006] The characteristic of this method is that it is aimed at the nickel-copper-cobalt based precious metal concentrate, because the base metals silver, nickel, copper and the precious metals gold, platinum and palladium exist in a mutually coated state, which leads to the difficulty in separating the base metals and the precious metals gold, platinum and palladium, and the low alkali metal removal rate affects the enrichment multiples of the precious metals gold, platinum and palladium or the large loss of gold, platinum and palladium.

[0007] The beneficial effects of the present invention are as follows: the present invention fully stirs and mixes the precious metal material with concentrated sulfuric acid and then roasts at 700°C for 2h. Under this process condition, the selenium and arsenic content of the roasted sand produced is less than 0.1%, and the removal rate of selenium and arsenic is more than 99%; the roasted sand after sulfation roasting is leached at 80°C for 2h with a weak acid solution containing 50g / L sulfuric acid, and the leached residue obtained after liquid-solid separation is the gold, platinum and palladium concentrate after silver and selenium removal. According to detection and analysis, more than 96% of the silver in the roasted sand can be removed on the basis that gold, platinum and palladium do not enter the solution. The process method has low investment and simple operation, and well solves the technical problem of separating silver from platinum group metals, especially silver and palladium. DETAILED DESCRIPTION

[0008] The process of the present invention is further described with the following non-limiting examples, which are helpful for understanding the present invention and its advantages, but are not intended to limit the scope of protection of the present invention, which is determined by the claims.

[0009] A process for removing silver from precious metal concentrate by sulfuric acid roasting. The process is applied to the removal of silver from precious metal materials / concentrates or the separation of silver and palladium. The operation is simple, the process flow is short, and the equipment investment is small. More than 96% of the silver in the roasted sand can be removed without gold, platinum, or palladium entering the solution.

[0010] Embodiment 1: The precious metal material and concentrated sulfuric acid were fully stirred and mixed in a mass ratio of 1:1.5, and the uniformly mixed material was spread in a muffle furnace with a layer thickness of 50 mm, and roasted at 700°C for 2 hours to produce roasted sand with a mass 1.2 times that of the raw material. The roasted sand was leached at 80°C for 2 hours with a solution containing 50 g / L sulfuric acid, filtered, dried and weighed. The slag rate was 19%, and the precious metal was enriched by 5.26 times. The components of the liquid and leached slag after desilvering were analyzed. The leaching rates of each element are shown in Tables 2 and 3.

[0011] Embodiment 2: The precious metal material and concentrated sulfuric acid were fully stirred and mixed in a mass ratio of 1:1.5, and the uniformly mixed material was spread in a muffle furnace with a layer thickness of 80 mm. It was roasted at 700°C for 2 hours. The mass of the roasted sand produced was 1.4 times that of the raw material. It was then leached at 80°C for 2 hours with a solution containing 50 g / L sulfuric acid. The desilvered liquid and leached slag were filtered, weighed and analyzed for composition. The leaching rates of each element are shown in Tables 5 and 6.

[0012] Example 3 The precious metal material and concentrated sulfuric acid were fully stirred and mixed in a mass ratio of 1:1.5, and the uniformly mixed material was spread in a muffle furnace with a layer thickness of 60 mm. It was roasted at 700°C for 2 hours. The mass of the roasted sand produced was 1.3 times that of the raw material. It was then leached at 80°C for 2 hours with a solution containing 50 g / L sulfuric acid. The desilvered liquid and leached slag were filtered, weighed and analyzed for composition. The leaching rates of each element are shown in Tables 8 and 9.

Claims

1. A method for removing silver from precious metal concentrate by sulphate roasting, comprising the following steps: (a) Mixing concentrated sulfuric acid and precious metal material and stirring them thoroughly; the mass ratio of the precious metal material to concentrated sulfuric acid is 1:1 to 1:2; Typical composition of precious metal materials: Ni 0~61.41%, Cu 0~30%, Fe0~10%, S 8~20%, Ag 1~50%, Au 0~20%, Pd 0~20%, Pt 0~20%, Se 0~30%, As 0~5%; (b) Spread the mixed materials evenly in a muffle furnace, set the roasting temperature to 650-750°C, and the roasting time to 1-2 hours; (c) the roasted sand produced after roasting in a muffle furnace is leached with a sulfuric acid solution at 80-90°C for 1-2 hours; (d) After leaching, the solid and liquid are separated, the filtrate is the silver-containing leaching solution, and the filter residue is the precious metal concentrate after desilvering.

2. The method for removing silver from precious metal concentrate by sulphate roasting according to claim 1, characterized in that: In step (a), the mass ratio of the precious metal material to the concentrated sulfuric acid is 1:1.

5.

3. The method for removing silver from precious metal concentrate by sulphate roasting according to claim 1, characterized in that: In step (b), the thickness of the material layer of the uniformly mixed materials in the muffle furnace does not exceed 100 mm.

4. The method for removing silver from precious metal concentrate by sulphate roasting according to claim 1, characterized in that: In step (c), the concentration of the sulfuric acid solution is 45-55 g / L.

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