Method for extracting silver from silver-containing crude tin alloy

Abstract

The invention provides a method for extracting silver from silver-containing crude tin alloy. The method comprises the following steps of: heating the silver-containing crude tin alloy to reach the temperature of 430 to 500 DEG C for melting; feeding a zinc ingot into the molten silver-containing crude tin alloy, and agitating to dissolve; cooling the dissolved mixture to reach the temperature of 390 to 400 DEG C; and centrifugally separating at a rotating speed of 200-700rpm until the surface of the liquid at the upper layer has no floating slags, so as to obtain the tin liquid at the upper layer and the sliver-zinc slags at the lower layer; naturally cooling and condensing the tin layer to obtain the tin alloy without silver; and distilling the silver-zinc slags under the vacuum to obtain the silver and the crude zinc, wherein the silver in the tin alloy subjected to silver extracting is less than 10g / t. According to the method, the whole process is safe and controllable; the method is convenient to operate, and has no exhaustion of three wastes; and the method has high universality to the raw materials; the tin alloys with different silver contents can be effectively processed; the continuous industrial production can be achieved; and high recovery rate of the tin and the silver can be ensured; the silver in the silver-containing tin alloy can be efficiently extracted; with adoption of the method, the quality of the tin can be improved, and large amounts of silver can be recovered for the enterprises.

Description

technical field [0001] The invention belongs to the technical field of pyrometallurgy of nonferrous metals, and relates to a method for extracting silver from crude tin by high-temperature metallurgy. Background technique [0002] The crude tin produced by reduction smelting of tin ore contains many impurities. Even the tin produced from tin-rich concentrate usually has a purity that cannot meet the requirements of users. Silver is a relatively common associated metal. Usually, the crude tin obtained by reduction smelting contains 40-600g / t silver. Although the presence of silver does not affect the quality of tin, it is important to extract silver from tin and use it. meaning. [0003] Due to the large-scale restrictions on the use of lead-tin solder, a large amount of Sn-Ag-Cu solder is used, which contains about 3% silver, which causes the problem of recycling silver in waste electronic products to become increasingly prominent. [0004] At present, the crude tin refini...

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Problems solved by technology

[0004] At present, the crude tin refining method used to remove silver is mainly electrolysis. Generally, the crude tin with high tin content and low impurity content is refined by fire method. When the crystallizer removes lead and bismuth, silver can be combined with tin and lead. Eutectic is generated, which is an impurity whose temperature is lower than the melting point of tin or close to 183°C. It usually enters the solder, and then the solder is electrolyzed to make the silver enter the anode slime to achieve the purpose of recycling silver; for crude tin with high impurity content, fire method There are many processing procedures, large amount of slag, low direct recovery rate of tin, valuable metals in crude tin are scattered into slag, it is difficult to recover these metals, and the working conditions are not good, and the environmental protection is poor. Electrolytic refining is often used directly. Precious metals gold, silver anode slime

The investment cost of the electrolysis method is large, and there is usually a large amount of metal backlog in the electrolysis process, and because the solder and thick tin usually contain copper, antimony, arsenic, bismuth and other impurities, these impurities have different effects on the electrolysis efficiency, and strict Control its content

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