Method for producing potassium stannate

Abstract

This invention provides a method for producing potassium stannate from tin tetrachloride. The method comprises: (1) reacting tin metal with chlorine to synthesize tin tetrachloride; (2) neutralizing tin tetrachloride with a base, washing the obtained precipitate with water, and separating to obtain metastannic acid; (3) reacting with potassium hydroxide to synthesize potassium stannate, concentrating by evaporation, and drying to obtain potassium stannate final product. The method has such advantages of easy operation, no discharge of toxic waste gases, easy treatment of washing wastewater, few anticorrosive requirements for the equipment, simple process, low cost, and high product purity, whiteness and productivity. The method is suitable for industrial production of high quality potassium stannate.

Description

Technical field [0001] The invention belongs to a production process of inorganic compound potassium stannate, and is a new method for producing potassium stannate by using tin tetrachloride. Background technique [0002] Potassium stannate is an alkaline inorganic compound containing tin. The product is white crystal, easily soluble in water, and the solution is alkaline. Potassium stannate is widely used in electroplating industry, mainly used in electronics industry, automobile manufacturing, canned food boxes, precision instruments and other tin plating; also used in textile printing and dyeing industry, glass, ceramics, coinage and other industries. Potassium stannate is an excellent inorganic tin salt for tin plating. Compared with sodium stannate, it has the advantages of fast electroplating speed and high coating quality; compared with acid tin plating process, it has high plating solution stability and electroplating facilities. Simple and other advantages. [0003] Rega...

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Problems solved by technology

[0004] According to our research on the pilot production of potassium stannate, the above two methods of preparing potassium stannate use concentrated nitric acid as the main raw material, and the reaction will produce a large amount of nitrogen oxides such as nitrogen dioxide gas, which is a very harmful pollution. It needs to be absorbed and treated with lye before it can be discharged

Mix concentrated nitric acid and concentrated hydrochloric acid to react with tin. If the acid is excessive, the reaction will be complete, but the free acid is high, and more alkali is needed for neutralization; if the tin is excessive, the reaction will be incomplete, and there will be a large amount of divalent tin. In addition, electroplating will have a serious impact on the quality of the coating. After the reaction, it is necessary to further oxidize divalent tin with hydrogen peroxide, resulting in a low conversion rate of potassium stannate and increased production costs. Therefore, it is difficult to control the end of the reaction.

The β-stannic acid produced by reacting concentrated nitric acid with tin has poor chemical activity and cannot be dissolved in alkali solution at room temperature. It needs to be eutectic with concentrated alkali at 200°C to 300°C. The synthesis conditions are harsh, the operation is difficult, and energy consumption is increased. Equipment investment and product cost; and the impurities produced by corrosion equipment in the eutectic process are difficult to remove, resulting in low product purity and whiteness. When the product is in use, the solution is turbid or colored after water dissolution, which affects the use effect in applications such as electroplating.

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