Method for producing sodium stannate

Abstract

The invention belongs to a technique for producing inorganic compound sodium stannate, and more particularly relates to a method for preparing the sodium stannate by adopting stannic chloride. The technique comprises the steps: (1) neutralizing stannic chloride by alkali, obtaining precipitate and washing by water, solid-liquid separation, and obtaining stannic acid; (2) synthesizing the sodium stannate by using the stannic acid and sodium hydroxide, concentrating, crystallizing, filtering, drying and crushing the sodium stannate, and obtaining the product of sodium stannate. The method has easy operation and complete reaction of all steps, simplifies the process flow, can improve the direct recovery rate of tin, and reduces the production cost, thus being capable of producing the sodium stannate in industrialized scale.

Description

Technical field [0001] The invention belongs to a production process of inorganic compound sodium stannate, in particular to a method for preparing sodium stannate by using tin tetrachloride. Background technique [0002] Sodium stannate is an alkaline inorganic compound containing tin, often with 3 crystal water, the molecular formula is generally written as Na 2 SnO 3 ·3H 2 O, can also be written as Na 2 Sn(OH) 6 . The product is white crystalline powder, tasteless, insoluble in ethanol and acetone, easily soluble in water, and the aqueous solution is alkaline. It loses crystal water when heated to 140°C, and decomposes when exposed to acid. It is easy to absorb moisture and carbon dioxide when placed in the air and become sodium carbonate and tin hydroxide. The most important use of sodium stannate is for electroplating tin and its alloys, such as electroplating tin-zinc, tin-cadmium and tin-copper alloys. The electroplating solution has simple composition, high stability, e...

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Problems solved by technology

Substituting tin ore with a tin grade of 26% for tin concentrate with a tin grade of 46% can also produce qualified sodium stannate, but the tin leaching rate has decreased and the consumption per ton of product has increased

[0006] According to the inventor's research on the pilot production of sodium stannate for many years, the above two methods for preparing sodium stannate all have deficiencies: (1) the indirect method takes expensive refined tin as raw material, and the raw material cost is high

Impurities such as lead and antimony contained in refined tin are higher than the corresponding impurities contained in sodium stannate products produced from these refined tin as raw materials. Therefore, the leaching solution needs to be purified and removed, causing part of the tin to enter the purification slag. It cannot be returned to the process for recycling, which reduces the direct recovery rate of tin

(2) The direct method uses tin concentrate as raw material. Although the price of raw material is low, the impurities such as lead, antimony, arsenic, and iron contained in tin concentrate are higher than the sodium stannate products produced by using these tin concentrate as raw material. The corresponding impurities contained in the slag are much higher. Therefore, the direct method has a heavier burden than the indirect method for purifying and removing impurities (or pre-roasting and removing impurities), and the amount of slag produced is more, the rate of tin slag entering is higher, and the direct recovery rate of tin is higher. low, increased production costs

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