Method for preparing sodium stannate from stannic oxide and sodium salt in reduction roasting manner

Abstract

The invention discloses a method for preparing sodium stannate from stannic oxide and sodium salt in a reduction roasting manner. The method comprises the following steps of firstly and respectively grinding stannic oxide and sodium salt additive to meet the following requirement that the mass percent of grinded stannic oxide and sodium salt additive with particle grade of -0.1mm is not less than 90%, and uniformly mixing grinded stannic oxide and sodium salt additive according to a mass ratio of 1:(0.8-1.6); blocking the mixture, drying and placing the mixture under reduction atmosphere to heat and roast, wherein coke powder or anthracite is served as a reduction agent, the roasting temperature is 800-950 DEG C, and the roasting time is 30-90min; and after cooling down the roasted blocks, sequentially carrying out treatments of grinding and soaking, filtering, purifying and impurity removing, and concentrating and crystallizing to obtain products of sodium stannate. Compared with the traditional sodium stannate preparation process, the method for preparing sodium stannate from stannic oxide and sodium salt in the reduction roasting manner, disclosed by the invention, has the characteristics of strong raw material suitability, high tin conversion rate, low cost, small investment, simple operation, environmental friendliness and the like; the whole reduction roasting process is carried out under a solid condition without special requirements in a roasting device; and the industrial production is easy to be realized.

Description

technical field [0001] The invention relates to a preparation method of sodium stannate, in particular to a method for preparing sodium stannate by reduction roasting of tin dioxide sodium salt. Background technique [0002] The chemical formula of sodium stannate is Na 2 SnO 3 ,White powder. Sodium stannate is an earlier tin chemical product, and its most important use is for alkaline tin plating and its alloys in the electroplating industry (such as tin-zinc, tin-cadmium, tin-copper, tin-aluminum alloy, etc.). In addition, the textile industry is also used as fire retardant, weighting agent; the dye industry is used as a mordant; it is also used in glass, ceramics and other industries. The reported preparation method of sodium stannate mainly contains three kinds: [0003] 1) Alkali analysis method. First, fine tin is made into shaving tin, and then sodium stannate paste is synthesized in a thermal synthesis pot with sodium hydroxide, sodium nitrate and water, and the...

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Problems solved by technology

Due to the existence of reverse processing in this production process, energy and materials are wasted. At the same time, due to the low melting point of metallic tin, the specific gravity is larger than that of molten alkali. As soon as the reaction starts, the tin melts and sinks to the bottom of the pot, which is not conducive to the progress of the reaction and leads to the transformation of tin. Low rate, generally only 40%~70%

In the patent "Production Method of Directly Preparing Sodium Stannate from Tin Concentrate" (Application No.: 85104036), its main process and principle are similar to the above-mentioned alkali fusion method, using cassiterite concentrate as raw material to directly prepare sodium stannate , but this type of method still uses sodium hydroxide as the reactant, the whole reaction is completed in the molten state, the reaction time is long, and the corrosiveness of sodium hydroxide puts forward strict requirements on the equipment

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