An alkaline refining example

In order to prevent bismuth and tin from being simultaneously slag in alkaline refining, a process of removing bismuth and then removing tin is adopted to facilitate the separate recovery of bismuth and tin.

The addition of bismuth solution after oxidation refining arsenic, antimony, down to 500 ~ 520 ℃, feed was added 1.5% to 2% by weight of the solid base, after melting, bubbling air in addition to tellurium, solid base was added several times, in addition to tellurium The refining time is generally controlled at 6 to 10 hours, and the added solid base does not dry out under the agitation of compressed air, which is the end point of the deodorization. In addition to the sputum after sputum, the cerium content is reduced to less than 0.05%, and in the subsequent refining process, the mites can be further effectively removed, so that it is not necessary to excessively extend the mites operation time, so as to avoid a large amount of lean slag and reduce The direct yield of hydrazine. The slag is light yellow and weighs about 3% to 5% by weight.

After removing the slag, cool down to 400-450 ° C, add NaOH and NaCl, melt and cover the surface of the mash, stir with the compressed air for 15-20 minutes, add NaNO ₃ , stir for 30 minutes, then remove the dry Slag. The amount of the base added was Sn:NaOH:NaCl:NaNO3 = 1: ₂ :0.6:0.5. The operation was repeated three times, the first addition amounted to 3∕5 of the total addition amount, the second time was 1/5, and the third time was 1/5. The amount of tin slag is about 1% to 3% of the weight of the material.

The alkaline slag components produced by alkaline refining in a plant are shown in the following table, from which strontium and sodium stannate are separately recovered.

Table Basic refining slag composition (%)

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