Method for producing fluoride and silicon dioxide

Method for producing fluoride and silicon dioxide

CN
  • CN 1,319,561 A
  • Filed: 04/10/2001
  • Published: 10/31/2001
  • Est. Priority Date: 04/10/2001
  • Status: Abandoned Application
First Claim
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1. The production method of fluorine compound and silicon dioxide mainly comprises the following three steps, wherein in the first step, ammonium fluoride and/or ammonia are/is adopted for absorption according to different existing forms of fluorine in the waste gas containing fluorine in phosphate fertilizer;

  • the second step is to process the absorption liquid;

    the third step is to process the obtained high-concentration ammonium fluoride solution, which is characterized in that ammonium fluoride and/or ammonia are directly introduced into an absorption system, and the temperature of absorption liquid is controlled between 50 ℃ and

    95 ℃

    , so that the finally obtained ammonium fluosilicate solution contains 25-37% of H2SiF6



    3%

    NHF4The absorption can be carried out continuously or in batches, and the solution is cooled, crystallized, separated and dried to obtain the ammonium fluosilicate product;

    ammoniating ammonium fluorosilicate solution with ammonia at 40-80 deg.c, and through batch or continuous two-stage ammoniation with the first stage liquid phase pH being controlled at 7.2-7.5 and the second stage liquid phase pH being controlled over 8, ageing for over 1 hr, filtering, counter current washing and drying to obtain ammonium fluorosilicate solution with specific surface area of 100-180m2Precipitating a silicon dioxide product, and separating silicon dioxide to obtain 30-45% ammonium fluoride mother liquor;

    the fluorine-containing compound is produced from the solution.

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