Method for joint production of ammonium sulphate and calcium carbonate with phosphogypsum

Abstract

The invention discloses a method for co-producing ammonia sulfate and calcium carbonate by ardealite. The method comprises that: the ardealite serous liquid is taken and added into a reaction kettle; a stirrer is started, and the reaction kettle is heated up to the temperature of between 30 and 60 DEG C; an additive and (NH4)2CO3 are added into the reaction kettle, the reaction temperature is controlled to be between 30 and 60 DEG C, and the reaction time is between 0.5 and 2 hours; after the reaction, the heating device and the stirrer are closed, the mixture in the reaction kettle is cooled down to the normal temperature and filtered, the pH value of the filtrate is adjusted to be between 5.5 and 6.0, and the filtrate is condensed, crystallized and dried to obtain the ammonia sulfate product; the filter residue is added with water to obtain solid pulp of which the content of CaCO3 is between 30 and 60 percent, and the solid pulp is placed into a reactor; and the stirrer is started, and solid pulp is heated up to the temperature of between 70 and 90 DEG C and mixed with a surface modifier, the reaction temperature is maintained for 0.5 to 1 hour, the heating device is closed, the mixture is continuously stirred, cooled down to the temperature of between 30 and 50 DEG C and filtered, and the filter residue is dried to obtain the modified CaCO3. The method has the advantages of preparing the ammonia sulfate and the calcium carbonate at the same time and improving the utility value of the calcium carbonate, along with simple process, high recovery rate and low production cost.

Description

technical field [0001] The invention relates to the field of chemical industry, in particular to a method for co-producing ammonium sulfate and calcium carbonate by using phosphogypsum. Background technique [0002] Phosphogypsum is an industrial waste discharged from the production process of wet-process phosphoric acid. Due to different production processes, it will contain dihydrate gypsum and hemihydrate gypsum, with dihydrate gypsum as the main component. In addition, it also contains a small amount of undecomposed phosphate rock powder, free phosphoric acid, iron phosphate, aluminum phosphate and fluorosilicate and other impurities. The annual discharge of phosphogypsum in my country has exceeded 50 million tons, which not only occupies a large amount of land, but also seriously pollutes the environment. [0003] At present, ammonium sulfate is mostly produced by neutralizing synthetic ammonia and sulfuric acid to obtain ammonium sulfate, but the synthetic ammonia pr...

AI Technical Summary

Problems solved by technology

The annual discharge of phosphogypsum in my country has exceeded 50 million tons, which not only occupies a large amount of land, but also seriously pollutes the environment

[0003] At present, ammonium sulfate is mostly produced by neutralizing synthetic ammonia and sulfuric acid to produce ammonium sulfate, but the synthetic ammonia process is complicated, so the production cost is high and cannot meet the needs of the market

The type and content of impurities in the industrial waste phosphogypsum of wet-process phosphoric acid are relatively high, which affects the conversion rate of ammonium sulfate from phosphogypsum. However, the content of calcium carbonate in the product is low and the particle size is large, which cannot reach the level of rubber, paint, PVC and Plastic Filler Requirements

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