Method for preparing calcium carbonate and co-producing sodium sulfate by using phosphorus gypsum and soda ash

Abstract

The invention discloses a method for preparing calcium carbonate and co-producing sodium sulfate by using phosphorus gypsum and soda ash. The method comprises the following steps of: (1) calculating pure calcium sulfate substance content of a phosphorus gypsum product, feeding the phosphorus gypsum and sodium carbonate solution into a reactor in a mass ratio of pure substances of the calcium sulfate and the sodium carbonate of 1: 0.58-0.78, and performing chemical reaction with slow stirring; (2) filtering a reaction product obtained in the step (1) in a filter to obtain clear sodium sulfate solution and calcium carbonate filter cakes; (3) washing the calcium carbonate filter cakes obtained in the step (2) by using water, centrifuging the solution through a centrifuge, separating solid and liquid, drying the solid through a dryer, and crushing the solid through a first crusher to obtain a calcium carbonate product; and (4) conveying the sodium sulfate solution obtained in the step (2) into a reduced pressure distiller to perform reduced pressure distillation, then cooling a reduced pressure distillation product in a cooler, and crushing the reduced pressure distillation product in a second crusher to obtain a powdery sodium sulfate product.

Description

Technical field

[0001] The present invention relates to the technical field of comprehensive management and utilization of phosphogypsum. Specifically, it relates to a method for preparing calcium carbonate and co-producing sodium sulfate by using phosphogypsum and soda ash. Background technique

[0002] Phosphogypsum is a solid industrial waste discharged during the production of wet phosphoric acid. To produce 1 ton of phosphoric acid (in P 2 O 5 (calculated) can produce 4.5-5 tons of phosphogypsum. With the rapid development of phosphate fertilizer and high-concentration phosphoric acid industry, the discharge of phosphogypsum waste residue is increasing day by day. In 2008, the world's annual emissions of phosphogypsum reached 280 million tons, and my country's annual emissions exceeded 50 million tons, accounting for more than 70% of industrial by-product gypsum. The calcium sulfate content in phosphogypsum exceeds 90% and is an important recycled gypsum resource. Es...

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