Method for preparing ultra-fine calcium sulfate crystal whisker by using phosphogypsum

Abstract

The invention discloses a method for preparing ultra-fine calcium sulfate crystal whiskers by using phosphogypsum. The method comprises that the phosphogypsum is ultra-fine treated to powder with grain size of 0.1-100 mum, water is added into the powder to prepare slurry with weight percent of 5-15 percent, pH value is regulated to be 3-5, reaction is kept for 3-5h at 125-145 DEG C and under 2-3MPa, pumping filtration is conducted when the obtained product is hot, and the filtered product is dried at 120-250 DEG C to obtain the calcium sulfate crystal whiskers. Moreover, crystal promoter with weight 0.10-0.20 time of the weight of the phosphogypsum and seed crystal with weight 0.1-0.2 time of the weight of the phosphogypsum can be added. The invention has the advantages of low production cost, simple production method and good comprehensive performance.

Description

technical field

[0001] The invention relates to the field of chemical engineering, in particular to a method for preparing calcium sulfate whiskers. Background technique

[0002] Phosphogypsum is an industrial waste produced during the production of wet-process phosphoric acid. In the traditional wet-process phosphoric acid manufacturing process, every 1t of wet-process phosphoric acid produced (in P 2 o 5 Total) by-product phosphogypsum is about 4-5 tons, and the annual discharge of phosphogypsum in the world is close to 200 million tons. But the actual utilization rate is less than 1 / 10 of the total. A large amount of phosphogypsum is stacked in the open air, occupying land and seriously polluting the environment, which has become a worldwide problem. The main component of phosphogypsum is calcium sulfate (dihydrate gypsum content is about 85%), and the impurity content varies with raw materials, process routes, and operating conditions. Among the impurities, soluble ...