Method for preparing calcium sulfate hemihydrate whiskers by taking ardealite as main raw material

Abstract

The invention relates to a method for preparing calcium sulfate hemihydrate whiskers by taking ardealite as a main raw material. The technical scheme of the invention is as follows: firstly, mixing 40-50wt% of ardealite with 3-5wt% of hydrochloric acid, 1-3wt% of sulfuric acid and the balance of water as accessory materials, stirring the obtained mixture for 1-2 h at normal pressure and at a temperature of 80-110 DEG C, and filtering the obtained product so as to obtain a primary filter cake, and washing the primary filter cake; preparing 6-12wt% of habit modifier, 1-5wt% of sulfuric acid, 1-10wt% of primary filter cake subjected to washing and the balance of water into turbid suspension liquid; then, under the condition of normal pressure and 100-120 DEG C, stirring the turbid suspension liquid for 0.5-1 h, adding calcium sulfate whiskers accounting for 0.5-1wt% of ardealite and a whisker modifier accounting for 0.5-1wt% of ardealite while stirring, and then stirring for 4-8 h; carrying out filtering on the obtained product so as to obtain a finished filter cake product, and washing the finished filter cake product; and finally, drying the finished filter cake product for 2-4 hours so as to obtain the calcium sulfate hemihydrate whiskers. The method disclosed by the invention has the characteristics of mild operating condition, low production cost, green and environmental protection, and high product quality.

Description

technical field [0001] The invention belongs to the technical field of calcium sulfate hemihydrate whisker preparation. In particular, it relates to a method for preparing calcium sulfate hemihydrate whiskers by using phosphogypsum as the main raw material. Background technique [0002] Phosphogypsum is a kind of industrial waste discharged during the production process of wet-process phosphoric acid. About 5t of phosphogypsum is discharged for every 1t of phosphoric acid produced. At present, the domestic discharge of phosphogypsum is about 50 million t / a, accounting for more than 70% of the industrial by-product gypsum, and it is still growing at a rate of 15% per year, but its effective utilization rate is less than 10%. The storage of phosphogypsum waste slag not only costs a lot of money and occupies a lot of fertile land, but also easily pollutes the atmosphere, water system and soil due to wind erosion and rain erosion. At the same time, phosphogypsum is also an im...

AI Technical Summary

Problems solved by technology

At present, the domestic discharge of phosphogypsum is about 50 million t / a, accounting for more than 70% of the industrial by-product gypsum, and it is still growing at a rate of 15% per year, but its effective utilization rate is less than 10%.

Because the dissolubility of calcium sulfate is relatively small, the calcium sulfate whisker product quality that the first kind of preparation technology obtains is high, but needs to consume a large amount of acid, and output is less; And second kind of preparation technology not only needs to adopt high-pressure hydrothermal reaction, and Impurities such as phosphorus, fluorine, and metal ions in phosphogypsum have not been removed in advance, resulting in high impurity content in the product and poor color of the product