Ardealite producing method

Abstract

The invention discloses an ardealite producing method. The method comprises the following steps of (1) mixing concentrated sulfuric acid and process water used in wet phosphoric acid production into a dihydrate crystallization tank to react with phosphate concentrate; (2) feeding reactive slurry into a curing tank for crystallization, then performing separation inside a filtering device A, feeding separated liquid into a diluted acid storage tank, and feeding filtered ardealite into a semihydrate crystallization tank for recrystalization; (3) at the same time when the filtered ardealite is fed into the semihydrate crystallization tank, inletting steam into the semihydrate crystallization tank, meanwhile, adding in concentrated sulfuric acid, and controlling the solid content to be within 20-40% and the temperature to be within 90-110 DEG C; (4) after the slurry completes reaction inside the semihydrate crystallization tank, filtering the reactant inside a filtering device B, performing washing through washing water and then performing drying to obtain semihydrated ardealite. The ardealite producing method is easy to operate and makes full use of washing water used during filtering and washing, thereby having high practical value.

Description

technical field [0001] The invention relates to phosphoric acid, in particular to a method for producing α-type hemihydrate gypsum with dihydrate-semihydrate wet process phosphoric acid. Background technique [0002] Phosphoric acid produced by decomposing phosphate rock with strong inorganic acids (such as sulfuric acid, hydrochloric acid, nitric acid, fluosilicic acid, etc.) can be collectively referred to as wet-process phosphoric acid. In the production of wet-process phosphoric acid, calcium sulfate hydrate exists in three different forms, namely dihydrate, hemihydrate, and anhydrous, depending on the process conditions such as slurry temperature, phosphoric acid concentration, and sulfuric acid dosage in the reaction process. According to the different crystal forms of calcium sulfate produced, the wet-process phosphoric acid production process includes anhydrous process, hemihydrate process, dihydrate process, hemihydrate-dihydrate process and dihydrate-semihydrate p...

AI Technical Summary

Problems solved by technology

With the rapid development of my country's high-concentration phosphorus compound fertilizer and industrial phosphoric acid industry, the amount of by-product phosphogypsum has increased sharply. At present, there is no good way to use phosphogypsum in China. Secondary pollution of water body

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