Process for producing wet method phosphoric acid by medium low grade phosphorus mine

Abstract

A process for preparing phosphoric acid from low-and medium-grade phosphorus ore by wet method includes such steps as countercurrent decomposing of P core by excessive phosphoric acid to generate the solution of calcium dihydrogen phosphate, liquid-solid separation to obtain liquid extract, reacting on sulfuric acid to obtain bihydrated calcium sulfate crystal and phosphoric acid solution, liquid-solid separation to obtain phosphoric acid and phosphogypsum, returning the most of phosphoric acid back to decomposing step, and using the rest as finished product.

Description

technical field [0001] The invention belongs to the field of phosphoric acid production, and relates to a process method for producing wet-process phosphoric acid by using medium and low-grade phosphorous rock. Background technique [0002] Wet-process phosphoric acid is the basic intermediate product of the phosphate compound fertilizer industry and the phosphate industry. It has a very important position and is in great demand. At present, the production of phosphoric acid at home and abroad is to use high-grade phosphate rock (there is no strict standard for the grade of phosphate rock, and the industry is traditionally divided into: high-grade: P 2 o 5 ≥30%, medium grade: 24%≤P 2 o 5 <30%, low grade :P 2 o 5 <24%. Enterprise standards stipulate that phosphate rock used for wet processing should be ≥ 28% P 2 o 5 . ), with the gradual depletion of rich phosphate ore mining, the production cost is gradually increasing, and the utilization of low- and medium-g...

AI Technical Summary

Problems solved by technology

One of the characteristics of low- and medium-grade phosphate rocks is that the content of acid-insoluble impurities (A, I) is particularly high. When phosphoric acid is produced by traditional phosphoric acid production methods, almost all of it enters into phosphogypsum, which greatly reduces the quality of phosphogypsum, resulting in its Comprehensive utilization is difficult

Moreover, due to the high content of impurities in low- and medium-grade phosphate rocks, the decomposition rate of phosphate rocks is often low, and the formation of calcium sulfate wraps to passivate the reaction, and the formation of calcium hydrogen phosphate crystals makes the P 2 o 5 Increased loss, poor crystallization of calcium sulfate and difficulty in separation, poor quality of finished phosphoric acid, etc.

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