Sulfuric acid flow-rate control method for dihydrol wet-method phosphoric acid extraction process

Abstract

The invention discloses a sulfuric acid flow-rate control method for a dihydrol wet-method phosphoric acid extraction process. The method comprises the following steps: detecting CaO mass concentration of ore pulp input to a phosphoric acid extract trough, and converting the CaO mass concentration into the consumption amount of sulfuric acid needed by the CaO; detecting impurity mass concentration of the ore pulp input to the phosphoric acid extract trough, and calculating the consumption amount of sulfuric acid needed by the impurities in a fuzzy reasoning manner; adding up the consumption amounts of the sulfuric acid to obtain the total consumption amount of the sulfuric acid; detecting content of sulfuric acid of the ore pulp output from the phosphoric acid extract trough, calculating a correction coefficient, and correcting the total consumption amount of the sulfuric acid by virtue of the correction coefficient; measuring the flow rate of ore pulp input to the phosphoric acid extract trough, and multiplying the corrected total consumption amount of the sulfuric acid by the flow rate of the ore pulp; and converting the multiplication result to a control current signal so as to control the openness of an electric adjusting valve of the flow rate of the input sulfuric acid. By adopting the sulfuric acid flow-rate control method, the stability of technical indexes can be effectively improved, the quality and economic benefit of a final product can be improved, the consumption of the sulfuric acid is reduced, the environmental pollution is reduced, the automation degree is high, and simplicity in operation is achieved.

Description

technical field [0001] The invention relates to the field of process control of a phosphoric acid production process, in particular to a sulfuric acid flow control method used in a dihydrate wet phosphoric acid extraction process. Background technique [0002] As an important chemical raw material, phosphoric acid plays a pivotal role in my country's chemical industry. Industrial phosphoric acid is usually obtained by extracting phosphate rock with sulfuric acid, and the by-product calcium sulfate (commonly known as phosphogypsum) is generated. Calcium sulfate dihydrate has the advantages of coarse crystal particles and easy filtration and separation, so phosphoric acid manufacturers generally use dihydrate wet phosphoric acid extraction process. [0003] In the dihydrate wet phosphoric acid extraction process, the phosphoric acid extraction tank is a key equipment for sulfuric acid extraction of phosphoric acid. The two main raw materials input into the phosphoric acid ex...

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Problems solved by technology

However, production practice shows that this method has two defects: first, the calculation of the CaO content of the slurry from the liquid-solid ratio is likely to cause a large error, resulting in inaccurate addition of sulfuric acid; second, the impurities of ores from different sources Composition (MgO, Fe 2 o 3 and Al 2 o 3 ) content varies greatly (even if the ore at the same location, the impurity content of different batches of ore is also quite different), resulting in inaccurate addition of sulfuric acid

The inaccuracy of the amount of sulfuric acid added causes the residual sulfuric acid content index of the output pulp to fluctuate in a wide range, thus affecting the crystallization and filtering effect of phosphogypsum, and also affecting the quality of finished phosphoric acid and causing environmental pollution

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