Device and process for recycling waste sulfuric acid

Abstract

The invention relates to a method for recycling waste sulfuric acid. The method comprises the following steps: S1, carrying out defluorination pretreatment on waste sulfuric acid; S2, transferring thewaste sulfuric acid into a reaction kettle, and adding magnesium oxide for reaction; S3, carrying out filter pressing on a reaction liquid, transferring waste residues to a waste residue storage tank, and transferring filtrate to activated carbon filtering equipment; and S4, separating a magnesium sulfate mother liquor through a first crystallization kettle, detecting the content of potassium hydrogen sulfate, and determining whether the mother liquor is continuously circulated or recycled after potassium hydrogen sulfate is recycled according to whether the content of potassium hydrogen sulfate in the mother liquor reaches a preset threshold value or not. According to the method and the device, the recovery of potassium hydrogen sulfate in the waste sulfuric acid can be realized; the mother liquor is circularly purified, when the concentration of potassium hydrogen sulfate in the mother liquor does not reach a threshold value, the mother liquor flows back to the reaction kettle to continue to increase the concentration of potassium hydrogen sulfate in the mother liquor, and when the concentration of potassium hydrogen sulfate in the mother liquor reaches the threshold value, themother liquor is transferred to the crystallization kettle, the magnesium oxide is added, potassium magnesium sulfate is generated, separated and discharged, and the low-cost recovery of potassium hydrogen sulfate in the waste sulfuric acid is achieved.

Description

technical field [0001] The invention relates to the technical field of waste acid recovery, in particular to a waste sulfuric acid recovery treatment device and process. Background technique [0002] The annual production of waste sulfuric acid in China exceeds 30 million tons. Most of the waste sulfuric acid contains organic matter and cannot be used directly. The existing technology for treating waste sulfuric acid from organic matter is mainly to crack and regenerate sulfuric acid for reuse. The investment in equipment is huge, and the cost per ton of waste sulfuric acid is extremely high. High production costs and huge losses have brought great pressure on the cost and environment of production enterprises, and are the biggest problems plaguing the production of enterprises. Others include extraction and other treatment processes, which involve the cost of extraction solvent recovery and low sulfuric acid content. Few enterprises apply them. Therefore, seeking economical...

AI Technical Summary

Problems solved by technology

However, due to the different sources of waste acid, the complex composition is different from the production of various sulfates from commercial sulfuric acid

A small amount of organic matter and other components in waste acid have a great impact on the production of sulfate, especially the removal of a small amount of impurities. The existence of a small amount of impurities has a great impact on the salt formation, crystallization, and product quality of sulfuric acid. It is difficult to produce qualified products if the process is improper.

[0008] Due to the different sources of waste sulfuric acid, the composition and ratio of substances in the waste sulfuric acid are different. The waste sulfuric acid encountered by the applicant contains 75-80% sulfuric acid, 5-10% potassium bisulfate, 0.2-0.5% If boron trifluoride and other organic substances are directly recovered from potassium hydrogen sulfate, the crystallization and separation conditions are harsh, the separation is difficult, and the equipment investment is huge, so it is not economically feasible.

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