Method for preparing magnesium sulfate from anthraquinone waste acid

Abstract

The invention discloses a method for preparing magnesium sulfate from anthraquinone waste acid, which comprises the following steps of: standing and separating the anthraquinone waste acid to obtain a dilute sulphuric acid solution and sediment; mixing and reacting the dilute sulfuric acid solution, magnesium oxide and 98wt% concentrated sulfuric acid to obtain a solid-liquid mixture; performing solid-liquid separation on the solid-liquid mixture to obtain magnesium sulfate mother liquor and a filter cake; sequentially carrying out heating concentration, cooling crystallization and centrifugal separation on the magnesium sulfate mother liquor to obtain mother liquor to be purified and magnesium sulfate crystals; adding an organic extraction agent into the mother liquor to be purified to adsorb impurities, and separating to obtain sludge sediment and purified mother liquor; returning the purified mother liquor to the concentration stage; the method is simple and easy to implement, impurity sedimentation can be achieved only by adding the organic extraction agent, recycling of mother liquor is achieved, the utilization rate of waste acid is increased, and economic maximization is achieved.

Description

technical field [0001] The invention relates to the technical field of waste acid reuse, in particular to a method for preparing magnesium sulfate by using anthraquinone waste acid. Background technique [0002] At present, a large amount of waste sulfuric acid is produced in the production process of 2-ethylanthraquinone. The waste sulfuric acid contains sludge and sediment, which cannot be reused. The direct discharge needs to be treated, the energy consumption is too large, and it will also cause dilute sulfuric acid in the waste acid. portion wasted. [0003] The traditional treatment method is to use waste acid to prepare magnesium sulfate. The magnesium sulfate mother liquor after crystallization in the preparation of magnesium sulfate process is generally used as a circulating fluid to return to the front-end process for production. The sludge in the magnesium sulfate mother liquor (for granular) It will continue to accumulate during the production process, which wil...

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Problems solved by technology

[0002] At present, a large amount of waste sulfuric acid is produced in the production process of 2-ethylanthraquinone. The waste sulfuric acid contains sludge and sediment, which cannot be reused. The direct discharge needs to be treated, the energy consumption is too large, and it will also cause dilute sulfuric acid in the waste acid. waste of portion

[0003] The traditional treatment method is to use waste acid to prepare magnesium sulfate. The magnesium sulfate mother liquor after crystallization in the preparation of magnesium sulfate process is generally used as a circulating fluid to return to the front-end process for production. The sludge in the magnesium sulfate mother liquor (for granular) It will continue to accumulate during the production process, which will eventually affect the concentration and crystallization effect, resulting in a decrease in yield. After the impurities accumulate to a certain extent, the magnesium sulfate mother liquor must be discharged or replaced; due to the continuous accumulation of impurities, a large number of bubbles will be generated during the concentration process. Small black particles, the traditional treatment method is achieved through secondary crystallization, but due to the excessive content of impurities in the magnesium sulfate mother liquor during the secondary crystallization, the size of the magnesium sulfate crystal particles is uneven, and there are also black particles, and the separation needs to be separated by a scraper centrifuge The realization of separation makes the whole process longer, and the magnesium sulfate mother liquor obtained by secondary crystallization cannot be circulated indefinitely, and needs to be discharged regularly

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