Method for extracting aluminum salt and recycling waste acid from acid solution containing aluminum salt

Abstract

The invention discloses a method for extracting aluminum salt and recycling waste acid from an acid solution containing aluminum salt. The method has the following overall steps: carrying out evaporative concentration on the acid solution containing aluminum salt, so as to control the acid concentration to 35%-70%; pumping the concentrated acid solution into a crystallizing pond, and separating aluminum salt crystals from the acid solution; carrying out filter pressing on separated aluminum salt, so as to obtain an aluminum salt filter cake relatively low water content and acid content; crushing the filter cake; carrying out three-grade countercurrent cleaning on the crushed filter cake; and drying the cleaned filter cake. By virtue of the method, the problems that the acid content and water content of aluminum salt are extremely high after the acid solution containing aluminum salt is subjected to centrifugal concentration, and a product is relatively poor in quality and low in use value in the prior art are solved. The evaporative concentration is carried out in a multiple-effect evaporation manner or a mechanical compression and evaporation manner in the process, so that the energy consumption is very low; aluminum salt and acid are recycled for use; the purity of aluminum salt in a final product is very high.

Description

technical field [0001] The invention relates to an extraction and recovery method, in particular to a method for extracting aluminum salt from an acid solution containing aluminum salt and recovering waste acid. Background technique [0002] At present, a large amount of acid solutions containing aluminum salts are produced in production activities in the fields of petroleum, chemical industry, and medicine. People usually use the methods of adding resin adsorption-backwashing and lime precipitation to recover the waste acid in the acid solution, but the former has the possibility of recycling The defects of low acid concentration and low production efficiency, and the latter is very easy to produce gypsum slag in the recovered acid solution, thereby affecting the quality of the recovered acid solution. In addition, neither of these two methods can completely solve the problem of the emission of incompletely treated aluminum ions into the environment, and aluminum ions have ...

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Problems solved by technology

However, because the crystallization properties of aluminum salts are similar to colloids, the obtained crystals contain acid and extremely high water content, which makes the quality of the obtained products worse and the use value is low, thus restricting the wide application of aluminum salt crystals in many fields

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