Process for removing F, Cl and As from waste acid by hot air concentration method

Abstract

The invention provides a process for removing F, Cl and As from waste acid by a hot air concentration method. Flue gas generated in the process of smelting non-ferrous metal is subjected to electrical dust precipitation and is used for making acid, and F, Cl and As are contained in dilute acid. The removal process comprises the following steps of: 1) blowing air into a SO3 cooler by using a blower, converting the air into hot air by using a large amount of waste heat released in the process of converting SO2 into SO3, and allowing the hot air to enter the bottom of a concentration tower; 2) pumping the waste acid to the top of the concentration tower by using a waste acid delivery pump, spraying the waste acid from the top of the tower, and allowing the waste acid to fully contact the hot air from bottom to top; 3) making the F and the Cl in the waste acid combined with water vapor and enter a tail gas washing tower 4 in an acid mist form, and pumping alkaline liquor in an alkaline liquor storage tank into the tail gas washing tower by using an alkaline liquor delivery pump, and neutralizing to obtain salt for emission; and 4) cooling concentrated sulfuric acid obtained at the bottom of the concentration tower to remove the As, and performing vulcanization impurity removal to obtain an industrial product such as sulfuric acid. The process has the advantages of small occupied area, short flow, high waste acid treatment capacity and the like.

Description

technical field [0001] The invention relates to a chemical process, in particular to a flue gas acid production process in the field of nonferrous metallurgy, in particular to a process for removing impurities in the acid production process. Background technique [0002] In the non-ferrous smelting industry, wet purification must be carried out before using smelting flue gas to make acid, and the SO 3 Water will generate dilute sulfuric acid, which is mixed with smoke and dust to produce dirty acid containing arsenic, fluorine, chlorine and heavy metals. The dirty acid has no industrial use and must be treated in a harmless manner. At present, the neutralization method of sulfide-removing lime milk is generally used to treat sewage acid. This process method is a countermeasure to make the flue gas dilute acid washing process go smoothly. It is also a relatively mature and common method in the field of sewage acid treatment. process, but this process mainly has the following...

AI Technical Summary

Problems solved by technology

[0003] (1) The system is affected by SO in the flue gas 3 Content restriction, in case of SO 3 As the content increases, the output of dirty acid will increase, but the system cannot increase the processing capacity in time to deal with excessive dirty acid, thus affecting the normal operation of the main system;

[0004] (2) The dilute sulfuric acid in the polluted acid has not been effectively utilized, resulting in waste of sulfur resources;

[0005] (3) A large amount of lime is used in the neutralization of sewage acid, and a large amount of low-quality useless gypsum slag is produced at the same time, which increases the cost of sewage acid treatment;

[0006] (4) Sewage acid treatment process will produce H 2 S, sulfide slag and gypsum slag, the treatment process is long and will cause secondary pollution

Images