Method for producing manganese sulfate by recycling low-concentration sulfur dioxide flue gas from aluminum electrolytic cells

Abstract

The invention provides a method for producing manganese sulfate by cyclically utilizing low-concentration sulfur dioxide smoke in an aluminum electrolysis cell. The invention relates to low-energy-consumption resource utilization for low-concentration SO2 smoke treatment and waste treatment in the aluminum electrolysis industry, belonging to the fields of energy saving, emission reduction and environmental protection. The method provided by the invention comprises the steps as follows: a chimney subjected to anti-corrosion treatment for exhausting aluminum electrolysis cell smoke is used as atwo-stage absorption tower; an aqueous solution containing MnO is used as an absorption solution; the exhausted SO2 smoke is directly absorbed by adopting an atomization spray and cyclic absorption mode; the nearly saturated solution containing 10-50wt% of manganese sulfate, generated in the reaction, is prepared into a manganese sulfate product through filtration, multiple-effect evaporation andflash vaporization crystallization; and after the residual sulfuric acid mist in the smoke is subjected to demisting treatment, the smoke is exhausted in accordance with the standards. The method provided by the invention can provide technical support for solving the high-standard exhaust problem of the low-concentration SO2 smoke in the aluminum electrolysis cell, enables harmful constituents inindustrial waste gas to be effectively utilized, realizes the sustainable development of resources and environments, has the advantages of low engineering investment, high SO2 absorption efficiency and low operation energy consumption, and can meet higher requirements for environmental protection and exhaust in accordance with the standards.

Description

technical field [0001] The invention relates to low-concentration SO in the aluminum electrolysis industry 2 The low-energy resource utilization of flue gas treatment and treatment waste belongs to the field of energy conservation, emission reduction and environmental protection. Background technique [0002] In the process of aluminum electrolysis, due to the electrochemical reaction between carbon anode and alumina in the cryolite melt, a certain amount of SO will be produced. 2 , CO 2 And fluorine-containing fumes, these harmful fumes will cause harm to human health and pollute the environment. For this reason, many aluminum electrolysis enterprises have carried out the alumina adsorption treatment of fluorine-containing flue gas, so that the exhausted flue gas contains fluorine and SO 2 The amount reaches the national "Comprehensive Emission Standard of Air Pollutants" (GB16297-1996). With the implementation of the national "Aluminum Industry Pollutant Discharge Stan...

AI Technical Summary

Problems solved by technology

With the implementation of the national "Aluminum Industry Pollutant Discharge Standard" (GB25465-2010), SO 2 Emission standard from 850mg / m 3 Increased to 200mg / m 3 , and the sulfur content of the carbon anode is difficult to reduce, so that the SO produced by the aluminum electrolytic cell 2 Flue gas is generally discharged beyond the standard, and its treatment has become increasingly urgent, but the current existing technologies cannot cost-effectively carry out low-concentration SO2 in aluminum electrolytic cells. 2 The treatment of flue gas prevents the aluminum electrolysis industry from developing more healthily and sustainably