Method and system for wet dearsenification of smelting flue gas

Abstract

The invention belongs to the technical field of flue gas dearsenification, and particularly relates to a method and a system for wet dearsenification of smelting flue gas. The method for wet dearsenification of smelting flue gas comprises the following steps of: washing the smelting flue gas with high-concentration sulfuric acid so as to remove most of sulfur trioxide; and washing the flue gas washed by the high-concentration sulfuric acid with low-concentration sulfuric acid so as to remove most As2O3; wherein the mass fraction of sulfuric acid in the high-concentration sulfuric acid is 40% or above, and the mass fraction of sulfuric acid in the low-concentration sulfuric acid is 20% or below. The method for wet dearsenification of smelting flue gas has the advantages of small hazardous waste residue amount, low agent consumption, low treatment cost and high purity of main arsenic products.

Description

technical field [0001] The invention belongs to the technical field of arsenic removal from flue gas, and in particular relates to a method and system for wet arsenic removal of smelting flue gas. Background technique [0002] During pyrometallurgy of arsenic-containing metal ore (As%≥0.5%), most of the arsenic in the concentrate enters the flue gas, and this part of arsenic must be removed before the flue gas enters the acid system to avoid adverse effects on subsequent acid production Impact, reduce the amount of waste acid containing arsenic in the flue gas purification system. [0003] At present, there are two types of arsenic removal technologies for non-ferrous smelting flue gas: dry arsenic removal and wet arsenic removal. The dry arsenic collection technology uses the flue gas quenching operation to condense arsenic trioxide into a solid state, and then enters the bag filter to complete the gas-solid separation. Pure As 2 o 3 . The arsenic removal efficiency of ...

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Problems solved by technology

[0004] However, due to the existence of a certain amount of SO in the smelting flue gas 3 , the flue gas dew point temperature is about 200 ℃ higher, which is in the temperature range of the quenching tower, so a large amount of condensed acid and arsenic trioxide condense out in the tower, causing problems such as bag blockage of the dust collector and equipment corrosion

Similar companies generally use the method of spraying alkali solution (NaOH or CaO) in the tower to condense and precipitate As 2 o 3 while removing SO from the flue gas 3 , but they all have problems to varying degrees: Using NaOH to remove SO 3 The cost of reagents is high, and CaO is used to remove SO 3 Then a large amount of calcium sulfate produced is mixed with As 2 o 3 products, reducing the purity of arsenic trioxide products, which brings many difficulties for subsequent treatment, and the cost of hazardous waste treatment is very high

The arsenic removal rate of this process can reach more than 99%, and the wastewater can be discharged up to the standard. The disadvantages are: the first investment cost is high; 65%, a large amount of impurities enter the arsenic sulfide slag, and the subsequent treatment of hazardous waste slag is expensive and difficult

Fourthly, the arsenic sulfide slag produced is hazardous solid waste, the arsenic grade is low, only 30%, the amount of slag is large, and the disposal cost of hazardous waste is high

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