A method for treating arsenic-containing polluted acid wastewater produced by smelting flue gas

Abstract

The invention relates to a treatment method of arsenium-containing polluted acid wastewater generated by smelting flue gas, which comprises the following steps: pretreatment for sulfate removal; preneutralization; primary neutralization; secondary neutralization; tertiary neutralization; and circulating treatment. The pretreatment for sulfate removal, preneutralization and primary neutralization are sequentially operated to remove the sulfates and fluorine in the system in the precipitation form, wherein the removal rate is up to 95% or above, and the precipitate arsenium content is less than 0.1%. The secondary neutralization can enable more than 85% of the Cu, Fe, Pb, Zn and other metals to form a hydroxide precipitate, so that the high-content metals can be recycled. The tertiary neutralization can enable more than 95% of As to be enriched in the filter residue in the forms of calcium arsenate and calcium arsenite and to be recycled. The method can not generate unmanageable neutralization slag to form secondary pollution, and uses fewer reagents in the whole process; the calcium chloride only needs to be purchased at the time of starting; the operating process can be satisfied by circulation; and the method only consumes small amounts of lime and flocculant, is simple to operate, and has the advantages of low cost and favorable treatment effect.

Description

technical field [0001] The invention belongs to the technical field of wastewater treatment, and in particular relates to a method for treating arsenic-containing polluted acid wastewater produced by smelting flue gas. Background technique [0002] On October 1, 2007, the State Environmental Protection Administration and the State Administration of Quality Supervision, Inspection and Quarantine jointly promulgated the "Identification of Hazardous Waste Identification Standards for Toxic Substance Content" (GB 5085.6-2007). According to relevant laws and regulations, this standard has the effect of mandatory execution. The standard clearly stipulates that when the total mass fraction of one or more highly toxic substances or carcinogens in solid waste is greater than or equal to 0.1%, the solid waste is classified as hazardous waste and must be managed as hazardous waste according to law. [0003] The acid wastewater produced by washing copper smelting flue gas contains a la...

AI Technical Summary

Problems solved by technology

[0004] Lime-iron salt method and sulfidation method are mostly used in smelters to treat arsenic-containing wastewater. The amount of raw materials and slag in the lime-iron salt method is very large, which makes material transportation difficult; the limestone pretreatment equipment is huge, occupies a large area, and the investment is high. Poor; complex process, huge equipment, high cost of neutralization and anti-neutralization, large consumption of flocculants; valuable metals in slag are depleted and cannot be recovered, resulting in waste of resources; the main component of neutralized slag after dehydration is gypsum And iron arsenic salt, containing other heavy metal basic salts (Cu(OH)2, Zn(OH)2, etc.), at the current stage, it is difficult to recover the useful metals in it, and the production cost is high. In order not to cause secondary pollution, it must Properly dispose of the neutralized slag, which is usually landfilled in a permanent slag site (according to national regulations, the slag is a hazardous waste); the effluent water quality is not easy to control to meet the standard, the floc settlement performance is poor, the clear liquid is easy to return to muddy, and the effluent is high-content Salt water cannot be reused; the treatment cost is high, and the treatment cost per ton of water is about 90 yuan

The vulcanization method is an effective method to recover and treat arsenic-containing wastewater, but the equipment is huge and occupies a large area; the pH value is adjusted repeatedly, the consumption of chemicals is large, and the treatment cost is high; there are many control indicators and difficult to operate and adjust; in order to ensure the heavy metal The removal rate often needs to add excessive sulfide. Excessive sulfide will generate hydrogen sulfide gas under acidic conditions, which is easy to cause secondary pollution. Hydrogen sulfide gas is highly toxic and easy to cause personal injury to field operators; the generated The heavy metal sulfides are very fine and difficult to separate from the liquid phase; the sludge particles are fine and difficult to dewater; the treated slag and water cannot be recycled and completely discarded, resulting in waste of resources; the treatment cost is high

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