Method for removing heavy metals from high-concentration cyanide-containing wastewater in gold production through cyanide breaking

Abstract

The invention relates to a method for removing heavy metals from high-concentration cyanide-containing wastewater in gold production through cyanide breaking, and belongs to the technical field of cyanide-containing wastewater treatment. The method comprises the following steps: S1, flocculent precipitation; S2, electrolysis; S3, primary natural precipitation; S4, primary cyanide breaking; S5, secondary natural precipitation; S6, iron removal; S7, secondary cyanide breaking; and S8, precipitation treatment. Heavy metal solids generated in the electrolysis process can be separated through one-time precipitation, so recovery treatment of heavy metal is facilitated; a third supernatant is subjected to iron removal treatment by using an iron removal catalyst after secondary precipitation, so that the iron element in the cyanide-containing wastewater can be effectively removed, and the pollution load of subsequent secondary cyanide breaking treatment is reduced; and CN<-> which is not treated by primary cyanide breaking can be further removed by adopting secondary cyanide breaking, so that the difficulty of subsequent treatment is reduced. Compared with other methods for removing cyanogen and removing heavy metals, the method has the advantages of being simple and feasible, stable in reaction process and free of secondary pollution.

Description

technical field [0001] The invention relates to the technical field of cyanide-containing wastewater treatment, in particular to a method for breaking cyanide and removing heavy metals from high-concentration cyanide-containing wastewater in gold production. Background technique [0002] Cyanide-containing wastewater is generated during the gold production process, and the cyanide-containing wastewater usually carries heavy metals, especially gold and silver, which are easily discharged along with the wastewater, causing waste of resources. [0003] At present, the main methods for treating high-concentration cyanide-containing waste liquid produced in the gold production process at home and abroad include chlorination, acidification, sulfur dioxide-air oxidation, activated carbon adsorption and precipitation. There are following disadvantages respectively: [0004] The disadvantages of the chlorination method are: 1. If the equipment is not well sealed during the wastewate...

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Problems solved by technology

[0004] The disadvantages of the chlorination method are: 1. If the equipment is not well sealed during the wastewater treatment process, CNCI (cyanogen chloride) will escape into the air and easily pollute the operating environment; 2. Ferrocyanide complexes and ferricyanide complexes cannot be destroyed The cyanide in the solution cannot be removed by forming precipitates, so the total cyanide is relatively high, especially when dealing with the lean liquid of the gold concentrate cyanide plant, because the lean liquid contains high iron, it is difficult to reduce the released cyanide to 0.5 Below mg / L, the total cyanide content is higher; 3. When bleaching powder or bleaching powder is used to treat high-concentration cyanide-containing wastewater, due to the large dosage, the high concentration of chloride ions in the wastewater will form complexes with copper to make the copper exceed the standard

[0005] The disadvantages of the sulfur dioxide-air oxidation method are: one, the sulfur cyanide in the waste water cannot be eliminated, and when treating the waste water containing the sulfur cyanide, the residual toxicity of the waste water is still relatively large; two, the copper ion at the discharge port of the workshop exceeds the standard; The method of destroying cyanide has no economic benefits, and precious metals and heavy metals in wastewater cannot be recovered

[0006] The disadvantages of the acidification method are: 1. When the cyanide concentration is low, the treatment cost is too high; 2. The wastewater treated by the acidification recovery method needs to be treated twice before it can be discharged; - It cannot be completely removed, so the COD may be high, and the COD of the external drainage may exceed the standard; 4. SO 4 2- The ion concentration is higher, if the SO 4 2- There are special requirements for discharge, and the waste water should be further treated

[0007] The disadvantages of the activated carbon method are: 1. It can only treat clarified water, but not waste water and ore pulp with more impurities; 2. The treatment effect of high-concentration cyanide-containing heavy metals is not good.

[0008] At present, the chlorination method, acidification method, sulfur dioxide-air oxidation method, activated carbon adsorption method and precipitation method cannot effectively remove or recover heavy metals in cyanide-containing wastewater, and there are problems of waste of resources and high energy consumption.