During the production and processing of a metal surface treatment company, there are several processes that produce organic waste gas. These organic waste gas needs to be treated before they can be discharged, because if they are directly discharged into the air, they will seriously endanger human health and pollute the environment.
According to the requirements of relevant national and local environmental protection laws and regulations, as well as the approval opinions of the local Environmental Protection Bureau for the project, the waste gas discharged from the factory during the production process is effectively treated to make it meet the national and local waste gas emission standards.
Determination of hexavalent chromium waste gas treatment process
Hexavalent chromium tank (passivation) waste gas treatment: the main raw material is chromic anhydride, which is collected by a side suction hood, and the treatment process: it is recovered by a “mesh chromic acid mist purifier”. Its working principle is agglomeration, that is, when the chromic acid mist passes through the filter grid made of multi-layer Plastic mesh, it will condense into liquid due to obstruction, and then let the condensed liquid gradually flow into the recovery container and then discharge it. Back to the passivation tank, the efficiency of this purifier is above 98%. The remaining chromic acid mist residue is removed through the “acid spray tower”. Adopt NaOH solution to absorb.
Determination of hydrogen cyanide waste gas treatment process
Waste gas containing hydrogen cyanide-electroplating with cyanide-containing bath, the cyanide-containing gas produced is collected by a suspended ceiling suction hood. The treatment process: directly absorbed by a spray packing tower, and the absorption liquid is sodium hypochlorite solution.
Determination of acid-base waste gas treatment process
Acid and alkali waste gas-during the cleaning process of the acid electroplating tank, the volatilized hydrochloric acid, sulfuric acid, etc., these particles disperse with the air flow to form acid mist, which is collected by the ceiling suction hood. The treatment process: directly adopts the spray packing tower to absorb, The absorption liquid is soda lye.
Removal efficiency analysis
A. The recovery efficiency of chromic acid mist in the “net-type chromic acid mist purifier” is above 98%, and the acidic waste gas is absorbed in the spray absorption tower, and the removal efficiency can reach more than 99.6%;
B. Sulfuric acid mist and hydrochloric acid mist are absorbed in the spray absorption tower, and the reaction speed is fast, but the pH value must be controlled above 9, and the removal efficiency can reach 98.0% or more.
C. Hydrogen cyanide is absorbed in the spray absorption tower, and the absorption speed is fast, but it will produce secondary volatilization, so the cyanide breaking reaction must be controlled to control the cyanide breaking effect, and the removal efficiency can reach more than 98.0%.
Based on the above, we decided to directly adopt the acid mist purification tower for absorption, and the absorption liquid is sodium hypochlorite solution.
Link to this article： Non-ferrous metal waste gas treatment plan
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