The types of electroplating exhaust gas mainly include hydrogen chloride, chromic acid mist, sulfuric acid mist, nitrogen oxides, hydrogen cyanide, etc., as well as some dust gas and alkaline gas, harmful to the environment. At present, the most commonly used methods of governance are to start with the optimization of the source technology on the one hand, and to install professional purification equipment and exhaust systems on the other hand, which must be comprehensively considered and co-ordinated.
Source control + end purification to achieve efficient treatment of electroplating exhaust
Electroplating enterprises in the production process, will produce wastewater, waste gas, waste residue, commonly known as "industrial waste." Waste management has always been the top priority for environmental inspection work. Compared with the control of solid waste such as waste water and waste residue, the monitoring and treatment of waste gas are more difficult and have more problems. This article from the electroplating process design point of view, lists the technical problems of electroplating exhaust treatment, and put forward the corresponding solutions for reference purposes only.
First, electroplating exhaust on the environment, human body and other great harm
According to "electroplating pollutant discharge standards) GB21900-2008, electroplating exhaust gas types are mainly hydrogen chloride, chromic acid mist, sulfuric acid mist, nitrogen oxides, hydrogen cyanide and fluoride. In addition, there are some dust gas, organic waste gas, alkaline gas.
Electroplating waste gas on the environment, the great harm to human body, and the harmfulness of electroplating exhaust gas analysis is precisely the premise and foundation of electroplating exhaust gas treatment.
Plating exhaust on the human body hazards, mainly in the human respiratory tract, eyes, skin hazards, some electroplating exhaust colorless, odorless, long-term chronic respiratory damage, after gradual accumulation, content exceeds the limit, can lead to bronchitis, bronchial asthma , Lung cancer, liver cancer and other diseases. The electroplating process of hydrogen chloride, acid fog, etc. will have human eye and skin irritation, there will be pink eye, dermatitis and other symptoms.
Electroplating waste gases are also harmful to plants and buildings. Sulfur dioxide and nitrogen oxides emitted from electroplating processes are harmful to the growth of plants in the air and even kill plants. If you form another acid rain, but also on the building corrosion, rust oil and so on.
In addition, electroplating exhaust gas is also harmful to the electroplating products, such as electric shop, acid fog, dust and so on, will have varying degrees of impact on the purity of electrochromic equipment and electroplating materials.
Second, the comprehensive management of electroplating waste gas technology
According to "Electroplating Pollutant Emission Standards" (GB21900-2008), the electroplating hook process and facilities must be installed local gas collection system, and centralized purification control, in order to be unified by the exhaust pipe into the atmosphere. This can be electroplating exhaust through three ways to deal with, respectively, for the source to reduce electroplating exhaust, installation of exhaust systems, installation of electroplating exhaust gas purification equipment.
(A) to reduce the source of electroplating exhaust
By changing the process of electroplating industry production, or the use of non-toxic materials, the electroplating process to achieve zero emissions of toxic and hazardous waste purposes.
In the electroplating process, the plating parts cleaning, the use of alkali wash oil, pickling rust, cleaning solution were added to the acid mist, alkali mist inhibitor, can effectively reduce the acid mist, alkali fog emissions.
Chromium fog suppression, you can use low-temperature equipment or low-temperature process, while adding less plating solution perfluoroalkyl ether sulfonate, and pay attention to the allocation of perfluorinated ether sulfonate method and the ratio can be Effectively inhibit the generation of chromium fog. In addition, the surface can also be plated Ming tank, covered with a layer of polyethylene, PVC hollow ball, but also can effectively inhibit the release of chromium fog.
Inhibition of nitrogen oxides, the inhibition of nitrogen oxide emissions in the plating process, you can use non-nitric acid plating process, such as electroplating of aluminum, the use of sulfuric acid and phosphoric acid, then add a small amount of additives, you can aluminum parts polishing. On the other hand, nitrous acid is oxidized to nitric acid by chemical oxidation and chemical reduction, or nitrogen oxide gas is reduced to a non-toxic inert gas.
(B) install the exhaust system and purification system
Considering the treatment of electroplating exhaust gas, exhaust gas can be installed to transport the contaminated exhaust gas to the gas purification system so as to remove toxic and harmful gases. This shows that the installation of exhaust systems and purification systems, is a unified whole.
According to the characteristics of electroplating exhaust emissions, factory floor production conditions and harmful emissions, using different exhaust systems. As in the workshop, the general is because the source is not fixed, more emissions and other factors, the use of local exhaust mode. These local exhaust gas monitoring, if the emission standards can be directly discharged into the atmosphere, if it is higher than the emission standards, you need to pass the exhaust gas purification system, the point of harmful waste emissions, the exhaust gas collection, After venting to the outdoor system. In order to ensure the balance of the air pressure in the workshop, mechanical ventilation is also required to keep the indoor air quality in line with the standards.
Acid gas purification, mainly acidic waste gas with three alkali spray, and then discharged by the chimney. When absorbing acid flue gas by the method, a sealed cover is installed on the vacuum pump chest to discharge the gas in the workshop into the spray tower filled with the filler. The process to remove acid waste gas efficiency up to 90%.
Third, electroplating exhaust gas treatment technology problems and solutions
Electroplating exhaust gas treatment must be considered, co-ordinate treatment, in order to achieve the removal effect. However, due to the characteristics of high pollution and high energy consumption in the electroplating industry, there are many kinds of exhaust gas and the treatment methods are different, and the electroplating exhaust gas is not collected completely. Therefore, there are problems that need to be solved urgently in the electroplating exhaust gas treatment.
According to the existing problems of electroplating exhaust gas treatment technology, put forward corresponding countermeasures:
First, we can change the point collection in the workshop into a combination of point collection and surface collection. That is, we set up a collection device for pollution discharge at the discharge point of key pollutants, and collect the surface of the entire workshop to ensure the pollution in the workshop air Material concentration did not exceed the limit.
Second, we can synthesize a kind of absorbing liquid that can absorb all the exhaust gas at the same time, or study a set of integrated absorption process to ensure the characteristics of the spray liquor such as acid-base waste gas, chromium fog, cyanide and nitrogen oxide All the exhaust gas in electroplating production is absorbed and purified.
Third, the source control, optimize plating design process, reduce pollutants
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