Electroplating waste gas treatment technology and its existing problems and countermeasures

Plating companies produce many types of pollutants, containing heavy metals and various harmful chemicals in the sewage, but also a lot of toxic emissions. These exhaust gases, if not taken measures to deal with, will pollute humans and the environment. Based on many years of electroplating process design experience, I put forward some suggestions and measures for the treatment of electroplating exhaust gas, and provide technical reference for the exhaust gas treatment in the electroplating industry. It is also of great significance for the protection of the ecological environment and the control of air pollution.

1 electroplating exhaust gas concept

1.1 plating exhaust gas types

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, alkali gas.

1.2 electroplating exhaust hazards

According to the monitoring of electroplating exhaust gas, analysis of the type of exhaust gas, it is not difficult to find that these exhaust gas are extremely harmful to the human body. To manage these exhaust gas well, we must analyze the harm of the electroplating exhaust gas to the environment.

1 on the human body hazards, mainly in the human respiratory, eye, 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.

2 hazards to plants and buildings, sulfur dioxide emitted by electroplating process, nitrogen oxides, harmful to the growth of plants in the air, and even kill plants. If the formation of acid rain will corrode the building, embroidered oil and so on.

In addition to the above hazards, in the plating process, the resulting plating waste will be harmful to the electroplating products. Mainly because of the shop in the decontamination, acid-base fog, dust and so on, will be on the shop to the trace equipment and electroplating material purity can have varying degrees of impact.

2 plating exhaust gas treatment methods

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.

2.1 source to reduce 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.

1 in the plating process, the plating parts washing, called investment cast alkaline degreasing, pickling remove embroidery, therefore, in the cleaning solution were added acid mist, alkali mist inhibitor, can effectively reduce the acid mist, alkali fog Emissions. 2 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. 3 nitrogen oxides inhibition, inhibition of nitrogen oxide emissions in the plating process, you can use non-nitric acid plating process, such as electroplating 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, the chemical oxidation and the chemical reduction are used to oxidize nitrous acid to nitric acid or to reduce nitrogen oxide gas to a non-toxic inert gas.

2.2 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.

2.2.1 installation exhaust system cnelcPage]

According to the characteristics of electroplating exhaust emissions, factory production constraints, harmful exhaust emissions, the use of 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.

2.2.2 Exhaust gas purification system

In the treatment of acid waste gas, the main method of purifying acid waste gas is to spray the acidic waste gas with tertiary alkali liquor and discharge the chimney. Such as dealing with the typical acid to the exhaust of the lye configuration shown in Table 1. 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%.

3 electroplating exhaust gas treatment technology problems and solutions

3.1 electroplating exhaust gas treatment technology problems

Electroplating industry is heavily polluting industries, not only the exhaust gas pollution, there are other such as water pollution, sludge pollution, noise pollution, the governance of these pollutants must be comprehensively considered and co-ordinated in order to achieve the removal effect. It is also due to electroplating industry, high pollution, high energy consumption and other characteristics of the exhaust gas treatment there are still some blind spots, such as exhaust gas collection, and workshop collection of exhaust gas is not complete, at present a lot of exhaust gas collection devices installed in the exhaust gas release, That is, point installation; In addition, due to the variety of exhaust gas, treatment methods vary, therefore, can not be done in the treatment of all the exhaust removed. These are the urgent problems to be solved in the current electroplating industry.

3.2 electroplating exhaust gas treatment technology to solve the problem

According to the problems existing in the electroplating exhaust gas treatment technology, the corresponding countermeasures are put forward. First, the point collection in the workshop can be changed to a combination of point collection and surface collection, that is, the collection of pollutant gas collection devices for discharge of key pollutants, The entire workshop is also set up surface collection, to ensure that the workshop air pollutant concentration does not exceed the limit; second, can be integrated acid-base exhaust gas, chromium fog, cyanide, nitrogen oxides and other spray liquid characteristics, prepared a Absorption of all kinds of exhaust gases can be absorbed at the same time, or study a set of comprehensive absorption of the process to ensure that all the exhaust gas in the plating process are absorbed and purified.

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