Foundry has long been a big polluter of environment. Not only foundry workers have been working in the harsh environment with high intensity, high dust and high noise, but also the residents near the factory have suffered from it. Although casting is an old industry, it has developed rapidly in recent years, and advanced technology and process are constantly applied in practice, but in general, the technology level of this industry is relatively backward , and the factory efficiency is generally poor. In order to avoid increasing the burden on enterprises, many factories discharge smoke from cupola, clean up the dust produced by casting, and directly discharge it to the atmosphere without any treatment, It causes serious pollution to the environment , and the nearby residents are suffering. In recent years, due to the increasing publicity of environmental protection, the increasing awareness of environmental protection of residents, and the increasing enforcement of law on environmental protection by the state, environmental protection supervision departments at all levels have received complaints from residents around the foundry, and even some foundries have been sued by nearby residents, often fined or compensated, seriously affecting the normal production of the foundry, Many foundries also gradually realize the importance of environmental pollution control, and think that only protecting the environment can ensure their own sustainable development. Therefore, they have invested in environmental protection and control, requiring the facilities for dedusting, desulfuration and air purification, in order to achieve the standard emission of smoke and dust, and achieve the double harvest of economic and environmental benefits.
At present, new processes and equipment for flue gas desulfurization and dedusting are emerging in an endless stream , but there is no state-of-the-art process and equipment that are suitable for any occasion, with advantages and disadvantages. Each process has a applicability problem. Only by being familiar with these processes at home and abroad, analyzing their advantages and disadvantages objectively and dialectically, and selecting appropriate processes and equipment reasonably according to local conditions, Only by analyzing and studying the actual situation of each enterprise, according to the comprehensive comparison of environmental protection performance and economic performance, can we make a more optimized choice.
Based on the actual situation of a famous diesel engine foundry in China, this paper briefly discusses the impact of sand casting on the environment, and the process equipment and selection principle applicable to the environmental pollution control of foundry. The process and equipment of cupola flue gas desulfurization and dust removal and dust removal in the cleaning room are mainly introduced.
The production equipment of foundry is easy to cause air pollution and noise pollution. The main equipment causing pollution is introduced in detail below.
1. Air pollution from cupola
At present, cupola is used in most of the foundry for molten iron. Apart from a spark catcher, cupola has no other dedusting equipment. The fuel of cupola is mainly coke. The sulfur content of coke currently used in China is relatively high, The flue gas produced by cupola has the following characteristics: large amount of flue gas, large amount of dust, high content of sulfur dioxide, high flying dust and large pollution area.
This enterprise uses four 5 t / h hot blast cupola, two of which are used in turn every day, and their pollutant producing parameters are :
(1) Exhaust gas composition:
Containing dust, sulfur dioxide and other harmful substances;
(2) Flue gas temperature:
(3) Dust concentration:
(4) Flue gas volume:
2. Air pollution caused by sand treatment equipment
The molding sand for casting needs to contain about 3% pulverized coal. Therefore, pulverized coal should be added in the mixing process of new sand. After casting, sand dropping, crushing, screening, lifting, transportation and other processes should be carried out. Since the moisture of molding sand has evaporated after casting, each of the above links is a dust raising process, especially crushing and screening, with a dust concentration of 2000-3000 mg / m3, The main pollution component is pulverized coal, sometimes flying everywhere with the wind, seriously polluting the surrounding environment.
3. Clean the air pollution caused by roller
There is also a serious air pollution in the foundry production, which is the cleaning equipment of the foundry. After the casting is put into the blast cleaning drum, it is shot peened and rolled, which produces a large number of iron containing dust and seriously pollutes the air. Workers work in such an environment for a long time and are prone to pneumoconiosis and other occupational diseases.
4. Noise pollution caused by mechanical equipment
Noise is also a major pollution of the foundry to the environment. In the past, the enterprise opened two Cupola for more than 10 hours every day, two 75 kW / h large blower fans and two 20 m3 air compressors to produce continuous noise. In addition, three production lines, six molding machines and three sand Shakers made continuous noise. In normal production, 70-80 decibels and the maximum noise is more than 100 decibels, If you work in this environment for a long time, the noise will cause great harm to the human body.