Date: Jan. 04, 2021
As a resource-dependent building materials industry, the silica sand washing process is related to the future development of the industry. Therefore, it is urgent to solve environmental problems. In the process of silica sand washing, there are mainly pollution problems such as dust, noise, and wastewater, and relevant discussions should be conducted on these issues to promote the green development of the machine-made sand industry.
In the silica sand washing process, dust control mainly includes two methods: dust suppression and dust removal. During the production process of sand and gravel aggregates, dust is mainly divided into organized dust and unorganized dust.
Organized dust is mainly produced in the process of silica sand washing, crushing, screening, and transportation. For the treatment of organized dust, dust suppression should be carried out first. Through optimized design, the generation of dust during the production process is reduced, and the subsequent dust treatment load is effectively reduced, and investment is saved. Improve efficiency.
At the connection between each silica sand washing process, the appropriate blanking pipe and the appropriate inclination angle should be selected to reduce the drop of the blanking point and the impact on the equipment.
The belt transportation should be closed to prevent dust from overflowing, and the belt conveyor speed should be reasonably controlled to reduce the generation of dust. At the same time, efficient suction and dust collection devices should be installed at each unloading point.
Spray humidification of the aggregates on the vibrating screen can reduce secondary dust pollution and make the amount of organized dust lower than the dust emission standard of 20mg/m3.
The crushing workshop is sealed and isolated to prevent dust from overflowing. At the same time, in the silica sand washing process, dust collection equipment is installed above the workshop to exhaust dust.
The generation of unorganized dust mainly occurs in the process of mining, shed storage, and finished product shipment. Because these places have large space areas, it is not suitable to use ventilation and dust removal methods, so other reasonable dust removal measures should be adopted.
In the silica sand washing process for the treatment of mine dust, advanced blasting technology should be used to reduce the fine ore rate and dust height. At the same time, spray devices are used to wet the blasting area and green the mines after mining to achieve a true green mine.
The storage shed adopts a fully enclosed storage method, and multiple spray humidification and dust removal devices are installed above the shed to effectively reduce dust. For the dust generated during the shipping of finished products, due to the incomplete separation of stone powder and aggregate during the production process, some stone powder will adhere to the surface of the aggregate, which will cause dust pollution during the transportation process. In the silica sand washing process, to avoid this situation, you can The finished aggregate is screened and washed, and the wet production process is adopted, which can not only solve the dust pollution during transportation but also remove the stone powder and mud powder on the surface of the finished product and improve the product quality.
In the silica sand washing process, the noise source in the plant area is mainly the crushing and screening workshop of machine-made sand and gravel aggregates and the dust collecting fan. The control of noise pollution should mainly be controlled from the sound source and the transmission route.
First of all, we should update the obsolete equipment, choose some advanced technology equipment that produces less noise, such as replacing the metal screen with a polyurethane screen, installing a muffler, sound insulation cover or reducing the vibration of the fan and other noise reduction measures, from the root cause Reduce noise. Secondly, the workshop should be closed and soundproofed as much as possible, and at the same time, the plant area should be greened to block the spread of some noise. If employees need to work in the workshop, they must also take labor protection measures. They should wear earplugs, earmuffs, etc. to ensure the health of the workers on the job.
In the silica sand washing process, there are two main types of sand and gravel aggregate production lines: dry and wet. Although dry production has no wastewater, dust pollution is difficult to control, and it is impossible to remove the stone powder and mud powder attached to the surface of the finished aggregate, which affects the quality of the product. As a high-quality sand and gravel aggregate production line, it is necessary to solve the problem of stone powder and mud powder attached to the surface of the product and improve the product quality. Therefore, the product needs to be screened and washed, but wastewater is also generated.
In the silica sand washing process, traditional sand and gravel aggregate wastewater treatment is mainly natural sedimentation or flocculation sedimentation method. Most of the sedimented mud is processed by the natural dehydration method. This method takes a long time and depends on weather conditions. In the case of the flood season, If the sedimentation tank is not treated in time, it will cause wastewater to overflow outside the tank and into the surrounding waters, causing pollution to the surrounding environment. Therefore, a new process with a higher degree of automation is required.
First, the wastewater is pretreated with a high-efficiency cyclone and a dewatering screen, and the larger particles of sand are quickly separated for recycling, and then the pretreated wastewater enters the thickener for concentration and then passes through the thickened slurry to a certain concentration. The combined technology of radial-flow sedimentation tank, belt filter press, and the ceramic filter is used for mechanical dewatering to separate the sedimentation slurry. This method is fast and efficient, has a high degree of automation, saves land area, and can reduce operating costs, and the mud is convenient Collection and centralized treatment will not cause secondary dust pollution due to natural air drying. The treated wastewater will be recycled to achieve a “zero” discharge of industrial water.
Compared with previous processes, this wastewater treatment process can improve the automation level, shorten the dehydration time, and enable the wastewater treatment to be continuously and efficiently performed in the silica sand washing process.
Under the high pressure of environmental protection, equipment manufacturers have launched intensive and environmentally-friendly machine-made sand production equipment. Sand and gravel enterprises should choose efficient and reliable treatment plans based on the current level of production technology development, to promote the healthy development of the sand and aggregate industry in the silica sand washing process.
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