How to realize environmental protection in sand and stone production process? Usually, our sand aggregate production will adopt the dry sand process with little impact on the environment. This method saves water, because the water consumption of dry sand is very small, and there is basically no water except for spray dust reduction. However, no matter what kind of production process is used, it should be carried out under the premise of environmental protection.
Dry production means that water is basically not used in the whole production line, except that water is used for spray dust removal in some process links. This process is mostly used in northern China, while semi dry production is mostly used in southern China, that is, there is no water used in the crushing and pre crushing process, and sand washer water is used in the crushing and screening process. Under the premise of meeting the technical requirements of concrete aggregate, the dry production process with relatively light environmental impact should be selected as far as possible for the design of sand and gravel processing process.
1. Environmental protection design in dry sand making process.
The dry sand making process of artificial aggregate generally adopts the modes of coarse crushing, medium crushing and fine crushing. The sand making machine equipment selected in the dry sand making process is the vertical shaft impact crusher, which requires the feed particle size to be less than 50mm. After two-stage crushing, the sand and stone with particle size less than 50mm can be directly entered into the sand making machine, which simplifies the process flow. In order to reduce the noise and dust of dry production, sand and gravel processing plants will adopt full dry production in order to meet the environmental protection requirements. The whole production line is fully sealed, and the generated dust is recycled by fans and dust collectors, and screened by screening equipment. This kind of sand and gravel processing system can consider using full sealing and environmental protection for crushing and screening equipment.
2. Environmental protection design in wet sand making process.
If the wet mode is adopted in the wet production of sand and gravel, the water content of sand is required to be relatively high, generally about 15%, which will affect the mix proportion of concrete to a certain extent, but it will bring difficulties to the production of cushion materials, because the water content of finished sand cushion materials is about 3%. At present, some practices mainly adopt the mixing and adjustment process, washing the screen surface with water and stone washing process. The semi-finished sand is first washed with wheel sand washing machine or spiral sand washing machine to remove the excess stone powder or soil, but a large number of useful fine particles are lost in the washing process. In order to reduce the external discharge of stone powder, these particles can be recycled. When selecting the wet production process, we must adopt a reasonable wastewater treatment process to treat the wastewater The waste residue shall be comprehensively utilized to turn waste into treasure, and the disposal of waste residue shall be minimized to meet the requirements of environmental protection.
In terms of the implementation of various production projects at present, with the continuous improvement of production equipment and process, the dry aggregate production system is mainly used in construction, water conservancy and hydropower projects and other industries. Combined with the advantages and disadvantages of dry and wet method, the implementation effect of semi-dry sand making process in nuclear power plants is obvious. Environmental friendly sand and gravel aggregate is required by various projects, and enterprises should implement it in combination with specific conditions.
