Editor's Note : In China, where the mechanical processing industry, the defense industry, and the metallurgical industry are developing at a high speed, corundum and silicon carbide have an irreplaceable role and strategic significance as abrasives and refractories. However, in today's severely overcapacity, we are facing the choice of survival and development. The three major problems of energy consumption (comprehensive utilization), raw materials and environmental protection are the key to whether the abrasive industry can break through the encirclement, and the first one is environmental protection.
In the abrasive industry in the 1960s, except for the top ten key enterprises, most of them were small and micro enterprises, most of which belonged to the local industrial bureaus, and they all had good economic benefits. With the development of the entire national economy and the transformation of the economic system, the industry has undergone tremendous changes in the past few decades, with a tens of times increase in production capacity and output. But looking at the overall situation, there is not much change in production methods, production techniques, and production equipment. The smelting of corundum and silicon carbide is still the traditional dumping furnace, fixed furnace, electric resistance furnace, etc. The domestic grinding wheel can not replace the high-speed and high-efficiency grinding wheel, and the production methods are mostly semi-mechanized. Today, problems have arisen, the cost of labor has increased rapidly, and large-scale workshop-style production has faced a serious decline in corporate profits. Severe pollution not only makes it difficult to recruit, but the smog and pollution caused by excessive dust emissions has been a concern of the society. Therefore, the current abrasive (refractory) industry should attach great importance to technological development and environmental protection.
According to the experience of long-term work in the abrasive industry, there are several immature opinions and peers:
1. The environmental protection regulations for the abrasive industry should not be too low or too high.
10mg/m3 is an indoor emission concentration that can be accepted by the state according to the national standards of relevant industries. This concentration means that our workers can work without dirty clothes or shoes after working for eight hours in the workshop. The 30mg/m3 outdoor emission standard is a relevant standard in the metallurgical industry. The implementation of this standard can make the chimney not visible to the naked eye. This indicator is not too strict, and can not be lower, but to achieve this standard, corporate investment is quite large, and some even exceed the investment of major equipment.
This standard is only the minimum standard for human beings to survive. As people's quality of life improves, this standard is tightened. Now the World Health Organization's air dust emission standard is 50μg/m3 or less, which is equivalent to Our current external emission concentration standard is 1/600. The sky is public, so it is inevitable that the emission standards are tightened. If the abrasive industry tightens environmental protection standards, it will inevitably face the tolerance of corporate environmental protection investment and the feasibility of technical realization.
Second, boldly and resolutely eliminate backward granulation production methods, the traditional pickling and washing methods using source-side dust-removing abrasive granulation have been replaced by clear-blowing technology, which is the first of our kind in China and has been adopted by advanced countries such as the United States .
China's relevant design institutes have decided not to undertake the design tasks of pickling and washing granulation production lines, which is a sign of progress. Now the country vigorously promotes the dust removal at the source end, that is to say, the dust is removed at the source of the production of dust, and is not brought into the next operation. For example, the dust generated in the crushing process removes the dust in the process, and there is no dust flying during the screening, which is an effective method for improving the environment.
Third, the traditional dust removal method should be re-selected according to the needs of the situation
Ten years ago, water curtain dust removal, electrostatic dust removal, etc., have been a great improvement for enterprises without dust removal facilities, but now because of its low efficiency, it is impossible to meet the new emission standards, and it is impossible to choose the final dust removal. the way. To achieve the standard of 10mg/m3, the purification efficiency must be greater than 95%. The current national standard that can achieve this standard is the bag type dust collector. There are two kinds of bag type dust collectors, namely: bag filter and filter cartridge dust collector. . For example, it is only used for dust removal at around 250 °C. The filter cartridge dust collector can only work normally for a long time below 110 °C. If the temperature of the flue gas is too high, it must be cooled first. However, the filter cartridge dust collector has become a trend in the international development due to its compact structure, long service life and easy maintenance.
Recently, there is data showing that a kind of Coulomb electric dust removal can increase the electrostatic dust removal efficiency by 30% to more than 90%. However, there is no case for whether the abrasive industry can achieve the standard of 10mg/m3.
Fourth, the dust-free system that has not been carefully designed is of poor practicality
From the transition to the environmental protection department inspection to the actual application, the system design cannot be ignored. The dust removal equipment is a system. The dust collection is not only related to the performance of the main body of the equipment, but also closely related to the wind resistance of the pipeline and the position and shape of the collection hood. Therefore, the dust removal system can only be expected after careful design according to the actual situation on site. The effect, especially the high-temperature dust removal of the smelting furnace, should be reduced from below the kiln outlet temperature of about 500 °C to below 120 °C, often using long-distance natural cooling or forced cooling, the wind resistance generated by this system is generated by the dust removal system. Direct impact, so in recent years, many companies to save the investment to build a dust removal system, the final retirement is an example.
V. Comprehensive utilization
At present, enterprises have realized the recovery and utilization of carbon monoxide in the smelting waste gas of silicon carbide. The waste heat utilization of corundum smelting has also been realized by enterprises. At present, the utilization of dust collected during the smelting dust and granulation process of corundum is estimated. It is estimated that there will be result.
Sixth, the industry's environmental difficulties
The environmental conditions for the loading and unloading of silicon carbide smelting are quite poor. How to achieve clean production is a common concern of the peers, and we hope to solve it within the acceptable range of investment.
Conclusion : The abrasive industry is currently being tested in the national environmental remediation process. Now entrepreneurs have realized its importance. It has almost become a prerequisite for survival and development. The only way to solve the problem is to use it now. Mature technology, while making great efforts to improve and innovate the process, so that the production of abrasives is truly clean, efficient and intelligent.
Ningbo Kyson Cool Electronic Technology Co., Ltd. , https://www.kysonrefrigeration.com