Silicon powder processing refers to the process of crushing smelted silicon blocks (25-80mm) through a special process to produce silicon powder with a specified particle size (usually 80-400μm). At present, there are mainly two types of silicon powder processing equipment in silicon powder factories: vertical mill and rotary mill. Today, this article will introduce the comparison between vertical mill and rotary mill for silicon powder factory equipment.
1. Comparison of production capacity between vertical mill and rotary mill in silicon powder plant: Under the design and calibration production capacity of a 5t/h vertical mill in a company, it can exceed the design capacity by about 5%. Especially in the case of average particle size > 130um, the production capacity can be higher than that. The φ880 rotary mill has a theoretical production capacity of 1.5t/h. However, due to the particularity of the silicon block, the wear of the cutter head of the rotary grinding, the service cycle and other transmission equipment failures will affect the actual production capacity and start-up time of the rotary grinding.
2. Comparison of fine silicon powder content between vertical mill and rotary mill of 325 mesh or above in silicon powder factory equipment: When the vertical mill system operates normally, the content of fine silicon powder can be controlled at about 3%. In the case of long production time and severe grinding roller wear, the proportion of fine silicon powder can be controlled below 8% (the high or low fine powder rate is directly related to the operation control); according to the production data of the φ600 model of a rotary mill in a certain factory, the proportion of 325 mesh or more can reach 10%~15%. According to previous knowledge, the actual production process of rotary milling may exceed this value.
3. Comparison of process design between vertical mill and rotary mill system of silicon powder factory equipment: the vertical mill silicon powder production system adopts negative pressure production, air volume is recycled, the continuity is better, and the system design is more reasonable. Through nearly 10 years of actual use and continuous improvement, the silicon powder processing technology has been improved, which has improved the operation and automation of the vertical mill, and the adjustability is more convenient and reliable. The silicon powder processing system of punching and rotary grinding, because it is conveyed under positive pressure, the sealing condition of the system is not good, the leakage of silicon dust is relatively large, and the continuity is poor, which needs to be improved. Moreover, the overall design is relatively small, with poor cushioning capacity, and cannot well meet the requirements of large-scale silicon powder production. The overall design of the punching and spinning silicon powder processing system is relatively simple and rough, and some dust removal measures are not perfect, so it can only be used by some relatively small silicon powder processing enterprises.
4. Comparison of safety and environmental performance between vertical mill and rotary mill in silicon powder factory equipment: The overall design of the silicon powder processing system of the vertical mill is relatively reasonable, and the technology of winnowing the particle size of silicon powder is adopted. In the process of winnowing the silicon powder, the outlet pipeline of the vertical mill, the cyclone separator, and the bag dust collector are all operated under negative pressure, so the leakage rate of the silicon powder dust is very small. The dust concentration inside the workshop of the silicon powder processing device is very low. Due to the adoption of winnowing technology, the content of fine silicon powder (aerosol) inside the silicon powder production system can be greatly reduced, and at the same time, it can prevent the local deposition of silicon powder dust inside the equipment, and eliminate the possibility of dust explosion inside the silicon powder processing system. The winnowing system of the grinding system is a circulation loop, and the pulse blowback nitrogen of the bag filter is used to replenish the inside of the grinding pipeline, and the grinding system can realize nitrogen protection operation with a small amount of nitrogen consumption. Due to the relatively small and relatively simple design of the rotary grinding silicon powder production system, air separation is not used, resulting in serious silicon dust leakage. The dust concentration at the silicon fume production site is relatively high, which can easily lead to pneumoconiosis among employees. Because the rotary mill silicon powder production system cannot form a closed nitrogen gas sealing system, it is easy to cause silicon dust to accumulate inside the system, so that the content of silicon dust (aerosol) in the rotary mill or other locations is high, and silicon dust explosion is very easy to occur when the fire source energy is high.
6. The comparison of the maintenance situation of the vertical mill and the rotary mill of the equipment in the silicon powder factory: the vertical mill is generally inspected once a month, and the inspection time is 2 working days, and the total maintenance man-day is 8 to 12. The cycle of punching and rotating grinding inspection and replacement of cutter head and liner is<24h. When the quality of the cutter head and liner is not good, it can only be used for 3h~4h and needs to be replaced once. It is estimated that each overhaul will take 0.5 working days, and the total man-days for overhaul will be about 2 man-days, which will not only increase labor costs, but also delay production progress.
Conclusion: Through the comparison and analysis of the vertical mill system and the rotary mill system, as well as the communication with the technicians in the organic (polycrystalline) silicon industry, the general opinion is that the rotary mill is not suitable for large-scale silicon powder processing. In addition, judging from the selection of mills by domestic organic (polycrystalline) silicon manufacturers, although the primary investment of vertical mills may be higher than that of rotary mills, vertical mills are still the ideal choice for most organic silicon (polycrystalline) manufacturers to process silicon powder. Guilin Hongcheng is a manufacturer of vertical grinding mills for silicon powder factory equipment. The HLM silicon powder vertical mills we produce have been widely used and recognized in the silicon powder factory industry. If you have purchase needs for vertical mills for silicon powder factory equipment, please leave us a message for more information about the equipment.