What is the effective amount of pulverized coal in sand molding machine?
The amount of sand molding machine's effective coal powder that should be present in cast iron sand varies depending on factors such as casting size and thickness, casting temperature, surface sand or single sand. For example, the amount of effective coal powder in the high-density molding sand using ordinary pulverized coal is 5 to 7%, and the effective coal powder amount using the higher-quality coal powder can be reduced to 4 to 5%. If high-efficiency coal powder is used, only 3 ~4% can be. At present, the quality of coal powder sold and supplied in different parts of China is quite different. Some coal powders contain a lot of impurities and low gas generation. The amount of gas generated by high-density modeling sand should be 14~30ml. For example, the static pressure line sand of a joint venture in Tianjin is 16ml, and the box injection line is <15ml. Some molding sands also contain starch-based materials or mixed with broken core sands, which also act as anti-sanding and gas, and can be considered together with coal powder. It should also be noted that individual pulverized coal is made from gas or long flame coal with a relatively high volatile content. Although the amount of gas generated by the molding sand is high, the anti-sticking ability is poor, and the casting is prone to void defects. Therefore, the method of controlling the amount of effective coal powder in the sand and the old sand by the gas generation amount is suitable for the coal powder in the range of 28 to 35% of volatile matter and ≤10% by mass of ash.
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