Dry Grinding

Abstract

Though most ores are reduced by wet grinding before being processed, some can better be ground and treated dry. Many minerals and synthetic substances require size reduction only. Other grinding problems arise in which chemical instability, contamination, corrosion or risk of explosion call for special precautions, such as milling in an inert atmosphere or one where moisture is undesirable or must be removed. In an arid country the chronic shortage of water may dictate the use of dry grinding methods. Where a dry end-product is called for and can be processed up to the required state without the use of water, dry grinding is to be preferred. Among the raw materials thus treated are asbestos rock and “crudy”, coal for powdered fuel, cement clinker, talc, metal powders, drugs, and chemical salts. In addition to open and closed-circuit grinding, batch treatment is frequently used. In this method, grinding media and feed are loaded into the grinding mill and worked dry until the desired state of attrition has been achieved. The product is then discharged.