The Crushing & Grinding Of Gypsum ? Introduction

In the crushing and grinding of metallics for beneficiation, the sizing is normally done to liberate the metals or sulphides for further processing to improve recoveries of the basic metals or minerals. The objective is to reduce the ore in size through various closely controlled stages to that degree of fineness which gives an economic liberation of valuable mineral, but which avoids as much as possible the production of sliming fractions. A different philosophy applies to the crushing and grinding of Gypsum. Our requirements normally demand controlled grinding and/or crushing of the material not only to a fineness suitable for further processing of the mineral into end products, but to produce various sizes of material which are them- selves saleable products. The majority of our tonnage ultimately ends up in stucco for Wallboard. Therefore, our mineral reduction is normally designed toward this end, but it is done in a manner that permits drawing off inter- mediate products to meet various Customer requirements. This forces us into compromises at times in our equipment installations, and our equipment must sometimes be more versatile and complex than we would like it to be. We try to process our basic rock, Gypsum, for the most efficient size reduction. We market 5 to 6 different sizes intermediate to the end product, which generally is the fineness of material to be used for stucco for Wallboard, and we do this with controlled crushing, grinding and sizing cycles of the material. To summarize, we use a different philosophy of crushing and grinding than the metallic field which uses comminution or crushing and grinding to improve recovery, whereas we choose our equipment to crush and grind primarily for product performance.