Precipitation from solution is another preparation method used for new ceramics. In the typical the desired ceramic compound is dissolved from the starting mineral, thus permitting impurities to be filtered out. An intermediate compound is then precipitated from solution, which is converted into the desired compound by heating. An example of the precipitation method is the Bayerprocess for producing high purity alumina(also used in the production of aluminum). In this process, aluminum oxide is dissolved from the mineral bauxite so that iron compounds and other impurities can be removed Then, aluminum hydroxide(AloH)) is precipitated from solution and reduced to Alo by heating Further preparation of the powders includes classification by size and micing be. fore shaping. Very fine powders required for new ceramics applications and so the are grains must be separated and classified according to size. Thorough mixing of the particles especially when different ceramic powders are combined, is required to avoid segregation. vanous additives often combined with the starting powders, usually in small are amounts. The additives include(1) plasticizer to improve plasticity and workability: (2) binders bond the ceramic particles into a solid mass in the final product, (3) wetting to agents for better mixing(4) denocculants, which help to prevent clumping and premature bonding of the powders and(5) lubricant, to reduce friction between ceramic grains during forming and to reduce sticking during mold release