Extrusion is executed by mixing the powder with liquid, additives, or dispersants and then compressing the mixture and forcing it through a die.  The product is then dried and broken down to the desired particle size. Extruded powders are dense.  Extrusion is typically used for ingredients such as minerals and highly-hygroscopic products which benefit from reduced surface area, as well as products that are subject to oxidation.   Extrusion for agglomeration should not be confused with the more common food extrusion process that involves creating a dough that is cooked and expands as it passes through the die.