ABSTRACT
Thermal pretreatment is necessary to heat an ore to a certain temperature to effect a change that results in improving a subsequent process such as crushing, reduction, or leaching. This treatment is the simplest process because no reagent is added to the ore. The change that takes place may be a phase transformation, dehydration or dehydroxylation, dissociation, or destruction of organic matter; in some cases, melting of the raw material is intended. Phase transportmations that occur when minerals are heated are usually accompanied by a change in volume. This change results in many cases in the cracking of surfaces or curmbling of solids, thus rendering them easy to crush and to leach. Use is made of this phenomenon in treating lithium ores. Heating of ores in air at a moderate temperature may have a beneficial effect for subsequent leaching process due to destruction of organic matter or oxidation of certain ferrous minerals.
