The use of the atomization process to control the cooling rate during solidification process of previously refined silicon to produce chemical grade silicon particles is investigated. The cooling rate is very important to obtain a tailored microstructure, related with silicon behavior during the production of methylchlorosilanes, a silicone production raw material. The production of methylchlorosilanes is carried out in a fluidized bed reactor (the gas methylchloride is fed into a fluidized bed of fine silicon particles mixed with a catalyst, for example copper). The presence and distribution of specific intermetallics in silicon microstructure are essential to obtain a good silicon performance, reactivity and selectivity. Results of silicon particles produced in water and gas atomizers are presented and discussed. A methodology to determine intermetallics shape and location is presented. The effects of cooling rate on microstructure are investigated. Aspects like particle sizes, morphology and internal porosity are discussed.