According to the difference of alkali thickness and oil temperature, the process of dealkalizing is divided into two types, one is low temperature with thick alkali (its initial temperature is 20 ~ 30 ℃, alkali thickness is 20 ~ 30 Be) and another one is high temperature with light alkali (its initial temperature is 75 ℃, alkali thickness is 10 to 16 Be). The former is generally applied and the latter is mainly used for crude oil which has low acid value, light clour and lustre, and less impurity.The main equipment of Small Scale Castor Oil Mill is sheller, it crushes the peanut shell under the effect of twisting and tearing of insection that on a pair of millstone. This machine adopts high strength alloy steel tooth plate, which has advantages of long using life, good abrasion resistance, convenient maintenance, cheap spare parts, etc. The requests of shelling are: shell in castor seed rate is not over 1%, the kernel in shell rate is not over 0.5%.