When the PH cost of the ammonia water is small, the supersaturation of the reaction is small, so the obtained magnesium hydroxide has a large particle length and a quick sedimentation speed; whilst the PH price of the ammonia water is tremendously large, the response supersaturation is enormously large, and the sedimentation time of the magnesium hydroxide lengthy. On the corresponding temperature, the supersaturation ratio has the greatest influence on the nucleation rate. consequently, it is vital to hold a tremendously large answer PH price (PH=1315) at some stage in the test, that is, a rather big oh-ion awareness. the effect of reaction temperature at the sedimentation performance of magnesium hydroxide when the reaction temperature is simply too low, the magnesium hydroxide produced by means of the reaction is in a colloidal state, and the filtration performance may be very bad. With the upward push of the response temperature, the response exceeds 10%. If it is cooled to room temperature under a sealed condition, its hydration charge can be lower than three%, which could reach the standard of silicon metallic grade magnesium oxide hydration rate.