Study on Preparation of High-Quality Magnesium Hydroxide and Calcium Hydroxide Products from Dolomite

Dolomite is an important calcium and magnesium resource with a wide range of applications. Pure magnesium hydroxide (MH) and calcium hydroxide (CH) are prepared from dolomite through calcination, steam hydration and precipitation drying. The effects of different calcination temperatures, holding times and steam hydration times on the decomposition products of dolomite are investigated. Pure MH and CH are obtained when the calcination temperature is 950°C, the holding time is 2 h, and the steam hydration time reaches 3 h. The characteristic diffraction peaks of CH and MH are confirmed by XRD and FTIR. SEM further reveals that CaMg(CO₃)₂, which yields lamellar MH and cubic CH, can be prepared using the described preparation method. In the analysis of the hydration products, the 950-2-3 product exhibits a mass loss of 1.17 g and has high purity. The proposed method offers many advantages, such as novelty, low environmental pollution and low cost, demonstrating considerable potential for the high utilisation of dolomite.