Co-production and modification of magnesium hydroxide and calcium carbonate by controlled carbonization of dolomite
The comprehensive use of dolomite for the development of high-end products and their technologies have become the focus of current researchers.In this paper,high value-added magnesium hydroxide and calcium carbonate were prepared by controlled carbonation method of dolomite and modified.The effects of pH at the end-point,temperature and CO2 flow rate of carbonation on the crystalline and particle morphology of the products,as well as the effects of zinc stearate addition,stirring speed,time and temperature on the modification of the products were investigated respectively.The results showed that when the pH at the end-point of carbonation reaction was controlled to 10.5,the products contained only calcium carbonate and magnesium hydroxide;the optimal carbonation reaction conditions were 20℃ and CO2 flow rate 1L/min,and the average particle size of magnesium hydroxide and calcium carbonate was 190.4nm;the optimal modification conditions of magnesium hydroxide and calcium carbonate were zinc stearate addition 1.0％,stirring speed 600r/min,modification time 60min,and modification temperature 50℃,the activation degree of the modified magnesium hydroxide and calcium carbonate was 95.8％,and the oil absorption value was 41.2g/100g.
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