The invention discloses a
precipitated calcium carbonate production technology for reducing
magnesium and increasing
calcium. The technology comprises the steps as follows: 1) a desulfurizing
tower is serially connected with a washing
tower in
kiln gas purification, and a desulfurizer is added to a
liquid phase of the desulfurizing
tower, so that the purification effect of a
kiln gas is improved, and meanwhile, the dosage of circulating water is reduced; 2) a raw
slurry pre-
ageing process and a dynamic
ageing process are adopted, the "back-mixing" phenomenon is avoided, and the
ageing time of the raw
slurry is ensured; 3) a
carbonation reaction kettle adopts a stirring apparatus with three
layers of paddles, so that the
carbonation reaction time is shortened, and the
utilization rate of the
kiln gas is increased; 4)
magnesium is separated out from
mother liquor from which
calcium carbonate is separated out by adopting a
steam pyrolysis method, filtrate is returned to a digestive process, and cyclic utilization of water is achieved. The
precipitated calcium carbonate product obtained by the technology is small in grain size (D50 is approximate to 4mu), high in whiteness (greater than or equal to 94), low in
magnesium content (MgO is smaller than or equal to 0.5%), and low in
alkalinity (pH is smaller than or equal to 9), and is more applicable to the industries of plastic steel and the like with special demands on the magnesium content, the whiteness, the
alkalinity and the like besides of meeting the industries such as rubber, plastic,
papermaking and coatings.