Method of carbonating lime and separating the same from magnesia

摘要

553,763. 'Calcium carbonate ; magnesia. CLARK, G. M. (New England Lime Co.). Nov. 11, 1940, No. 16363. [Class 1 (iii)] Suspensions of lime and magnesia such as are obtained from slaked, burnt dolomite are carbonated so as to separate calcium carbonate in dense form suitable for use as a pigment, and to leave a magnesia suspension from which either pure magnesia or a magnesia containing calcium and suitable for use in making magnesia bricks may be separated. The carbonation is effected continuously and a definite concentration of. calcium hydroxide maintained in the liquid by regulating the feed of the suspension and of the carbondioxide. The particles of calcium carbonate remain suspended in the liquid for a definite period of time. The carbonation vessel 10 is continuously supplied with suspensionthrough an inlet 13 and with carbon dioxidethrough a pipe 16 with a distributing baffle 20. Paddles 11 agitate the liquid which is continuously discharged through an outlet 26. The concentration of dissolved calcium hydroxide is measured by a meter 24 operated according to resistance, conductivity, pH value or otherwise- and may be connected to a control device to vary the feed of the suspension or the carbon dioxide. The concentration is maintained below that at which the liquid is saturated with calciumhydroxide.