FREMGANGSMAATE TIL FREMSTILLING AV EN OVERVEIENDE MAGNESIUMKARBONATHOLDIG, SMAAPLATEFORMET KALSIUM-MAGNESIUM-KARBONAT-BLANDING MED BASISK KARAKTER

1533323 Calcium and/or magnesium carbonate VEREINIGTE ALUMINIUM-WERKE AG 19 Jan 1976 [21 Jan 1975 (2) 31 Jan 1975 8 Jan 1976] 02053/76 Heading C1A [Also in Division D2] Dolomite is calcined at 1000-1100‹ C. and the resultant oxide mixture of calcium and magnesium is suspended in at least 20 parts by weight of water per 1 part oxide, and carbon dioxide gas is introduced into the suspension to convert the hydroxides back to carbonates. A basic calciummagnesium carbonate may be produced by calcining dolomite, slaking the product, suspending in 20-60 parts of water per I part of oxides and concentrating the suspension after CO 2 treatment. A basic magnesium carbonate is made by using 60 parts of water per 1 part of oxides in suspension, and removing undissolved calcium carbonate by filtration and heating the solution to 70-80‹ C. at at least 10‹ C. min-1 until the Mg carbonate has precipitated. The product characteristically has lamellar particles with the fineness of particles being < 1Ám, and a whiteness exceeding 95%, with a high shape factor of at least 1:80.