| 摘要 |
1285252 A modified light hydromagnesite SOLVAY & CIE 27 Aug 1970 [28 Aug 1969] 41306/70 Heading C1A [Also in Division C3] A modified light hydromagnesite comprises spherical aggregates of small crystals having (a) a pore volume of 4000 to 6000 mm.<SP>3</SP>/gm., (b) a specific gravity of 0À2 to 0À4 kg./dm.<SP>3</SP>, (c) a mean particle diameter between 80 and 170 microns and (d) a mobility less than 5 mm. It is prepared by precipitation from an aqueous solution containing a soluble salt of magnesium (e.g. the sulphate) and an alkali metal carbonate or bicarbonate (up to 20% of which may be replaced by the corresponding hydroxide) by a double decomposition reaction in the presence of a crystallization habit modifying agent which is an alkali metal polyphosphate (e.g. sodium hexametaphosphate). |
