| 摘要 |
1. A method of obtaining a solution of calcium ions from lime, comprising: (i) treating the lime with an aqueous solution of a polyhydroxy compound of the formula HOCH2(CHOH)nCH2OH in which n is 1 to 6; and (ii) optionally separating insoluble impurities from the solution resulting from (i). 2. A method according to claim 1, wherein the lime is carbide lime. 3. A method according to claim 2 wherein insoluble impurities are separated from the solution resulting from (i). 4. A method according to claim 1, wherein the lime is a product of the calcining of limestone or dolomine. 5. A method as claimed in any one of claims 1 to 4, wherein the polyhydroxy compound is glycerol. 6. A method according to any one of claims 1 to 4, wherein the polyhydroxy compound is sorbitol, mannitol, xylitol, threitol or erythritol. 7. A method according to claim 6 wherein the polyhydroxy compound is sorbitol. 8. A method as claimed in any one of claims 1 to 7, wherein the polyhydroxy compound is employed as 10%-80% by weight solution in water. 9 A method as claimed in claim 6 or 7, wherein the polyhydroxy compound is employed as a 10% to 60% by weight solution. 10. A method as claimed in claim 5, wherein the glycerol is employed as a 60% to 80% by weight solution in water. 11. A method as claimed in claim 8, wherein the amount of lime is such as to provide 3-12 parts by weight per 100 parts by weight of the aqueous solution of the polyhydroxy compound. 12. A method as claimed in any one of claims 1 to 11 effected at a temperature of 5 degree C-60 degree C. 13. A method of producing a calcium containing product comprising the steps of: (a) preparing a solution of calcium ions according to the procedure of any one of claims 1 to 12; and (b) adding to the solution from (a) a precipitating agent which causes precipitation of the desired calcium containing product. 14. A method as claimed in claim 13, wherein the precipitating agent is carbon dioxide and the product obtained is precipitated calcium carbonate. 15. A method of producing precipitated calcium carbonate from carbide lime comprising: (a) treating the carbide lime with an aqueous solution of sorbitol to extract calcium from the carbide lime; (b) separating the insoluble impurities from the solution resulting from (a); and (c) treating the solution resulting from (b) with carbon dioxide. |
