PREPARATION OF CaCO3 FROM CALCIUM OXALATE.

The authors report the results of a study of preparation of CaCO//3 from Ca(NO//3)//2 solutions, with formation of calcium oxalate as an intermediate product. In this investigation Ca(NO//3)//2 solution of 2 M concentration was treated with milk of lime in order to remove extraneous metallic (iron, magnesium, etc. ) impurities. The filtrate was added, with continuous stirring, to ammonium oxalate solution (0. 05 M) heated to 40 degree , prepared from the 'pure' grade reagent. All the starting materials were taken in amounts calculated to give 1 kg of CaCO//3. After separation from the mother liquor the precipitated calcium oxalate was washed to remove water-soluble impurities. Chemical analysis showed that the calcium carbonate corresponded to the analytical-grade reagent.