Salt is almost always treated with additives (magnesium carbonate, magnesium oxide, calcium silicate) to prevent it from absorbing moisture and ensure that it remains free flowing and granular.
Calcite or marble is crushed, graded, and surface treated to be all kinds of technical natural calciumcarbonate with different fineness. It is widely used in rubber, plastic, paint, and paper.
以方解石、大理石经超细粉碎、分级得到系列不同细度的重质碳酸钙，再经表面处理制得重质活性碳酸钙。
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Results: (1) The rats treated with calcium citrate and calcium acetate enhanced lead apparent absorptivity, as compared with calcium carbonate.