| 摘要 |
In a method of treating clay-containing phosphate rock comprising at least mining the phosphate rock, reducing the phosphate rock to a predetermined size range, adding water to the phosphate rock, and storing the admixture containing at least the phosphate rock and water; the improvement characterized by adding to the admixture an amount effective to control problems associated with the swelling of residual clays of a chemical treatment selected from the class consisting of aliphatic hydroxy acids containing 2-6 carbon atoms, inclusive, of which citric acid and tartaric acid are members; the aliphatic hydroxy acid salts, and effective blends of the aliphatic hydroxy acid or the aliphatic hydroxy acid salts with a strong caustic, or base. The chemical treatment prevents a build up of viscosity such that the admixture remains pumpable even with a concentration of solids in excess of 66 percent by weight. Moreover, in phosphoric acid production, the equality of the calcium sulfate crystals is improved such that they are more readily removable by filtering. An effective amount of chemical treatment, preferably, is, for example, one pound per ton of phosphate rock and no more than about six pounds per ton (0.05-0.3 percent by weight). |
