钙离子对铝土矿选择性絮凝的影响及消除的试验研究

采用沉降试验方法, 研究了钙离子对一水硬铝石、高岭石、伊利石和叶腊石单矿物分散性能的影响规律。结果表明, 碱性条件下, 钙离子对矿物的分散性影响较大, 一水硬铝石、高岭石和叶腊石的聚沉十分明显, 原来的分散体状态被破坏。虽然采用碳酸钠和三聚磷酸钠均可消除体系中的钙离子, 但单矿物和实际矿石试验结果均表明, 三聚磷酸钠是硬水体系下的良好调整剂, 在消除了钙离子影响的同时, 可得到与软水条件下相同的分离效果和指标。在碱性条件下, 一羟基钙络合物和氢氧化钙沉淀在矿物表面的吸附造成了矿物颗粒间的凝聚。碳酸钠主要与钙离子反应生成碳酸钙沉淀, 而三聚磷酸钠则与钙离子形成稳定的环状内络物(螯合物), 从而消除了钙离子的聚沉作用。

Experiments on the Influence and Elimination of Calcium Ions for Selective Flocculation of Diasporic Bauxite

The effect of calcium ions on the dispersion of diaspore, kaolinite, illite and pyrophllite was investigated using sedimentation test. The results show that calcium ions have significant influence on the dispersion of minerals in alkaline medium which make diaspore, kaolinite, and pyrophyllite coagulating obviously. Although the calcium ions can be eliminated by either sodium carbonate or sodium tripolyphosphate, the experiment results of single minerals and bauxite ores indicate that sodium tripolyphosphate has better efficiency, equivalent results as the soft water system could be achieved after the elimination of calcium ions by sodium tripolyphosphate. The adsorption of hydroxy complexation CaOH⁺ and Ca(OH)₂ on mineral surfaces causes the coagulation minerals in alkaline medium. Sodium carbonate reacts with calcium ion to form the CaCO₃, but sodium tripolyphosphate reacts with calcium ion in the form of chelating product and then eliminates the coagulation effect of calcium ions on aluminum-silicate minerals.