煤泥浮选中Ca^(2+)吸附对高岭土和石英抑制作用的研究

Study on Ca^(2+)adsorption inhibition of kaolin and quartz in coal slime flotation

为探清Ca^(2+)对煤泥中其他杂质矿物的抑制作用,改善浮选效果,采用CaCl_(2)为抑制剂,柴油为捕收剂,松醇油起泡剂,探索实验得到柴油和松醇油最佳用量分别为1000 g/t和300 g/t。利用煤泥浮选和人工混合矿浮选考察了Ca^(2+)对煤泥中高岭土和石英的抑制效果,浮选实验均采用单元浮选实验流程,人工混合矿为4 g纯煤与1 g高岭土或1 g石英的混合矿。浮选实验开始前矿浆中分别加入0 mmol/L,2 mmol/L,4 mmol/L,6 mmol/L,8 mmol/L,10 mmol/L的CaCl_(2)溶液。结果显示:煤泥浮选中Ca^(2+)浓度由0 mmol/L增加到4 mmol/L时,可燃体回收率增加了8.24%,抑制效果明显,Ca^(2+)浓度大于4 mmol/L时,精煤灰分含量显著提高,不利于浮选;纯煤与高岭土混合矿浮选时,随着Ca^(2+)浓度增加,可燃体回收率一直保持稳定上升趋势,回收率从87.16%增加至96.18%;纯煤与石英混合矿浮选时,Ca^(2+)浓度增加到4 mmol/L后,可燃体回收率在91%上下波动且精煤灰分含量开始明显增加;通过粒度分析、Zeta电位测试研究Ca^(2+)吸附对高岭土和石英抑制机理,发现Ca^(2+)浓度由0 mmol/L增加到10 mmol/L时,高岭土粒径和石英粒径分别增加了0.71μm和0.84μm,高岭土和石英Zeta电位绝对值分别降低了10.57 mV和7.98 mV,矿物颗粒之间静电斥力减弱,更易聚集;浓度适中的Ca^(2+)对高岭土和石英抑制效果较好,浓度过低的Ca^(2+)对高岭土和石英抑制效果不明显,浓度过高的Ca^(2+)会导致煤泥浮选选择性降低,精煤灰分含量升高,浮选效果变差。

In order to investigate the inhibitory effect of Ca^(2+)on other impurity minerals in coal slime and improve the flotation effect,CaCl_(2) was used as an inhibitor,while diesel oil and pine oil were employed as collectors and frothers,respectively.Optimal dosages of diesel oil and pine oil are determined to be 1000 g/t and 300 g/t,respectively.Flotation experiments were conducted on both coal slime and artificially mixed ores to evaluate the inhibitory effect of Ca^(2+)on kaolin and quartz in the coal slime.The flotation process followed a single-cell flotation test procedure,and the artificially mixed ore contained 4 g of pure coal mixed with 1 g of kaolin or 1 g of quartz.Prior to commencing the flotation experiment,CaCl_(2) solutions with concentrations of 0 mmol/L,2 mmol/L,4 mmol/L,6 mmol/L,8 mmol/L,10 mmol/L were added to the slurry.The results show that when the Ca^(2+)concentration in coal slime flotation increases from 0 mmol/L to 4 mmol/L,the recovery rate of combustibles increases by 8.24%,signifying a significant inhibitory effect.However,an increase in the Ca^(2+)concentration above 4 mmol/L results in an obvious increase in the ash content,which is not conducive to flotation;when flotation is carried out on the mixed ore of pure coal and kaolin,the recovery rate of combustibles increases steadily as the Ca^(2+)concentration increases,the recovery rate increases from 87.16% to 96.18%;in terms of the flotation of mixed ore containing pure coal and quartz,the recovery rate of combustibles fluctuates around 91%after the Ca^(2+)concentration increases to 4 mmol/L,and the ash content begins to increase significantly;the inhibitory mechanism was analyzed via particle size analysis and Zeta potential testing,the results show that when the Ca^(2+)concentration rises from 0 mmol/L to 10 mmol/L,the particle size of kaolin and quartz increases by 0.71μm and 0.84μm,respectively,and the absolute value of the Zeta potential of kaolin and quartz decreases by 10.57 mV and 7.98 mV,respectively.The electrostatic repulsion between mineral particles weakens,making them more likely to aggregate;the moderate concentration of Ca^(2+)has a better effect on the inhibition of kaolin and quartz,the low concentration of Ca^(2+)has no remarkable effect,while high concentration of Ca^(2+)will reduce flotation selectivity,increase the ash content of clean coal,and deteriorate the flotation effect.