电解质对低阶煤油泡浮选矿化过程的影响

Effects of electrolytes on the mineralization process in oily-bubble flotation of low rank coal

浮选矿浆中离子的种类与浓度直接影响着矿物颗粒和气泡的表面电位,进而支配着浮选矿化过程。从热力学和动力学两个方面入手,通过DLVO理论探究了不同电解质对煤粒和油泡间的相互作用势能的影响,结合其在不同电解质条件下诱导时间的差异,最终通过相应条件下的油泡浮选试验来证实电解质对低阶煤-油泡浮选矿化黏附过程的影响。结果表明:对于NaCl和CaCl_2两种电解质,随其浓度的增大,煤粒和油泡表面电位的负值均不断减小,煤粒和油泡间的能垒也不断降低,当CaCl_2浓度为100 mmol/L时,煤粒和油泡间的相互作用不存在能垒;并且随这两种电解质浓度的增大,黏附过程的诱导时间逐渐减小,相应地可燃体回收率不断提高,且相同的电解质浓度下,CaCl_2电解质对其相互作用能垒和诱导时间的降低程度更大,可燃体回收率更高。而对于AlCl_3电解质,当其浓度大于20 mmol/L时且随浓度的增大,煤粒和油泡间的相互作用能垒和诱导时间不断增大,相应地可燃体回收率则不断降低。

The type and concentration of ions in the flotation pulp directly affect the surface potential of mineral particles and bubbles hence control the mineralization process in flotation.Starting from both aspects of thermodynamics and kinetics,the influence of different electrolytes on the interaction energy between coal particles and oil bubbles was calculated by DLVO theory.Additionally,the induction time between coal particles and oily bubbles was used to evaluate the mineralization efficiency at different electrolyte conditions,while oily-bubble flotation tests were conducted to verify the effects of electrolytes on the attachment and mineralization processes between coal particles and oily bubbles. The results indicated that negative values of surface potential of coal particles and oil bubbles both decreased with the increase of concentration of Na Cl and CaCl2,and the interaction energy barrier between coal particles and oil bubbles decreased as well.No interaction energy barrier was observed when the concentration of CaCl2 was 100 mmol/L. With the increase of concentration of the two electrolytes,it showed a gradual decline in the induction time of attachment of coal particles to oily bubbles and the combustible recovery was improved correspondingly.At the same electrolyte con-centration,the interaction energy barrier and induction time between coal particles and oil bubbles in CaCl2 solution were lower than that of in NaCl solution,while the combustible recovery was higher correspondingly.However,when the concentration of AlCl3 electrolyte exceeded 20 mmol/L,the interaction energy barrier and induction time increased gradually while the combustible recovery decreased with the increase of concentration of AlCl3 electrolyte.