Study On The Mechanism And The Process Of The Separation Between Andalusite And Quartz By Direct Flotation

With the development of the iron and steel industry, the requirement of refractory materials is continually increasing. Andalusite, as a superior raw material of refractory materials, has been drawing more and more attention. Since there are a large number of gangues, such as aluminosilicate and quartz, in the raw ore of China's andalusite, the grade is low and it can be utilized only after beneficiation.In order to achieve the separation of andalusite and quartz, the flotation experiments of pure minerals and actual ore were carried out, and the reagents mechanism were studied by means of zeta potential measurement, infrared spectroscopy, and so on.The results of single mineral flotation tests showed that the flotation separation of andalusite and quartz was achieved by adopting CSB as collector. When there existed Fe3+ in the pulp, quartz was activated obviously, which caused the flotation behavior of the two minerals identical, and should add depressants to achieve the separation. CSY exhibited good selectivity, it depressed quartz activated by Fe3+ effectively, whereas hardly influenced the floatability of andalusite.The experimental results of actual ore tests proved that the andalusite concentrate with a grade of 53.46% A12O3 and the quartz concentrate with 92.74% SiO2 was obtained by adopting the flowsheet of "iron removal by high-intensity magnetic separation-slimes and titanium removal by shaking table-the beneficiation of mica by reverse flotation-the separation of andalusite by direct flotation", using sulfate as pH regulator, CSY as depressant, and CSB as collector.The results of zeta potential measurement indicated that the point of zero charge of andalusite and quartz was approximately 4.5 and 2.0 respectively. The zeta potential of andalusite at pH 3.0～3.1 was positive and quartz was negative, so they can be separated by direct flotation using CSB, an anionic collector. The zeta potential of both andalusite and quartz turned positive by Fe3+, while it had only a little decrease by Al3+, Ca2+ and Mg2+. The zeta potential of quartz activated by Fe3+ changed to negative direction through the addition of CSY.The desorption experiments indicated that the adsorption of the collector CSB on andalusite was not only physical adsorption, but also chemical adsorption. While it was presented only by physical adsorption on the surface of quartz.The results of infrared spectroscopy showed that CSB adsorbed on andalusite by physical and chemical adsorption, and chemical adsorption was dominant, which generated new characteristic peak on the surface of andalusite. The adsorption manner of CSY on the surface of quartz activated by Fe3+ was physical adsorption, it could act with Fe3- and its hydrolysate by electrostatic force, thus eliminating the activation and achieving the depression.