细粒石英的相对润湿性及其浮选行为研究

Study on Relative Wettability and Flotation Behavior of Fine Quartz Particles

目前测定粉体接触角的方法主要有压片法和渗透法,但由于难以制得表面光滑的样品,因此压片法应用有很大的局限性。根据Washburn原理,通过测定液体在粉体柱内产生的压差随时间的变化计算不同药剂条件下石英的相对接触角。并结合单矿物浮选试验结果来判断相对接触角是否可以准确表征矿物表面润湿性。结果表明:不同药剂条件下石英回收率与测得的接触角呈正相关,相对接触角越大,回收率越高;在pH值为12、Ca^(2+)浓度为3.75 mmol/L、油酸钠用量为2.81 mmol/L条件下,浮选效果最好。在此基础上,使用JK99C型全自动表面张力仪测定了不同条件下溶液的表面张力,计算了气泡与颗粒黏着单位面积前后自由能的变化,从热力学角度分析了与药剂作用后石英表面润湿性变化及其浮选行为发生变化的原因。

The main methods to measure the contact angle of powders are pressing plate method and capillary penetration method. A commercial contact angle measuring instrument（ JF99 A） was applied according to Washburn technique to determine the relative contact angle of quartz under different reagent conditions by measuring the changes of the pressure difference over time produced by the liquid in the powder column. Combined with the flotation tests of quartz particles at the same concentrations,the relationship between their recovery and relative contact angle was analyzed,which proved that the relative wetting contact angle can characterize the surface wettability of quartz powders accurately. The flotation recovery was highest under the conditions of p H 12. 0,Ca^2＋ concentration of 3. 75 mmol/L and sodium oleate concentration of 2. 81 mmol/L. Moreover,the surface tensions at different conditions were measured by a full-automatic tensiometer（ JK99 A）. Under each condition,the free energy changes（ ΔG） per unit area before and after the adhesion of bubble and particle were calculated respectively,which could illustrate the influences of reagents on flotation from the perspective of thermodynamics.