The flotation process is a particle-hydrophobic surface-based separation technique. To improve the essential flotation steps of collision and attachment probabilities, and reduce the step of detachment probabilities b...The flotation process is a particle-hydrophobic surface-based separation technique. To improve the essential flotation steps of collision and attachment probabilities, and reduce the step of detachment probabilities between air bubbles and hydrophobic particles, a selectively designed cavitation venturi tube combined with a static mixer can be used to generate very high numbers of pico and nano bubbles in a flotation column. Fully embraced by those high numbers of tiny bubbles, hydrophobic particles readily attract the tiny bubbles to their surfaces. The results of column flotation of Pittsburgh No. 8 seam coal are obtained in a 5.08 cm ID and 162 cm height flotation column equipped with a static mixer and cavitation venturi tube, using kerosene as collector and MIBC as frother. Design of the experimental procedure is combined with a statistical two-stepwise analysis to determine the optimal operating conditions for maximum recovery at a specified grade. The effect of independent variables on the responses has been explained. Combustible material recovery of 85–90% at clean coal product of 10–11% ash is obtained from feed of 29.6% ash, with a much-reduced amount of frother and collector than that used in conventional column flotation. The column flotation process utilizing pico and nano bubbles can also be extended to the lower limit and upper limit of particle size ranges, minus 75 lm and 300–600 lm, respectively, for better recovery.展开更多
The fundamental aspects of The Timed-Release Analysis (TRA) and some problems are analysed. Having studied the attribute of optimum flotation test results and the way of optimum test conditions, the auther put forward...The fundamental aspects of The Timed-Release Analysis (TRA) and some problems are analysed. Having studied the attribute of optimum flotation test results and the way of optimum test conditions, the auther put forward a proposal to improve this test method by adding a new test step of scavenging flotation and using optimum test conditions varied with different fine coals instead of the given ones settled by the TRA norm. Comparison between test results of the two methods of TRA shows that the improved method is very good.展开更多
颗粒-气泡间相互作用行为的研究对理解浮选原理至关重要。在颗粒-气泡间力学理论的基础上采用离散元法(Discrete Element Method,DEM)构建了颗粒-气泡间相互作用行为的模拟系统,模拟了粒度为0.1 mm,密度级分别为-1.3、1.3~1.4、1.4~1.5...颗粒-气泡间相互作用行为的研究对理解浮选原理至关重要。在颗粒-气泡间力学理论的基础上采用离散元法(Discrete Element Method,DEM)构建了颗粒-气泡间相互作用行为的模拟系统,模拟了粒度为0.1 mm,密度级分别为-1.3、1.3~1.4、1.4~1.5、1.5~1.6、1.6~1.7、+1.7 g/cm^(3)的球形煤颗粒与固定气泡在静止水环境中的相互作用行为。研究了颗粒-气泡间相互作用行为的各阶段以及各阶段颗粒速度变化规律、颗粒密度与颗粒-气泡间临界碰撞角的关系、颗粒密度与颗粒捕获概率的关系。模拟结果表明,颗粒-气泡间相互作用行为可分为5个阶段:自由沉降阶段、绕流运动阶段、颗粒在液膜上滑动阶段、液膜破裂并形成三相接触线(TPC)阶段、伴随TPC滑动阶段。颗粒以自由沉降末速接近气泡,在临近气泡表面时会做绕流运动,运动轨迹发生改变。当颗粒与气泡发生碰撞时,其速度降至最小值。碰撞后颗粒随即在气泡表面滑动,滑动速度先逐渐增加,然后急剧下降,再继续增加,在气泡“赤道”位置附近时其速度达到最大值,越过“赤道”后速度开始逐渐降低,最终停留在气泡底部。颗粒在气泡表面的滑动速度近似关于气泡“赤道”对称。当颗粒的密度级从-1.3 g/cm^(3)增加至+1.7 g/cm^(3)时,颗粒-气泡间临界碰撞角从50.77°降低至31.93°,气泡对颗粒的捕获概率从51.74%降低至22.04%。展开更多
基金provided by West Virginia State Coal and Energy Research Bureau (CERB)the Department of Mining Engineering,West Virginia University
文摘The flotation process is a particle-hydrophobic surface-based separation technique. To improve the essential flotation steps of collision and attachment probabilities, and reduce the step of detachment probabilities between air bubbles and hydrophobic particles, a selectively designed cavitation venturi tube combined with a static mixer can be used to generate very high numbers of pico and nano bubbles in a flotation column. Fully embraced by those high numbers of tiny bubbles, hydrophobic particles readily attract the tiny bubbles to their surfaces. The results of column flotation of Pittsburgh No. 8 seam coal are obtained in a 5.08 cm ID and 162 cm height flotation column equipped with a static mixer and cavitation venturi tube, using kerosene as collector and MIBC as frother. Design of the experimental procedure is combined with a statistical two-stepwise analysis to determine the optimal operating conditions for maximum recovery at a specified grade. The effect of independent variables on the responses has been explained. Combustible material recovery of 85–90% at clean coal product of 10–11% ash is obtained from feed of 29.6% ash, with a much-reduced amount of frother and collector than that used in conventional column flotation. The column flotation process utilizing pico and nano bubbles can also be extended to the lower limit and upper limit of particle size ranges, minus 75 lm and 300–600 lm, respectively, for better recovery.
文摘The fundamental aspects of The Timed-Release Analysis (TRA) and some problems are analysed. Having studied the attribute of optimum flotation test results and the way of optimum test conditions, the auther put forward a proposal to improve this test method by adding a new test step of scavenging flotation and using optimum test conditions varied with different fine coals instead of the given ones settled by the TRA norm. Comparison between test results of the two methods of TRA shows that the improved method is very good.
文摘为克服传统测量浮选回收率方式存在的低效率、滞后性等问题,结合紫金山硫化铜矿浮选厂生产情况,采用基于MI(Mutual Information)互信息法对选厂原矿品位、丁铵黑药用量等浮选条件因子进行特征选择,在此基础上,建立了基于BP(Back Propagation)、GWO-BP(Grey Wolf Optimizer-Back Propagation)、I-GWO-BP(Improved-Grey Wolf Optimizer-Back Propagation)的三种浮选回收率预测模型,并选取紫金山硫化铜矿浮选车间生产数据进行神经网络训练与验证试验,分析了浮选回收率预测模型的准确性。结果表明:相较于基于BP、GWO-BP的浮选回收率预测模型而言,基于I-GWO-BP的浮选回收率预测模型具有更大的相关系数和更小的均方误差根,说明该模型泛化拟合能力更强,对浮选回收率的预测值在很大程度上逼近于真实值,预测精度更高。本研究结果可为实现浮选回收率高效、准确、自动的在线预测技术开发提供支持。
