【作者】 胡卫新；

【导师】 刘炯天；

【作者基本信息】 中国矿业大学 ， 化学工艺， 2010， 博士

【摘要】 贫杂难选矿石中细颗粒及微细颗粒难以矿化问题是柱分选研究的难题之一。浮选过程中气体含量的多少和气体质量直接决定了疏水性矿物产率的高低和气泡的荷载能力。气含率是对浮选过程中气体含量大小和气体质量的表述。目前,浮选柱浮选过程中,依据充气量来调控气体含量技术比较成熟,但气泡的质量往往无法得到保证,影响了浮选的回收率和选择性。因此,本文开展基于气泡的浮选柱气含率影响机制与调控研究,为在高紊流、高充气量分选环境中如何控制气泡尺寸提供理论基础,为浮选柱满足工业过程控制需要提供技术支撑,实现浮选柱对微细颗粒的高效分选。首先,本文开展了浮选柱分选煤泥、硫化铜、赤铁矿和铝土矿的适宜气含率试验研究。试验采用压差法测定气含率,分析了不同气含率情况下浮选柱分选煤泥、硫化铜、赤铁矿和铝土矿的效果。结果表明:气含率对分选指标的影响有一定共性,气含率的增加会导致目的矿物回收率的提高,精矿品位逐渐降低;不同的矿物达到最佳分选效果时,所对应的气含率大小并不相同。由此说明,气含率对矿化效率有一定影响,从而影响浮选精矿品位和回收率,通过气含率调控可优化浮选过程和提高浮选效率。浮选过程中,气泡尺寸直接影响气含率的大小,而影响气泡尺寸和气含率大小的参数很多,其中循环压力、充气量和起泡剂用量是最关键的因素。为深入研究这三种因素对气含率的影响关系,本文开展了试验研究和流场数值模拟研究。试验研究部分借助MATLAB软件作为气泡图像分析手段,分别研究了循环压力、充气量和起泡剂用量对气泡尺寸和气含率大小的影响,探索了各因素的影响规律。数值模拟研究部分利用流体力学软件FLUENT对浮选柱内气液两相流场进行了数值模拟研究,从理论上探讨各种因素对气含率的影响规律,并分析了气速随循环压力、充气量的变化规律,结果表明:两相流场模拟结果与试验结论基本一致;气含率在柱体内的径向分布为中心处较高、四周较低,轴向分布为中间高、两边低。通过影响因素试验研究和流场数值模拟研究,为气含率的影响机制和调控研究打下了良好的基础。在前面研究的基础上,又从理论上探讨了气含率的影响机制和调控,从控制的角度确定气含率调控策略。首先依据质量守恒定律,对浮选柱内气-液-固三相流动进行恒算,从而得到浮选柱气含率的计算公式。在此基础上,对矿化气泡的运动进行了深入分析,以矿化气泡受力平衡为出发点,重点讨论了气泡大小与循环压力、循环流量、液相表面张力等因素的关系,结合气相体积流量、处理量以及浮选回收率等因素的分析,得到基于工况参数的气含率关系模型数学表达式。再将该数学表达式进行单因素化,通过清水试验和矿物分选试验对单因素化的公式进行验证,发现通过公式计算的结果与试验结果基本一致。然后,基于气含率的分析计算,对气含率的调控策略进行了探讨。通过分析浮选动力学,确定气含率调控的基本思想为:以浮选作业指标为最终目标,通过综合调控起泡剂用量、循环压力和充气量等因素,提出了以专家控制系统为核心、以入料性质为前馈、以参数检测量为反馈的气含率调控策略。最后,本研究结合大红山铜矿开展了分选试验,进行强化流程控制与气含率调节的实践。结果表明:在原矿品位为0.72%的情况下,采用浮选柱一粗一精工艺,得到精矿品位25.25%,回收率93.39%的指标,而且回收率比浮选机分选高出0.97个百分点。分选试验成功实现了浮选柱气含率的可控、可调,这对矿物分选的过程控制具有重要的指导作用,大大推进了柱式短流程分选过程控制技术的发展。该论文有图69幅,表35个,参考文献148篇。更多还原

【Abstract】 Fine and micro-fine particles in poor, mixed, difficult mineral are difficult to mineralize, which is one of the most difficult problems in column separation research. The ammount of gas hold-up and the quality of gas decide the hydrophobic mineral yield and load ability directly. Gas hold-up characterizes the ammount and quality of gas in flotation process. At present, the techology of regulating the ammount of gas based on inflating volume has been quite mature in column flotation process. However, the quality of bubbles can’t always be ensured which has effect the recovery and selectivity of flotation. With the aims mentioned above, the study on the formation mechanism and regulation of flotation column gas hold-up has been made in this dissertation, which will provide theory fundamental for controlling the size of bubbles in the environment of strong turbulent with a great amount of inflating volume, and provide technology support for flotation column industrial concrol to achieve effective separation of micro-fine particles.First of all, the research on suitable gas hold-up of coal slime, copper sulfide, hematite and bauxite column flotation separation has been made. Using pressure-difference method to measure gas hold-up, under the condition of differernt gas hold-up, the column separation effect of coal slime, copper sulfide, hematite and bauxite have been analysized. The results show that the influence of gas hold-up on separation index has some kind of commonness. Increasing gas hold-up leads to increasing recovery of purpose mineral while the concentrate grade reduces gradually. While achieving the best separation effect, the corresponding gas hold-up of different mineral ores is different. Therefore, gas hold-up affects mineralization to some extent, which affects concentrate grade and recovery. By regulating gas hold-up the flotation process can be optimized to improve flotation effect.In flotation process, the size of bubbles affects gas hold-up directly. Circulating pressure, inflating volume and frother dosage are the key factors while there are many factors affect the size of bubbles and gas hold-up. To research the influence of these three factors on gas hold-up, experimental and flow field numerical simulation study has been made. During experimental study process, using software MATLAB as bubble image analysis tool to research the influence of circulating pressure, inflating volume and frother dosage on the size of bubbles and gas hold-up separately and get the effect regularity. During numerical simulation study process, using fluid dynamics software FLUENT to make numerical simulation research of gas-fluid two-phase flow field in flotation column. Effect regularity of each factor has been investigated theoretically, also the gas velocity variation regularity while changing circulating pressure and inflating volume has been analysized. The results show that two-phase flow field simulation results are consisitent with experimental results. The radial distribution of gas hold-up in column is higer in the middle and lower at around. The axial distribution is higher in the middle and lower on both sides. Factors experimental and flow field numerical simulation research has provided great basic for the study on the formation mechanism and regulation of gas hold-up.Basing on the research mentioned above, the formation mechanism and regulation of gas hold-up has been discussed. From the perspective of controlling the regulation strategy of gas hold-up has been made. Basing on conservation of mass to make balance caculation of gas-liquid-solid three-phase flow, the flotation column gas hold-up caculation formula has been achieved. On this basis, making force balance of mineralization bubble as a starting point, the relationship between the bubble size and the factors of circulating pressure, circulating flow, liquid-phase surface tension has been emphatically discussed. Combined with the factors analysis such as gas-phase volume flow, processing capacity and flotation recovery, the gas hold-up relationship model mathematical expression basing on working parameters has been got. Then make this mathematical expression single-factor change. Through fair-faced water experiment and mineral separation experiment the expression has been verified and it has been found out that the results caculated using expression are the same with experiment results. Then the regulation strategies has been discussed basing on gas hold-up analysis caculation. By analyzing flotation dynamics, the basic idea of gas hold-up regulation can be confirmed as follow: making flotation index as the final goal, through comprehensive regulation of the factors of frother dosage, circulating pressure and inflating volume, the gas hold-up regulation strategy with core of expert regulation system, feedforward of feed properties, feedback of parameter test quantity has been proposed.Finally, the separation experiments combined with Dahongshan copper ore have been carried out to strengthen flow-chart control and gas hold-up regulation. The results show that the index of concentrate grade 25.25%, recovery 93.39% has been achieved using flotation column one-coarse-one-regrade flow-chart in the situation of raw ore grade 0.72%, and the recovery is 0.97 percent point which is higer than that of flotation machine. separation experments have achieved flotation column gas hold-up contrallable and adjustable successfully, which is an important orientation for mineral separation process regulation and will promote the development of column short-flow separation regulation techonolgy greatly.更多还原