低阶煤颗粒-气/油泡间的诱导时间研究

为表征低阶煤颗粒-气/油泡间矿化过程的差异,通过Sutherland理论下固体颗粒进入泡沫产品的总概率(E)和浮选速率常数(k)之间关系,并结合低阶煤颗粒-气/油泡的浮选速率试验,求得了低阶煤颗粒-气/油泡间的诱导时间。浮选实验研究表明,在相同的捕收剂消耗量下低阶煤-油泡浮选产率均高于低阶煤-气泡浮选产率。诱导时间测试表明,低阶煤颗粒-油泡间的诱导时间(35 ms)要明显低于低阶煤颗粒-气泡间的诱导时间(93 ms)。上述实验结果表明,油泡表面的疏水性要强于传统浮选气泡表面的疏水性。然而,进一步利用Sutherland理论中固体颗粒进入泡沫产品的总概率和浮选速率常数之间的数学关系,并结合低阶煤颗粒-气/油泡的浮选速率试验求得的低阶煤颗粒-气/油泡间的诱导时间分别为9.67和8.46 ms,其与诱导时间测试仪分别测量的诱导时间差异很大。这主要是由于在实际浮选过程中气/油泡的上升速度分别为23.26和22.68 cm/s,其远高于2015EZ型诱导时间仪测试过程中气/油泡碰撞速度(2.0 cm/s)。因此,诱导时间理论计算表明气泡-颗粒间的碰撞速度对颗粒-气泡间的诱导时间影响很大。上述研究结果表明油泡浮选效果优于传统浮选的内在原因在于低阶煤颗粒-油泡间的诱导时间小于低阶煤颗粒-气泡间的诱导时间。     

硫酸锌添加顺序对乙硫氮在方铅矿和闪锌矿表面吸附的影响

研究了无机抑制剂硫酸锌及其与乙硫氮不同添加顺序对方铅矿和闪锌矿浮选行为的影响。当先加入硫酸锌时,硫酸锌对闪锌矿有较强的抑制作用,对方铅矿有轻微的抑制作用;当硫酸锌后于乙硫氮加入时,对方铅矿的抑制作用减弱,而对闪锌矿的抑制作用增强。吸附量测定结果表明,乙硫氮强烈吸附在方铅矿表面,硫酸锌对乙硫氮在方铅矿表面吸附影响很小,而乙硫氮与闪锌矿表面作用较弱,吸附量较小。红外光谱研究表明,无论硫酸锌先加还是后加,均明显降低乙硫氮在闪锌矿表面的吸附,而硫酸锌对乙硫氮在方铅矿表面的吸附影响较小,特别是硫酸锌后加时对乙硫氮在方铅矿表面吸附强度的抑制作用减弱。飞行时间二次离子质谱研究表明,与硫酸锌先加时相比,硫酸锌后加时,方铅矿表面吸附的氢氧化锌亲水胶体更少、乙硫氮略多,而闪锌矿表面吸附的氢氧化锌亲水胶体更多、乙硫氮更少。因此,硫酸锌后于乙硫氮添加时更有利于铅锌分离。     

低阶煤颗粒-气/油泡间的疏水力常数研究

浮选实验表明油泡对低阶煤颗粒的捕收能力要远强于传统浮选过程的起泡。这主要是由于油泡表面被捕收剂覆盖,其表面疏水性要远高于气泡表面的疏水性。因此,在油泡浮选矿化过程中,低阶煤颗粒-油泡间水化膜的薄化速度要远快于煤颗粒-气泡间的薄化速度。诱导时间测试发现,随着DAH溶液浓度从10~(-7) mol/L增加到5×10~(-5) mol/L时,低阶煤颗粒-气泡间的诱导时间从93 ms下降到12 ms。随着DAH溶液浓度从5×10~(-5) mol/L增加到10~(-3) mol/L时,低阶煤颗粒-气泡间的诱导时间从12 ms增加到35 ms。当DAH浓度由10~(-7) mol/L(纯去离子水溶液)增加到5×10~(-5) mol/L,低阶煤颗粒-油泡间的诱导时间由35 ms降低到10 ms。随着DAH浓度的进一步增加到10~(-3) mol/L时,低阶煤颗粒-油泡间的诱导时间由10 ms增加到25 ms。为了从微观尺度下去表征油泡表面较气泡表面所具有的强疏水性,本文通过低阶煤颗粒-油/气泡间的诱导时间,利用non-DLVO理论及Stefan-Reynolds水化膜薄化模型,拟合出初始水化膜厚度h与疏水性常数K_(132)之间的关系,进而得到了低阶煤颗粒-油/气泡间的疏水力常数K_(132)与十二烷胺盐酸盐DAH溶液浓度的关系。疏水力常数K_(132)拟合结果表明,当DAH溶液的浓度为5×10~(-5) mol/L时,低阶煤颗粒-油泡间的疏水力常数K_(132)约为低阶煤颗粒-气泡间的疏水力常数K_(132)的3倍;当DAH溶液的浓度为10~(-6) mol/L时,前者是后者的15倍。因此,油泡表面较气泡具有更强的疏水性质。从而解释了低阶煤-油泡浮选矿化过程优于传统浮选过程的本质特征。     

Effects of salinity on xanthate adsorption on sphalerite and bubble–sphalerite interactions

The adsorption of amyl xanthate on sphalerite in NaCl solutions of different concentrations and in saline water (viz. simulated sea water) and the surface properties of treated minerals were investigated. The interactions between xanthate treated sphalerite particles and air bubbles were examined using induction time measurement, which revealed that the salt ions could inhibit the adsorption of xanthate on sphalerite due to the competitive adsorption, but also could compress the electrical double layer at mineral/water interface. The induction time of sphalerite treated in potassium amyl xanthate (PAX) with saline water was shorter than that of sphalerite treated in PAX with NaCl of the same ion concentration, which implies that the water composition (e.g. Ca²⁺, Mg²⁺) could play an important role in the bubble–particle interaction. The hydrophobicity, chemical composition, and charge property of PAX treated sphalerite surfaces were characterized using contact angle measurement, Cryo-X-ray photoelectron spectroscopy (Cryo-XPS) and zeta potential determination, respectively, which support the inhibition effect of salt ions on the xanthate adsorption on sphalerite. In the case of saline water, the xanthate decomposition products were confirmed by XPS, which could further lower the hydrophobicity of the treated sphalerite. Our results provide insights into the basic understanding of the salinity effects on the xanthate adsorption on sphalerite and the bubble–mineral interactions in flotation.     

Application of reactive oily bubbles to bastnaesite flotation

Reactive oily bubble, defined as air bubbles covered with a thin layer of kerosene containing collectors, was used to float a major rare earth mineral, bastnaesite from rare earth ores. Both fatty acid and hydroxamic acid were used to generate reactive oily bubbles. The flotation of bastnaesite with reactive oily bubble was investigated by zeta potential, zeta potential distribution and induction time measurement and micro-flotation tests. The results showed a quicker attachment to bastnaesite and a stronger collecting power of reactive oily bubbles containing 100 ppm fatty acid than conventional air bubbles, resulting in an enhanced bastnaesite recovery. The flotation recovery of bastnaesite by reactive oily bubbles containing hydroxamic acid is lower than that by conventional air bubble flotation where the bastnaesite was pre-conditioned by hydroxamic acid in aqueous phase. During induction time measurement, no attachment is observed between bastnaesite particles and reactive oily bubbles containing hydroxamic acid, illustrating the importance of collector type in reactive oily bubble flotation technology. These findings suggest the superior performance of reactive oily bubble technique than conventional bastnaesite flotation method only when proper collector is used to generate the reactive oily bubbles.     

会泽铅锌硫化矿异步浮选新技术研究

通过单因素和正交浮选试验研究了会泽方铅矿、黄铁矿与闪锌矿之间的浮选分离。根据浮选动力学基本原理,对方铅矿和黄铁矿的浮选动力学特性进行了分析。结果表明,基于总体平衡理论的分速浮选模型可以较好地模拟方铅矿和黄铁矿的浮选过程,浮选回收率模型拟合值与试验值之间的相关系数R2均达到0.999。研究认为,异步浮选新技术充分利用不同矿物及同种矿物可浮性和浮游速度特性,实现矿物的个性化、差异性浮选。进一步探讨了异步浮选新技术的理论背景,对选矿人员完善已有工艺及开发新技术具有一定的参考意义。     

A model to relate the flotation rate constant and the bubble surface area flux in mechanical flotation cells

Two recent flotation models developed by the authors are discussed, viz. the bubble population balance model and the attachment-detachment model. The bubble population balance model describes the history of a bubble population in a flotation cell in terms of the sub-processes of bubble breakage and coalescence. The attachment-detachment model allows for the presence of a gas phase in the flotation cell, both in terms of a gas residence time and the attachment and detachment of mineral particles to/from bubbles. When combined the two models predict a near-linear region about a point of inflexion on the (simulated) response between the flotation rate constant (k) and the flux of bubble surface area through the flotation cell (S_b). It is proposed by the authors that this region corresponds to the linear k−S_b relationship observed in a recent research project on flotation kinetics in mechanical flotation cells by Gorain et al. (1997).     

乙硫氮作捕收剂时有机调整剂加药顺序对典型硫化矿物浮选的影响

研究了乙硫氮作为捕收剂时有机大分子调整剂糊精、腐殖酸钠、阳离子瓜尔胶和DP115(改性聚丙烯酰胺有机大分子)不同加药顺序对典型硫化矿物黄铜矿、方铅矿、闪锌矿和黄铁矿浮选行为的影响。单矿物浮选试验结果表明,有机大分子调整剂与捕收剂乙硫氮的加药顺序对硫化矿物浮选的影响不同。与调整剂先加相比,乙硫氮先加时,糊精对黄铜矿、方铅矿和闪锌矿浮选的抑制作用更强;腐殖酸钠对黄铜矿和方铅矿浮选的抑制作用不同程度增强,腐殖酸钠用量较低时对闪锌矿浮选的抑制作用减弱,而用量较高时则强烈抑制闪锌矿;阳离子瓜尔胶对黄铜矿和方铅矿浮选的抑制作用减弱,对闪锌矿浮选的抑制作用略强;DP115对黄铜矿浮选的抑制作用减弱,DP115用量低时对方铅矿浮选的抑制作用相当而对闪锌矿浮选的抑制作用减弱,用量较高时对方铅矿浮选的抑制作用更强而对闪锌矿浮选的抑制作用相当;糊精、腐殖酸钠、阳离子瓜尔胶和DP115对黄铁矿浮选的影响很小。研究结果可为部分硫化矿通过改变有机大分子调整剂与捕收剂的加药顺序提高矿物浮选分离的选择性和效率提供借鉴。     

Fundamental study of reactive oily-bubble flotation

A novel concept of reactive oily bubbles (i.e., bubbles covered by a thin layer of oil containing oil-soluble collectors) as a carrier in flotation is proposed. In addition to the role of fine particle agglomeration by oily films, the surface properties of air bubbles coated with a thin oil film can be better controlled for the desired selectivity by adding certain types and concentrations of water insoluble collectors into the oil phase. Oily bubbles attain a much higher contact angle than air bubbles, ensuring a strong collecting power, favorably for floating both coarse and fine particles. The reactive oily bubble flotation can eliminate the addition of collector to the aqueous phase, avoid undesired synergetic interactions among collectors, activators, depressants and dispersants present in slurry, minimize undesired activation of gangue particles and significantly reduce the amount of collectors needed.The electrokinetics of kerosene droplets in aqueous collector solutions was measured as a function of solution pH. The results clearly showed that the surface charge and hence the surface properties of oil droplets can be finely tuned by controlling the type of the collectors to suit the desired flotation needs. The attachment of collector-containing oily bubbles on silica, sphalerite and galena surfaces was investigated with contact angle measurement. The concept of using reactive oily bubble to achieve selective flotation was demonstrated in microflotation tests.     

矿物催化臭氧氧化乙硫氨酯的效率和矿化行为研究

浮选废水中残留固体悬浮物具有催化臭氧氧化作用，考察了四种硫化矿（黄铁矿、黄铜矿、方铅矿及闪锌矿）和四种非金属矿（石英、方解石、高岭土及蒙脱土）对臭氧氧化乙硫氨酯效率的影响及矿化行为。结果表明，矿物强化臭氧氧化乙硫氨酯降解效率高低顺序为方铅矿>黄铁矿>闪锌矿>黄铜矿（硫化矿）和高岭土>蒙脱土>方解石>石英（非金属矿），投加0.5 g/L方铅矿和高岭土后，乙硫氨酯降解速率常数分别提高了1.57倍和0.82倍，明显促进乙硫氨酯降解和中间产物的分解；降解后溶液pH值从10.0降至约8.0，氧化还原电位从-23 mV上升到约200 mV。矿物颗粒促进臭氧分解，生成更多强氧化性物种，提高降解效率，浮选废水中残留矿物颗粒是天然臭氧分解催化剂，可构成催化臭氧氧化体系。      

磨矿过程硫化矿物表面电化学性质及其对浮选的影响

本文根据浮选电化学理论分析讨论了丁黄药和乙硫氮在方铅矿、闪锌矿及黄铁矿三种硫化矿物表面的电化学作用过程,分析了磨矿环境具有低电位还原气氛产生的原因。腐蚀电偶测定结果表明,磨球介质与硫化矿物之间、方铅矿与黄铁矿之间的原电池相互作用减弱了黄铁矿表面的捕收剂作用过程,有利于方铅矿与黄铁矿的浮选分离。浮选试验结果表明利用磨矿过程进行浮选的工艺有较大的优越性     

Effect of impeller rotational speed on the size dependent flotation rate of galena in full scale plant cells

The first three rougher cells in the lead circuit of the Elura concentrator (formerly Pasminco Australia Limited) were selected as the plant cells for investigation. Metallurgical surveys were performed and various hydrodynamic measurements taken, allowing the galena flotation rate constant and the bubble surface area flux (S_b) in these cells to be calculated over a wide range of gas flow rates, and at two impeller rotational speeds. It was determined that altering the impeller rotational speed did not significantly change the rate constant dependency on S_b when flotation was considered on an unsized basis.The analysis was further extended to examine the same cells parameters on a size-by-size basis. The results obtained have been used to identify differences in the flotation behaviour of the various particle size fractions, independently of surface hydrophobicity. It is shown that the physical conditions for effective flotation of fine (<9 μm) and coarse (>53 μm) particle size fractions differ substantially, suggesting that a specific hydrodynamic environment will favour a high flotation rate for fine galena, which may be detrimental to the recovery of coarse galena, and vice versa. These observations are in accord with metallurgical practice that suggest that it is difficult to improve fine particle flotation without also compromising coarse particle stability efficiency simply by modifying the cell hydrodynamics alone. A fundamental flotation model was applied to quantify differences in the flotation rate of the various particle size fractions with impeller rotational speed.     

CFD modelling of bubble–particle attachments in flotation cells

In recent years, computational fluid dynamic (CFD) modelling of mechanically stirred flotation cells has been used to study the complexity of the flow within the cells. In CFD modelling, the flotation cell is discretized into individual finite volumes where local values of flow properties are calculated. The flotation effect is studied as three sub-processes including collision, attachment and detachment. In the present work, these sub-processes are modelled in a laboratory flotation cell. The flotation kinetics involving a population balance for particles in a semi-batch process has been developed.From turbulent collision models, the local rates of bubble–particle encounters have been estimated from the local turbulent velocities. The probabilities of collision, adhesion and stabilization have been calculated at each location in the flotation cell. The net rate of attachment, after accounting for detachments, has been used in the kinetic model involving transient CFD simulations with removal of bubble–particle aggregates to the froth layer.Comparison of the predicted fraction of particles remaining in the cell and the fraction of free particles to the total number of particles remaining in the cell indicates that the particle recovery rate to the pulp–froth interface is much slower than the net attachment rates. For the case studied, the results indicate that the bubbles are loaded with particles quite quickly, and that the bubble surface area flux is the limiting factor in the recovery rate at the froth interface. This explains why the relationship between flotation rate and bubble surface area flux is generally used as a criterion for designing flotation cells. The predicted flotation rate constants also indicate that fine and large particles do not float as well as intermediate sized particles of 120–240 μm range. This is consistent with the flotation recovery generally observed in flotation practice. The magnitude of the flotation rate constants obtained by CFD modelling indicates that transport rates of the bubble–particle aggregates to the froth layer contribute quite significantly to the overall flotation rate and this is likely to be the case especially in plant-scale equipment.     

Investigating fine galena recovery problems in the lead circuit of Mount Isa Mines Lead/Zinc Concentrator part 1: Grinding media effects

A plant survey was carried out on the lead secondary rougher and scavenger banks of the Lead/Zinc Concentrator of Mount Isa Mines Limited. Sizing analysis of the survey samples demonstrated that a major limiting factor to overall lead recovery in this section of the plant was the diminished recovery of the fine galena in the minus 5 microns particle size fraction. Batch flotation experiments were carried out on a plant sample of lead secondary rougher feed and a sample of rod mill feed ore. Mineral recovery-size data for these tests showed similar fine galena flotation behaviour to that observed in the plant. Increased collector addition did not improve either the maximum recovery or the flotation rate constant of the fine galena but did reduce the selectivity of galena against sphalerite. Changing of the grinding media used for the ore sample from a high carbon steel to a high chromium alloy steel resulted in a significant increase in the maximum recovery and flotation rate constant of the fine galena. EDTA (ethylene diaminetetraacetic) extractable iron measured for the high carbon steel media were similar in magnitude to those measured within the plant and were higher than those measured for the high chromium alloy steel media. The increased surface concentration of hydrophilic layers of oxidised iron species on the fine galena was a likely reason for their diminished flotation behaviour both in the laboratory and in the plant.     

浮选中颗粒-气泡间相对运动研究进展

颗粒-气泡间相对运动的研究对浮选机理的认知至关重要,对新型浮选机的开发和提高浮选效率均具有指导意义,本文系统综述了颗粒-气泡间相对运动的研究进展。早期研究过程中,研究者忽略了颗粒和气泡性质的影响,将颗粒视为随流线运动的点,气泡视为刚性球体,利用流线方程对颗粒-气泡间的相对运动展开研究;随着认知过程的不断深入,颗粒和气泡物理化学性质的影响逐步得到了关注,研究者分别从颗粒惯性力、重力、形状和粗糙度以及气泡表面流动性等方面并展开了大量研究;颗粒-气泡间相对运动的试验研究多通过颗粒沉降法进行,研究对象由单个玻璃微珠发展为大量矿物颗粒,且出现了关于运动玻璃球与上升气泡之间相对运动的研究。研究表明,当颗粒粒度较细、密度较小时,利用流线方程对颗粒-气泡间相对运动的研究具有一定的适用性;当颗粒粒度较粗、密度较大时,需考虑正负惯性力、重力等因素对颗粒-气泡间相对运动的影响。此外,颗粒形状的不规则性会影响颗粒周围液体对颗粒的作用力,导致临界碰撞半径减小,且颗粒表面不规则的凸起会促进颗粒-气泡间水化膜的破裂,减少诱导时间,增大颗粒表面粗糙度有助于增强颗粒-气泡间的黏附强度。气泡表面的流动性可采用"滞留帽"模型进行分析,具有较好的适用性。对于颗粒-气泡间相对运动的试验研究主要采用颗粒沉降法,亲水玻璃微珠只能在气泡上半球滑行,到达气泡赤道位置附近后便离开气泡,疏水玻璃微珠会刺破颗粒-气泡间的水化膜,越过气泡赤道后会继续沿气泡表面滑行并最终黏附在气泡底部,煤颗粒与气泡的黏附效率随碰撞角和密度的增大而减小。然而目前的试验研究多集中于静水领域,对于浮选流场中颗粒-气泡间相对运动的试验研究尚需进一步探索。     

乙硫氮作捕收剂时无机调整剂加药顺序对典型硫化矿物浮选的影响

研究了乙硫氮作捕收剂时无机调整剂硫酸锌、亚硫酸钠、硫化钠和硫酸铜不同加药顺序对典型硫化矿物黄铜矿、方铅矿、闪锌矿和黄铁矿浮选行为的影响。结果表明,调整剂与捕收剂的加药顺序对硫化矿物浮选的影响不同。与调整剂先加时相比,乙硫氮先加时,硫酸锌对黄铜矿和方铅矿浮选的抑制作用减弱;硫酸锌、低用量硫酸铜、亚硫酸钠或硫化钠对闪锌矿浮选以及硫酸铜对黄铜矿和方铅矿浮选的抑制作用更强;硫酸锌或硫酸铜对黄铁矿浮选以及较高用量硫酸铜对闪锌矿浮选的活化作用相当;亚硫酸钠或硫化钠对黄铜矿、方铅矿和黄铁矿浮选的影响很小。研究结果可为部分硫化矿通过改变调整剂与捕收剂的加药顺序提高矿物浮选分离效率提供借鉴。     

3-戊基-4-氨基-1,2,4-三唑-5-硫酮浮选分离黄铜矿与闪锌矿及其机理

考察了捕收剂3-戊基-4-氨基-1,2,4-三唑-5硫酮(AATT)对黄铜矿和闪锌矿的浮选分离性能,并通过接触角、紫外光谱、吸附动力学和热力学等研究了AATT浮选分离黄铜矿和闪锌矿的作用机理。结果表明,在pH>10.0时,AATT可实现黄铜矿与闪锌矿的高效浮选分离。AATT在黄铜矿表面的吸附过程符合准二级动力学吸附方程和Langmuir等温吸附模型,为自发、吸热的化学吸附过程。pH=10.5时,AATT能显著增大黄铜矿表面疏水性,但对闪锌矿表面疏水化作用不明显,从而实现黄铜矿与闪锌矿之间的浮选分离。     

A CFD-kinetic model for the flotation rate constant,Part II: Model validation

A Computational Fluid Dynamics (CFD) model was validated against published experimental data for the prediction of the flotation rate constant. An Eulerian–Eulerian framework was applied for modelling the multiphase flow inside a standard laboratory scale Rushton turbine flotation tank. The dispersed k–ε turbulence model simulated the turbulent effects inside the tank, while the collision, attachment and stability efficiencies were calculated using the local values of hydrodynamic parameters. Volume-weighted average flotation rate constants were simulated for chalcopyrite and galena and compared against published experimental data for the same physical setup. The results showed that both qualitatively and quantitatively the developed CFD-kinetic model can predict the flotation rate constants with an acceptable level of accuracy. Moreover, the validations of rate constants for the flotation of chalcopyrite and galena under various contact angles, agitation rates and gas flow rates confirmed the predictive capability of this numerical approach for further flotation modelling.     

Surface chemical studies on galena and sphalerite in the presence of Thiobacillus thiooxidans with reference to mineral beneficiation

Adsorption and electrokinetic studies were carried out to examine the surface chemical changes on galena and sphalerite before and after interaction with Thiobacillus thiooxidans (T. thiooxidans). The adsorption density of bacterial cells onto the two sulphide minerals was found to be independent of pH, although an increased number of cells was adsorbed onto galena compared to sphalerite. The adsorption isotherms of the cells with respect to the two minerals conform to the Langmuir equation. Zeta potential measurements revealed that the isoelectric points of the sulphide minerals were shifted to higher pH values after bacterial interaction, suggestive of specific adsorption. Both the sulphide minerals as well as the cells became less electronegative as a function of time after interaction with each other. Selective flotation and flocculation studies highlighted that galena could be separated from sphalerite after bacterial interaction. These tests confirmed that galena was depressed while sphalerite was made hydrophobic after interaction with the cells. Fourier transform infrared spectroscopic studies provided evidence in support of hydrogen bonding for the mineral-cell adsorption process. Possible mechanisms of interaction between galena/sphalerite and the cells of T. thiooxidans are discussed.     

Combinations of different-class collectors in selective sulphide-ore flotation

The paper discusses laboratory test data on well-known sulphydryl collectors and new modified dithiophosphates Beraflot used to float monomineral fractions of pyrite, chalcopyrite, galena, and sphalerite. Frothless flotation is employed in flotation tests, IR-spectroscopy is used to identify surface compounds, and technological investigations are based on froth flotation. It is shown that dimethyl dithiocarbamate, isobutyl dithiophosphate and modified collector Beraflot-3035 give the poorest results of pyrite flotation, while Beraflot-3035 provides the highest galena and chalcopyrite recovery. It is found that Beraflot-3035 is capable to form different surface compounds on pyrite, chalcopyrite, galena, and sphalerite. Unclosed ore tests verify selectivity of Beraflot-3035.