气泡、油泡和活性油质气泡在浮选中的应用和机理探讨

浮选是高效回收矿产资源应用最广泛的技术方法。气泡作为浮选载体在浮选过程中有着举足轻重的作用。以气泡-油泡-活性油质气泡为线索,对比了传统气泡与改性后油泡(气泡表层包裹一薄层油性捕收剂)、活性油质气泡(气泡表层包裹一薄层含有捕收剂的中性油)的浮选特性。通过浮选动力学分析了气泡与油泡、活性油质气泡浮选的区别,传统气泡浮选与改性后的油泡浮选均为2步反应,而活性油质气泡实现了1步浮选,大大降低了气泡与矿物颗粒间的黏附功,提高了浮选效率。从油-水界面表面活性剂解离度这个角度分析了活性油质气泡的表面性质,指出活性油质气泡的表面电性由表层中性油中添加的捕收剂和p H决定。通过DLVO理论计算了不同气泡与矿物颗粒间的相互作用能,从理论上解释了活性油质气泡浮选指标更好的原因。活性油质气泡在选矿中的成功应用表明,活性油质气泡与矿物表面的作用均强于传统气泡与矿物表面的作用,即活性油质气泡对矿物具有更强的捕收能力,相较于气泡和油泡的浮选,活性油质气泡浮选有利于提高浮选效率,降低捕收剂用量。活性油质气泡作为浮选载体从气泡这一特殊视觉为浮选行业开辟了一个崭新的研究领域。     

一种氟碳铈矿捕收剂的设计筛选及浮选性能研究

以氟碳铈矿为研究对象,研究了以羟肟酸、苯乙烯膦酸、邻苯二甲酸用作捕收剂时的浮选效果。研究结果表明：借助于CAMD技术研发的捕收剂羟肟酸类捕收剂BK415可以有效浮选氟碳铈矿,浮选效果优于H205、苯甲羟肟酸、水杨羟肟酸、邻苯二甲酸等,是一个很有前途的稀土捕收剂。     

油泡-低阶煤颗粒间的黏附特性

在浮选矿浆中矿物颗粒能够有效地黏附在气泡上完成矿化过程是浮选技术的关键。用油泡代替气泡,研究难浮低阶煤颗粒与油泡间的相互作用及其黏附特性对于弄清其矿化机制至关重要。从矿物表面电性入手,探究了溶液p H值和表面活性剂对煤样与油泡间作用力的影响,运用DLVO理论计算了相互作用力的大小,并通过诱导时间这一重要参数评价了黏附效率。实验结果表明,DLT煤样和油泡的等电点分别出现在p H值2~3和p H值3~5之间;当p H=3时溶液中煤样与油泡之间的相互作用不存在能垒;p H3时开始出现能垒,并随p H值的增大而增大。2-乙基己醇和双十二烷基二甲基溴化铵的加入能够有效地减小煤样与油泡之间的能垒并降低诱导时间,最大降幅分别为74.35%和86.45%。     

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...     

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。     

羟肟酸协同脂肪酸分离磷灰石和白云石

针对脂肪酸浮选磷矿石存在选择性不强、常温下脂肪酸流动性和分散性差、浮选过程需要加温等不足,考察了羟肟酸协同脂肪酸作用时对溶液黏度、表面张力、ζ电位的影响。结果显示：脂肪酸低温下流动性较差,黏度受温度和搅拌强度影响较大,羟肟酸与脂肪酸混合能有效降低脂肪酸黏度;随着脂肪酸和羟肟酸用量的增加,溶液表面张力均逐渐降低,烷基羟肟酸与脂肪酸混合作用较单一药剂作用时溶液表面张力降低;脂肪酸用量为400 mg/L、烷基羟肟酸添加量为脂肪酸的0.5倍、pH=6时,白云石与磷灰石表面电位差最大。白云石和磷灰石单矿物浮选试验结果表明,脂肪酸用量为400 mg/L、烷基羟肟酸添加量为脂肪酸的0.5倍、pH=6时,白云石与磷灰石回收率差值达到87.88个百分点,比未添加烷基羟肟酸时的差值提高了14.34个百分点,添加烷基羟肟酸可以改善磷灰石和白云石的分离效果。红外光谱分析表明,混合捕收剂与白云石发生物理吸附和化学吸附,与磷灰石只有少量的物理吸附。羟肟酸|脂肪酸|协同作用|磷灰石|白云石|浮选     

Biosorptive flotation of copper ions from dilute solution using BSA-coated bubbles

Copper adsorption was carried out using the novel material known as air-filled emulsion (AFE). AFE is a stable colloidal system containing microscopic protein-coated bubbles (<10 μm) dispersed through an aqueous solution, resulting in an increased specific surface area and contact time between extractant and metal ions. Bovine serum albumen (BSA) generated emulsion concentration had a significant impact on copper removal, with maximum metal uptake obtained at 2.5 g/l of BSA-coated bubbles. It was shown that copper sorption was rapid over the first 10 min, and equilibrium conditions were reached within 40 min. Separation of the copper-loaded microcells from the aqueous solution was also investigated. Micro-flotation was employed to remove the microbubbles by means of attachment to the surface of larger air bubbles. In absence of a cationic surfactant, approximately 0.5% copper recovery was obtained at pH ranging from 5 to 8 due to the lack of hydrophobic groups on the surface of Cu-loaded BSA emulsions. Due to the fine sizes of the emulsion bubbles (<10 μm) a cationic flocculant was used to induce coagulation of the bubbles leading to easier phase separation. A combination of collector and flocculant at a concentration of 3 × 10⁻⁴ M and 0.025 g/l, respectively, led to an increase in copper recovery to nearly 35% at pH 7.     

混合药剂对浮选柱中气泡性质及其分散特征的影响

为研究十二胺和仲辛醇对浮选柱内气泡性质及其分散特征的影响,利用图像分析法测定了气泡的粒径分布,分别采用表面张力仪和量筒法测定了表面张力和充气量,并进一步分析了气泡的吸附密度和表面积通量。研究表明,随着十二胺和仲辛醇药剂浓度的增大,气泡粒径逐渐减小并在达到临界兼并浓度后分别稳定在0. 630 3和0. 602 0 mm,其中气泡粒径衰变程度为99%时,十二胺L,相同药剂浓度时,十二胺溶液中的气泡尺寸大于仲辛醇溶液的;溶液的表面张力随着药剂浓度的增大而线性减小,相同药剂浓度时,十二胺溶液的表面张力低于仲辛醇溶液;充气量随着药剂浓度的增大而逐渐增大,相同药剂浓度时,十二胺溶液的充气量大于仲辛醇溶液。在临界兼并浓度时,十二胺和仲辛醇在气泡表面吸附密度分别为/m2,仲辛醇的气泡表面积通量大于十二胺。随着仲辛醇溶液中十二胺添加量的增大,气泡临界兼并浓度和稳定粒径均逐渐减小,其中十二胺添加量为0. 032 4 mmol L,气泡稳定粒径也达到最小值为0. 583 3 mm;表面张力和吸附密度均随着十二胺添加量的增大而逐渐减小,其中十二胺添加量为L时,气泡表面药剂吸附密度达到最小值0. 154 0μmol量均随着十二胺添加量的增大而逐渐增大,当添加量为0. 032 4 mmol最大值7. 734 s~(-1)。     

浮选柱技术的应用现状及发展趋势

相比于传统浮选机,浮选柱具有结构简单、易于调控、浮选效率高等优势,更适于处理品位低、嵌布粒度细、矿物组成复杂的矿石资源,其研究和应用逐渐成为矿物加工领域关注的焦点。介绍了浮选柱的发展历程和分类,重点阐述了各种新型浮选柱CPT浮选柱、Jameson浮选柱、充填型浮选柱、旋流-静态微泡浮选柱、CCF浮选柱、KYZ浮选柱、CFC浮选柱在矿物浮选中的应用现状,通过与浮选机的浮选指标对比,在处理微细粒难选矿物时,浮选柱具有常规浮选机所不可比拟的分选效果;同时归纳了电解浮选技术、磁浮选技术、流态化浮选技术与柱浮选技术结合的代表性浮选设备—磁浮选柱、电解浮选柱、流态化浮选柱等的应用进展;最后,指出了浮选柱的未来研发方向应侧重于自动控制系统的完善、流体动力学数值模拟的研究以及与综合力场的结合等方面。     

Detachment of coarse composite sphalerite particles from bubbles in flotation: Influence of xanthate collector type and concentration

The force required to detach sphalerite ore particles from air bubbles has been measured in flotation concentrates, for particles in the size range of 150–300 μm and 300–600 μm with different degrees of liberation. An electro-acoustic vibrating apparatus, that produces typical force conditions experienced in a flotation cell, was used to measure particle–bubble detachment as a function of the vibrational acceleration. Sodium isopropyl xanthate (SIPX) and potassium amyl xanthate (PAX) collectors were used in flotation, at different concentrations. At a fixed frequency of 50 Hz, the maximum vibrational amplitude at which a particle detaches from bubble was used to calculate the particle detachment force. It was shown that changes in surface hydrophobicity (contact angle), due to variations in reagent conditions have significant impact on particles detaching from bubbles. On average, detachment of particles from oscillating bubble correlated well with xanthate concentration and hydrocarbon chain length of xanthate ions. Particles (300–600 μm) with high contact angle obviously required higher force to detach from bubbles than similar particles with lower contact angle. This correlated well with the flotation response at the different reagent conditions. SEM analysis of particles after detachment showed that fully liberated particles attached to bubbles more readily and also gave higher detachment force than composite particles. Moreover larger detachment forces were observed, on average, for particles with irregular shape compared to particles with rounded shape of the same size range.     

大直径旋流微泡浮选柱的研究及应用

针对细粒浮选中精矿污染形成的主要原因煤泥浮选特点,主要分析了旋流旋泡浮选柱综合利用微泡浮选、逆流浮选、旋流离心力场强化分选的机理,并介绍了旋流微泡浮选柱的结构、特点及工业应用的效果。     

Examination of NaCl and MIBC as bubble coalescence inhibitor in relation to froth flotation

With scarcity of fresh water resources, flotation plants are increasingly under pressure to supply their water needs from other sources such as bore water, seawater or recycled plant water. This water generally contains a high concentration of inorganic electrolytes which may have a substantial influence on the performance of the flotation operation. In this study, the stabilisation mechanism of bubbles by salt was investigated using a specifically designed experimental set-up. Two bubbles of approximately the same size were produced at the tip of two adjacent capillaries in concentrated solutions of an inorganic electrolyte (NaCl). Their coalescence behaviour was recorded using high speed video imaging in which information such as coalescence time and deformation of the resultant bubble upon coalescence could be extracted. The results were then compared against a similar system using MIBC. It was found that delayed coalescence in NaCl required a relatively concentrated solution in the order of 0.1-0.5 M to achieve coalescence times comparable to MIBC. Unlike NaCl, it appears that a small amount of MIBC, in the order of 10⁻⁵ M, is sufficient to delay the coalescence of bubbles, which reach a maximum at a concentration of 3 × 10⁻³ M. The analysis of oscillation patterns during the coalescence process revealed that the oscillation is noticeably damped in the presence of MIBC at high concentrations, although this is not the case in NaCl solutions. Results are discussed in terms of bubble stability, froth stability and their possible implications on particle recovery.     

Towards a new process for the flotation of quartz

Results obtained from flotation experiments performed on three different quartz concentrates demonstrate that quartz can be floated in diluted solutions of hydrofluoric acid (HF) simply by the aid of frothers alone. The recovery was found to be highly dependent on the choice of frother and strongly positively correlated with the concentration of both frother and HF, as well as with the HF conditioning time. Experiments using HNO₃ instead of HF showed no flotation of quartz. Of the five different frothers tested, Brij 58 was found to produce the highest recovery. Good recoveries were also obtained for Dowfroth 400 and Flotanol C07, whereas Dowfroth 200 and MIBC failed to float any quartz. From experiments in which a given feed material were tested at two different particle size distributions it was found that highest recoveries were obtained for the finer feed. Chemical analysis of the floated products showed that these were significantly purer than their corresponding feed materials, and that most of the contaminating elements were concentrated in the sink fraction that remained in the cell. Contact angle measurements corresponded well with flotation recoveries.     

Geometrical optimization of xanthate collectors with copper ions and their response to flotation

Quantum chemical calculations have been employed to understand the nature of interaction between xanthate and Cu—as part of an ore and Cu—as part of a slag. A semi-empirical parameterized model, (PM3) is used to study ethyl xanthate, propyl xanthate, iso-propyl xanthate, iso-butyl xanthate and amyl xanthate. The total interaction energy, E, is interpreted in terms of the highest occupied molecular orbital (HOMO) energy of the individual collectors with copper ions. The electron density map along with the change in heat of formation, binding energy and dipole-moment, indicate that amyl-xanthate binds to surface of copper ions strongly in comparison to other xanthates. The numerical results obtained with potassium amyl xanthate also support the experimental data on recovery of copper values from a copper ore by flotation.     

电解质对低阶煤油泡浮选矿化过程的影响

浮选矿浆中离子的种类与浓度直接影响着矿物颗粒和气泡的表面电位,进而支配着浮选矿化过程。从热力学和动力学两个方面入手,通过DLVO理论探究了不同电解质对煤粒和油泡间的相互作用势能的影响,结合其在不同电解质条件下诱导时间的差异,最终通过相应条件下的油泡浮选试验来证实电解质对低阶煤-油泡浮选矿化黏附过程的影响。结果表明:对于NaCl和CaCl_2两种电解质,随其浓度的增大,煤粒和油泡表面电位的负值均不断减小,煤粒和油泡间的能垒也不断降低,当CaCl_2浓度为100 mmol/L时,煤粒和油泡间的相互作用不存在能垒;并且随这两种电解质浓度的增大,黏附过程的诱导时间逐渐减小,相应地可燃体回收率不断提高,且相同的电解质浓度下,CaCl_2电解质对其相互作用能垒和诱导时间的降低程度更大,可燃体回收率更高。而对于AlCl_3电解质,当其浓度大于20 mmol/L时且随浓度的增大,煤粒和油泡间的相互作用能垒和诱导时间不断增大,相应地可燃体回收率则不断降低。     

The DFT study of cyclohexyl hydroxamic acid as a collector in scheelite flotation

In this paper, cyclohexyl hydroxamic acid (CHA) was investigated as a new collector for scheelite flotation by the Density Functional Theory (DFT) calculation, mineral flotation tests, adsorption measurement and zeta potential determination. The DFT computation results indicated that the dianion of CHA or benzoylhydroxamic acid (BHA) exhibited stronger chemical reactivity than their anions and neutral molecules, and that the replacement of phenyl group by cyclohexyl group in BHA molecule significantly impacted the electron donating ability of hydroxamate collectors. In alkaline aqueous solutions, the two oxygen atoms in the dianions of CHA or BHA charged more negative charges than other atoms, and hence became their reactive center. The dianion of CHA exhibited higher atomic charge value, HOMO (Highest Occupied Molecular Orbital) energy, bigger dipole moment and binding energy with Ca²⁺, thus it had stronger collecting ability for scheelite than that of BHA. In addition, the results of flotation tests, adsorption measurement and zeta potential determination validated that the collecting capability of CHA was stronger than that of BHA, which achieved excellent agreement with computational analysis.     

有机双膦酸对独居石浮选的作用机理研究

通过浮选试验、Zeta电位、红外光谱分析及溶液化学计算,研究了有机双膦酸对独居石浮选的作用机理.结果表明,独居石浮选的最佳条件为矿浆pH值为7和有机双膦酸用量为0.04 mmol/L.不同粒级浮选效果不同,细粒级独居石泥化严重,浮选效果较差.有机双膦酸水解产生的优势组分H2L2-和HL3-可与独居石矿物表面暴露的稀土离...     

Reasonable reduction in hydrophoby of mineral surface on flotation by carboxylic acids

Numerical estimation of the effect of surfactants on floatability of particles with different wettability is reported. It is proved that the particles with higher hydrophilic surface are recovered into a froth product at the “gas-pulp” interface at the presence of a film of normal alcohols and fat acids. Theoretical value of the suppression coefficient for the capillary wave amplitude coincides satisfactorily with the test values and may be used in calculations. __________ Translated from Fiziko-Tekhnicheskie Problemy Razrabotki Poleznykh Iskopaemykh, No. 5, pp. 90–99, September–October, 2006.     

Application of three-dimensional electrical resistance tomography to characterize gas holdup distribution in laboratory flotation cell

Flotation is a separation process in which a hydrophobic material is separated from a hydrophilic one. It is commonly used in several branches of processing. The purpose of this paper was to use three dimensional Electrical Resistance Tomography (ERT) for the measurement of the spatial distribution of gas holdup in a mechanical flotation cell. Using an array of metal electrodes installed on the wall of the cell, a set of electric currents was injected to the cell and the resulting voltages were measured. The electrical conductivity within the cell was estimated based on the known currents and measured voltages. The gas holdup distribution was computed based on Maxwell model. The method was tested in a 50 dm³ mechanical flotation cell filled with water. The gas holdup distribution is presented at various values of the rotor speed and gas superficial velocity in non-frothed and frothed cases. Moreover, the performance of two rotor-stator mechanisms was compared. The results indicate that the 3D gas holdup distribution in a mechanical flotation cell under different conditions can be estimated using ERT. Moreover, differences in the gas holdup distribution can be detected depending on which rotor-stator mechanism is in use.