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.     

酸预处理对六方晶系磁黄铁矿浮选行为的影响及作用机理

针对磁黄铁矿易氧化且氧化后可浮性差、难以通过浮选将其与其他矿物分离的问题,通过单矿物浮选试验、接触角测量、Zeta电位测定以及红外光谱测试等方法研究了酸预处理对不同氧化程度六方晶系磁黄铁矿浮选行为的影响及作用机理。结果表明,六方晶系磁黄铁矿氧化程度越深,其可浮性越差; 通过酸预处理可以明显提高六方晶系磁黄铁矿可浮性,且酸预处理pH值越低,酸预处理后六方晶系磁黄铁矿可浮性越好; 酸预处理后的六方晶系磁黄铁矿接触角明显增大,疏水性得到提高,零电点向负方向偏移,表面带正电的氧化产物发生脱附; 红外光谱测试结果表明,丁基黄药与六方晶系磁黄铁矿发生化学吸附同时生成双黄药。     

Impact of gypsum supersaturated water on the uptake of copper and xanthate on sphalerite

Gypsum supersaturated process water has been shown to have an adverse effect on the flotation of sphalerite minerals. This study probes the mechanism of such effect by determining the uptake of copper and xanthate on sphalerite in gypsum supersaturated water using zeta potential distribution measurement, atomic absorption spectroscopy, UV–visible spectroscopy and quartz crystal microbalance with dissipation. Our results indicate that the supersaturation of water by gypsum retards the adsorption of copper and hence the sequence xanthate adsorption on sphalerite. The retardation of copper and xanthate adsorption on sphalerite is also observed by the addition of 800 ppm calcium. The adsorption of calcium is identified to compete with copper species for the reactive surface sites of the sphalerite, resulting in the reduction in copper and xanthate uptake and hence flotation recovery of sphalerite.     

Pulp potential and floatability of chalcopyrite

Contact angle measurements, ultraviolet (UV) spectroscopy and microflotation studies were carried out in order to investigate the effect of externally applied potential on the wettability of both synthetic and natural chalcopyrites in potassium amyl xanthate (PAX) solutions. The contact angle on the mineral electrode surface was measured after the mineral electrodes were conditioned at a fixed potential for 10 min. The effects of pH, concentration of PAX and depressants such as sodium cyanide, sodium sulfide and MAA (a mixture of magnesium chloride, ammonium chloride and ammonium hydroxide) on the contact angle of synthetic and natural chalcopyrites were also investigated. The hydrophobic film on the chalcopyrite surface was extracted using hexane and examined by UV spectroscopy. Collector and collectorless microflotation of natural chalcopyrite under controlled potential at pH 10 was performed in order to determine the floatable potential range of chalcopyrite. The contact angle results indicated that synthetic and natural chalcopyrites have similar wettability. Their floatable potential range in 7×10⁻⁴ M PAX solution was −0.2 to 0.2 V vs. standard calomel electrode at pH 10 and was −0.25 to 0.3 V at pH 7. Sodium sulfide showed the strongest inhibiting effect among the three depressants investigated. The flotation results indicated that natural chalcopyrite floated in the pulp potential range of −0.087 to +0.2 V (vs. SCE and monitored by a platinum electrode) without collector and in the potential range of −0.2 to +0.205 V in the 7×10⁻⁴ M PAX solution.     

Mechanism for the recovery of silicate gangue minerals in the flotation of ultrafine sphalerite

The effect of copper sulphate and sodium isopropyl xanthate on the flotation of a mixed mineral system has been studied at pH 9. The mixed mineral system was composed of colloidal silica and ultrafine sphalerite particles. Batch flotation, zeta potential and rheology have been applied to identify mechanisms by which the silica may misreport to a sphalerite concentrate. The results indicate that, in the absence of both copper sulphate and xanthate, silica was recovered essentially by the entrainment mechanism. However, the addition of copper sulphate and isopropyl xanthate increased particle interactions between silica and sphalerite, promoting aggregation. Consequently, silica may misreport to the concentrate via a combination of both entrainment and aggregation mechanisms. Under the conditions applied in the present study, silica is not likely to be recovered via true flotation, i.e. by attachment of silica particles to bubbles.     

Mechanism of adsorption of sodium dodecylsulfonate on celestite and calcite

The surface properties of celestite (SrSO₄) and calcite (CaC0₃) in aqueous solutions of the anionic collector sodium dodecylsulfonate (NaDDS0₃) have been investigated making use of zeta potential, adsorption, infrared spectroscopy and microflotation techniques. A range of pH (3 to 11) and surfactant concentration (10⁻⁶ to 10⁻³ M) were tested. The experiments were performed at a constant temperature (25°C) and using regulated suspensions. The zeta potential studies showed that the isoelectric point (IEP) of celestite and calcite took place at pH 3 and 8, respectively. In the presence of dodecylsulfonate ion the IEP of both minerals shifted to lower pH values. The adsorption isotherms obtained for both minerals showed marginal adsorption up to certain surfactant concentration and precipitation of the salt (strontium or calcium dodecylsulfonate) onto the mineral surface beyond such a concentration. The microflotation studies showed that celestite was activated even at pH values where its surface was negatively charged. Compared to celestite, the activation of calcite was lower. It is suggested that the dodecylsulfonate ion adsorbed on the surface of celestite and calcite by a chemisorption mechanism giving rise, under certain circumstances, to the formation of the corresponding salt at the mineral-water interface.     

影响典型铜矿物可浮性的晶体化学基因研究

为实现“基因矿物加工”系统工程建设,探究基因特征与铜矿浮选的关系,以具有代表性的铜矿物黄铜矿、斑铜矿、孔雀石、蓝铜矿和赤铜矿作为研究对象,通过 XPS、溶解性试验、Zeta 电位、接触角等测试分析及 MS 模拟计算等分析总结了含铜矿物的基因特征。通过浮选试验得到了含铜矿物的天然可浮性为：斑铜矿>黄铜矿> 赤铜矿>孔雀石>蓝铜矿;在乙基钠黄药（NaEX）、丁基钠黄药（NaBX）、异戊基黄药（NaIAX）和丁铵黑药体系下的浮选规律为黄铜矿、斑铜矿有较好的可浮性,而孔雀石、蓝铜矿和赤铜矿的可浮性较差,可浮性优异大致规律为：斑铜矿>黄铜矿>蓝铜矿≈孔雀石>赤铜矿;结合基因特征分析得出含铜矿物的天然可浮性规律与断裂面、断裂键密度和断裂键等基因特征有关,而在 NaEX、NaBX、NaIAX 和丁铵黑药体系下铜矿物的可浮性规律与铜矿物的禁带宽度和表面 S 元素含量基因特征有关。     

药剂在锌硫分离过程中的竞争吸附机制研究

通过人工混合矿浮选实验和润湿接触角测试, 考察了闪锌矿与磁黄铁矿浮选分离的影响因素, 并研究了浮选药剂在矿物表面的吸附机制。结果表明 磁黄铁矿影响闪锌矿的浮选并显著降低浮选锌精矿品位。捕收剂与抑制剂在两种矿物表面发生了竞争吸附 在闪锌矿表面, 丁基黄药的吸附能力要强于腐植酸钠;而在磁黄铁矿表面, 腐植酸钠的吸附能力要强于丁基黄药。研究结果表明, 适宜用量的捕收剂配合抑制剂可以较好地实现锌硫浮选分离。     

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。     

The use of ToF-SIMS and microflotation to assess the reversibility of binding of CMC onto talc

Carboxymethyl cellulose (CMC) is commonly used as a depressant for talcaceous minerals. To assess whether CMC depressants are strongly, or weakly and reversibly bound to the surface of talc, desorption experiments were conducted on New York talc. The floatability was monitored through microflotation experiments, combined with the determination of the CMC coverage on talc by ToF-SIMS. CMC adsorption and desorption were carried out in distilled water and in electrolyte containing Ca²⁺ ions. CMC adsorption levels were higher using Ca²⁺ electrolyte, in line with the depression behavior in the microflotation tests. Washing did not affect the flotation behavior. ToF-SIMS showed that CMC coverage of the talc particles was good and the distribution homogeneous. Adsorption and subsequent desorption in distilled water however, showed a partially restored floatability after desorption, which could be related to an inhomogeneous CMC distribution on the talc surface as shown by ToF-SIMS. By additional exposure to Ca²⁺ ions CMC redistribution occurs causing depression.     

Increase in contrast of wettability of the sulfide minerals in Copper-Zinc ores during flotation and flocculation

Consideration is given to the influence exerted by styrene-butadiene copolymer on wettability of the surface of pyrite, sphalerite, and chalcopyrite as well as on flocculation and floatability of mineral slimes. It is established how pH and styrene-butadiene copolymer combined with xanthate affect the change in hydrophoby of the sulfides in question and the processes of flocculation and flotation. The conditions are determined for the improvement in contrast of properties of separated minerals.Translated from Fiziko-Tekhnicheskie Problemy Razrabotki Poleznykh Iskopaemykh, No. 3, pp. 95–100 May–June, 2004.     

Impact of gypsum supersaturated solution on surface properties of silica and sphalerite minerals

In some sulphide mineral flotation operations, the process water contains high concentrations of calcium and sulphate ions that exceed the solubility limit of gypsum. It has been speculated that the gypsum supersaturated process water would lead to precipitation of gypsum which could coat on mineral surfaces by either nucleation or coagulation, resulting in reduced flotation recovery and selectivity. In this study, a laboratory prepared gypsum supersaturated solution is used to represent the gypsum supersaturated process water, the effect of gypsum supersaturated solution on the surface properties of silica and sphalerite minerals was investigated using zeta potential distribution measurements, scanning electron microscope (SEM), X-ray photon spectroscopy (XPS), Auger electron spectroscopy (AES), and quartz crystal microbalance with dissipation (QCM-D). Our results show that silica and sphalerite minerals carry identical surface charge (−10 mV of zeta potential) in the gypsum supersaturated solution at pH 10 although they are charged differently in simple electrolyte solution at the same pH. Needle shape gypsum precipitates are found in both silica and sphalerite minerals systems conditioned with gypsum supersaturated solution. The gypsum precipitates do not grow on the minerals surfaces but form in the bulk gypsum supersaturated solution. The heterocoagulation between the examined minerals and gypsum particles is insignificant in the gypsum supersaturated solution. It is the high calcium concentration in the gypsum supersaturated solution that has significant effect on the surface properties of silica and sphalerite minerals. The zeta potentials of silica and sphalerite in a 800 ppm calcium solution (similar to the calcium concentration in the gypsum supersaturated solution) are similar to those measured in the gypsum supersaturated solutions. Both silica and sphalerite minerals surfaces are indiscriminately coated with calcium. The surface coating of calcium results in the identical surfaces between silica and sphalerite minerals, and ultimately causes problems for the flotation separation of silica and sphalerite.     

Surface characterisation,collector adsorption and flotation response of enargite in a redox potential controlled environment

We previously investigated oxidation of the surface of natural enargite (Cu₃AsS₄) under potentiostatic control and the formation of oxidation species at the mineral surface at selected applied potentials in the oxidative range. Here we further extended the research by incorporating flotation collectors into the system. Electrochemical techniques, X-ray photoelectron spectroscopy (XPS) and microflotation in a redox potential controlled environment were applied to examine surface properties, collector adsorption and flotation response of enargite in pH 10 solutions of sodium ethyl xanthate (SEX) and sodium dialkyl dithiophosphinate (3418A). The spectral details of XPS analysis of electrochemically treated enargite surfaces show significant adsorption of SEX and 3418A collectors onto enargite at an applied voltage of +516 mV, but no adsorption of both collectors at −400 mV. The results of XPS analysis agree with the floatability of enargite determined by microflotation, showing that the flotation recovery was highest at high oxidative potential (+516 mV), then decreased at low oxidative potential (+100 mV) and was very poor at −400 mV. These results confirm that enargite floatability can be efficiently controlled electrochemically.     

黄药类捕收剂与载金黄铁矿的作用机理研究

研究了黄药类捕收剂在载金黄铁矿表面上的吸附机理。浮选试验结果表明, 乙黄药、丁黄药和Y-89用量为20～40 mg/L时, 载金黄铁矿上浮率能达到80%~90%; 矿浆pH值对载金黄铁矿可浮性影响较大, 在pH=4～8条件下, 载金黄铁矿可浮性较好, pH>8后, 可浮性下降; 黄药类(乙黄药、丁黄药、Y-89)捕收剂对亚铁离子具有较好的选择性, 对金离子选择性较小。吸附量试验结果表明, 捕收剂在载金黄铁矿表面吸附量随着药剂浓度增大基本呈线性增加, 且随着pH值增加逐渐降低, 在酸性条件下, 吸附量较大, 当pH>8后, 吸附量快速降低。载金黄铁矿与黄药类捕收剂作用前后的红外光谱表明, 捕收剂在载金黄铁矿表面产生了吸附。     

脆硫锑铅矿与乙基黄药相互作用电化学浮选红外光谱研究

考察了乙基黄药为捕收剂时,脆硫锑铅矿的浮选行为,发现在pH2￣12的范围内,脆硫锑铅矿均可表现良好的可浮性,只有pH>12时,可浮性下降。通过用氧化剂过硫酸铵、还原剂硫代硫酸钠调节矿浆电位,考察了脆硫锑铅矿在不同pH值下,可浮性与矿浆电位的关系,得出了矿物可浮的电位-pH区间。并通过红外光谱测试的研究,探讨了乙基黄药在脆硫锑铅矿表面作用机理及生成产物,不同pH值及不同电位下与乙基黄药作用后,脆硫锑铅矿浮选回收率与红外吸收强度有一定的对应关系,在弱酸性范围,红外信号最强。乙基黄药在脆硫锑铅矿表面作用主要生成物为黄原酸铅。     

Effect of contact angle,surface tension and zeta potential on oil agglomeration of celestite

The influences of contact angle, surface tension and zeta potential on oil agglomeration recovery of celestite mineral have been investigated in the present work. Therefore, celestite mineral in methanol–water suspension was agglomerated by the use of oil (kerosene) in the presence of sodium oleate as a surfactant. The zeta potential values of celestite surfaces were measured depending on pH and sodium oleate concentration. The zeta potential values of celestite surfaces became negative even more owing to the sodium oleate adsorption. However, this phenomenon did not affect the oil agglomeration recovery at all. It was found that both increasing contact angle and surface tension raised the oil agglomeration recovery of celestite mineral. Eventually, the agglomeration degree of celestite mineral in the suspension was not lower than a particular surface tension value corresponding to the critical solution surface tension for oil agglomeration (γ_c-a). The γ_c-a values were slightly greater than the critical surface tension of wetting (γ_c) values.     

巯基乙酸抑制硫化矿物的电化学机理研究

研究了巯基乙酸（TGA）对硫化矿物电极电位和动电位的影响。试验表明巯基乙酸对黄铁矿、方铅矿和黄铜矿有抑制作用,对毒砂和亲锌矿没有抑制作用。电化学测试表明巯基乙酸对表面覆盖有捕收剂膜的硫化矿物动电位影响较小,能够显降低硫化矿物的静电位,它对硫化矿物抑制的电化学机理为当硫化矿物的静电位EMS低于黄药氧化为双黄药的可逆电位EX^-/X2时,硫化矿物表面双黄药不稳定被还原,从而降低了可浮性;反之,双黄药保持稳定,不被抑制。用巯基乙酸实现两种硫化矿物浮选分离的电化学条件为：EMS1＜EX^-X2(EX^-/GPbX2）＜EMS2。     

磁黄铁矿与乙黄药相互作用电化学浮选红外光谱的研究

考查了乙黄药为捕收剂时磁黄铁矿的浮选行为, 发现在pH=1～12 范围内, 磁黄铁矿均表现出良好的可浮性, 只有当pH >12 时, 可浮性下降。通过用氧化剂过硫酸铵, 还原剂硫代硫酸钠调节矿浆电位, 考查了磁黄铁矿在不同pH 值下, 可浮性与矿浆电位之关系, 得出了矿物可浮的电位-pH 区间。并通过红外光谱测试的研究, 探讨了乙黄药在磁黄铁矿表面作用机理及生成产物, 不同pH 值及不同电位下与乙黄药作用后, 磁黄铁矿红外吸收强度与其回收率有对应关系, 双黄药是主要吸附产物。     

糊精对煤和石英浮选的影响研究

通过浮选试验、接触角测定及单矿物吸附量测量研究了糊精对浮选体系中煤和石英可浮性的影响及抑制机理。研究结果表明：在糊精用量为200g/t时,灰分为12.1%,与未添加糊精相比,精煤灰分(质量分数)降低了1.53%,浮选效果得到较大改善|接触角测定结果表明,加入糊精后,浮选精煤接触角增大,在糊精用量为300g/t时达到最大值96.26°,显著提高了煤泥可浮性|吸附量测定结果表明石英对糊精的吸附量较煤对糊精的吸附量大。糊精药剂用量增加抑制了大量精煤上浮,导致精煤灰分含量相对升高。     

会泽铅锌矿方铅矿、闪锌矿和黄铁矿的浮游性研究

本文考查了ZnSO4和可溶性淀粉对方铅矿、闪锌矿和黄铁矿浮游性的影响，为会泽铅锌矿铅硫异步等可浮工艺提供了理论依据。试验结果表明，在乙黄药浮选体系中，ZnSO4和可溶性淀粉强烈抑制闪锌矿，而对方铅矿和黄铁矿的浮游性影响不大，且两者的浮游性相近。