In situ AFM study of potassium oleate adsorption and calcium precipitate formation on an apatite surface

This study investigates the effect of ionic strength on the adsorption of potassium oleate in apatite surfaces in situ by atomic force microscopy (AFM). Natural apatite crystals were equilibrated with calcium nitrate solutions in the presence and absence of potassium oleate (4 × 10⁻³ M). AFM images for each experiment along with their histograms were recorded. The contact AFM mode allowed visualizing the topography of the surfaces with the formation of adsorbed layers and calcium dioleate colloids. The presence of calcium ions in aqueous solution (2 × 10⁻⁴ M) led to the formation of precipitated calcium carbonate/hydroxide, as evidenced in the histogram. Oleate adsorption, in the presence of high ionic strength, occurs through the formation of clusters of calcium dioleate, observed in both 2D and 3D micro-topography. The presence of these clusters makes the apatite surface heterogeneous and rough, thus influencing its flotability.     

Improving froth characteristics and flotation recovery of phosphate ores with nonionic surfactants

The beneficial effect of a series of nonylphenol polyethylene glycol ether surfactants were tested in the flotation of phosphate ores in which the mixtures of sodium oleate and dodecane were used as collectors. In order to elucidate the flotation results, equilibrium surface tension of single and binary surfactant solutions prepared with sodium oleate and nonionic surfactants were investigated. Synergism between surfactants was determined by observing the change in surface tension of solutions and by the calculation of interaction parameter from surface tension data. The lowering of surface tension of sodium oleate solutions was observed in the presence of nonionic surfactants. The interaction parameter between sodium oleate and a nonionic surfactant (i.e., NP-4) was calculated to be −0.21, showing attraction between the two surfactant molecules. The nonionic surfactant NP-4 was then tested in batch flotation of phosphate ores. The beneficial effect of nonionic surfactant was obtained at different collector dosages and surfactant combinations.     

表面活性剂对神东低阶煤润湿改性机理研究

为了探究表面活性剂对神东低阶煤的润湿改性机理,选取三种不同类型的表面活性剂,采用润湿改性试验、接触角试验、Zeta电位试验、FTIR分析和分子动力学模拟的方法,对表面活性剂的润湿改性机理进行了研究.试验结果表明:非离子型表面活性剂(曲拉通X-100)对于煤的润湿改性能力最强,其次是阴离子型表面活性剂(十二烷基苯磺酸钠)...     

钙镁离子对长石和绿帘石浮选的影响及其作用机理

通过小型浮选试验、动电位测试、吸附试验、溶液化学计算和红外光谱分析等手段研究了油酸钠体系下Ca²⁺和Mg²⁺对长石和绿帘石浮选的影响。结果表明, 纯净的长石和绿帘石矿物几乎不浮, 加入Ca²⁺、Mg²⁺后, 矿物可浮性得到改善;钙镁离子主要以Ca²⁺、CaOH⁺、CaCO₃(s)和Mg²⁺、MgOH⁺、MgCO₃(s)形式吸附在矿物表面;油酸钠和钙镁离子在长石和绿帘石矿物表面存在静电吸附, 且钙镁离子可以促进油酸钠在矿物表面的吸附。     

The role of calcium in xanthate adsorption onto sphalerite

This paper presents results of a laboratory study designed to look into the effect of calcium on sphalerite hydrophobization with xanthate making use of zeta potential, contact angle, microflotation and UV/vis spectrometry techniques. The experimental results show that xanthate adsorbs onto the mineral surface at neutral and slightly acid pH as reflected by contact angle, floatability (by microflotation) and xanthate adsorption (by UV/vis spectrometry) measurements. Apparently, xanthate adsorption is due to both the less negative surface charge of the mineral and to the presence of Zn²⁺ in equilibrium with the mineral, rather than Zn(OH)₂, which is the product of the mineral oxidation with dissolved oxygen at pH above 8. When calcium is present in the aqueous solution at concentrations similar to that of saturation for gypsum precipitation (e.g., about 0.017 mol/L), calcium apparently adsorbs on the sphalerite surface decreasing its negative charge (e.g., zeta potential) and promoting xanthate adsorption and hydrophobization, as reflected by contact angle and floatability measurements (ca. 30° and 33% recovery, respectively). Calcium adsorption appears to be favoured by the increase in pH, as reflected by the increased xanthate adsorption, thus suggesting that the calcium hydroxo-complex (CaOH⁺) is the adsorbing species. At pH 10 and 11, precipitation of calcium hydroxide (observed by SEM-EDS measurements at pH 11) appears to counteract xanthate adsorption, substantially decreasing mineral hydrophobicity. Calcium and xanthate appear to display some type of chemical interaction while calcium and dithiophosphinate do not.     

复配捕收剂改善磷矿浮选效果的机理研究

以贵州某硅钙质胶磷矿为研究对象,选取油酸钠作为磷矿正浮选的捕收剂,与几种常用的表面活性剂进行复配,考察了复配捕收剂的浮选效果,并通过表面张力、Zeta电位、红外光谱、扫描电镜和TOC测定,研究了复配捕收剂的浮选机理,确定了磷矿正浮选合适的复配捕收剂。试验结果表明,油酸钠与表面活性剂复配后用于磷矿正浮选,可以改善油酸钠在矿浆中的水溶性和分散性,降低矿浆的表面张力和磷矿的Zeta电位,提高捕收剂在磷矿表面的吸附量,促进水解的油酸根离子与磷矿表面的Ca²⁺反应生成油酸钙沉淀,从而改善磷矿正浮选效果,提高浮选指标。     

含钙矿物浮选过程中Ca-油酸胶体捕收剂的作用机理

研究了油酸钠浮选白钨矿、萤石和方解石过程中Ca-油酸[Ca(OL)₂]胶体的存在及其对浮选的影响。溶液化学计算表明,三种含钙矿物溶解的钙离子可以与油酸阴离子反应生成Ca(OL)₂胶体,并且在碱性条件下作为溶液中的主要组分存在和发挥作用。纯矿物试验结果表明,Ca(OL)₂胶体对白钨矿和萤石的捕收能力较油酸钠强,对方解石的捕收能力较油酸钠弱。Ca(OL)₂胶体吸附后的三种矿物表面疏水性差异增大,白钨矿、萤石表面疏水性强于油酸钠作用后,而方解石表面疏水性弱于油酸钠作用后。Ca(OL)₂胶体在白钨矿表面发生化学吸附,在萤石和方解石表面以化学吸附为主,当pH < 9.0时存在一定的静电吸附作用。油酸钠浮选含钙矿物过程中除油酸阴离子直接作用于矿物表面的路径外,存在另外一种重要的作用路径:钙离子与油酸阴离子在溶液中首先生成Ca(OL)₂胶体,Ca(OL)₂胶体在溶液中迁移至矿物表面发生吸附。      

油酸钠作用下红柱石和石英的浮选行为及作用机理

采用单矿物浮选试验、Zeta电位测量、红外光谱、荧光探针以及溶液化学分析, 研究了油酸钠作用下红柱石和石英的浮选行为及作用机理。结果表明, 在油酸钠作用下红柱石在pH值6～7范围内具有较好的可浮性, 石英可浮性较差;Fe³⁺能够显著提高红柱石和石英的可浮性。红柱石和石英浮选行为差异的主要原因在于红柱石表面的Al³⁺可化学吸附油酸根, 石英难以吸附油酸根离子, 因此以油酸钠作捕收剂可实现红柱石和石英的浮选分离。Fe³⁺主要以氢氧化物沉淀形式吸附于红柱石和石英表面促进油酸根在矿物表面的吸附。     

CMC浮选分离萤石与方解石作用机理研究

为了更有效地浮选分离萤石和方解石,通过浮选试验、接触角、Zeta电位、吸附量及微量热分析,研究了羧甲基纤维素（CMC）在萤石、方解石浮选分离中的作用,揭示了CMC对萤石、方解石选择性抑制机理。结果表明：CMC用量为20 mg/L时能够高效抑制方解石,当pH=8时,可最大化实现两者浮选分离。由于CMC优势组分—RCOO—大量吸附于方解石表面,使得方解石表面只能吸附较少油酸根离子,同时造成方解石Zeta电位显著负移,使其亲水增强,这与接触角测试结果一致。吸附模型表明,方解石表面Ca²⁺活性位点大量减少,难以继续吸附油酸根离子,是其被抑制的主要原因,且体系反应级数n=1。     

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.     

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.     

4种阴离子表面活性剂在煤沥青表面的润湿规律

为了探讨分散剂溶液对煤沥青表面的润湿性能,通过表面张力与接触角的测定研究了SDS,SDBS,NA和SN四种结构互异的阴离子表面活性剂溶液在煤沥青表面的润湿规律,并探讨了表面活性剂溶液在煤沥青表面的临界表面张力、铺展系数、黏附功和吸附机理。结果表明,SDS和SDBS溶液的表面张力和接触角均低于NA和SN,且计算得出的铺展系数高于NA和SN,而黏附功则低于NA和SN,说明SDS和SDBS溶液在煤沥青表面的润湿性强于NA和SN,而黏附性则低于NA和SN。4种表面活性剂的γlg-cosθ曲线均符合Zisman理论。SDS和SDBS的黏附张力(γ1gcosθ)与表面张力(γ1g)的曲线呈线性关系,可推测这两种表面活性剂分子在煤沥青表面的范德华吸附是润湿过程的主导因素。     

组合阴离子捕收剂对石英的吸附机理研究

针对铁矿石反浮选中含硅化合物浮选分离困难问题,研究组合阴离子捕收剂对石英的吸附机理,为低温浮选提供优质捕收剂。采用接触角测量仪、表面张力仪,红外光谱仪和石英微天平（QCM-D）对乙烯 枝杈型表面活性剂+油酸钠组合捕收剂在浮选过程中的作用机理进行研究。结果表明：①组合捕收剂中多杈枝表面活性剂与脂肪酸的协同效应增强石英和角闪石疏水特性,使其接触角增大,含硅化合物中角闪石比石英 更难吸附分选;②随捕收剂浓度的增加和温度的升高,组合捕收剂的表面张力逐渐减小,捕收能力增强且易生成稳定的泡沫层;③FTIR检测浸涂组合捕收剂后羧酸根的特征峰降低到1 561 cm-1和1 416 cm-1,发生明 显的红移,表明C—O键能减弱,C—O键与活化后的石英表面发生化学吸附;④QCM-D检测结果显示,组合捕收剂在石英晶体表面吸附后,能量因子改变量达到6.23×10-6。对齐大山选厂混磁精给矿在21 ℃的条件下进 行“1粗1精3扫”闭路浮选流程试验,得到精矿全铁品位68.16%,铁回收率89.93%的良好指标。     

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.     

利用铜离子改善油酸钠体系下白云母的可浮性

采用组分分布图、ζ电位、SEM-EDS和XPS等手段对白云母浮选试样进行了表征,在此基础上研究了油酸钠体系下Cu2+对白云母浮选行为的影响机理。结果表明:在矿浆pH值为12、油酸钠浓度为9.20×10-4 mol/L的条件下,当Cu2+浓度为1.18×10-4 mol/L时,其活化白云母的效果达到最佳,白云母的回收率可达到55.70%。继续增加Cu2+浓度,其活化效果减弱。Cu2+改善白云母可浮性的主要原因在于:溶液中油酸根离子与吸附在白云母表面的Cu（OH）₄2-作用,形成了疏水的油酸铜。此外,当Cu2+浓度为1.18×10-4 mol/L时,白云母表面的ζ电位达到-4.08 mV,导致白云母表面局部正电区域增加,此时Cu2+可增强油酸根等离子在白云母表面的静电吸附作用,并且Cu2+还可提高白云母表面Al和Si与油酸根等离子的反应几率,因而也会改善白云母的可浮性。Cu2+活化效果减弱的原因在于:过量的Cu2+会逐渐弱化油酸根等离子在白云母表面的静电吸附作用,并且过量的Cu2+会消耗部分捕收剂,也会降低捕收剂与矿物表面作用的概率。      

脂肪酸钠浮选盐类矿物的作用机理研究

本文通过ζ-电位测定,红外光谱分析,吸附量测定,浮选实验及溶液化学计算,研究了脂肪酸钠浮选盐类矿物的作用机理。结果表明,油酸钠在盐类矿物表面发生了化学吸附或表面反应,使盐类矿物表面负ζ-电位显著增加,油酸钠在盐类矿物表面的吸附行为与金属油酸盐生成的溶液化学条件有一致关系,磷灰石、萤石、重晶石、白钨矿、方解石浮选回收率显著上升所需捕收剂浓度,对应于表面脂肪酸钙(钡)沉淀生成所需脂肪酸钠的浓度。这表明,脂肪酸类捕收剂与盐类矿物的作用机理是表面化学反应生成金属脂肪酸盐沉淀。     

铁离子和亚铁离子对菱锌矿和石英浮选的影响

菱锌矿和石英纯矿物的浮选试验、动电位的测试、金属离子溶液化学计算结果表明,Fe3+、Fe2+对菱锌矿有明显的抑制作用;在无金属离子存在时石英基本不浮,Fe3+、Fe2+在碱性条件下能活化石英的浮选;在碱性条件下,Fe3+或Fe2+呈羟基络合物和氢氧化物吸附在石英表面,使石英表面吸附活性质点增加,是Fe3+或Fe2+活化石英浮选的主要原因;Fe3+或Fe2+生成的氢氧化物沉淀覆盖在菱锌矿表面,阻碍了捕收剂在菱锌矿表面的吸附,是Fe3+或Fe2+抑制菱锌矿浮选的主要原因。     

萤石表面钙质点的加温溶出对其浮选行为的影响

为明确加温对萤石浮选特性的影响,利用量子化学及分子动力学计算模拟研究了加温条件下萤石表面钙质点的溶出行为及加温对萤石浮选行为的影响,通过纯矿物浮选试验,钙离子溶出量、油酸根吸附量及萤石表面原子丰度的测定进一步分析了加温影响萤石浮选特性的原因。结果表明：①油酸根在萤石表面吸附的主要位点是钙质点,且吸附作用的方式是化学吸附;在常温条件下,该吸附作用稳定,吸附的油酸根不会由于萤石表面原子弛豫产生的位移轻易进入液相环境中。②温度升高会促进萤石表面钙质点的溶出,温度越高,钙质点的溶出量也越大;随着钙质点的不断溶出,在萤石表面钙质点吸附的油酸根也将出现脱附现象,因而加温对于油酸根在萤石表面的直接吸附起负效应,最终导致萤石浮选回收率下降。     

Effect of mining chemicals on biosorption of Cu(II) by the non-living biomass of the macrophyte Potamogeton lucens

The present work investigates the effect of some compounds commonly discharged from mineral processing plants on biosorption of heavy metals by the non-living biomass of the freshwater macrophyte Potamogeton lucens. Studies of sorption of Cu (II) in the presence of metal ions, surfactants, EDTA and cyanide were carried out at laboratory scale. The results show that copper adsorption by ion exchange on the biomass is not affected by equimolar concentrations of copper/sodium, copper/calcium or copper/iron. Non ionic surfactants (e.g. pine oil) do not modify biosorption, but the negative groups of anionic surfactants (e.g. sodium oleate) compete with the surface groups of the biomass for the free copper ions in solution. EDTA and cyanide react with copper ions producing soluble complexes that do not adsorb onto the biomass. The biosorption process is suitable for wastewater treatment when the heavy metal species are free in solution. Effluents containing metal sequestering compounds that produce soluble or precipitated species are not able to be treated by carboxyl groups based biosorbents.     

钙镁离子对磷矿浮选的界面反应机理探讨

磷矿资源是磷肥生产的主要原料,磷矿浮选过程中矿浆溶液含有大量的钙镁离子,钙镁离子改变矿物表面性质,导致含钙盐类矿物相互之间浮选分离的难度增加。通过矿物表面微观形貌、矿物表面接触角和捕收剂在矿物表面吸附量等分析方法,得到如下结论:钙镁离子对胶磷矿的浮选影响显著,对白云石的浮选影响微弱,钙镁离子在碱性介质中生成了碳酸盐沉淀或溶胶,粘附于胶磷矿的表面,改变了胶磷矿表面的疏水性,导致了胶磷矿的可浮性下降;但并未粘附与白云石的表面,呈自聚状态存在于矿浆中,对白云石可浮性的影响不大。