DFT research on activation of sphalerite

Activation of sphalerite ZnS, (Zn, Fe)S, (Zn, Cu)S were carried out using the density functional theory (DFT) method. The electronic structures and related properties of three kind of zinc sulfide compounds were investigated. In addition, the relation between electronic structure and flotation behavior was discussed. The results show that, ZnS has a broader band gap than (Zn,Cu)S and (Zn,Fe)S do, and it has low electrochemistry activity to react with flotation collectors to render the surface hydrophobic. When the Zn atom in ZnS is replaced by Cu atom,the band gap will be reduced, and the top valence band will be occupied by Cu 3d orbit, thus it is beneficial to the interaction between mineral surface and collector.     

闪锌矿(110)表面离子吸附的动力学模拟

为了查清高碱电位环境对闪锌矿表面性质抑制作用的根本原因 ,采用C2 Soterware分子力场中的万能力场方法 ,对闪锌矿 (110 )表面CaOH 和OH-两种离子的吸附进行了动力学模拟 ,并对吸附能和吸附质量云图进行了分析。模拟结果表明 ,相对于OH-来说 ,CaOH 在闪锌矿 (110 )表面的吸附能更负 ,吸附量更大。由此可知 ,这些吸附在表面的离子又与OH-和硫化矿氧化产物产生的SO2 -4等离子作用形成不溶性亲水表面产物 ,从而导致矿物受到抑制 ,这也正是高碱电位调控成功的原因之一。     

Physical chemistry mechanisms of CDR system in sulphide mineral flotation

The flotation tests,zeta potential measurements,and Fourier transform infrared spectroscopy(FTIR) analysis on galena,sphalerite,and pyrite were studied in a collecting-depressing-reactivating(CDR) system.In this system,sulphide minerals were first collected and acti-vated by the collector,and then depressed strongly by Ca(OH)2 in a strong alkaline solution.Finally,they were reactivated by H2SO4.The flotation tests of pure minerals showed that in the Ca(OH)2 depressing process sulphide minerals had similar flotation characteristics because they had already been influenced by the collector.Hence,the flotability differences between them were reduced.However,in the H2SO4 re-activating process considerable differences in the flotability between galena and sphalerite/pyrite were produced.That is to say,galena was relatively easy to be reactivated by H2SO4,but sphalerite and pyrite were not reactivated at pH 11.The zeta potentials of sulfide minerals measured by the Zeta Plus presented irreversible characteristics on the change of pH values.The results of the FTIR spectra analysis indi-cated that the collectors already adsorbed on the mineral surface were removed partially by Ca(OH)2.     

高铁闪锌矿高压酸浸过程中ZnS-FeS-H2O系的电位-pH图

对高铁闪锌矿高压酸浸的热力学过程进行了研究,并绘制了150℃、氧气压力为1 MPa时,浸出体系中ZnS-H2O系、FeS-H2O系、ZnS-FeS-H2O系的电位-pH图。     

Impact of gypsum supersaturated process water on the interactions between silica and zinc sulphide minerals

Flotation recovery and selectivity problems have been reported in the flotation of fine sulphide minerals in gypsum supersaturated process water. In this study, the effect of gypsum supersaturated solution on the interactions between silica and sphalerite (ZnS) minerals was examined by observing deposition behaviour of silica nanoparticles on sphalerite surface using a quartz crystal microbalance with dissipation (QCM-D). Significant deposition of silica nanoparticles on ZnS coated sensor surface was observed in the gypsum supersaturated solution, indicating consequential slime coating of silica fines on sphalerite mineral surface. Substantial deposition of silica nanoparticles on SiO₂ coated surface was also observed suggesting strong homo-aggregation of silica fines in the gypsum supersaturated solution. The interaction behaviour between silica–sphalerite and silica–silica is mainly attributed to the high calcium concentration of the gypsum supersaturated solution. Similar deposition behaviour of silica nanoparticles onto ZnS or SiO₂ coated sensor surface was observed in 800 ppm calcium solution, which is similar to the calcium concentration of the gypsum supersaturated solution. Colloidal force measurement between a silica particle and a fractured sphalerite surface or a silica wafer surface by an atomic force microscopy (AFM) revealed attractive van der Waals force between the mineral particles in both gypsum supersaturated solution and 800 ppm calcium solution. The high calcium concentration of the gypsum supersaturated solution induced the hetero-aggregation between silica and sphalerite, accounting for the observed decrease in flotation selectivity.     

Selective recovery of valuable metals from partial silicated sphalerite at elevated temperature with sulfuric acid solution

The purpose of this work was to study the feasibility at laboratory-scale of a hydrometallurgical process for the selective recovery of valuable metals from partial silicated sphalerite in an oxygen pressure acid leaching system. The factors influencing dissolution efficiency of the ore were investigated and optimized. Under optimum conditions (i.e., temperature of 433 K, sulfuric acid concentration of 41.2 g/L, leaching time of 2.5 h, liquid/solid ratio of 6 mL/g, and pressure of 1.6 MPa) over 97% Zn was extracted into the leach liquor together with 0.3% SiO₂ and 2.9% Pb. The leaching slurry had good solid–liquid separation characteristics, and the filtration rate could be as high as 716 L/m² h. About 96% oxidation of sulfide sulfur to sulfate was achieved under these conditions. Analysis of the content of elemental sulfur in the leaching residues indicated that the fraction of sulfide sulfur determined as elemental sulfur was about 10% at 393 K, and that it decreased with temperature down to 0.5% at 453 K. Ultimate solid residues, which have been concentrated in silica and lead, can be oriented toward the lead smelter after alkali roasting-water washing pretreatment for metal recovery.     

Influence of high concentration Zn2+ on floatability of sphalerite in acidic system

The influence of high concentration Zn²⁺ on the floatability of sphalerite in an acidic system was investigated via flotation experiments, zeta potential measurements, contact angle measurements, and X-ray photoelectron spectroscopy. The results indicated that Zn²⁺ was adsorbed on the sphalerite surface and a Zn-hydroxyl complex was formed at a pH of 4 and a Zn²⁺ concentration of 4×10⁻² mol/L. The zeta potential increased and the contact angle decreased from 84.80° to 36.48°, strongly inhibiting the floatability of sphalerite. When S²⁻ or Cu²⁺ activator was used alone, sphalerite was not activated after Zn²⁺ was adsorbed, and its contact angle did not change significantly. However, by using a combination of S²⁻ and Cu²⁺ activators, its floatability was realized after Zn²⁺ adsorption. This result was attributed to the removal of the Zn-hydroxyl complex on the surface of sphalerite by S²⁻. After this removal, Cu²⁺ was adsorbed on the sphalerite surface to form a Cu₂S·S⁰ hydrophobic film.     

国外某复杂低品位铅锌矿选矿工艺优化及应用

某铅锌矿原矿铅含量为1.26%,含锌6.53%,含硫30.38%。生产上采用“铅锌依次优先浮选-中矿顺序返回”工艺流程,生产指标为铅精矿铅品位50.69%,含锌12.61%,铅回收率75.53%,锌精矿锌品位48.77%,含铅1.59%,锌回收率73.91%。铅锌互含较高,锌精矿指标不理想。为了解决该问题,本文在了解现场生产工艺流程及矿石性质的基础上,针对该铅锌矿开展了详细的选矿工艺优化试验,通过对部分药剂制度进行优化,采用特效捕收剂BK-LY11,同时在锌浮选回路采用中矿再磨工艺,显著改善了铅锌互含情况,有效提高了铅锌选别指标,并成功应用于生产实践,优化后获得的铅、锌回收率分别提高了5.83、8.46个百分点。     

江西银山铜铅锌多金属矿床闪锌矿的标型特征

该矿床闪锌矿分３个世代产出，从早到晚其含量铁量降低，颜色变浅，晶胞梭长ａ０增大，显微硬度降低．闪锌矿微量元素具有低Ｍｎ，Ｃｄ，高Ｇａ，Ｚｎ的火山一次火山热液矿床的成因特征．从早到晚，闪锌矿的Ｃｕ，Ｍｎ，Ｉｎ，Ｇａ，Ａｕ逐渐降低，Ａｇ，Ｈｇ，Ｃｄ逐渐升高，闪锌矿的Ａｇ、Ｃｕ含量高时可作为矿床Ａｇ、Ｃｕ矿化的标志．闪锌矿的稀土元素特征与火山一次火山岩相一致，，无明显铕异常．硫同位素δ（３４）Ｓ‰均值为２．３１，离差小，闪锌矿包裹体成分阳离子为Ｎａ＋－Ｋ－Ｃａ（２＋）＋Ｍｇ（２＋）型，指示矿床成矿的物质来源与火山作用有关     

湿法制备超细锰锌铁氧体前驱粉工艺条件研究

以软锰矿、闪锌矿、硫铁矿为原料 ,经酸浸取对浸出液进行除杂、精制 ,采用碳铵共沉淀法制取锰锌铁氧体微粉 ,对工艺条件进行了研究。该工艺具有生产成本低 ,产品回收率高 ,节省能源等优点。