Pressure acid leaching of zinc sulfide concentrate

Effects of particle size of the zinc sulfide concentrate,leaching temperature,solid-to-liquid ratio and additive amount on pressure acid leaching process of the zinc sulfide concentrate were studied.The results indicate that the additive can improve the reaction kinetics and the conversion rate.And sulfur can be successfully separated from the zinc sulfide concentrate as elemental sulfur.The reasonable experiment parameters are obtained as follows:the leaching temperature 150℃,oxygen partial pressure 1 MPa,additive amount 1%,solid-to-liquid ratio 1:4,leaching time 2 h,initial sulfuric acid concentration 15%,and particle size less than 44μm.Under the optimum conditions,the leaching rate of the zinc can reach 95%and the reduction rate of the sulfur can reach 90%.

E-pH diagram of ZnS-H_2O system during high pressure leaching of zinc sulfide

The values of GΘ,EΘ or pH from 110 to 160℃ were calculated and the relevant potential expressions were obtained.E-pH diagrams of ZnS-H2O system at oxygen partial pressure of 0.8 MPa,ionic activity of 1.0 and different temperatures were drawn through thermodynamical calculation.With the temperature increasing,the stable regions of S and Zn(Ⅱ) in the E-pH diagrams become gradually larger,but the amplification decreases over 150℃.The impacts of leaching parameters,such as temperature,liquid to solid ratio,initial acidic concentration,leaching time,oxygen partial pressure and stirring speed on the leaching rate of Zn(Ⅱ) and conversion rate of S in the single factor of high pressure leaching experiment of ZnS in autoclave,were studied.The leaching residue was examined by X-ray fluorescence(XRF) chemical composition identification and X-ray diffraction(XRD) phase identification,and the content of the leaching solution was tested by inductively coupled plasma-atomic emission spectrometry(ICP).The experimental results indicate that the leaching rate of zinc increases from 60.05% to 97.85% and the conversion rate of sulfur increases from 38.90% to 80.92% with the temperature increasing from 110℃ to 150℃,5:1 of liquid-to-solid ratio,150 g/L of initial acidic concentration,120 min of leaching time,0.8 MPa of oxygen partial pressure,and 480 r/min of stirring speed,which tend to be stable over 150℃.The experimental results correspond with theoretical calculation.

A review of major non-sulfide zinc deposits in Iran

The numerous non-sulfide zinc ore deposits were the historical basis for the development of zinc mining in Iran.They include the Mehdiabad,Irankouh and Angouran world-class deposits,as well as the Zarigan and Haft-har deposits.These deposits were formed by supergene oxidation of primary sulfide minerals during the complex interplay of tectonic uplift,karst development,changes in the level of the water table,and weathering.Zn(Pb)carbonates,Zn-hydrosilicates and associated hydrated phases directly replace the primary ore bodies or fill cavities along fractures related to uplift tectonics.Direct replacement of primary sulfides is accompanied by distal precipitation of zinc non-sulfide minerals in cavities or internal sediments filling.The mineralogy of the non-sulfide mineralization in all six deposits is generally complex and consists of smithsonite,hydrozincite,and hemimorphite as the main economic minerals,accompanied by iron and manganese oxy-hydroxides and residual clays.Commonly,non-sulfide minerals in these deposits consist of two types of ore:red zinc ore(RZO),rich in Zn,Fe,Pb-(As)and white zinc ore(WZO),typically with very high zinc grades but low concentrations of iron and lead.Typical minerals of the RZO are Fe-oxyhydroxides,goethite,hematite,hemimorphite,smithsonite and/or hydrozincite and cerussite.Common minerals of the WZO are smithsonite or hydrozincite and only minor amounts of Fe-oxyhydroxides and hemimorphite.

Effect of ammonium sulfate on the formation of zinc sulfide species on hemimorphite surface and its role in sulfidation flotation

Effectively strengthening the surface sulfidation is essential for recovering hemimorphite by froth flotation.In this work,inductively coupled plasma optical emission spectrometer(ICP-OES)measurements,Visual MINTEQ calculation,X-ray photoelectron spectroscopy(XPS)analysis,time of flight secondary ion mass spectrometry(ToF-SIMS)analysis,and micro-flotation experiments were explored to systematically investigate the effect of ammonium sulfate((NH_(4))_(2)SO_(4))on the formation of zinc sulfide species on hemimorphite surface and its role in sulfidation flotation.The results showed that(NH_(4))_(2)SO_(4)exhibited a positive influence on hemimorphite sulfidation flotation.It was ascribed to the number of zinc components in the form of Zn^(2+)and[Zn(NH_(3))_(i)]^(2+)(i=1–4)increased in the flotation system after hemimorphite treatment with(NH_(4))_(2)SO_(4),which was beneficial to its interaction with sulfur species in solution,resulting in a dense and stable zinc sulfide layer generated on the hemimorphite surface.[Zn(NH_(3))_(i)]^(2+)participated in the sulfidation reaction of hemimorphite as a transition state.In addition the sulfidation reaction of hemimorphite was accelerated by(NH_(4))_(2)SO_(4).Thus,(NH_(4))_(2)SO_(4)presents a vital role in promoting the sulfidation of hemimorphite.

Nucleation and Growth of Zinc Sulfide Nanoparticles in Ultrathin Polymer Films by Layer-by-Layer Polyionic Assemblies

In this work, zinc sulfide (ZnS) nanoparticles were formed by nucleation and growth in ultrathin films of polydiallyldi-methylammonium chloride (PDDA)–polystyrenesulfonate sodium salt (PSS) film produced by the Layer-by-Layer (LbL) deposition technique. Multilayer thin film assemblies, fabricated by sequential adsorption of polyelectrolytes on a quartz substrate, were used as a supramolecular reaction template to study the in-situ nucleation and growth of ZnS nanoparticles. ZnS nanoparticles were nucleated within the polymeric supramolecular structure through cyclic expo-sure to the solutions of Zn(NO3)2 and thiourea. The growth and nucleation of nanoparticles were accomplished by a cyclic repetition of reductive hydrolysis reactions. The growth of a thin film on a flat substrate via LbL was monitored by ultraviolet-visible (UV-Vis) spectroscopy. Analysis of the UV-visible absorption spectra of the films revealed that the nanoparticles grew with increasing number of cycles. The presence of ZnS nanoparticles were verified by transmission electron microscopy (TEM). Selected area electron diffraction (SAED) showed that the ZnS has a cubic spheralite structure.

Structural and Characteristics of Manganese Doped Zinc Sulfide Nanoparticles and Its Antibacterial Effect against Gram-Positive and Gram-Negative Bacteria

The Manganese doped zinc sulfide nanoparticles of the cubic zinc blende structure with the average crystallite size of about 3.56 nm were synthesized using a coprecipitation method using Thioglycolic Acid as an external capping agent for surface modification. The ZnS:Mn2+ nanoparticles of diameter 3.56 nm were manufactured through using inexpensive precursors in an efficient and eco-friendly way. X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Fourier Transform Infrared (FTIR) spectroscopy are used to examine the structure, morphology and chemical composition of the nanoparticles. The antimicrobial activity of (ZnS:Mn2+) nanocrystals was investigated by measuring the diameter of inhibition zone using well diffusion mechanism versus two various bacterial strains. The technique of microorganism inactivation was considered as sorts-dependent. Bacillus subtilis showed the largest antibacterial sensitivity (35 mm) to ZnS: Mn2+ nanoparticles at a concentration (50 mM) whereas Escherichia coli offered maximum zone of inhibition (20 mm) at the same concentration. In this study, the results indicated that ZnS:Mn2+ nanoparticles were found to have significant antibacterial activity against Gram-negative (E. coli) and Gram-positive (Bacillus subtilis) bacteria.

Mechano-chemical sulfidization of zinc oxide by grinding with sulfur and reductive additives

A novel process for sulfidation of ZnO by co-grinding with sulfur and reductive additives （P, Fe, A1, and Mg） was developed. The sulfidation extent of ZnO with the addition of P, Fe, A1 or Mg can reach 85.2%, 81.6%, 96.7% and 92.6% after grinding for 4, 6, 1 and 1 h, respectively. Based on the chemical phase composition analysis and morphological characteristics of sulfidized products by XRD, SEM and TEM, a possible reaction mechanism, mechanically induced self-propagating reaction （MSR）, was proposed to explain the sulfidization reaction. In addition, the floatability of sulfidized products was investigated for the recovery of metal sulfide and ZnS can be concentrated with a high concentration ratio and concentrate grade. By using the sulfidizing process, it is expected that the recovery of zinc from the wastes or purification of heavy-metal-containing hazardous residues is technically feasible.

Sulfidation roasting of zinc leaching residue with pyrite for recovery of zinc and iron

Zinc leaching residue(ZLR) contains high content of valuable metals such as zinc and iron. However, zinc and iron mainly exist in the form of zinc ferrite, which are difficult to separate and recover. This study proposed a new process involving sulfidation roasting, magnetic separation and flotation to recover zinc and iron in ZLR. Through sulfidation roasting of ZLR with pyrite, zinc and iron were converted into ZnS and Fe3 O4. The effects of pyrite dosage, roasting temperature and roasting time on the sulfidation of zinc in ZLR were investigated. The results showed that the sulfidation percentage of zinc reached 91.8% under the optimum condition. Besides, it was found that ball-milling was favorable for the separation and recovery of zinc and iron in sulfidation products. After ball-milling pretreatment, iron and zinc were enriched from sulfidation products by magnetic separation and flotation. The grade of iron in magnetic concentrates was 52.3% and the grade of zinc in flotation concentrates was 31.7%, which realized the recovery of resources.

Reaction behaviors of Pb and Zn sulfates during reduction roasting of Zn leaching residue and flotation of artificial sulfide minerals

To evaluate the feasibility of recovering Pb and Zn sulfides and Ag-containing minerals from Zn leaching residue by the process of reduction roasting followed by flotation,the reaction behaviors of Pb and Zn sulfates during this process were investigated.Chemical analysis showed that the transformation ratios of PbSO4 and ZnSO4 could reach 65.51%and 52.12%,respectively,after reduction roasting,and the introduction of a sulfidation agent could improve the transformation ratios of these sulfates.scanning electron microscopy-energy dispersive spectroscopy(SEM-EDS)revealed that temperature obviously affects the particle size,crystal growth,and morphology of the artificial Pb and Zn sulfide minerals.Particle size analysis demonstrated that the particle size of the materials increases after roasting.Flotation tests revealed that a flotation concentrate composed of 12.01wt%Pb,27.78wt%Zn,and 6.975×10^(−2)wt%Ag with recoveries of 60.54%,29.24%,and 57.64%,respectively,could be obtained after roasting.

Highly uniform Co-Cu bimetallic sulfides for rechargeable alkaline aqueous zinc batteries

Rechargeable alkaline aqueous zinc batteries(RAZBs)have attracted increasing attention.However,most RAZBs are hindered by the limited availability of cathode materials.The practical electrochemical performance of most cathode materials is lower than the theoretical value due to their poor electrical conductivity and low utilization capacity.In this work,we develop a facile hydrothermal procedure to prepare highly uniform bimetallic sulfides as novel cathode materials for RAZBs.Copper-cobalt binary metallic oxides materials possess higher conductivity and larger capacity compared with their mono-metal oxides compounds due to bimetallic synergistic effects and multiple oxidation states.Furthermore,bimetallic sulfide compounds have smaller bond energy and longer bond length than their oxides,leading to less structural damage,faster kinetics of electrochemical reactions,and better stability.The as-prepared Co-Cu bimetallic sulfides show enhanced electrochemical performance due to various valences of Co and Cu as well as the existence of S.As a result,aqueous Zn/CuCo_(2)S_(4) battery shows a high specific capacity of 117.4 mAh/g at 4 A/g and a good cycle life of over 8000 cycles.Based on PANa hydrogel electrolytes,a flexible Zn/CuCo_(2)S_(4) battery demonstrates excellent cycling stability.This battery can also meet the requirements of electronic devices with different shapes and performs well in extreme environments,such as freezing,drilling,and hammering.This work opens new avenues to obtain high-rate and long-life cathode materials for RAZBs by utilizing the synergistic effects of bimetallic sulfides and provides a new platform for flexible energy storage devices.

Bench-Scale Testing of Zinc Ferrite Sorbent for Hot Gas Clean-up

Advanced integrated gasification combined cycle （IGCC） power generation systems require the development of high-temperature, regenerable desulfurization sorbents, which are capable of removing hydrogen sulfide from coal gasifier gas to very low levels. In this paper, zinc ferrites prepared by co-precipitation were identified as a novel coal gas desulfurization sorbent at high temperature. Preparation of zinc ferrite and effects of binders on pore volume, strength and desulfurization efficiency of zinc ferrite desulfurizer were studied. Moreover, the behavior of zinc ferrite sorbent during desulfurization and regeneration under the temperature range of 350-400 ℃ are investigated. Effects of binders on the pore volume, mechanical strength and desulfurization efficiency of zinc ferrite sorbents indicated that the addition of kaolinite to zinc ferrite desulfurizer seems to be superior to other binders under the experimental conditions.

硫化锌精矿氧压浸出过程中硫回收率的影响机制

锌氧压浸出特点是硫化锌精矿直接湿法浸出,硫不进入烟气,而是直接转化成单质硫回收。该工艺生产流程更简单,环境友好,综合能耗低,硫磺产品相对更容易储存、运输及销售。因此该技术的推广应用对锌冶炼行业节能减排乃至碳达峰碳中和目标的实现意义重大。从精矿矿物特征及金属的浸出率、浸出过程中硫元素的酸化率、硫磺结晶过程控制、硫浮选效率以及硫精矿热过滤温度等方面着手,研究其对硫磺回收率的影响机制。

Al掺杂硫铟锌光催化剂的制备综合实验教学设计与实践

结合化学工程与工艺专业人才培养方案和实践教学体系的要求,设计了硫铟锌(ZnIn2S4)基光催化剂的制备综合性实验。实验采用溶剂热法制备了Al掺杂硫铟锌光催化剂,系统地表征分析了光催化剂的晶体结构、形貌以及光电化学特性。该实验是将典型的科研成果转化为实验教学内容,有助于学生了解该领域的前沿科学成果和研究方法,掌握光催化剂的制备技术,进而深入理解光电化学性能相关专业理论知识。科研反哺教学有利于创新实验教学内容,激发和培养学生的创新意识和专业综合实践能力。

硫化钠体系中异极矿表面的硫化特性及硫化产物解析

通过多种分析检测方法揭示硫化钠体系中异极矿表面的硫化特性和机理,并对异极矿表面硫化产物进行分析测试。研究结果表明,硫化钠浓度对异极矿表面的硫化效果具有显著影响,即提高硫化钠浓度能促进矿浆溶液中硫组分与矿物表面反应,从而提高异极矿表面硫化产物的含量及矿物表面的疏水性。XPS和ToF-SIMS分析表明,异极矿表面的硫化产物并非单一的硫化物,而是由硫化物(S^(2−))和多硫化物(S_(n)^(2−))组成,且矿物表面多硫化物含量随硫化钠浓度的增加而增加,从而增强异极矿表面硫化产物的活性。

锌冶炼副产物制备硫化锌吸附剂脱除气态汞的研究

基于以废治废的理念,以锌冶炼过程中产生的高硫渣和次氧化锌为原料,通过高温硫化的方式制备金属硫化锌吸附剂,采用X射线衍射(XRD)、拉曼光谱(Raman)、扫描电子显微镜(SEM)和比表面积分析(BET)等方法对不同焙烧温度和焙烧时间下制备的硫化锌吸附剂进行表征分析,并考察不同烟气温度和烟气成分对吸附剂脱汞性能的影响.实验结果表明:在焙烧温度和保温时间分别达到250℃和60 min后可实现硫化锌吸附剂的成功制备,且表面形成大量的介孔孔洞;制备的ZnS-250℃-90 min具有最佳的吸附性能,在烟气温度150℃以内,对气态单质汞(Hg^(0))的平均吸附效率在99%以上,且对烟气中的O_(2)、SO_(2)和H_(2)O具有较高的抗性;在模拟锌冶炼烟气成分和半穿透条件下,ZnS-250℃-90 min对Hg^(0)的吸附容量可达3.04 mg·g^(-1),优于常规金属硫化物吸附剂;硫化锌吸附剂表面的不饱和短链硫(Sx2-)为Hg^(0)的关键活性位点,其可与烟气中的Hg^(0)反应化学吸附反应,形成稳定的HgS,从而实现烟气中Hg^(0)的净化;采用热脱附和多硫化物浸渍可实现吸附剂的循环再生,五次循环后吸附剂对Hg^(0)的吸附效率保持在98%以上,汞以单质汞的形式得到回收.本研究不仅为锌冶炼行低成本汞污染控制和汞资源化利用提供了基础,也为锌冶炼废弃物再利用提供支撑,促进锌冶炼行业的绿色生产.

贵州某硫化铅锌矿选矿试验研究

贵州某硫化铅锌矿的矿物共生关系复杂,嵌布粒度大小不均匀。为实现矿石中有价金属铅和锌的高效利用,采用优先浮选工艺,并采用新型高效环保锌活化剂X-43替代硫酸铜,通过铅锌浮选条件试验确定适宜的选矿工艺流程和药剂制度。试验结果表明,对于铅品位4.23%、锌品位8.02%的原矿,在磨矿细度为-0.074 mm占80%的条件下,优先选铅时采用1次粗选、1次扫选和铅粗精矿再磨至-0.045 mm占65.5%后3次精选,可获得铅品位50.19%、回收率65.33%的铅精矿;选铅尾矿经活化剂X-43活化后,采用1次粗选、2次扫选和2次精选选锌;经全流程闭路试验可得到铅品位为57.63%、回收率为80.50%的铅精矿,以及锌品位为49.62%、回收率为92.52%的锌精矿,尽可能地实现了铅和锌的有效回收。研究结果可为新型高效锌活化剂X-43的应用和同类型铅锌矿石开发利用提供借鉴。

矿浆难免离子对铅锌硫化矿分离的影响研究进展

这是一篇矿物加工工程领域的论文。矿浆溶液中普遍存在一些难免离子,并且其中存在的难免离子对铅锌硫化矿的浮选分离有着重要影响。矿浆中难免离子主要来源于选厂用水、矿物自身溶解、活化剂或者抑制剂解离以及流体包裹体释放引入的原生离子和磨矿过程中引入的次生离子。本文对矿浆中引入的原生离子以及磨矿体系引入的次生难免离子对铅锌硫化矿浮选分离的影响进行了总结分析发现,不论是原生离子还是次生离子对铅锌硫化矿浮选行为的影响均较为明显,较多的学者针对这种现象进行了大量的研究。通过药剂调控以及改变磨矿环境等方法已经取得了较大的突破,为后续研究者提供了重要的研究思路。本文的关注点是将前人的研究成果与现场工艺紧密结合,在不影响工业经济情况下如何从源头消除难免离子,如何从现场工艺中降低难免离子对浮选指标的影响仍是未来研究的重要方向。

CuS/ZnS纳米复合材料的制备及其作为润滑油添加剂的摩擦学行为研究

采用水热法制备了CuS/ZnS纳米复合材料,利用XRD、SEM等仪器对其结构进行了表征。结果表明:所制备的CuS/ZnS纳米复合材料呈微球结构,具有较细的颗粒尺寸和良好的分散性。采用四球摩擦试验机考察了所制样品作为添加剂在基础油中的摩擦性能,利用SEM和光学显微镜观察了摩擦钢球表面磨痕形貌和磨斑直径大小,同时使用EDS对钢球表面典型元素进行测试,分析纳米材料对基础油摩擦学性能的影响机理。结果表明,加人CuS/ZnS的混合润滑油比基础油的摩擦系数和磨斑大小分别降低了30%和22%,表现出良好的减摩抗磨性能。EDS的结果表明,所制备的纳米复合材料在钢球表面形成了一层润滑膜,减少了摩擦副之间的直接接触。

氰化尾渣综合回收利用工艺优化研究

鉴于国家环保政策的调整,环保部等三部委已将“采用氰化物进行选矿过程中产生的氰化尾渣”定为危险废物,而即将执行的新环保税法将对危险废物征收1000元/t的环境保护税,氰化废物的经济消解是未来氰化厂主要研究课题和发展方向。山东某氰化尾渣中含有一定品位的铅、锌、铜,该氰化尾渣不进行回收处理,不仅会造成资源浪费,也会对环境造成污染。如果对这部分多金属进行回收,会产生良好的经济效益。从氰化尾渣中回收有价金属元素不同于从原矿中回收有价金属元素,回收其中的有价元素较困难。为解决此问题,根据该氰化尾渣的性质,采取代表性的尾渣矿样,拟采取确定合理的选矿工艺回收尾矿中的有价金属,采用先浮铅锌再浮硫的优先浮选工艺流程试验,该试验流程能够取得较好的有价金属元素回收效果。结果表明,在原矿含铅2.56%、含锌0.95%、含铜0.19%的条件下,采用一粗两精两扫的流程浮选铅锌、一粗两精两扫的流程浮选硫的工艺,处理该氰化尾渣,获得了含铅品位19.77%、回收率21.50%,锌品位19.69%、回收率71.07%,铜含量1.43%的铅锌精矿,硫品位45.27%、回收率35.92%的硫精矿。新工艺流程指标更优,药剂成本更低、工艺更简洁,不仅铅锌精矿中铅、锌均得到有效的回收,其中伴生硫的指标也得到了改善,为氰化尾渣中铅锌铜硫的回收提供了方案。

Ni/Fe/Co助剂对ZnO/MCM-41高温煤气脱硫过程中放硫的抑制作用及改性脱硫剂再生行为

高温煤气脱硫是煤炭清洁高效利用的关键步骤之一。前期研究发现,MCM-41负载ZnO高温煤气脱硫剂(ZnO/MCM-41)脱硫性能优良,但其脱硫过程中存在生成COS的放硫现象;尽管提出了引入助剂调变上述放硫行为的策略,但缺乏助剂与脱硫剂匹配特性及改性脱硫剂再生行为的研究。本研究表明,在ZnO/MCM-41中引入质量分数1%~5%助剂(Ni/Fe/Co),均可有效抑制COS释放(释放量分别降低99.4%~99.9%、73.1%~93.4%和69.0%~98.4%),这主要归因于助剂对COS氢解的催化作用;脱硫剂中镍、铁分别以Ni^(2+)和Fe^(3+)形式存在,而钴以Co^(2+)和Co^(3+)形式共存;对于性能最优的Ni掺杂(质量分数3%)脱硫剂,其再生温度应不低于600℃(低温再生仍存在部分ZnS);且脱硫剂经四次循环再生实验后可维持高硫容(初次的91.5%)及低COS释放量(4.8×10^(-2)g羰基硫/100g脱硫剂),轻微的性能下降可归因于活性组分及助剂的少部分损失。上述研究可为高性能脱硫剂构筑提供理论指导。