Sulphidization flotation for recovery of lead and zinc from oxide-sulfide ores

A new flowsheet was developed to recover the valuable minerals from oxide or oxide-sulfide ores of lead and zinc. The flowsheet consisted of flotation of sulfide minerals, desliming and sulphidization-flotation of oxide minerals. The corresponding reagent system and techniques to the flowsheet were investigated. Batch and continuous tests show that the dosage of sodium sulfide, temperature, and collector type are main affecting factors on the recovery of smithsonite and cerussite. For the flotation of cerussite, there is an appropriate dosage of sodium sulfide at which the recovery reaches its maximum value. The required sodium sulfide for smithsonite flotation is higher than that for cerussite and the recovery of smithsonite flotation increases with the dosage of sodium sulfide at low level and becomes insensitive at high dosage. The appropriate temperature for smithsonite and cerussite flotation is found to be 2540℃. Amines are found to be the effective collectors for the flotation of smithsonite after sulphidization. Investigation also shows that desliming prior to sulphidization-flotation is essential to the effective recovery of smithsonite and cerussite, and the desliming process of two-stage hydrocyclon is well feasible and effective for the treatment of lead-zinc oxide ores. A further treatment on the cerussite flotation concentrate by shaking table is proposed to obtain higher lead grade.

Recycle of Wastewater from Lead-Zinc Sulfide Ore Flo-tation Process by Ozone/BAC Technology

Lead-zinc sulphide ore contains lead sulphide (galena), and zinc sulphide (sphalerite). In the first flotation stage, galena is rendered hydrophobic with an organic collector such as xanthate, while sphalerite is kept from floating by depressants, and in the second flotation stage, activator was used to activated zinc flotation. Since the organic regent used are different in the two flotation stage, wastewater from the second zinc flotation stage can’t be directly recycled to the first lead flotation stage. Wastewater from flotation process for concentrating lead-zinc sulphide ore often containing organic compounds such as diethyldithiocarbamate(DDTC), xanthate, terpenic oil(2# oil) and thionocarbamate esters (Z-200), are environmentally hazardous. Their removal from contaminated water and the reuse of the water is one of the main challenges facing lead-zinc sulphide ore processing plants. In this study, synthetic wastewater containing DDTC, xanthate, 2# oil and Z-200 at concentrations ranging from 21 to 42 mg/L was fed into an Ozone/Biological activated carbon (BAC) reactor. Analyses of the effluent indicated a chemical oxygen demand (COD) removal over 86.21% and Total organic carbon (TOC) removal over 90.00% were achieved under Hydraulic retention time (HRT) of 4h and O3 feeding concentration of 33.3mg/L. The effluent was further recycled to the lab scale lead concentrating process and no significant difference was found in compare with fresh water. Furthermore, lead-zinc sulphide mineral concentrating process was carried out at lab scale. The produced wastewater was treated by Ozone/BAC reactor at O3 feeding concentration of 16.7mg/L and HRT of 4h. The effluent analysis showed that TOC removal was 74.58%. This effluent was recycled to the lab scale lead-zinc sulphide mineral concentrating process and the recovery of lead was not affected. The results showed that by using Ozone/BAC technology, the lead-zinc sulphide mineral processing wastewater could be recycled.

Sulfidation roasting of lead and zinc carbonate with sulphur by temperature gradient method

In order to enhance the lead and zinc recovery from the refractory Pb-Zn oxide ore, a new technology was developed based on sulfidation roasting with sulphur by temperature gradient method. The solid-liquid reaction system was established and the sulfidation thermodynamics of lead and zinc carbonate was calculated with the software HSC 5.0. The effects of roasting temperature,molar ratio of sulphur to lead and zinc carbonate and reaction time in the first step roasting, and holding temperature and time in the second roasting on the sulfidation extent were studied at a laboratory-scale. The experimental results show that the sulfidation extents of lead and zinc are 96.50% and 97.29% under the optimal conditions, respectively, and the artificial galena, sphalerite and wurtzite were formed. By the novel sulfidizing process, it is expected that the sulphides can be recovered by conventional flotation technology.

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%.

Reduction of lead sulfate to lead sulfide with carbon monoxide

In order to decrease the solubility of PbSO4 and enhance lead recovery from PbSO4 bearing wastes, CO was employed as a reductant to transform PbSO4 into Pb S. Reaction system was established and reductive thermodynamics of PbSO4 was calculated by software HSC 5.0. The effects of gas concentration, reaction temperature, time and mass of sample on reduction of PbSO4 were examined by thermogravimetry(TG) and XRD. Roasting tests further verify the conclusions of thermodynamic and TG analyses. The results show that increasing temperature in the reasonable range and CO content are favorable for the formation of Pb S. The reduction process is controlled by chemical reaction and calculation value of the activation energy is 47.88 k J/mol.

Interphase migration and enrichment of lead and zinc during copper slag depletion

An interphase migration and enrichment model of lead and zinc during molten copper slag depletion was established.The occurrence of various components in copper slag was predicted using sulfur-oxygen potential calculations and confirmed through high-temperature experiments.The recovery rate of copper can reach 90.13%under the optimal conditions of 1200°C,an iron to silicon mass ratio of 1.0,3 wt.%ferrous sulfide,and a duration of 45 min.Lead(54.07 wt.%)and zinc(17.42 wt.%)are found in the flue dust as lead sulfate,lead sulfide,and zinc oxide,while copper matte contains lead(14.44 wt.%)and zinc sulfide(1.29 wt.%).The remaining lead and zinc are encapsulated as oxides within the fayalite phase.

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.

Lead isotope signatures of Pb-Zn sulfide mineralization in the Reshian-Lamnian area of Azad Jammu and Kashmir,Pakistan

The Reshian-Lamnian area within the Hazara-Kashmir syntaxis in Pakistan is composed mainly of the rocks of the Salkhala,Panjal and Murree formations.Base metal sulfide mineralization in the form of sphalerite and galena with lesser amounts of chalcopyrite and pyrite is present within the Salkhala Formation of the study area.Chemically all these ore phases are homogeneous in composition.The Pb isotopic composition of galena from the area suggests that there is very little or negligible variation in the ratios of 206Pb/204Pb,207Pb/204Pb and 208Pb/204Pb.Modal ages ranging from 509 to 562 Ma and the μ values of 10.71 to 10.93 have been calculated for the studied Pb-Zn mineralization.On the basis of field features,mineralogy and Pb-isotope signatures,it is concluded that the Pb-Zn sulfide mineralization in the Reshian-Lamnia area is pre-Himalayan in age and can be correlated with the Cambro-Ordovician(Pan-African) orogenic event.

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.

Recovery of Lead from Sulfide Concentrate after Mechanochemical Activation Using Nitric Acid

Decomposition of lead sulfide concentrates in nitric acidic solutions after ferric(Ⅲ)nitrate addition and mechanical preparation has been investigated.It was found out that the decomposition can be achieved in HNO_(3) solution(>1.5 mol·L^(-1))at the temperature above 85℃.The leaching rate of lead can be increased by means of mechanochemical activation.The use of[Fe(NO_(3))_(3)-HNO_(3)-H_(2)O]aqueous salt system allows the decomposition of lead sulfide concentrate at room temperature and in this case the concentration of HNO_(3) does not exceed 0.05-0.1 mol.L^(-1),The degree of lead recovery into solution from PbS concentrate reaches 99.3%-99.6c70 with the mechanochemical activation of this concentrate.The insoluble residues after the leaching contain SiO_(2),S^(0),FeCO_(3) and PbSO_(4).

Analysis of Oxygen Consumption in Lead and Zinc Metallurgy

This article analyzes the role of oxygen in lead zinc metallurgy,including shortening the metallurgical process,promoting energy conservation and environmental protection,improving metallurgical strength,enhancing raw material adaptability,and enhancing comprehensive recovery efficiency.This article introduces different lead zinc metallurgical processes and their oxygen consumption characteristics,including oxygen enriched side blowing lead smelting,oxygen bottom blowing lead smelting,oxygen enriched top blowing lead smelting,flash smelting lead,oxygen pressure leaching zinc smelting,and atmospheric pressure oxygen leaching zinc smelting.It is pointed out that oxygen enhanced metallurgy is the direction for the transformation and upgrading of lead zinc metallurgy.

Nanostructured Lead Sulfide Containing Nanoholes Templated by Lyotropic Hexagonal Liquid Crystals

The hexagonal liquid crystal mediated synthesis of nanostructured PbS was studied. Thioacetamide and lead acetate were used as the sulfide and lead source, respectively. It was found that the nanohole structure of PdS was formed in this system.

Determination of Sulfides in FCC Gasoline by Using the Potentiometric Titration of Lead Tetraacetate

Compared with conventional method of violet spectrum, determination of the content of sulfides in fluid catalytic cracking (FCC) gasoline by using the potentiometric titration of lead tetraacetate has some advantages such as clear potentiometric abrupt change at the stoichiometric point, stable potentiometric value, exact and credible results, and simple operation. The content of sulfides in FCC gasoline of Shenghua refinery is 0.136% by this method. The standard deviation about this method is less than 0.01% and the relative standard deviation is less than 2.42%.

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.

Estimation of lead and zinc emissions from mineral exploitation based on characteristics of lead/zinc deposits in China

Nonferrous mining activities are some of the largest sources of heavy metals emissions into the environment and China is one of the largest producers and consumers of lead and zinc in the world.The cumulative productions and emissions of lead and zinc from mining-related activities in China were estimated.Up to 2007,the cumulative productions of lead and zinc in China were estimated to be about 6.69 and 12.59 Mt,respectively;and about 1.62 Mt lead and 3.32 Mt zinc emitted into the ambient environment during the mining,processing and smelting activities,representing 24.39% and 26.36% cumulative production,respectively.Among these three types of mining-related activities,mineral processing contributes the most to the total emission of 50.67% lead and 45.51% zinc.

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.

Selective recovery of lead from zinc oxide dust with alkaline Na_2EDTA solution

The selective recovery of lead from the zinc oxide dust using an alkaline Na2EDTA solution was investigated. The effects of temperature, leaching time, Na2EDTA concentration and initial NaOH concentration on the leaching rates of lead and zinc were studied. The following optimized leaching conditions were obtained： liquid-to-solid ratio 5：1 mL/g, stirring speed 650 r/min, Na2EDTA concentration 0.12 mol/L, initial NaOH concentration 0.5 mol/L, leaching temperature 70 ℃, leaching time 120 min. Under the optimized conditions, the average leaching rates of lead, zinc, fluoride and chloride are 89.92%, 0.94%, 62.84% and 90.02%, respectively. The filtrate was used to electrowin lead powders. The average current efficiency of electrowinning is about 93% and lead content is higher than 98% under the conditions of temperature of 60 ℃, current density of 200 A/m2, H3PO4 concentration of 1.5 g/L, and lead ion concentration of above 5 g/L. The consumption of Na2EDTA and the direct current are about respectively 0.218 kg and 0.958 kW·h for per kilogram of lead powder.

Effects of field application of phosphate fertilizers on the availability and uptake of lead, zinc and cadmium by cabbage (Brassica chinensis L.) in a mining tailing contaminated soil

A field trial was conducted to evaluate the reduction of bioavailability of heavy metals including lead (Pb), zinc (Zn) and cadmium (Cd) in a soil contaminated by mining tailings in Shaoxing, Zhejiang, China. Three commercial phosphate (P) fertilizers including phosphate rock (PR), calcium magnesium phosphate (CMP), and single superphosphate (SSP) were applied to the plot at three P application rates, 50, 300, and 500 g/m2 with 9 treatments and control (CK). Plants, water soluble and exchangeable (WE) extra...