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.

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.

Alkaline leaching of metal melting industry wastes and separation of zinc and lead in the leach solution

In this work, a thorough examinations on the extractability of zinc and lead present in the steelmaking dusts using alkaline leaching process and the effectiveness of the zinc and lead separation in the resultant leaching solutions using sulfide precipitation method were made. It was found that only about 53% of zinc and over 70% of the lead could be leached out of the dusts, while the other 47% of zinc and 30% of lead were left in the leaching residues. The zinc and lead in the resultant leaching solution can be effectively and selectively separated. When the weight ratio of sodium sulfide (M.W. = 222-240) to Pb was kept at 1.8, the lead in the solution could be precipitated out quantitatively while all the zinc was remained in the solution. The zinc left in the solution can be further recovered by the addition of extra sodium sulfide with a weight ratio of sodium sulfide to the zinc over 2.6. The resultant filtrate can be recycled to the leaching of dust in the next leaching process.

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.

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...

Effects of Cadmium, Lead, and Zinc on Size of MicrobialBiomass in Red Soil

A laboratory incubation experiment was conducted to study the influence of cadmium (Cd), lead (Pb)and zinc (Zn) on the size of the microbial biomass in red soil. All the three metals were applied, separately,at five different levels that were: Cd at 5, 15, 30, 60 and 100 μg g-1; Pb at 100, 200, 300, 450 and 600 μg g-1 and Zn at 50, 100, 150, 200 and 250 μg g-1 soil. In comparison to uncontaminated soil, the microbial biomass carbon and biomass nitrogen decreased sharply in soils contaminated with Cd, Ph and Zn. A more considerable increase in the microbial biomass C: N ratio was observed in the metal contaminated soils than the non-treated control. Among the tested metals, Cd displayed the greatest biocidal effect followed by Zn and Pb, showing their relative toxicity in the order of Cd > Zn > Pb.

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.

Effect of Lead-Zinc Interaction on Size of Microbial Biomass in Red Soil

A laboratory incubation experiment was conducted to evaluate the effects of lead and zinc applied alone or in various combinations on the size of microbial biomass in a red soil. Treatments included the application of lead at six different levels i.e., 0 (background), 100, 200, 300, 450 and 600 μg g -1 soil along with each of the four levels of zinc (0, 50, 150 or 250 μg g -1 soil). Application of lead or zinc alone to soil significantly ( P <0.001) affected the soil microbial biomass. The microbial biomass carbon (C mic ), biomass nitrogen (N mic ) and biomass phosphorus (P mic ) decreased sharply in soils contaminated with lead or zinc. Combined application of lead and zinc resulted in a greater biocidal effect on soil microbial biomass, which was significantly higher ( P <0.001) than that when either lead or zinc was applied alone. Consistent increase in the biomass C:N and decline in the biomass C:P ratios were also observed with the increased metal (Pb and Zn) toxicity in the soil.

Leaching of lead from zinc leach residue in acidic calcium chloride aqueous solution

A process with potentially reduced environmental impacts and occupational hazards of lead-bearing zinc plant residue was studied to achieve a higher recovery of lead via a cost-effective and environmentally friendly process. This paper describes an optimization study on the leaching of lead from zinc leach residue using acidic calcium chloride aqueous solution. Six main process conditions, i.e., the solution pH value, stirring rate, concentration of CaC12 aqueous solution, liquid-to-solid （L/S） ratio, leaching temperature, and leaching time, were inves- tigated. The microstructure and components of the residue and tailing were characterized using scanning electron microscopy （SEM） and X-ray diffraction （XRD）. On the basis of experimental results, the optimum reaction conditions were determined to be a solution pH value of 1, a stirring rate of 500 r·min-1, a CaC12 aqueous solution concentration of 400 g·L-1, a liquid-to-solid mass ratio of 7：1, a leaching tempera- ture of 80℃, and a leaching time of 45 min. The leaching rate of lead under these conditions reached 93.79%, with an iron dissolution rate of 19.28%. Silica did not take part in the chemical reaction during the leaching process and was accumulated in the residue.

Recovery of zinc and lead from Yahyali non-sulphide flotation tailing by sequential acidic and sodium hydroxide leaching in the presence of potassium sodium tartrate

The recovery of zinc and lead from Yahyali non-sulphide flotation tailing using sulfuric acid followed by sodium hydroxide leaching in the presence of potassium sodium tartrate was experimentally investigated.In the acidic leaching stage,the effects of pH,solid-to-liquid ratio and temperature on the dissolution of zinc from the tailing were explored.82.3%Zn dissolution was achieved at a pH of 2,a temperature of 40°C,a solid-to-liquid ratio of 20%and a leaching time of 2 h,whereas the iron and lead dissolutions were determined to be less than 0.5%.The sulfuric acid consumption was found to be 110.6 kg/t(dry tailing).The leaching temperature had no beneficial effect on the dissolution of zinc from the tailing.The acidic leach solution was subjected to an electrowinning test.The cathode product consisted of 99.8%Zn and 0.15%Fe.In the alkaline leaching stage,the Pb dissolution increased slightly in the presence of potassium sodium tartrate.More than 60%of Pb was taken into the leach solution when the leaching temperature increased from 40 to 80°C.The final leach residue was analyzed by XRD and XRF.The XRD results indicated that the major peaks originated from the goethite and quartz while minor peaks stem from smithsonite and cerussite.The XRF analysis demonstrated that the residue contained 70.3%iron oxide.Based on the sequential leaching experiments,the zinc and lead were excellently depleted from the flotation tailing,leaving a considerable amount of iron in the final residue.

Bioremediation of lead by lead-resistant microorganisms, isolated from industrial sample

Lead contamination in water is a widespread problem throughout the world and results from industrial use and processing of lead ore. Bio-availability of lead can be hazardous for children and causes mental retardation. The use of lead free petrol is one measure to check this pollution, but this heavy metal is also present in industrial effluents and need to be removed before these effluents are discharged to natural land or water and as well as to the environment. Using bioremediation, bacteria could render lead non-bioavailable would provide an alternative option for detoxifying this contaminant in the environment. The property of some species of bacteria and algae, to extract metals from their surroundings, has been utilized to purify industrial effluents. The first step in devising a bioremediation strategy is to identify candidate bacterial strains capable of modifying the contaminant. Biotechnological approaches are recommended for extraction of metal forms can be grown in ponds where effluents (rich in heavy metals) are discharged. The microbes will extract the heavy metals and sequester them inside their cell membranes. The goal of the present study was to examine the capacity of lead resistant bacteria and bioremediation of lead contaminated water.

Study on the response of wheat to lead, cadmium and zinc

The effect of lead, cadmium and zinc on the transcriptions and structures of 5 DNA fragments was studied by RNA slot blot hybridization and the analysis of restriction fragment length polymorphism (RFLP). The seeds of three wheat strains (Yunmai29, 1257, 5118) which had grown in contaminated area, Huize Lead Zinc Mine, Yunnan Province of China and in uncontaminated area were taken as the experimental materials. No obvious change of DNA structure was detected, but there were many differences in the DNA transcription levels. These results implied that lead, cadmium and zinc might inhibit DNA transcription and had much more effect on gene expression than structure in wheat, which might acclimate to metal pollution after having grown in pollution area for a long time and the interference of these metal ions in gene expression might be one of main mechanisms of metal toxicity and plant adaptation. The results also showed the microevolution of wheat in the lead zinc mine.

Effects of EDTA and DTPA on Lead and Zinc Accumulation of Ryegrass

The tailing ponds of lead-zinc mines are artificial environment pollution sources, and also important dangerous sources of heavy metal contamination in lead-zinc mining areas. To study the effects of Ethylene Diamine Tetracetic Acid (EDTA) and Diethylene Triamine Penlaacetic Acid (DTPA) on phytoremediation of lead-zinc mining area soil, two chelators (EDTA and DTPA) were used in enrichment plant ryegrass to improve the uptake of Pb and Zn from soil. The results showed that when the doses of 0, 0.5, 1 and 2 mmol/kg EDTA and DTPA were used, the biomass of ryegrass (Lolium multiflorum Lam.) and its nutrient (N, P, K, Ca and Mg) content increased, whereas EDTA and DTPA with a dose of 4 mmol/kg decreased the biomass of ryegrass and its nutrient (N, P, K, Ca and Mg) content. EDTA and DTPA significantly enhanced the contents of Zn and Pb in ryegrass as compared with the control. As for Pb, the content of Pb in root and shoot reached a maximum of 2730.54 and 2484.42 mg/kg respectively when the dose of EDTA and DTPA was 2 mmol/kg. In the case of Zn, the content of Zn in root and shoot reached a maximum of 2428.37 and 2010.43 mg/kg respectively. The total Pb and Zn accumulations and translocation ratio in ryegrass had also been enhanced. The results indicated that EDTA and DTPA had great potential to be used for ryegrass to remedy Pb and Zn contamination soil of lead-zinc mining area, but should be used cautiously because of their environmental risks.

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.

Order of sphalerite and galena precipitation: A case study from lead-zinc deposits in southwest China

Most of the lead and zinc deposits in Southwest China, are characterized by mineral zoning, which is especially true for the Huize and Zhaotong deposits. The mineral assemblage zoning is consistent for both horizontal and vertical zoning, from the base(center) of the ore body to the top(outermost), the mineral zones are as follows. I-1: coarse-grained pyrite and a little puce sphalerite;I-2: brown sphalerite, galena, and ferro-dolomite;I-3: galena, sandy beige and pale yellow sphalerite, and calcite;and I-4: fine-grained pyrite, dolomite, and calcite. Among them, sphalerite is the landmark mineral of different zoning. From I-1 to I-3, the color of sphalerite changes from dark to light, its crystalline size changes from coarse to fine, and its structure changes from disseminated to veinlet. This mineral zoning is seen not only on a microscopic scale, but is also clear on a mesoscopic and macroscopic scale. It is caused by the order of the sphalerite and galena precipitation. We studied the metallic minerals and fluid inclusions using a thermodynamic phase diagram method, such as lgfO2–lgfS2, pH–lgfO2, pH–lg[Pb^2+] and pH–lg[HS^-], discussed the constraints on the order of the sphalerite and galena precipitation in the migration and precipitation process of lead and zinc under different pH values, oxygen fugacity, sulfur fugacity, and ionic activity. We also explain the formation mechanism and propose that the main controlling factor of the order of the sphalerite and galena precipitation is sulfur fugacity.

Lead Pollution Research of Resident Children around Some Industrial Park

Lead is an important toxic heavy metal among environment pollution. Some industrial parks were founded in 2005 including non-ferrous metal processing and smelting plants. In order to identify the consequence of lead pollution on children around the industry park, blood samples of neighboring children were collected and analyzed in laboratory. The results showed that the involved children have suffered serious harms from Pb pollution. Almost 75% of the children＇s blood lead levels （BLLs） exceeded the limit of normal blood lead. Worse still, 26.17% of them were at the level of Moderate lead poisoning. The group aged 0-7 showed more susceptibility to Pb than that aged 8-14. Only 19.05% of the children aged 0-7 were at the level of normal blood lead, compared with 45.45% in the group aged 8-14. There was no significant difference between the values of blood lead concentration for male and female or among different age groups. Some approaches, which include controlling the Pb pollution from the industry park and safeguarding the residents, esp. the children were suggested.

Evaluation of Lead Exposure by Hand Wipes: A Review of the Effectiveness of Personal Hygiene on Industrial Sites

To evaluate the effectiveness of personal hygiene (handwashing) amongst workers at industrial sites to remove lead from their hands, a retrospective analysis of hand wipe samples was conducted using data collected by two contractors from two bridge painting projects for total lead using method ASTM E-1979-17/EPA SW846 7000B. Exposures resulted from the removal of lead-based paint from the structure and trace elements of lead found in the abrasive blast media. In total, six work tasks were evaluated and sixty unique hand wipe samples were evaluated. Thirty samples were collected during the worker’s lunch break, after they had reportedly washed their hands with a further 30 collected at the end of the workday following the same protocol. To be included in this evaluation, the contractors were required to follow NIOSH Method 9105 (Lead in Dust Wipes-Dermal Surfaces) with subsequent analysis of samples for total lead by an American Industrial Hygiene Association (AIHA) accredited laboratory. All 60 samples contained detectable lead. The lead exposures ranged from 19.5 μg to 3420 μg. The geometric mean for the samples collected was 337 μg. These results indicate that current personal hygiene practices at the evaluated sites are not effective at removing lead from worker’s hands during and after the workday. They also suggest that the residual lead measured on the workers’ hands, at the end of the shift, is likely contributing to the elevated blood lead levels in this population.

An experimental study on metal precipitation driven by fluid mixing: implications for genesis of carbonate-hosted lead–zinc ore deposits

A type of carbonate-hosted lead–zinc(Pb–Zn)ore deposits, known as Mississippi Valley Type(MVT)deposits, constitutes an important category of lead–zinc ore deposits. Previous studies proposed a fluid-mixing model to account for metal precipitation mechanism of the MVT ore deposits, in which fluids with metal-chloride complexes happen to mix with fluids with reduced sulfur, producing metal sulfide deposition. In this hypothesis, however, the detailed chemical kinetic process of mixing reactions, and especially the controlling factors on the metal precipitation are not yet clearly stated. In this paper, a series of mixing experiments under ambient temperature and pressure conditions were conducted to simulate the fluid mixing process, by titrating the metal-chloride solutions, doping withor without dolomite, and using NaHS solution. Experimental results, combined with the thermodynamic calculations, suggest that H_2S, rather than HS^-or S^(2-),dominated the reactions of Pb and/or Zn precipitation during the fluid mixing process, in which metal precipitation was influenced by the stability of metal complexes and the pH. Given the constant concentrations of metal and total S in fluids, the pH was a primary factor controlling the Pb and/or Zn metal precipitation. This is because neutralizing or neutralized processes for the ore-forming fluids can cause instabilities of Pb and/or Zn chloride complexes and re-distribution of sulfur species, and thus can facilitate the hydrolysis of Pb and Zn ions and precipitation of sulfides. Therefore, a weakly acidic to neutral fluid environment is most favorable for the precipitation of Pb and Zn sulfides associated with the carbonate-hosted Pb–Zn deposits.