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• Cd and Hg were the most polluted HMs in the study area. • ZZ3 and ZZ7 were the most polluted workshops and required priority control. • GIS, PMF, and APCS-MLR models were used to analyze the precise sources of HMs. • Cd and Hg were respectively derived from smelting process and atmospheric deposition. The abandoned smelters present a substantial pollution threat to the nearby soil and groundwater. In this study, 63 surface soil samples were collected from a zinc smelter to quantitatively describe the pollution characteristics, ecological risks, and source apportionment of heavy metal(loid)s (HMs). The results revealed that the average contents of Zn, Cd, Pb, As, and Hg were 0.4, 12.2, 3.3, 5.3, and 12.7 times higher than the risk screening values of the construction sites, respectively. Notably, the smelter was accumulated heavily with Cd and Hg, and the contribution of Cd (0.38) and Hg (0.53) to ecological risk was 91.58%. ZZ3 and ZZ7 were the most polluted workshops, accounting for 25.7% and 35.0% of the pollution load and ecological risk, respectively. The influence of soil parent materials on pollution was minor compared to various workshops within the smelter. Combined with PMF, APCS-MLR and GIS analysis, four sources of HMs were identified: P1(25.5%) and A3(18.4%) were atmospheric deposition from the electric defogging workshop and surface runoff from the smelter; P2(32.7%) and A2(20.9%) were surface runoff of As-Pb foul acid; P3(14.5%) and A4(49.8%) were atmospheric deposition from the leach slag drying workshop; P4(27.3%) and A1(10.8%) were the smelting process of zinc products. This paper described the distribution characteristics and specific sources of HMs in different process workshops, providing a new perspective for the precise remediation of the smelter by determining the priority control factors. [Display omitted] [ABSTRACT FROM AUTHOR]

This paper presents the results of the development of stabilization measures aimed at the removal of zinc with the products of melting and accumulation of titanium in the hearth of a blast furnace. The relevance of the development and use in practice of such measures is due to the unstable fuel and raw materials conditions for the production of cast iron, when their stabilization is a complex and difficult task, as well as the need to extend the campaign of blast furnaces during the overhaul period. The negative effect of zinc oxides on the condition of the blast furnace shaft lining, accompanied by slab formation, and the overconsumption of specific coke consumption, which occurs when zinc circulates in the volume of the blast furnace, require measures to remove zinc from the smelting products. The article proposes such measures, which consist of flushing according to the proposed schedule during the operation of the blast furnace at planned blowing parameters and with the provision of the necessary thermal reserve. In order to lengthen the campaign of a blast furnace, one of the most common methods for protecting the hearth lining is the periodic introduction of titanium‐containing materials into the charge of blast furnaces. The entry of titanium oxides into the furnace, as a rule, is ensured by the use of concentrate or specially prepared ilmenite briquettes with a high titanium content as part of the sinter charge, which can be introduced directly into the composition of the blast furnace charge. The article analyzes the experience of using titanium‐containing materials as part of a blast furnace charge and formulates measures to intensify skull formation in the hearth. [ABSTRACT FROM AUTHOR]

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Zinc oxygen pressure leaching process is characterized by direct wet oxygen pressure leaching of zinc sulfide concentrate. Sulfur does not enter the flue gas, but is directly converted into elemental sulfur recovery. The production process is simpler, environmentally friendly, low comprehensive energy consumption, and the sulfur products are relatively easier to store, transport and sell. Therefore, the promotion and application of this technology is of great significance to the realization of energy conservation and emission reduction in zinc smelting industry and even the goal of emission peak and carbon neutrality. The effects of mineral characteristics, metal leaching rate, sulfur acidification rate, sulfur crystallization process control, sulfur flotation efficiency and thermal filtration temperature of sulfur concentrate on sulfur recovery were studied. [ABSTRACT FROM AUTHOR]

Heavy metal pollution has been a serious risk in the Indigenous Zinc Smelting in Northwest Guizhou, China. Long-term open-air stacking of waste slag has also led to a great increase in the heavy metal reactivity under suitable environmental conditions after leaching, thus continuously migrating to the surrounding groundwater, surface water, and soil. A substantial amount of mining slag has been left behind, due to outdated technology and extensive production. Therefore, it is very urgent to clarify the contamination status of heavy metals in the soil, water bodies, and sediments in the areas, particularly with the concentrated distribution of Indigenous Zinc Smelting slag and their potential ecological risks, in order to protect the local land and water resources for the food safety and public health. This study focused on an 8 km2 area with a relatively wide distribution of Indigenous Zinc Smelting slag from traditional smelting areas. Human pollution sources were avoided to collect the surface soil samples within a grid of 1/9 km2. The background levels of heavy metals in surface soils were established over the region. Some samples were collected from the smaller watersheds, including surface soil, sediment from water systems, leachate, mine slag, and water bodies, according to the hydrogeological and topographical conditions. Additionally, the samples of deep soil profile were gathered from the site, where the largest amount of mine slag was stored for the longest time. The content of heavy metals and pH value were measured in various samples using the single-factor pollution index, Nemerow comprehensive pollution index, and potential ecological risk index. The spatial distribution and pollution status of heavy metals were analyzed in different media. The results show that the surface soil in the study area was mainly acidic, where the average contents of As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn were 23.54, 3.20, 208.78, 193.02, 0.07, 91.41, 315.80, and 479.13 mg/kg, respectively. Except for Hg and pH, the contents of the rest elements were higher than the background value of surface soil in the Bijie region. The contents of As, Cd, Cr, Cu, Ni, Pb, and Zn exceeded the national environmental background values of surface soil. The overall slag was neutral with the average contents of As, Cd, Cu, Hg, Pb, and Zn higher than the average value of surface soil in the study area. Especially Pb, the raw materials used in local traditional zinc smelting were imported the lead-zinc ores. The soil profile samples show that the heavy metals were mainly concentrated in the surface soil of 0-20cm, whereas, the heavy metals in deep soil were mainly controlled by geological background and primary soil. The highest contents of As, Cd, Cu, Pb, and Zn in small watershed sediments were 274, 11.90, 488, 2340, and 2580 mg/kg, respectively, all of which were located in the central area of traditional zinc smelting slag. The highest contents of Cr, Cu, Ni, Pb, and Zn in the surface water of a small watershed were distributed downstream of the slag concentrated distribution area, which were 43.60, 64.90, 15.70, 226.00, and 223.00 mg/L, respectively. Only Ni was slightly higher than the content of slag leachate in groundwater. The contents of the rest elements were lower than those in the leachate. Single-factor evaluation was performed on the pollution of heavy metals in the surface soil. The Cd and Cu shared the highest proportion of pollution, with the Cd in the widest range of pollution. The Nemerow comprehensive pollution index for heavy metals in small watershed sediments was heavily polluted by As, Cd, Cu, Pb, and Zn. The very strong potential ecological risk was only found in the central part of the traditional Indigenous Zinc Smelting slag distribution area. The Nemerow comprehensive pollution index of heavy metals in small watershed water bodies was severely polluted; The medium to very strong potential ecological risk areas were concentrated in the traditional zinc smelting slag distribution areas. There was an extremely uneven distribution of As, Cd, Pb, and Zn in the surface soil with the coefficients of variation exceeding 1.5, indicating the strong human factors. About 12.5% of the study area shared a strong ecological risk, which was mainly distributed around the waste dump site of the Indigenous Zinc Smelting plant. As such, the Indigenous Zinc Smelting slag posed a significant impact on the surrounding ecology. The pollution range of heavy metals was concentrated mainly within 2500 m in the water sediments in the small watershed; The impact of slag on groundwater was less than that on surface water, due to the restriction from the hydrogeological conditions. Overall, the pollution areas of the zinc smelting slag in the study area were mainly distributed around the centralized storage area of the slag, with a relatively limited range of impacts. [ABSTRACT FROM AUTHOR]

The article focuses on India's shift towards incorporating traditional knowledge into its education system to move away from its colonial legacy, with a particular emphasis on the inclusion of historical achievements like zinc distillation. Topics include the debate over whether the new curriculum will correctly represent India's diverse cultural heritage, concerns about potential bias and misinformation, and the practical challenges and responses from various institutions and educators.

In zinc smelting solution, because the concentration of zinc is too high, the spectral signals of trace copper are masked by the spectral signals of zinc, and their spectral signals overlap, which makes it difficult to detect the concentration of trace copper. To solve this problem, a spectrophotometric method based on integrated and partition modeling is proposed. Firstly, the derivative spectra based on continuous wavelet transform are used to preprocess the spectral signal and highlight the spectral peak of copper. Then, the interval partition modeling is used to select the optimal characteristic interval of copper according to the root mean square error of prediction, and the wavelength points of the absorbance matrix are selected by correlation-coefficient threshold to improve the sensitivity and linearity of copper ions. Finally, the partial least squares integrated modeling based on the Adaboost algorithm is established by using the selected wavelength to realize the concentration detection of trace copper in the zinc liquid. Comparing the proposed method with existing regression methods, the results showed that this method can not only reduce the complexity of wavelength screening, but can also ensure the stability of detection performance. The predicted root mean square error of copper was 0.0307, the correlation coefficient was 0.9978, and the average relative error of prediction was 3.14%, which effectively realized the detection of trace copper under the background of high-concentration zinc liquid. [ABSTRACT FROM AUTHOR]

Steel mill dust (SMD), produced by electric arc furnaces, is a highly polluting industrial waste due to its high content of metals (Zn, Fe, and Pb) and fine particle size (ca. 5.4 µm). This residue can be valorized to recover Zn using pyro and hydrometallurgical methods, with hydrometallurgy offering greater selectivity and lower energy costs. However, composition of SMD presents a challenge in identifying an optimal leaching agent. This study investigates the preferential extraction of Zn using two leaching agents, namely 150 g L−1 (1.5 M) phosphoric acid (H3PO4) and 240 g L−1 (6 M) sodium hydroxide (NaOH), in a two-stage leaching process (80 °C). Metallic Zn from the alkaline pregnant solution was recovered by electrodeposition (750 A/m2, graphite anode, stainless-steel cathode) and smelting (450 °C). The samples of SMD contained 26.3% Zn, 20.1% Fe, and 0.9% Pb, in compounds such as magnetite (Fe3O4), zincite (ZnO), and franklinite (ZnFe2O4). Each leaching agent successfully attained a 99% Zn recovery, demonstrating the proposed procedure's high efficacy. However, H3PO4 leached also Fe and corroded the cathode during electrodeposition, thereby restricting the final recovery of metallic Zn. NaOH demonstrated greater selectivity for Zn over Fe and Pb, producing high-purity Zn deposits on the cathode by electrodeposition and 99% metallic zinc by smelting. [ABSTRACT FROM AUTHOR]

This study was conducted in Hezhang County, Bijie City, Guizhou Province. The soil in the zinc smelting area has been contaminated with cadmium, lead, and zinc. Therefore, these elements are the focus of this research. Rice husk biochar was used as the passivation material. The Fourier infrared spectrum was utilized to study the biochar's morphology, element content, mineral composition, structure, and surface functional groups. Moreover, the physical and chemical properties of the biochar were analyzed to explore its passivation effect. Biochar is beneficial in the cleaning of cadmium, lead, and zinc minerals and can be used for the passivation of heavy metals in contaminated soil. This study aims to understand the detailed mechanism behind this process and provide experimental data and ideas for pollution control. The results indicate that the biochar contains many functional groups, including -OH, C-H, C-O, C=O, C=C, and C-O-C. It also consists of a significant quantity of potassium salt, calcite, and quartz. Biochar has a noticeable pore structure, and as the pyrolysis temperature increases, the pore structure becomes more developed and thinner, with a smooth surface. The main minerals in the soil are quartz, mica, zeolite, illite, and chlorite. The aromatic degree of biochar increased with pyrolysis temperature. In contrast, the aromatic degree and polarity first increased and then decreased. The 0.2-0.45 mm biochar exhibited the best passivation effect on cadmium, lead, and zinc. [ABSTRACT FROM AUTHOR]

The high-temperature roasting/smelting process of copper and zinc concentrates will cause the mercury in the concentrate to evaporate into the flue gas, and most of the mercury in the flue gas will eventually enter the waste acid in its ionic form. A highly efficient mercury removal agent M201 with long carbon chains and loaded active functional groups can adsorb and disperse fine particles for mercury removal in the system. Through bridging, the linear structure is woven into a network to achieve large-scale capture and dispersion of fine particles and colloidal substances. The recommended operating conditions for developing mercury deep purification technology are as follows: M201 reagent concentration of 50 g/L, 6 mL/L added acid solution, room temperature, mixing time of 5 min, air flotation time of 10 min, ventilation rate of 0.1 L/min, H2SO4 concentration of 33.67 g/L, and the residual mercury content of 2 mg/L (the mercury content reaches 0.01 mg/L after two-stage mercury removal treatment). Meanwhile, the residual arsenic content is 21.9 mg/L. This study shows a better separation of arsenic and mercury and achieves one-step mercury removal. [ABSTRACT FROM AUTHOR]

Cadmium (Cd) contamination in agricultural soils has emerged as a significant concern, particularly due to its potential impact on plant-based food. Soil pH reductions can exacerbate Cd mobility, leading to excessive accumulation in crops. While liming has been demonstrated as an effective method to mitigate Cd accumulation in rice grains in acid soils of southern China, its efficacy in remediating acid soils in northern China remains unclear. In this study, a multi-year field experiment was conducted on farmland impacted by zinc ore smelting at coordinates of 33.92° N 112.46° E to investigate the use of limestone for controlling Cd accumulation in wheat and maize grains. The results indicated that applying 7.5 t ha−1 of limestone significantly raised the soil pH from 4.5 to 6.8 as anticipated. Different rates of limestone application (2.25, 4.45, and 7.50 t ha−1) reduced Cd bioavailability in the soil by 20–54%, and Cd accumulation in wheat grains by 5–38% and maize grains by 21–63%, without yield penalty. The remediation effects were sustained for at least 27 months, highlighting limestone as a promising ameliorant for smelting-affected farmland in northern China. [ABSTRACT FROM AUTHOR]

Iron is commonly present as an impurity or by-product in various smelting processes. In this study, the separation and purification of iron from a zinc wet smelting leaching solution were achieved using the goethite method, which involved controlling pH and adding crystal seeds. The separated iron was then utilized as the iron source for the preparation of LiFePO4/C (lithium iron phosphate) in the form of α-FeOOH. Subsequently, LiFePO4/C was synthesized through wet ball milling and carbon thermal reduction. The physicochemical and electrochemical properties of the material were characterized using several techniques, including inductively coupled plasma-optical emission spectrometry (ICP-AES), X-ray diffractometer (XRD), field emission scanning electron microscopy (SEM), transmission electron microscope (TEM), thermogravimetric differential thermal analyzer (TG/DTA), Fourier exchange infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), and electrochemical techniques. The results indicate that the LiFePO4/C prepared using the goethite method exhibits excellent cycling properties and stability. The initial discharge capacities at various rates (0.1 C, 0.2 C, 0.5 C, 1 C, 2 C, and 5 C) were measured as 149.5, 142.6, 135.6, 131.7, 116.5, and 102.5 mAh g−1, respectively. Impressively, after 200 cycles at 1 C, the material retained 99.5% of its initial capacity. Furthermore, even after 1000 cycles at a current rate of 1 C, it still maintained 95.4% of its capacity. Therefore, this study presents a novel technical route for the recovery and recycling of iron ions, while also demonstrating the promising performance of LiFePO4/C. [ABSTRACT FROM AUTHOR]

Hydrometallurgy is the main method of zinc smelting in the world today. The zinc-leached residues produced from zinc hydrometallurgy contain zinc as well as other valuable metals such as silver, lead, copper, cadmium, indium, germanium, etc. As a tailings storage, the residues not only occupy a large amount of land space, but also cause serious losses of valuable resources. In addition, the long-term storage is highly hazardous to the environment. Therefore, it is of great significance to comprehensively recover valuable metals from the zinc-leached residues. Based on the research status at home and abroad, a review was made on this aspect in the present paper, including the process mineralogical properties of the zinc- leached residues, extraction process and development trend. [ABSTRACT FROM AUTHOR]

The regulation of the melting point of zinc smelting slag has an important impact on the subsequent smelting processes of the metal. In actual production, uncontrollable melting points may result in inconsistent product quality, which has a great negative impact on the smelter's efficiency and environmental protection. However, the regulation mechanism of the melting point of the smelting slag is complex, with many influencing factors, and there is no recognized high-precision calculation method. In response to these challenges, this study introduces an innovative approach for optimizing the melting point of zinc smelting slag based on the improved Snake Optimization (ISO) algorithm. The melting point of zinc smelting slag is modeled using the Catboost algorithm, and the model parameters are optimized using the Tree-structured Parzen Estimator (TPE) to improve the accuracy of the model. Next, the ISO algorithm is employed to conduct optimization calculations, determining the optimal values of various production process parameters that minimize the melting point. The effectiveness of this approach was evaluated using diverse modeling algorithms and test functions, subsequently applied to optimize and validate actual production data from a smelter in Shaanxi, China. Statistical analyses reveal that the TPE-optimized Catboost model exhibits an R2 of 93.89%, an RMSE of 7.02 °C, an MAE of 6.19 °C, and an MRE of 7.88%, surpassing performance metrics of alternative algorithms. Regarding optimization efficacy, the proposed ISO algorithm achieves an average reduction of 65 °C in the melting point and demonstrates superior robustness compared to both actual production data and alternative algorithms. [ABSTRACT FROM AUTHOR]

In recent years, zinc production has grown exponentially, compensating for the need arising from worldwide industrial growth. Jarosite is a non-biodegradable mineral residue obtained from smelting zinc ore. Jarosite is categorised as a hazardous material due to its high metal ion concentration, and hence, the safe disposal of massive volumes of jarosite waste poses a significant burden. This review article highlights how various proportions of jarosite affect concrete's fresh, mechanical, hydration, microstructural, and durability properties. When used in specific volumes, jarosite positively impacts the concrete compressive strength. The hydration mechanism of jarosite-incorporated concrete justifies forming a secondary hydration reaction, which causes dense morphology observed during microstructure analysis. Further, when jarosite is incorporated into concrete, the leaching characteristics of raw jarosite are observed to be substantially reduced and meet the safe limits. Based on the observations, a jarosite replacement level of 15% to the cementitious mix shows improvement in the mechanical and durability properties of the concrete. These findings could be used to identify a sustainable approach to reutilise the zinc industry waste by-products (jarosite). The experimental values of jarosite-incorporated concrete were compared with those of similar well-researched industrial waste materials such as red mud and copper slag to ensure that the observation and evaluation are accurate and trustworthy. [ABSTRACT FROM AUTHOR]

Gallium is an important dispersive metal with widespread applications in high-tech fields such as semiconductor materials, optoelectronics, and radio technology. Recently, the market demand for gallium metal has grown, given the continuous progress of science and technology. Gallium is primarily recovered as a by-product of aluminum and zinc metallurgy, accounting for approximately 90% and 10% of the total gallium production. The relatively low production share derived from zinc metallurgy is because of the high recovery difficulty. In this study, various technological routes for gallium extraction from zinc metallurgy are summarized with detailed analyses based on technological and economic perspectives. During closed blast furnace zinc smelting, >95% of Ga is enriched in water-quenched slag with an average mass fraction of 0.025%–0.031%. Several methods for extracting Ga from the slag are proposed, including reduction evaporation, chlorination volatilization, sulfuric acid leaching, caustic fusion–leaching, reduction smelting–electrolysis, and reduction smelting–slagging . However, these methods are difficult to obtain industrial applications due to long flow, low recovery, high cost, or severe pollution. During the conventional roasting–leaching–purification–electrowinning process, >93.5% of Ga remains in the leaching residue, closely associated with a ZnFe2O4 phase. Next, the reduction volatilization or hot acid leaching is employed to treat the residue. Only 10% of Ga volatilizes into the crude zinc oxide dust, whereas the other Ga remains in the kiln slag, causing huge Ga loss. Ga and Fe are dissolved into the solution through hot acid leaching, and the Ga and Fe separation is a large technological problem. Compared to roasting–leaching, pressure leaching is considered more suitable for treating the Ga-rich zinc concentrate due to the absence of a roasting procedure. Ga can be leached directly into the solution with a high reaction temperature and strong oxidization atmosphere. Before Fe removal, Ga is successfully enriched in the refining residue, with an average mass grade of >0.25%, through preneutralization and zinc powder replacement. Next, the Ga-enriching residue can be further treated by H2SO4 leaching and subsequent solvent extraction. Finally, Ga with 99% purity is produced using neutralization–sedimentation, alkaline dissolution, and electrowinning. The total recovery for Ga production from zinc concentrate to gallium product is >70%. Based on this technological route, an annual production of 15 t Ga is established in the Danxia smelter. In this research, the gallium distribution behavior among the multiphase during various procedures such as roasting, leaching, replacement, and sedimentation is clarified carefully, and a reasonable technological route for enriching Ga from zinc metallurgy is proposed. Moreover, the methods for separation and enrichment of Ga from the leaching solution are summarized. The development of solvent extraction, emulsion film, and resin adsorption should be the key progress for green and efficient Ga recovery from zinc metallurgy.

In the long-term production process of lead and zinc smelting enterprises, atmospheric subsidence leads to the accumulation of heavy metals in surrounding farmland, which poses a serious threat to the growth of crops and food safety. Given the knowledge that heavy metal pollution in cultivated land does not support treatment and restoration, determining how to ensure the quality and safety of agricultural products is the main problem facing the agricultural industry at present. Previous studies have mainly focused on the low accumulation of heavy metals in maize varieties, while the removal of heavy metals from soil through high biomass has been studied less. In order to identify the maize varieties that demonstrate high removal and low accumulation of heavy metals, 29 maize varieties were planted in soil contaminated with lead (Pb) and cadmium (Cd), and the growth status of the maize varieties and the absorption and transport of Pb and Cd by different tissues were studied. The results showed that heavy metals had the least effect on the growth of the Longhuangbai3, Jinqiuyu 35, Jinyi 418, and Qiuqing 88 varieties, and the content of Pb and Cd in maize varieties was in the order leaf > stem > root > grain. It was found that soil remediation and safe production can be taken into account in the results of the Qiuqing 88 (Pb, Cd), Fengdeng 2025 (Cd), and Yayu 719 (Pb, Cd) varieties. Moreover, the Xinzhongyu 801 (Cd) and Longdan 1701 (Pb) varieties demonstrated high metal accumulation in the edible part, which poses a potential risk to human health; thus, they are not recommended for local cultivation. [ABSTRACT FROM AUTHOR]

This article presents the mineralogical and chemical characteristics of zinc and lead smelting slags, with particular reference to the slags formed during the simultaneous production of Zn and Pb by the Imperial Smelting Process. These slags, because of the presence of many metals in their composition, mainly in the form of crystalline phases, are a valuable source for their extraction. Slags from Zn-Pb metallurgy are processed on an industrial scale using pyrometallurgical and hydrometallurgical methods, alongside which a number of experiments conducted to recover metals as efficiently as possible, including bioleaching experiments. [ABSTRACT FROM AUTHOR]

The column leaching experiments were carried out under different leaching conditions of flooding water, alternating dry and wet (ADW), and continuous leaching with simulated acid rain of pH 4.4 for 30 days to study the release, migration, and transformation characteristics of Cd and Pb in the soil profile from a zinc smelting site. The results showed that the leachate concentrations of Cd and Pb from all treatments reached a peak value on the 5th day of early leaching stage, and then gradually decreased. The peak Cd concentration ranged from 21.7 to 45.1 μg/L, which exceeded the threshold limit of Cd (10 μg/L) of Standard for Groundwater Quality (GB/T 14848-2017). Moreover, the Cd concentration from AF treatment was higher than the Cd threshold limit throughout the whole leaching period, indicating that there was Cd pollution risk of groundwater. The peak value of leachate Pb concentration ranged from 0.90 to 2.69 μg/L, which was much lower than the threshold limit for Pb (100 μg/L). Acid rain leaching promoted the release and migration of Cd and Pb in the upper layer of miscellaneous fill soil (0~10 cm), which were predominately accumulated in the plain fill soil of 15~20 cm depth, and Cd showed a higher migration depth than Pb. The results of three-step sequential extraction method formulated by the European Community Bureau of Reference showed that the residual fraction of Cd and Pb in the surface soil after leaching was decreased, and their exchangeable fraction was increased showing high mobility. The exchangeable fraction percentage of Cd and Pb in the deeper soil (10~60 cm) was decreased, and their residual fraction percentage was increased. ADW treatment promoted the transformation of Cd and Pb in soil to the exchangeable fraction, and the potential pollution risk to the surrounding soil and groundwater was increased. Rainfall, especially acid rain leaching can cause the release and migration of Cd and Pb in soil from the smelting site, then result in increasing the risk of groundwater pollution. The results can provide scientific basis for risk management and remediation of heavy metal contaminated soil from smelting sites. [ABSTRACT FROM AUTHOR]

To assess the effect of zinc smelting on environment and human health, the concentration, distribution, sources and health risk of eight heavy metals (Pb, Cd, Cu, Zn, Cr, Ni, Mn, and As) were investigated from agricultural soils in a long-term Zn smelting area in Guizhou, China. Different health risk assessment methods and models were used to access health risks. The results show that the concentrations of all the eight heavy metals were significantly higher than their corresponding background values (p < 0.05). Pb, Cd, and As were the most contaminated elements, with 93.6%, 90.3% and 48.4% of agricultural soil samples higher than the risk screening values, respectively. Statistical analysis indicated that Pb, Cd, Cu, Zn, Mn, and As could be mainly accounted for Zn smelting activities, while Cr and Ni may be generally more controlled by natural sources. The geo-accumulation index (Igeo) suggested that the most seriously contaminating heavy metals were Pb, Cd, and Zn, with 96.8%, 90.3%, and 96.8%, respectively, of the soil samples classified as moderately to extremely contaminated. The non-carcinogenic health risk associated with Pb, Cd and As were observed for children, meanwhile, the carcinogenic risk due to As was found for both adults and children. Regardless of cancer risk or non-cancer risk, local children are at greater risk than adults. Therefore, Pb, Cd and As play the leading role to cause potential health risks in the study area, which need to be paid more attention and also effective control measures should be taken. [ABSTRACT FROM AUTHOR]

With the continuous strict environmental protection requirements in our country and the fierce competition of zinc smelting enterprises, a reasonable and economical choice of tail gas desulfurization system can greatly enhance the competitiveness of enterprises in the market. This article compares zinc oxide desulfurization with conventional desulfurization technology, systematically analyzes the advantages of zinc oxide desulfurization technology in zinc smelting, points out its problems in actual production, and proposes solutions. The paper provides certain theoretical and practical guidance for zinc oxide desulfurization technology application in zinc smelting enterprises.

The farmland around the industrial areas in the Upper Yellow River is crucial for agricultural production but is vulnerable to contamination from the surrounding industries. This research focused on analyzing the spatial distribution and environmental risks of heavy metal pollution in the farmland around the Ganhe Industrial Park in the Qinghai–Tibet Plateau. A total of 138 surface soil samples were collected, and the concentration of seven heavy metals (Cd, As, Pb, Cr, Cu, Ni, and Zn) was analyzed using the random forest (RF) model. Pollution indicators, including the pollution index and Nemero index, were used to evaluate the pollution levels of soil heavy metals. The human health and ecological risks were estimated using the hazard index (HI) and the potential ecological risk index (RI). Cd and Zn were identified as the primary soil pollutants in the study area, with Cd being more concentrated than other heavy metals. Heavy metal contamination was most severe in the central–eastern region of the study area, with a ring-shaped distribution, which correlated with the presence of zinc smelting and chemical plants. Furthermore, the study revealed that soil heavy metal contamination posed a health threat to the local population, with children being particularly vulnerable to non-carcinogenic risks when the HI was 1.21 and to potential carcinogenic risks when the CR was 2.27 × 10−5. Additionally, heavy metal pollution caused a moderate to high ecological risk in 56.4% of the samples. The results highlighted the severe impact of soil heavy metal pollution on the delicate ecosystem of the Upper Yellow River and Qinghai–Tibet Plateau. The government should take action to improve soil environment management and prevent heavy metal pollution to protect the health of the local population and the ecological environment. [ABSTRACT FROM AUTHOR]

Roaster furnace is a large-scale equipment in zinc smelting process, which plays an significant role in safety production and enviromental protection. An accurate digital twin of roaster furnace can help to explore the influence of control parameters and serve as a test platform to verify the effectiveness of control strategies. However, the traditional thermodynamics cannot be used for dynamic modeling, and inability to measure key data greatly affects the accuracy of kinetic modeling. Therefore, this paper establishes a novel digital twin of zinc roaster furnace based on knowledge-guided variable-mass thermodynamics. First, based on the integration of mechanism analysis for mass balance and energy balance, a dynamic modeling method is proposed. Then, particle swarm optimization (PSO) algorithm is introduced to optimize the parameters of conversion rates guided by knowledge. Finally, by connecting the dynamic model with distributed control system (DCS) through OPC communication protocol, a digital twin of roaster furnace is constructed. Extensive experiments show that the simulation results of the digital twin roughly agree with the actual industrial data under steady and dynamic working conditions, and the application of the digital twin on the performance analysis of control parameters and testing of control strategies can provide guidance for the optimal control of roaster furnace. [ABSTRACT FROM AUTHOR]

Introduction: In developing countries, Material Flow Cost Accounting (MFCA) offers numerous benefits, including the identification of hidden costs, waste reduction, improved environmental outcomes, enhanced product quality and competitiveness, and increased process and resource productivity. The zinc mining industry and related activities, such as concentrate production and zinc smelting, require process life cycle analysis due to the extensive pollution they generate, including contamination of surface and underground water from heavy elements in the leachate. Through the use of MFCA modeling, it is possible to accurately evaluate the inputs and outputs of current processes in this field and analyze them for environmental effects.Materials and Methods: This study involved visits to industrial smelting units, expert opinions, and integration with the Sima Pro software database to prepare a life cycle model and network of the product life cycle and its environmental effects. By analyzing the life cycle of Iran's zinc smelting industry, green product productivity was used to calculate the cost-material flow in the selected sample unit, track the material flow, and present a model for the life cycle of zinc. This involved utilizing information from Iran's zinc smelting industry, data from the Sima Pro software database, and the implementation of the MFCA model on information related to zinc smelting and concentrate products. In this model, zinc smelting and zinc concentrate production processes were treated as input and greenhouse gas emissions as output.* Corresponding Author’s email: Sarkheil@khu.ac.ir Results: Based on the material balance relationship, the combination of calcine with sulfuric acid produces leach cake, silver, lead, and air pollution. The research estimates that for the production of one ton of zinc ingot, the amount of air pollution generated is 7 kg. MFCA analysis of the leaching unit of the industrial research complex indicates that the cost of 5070 kilograms of input materials is 12,350,000 Tomans, the cost of the system is 30,000,000 Tomans, and the cost of energy is 1,950,000 Tomans. The study also found that 3549 kg of product is obtained for 9,100,000 Tomans, while 1536 kg of waste is produced at the cost of 3,250,000 Tomans. This highlights the input values, the primary product, and the secondary product.Discussion: Through the provision of comprehensive life cycle models for the zinc smelting process, especially the zinc smelting concentrate process, the inputs and outputs of the production chain were evaluated. By accurately determining the flow cost of these materials, the process of zinc smelting concentrate production can be optimized to minimize losses, reduce environmental pollution, lower direct costs, and increase economic output, thereby leading to the growth and development of the industrial complex.

Sulfur dioxide (SO2) is a toxic pollutant and its fixation is a high cost but imperative task for sulfide metallurgy industry. Although being a mature technology for on-line fixation of SO2 by limestone injection in coal-fired boilers, its application is rarely investigated in the sulfide metallurgy plant. Extending this technology to the metallurgy industry is highly plausible, but with the feasibility and practicability waiting to be uncovered. Herein, feeding CaO into the rotary volatilization kiln as SO2-fixation agent is demonstrated to be an efficient in-furnace desulfurization strategy for zinc smelting plant. The sulfur distribution within the entire smelting process is systematically analyzed, determining that the critical procedure for pressuring the desulfurization system is the rotary volatilization kiln. The thermodynamics analysis shows that addition of CaO is feasible for SO2 fixation by forming CaS or restraining the reductive decomposition of SO42−. The industrial tests, including the online monitoring of kiln flue gas and kiln slag analysis, validate the thermodynamics analysis, realizing a 24.6% reduction of SO2 in the flue gas by converting gaseous SO2 to solid CaS via feeding 20% CaO. The present study highlights an effective strategy for on-line fixing the SO2, being a potential way for relieving the desulfurization pressures in zinc sulfide metallurgy plant. [ABSTRACT FROM AUTHOR]

In the process of zinc smelting, when the chloride ion concentration exceeds 100 mg/L, it continuously corrodes the electrode plate and affects the stability of the electrodeposition process. Therefore, the chloride concentration must be reduced below 100 mg/L. Compared with other methods used to control the reactions of Cu(II), the use of the copper slag produced in zinc smelting without other additives does not cause reverse dissolution; to reduce the cost, turn the waste into treasure, and protect the environment, research was carried out on chloride removal by the copper slag via a synergistic valence control process. In this study, the influencing factors, such as the amount of copper slag, the reaction time, and reaction temperature, were systematically investigated. The results showed that the optimum dechlorination conditions were as follows: the copper: copper(II): chloride molar ratio was 6:5:1, the reaction time was 60 min, and the reaction temperature was 20 °C. The chloride ion concentration was decreased from 1.6 g/L to 0.05 g/L, the dechlorination efficiency was 96.875%, and the residual chloride ion concentration was less than 100 mg/L, which provides a basis for industrial use. [ABSTRACT FROM AUTHOR]

Copyright of Mining & Metallurgy (10057854) is the property of Beijing Research Institute of Mining & Metallurgy Technology Group and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The direct and rapid determination of trace cobalt ion (Co2+) in the electrolyte of zinc smelting plants is urgently needed but is impeded by the severe interference of extremely high-concentration zinc ions in the solution. Herein, colorimetric detection of Co2+ by the polyvinylpyrrolidone functionalized silver nanoparticles (PVP-AgNPs) is realized in solutions with the Zn/Co ratio being high, up to (0.8–5) × 104, which is located within the ratio range in industrial solution. The high concentration of Zn2+ induces a strong attenuation of Co2+-related signals in ultraviolet-visible (UV-vis) extinction spectra; nevertheless, a good linear range for detecting 1–6 mg/L Co2+ in 50 g/L Zn2+ solution is still acquired. The strong anti-interference toward other metal ions and the mechanism understanding for trace Co2+ detection in such a high-concentration Zn2+ solution are also revealed by systematic analysis techniques. The results extend the AgNPs as colorimetric sensors to industrial solutions, providing a new strategy for detecting trace-metal ions in industrial plants. [ABSTRACT FROM AUTHOR]

An efficient and controllable process for separating copper and cadmium was required to be developed due to the high cost of the long separation process of copper cadmium slag generated from the zinc smelting process. Therefore, a new process for the application and deep separation of copper and cadmium was developed by combining the Circulating Flow Electric (CFE) cadmium cement method and the 2-hydroxy-5-nonyl formaldehyde oxime (M5640) copper extract method. The process firstly removed copper ions utilizing M5640 and obtained a primary purification solution, followed by CFE method to extract cadmium in depth. The effects of extractant volume fraction, pH, Oil phase/Aqueous phase (O/A) ratio and reaction time on the removal of copper ions were investigated. The results showed that the removal of copper was above 97%, while the removal of zinc and cadmium was below 1.6%, respectively, proved that the selectivity of M5640 for copper was significantly higher than that for metals such as cadmium and zinc. The characterization results indicate that the oxygen on the hydroxyl group and the nitrogen on the oxime group co-ligated with the copper ions and subsequently formed chelated extracts. That was the mechanism of the copper ion purification by M5640. Furthermore, the extraction of high purity cadmium was carried out in the extraction residual liquid. A novel method of cadmium removal enhanced by coupling an electric field with a circulating flow field was developed and applied to the cement cadmium from sulfate solutions. The optimal process conditions of the method were explored, which were further fitted into statistical equations and optimized by response surface analysis. Since the fitted theoretical results were close to the experimental results, the optimization was considered as effective. The optimized experimental parameters were 6.23 mL/s of flow rate, 48.14 mA/cm2 of current density, 2.25 of pH, and 0.93 of anode/cathode area ratio, respectively. Next, the extraction electrical efficiency, purity and its weight distribution in the cell of cadmium sponge under different flow fields were calculated and measured. The results were analyzed to prove the existence of an optimal interval for the distribution of cadmium under high-speed flow field. [ABSTRACT FROM AUTHOR]

Copyright of Multipurpose Utilization of Mineral Resources / Kuangchan Zonghe Liyong is the property of Multipurpose Utilization of Mineral Resources Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Purchasing decisions determine the purchasing cost, which is the largest section of the production cost of zinc smelting enterprise(ZSE). An excellent supplier recommendation is significant for ZSE to reduce the cost. However, during the supplier recommendation process, the nonlinear demand feature of purchasing department varies with the production environment, and there are wrong samples that can affect the supplier recommendation effect. To handle these problems, the recommendation strategy based on a multiple-layer perceptron adaptive online transfer learning algorithm(AOTLMLP) are proposed. In this method, the original prediction function is modified based on MLP nonlinear projective function and adaptive loss function, which enables the AOTLMLP algorithm to tackle the nonlinear classification problems and efficiently follow the demand change of purchasing department, thereby improving the result of the recommendation. The performance of the AOTLMO algorithm is evaluated through a common dataset and a purchasing dataset from a zinc smelter that generated by a supplier evaluation model. It can be assumed that AOTLMLP can ignore the influence of wrong samples and provide an effective recommendation confronting the characteristic of zinc ore purchasing. [ABSTRACT FROM AUTHOR]

Copyright of Mining & Metallurgy (10057854) is the property of Beijing Research Institute of Mining & Metallurgy Technology Group and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Hydrometallurgy of China is the property of Hydrometallurgy of China Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Purpose: Large stocks of many kinds of zinc smelting solid waste have been generated; moreover, the disposal process consumes high amounts of energy and takes low output rate of metal resources, which seriously endangers regional ecological environment and human health. The purpose of this study is to compare the environmental impact of the production process of zinc in the "traditional smelting mode" and the "solid waste synergism mode"; to further investigate the efficiency of material utilization, resource recovery, and carbon reduction in the two modes; and to provide expectations and suggestions for reducing environmental risks. Methods: This study focuses on a typical zinc smelting enterprise in China, with the help of SimaPro 9.0 software, to compare and analyze the differences in direct, indirect, and overall environmental impacts between the "traditional mode" and the "synergism mode," with a focus on the production and waste disposal processes. At the same time, the potential environmental burdens and carbon emission levels that could be reduced by solid waste co-processing are further investigated. Results and discussion: The results show that although the environmental burden of "the acid production from flue gas" is slightly higher in the synergism mode than the traditional mode, the environmental burden caused by all other processes is reduced by more than 20% and the energy consumption is reduced by 20.6–21.4% with the synergism mode. For the waste residue disposal process, the recovery rate of valuable components, such as Zn, Cd, and In, increased approximately 30% compared with the traditional mode, and the total environmental burden is reduced nearly onefold. In addition, the "concentrate + slag" smelting method has reduced zinc concentrate consumption per unit of zinc product by 26.7% and cut carbon emissions by 57.3%. Conclusions: Solid waste co-processing can effectively reduce the stockpiling of waste residues and perform secondary recovery of metal resources. Enhancing the solid waste collaborative utilization level can greatly reduce environmental risks and realize resource recycling for nonferrous industry. [ABSTRACT FROM AUTHOR]

[Display omitted] • The oxidative pressure leaching process for treating ZnS concentrate was modeled. • The process simulation-based life cycle assessment method was used. • The environmental impacts of the oxidative pressure leaching process was studied. • Zn, Cd, Co, Ga, and Ge production exhibited lower environmental impacts. • Recommendations for the process to sustainable zinc production were given. Considering the increasing environmental consciousness and the imperative for sustainable development, conventional zinc smelting operations employing the roast-leaching-electrowinning process face growing environmental pressures. Consequently, the oxidative pressure leaching process has emerged as an alternative processing route. This study focuses on recovery of major metals from ZnS concentrate, building a comprehensive model to simulate the oxidative pressure leaching process. The process model built demonstrated that zinc, sulfur, indium, gallium, cadmium, cobalt, germanium, and copper could be recovered effectively, the main chemical inputs being sulfuric acid, oxygen, and lime, while zinc electrowinning constituting over 90 % of the total electricity consumption. The results were used to compile a life cycle inventory, culminating in a gate-to-gate assessment of the environmental impacts of the process. The global warming potential for the treatment of 1 t of ZnS concentrate is approximately 2,000 kg CO 2 eq. The primary environmental impacts in the process are from chemical inputs and electricity consumption. Based on these findings, recommendations for sustainable production practices are proposed. These include systematic recovery and reuse of electrolytic off-gas and roasting heat, greater utilization of renewable energy, enhanced iron removal processes, and exploration of alternative chemicals for Ga and Ge recovery. [ABSTRACT FROM AUTHOR]

The zinc smelting solution purification process regulates the oxidation-reduction reactions (characterized by the oxidation-reduction potential (ORP)) by controlling the amount of zinc powder added to remove the impurity ions. In order to ensure the optimal operation of the process, the target key technical indicators should be converted into the optimal setpoint of controlled variables (that is, ORP). Based on the mechanism knowledge, fuzzy rules, and preference-guided predictive optimization, a comprehensive setting method for the optimal setpoint of controlled variables under multi-variation inlet status is proposed. It includes a hybrid trend detection method for inlet status, a mechanism model under multiple operating modes, and a fuzzy correction method and a preference-guided predictive optimization method to deal with slight and violent fluctuations in the inlet status, respectively. The experimental results show that the proposed method can obtain the optimal setpoint of controlled variables and reduce zinc powder consumption by approximately 3.6%. • A comprehensive setting method for the optimal setpoint of controlled variables under multi-variation status is proposed. • A hybrid trend detection method is proposed to identify different inlet statuses of the solution purification process. • Based on the reaction kinetics and the reaction efficiency, a mechanism model under multiple operating modes is constructed. • An optimal setpoint correction method based on fuzzy rules is proposed to cope with slight changes in inlet status. • A preference-guided predictive optimization method is proposed to cope with violent changes or anomalies in inlet status. [ABSTRACT FROM AUTHOR]

• A method of selective microwave heating of mercury-containing solid waste was established. • The optimal process parameters and mercury metabolism kinetics of the mercury removal process were verified. • Microwave can reduce the activation energy of the reaction and thus increase the volatilization rate of mercury. During the production process of lead and zinc smelting, a highly hazardous solid waste is generated. This waste contains valuable metal resources such as mercury, selenium, and lead. Specifically, the waste contains high levels of mercury, making it a hazardous waste. Currently, the treatment processes for this mercury-containing solid waste have drawbacks, including the need for high temperatures and long heating times. A novel process using microwave external field enhancement for the removal of mercury was proposed. The study also determined the optimal process parameters and investigated the kinetics of mercury metabolism. The experimental results indicated that the mercury-containing group members were the main substances absorbing microwaves in the mercury-containing solid waste. In terms of optimal process parameters, a heating temperature of 600 °C, a reaction time of 30 min, an oxygen flow rate of 20 L/h, and a volatilization efficiency of mercury exceeding 99 % were achieved. The volatilization kinetics of mercury during heating of the mercury-containing solid waste followed a first-order reaction model. Furthermore, the activation energy for microwave mercury removal was found to be 6.06 kJ/mol lower than that for conventional mercury removal, with a value of 29.41 kJ/mol. This lower activation energy facilitated a higher mercury removal efficiency compared to conventional methods. The use of microwaves allows for the selective heating of the mercury-containing components in solid waste, resulting in an increased volatilization efficiency of mercury. By utilizing a microwave heating system, mercury is effectively recycled as high-mercury slag. This approach effectively addresses the environmental concerns associated with mercury-containing solid waste. [Display omitted] [ABSTRACT FROM AUTHOR]

The fusion of industrial artificial intelligence with the Industrial Internet of Things (IIoT) can attain a heightened level of process monitoring in modern manufacturing processes. In general, the state variables of industrial processes collected through the IIoT encompass not only continuous variables but also numerous discrete variables. Owing to potential coupling factors, these variables frequently exhibit strong correlations. However, most existing methods deal only with continuous variables, which results in breaking the integrity of the state information and being incompetent to extract the useful information carried by discrete variables. To effectively address the joint monitoring challenges of continuous and discrete variables under the IIoT framework, hybrid variable dictionary learning (HVDL) is proposed in this paper. Specifically, considering that the values of discrete variables are finite sets, a specific discrete dictionary is built for data reconstruction. Besides, in order to consider the correlation between continuous and discrete variables, the alignment of them in the time dimension is achieved by sharing labels. The HVDL method can judiciously learn data dictionaries to extract multifaceted valid features across diverse data types, free from prior assumptions on data distributions. Finally, extensive experiments are conducted to demonstrate the superiority of the proposed method, including a numerical simulation case, a closed-loop continuous stirred tank reactor benchmark, and a real zinc smelting roaster. Experimental results indicate that the proposed method can fully consider the correlation between continuous and discrete variables, thus it is conducive to identifying early anomalies and mismatch anomalies. [ABSTRACT FROM AUTHOR]

Arsenic-containing multi-metallic materials, are typical hazardous wastes generated in the process of tin recovery from zinc smelting leach slag, exhibit low resource utilization and pose a significant risk of environmental pollution. This research proposed a vacuum reduction roasting technique utilizing anthracite as the reducing agent to remove arsenic and reclaim tin from such materials, characterized by high arsenic levels (8∼wt%) and the presence of several valuable metals. The results indicated that the arsenate in these materials was transformed into As 2 O 3 , which has better volatility, while SnO 2 was converted to SnO and Sn. Moreover, under the optimal conditions of a roasting temperature of 750 °C, 10 % anthracite, and a roasting duration of 3 h, the arsenic removal efficiency reached 96.97 %, and the tin recovery rate was 84.48 %. Consequently, the arsenic concentration decreased to 0.53 %, and the tin concentration in the roasted product increased from 17.70 % to 31.41 %. The final product contained phases of arsenic and tin, including Sn, SnO 2 , and FeAs. Meanwhile, this study provides a promising solution for the green and efficient separation of tin and arsenic in typical arsenic-containing multi-metallic materials. • The evolution mechanisms of typical compositions Zn 3 (AsO 4) 2 , As 2 O 3 , As, SnO 2 , SnO, and Sn in arsenic-containing multi-metallic materials were investigated and discussed in detail. • Highly efficient arsenic removal (96.97 %) and green enrichment of tin in aresenic-containing multi-metallic materials. [ABSTRACT FROM AUTHOR]

BACKGROUND The determination of impurity elements in hydrometallurgical zinc sulfate solution is helpful to optimize the composition of electrolytes, reduce energy consumption, and accurately feed and improve the purity of smelting metal. Impurity elements in the wet zinc smelting process are usually determined by manual sampling. The sample needs to be diluted before the equipment analysis is performed due to high content of zinc and sulfuric acid, which is difficult to achieve automatic analysis. OBJECTIVES In order to determine the online analysis of impurity elements in the solution of zinc smelting process and meet the current requirements of the hydrometallurgical industry. METHODS An automatic industrial on-line filtration/dilution combined with inductively coupled plasma-optical emission spectrometry (ICP-OES) was used. By optimizing key parameters and selecting appropriate analysis lines, a method for the rapid determination of copper, cadmium, cobalt and iron in zinc smelting solution was developed. RESULTS The experimental results showed that the linear relationship of each element was good, the correlation coefficient was greater than 0.9998, the relative standard deviation was 0.72%-1.39% (n=6), and the spiked recovery was 95%-110%. CONCLUSIONS The factory on-line automatic analysis system can replace traditional manual sampling to achieve automatic analysis. The results of on-line analysis are compared with those of manual sampling in actual production, showing good consistency. This method can be used to fully achieve automatic analysis, simple operation, accurate and reliable results, and is suitable for the analysis of impurity elements in zinc smelting.

Zinc smelting high sulfur residues is a dangerous waste residue produced by the zinc oxygen pressure leaching process. Due to the complex mineral phase and the lack of in-depth research on process mineralogy, it is difficult to safely utilize and dispose of high sulfur residues. The domestic typical high sulfur residue was studied in detail by chemical analysis, X-ray diffraction, process mineralogy and other research methods. The results show that the main minerals in high sulfur residues are elemental sulfur, sphalerite, pyrite, as well as trace amounts of quartz, muscovite, zinc vitriol and iron vitriol, etc. The minerals such as sulfur, sphalerite and pyrite in high sulfur residues are intertwined and symbiotic with each other in various forms, and most of the minerals use elemental sulfur as the inlaid base. The particle size of elemental sulfur, sphalerite and pyrite in high sulfur residues is fine, mostly concentrated below 74 μm. Therefore, increasing the particle size of elemental sulfur and the dissociation degree between sulfur and other minerals are the keys to improving the comprehensive recovery of valuable elements in high sulfur residues. [ABSTRACT FROM AUTHOR]

Soil particle size could intensively impact the Cd adsorption in soils. The adsorption characteristics of Cd on miscellaneous fill (MF) and weathered slate (WS), collected from a zinc smelting site, were studied by batch experiments under conditions of different initial Cd concentrations and soil particle sizes. The results showed that the adsorption kinetics of Cd for soil particles from MF and WS were well fitted with the pseudo-first-order model, and the Cd adsorption isotherms well conformed to the Freundlich model. Soil particle size had an inconspicuous influence on adsorption rate, while the adsorption capacity decreased with particle size increase. The Cd adsorption on soil particles could be due to the exchange with Fe/Al, and -OH/C=O sites were the predominant adsorption sites. The MF may cause secondary pollution risk due to its low adsorption ability for Cd in smelting sites. [ABSTRACT FROM AUTHOR]

• THg, MeHg and IHg in paired hair and fingernail samples from two typical mining areas showed positive correlation. • Fingernail samples can be another useful biomarker in application of assessing human Hg exposure. • Hair plays a more important role than fingernails in the excretion of Hg from human body. Effective biomarkers are necessary to better understand the human mercury (Hg) exposure levels. However, mismatched biomarker sampling method causes extra uncertainty in assessing the risk of Hg exposure. To compare the differences between hair and fingernail, and further understand the excretion rates of methylmercury (MeHg) and inorganic mercury (IHg) via hair and fingernails, the total mercury (THg), MeHg, and IHg concentrations in paired hair and fingernail samples were investigated through paired samples collected from two typical mining areas, Wanshan mercury mine area (WMMA) and Hezhang zinc smelting area (HZSA). The positive correlation in THg, MeHg, and IHg concentrations (p <0.01) between hair and fingernail samples indicated that those two biomarkers can be corrected in application of assessing human Hg exposure. Compared to fingernails, the hair was suggested to be a more sensitive biomarker as the concentration of THg, MeHg and IHg were 2 ∼ 4 times higher than those in fingernails. Furthermore, the amounts of THg, MeHg, and IHg excreted via hair were 70 ∼ 226 times higher than that excreted via fingernails, and the hair plays a more important role than fingernails in the excretion of Hg from human bodies. Present study therefore provides some new insights to better understand the fate of human assimilated Hg. [Display omitted] [ABSTRACT FROM AUTHOR]

Indium (In) has vital applications in solar photovoltaic technology and light-emitting diodes. However, the resource for In production is low. Zinc smelting is an important source of In, but the average In recovery rate is only 20%. The annual economic loss due to the loss of In is as high as USD 199.7 million. In this study, a high-sulphur hot filter residue (HFR) was processed via sodium-hydroxide (NaOH) hydrothermal treatment (NAHT). By varying the amount of NaOH and using the dissolution exotherm of NaOH, sulphur element (S0) in HFR was transferred to a liquid phase. Thus, In and other precious metals originally wrapped in S0 were enriched in the slag phase (TLR). The In grade in TLR was as high as 1700 g/t, and the recovery rate was 99%. In addition, 10.94 g/t gold, 125.81 g/t silver, 15.18% zinc and 22.27% iron were incidentally recovered. The wastewater produced in the process showed better effects than industrial Na 2 S in flotation processes. Thus, NAHT is an effective green recovery technique for recovering In and other precious metals from HFR. Further, the recovered In can yield an annual revenue of USD 1,122,170 for the plant. Therefore, the treatment of HFR plays an important role in zinc hydrometallurgical smelting plants. Green process diagram for recovering indium and other precious metal resources from high-sulphur hot filter residue (HFR) by using NaOH hydrothermal (NAHT) treatment [Display omitted] • Indium and other precious metals in high-sulphur hot filter residue were recovered by NaOH hydrothermal treatment. • Indium content in TLR was as high as 1700 g/t, and the recovery rate was 99.07%. • Gold, silver, zinc and iron were accidentally recovered from HFR at a rate greater than 90%. • No waste was produced in the process. • The recovered indium can bring annual revenue of USD1,122,170. [ABSTRACT FROM AUTHOR]

The changes in the wetting angle between sulfur and the main minerals in high-sulfur residue were investigated, which reflected the degree of difficulty of association between sulfur and the different minerals under various conditions. Sphalerite, pyrite, gypsum, quartz, and muscovite were selected as the research objects. The experimental results indicated that the wetting angle between sulfur and the five minerals decreases gradually with an increase in the temperature and reaches a stable level at approximately 130°C. Increasing the contents of the additives and the oxygen partial pressure can promote the separation of sulfur and the five minerals. Adding sulfuric acid to the system is conducive to the separation of sulfur and muscovite but not to the separation of sulfur and the other four minerals. Finally, according to the experimental data and a similarity theory, criterion equations for the wetting angle between sulfur and the five minerals were deduced. [ABSTRACT FROM AUTHOR]

• A highly efficient reductive leaching process for zinc ferrite-based solid waste decomposition. • Highly efficient utilization ratio of zinc sulfide as a reductant. Zinc ferrite-based solid waste is a vital zinc and iron secondary source in view of the numerous zinc ferrite will be ineluctably produced and enters into slags or residues during zinc smelting process. In this study, a reductive leaching process with zinc sulfide powder was employed to decompose zinc ferrite from solid waste. The leaching efficiency of zinc and iron can reach 90.27 % and 81.96 %, respectively, while the process went to the 90th min at 90 ℃ under the conditions: sulfuric acid concentration of 500 g/L, liquid-to-solid ratio of 20 mL g−1, mass ratio of silver flotation tailings to zinc sulfide of 5/1, silver flotation tailings particle size of + 180–250 μm, rotary speed of 400 rpm. Then, this leaching process confirmed to shrinking core model and was conducted by surface chemical reaction after kinetics and thermodynamics investigations. Ultimately, according to various tested data, the corresponding reaction mechanism was speculated as: Fe3+ was reduced to Fe2+ by zinc sulfide and hydrogen sulfide which was the product of zinc sulfide with H+, resulting in potential reduction and H+ activity elevation, accelerating zinc dissolution eventually. Meanwhile, almost all zinc sulfide and hydrogen sulfide were oxidized to monomorphic sulfur by Fe3+ where the utilization ratio of zinc sulfide was 97.28 %. [ABSTRACT FROM AUTHOR]