Recovery Of Tin Research Articles

Tin separation and recovery using the successive conversion of the self-possessed sulfur from low-grade tin middling

Low-grade tin middlings generated from mineral processing of tin tailings are composed of high contents of arsenic and tin, which pose a huge threat to environmental safety if not properly disposed. An approach of arsenic and tin separation from it using a combined roasting process was proposed in this work. First with oxidizing roasting, FeAsS from the tin middling was decomposed to As4 (g) and oxidized to As4O6 (g), achieving the arsenic separation of 97.1%. More importantly, sulfur in FeAsS was oxidized to iron sulfate and retained in the residue, which could be used as curing reagent for tin separation in the followed self-sulfurization roasting. However, massive SO2 (g) generated from the decomposition of iron sulfate volatilized before it sulfurizing SnO2 in the roasting, causing a low tin recovery. CaO could convert iron sulfate to CaSO4, slow the release of SO2 (g) and insure a high S/Sn ratio in the roasting. Moreover, CaO decreased the residue sintering by converting FeS-FeO to Ca2Fe2O5, CaFeO2 and CaS. Tin recovery was promoted and could obtain 98.2%. This study provides a new technical route for the separation and recycle of arsenic and tin from a hazardous material of low-grade tin middling.

Selective Recovery of Tin from Electronic Waste Materials Completed with Carbothermic Reduction of Tin (IV) Oxide with Sodium Sulfite

A new approach for the thermal reduction of tin dioxide (SnO2) in the carbon/sodium sulfite (Na2SO3) system is demonstrated. The process of tin smelting was experimentally optimized by adjusting the smelting temperature and amounts of the chemical components used for the thermal reduction of SnO2. The numbers obtained are consistent with the thermodynamic characteristics of the system and molar fractions of reactants derived from the proposed mechanism of the SnO2 thermal reduction process. They reveal that the maximum yield of tin is obtained if masses of C, Na2SO3 and SnO2 are approximately in the ratio 1:2:3 and the temperature is set to 1050 °C. The key role in the suggested mechanism is the thermal decomposition of Na2SO3. It was deduced from the available experimental data that the produced sulfur dioxide undergoes carbothermic reduction to carbonyl sulfide—an intermediate product involved in the bulk reduction of SnO2. Replacing sodium sulfite with sodium sulfate, sodium sulfide and even elemental sulfur practically terminated the production of metallic tin. The kinetic analysis was focused on the determination of the reaction orders for the two crucial reactants involved in the smelting process.

Removal of arsenic and recovery of tin from arsenic-containing multi-metallic materials by vacuum reduction roasting

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 As2O3, which has better volatility, while SnO2 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, SnO2, 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.

Separation and Recovery of Tin from Waste Printed Circuit Boards

Separation and Recovery of Tin from Waste Printed Circuit Boards

An approach of cobalt recovery from waste copper converter slags using pig iron as capturing agent and simultaneous recovery of copper and tin

Massive amounts of waste copper converter slags have been produced from pyrometallurgical extraction of copper from copper concentrates, and the disposal of them in landfills creates serious environmental problems. However, this converter slag contains numerous valuable heavy metals, including copper, cobalt and tin etc. In this research, due to similar properties of iron and cobalt, pig iron with a low melting point was creatively used as capturing agent for cobalt recycling in a smelting reduction. The recovery of copper and tin was also studied. The phase transformation during reduction process was clarified by X-ray diffraction and Scanning electron microscope-energy dispersive spectrometer analyses. After the reduction performed at 1250 °C, the copper, cobalt and tin were recovered in a copper-cobalt-tin-iron alloy. The addition of pig iron improved cobalt yield, which was ascribed to the enrichment of cobalt in an iron–cobalt alloy phase. This decreased activity of the reduced cobalt and promoted reduction of cobalt oxide. As a result, the cobalt yield had a significant increase from 66.2% to 90.1% by adding 2% pig iron. Similarly, the copper also accelerated tin recovery through the formation of a copper–tin alloy. The copper and tin yields reached 94.4% and 95.0%, respectively. This work provided a high efficiency method to recover copper, cobalt and tin from waste copper converter slags.

Recovery of tin from tin-coated copper-clad steel wire scrap using surface sulfuration-vacuum volatilization

Tin-coated copper-clad steel wire scrap is a high value-added tin-coated waste derived from the production and replacement of electronic products. The existing methods for the treatment of tin-coated waste present shortcomings, such as a large amount of waste liquid treatment, high equipment anticorrosion costs and low tin recovery rate. In this work, pyrite is used as a sulfurizing agent, and under the condition of vacuum decomposition to produce sulfur vapor, sulfur vapor reacts with tin on the surface of CP wire scrap to form stannous sulfide. Stannous sulfide continues to volatilize under high vacuum temperature conditions, realizing the complete separation of tin and other metals. Under an FeS2 and Sn molar ratio of 1.8, reaction conditions of a temperature of 1323 K, holding time of 4 h, and pressure of 10 Pa, the direct yield of tin is 91.26%, and the purity of stannous sulfide is 98.12%. Clean and efficient recycling of tin plating on the surface of tin-coated copper-clad steel wire scrap was realized using this method, and the comprehensive utilization rate of secondary resources containing tin was enhanced.

Development of one-step process method to separate tin from tin-refining sulfur slag via vacuum sulfuration and volatilization

Sulfur slag is a dangerous solid waste generated during tin refining. To ensure environmental safety, sulfur slag must be treated. As a result, a novel one-step process method was proposed and developed for clean and efficient recovery of tin and copper from sulfur slag. The method was based on the thermal stability of pyrite to simultaneously sulfurize and volatilize tin, which greatly improved the reaction efficiency. The feasibility of the one-step separation of tin and copper was confirmed by theoretical calculations such as Gibbs free energy and saturated vapor pressure. The effects of temperature, pyrite dosage, system pressure, and holding time were experimentally studied. Finally, the volatile was stannous sulfide, and the residue was cuprous and ferrous sulfides. The optimal experimental conditions were as follows: the reaction temperature was 1273 K, the pyrite addition ratio was 40%, the system pressure was 10 Pa, and the holding time was 3 h. The direct recovery rates of tin, copper, and iron were 99.95, 99.77, and 99.57%, respectively. The removal rates of tin, copper, and iron were all above 99.8%. The vacuum sulfuration and volatilization method provides a novel process for the clean and effective cyclic treatment of tin-refining sulfur slag.

Eco-Friendly Electrowinning for Metals Recovery from Waste Electrical and Electronic Equipment (WEEE)

The amount of waste electrical and electronic equipment (WEEE) has been intensely increasing over the recent decades. In this view, the efficient recovery of metals from WEEE will allow a secure supply of raw materials and will contribute to a circular economy. Among many factors currently affecting the contribution of recycling, is the lack of suitable technologies for WEEE treatment in an environmentally friendly way. Current trends in eco-friendly technologies applied for gold, silver, copper, and tin recovery by electrowinning are reviewed in this paper. In addition, a case study on the perspectives of tin electrowinning has been evaluated. Tin can be present in rather high quantities in WEEE; moreover, its price is about three times higher than that for copper. The electrorecovery of tin has been carried out in cooperation with JSC “Elektronikos perdirbimo technologijos”. The eco-friendly process based on electrowinning from citric acid-containing leachates is elaborated. The citrate-based solutions have been chosen because citric acid is considered to be an environmentally friendly component. A high deposition rate and current efficiency have been achieved at a deposition potential −0.85 V at 60 °C. However, additional steps would be beneficial to diminish the interference of metals present in the scraps, such as Pb(II) and Cu(II), on tin electrorecovery.

Recovery of copper and tin from waste tinned copper wires by ultrasonic assisted chemical replacement

Recovery of copper and tin from waste tinned copper wires by ultrasonic assisted chemical replacement

Leaching behavior and process optimization of tin recovery from waste liquid crystal display under mechanical activation

Recycling Sn from waste liquid crystal display (LCD) is crucial to alleviate resource shortage and prevent environmental pollution. However, the disposal of waste LCD is a complex coupling process affected by multi-factors. The lack of mature harmless and resource-based treatment process restricts the development of industrialization. Therefore, an environmentally sound process focusing on resource recovery was proposed to recover Sn efficiently and remove toxic substances from waste LCD in this study. The reaction mechanism and leaching kinetics were discussed assisted by mechanical activation, and the statistical and mathematical method (Box-Behnken Design (BBD) model) was adopted to optimize the leaching process. The results showed that the mechanical activation could improve the physical and chemical properties of ITO glass. The essence of the leaching reaction mechanism was that the H+ in H2SO4 combined with O2− in the lattice of In2O3 to form OH−, resulting in Sn–O bond broking and Sn4+ entering the aqueous solution. Furthermore, the Zeta potential results showed that the Zeta potential of SiO2 particles less than 0.035 mm was close to zero near pH 2, resulting in agglomeration between SiO2 particles under the action of Coulomb force. The leaching kinetics was well expressed by the shrinking core model. The BBD model showed satisfactory correlation between the predicted and actual results, and the particle size was the most critical factor affecting the leaching efficiency. The maximum leaching efficiency was 87.6% which was obtained under the following optimal condition: 6 mol/L H2SO4, 108 min, 88 °C, and 0.035 mm ITO glass powder. Our findings demonstrated that the developed recovery process was both efficient and environmentally sound, which had the potential in the industrialization of waste LCD recycling system.

Separation and recovery of tin and copper from tin refining sulfur slag using a new process of airtight sulfuration – Vacuum distillation

Sulfur slag is a high-value hazardous waste produced during the refining process of crude tin. To reduce the emission of wastewater, harmful gas, and hazardous residue, a theoretical and experimental investigation was carried out to develop a new process for converting metal to metal sulfide that utilizes physical differences (saturated vapor pressure) for separation. Here, a sulfur slag processing approach based on airtight sulfuration-vacuum distillation is proposed. In this paper, the Gibbs free energies of the sulfuration reaction of tin and cuprous sulfide and the decomposition reaction of copper sulfide are calculated, the saturated vapor pressure of each substance is analyzed, and the composition of the products is predicted. By adding sulfur to sulfur slag, the composition of the substances in the slag was regulated, and efficient separation of tin and copper was achieved based on the difference in volatility of the compounds. The optimum sulfur addition amount, sulfuration temperature and time, and volatilization temperature and time were investigated using airtight sulfuration and vacuum distillation experiments. The results show that tin and cuprous sulfide were thoroughly sulfurated when 20 g sulfur was added, the airtight sulfuration temperature was 573 K, and the holding time was 4 h. Stannous sulfide volatilizes violently above 941 K and volatilizes completely at 1273 K. The purities of stannous sulfide and cuprous sulfide obtained by the airtight sulfuration-vacuum distillation experiment were 99.02% and 99.30%, respectively. The direct recovery rates of tin and copper were 99.93% and 99.91%, respectively. The removal rate of copper in the volatiles was 99.84%, and the removal rate of tin in the residue was 99.96%. The method thoroughly separated tin and copper from sulfur slag, significantly reducing the environmental and economic costs compared to those of the traditional process.

Optimization, Kinetic Studies of Tin Leaching from Waste Printed Circuit Boards and Selective Tin Recovery from Its Pregnant Solution

To protect natural resources and avoid environmental pollution, an effective method is proposed to recover tin (Sn) from waste printed circuit boards (WPCBs). In order to realize the efficient recovery of Sn, it is necessary to study the effects of experimental parameters on Sn leaching and understand the leaching kinetics of leaching processes. The statistical and mathematical technique (response surface methodology (RSM)) was used to study the effects of interactions of experimental parameters on the leaching rate and optimize experimental parameters. Moreover, a comprehensive understanding of the leaching kinetics of Sn in hydrochloric acid solution was obtained. The results show that the maximum Sn leaching rate was 97.6% which was obtained under the following optimal condition: 74.1 °C, 4.94 mol/L HCl, 495.5 rpm, and a solid–liquid ratio of 0.08 g/mL. The leaching mechanism of Sn was controlled by mixed control reaction with an activation energy of 20.3 kJ/mol. A macroscopic kinetic equation was also established, which summarizes the relationships between the experimental parameters and the leaching rates and can predict leaching results. The Sn in pregnant leach solution was recovered as stannic oxide (SnO2) by precipitation-high temperature calcining technique. In this paper, a complete flowsheet for Sn recovery from WPCBs was developed.

Evaluation of Efficiency of Using Mechanized Processing Techniques to Recover Tin and Tantalum in Gatsibo, Eastern Province, Rwanda

Rwanda is known to be among the top producers of tin and tantalum, despite having low recovery and grades. This study was carried out to evaluate the efficiency of using mechanized methods to increase the recovery rate and grades of tin and tantalum mined in Gatsibo, Eastern Province, Rwanda, since the general separation techniques used are artisanal. The minerals in those mines include cassiterite (SnO2) and colombite–tantalite ((Fe,Mn)(Ta,Nb)2O5), with impurities such as Al2O3, Fe2O3, MnO, MgO, Cao, Na2O, K2O, TiO2, and P2O5. A combination of gravity separation techniques, including shaking tables and magnetic separation, were used as the mechanized processing techniques. The results were compared to the results obtained by artisanal processing techniques. The proposed mechanized techniques were found to increase the efficiency of tin and tantalum recovery from 60.75% to 81.85% and from 22.9% to 48.57%, respectively, and the grades of the tin and tantalum increased to 63.75% and 35.7%, respectively. Based on these results, the proposed mechanized processing techniques and the recycling of waste from artisanal processing techniques are highly recommended.

Selective extraction and recovery of tin from hazardous zinc-leaching residue by oxalic acid/sulfuric acid mixture leaching and hydrolytic precipitation

Zinc-leaching residue (ZLR) with 0.46% Sn and 54% Pb brings potential threats to environment but is worthy to recover valuable metals. Reduction of Sn(IV) to Sn(II) is critical for tin extraction. In this work, selective extraction and recovery of tin from ZLR via oxalic acid/sulfuric acid leaching and hydrolytic precipitation was proposed. Various reductants were attempted, and the oxalic acid shows superior tin leaching efficiency. The effects of reduction leaching and hydrolysis parameters on the separation of Sn and Pb were systematically investigated. After leaching by 24 g/L oxalic acid in 0.50 mol/L H2SO4 at 60 °C for 30 min with L/S ratio of 10 mL/g and stirring speed of 400 r/min, 90.5% Sn is leached into the solution, and 99.8% Pb is simultaneously concentrated in the leaching residue. In the hydrolysis process, tin sediment with recovery of 93.8% and content of 46.4% was obtained. The as-prepared tin and lead products can directly act as concentrates for the tin and lead smelting. The oxalic acid reduction leaching mechanism of tin was also discussed. Based on the reduction leaching behaviors of tin from ZLR, the possible Sn leaching enhancement via oxalic acid addition in the existing industrial zinc-leaching process was proposed in this work.

Flotation extraction of tin from tailings of sulfide-tin ore dressing using thermomorphic polymer

The possibility of using a thermomorphic polymer with a phosphine group as a collecting reagent for the selective concentration of tin during flotation enrichment of sulfide-tin tails was first investigated in the work. A detailed description of the experimental scheme of flotation concentration of sulfide-tin ore tailings and the reagent mode are given. The main mineral of tin is cassiterite, highly brittle and inclined to sludging, which leads to large losses of tin with tails; the granulometric composition of the initial tails of the Solnechnyi mining and processing plant has showed that 50% of the sample is represented by size grade of –0.04 mm. The output of a slimy product of –20 μm is 20% with a tin content of 0.46% (according to chemical analysis). This product is one of the sources of tin losses (up to 33.5%) in the flotation concentration process and requires additional technological solutions. It has been shown that the use of selective concentration of the +20 μm class using a thermomorphic polymer (TMPF) for flotation of tin ores allows not only to reduce the loss of tin with thin classes, but also significantly increase the flotation rate of cassiterite and technological parameters when beneficiating mature tailings of tin-sulfide ore processing. The main tin flotation using TMPF results in obtaining a rough tin concentrate I with a content of 0.55% Sn and extracting 49% of the operation. Rough tin concentrate II with a content of 0.38% Sn and 42% recovery was obtained by reextraction using TMPF. The total recovery of tin in the combined rough tin concentrate amounted to 90.71% of the operation. Subsequent purification of the obtained concentrate and gravity enrichment on the table concentrator will make it possible to obtain the concentrates richer in tin content required for their further processing. Further research will be aimed at developing scientifically based technological solutions to improve the quality of rough tin concentrate and extracting tin from the sludge product –0.02 microns using new reagent compositions. The study has been implemented at the expense of the Russian Science Foundation grant (project No. 17-17-01292).

The Recovery of Metallic Tin from an Industrial Tin-Bearing By-Product Containing Na2SO4 by Reduction Smelting Process

Tin was recovered in metal from an industrial tin-bearing byproduct containing Na2SO4 by carbothermic reduction smelting, and the effects of basicity (Na2O/SiO2), temperature, and reaction time on the recovery of tin were studied. Na2SO4 was reduced by carbon and formed into sodium silicate slag (Na2O–SiO2) in the presence of SiO2. Tin content in slag decreased with the increase of Na2O/SiO2 ratio in slag, temperature, and reaction time, but the recovery of tin was affected by volatilization of tin in high temperature and high silica region of basicity. In this study, the maximum recovery rate of tin was 94.8% at the experimental condition of 1200 °C, 2 h, and 0.55 of Na2O/SiO2 ratio. The major impurities in produced metal were Bi, Pb, Cu, Fe, and most of Bi, Pb, Cu were distributed to the metal phase, but the distribution of Fe was closely related to basicity.

Electrochemical dissolution and recovery of tin from printed circuit board in methane–sulfonic acid solution

Current industrial Sn stripping processes from raw printed circuit board (PCB) are carried out typically in nitrate system and inevitably produce low-concentration NOX gas pollutant and high-concentration nitrate wastewater. This study proposes a novel and high-efficient Sn electrochemical stripping and recovery method from PCBs in methane–sulfonic acid (MSA) solution. A PCB covered with Sn was used as the anode, and Sn was removed by one-step method and deposited on the cathode in the electrolysis process. This work also investigated the influences of various electrolysis conditions on the change of current efficiency, electric power consumption, and PCB surface morphology. The optimal conditions were 40 °C, 60 g/L Sn2+, 100 g/L MSA, 60 mm inter-electrode spacing, and 200 A/m2 current density for Sn dissolution and extraction. About 85% of Sn was removed from the anodic PCB and subsequently electrodeposited at the cathode under the most suitable conditions. The electric power consumption was 63 kWh/t-Sn, and the electrolyte had a long lifetime. Moreover, the copper layer was not corroded, and no Sn remained on the surface of the anodic PCB after immersion in the picking solution. This novel technique provides an efficient alternative for Sn removal and recovery from PCB and will promote resource recycling and environment protection in raw PCB manufacturing industry.

Recovery of Tin as Tin oxide nanoparticles from waste printed circuit boards for photocatalytic dye degradation

Recovery of Tin as Tin oxide nanoparticles from waste printed circuit boards for photocatalytic dye degradation

Ammonia chloride assisted air-chlorination recovery of tin from pyrometallurgical slag of spent lead-acid battery

Tin-containing slag from pyrometallurgical recovery process of spent lead-acid battery is a valuable secondary Sn resource. However, the low content of Sn (~4 wt%) in this slag with complex impurities (Fe, Al, Pb, Zn, and Cu, etc.) makes it challenging for efficient tin separation. In this study, a low-temperature chlorinating process is proposed for tin recovery from the tin-containing slag by using ammonium chloride as the chlorinating reagent. Under the optimized chlorinating conditions, tin volatilization ratios of above 96% under both air and vacuum atmospheres could be achieved. However, the discrepancy between the temperatures of tin chlorinating and impurity metal chlorinating is more dramatic under the air atmosphere than that under vacuum, which facilitates the separation of impurities. Meanwhile, the decomposition rate of NH4Cl in air is much lower than that under vacuum atmosphere, resulting in less consumption of NH4Cl. The obtained chlorinated condensation product in air is subjected to a subsequent water leaching-alkali smelting-leaching-crystallization process to effectively separate Fe impurity and obtain the final sodium stannate product with a total tin recovery ratio of 94%. This study provides a promising strategy for the recovery of tin, and significant environmental benefit could be generated simultaneously with solid waste recycling.

Tin recovery from a low-grade tin middling with high Si content and low Fe content by reduction—sulfurization roasting with anthracite coal

A new method for separating and recovering tin from a low-grade tin middling with high Si content and low Fe content by roasting with anthracite coal was researched by studying the reaction mechanism and performing an industrial test, in which the Sn was sulfurized into SnS(g) and then collected using a dust collector. The Fe-Sn alloy may be formed at roasting temperatures above 950°C, and like the roasting temperature increases, the Sn content and Sn activity in this Fe-Sn alloy decrease. Also, more FeS can be formed at higher temperatures and then the formation of FeO-FeS with a low melting point is promoted, which results in more serious sintering of this low-grade tin middling. And from the thermodynamics and kinetics points of view, the volatilization of the Sn decreases at extremely high roasting temperatures. The results of the industrial test carried out in a coal-fired rotary kiln show that the Sn volatilization rate reaches 89.7% and the Sn is concentrated in the collected dust at a high level, indicating that the Sn can be effectively extracted and recovered from the low-grade tin middling with a high Si content and low Fe content through a reduction—sulfurization roasting process.