Leaching Of Tin Research Articles

Separation of indium and tin from ITO powders with short-chain dicarboxylic acid-ChCl deep eutectic solvents: Indium tin leaching and splitting mechanism

The substitution of corrosive mineral acids with green deep eutectic solvents (DESs) for extracting rare and precious metals from discarded electronic devices has a sustained appeal for developing clean hydrometallurgical processes. However, the dissolution mechanism of DESs on specific metals still requires an exhaustive understanding. In this work, short-chain dicarboxylic acid-choline chloride DESs were used to dissolve indium tin oxide (ITO) to achieve the separation of indium and tin. Kinetic and thermodynamic studies have shown that the leaching of indium and tin was considered a mixed control of diffusion and chemical reaction, with low activation energies (Ea(In) = 39.93 kJ/mol, Ea(Sn) = 39.52 kJ/mol). The electrospray ionization mass spectrometry (ESI-MS) analysis of the leaching solution and molecular orbital calculations revealed that tin was leached in the main form of [Sn4+(OH−)3(H2O)]+ cation as well as slight [Sn4+MA2−(Cl−)3]− anion, while the dominant ions of indium were [In3+(Cl−)4]− ligand as well as small amounts of [In3+MAH−(Cl−)4]2−, [In3+(MA2−)3]3− and [In3+MA2−(Cl−)2]−. The tin-containing species in the leaching solution can be completely precipitated in the form of cassiterite SnO2 through water dilution and hydrothermal treatment, in which amorphous indium-containing substances were mixed. Most of the indium was retained in the form of [In3+(Cl−)4]− in the liquid. After adjusting the pH of the solution, over 99% of the indium precipitated out as In(OH)3, and after calcination at 600 °C in air for 1 hour, In2O3 was obtained. This study unveiled the leaching mechanism of short-chain dicarboxylic acid-choline chloride DESs on ITO powders. It developed a green, simple, and mild process for potentially recovering ITO-based materials.

Properties of SrCe0.95M0.05O3 (M = La, Pr, Y, Sn) thermal barrier materials

The lightly doped strontium cerates SrCe0.95M0.05O3, where М = Pr, Y, La, and Sn, are shown to maintain an invariable Pnma structure at heating in the air up to 1773 K. The decrease in the size of the doping atoms is found to be beneficial for tuning up the thermal expansion coefficient, reducing the average grain size and sinterability of ceramic samples. The doping with large atoms is accompanied by a deterioration in corrosion resistance in the melt of CMAS because of the formation of aluminates and silicates. The tin–doped derivative is not sufficiently stable because of the leaching of tin from the structure. The penetration of the CMAS melt into surface cracks and pores facilitates exfoliation of flakes from the surface, thus contributing to the degradation of cerite ceramics. The combination of small grain size and porosity, optimized thermal expansion, chemical robustness in the melts of CMAS, and high hardness distinguishes SrCe0.95Y0.05O3 as a promising thermal barrier coating material.

Particle Image Velocimetry Method for Prediction Hydrodynamic Conditions during Leaching Process on the Basis of Sn-NaOH System.

In leaching processes controlled by diffusion and convectional transport of mass, the hydrodynamic structure formed in the reactor’s working volume is an additional factor affecting the process. This research work presents results related to hydrodynamic structures developing in batch reactors, different in shape, recorded by means of the particle image velocimetry (PIV) method. The movement of the distilled water and leaching solution was analyzed during investigations. Next, the system hydrodynamics and the process of tin leaching were analyzed. Finally, the leaching is affected by the reactor geometry and the hydrodynamic structure developed in its working volume, especially when a convectional or diffusion mass transport decides the process efficiency.

The Hydrolytic Stability and Degradation Mechanism of a Hierarchically Porous Metal Alkylphosphonate Framework.

To aid the design of a hierarchically porous unconventional metal-phosphonate framework (HP-UMPF) for practical radioanalytical separation, a systematic investigation of the hydrolytic stability of bulk phase against acidic corrosion has been carried out for an archetypical HP-UMPF. Bulk dissolution results suggest that aqueous acidity has a more paramount effect on incongruent leaching than the temperature, and the kinetic stability reaches equilibrium by way of an accumulation of a partial leached species on the corrosion conduits. A variation of particle morphology, hierarchical porosity and backbone composition upon corrosion reveals that they are hydrolytically resilient without suffering any great degradation of porous texture, although large aggregates crack into sporadic fractures while the nucleophilic attack of inorganic layers cause the leaching of tin and phosphorus. The remaining selectivity of these HP-UMPFs is dictated by a balance between the elimination of free phosphonate and the exposure of confined phosphonates, thus allowing a real-time tailor of radionuclide sequestration. Moreover, a plausible degradation mechanism has been proposed for the triple progressive dissolution of three-level hierarchical porous structures to elucidate resultant reactivity. These HP-UMPFs are compared with benchmark metal-organic frameworks (MOFs) to obtain a rough grading of hydrolytic stability and two feasible approaches are suggested for enhancing their hydrolytic stability that are intended for real-life separation protocols.

PRELIMINARY STUDIES ON HYDROMETALLURGICAL TIN RECOVERY FROM WASTE OF TIN STRIPPING OF COPPER WIRES

This paper presents the results of tin leaching and electrowinning from SnO 2 waste originating from the industrial process of tin stripping of copper wires. The sludge was leached by acids (sulfuric, hydrochloric, tartaric, oxalic) and sodium hydroxide at various temperatures (40–80°C). The highest efficiency of tin leaching (12–18%) was obtained in an oxalic solution, while the lowest effectiveness (0.2–0.5%) was found for sulfuric acid. Tin leaching was accompanied by a transfer of copper residues to the solution. The electrowinning stage was realized under potentiostatic and galvanostatic conditions using oxalate solutions. Cyclic voltammetry was applied to select the potentials for the selective deposition of metals.

Recovery of Copper and Tin from Used Printed Circuit Boards

This work focuses on possibilities to recover tin and copper by hydrometallurgical processes from printed circuit boards (PCBs) of discarded personal computers after thermal treatment. For experimental work crushed and sorted printed circuit boards with various granularity /-8 +0 mm, -8 +3 mm, -3 +0 mm/ were used. They were exposed to thermal treatment at temperatures 300 °C, 500 °C, 700 °C and 900 °C before leaching for 15, 30 and 60 minutes. The two thermal treatments were studied: in air flow, i.e. burning, and pyrolysis (without air flow). For leaching experiments 1M solution of HCl at 80 °C was used. Under the mentioned conditions both samples, the thermally treated sample of PCB as well as the original untreated printed circuit board, were leached with the aim to compare the experimental results. Weight losses during burning accounted for 5 to 35 %, while pyrolysis caused weight losses from 10 to 30 %, depending on the thermal treatment temperature. The higher the burning temperature, the higher the extraction of copper into the solution with up to 98%.However, extraction of copper from non-burned samples does not exceeded 6 %. An opposite effect has been observed during leaching of tin, where the highest extraction was reached using thermally untreated samples, and extraction decreased with an increasing burning temperature. With increasing pyrolysis temperature a higher extraction level was observed during leaching of copper and tin into the solution. The maximal extraction was reached with the leaching of thermally untreated samples, namely 6 % for copper and about 68 % for tin whereas the extraction of copper and tin achieved with thermally treated samples was 63 % and 98 %, respectively.

Electrolytic Recovery of Tin from Printed Circuit Boards (PCBs) Disassembled from Waste Liquid Crystal Displays (LCDs): Selection of H<sub>2</sub>SiF<sub>6</sub> + H<sub>2</sub>SO<sub>4</sub> + H<sub>2</sub>O<sub>2</sub> Leaching Solution over Two-stage Leaching in HNO<sub>3</sub> and HCl

Waste PCBs (Printed Circuit Boards) from LCDs (Liquid Crystal Displays) contain valuable raw materials, Sn, Cu, and other noble metals. Among these, high purity tin was obtained by electro-winning after appropriate acid leaching of tin. For this, leaching and electro-winning process parameters were optimized for solution stability, dissolution and electrolytic efficiency. Two aqueous procedures were developed and tested for electro-winning at mass-production capable basis: (1) HCl leaching after preliminary HNO3 dissolution was quite effective in leaching high proportion of Sn as analyzed by ICP (Inductively Coupled Plasma) method. (2) Direct one-step leaching in H2SiF6 + H2SO4 + H2O2 was also tested and the solution was finally selected as electrolytes in electro-winning due to massproduction capability. The most efficient recovery of tin was observed after 7h electro-winning in aqueous H2SiF5 + H2SO4 + H2O2 maintained at 40oC: 96%-pure tin was obtained with 93.2% recovery rate. Keywords: Electronic waste, LCD, leaching solution, PCB, recovery, Tin.

A continuous process for glyoxal valorisation using tailored Lewis-acid zeolite catalysts

The aqueous-phase heterogeneously catalysed isomerisation of bio-oil derived glyoxal is herein introduced as a novel route for the sustainable production of glycolic acid. While commercial ultra-stable Y zeolites displayed only moderate performance, their evaluation enabled us to highlight the crucial role of Lewis acidity in the reaction. Gallium incorporation into these zeolites boosted the glycolic acid yield, although the best catalytic results were obtained over tin-containing MFI-type zeolites, reaching 91% yield of the desired product at full conversion. These materials comprised hydrothermally-synthesised Sn-MFI as well as a novel catalyst obtained by the introduction of tin into silicalite-1 by means of a simpler and more scalable method, i.e. alkaline-assisted metallation. In-depth spectroscopic characterisation of these systems uncovered a substantial similarity of the tin centres obtained by the top-down and bottom-up synthetic approaches. NMR spectroscopic studies gave evidence that the reaction follows a 1,2-hydride shift mechanism solely catalysed by Lewis-acid sites. The Sn-MFI analogue could be reused in 5 cycles without the need for intermediate calcination, did not evidence any tin leaching, and demonstrated suitability for utilisation under continuous-flow operation. The tin-based zeolites exhibited remarkable performance also in alcoholic solvents, leading to the one-pot production of relevant alkyl glycolates.

Electrolytic Recovery of Tin from Waste Lead Frames: Use of Aqueous HCl Leaching Solution as Electrolyte

Abstract Lead frames are generated in large quantities by modern semiconductor packaging industry and they contain significant concentrations of valuable tin, nickel, and copper. For electrowinning of tin from waste lead frames, hydrochloric acid leaching of tin is quite advantageous, but solution stability, electrolytic efficiency and deposit morphology should be optimized before commercialization. HCl electrolyte was diluted (distilled water: HCl = 350:150) for electrowinning of waste lead frames at 40 °C with 0.2 A/cm2 and Ti-Ir cathode. After 4 h electrowinning, 99% pure Sn with 99.1% recovery rate was produced. Therefore, aqueous HCl electrolyte was quite effective for electrowinning of Sn leaching solution, and a higher recovery rate of purer Sn within shorter electrowinning time was obtained.

Experimental Investigation of Indium Extraction by Sulfuric Acid Precure Pressure-Atmospheriation Leaching from Tin Dust

Sulfuric Acid precure Pressure-atmospheriation leaching process from tin dust was studied. The factors had been investigated,which effects indium leaching rate,the factors are :the sulfuric acid initial temperature, curing time of heat, acid dosage, leaching reaction time, leaching temperature, the liquid-solid ratio and so on.The results show that the indium, zinc and tin leaching rate can be 96.68%, 97.70% and 0.52%,while pressure-atmospheriation leaching is carried out under the initial temperature 140°C,sulfuric acid, the time of heat aging 40 min, acid dosage and tin of tobacco smoke mass ratio0.7:1, leaching time 1.5h, leaching temperature 90°C,and the liquid-solid ratio 4:1 conditions.

Hydrometallurgical treatment of used printed circuit boards after thermal treatment

The hydrometallurgical route of copper and tin extraction from printed circuit boards (PCB) of used personal computers after thermal pretreatment is discussed. The PCB fractions crushed and sorted into −8 + 0, −8 + 3 and −3 + 0 mm were used for the experiments. The samples were thermally pretreated at temperatures of 300, 500, 700 and 900 °C during 15, 30 and 60 min with the presence of air (burning) before the leaching process. The leaching solution of 1 M HCl and temperature of 80 °C was used for the leaching. The original as well as thermally pretreated samples were leached under these conditions. The weight losses within the range from 5% to 35% were achieved by burning depending on the burning temperature. The increase of burning temperature causes the copper extraction into solution up to 98%, while copper extraction into solution from non-burned samples was up to 6%. The opposite effect was observed in the case of the tin leaching, where the highest extraction was achieved when the original sample was leached. The increase of the burning temperature caused the lowering of the copper extraction.

Catalytic properties of cross‐linked polystyrene grafted diorganotins in a model transesterification and the ring‐opening polymerization of ε‐caprolactone

AbstractThe catalytic properties of cross‐linked polystyrene grafted diorganotins of the types [PH](1−t)[P(CH2)11Sn‐n‐BuCl2]t and [PH](1−t){[P(CH2)11Sn‐n‐BuCl]2O}t/2, in which [PH] represents the monomeric unit of the cross‐linked polystyrene matrix and t is the degree of functionalization, were compared. The grafted chlorodistannoxane catalyst was completely characterized by elemental analysis, IR and Raman, 119Sn high‐resolution magic angle spinning (hr‐MAS) NMR and 117Sn CP‐MAS NMR spectroscopy. In spite of the spatial constraints and the potential steric demand resulting from cross‐linking, the grafted C11 chlorodistannoxane exhibited the same dimeric ladder complex arrangement as its nongrafted n‐butyl analog in the solid state and in solution. Moreover, 119Sn hr‐MAS NMR and 117Sn CP‐MAS NMR spectroscopy appeared to be complementary techniques for the assessment of the tin(IV) functionality of the grafted tetraalkyldichlorodistannoxane. The catalytic activity of the compounds was assessed in a model reaction, the transesterification reaction of ethyl acetate and n‐octanol, as well as in the ring‐opening polymerization (ROP) of ε‐caprolactone. Residual tin trace analysis was performed on the acquired reaction products. Whereas tin contents of the order of 20 ppm were found in the reaction products of the transesterification, tin leaching values were overall higher for the ROP, being less unfavorable, however, for the distannoxane ( ± 70 ppm) than for the dialkyltin dichloride ( ± 290 ppm). Quantitative liquid 1H NMR was applied to assess the conversions in both reactions, but also to determine various molecular parameters of the synthesized poly‐caprolactones. Furthermore, size exclusion chromatography was used to determine their polydispersity index. It was also demonstrated that 1H and 119Sn hr‐MAS NMR enable the chemical integrity and recycling ability of the catalyst to be assessed. Copyright © 2007 John Wiley & Sons, Ltd.

Synthesis and characterization of new polystyrenes containing tributyltin moieties linked to the aromatic ring through a methylenic spacer

AbstractNovel polymeric derivatives bearing tributyltin carboxylate moieties in the side chain were synthesized. The coordination at tin in solution and in the solid state was investigated by both Sn‐NMR and FT‐IR: the metal atom appears completely tetracoordinated in chloroform solution, while in the solid state all polymeric products exhibit both tetra‐ and pentacoordination at tin, the latter increasing with the amount of tin containing units. No evidence of tin leaching by hydrolysis of the organometallic ester was observed for these materials. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5372–5383, 2004

Influence of the support structure on the activity, stability, and metal leaching of a polymer-supported organotin chloride catalyst

Polymer-supported organotin chlorides have been synthesized by suspension copolymerization of organotin-functionalized styrenic monomers using a precipitating porogen. Their activities as reducing catalysts have been evaluated in the reduction of bromoadamantane by sodium borohydride. The influence of the length of the spacer arm between the tin atom and the polymer backbone on the activity and the tin leaching of the supported catalyst have been studied. The nature of the alkyl groups (butyl or phenyl) attached on the tin atom plays an important role on the stability toward successive reuse of the supported catalyst. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 1297–1308, 2001

Preparation and reactivity of a non-styrenic polymer-supported organotin chloride catalyst

A new type of macroporous polymer-supported organotin hydride has been prepared by suspension copolymerisation of an allyl ether monomer bearing an organotin moiety with N-phenylmaleimide and 1,1′-(methylenedi-4,1-phenylene)bismaleimide. Several resins were synthesised using different ratios of toluene–N-methylformanilide as the porogen. The swelling characteristics of the resins in different solvents and their specific surface areas were estimated. The organotin chloride-functionalised beads obtained showed good activity and good stability to reduction of bromoadamantane by sodium borohydride. Tin leaching during successive reuses was estimated.

Removal of tin from metal-containing industrial dusts

The separation of tin and other base metals from low-grade metal-containing industrial dusts was investigated using hydrometallurgical operations. Selective leaching of tin could be obtained with oxalic acid solution. Recovery of Sn, Zn, Cu, Pb and Fe from the leach liquor was investigated by solvent extraction with several commercial reagents.

Improved method for detection of organotins in food simulants

AbstractAn improved method for detection of organotin compounds in fatty food‐simulants has been developed. It offers improved sensitivity and specificity over complexation‐colorimetric and other methods. This method has been used to test for leaching of tin from PVC bottles stabilized with methyltin stabilizers. The results of this testing at various temperatures demonstrated safe levels for consumers.

Tin for organic synthesis, part 9: Preparation and investigation of a polystyrene-based organotin hydride as a versatile multiple-use reagent in organic synthesis. Part I: the functionalization approach

A series of poly( p-vinylstyrene)s was prepared by Wittig synthesis applied to different macroporous polystyrenes. Two pathways for chloromethylation led to surprising differences. The vinyl species were hydrostannylated and the products reduced to tin hydrides to furnish versatile reagents for organic synthesis. For each step, several methods were tested, and careful optimization was carried out. Some investigations on the properties of the new reactive polymers such as stability and leaching of tin are described.