High-purity Selenium Research Articles

An innovative green method for efficient extraction of selenium by melt filtration-vacuum distillation

High-purity selenium is important for technological innovation in fields such as aerospace, military, new energy, and semiconductors, and has become a hot topic in developed countries. Unfortunately, traditional preparation of high-purity selenium faces challenges such as high cost, environmental pollution, and low efficiency. In this study, we introduce an innovative green method that efficiently extracts selenium from crude selenium by combining melt filtration and vacuum distillation. Our approach effectively addresses these challenges. We calculated the potential reactions of the impurities in the selenium melt and analyzed the saturated vapor pressures of various substances. The experimental results showed that volatile impurities such as PbSe and PbTe were largely removed in the form of filter residues during the melt filtration of crude selenium residue at 653 K. The filtered selenium melt was distilled for 120 min at 533 K to obtain refined Se with a total purity of 99.9 %. Through the melt filtration-vacuum distillation process, the removal rates of impurity elements Cu, Pb, As, and Te were 99.35 %, 99.97 %, 99.83 %, and 81.11 %, respectively. Impurity elements were enriched and recovered from the filter and distillation residues. The refined Se was efficiently recovered from crude selenium, and the economic benefits were superior to other processes. This process meets the demands of a clean and efficient selenium metallurgy industry.

Removing of Fe, Pb and Hg from Crude Selenium by Fractional Crystallization

This paper focuses on a fractional crystallization methodology using a rotating and internally gas-cooled crystallizer to purity crude selenium. Experiments using a rotating and gas-cooled crystallizer (cooled finger) were performed. The distribution coefficients of the main impurities (Pb, Fe and Hg) in selenium were presented as a polynomial function of concentration. The experimental parameters such as crystallization temperature and rotation rate were determined and discussed. The appropriate crystallization temperature is 222 °C and the rotation rates are 120 and 300 rpm, respectively. The purity of crude selenium increased from 99.9% to over 99.997%. Compared with the traditional method such as zone melting, this method only takes less than one day to complete several purifications, and the purification effect is better than the former. The removal rates of Hg, Pb and Fe in Se are 28.70%, 97.63% and 96.28%, respectively. The direct yield of Se purified is 92.5%. This study provides an efficient process for high-purity selenium, which has important industrial applications.

Phase Control of Typical Impurities in Hazardous Selenium Waste and Preparation of High-Purity Selenium During Pre-oxidation and Vacuum Distillation Process

Phase Control of Typical Impurities in Hazardous Selenium Waste and Preparation of High-Purity Selenium During Pre-oxidation and Vacuum Distillation Process

Model-based analyses of chromate, selenate and sulfate reduction in a methane-based membrane biofilm reactor

Selenate (SeO42−) and sulfate (SO42−) are frequently present together with chromate (CrO42−) in certain industrial wastewaters. SeO42− and CrO42− are required to be reduced while SO42− reduction should be minimized to avoid the production of toxic sulfide. In this study, a modified biofilm model was employed to investigate the interactions between CrO42−, SeO42− and SO42− bioreduction in a methane (CH4)-based membrane biofilm reactor (MBfR). The model was calibrated using steady-state experimental data of two reported CH4-based MBfRs reducing these oxyanions. The modeling results suggested that the majority of methanotrophs (>80%) were located in the outer layer of the biofilm, while the oxyanions-reducing bacteria preferred to grow close to the membrane. The introduction of SeO42− or SO42− enriched selenate/sulfate-reducing bacteria (SeRB/SRB) but decreased the abundance of chromate-reducing bacteria (CRB). A biofilm thickness of >300 μm, an HRT of higher than 4 h and an influent dissolved oxygen concentration of 0.3 mg /L were favorable for simultaneous high-level CrO42− and SeO42− removal. A two-stage MBfR system with optimized operational conditions showed promise in retaining high-purity (>98%) selenium nanoparticles when treating both CrO42− and SeO42− impacted wastewaters. Moreover, the model indicated that efficient CrO42− removal (>90%) along with minor SO42− reduction (<10%) could be realized via maintaining appropriate biofilm thickness (200-250 μm) and influent dissolved oxygen (0.7–0.8 mg /L) in a single MBfR. These findings offer insights for the design and operation of CH4-based technology for remediating CrO42− contaminated industrial wastewaters.

Innovative green approach for the selective extraction of high-purity selenium from hazardous selenium sludge

Hazardous selenium sludge is a critical intermediate byproduct of the comprehensive recovery of selenium from copper anode slime, and the sustainable extraction of Se is an important basis for the development of high-tech Se-containing materials. Unfortunately, current processes are constrained by complex procedures, serious pollution, ineffectiveness and difficulty in separating Se-Te. This study has developed an innovative green approach utilizing the phase transformations of impurities combined with vacuum distillation to efficiently extract high-purity selenium from selenium sludge and to overcome these issues. The main impurities of Te, Cu, and Pb exist as elemental Te, PbTe, TeO, Cu2Se, and PbSe, and a green oxidizing reagent (H2O2) is employed to convert these impurities into low volatile TeO, CuSeO3, and PbSeO3. Then, high-purity selenium (Se 99.998%) is extracted by vacuum distillation. The appropriate dose of H2O2 is 15 ml per 100 g of sludge at 300 rpm, 0.5 h, and room temperature. Furthermore, the optimal vacuum distillation conditions are 733 K, 1 h, and 1–10 Pa. After completing the whole process, the total yield of high-purity selenium reaches 87.86%. This study provides an efficient and environmentally friendly process to dispose of hazardous selenium sludge and extract high-purity selenium for further use, which has important industrial applications.

Innovative technologies providing enhancement of non-ferrous, precious, rare and rare earth metals extraction

The article provides the technologies of enrichment and metallurgy processing of mineral and man-made raw materials. New technical solutions are proposed to increase the end-to-end copper extraction, industrial products processing of copper production to obtain high purity selenium; extraction of gold from resistant mineral raw materials with the use of new reagents and equipment, processing of ferrous bauxite and alumina production waste, extraction of rare and rare earth metals from industrial products and wastes of chrome, phosphorus and uranium production, obtaining rhenium and Nickel-cobalt concentrate from the wastes of heat-resistant Nickel alloys. Innovative Bayer-hydrogenative technology of ferruginous bauxite processing was developed and tested using pilot facility. The technologies and equipment to produce a composite hydrogen permeable membrane based on niobium and obtaining castings of implants by casting method of titanium alloys with application of additive technologies were developed.

Investigation of an Electrochemical Method for Separation of Copper, Indium, and Gallium from Pretreated CIGS Solar Cell Waste Materials.

Recycling of the semiconductor material copper indium gallium diselenide (CIGS) is important to ensure a future supply of indium and gallium, which are relatively rare and therefore expensive elements. As a continuation of our previous work, where we recycled high purity selenium from CIGS waste materials, we now show that copper and indium can be recycled by electrodeposition from hydrochloric acid solutions of dissolved selenium-depleted material. Suitable potentials for the reduction of copper and indium were determined to be −0.5 V and −0.9 V (versus the Ag/AgCl reference electrode), respectively, using cyclic voltammetry. Electrodeposition of first copper and then indium from a solution containing the dissolved residue from the selenium separation and ammonium chloride in 1 M HCl gave a copper yield of 100.1 ± 0.5% and an indium yield of 98.1 ± 2.5%. The separated copper and indium fractions contained no significant contamination of the other elements. Gallium remained in solution together with a small amount of indium after the separation of copper and indium and has to be recovered by an alternative method since electrowinning from the chloride-rich acid solution was not effective.

Evaluation of High-Temperature Chlorination as a Process for Separation of Copper, Indium and Gallium from CIGS Solar Cell Waste Materials

CIGS (copper indium gallium diselenide) is a semiconductor used in high efficiency thin film solar cells. Several of these elements are considered to be fairly rare and thus expensive. In order to ensure future supply of the metals, an efficient recycling process for CIGS is needed. We have previously published a process for the separation of high purity selenium from CIGS solar cell waste materials. In the present paper we evaluate the possibility of using high-temperature chlorination to separate copper, indium, and gallium from the residue obtained in the selenium separation process. The chlorination agents used were chlorine gas, hydrogen chloride gas, and ammonium chloride. The goal was to use different temperatures to separate the metal chlorides formed. Ammonium chloride was shown to be the most promising chlorination agent for future process optimization.

Recycling of high purity selenium from CIGS solar cell waste materials

Copper indium gallium diselenide (CIGS) is a promising material in thin film solar cell production. To make CIGS solar cells more competitive, both economically and environmentally, in comparison to other energy sources, methods for recycling are needed. In addition to the generally high price of the material, significant amounts of the metals are lost in the manufacturing process. The feasibility of recycling selenium from CIGS through oxidation at elevated temperatures was therefore examined. During oxidation gaseous selenium dioxide was formed and could be separated from the other elements, which remained in solid state. Upon cooling, the selenium dioxide sublimes and can be collected as crystals. After oxidation for 1h at 800°C all of the selenium was separated from the CIGS material. Two different reduction methods for reduction of the selenium dioxide to selenium were tested. In the first reduction method an organic molecule was used as the reducing agent in a Riley reaction. In the second reduction method sulphur dioxide gas was used. Both methods resulted in high purity selenium. This proves that the studied selenium separation method could be the first step in a recycling process aimed at the complete separation and recovery of high purity elements from CIGS.

Thermal-Neutron Capture Cross Sections and Resonance Integrals of the 80Se(n,γ)81m,81gSe Reactions

The thermal-neutron capture cross sections (σ0,m and σ0,g) and resonance integrals (I 0,m and I 0,g) leading to the isomeric and ground states of 81Se were measured by the activation method. Samples of high-purity (99.99%) selenium oxide were irradiated in a rotary specimen rack of the research reactor of Rikkyo University. Wires of Co/Al and Au/Al alloys, which have different sensitivities to neutrons in the thermal and epithermal energy regions, were irradiated to monitor the thermal neutron fluxes and the epithermal components at the same position of the rotary specimen rack. The cadmium-shielded samples were also irradiated to obtain the cadmium ratio and the resonance integrals (I 0,m and I 0,g). A high-purity Ge detector was used to measure the γ-rays emitted from the irradiated samples and wires, and reaction rates were calculated from γ-ray yields. On the basis of Westcott's convention, the cross sections were obtained as follows: σ0,m = 0.057 ± 0.003 b and I 0,m = 0.186 ± 0.014 b leading to 81mSe, and σ0,g = 0.536 ± 0.046 b and I 0,g = 0.867 ± 0.102 b leading to 81gSe.

Macro micro separation of selenium and tellurium: Application to NAA&lt;/p&gt; &lt;/p&gt;

A simple pre-irradiation separation approach has been worked out for the determination of traces of tellurium in high purity selenium followed by neutron activation analysis (NAA) for the end determination of the analyte/s. The difference in volatilities of these elements has been utilized for the separation of the analyte from the matrix. The complete volatility of selenium at ~600 °C was established using neutron activation analysis and selenium radiotracer. Standard addition was used to validate the results. The proposed method of separation of selenium prior to irradiation could make the determination of tellurium possible and also improved the detection limit by several folds.

Compositional dependence of optical properties of hot wall deposited CdSexTe1-x thin films

CdSexTe1–x (0 ≤ x ≤ 1) ternary thin films have been deposited on well-cleaned glass substrates by a hot wall deposition technique, using source materials prepared by direct reaction of high-purity elemental cadmium, selenium and tellurium. The composition of the deposited films has been studied using energy-dispersive analysis of X-rays. The effect of composition on the optical properties has been studied. The optical studies showed a quadratic variation of band gap with composition. The energy band gap was a minimum (1.39 eV) for the composition CdSe0.4Te0.6. The refractive index of the films has been determined using the transmittance spectra. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Production of selenium powder from anode slimes

Hazardous selenium sludge is a critical intermediate byproduct of the comprehensive recovery of selenium from copper anode slime, and the sustainable extraction of Se is an important basis for the development of high-tech Se-containing materials. Unfortunately, current processes are constrained by complex procedures, serious pollution, ineffectiveness and difficulty in separating Se-Te. This study has developed an innovative green approach utilizing the phase transformations of impurities combined with vacuum distillation to efficiently extract high-purity selenium from selenium sludge and to overcome these issues. The main impurities of Te, Cu, and Pb exist as elemental Te, PbTe, TeO, Cu2Se, and PbSe, and a green oxidizing reagent (H2O2) is employed to convert these impurities into low volatile TeO, CuSeO3, and PbSeO3. Then, high-purity selenium (Se 99.998%) is extracted by vacuum distillation. The appropriate dose of H2O2 is 15 ml per 100 g of sludge at 300 rpm, 0.5 h, and room temperature. Furthermore, the optimal vacuum distillation conditions are 733 K, 1 h, and 1–10 Pa. After completing the whole process, the total yield of high-purity selenium reaches 87.86%. This study provides an efficient and environmentally friendly process to dispose of hazardous selenium sludge and extract high-purity selenium for further use, which has important industrial applications.

High-Purity As2S1.5Se1.5 Glass Optical Fibers

Core–clad optical fibers were fabricated from high-purity As2S1.5Se1.5 glass, and their properties were studied. The arsenic sulfo-selenide was prepared by melting a mixture of high-purity arsenic monosulfide, arsenic, and selenium. Optical fibers with core/clad diameters of 300/400 and 200/400 μm were fabricated by the double-crucible method. The minimum loss was found to be 60 ± 20 dB/km at 4.8 μm and 200–300 dB/km between 4 and 6 μm. The numerical aperture of the fibers was 0.28. A 1.5-m-long section of the fiber transmitted 6-W CO laser radiation. The average bending strength of the 400-μm-diameter fibers was 0.8 GPa.

Optimization of spectral determination of impurities in high-purity selenium

We carried out a complex of investigations concerned with optimization of the conditions and reduction of the limits of atomic-emission determination of impurities in high-purity selenium. We investigate the possibility that the types of impurities in the references can affect the results of analysis.

Determination of impurities in high-purity selenium by inductively coupled plasma mass spectrometry after acetate-form anion-exchange separation

A rapid and sensitive method has been developed for the determination of lithium, manganese, zinc, arsenic, silver, cadmium, tellurium and lead in high-purity selenium at ng g −1 level. These elements are separated with a strongly basic anionexchange resin, Dowex 1-X8, in the acetate form and determined by inductively coupled plasma mass spectrometry. Since selenium, as selenious acid, is strongly adsorbed on the resin in the acetate form, the other elements can be eluted with dilute nitric acid (0.1–1.4 moll −1) before the elution of selenious acid. For spike additions between 50 and 1000 ng g −1 of these elements, good recoveries are obtained with errors between 1% and 6%. The limits of quantitation of impurities in high-purity selenium are 1 ng g −1 for lithium, 5 ng g −1 for manganese, 70 ng g −1 for zinc, 2 ng g −1 for arsenic, 8 ng g −1 for silver, 1 ng g −1 for cadmium, 5 ng g −1 for tellurium and 10 ngg −1 for lead.

Determination of Impurities in High-Purity Selenium by Inductively Coupled Plasma Mass Spectrometry after Matrix Separation with Thiourea

Determination of Impurities in High-Purity Selenium by Inductively Coupled Plasma Mass Spectrometry after Matrix Separation with Thiourea

Solidification of selenium melt under pressure up to 6.5 GPa

Abstract High purity selenium samples were melted under high pressure (≤6.4 GPa) and quenched at various rates ranging from 2 K s−1 to 500 K s−1 and the recovered material was examined by X-ray diffraction and electron microscopy. In the entire range of pressure and cooling rate, the melt was found to solidify into a polycrystalline aggregate of the trigonal phase of selenium. The samples obtained by slow cooling of the melt at 6.4 GPa contain, in addition to crystalline phase, regions which appear to be amorphous.

Microtrace determination in high-purity selenium

Microtrace determination in high-purity selenium

Phase relations and equilibrium copolymerization in the SeS system

The phase relations in the SeS system were investigated by the appearance of phase method, differential thermal analysis, and differential scanning calorimetry. High purity selenium melts at 216 ± 2°C. A peritectic exists at 85 at. % Se and 168 ± 2°C; the peritectic isotherm extends from 92 to 73.5 at. % Se. A temperature minimum of 102 ± 1°C exists at a composition of 35 ± 1 at. % Se. High purity sulfur melts at 114 ± 1°C and polymerizes at 160 ± 2°C. Addition of 10 at. % Se lowers the polymerization temperature to 118 ± 3°C. The SeS system shows complete liquid miscibility and in this respect it differs from the majority of selenide type systems that generally show one or more fields of liquid immiscibility. The complete liquid miscibility in the SeS system can best be explained by the equilibrium copolymerization theory. Investigation of the subsolidus relations in the SeS system shows a miscibility gap in the Se-rich part of the system. The eutectoid proposed by W. E. Ringer ( Z. Anorg. Chem. 32, 183 (1902)) in the S-rich part of the system was not detected.