• Resources Recycling
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• v.20 no.2
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• pp.45-53
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• 2011

We devised a procedure for the recovery of silicon and tempered glass from waste photovoltaic (PV) modules using optimized conditions. The tempered glass was recovered without any damage using organic solvents. The surface material is removed by applying an acid solution on the surface of the PV cell. Through our proposed method, we offer a much more efficient approach for recycling solar cells with a surfactant than the conventional method. This process, we obtained pure silicon with a yield of 90% by chemical treatment with the surfactant at room temperature for 18 min. The silicon yield was characterized using an inductively coupled plasma-atomic emission spectrometer.

• Proceedings of the Korean Institute of Resources Recycling Conference
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• 2004.05a
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• pp.186-190
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• 2004

실리콘 잉곳의 절단공정에서 발생하는 폐슬러지는 실리콘과 실리콘카바이드 등의 유가자원이 함유되어 있으며, 이를 효과적으로 분리, 회수하는 방법에 대해 검토하였다. 폐슬러지에 함유된 오일은 유기 용매에 의해 용해되어 효과적으로 분리되었고, 불순물인 철분은 자력선별에 의해 제거할 수가 있었다. 또한 실리콘과 실리콘카바이드의 혼합 분말은 중액선별을 통하여 고순도의 실리콘과 실리콘카바이드로 분리할 수가 있었다.

• Proceedings of the IEEK Conference
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• 2001.10a
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• pp.705-710
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• 2001

So for the quartz-glassy crucible wastes which was used for pulling up silicon-single-crystal ingot have simply reused for refractory raw-materials, or exhausted. This study is concerned on the advanced recycling-technology that is obtained by the proper micro-particle preparation process in order to fabricate fine amorphous silica filler for EMC (Epoxy Molding Compound). Therefore, this paper will deal with the physical, chemical and thermal pre-treatment process for efficient impurity removal and with the proper micro-particle process for producing the amorphous silicafiller. In view of the results, if the chemical, physical and thermal pre-treatment process for efficient elimination of impurity was passed, the purity of wasted fused glassy crucible is almost equal to the its of first anhydrous quartz glass. Thus, it was understood that this wasted fused glassy crucible was sufficient value of recycling, though it was damaged. When the ingot was fabricated, Phase transformation of crystallization by heat treatment (heat hysteresis phenomenon) was not changed. So, it was understood that as fused silica in the amorphous state, as It is, recycling possibility was very high

• Journal of the Microelectronics and Packaging Society
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• v.10 no.3
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• pp.67-71
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• 2003

Sawing silicon ingot with abrasive slurry generates sludge that includes abrasive powders, cutting oil, and silicon powders. The abrasive powders and cutting oil are being separated and reused. Mixing the remained stodged silicon powders with carbon powders and subsequent heat-treatment are conducted to produce silicon carbide. The size of SiC whiskers and powders was smaller than the conventionally grown silicon carbide whiskers that were synthesized by adding micron-size metal impurities. Impurity related mechanism is attributed to the formation of the silicon carbide whiskers, as metal impurities are contained in the stodged silicon powders.

• Resources Recycling
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• v.20 no.1
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• pp.61-68
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• 2011

Impurity removal from metallurgical grade silicon by acid washing at $50^{\circ}C$ was investigated by employing sulfuric, nitric acid and the mixture of hydrochloric and hydrofluoric acid. Acid washing treatment had no effect on the removal of boron and the concentration of this clement after treatment was rather increased. In our experimental range, the removal percentage of phosphorus was 60%. In the acid washing with sulfuric and nitric acid, the removal percentage of major impurities was below 50%, which indicates that refining effect was not great with these acids. Acid washing with the mixture of hydrochloric and hydrofluoric acid led to removal percentage of higher than 90%. Data on the purity of silicon after acid washing at various conditions are reported.

• Resources Recycling
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• v.21 no.3
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• pp.21-27
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• 2012

In order to make high-purity ferro-manganese from $Mn_3O_4$ dust, the application of aluminothermy process to the reduction of $Mn_3O_4$ dust was investigated in previous work. The result showed the fact that can be obtained high purity ferro-manganese which have over about 93% of manganese content and lower impurities such as C, P, S than those of KS D3712 specification. The addition of silicon powder instead of aluminum powder was investigated as reductant in the thermite reaction process of $Mn_3O_4$ dust in this work because its production cost is lower than that of aluminum powder. In case of addition of silicon powder only as reductant, the experimental result showed the unstable ignition and no thermite reaction of mixture, but in case of simultaneous addition of silicon and aluminum powders as reductant, showed the fact that can be obtained high purity ferro-manganese which have much low content of impurities such as C, P, S component.

• Resources Recycling
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• v.22 no.2
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• pp.37-43
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• 2013

Unlike the conventional slurry type wire sawing, the diamond wire sawing method adopts diamond plated wire as sawing media instead of slurry consisted of both silicon carbide and oil. Wafering with diamond plated wire leaves solid element of the sludge mostly made up of silicon, and it is not difficult to recover 95% or more of silicon by a simple separation process of oil from the sludge. In this study, silicon was recovered from the sludge by drying process and organic and metal impurities were removed by sintering process. As result 3N grade silica was obtained successfully by thermal processing utilized the fact that the recovered silicon readily combines with oxygen due to fine particle size.

• Resources Recycling
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• v.22 no.2
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• pp.22-28
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• 2013

In the present study, the possibility of recovering and recycling the silicon carbide(SiC) from a silicon sludge by removing Fe and Si impurities was investigated. Si and SiC were separated from the silicon sludge using centrifugation. The separated SiC concentrate consisted of Fe, Si and SiC, in which Fe and Si were removed to recover the pure SiC. Leaching with acid/alkali solution was compared with the vapor-phase chlorination. The Fe concentration removed in the SiC was 49 ppm, and it was separated by leaching with 1 M HCl solution at $80^{\circ}C$ for 1 h. The Si concentration removed in the SiC was 860 ppm, and it was separated by leaching with 1M NaOH solution at $50^{\circ}C$ for 1 h. The SiC concentrate was chlorinated in a tubular reactor, 2.4 cm in diameter and 32 cm in length. The boat filled with SiC concentrate was located at the midpoint of the alumina tube, then, the chlorine and nitrogen gas mixture was introduced. The Fe and Si concentration removed in the SiC were 48 ppm and 405 ppm, respectively, at $500^{\circ}C$ reactor temperature, 4 h reaction time, 300 cc/min gas flow rate, and 10% $Cl_2$ gas mole fraction.

• Resources Recycling
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• v.31 no.6
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• pp.60-65
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• 2022

This study presents the carburization process for recycling sludge, which was formed during silicon wafer machining. The sludge used in the carburization process is a mixture of silicon and silicon carbide (SiC) with iron as an impurity, which originates from the machine. Additionally, the sludge contains cutting oil, a fluid with high viscosity. Therefore, the sludge was dried before carburization to remove organic matter. The dried sludge was washed by acid cleaning to remove the iron impurity and subsequently carburized by heat treatment under vacuum to form the SiC powder. The ratio of silicon to SiC in the sludge was varied depending on the sources and thus carbon content was adjusted by the ratio. With increasing SiC content, the carbon content required for SiC formation increased. It was demonstrated that substoichiometric SiC_x (x<1) was easily formed when the carbon content was insufficient. Therefore, excess carbon is required to obtain a pure SiC phase. Moreover, size reduction by high-energy milling had a beneficial effect on the suppression of SiC_x, forming the pure SiC phase.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.26 no.5
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• pp.171-174
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• 2016

The diamond wire sawing method to produce silicon wafers for the photovoltaic application is still a new and highly investigated wafering technology. This technology, featured as the higher productivity, lower wear of the wire, and easier recycling of the coolant, is expected to become the mainstream technique for slicing the silicon crystals. However, the saw marks on the wafer surface have to be investigated and improved. This paper discusses the removal of saw marks on diamond wire-sawn single crystalline silicon wafer. With a pretreatment step using tetramethyl ammonium hydroxide ($(CH_3)_4NOH$, TMAH) and conventional texturing process with KOH solution (1 % KOH, 8 % IPA, and DI water), the saw marks on the surface of the diamond wire-sawn silicon wafers can be effectively removed and they are invisible to naked eyes completely.