Gold Recovery using Porphyrin-based Polymer from Electronic Waste: Adsorbent Regeneration and Reuse

( Jieun Sona ),( Cafer T. Yavuz ),( Yeongran Hong ),( Thien Nguyen ),( Jong-in Han ) 한국폐기물자원순환학회(구 한국폐기물학회) 2019 ISSE 초록집 Vol.2019 No.-

Due to the rapid development of innovations, the amount of discarded electrical or electronic equipment, called electronic wastes, have been gradually increased over the world and as a consequence, the treatment of the wastes brought a great attention to many researchers. Despite its small amount, precious metals in electronic wastes have large potential values as a future secondary source of metals. However, separation and refining of these metals are complicated and none of them are chosen to be commercialized. As one of the promising adsorbents, porphyrin-based porous polymer, named COP-180, has been developed for the selective adsorption and separation of gold. Although the characteristics and adsorption abilities of COP-180 has been deeply investigated, the strategies on the desorption and recovery of adsorbed gold and the regeneration of the polymer are still unknown. Herein, a hydrometallurgical method for efficient gold desorption and recovery from COP-180 was suggested. Chloride, thiosulfate and thiourea, which are typical non-cyanide gold leaching solutions, were evaluated for gold desorption from the polymer. Leaching solution of thiourea in acidic condition provided the best desorption performance. The results of FTIR analysis showed that the structure of COP-180 was maintained during desorption with thiourea, while changes of structures were detected with acid chloride solution as it supported the suitability of thiourea in either gold desorption or adsorbent regeneration. The ratio of adsorbed gold over the polymer was varied to analyze its effect on desorption efficiency. The less amount of gold was adsorbed on the polymer, the higher gold desorption efficiency was obtained. More than 98% of the adsorbed gold was desorbed from COP-180 by the treatment of 0.1M of thiourea for 2 hours at 50°C. The regeneration and reusability of the adsorbent was evaluated in three consecutive cycles. All these present works suggested that the desorption method via acid thiourea can offer a workable way of efficient gold recovery and regeneration of the adsorbent.

Optimization of gold recovery from copper anode slime by acidic ionic liquid

Aydın Rüşen,Mehmet Ali Topçu 한국화학공학회 2017 Korean Journal of Chemical Engineering Vol.34 No.11

Hydrometallurgical gold recovery from primary or secondary sources is mainly based on a cyanide process, which is very dangerous for the environment due to the high toxicity levels. In view of the environmental effect, the present study proposes a new green solvent called 1-ethyl-3-methyl-imidazolium hydrogen sulfate (EmimHSO4) ionic liquid (IL) to recover gold from copper anode slime (CAS). The optimum leaching conditions for maximizing gold recovery were determined by orthogonal array (OA) of Taguchi’s experimental design method. OA L16 (44) including four parameters with four levels each, was used to examine the effects of IL concentration (20%, 40%, 60%, 80% v/v), temperature (25, 50, 75, 95 oC), time (½, 1, 2, 4 h) and solid/liquid ratio (1/10, 1/15, 1/20, 1/25 g/mL) on leaching efficiency of the gold recovery. Statistical analysis of variance (ANOVA) was used to determine the relevance between experimental conditions and gold recovery. The selective leaching tests results showed that gold recovery up to 89.07% was attained on laboratory scale under the optimum leach conditions: 80% IL concentration, 75 oC, 4 h and 1/25 g/mL solid/liquid ratio. According to these results, EmimHSO4 IL provides a very good ambiance for the oxidative leaching of gold and can be offered as an alternative leaching agent instead of harmful cyanide-based solvents.

Simultaneous Recovery of Gold and Iodine from the Waste Rinse Water of the Semiconductor Industry Using Activated Carbon

Nguyen, Nghiem V.,Jeong, Jinki,Shin, Doyun,Kim, Byung-Su,Lee, Jae-chun,Pandey, B. D. The Japan Institute of Metals 2012 Materials Transactions Vol.53 No.4

<P>This research work focused on the simultaneous recovery of gold (40.5 mg/dm<SUP>3</SUP>) and iodine (748 mg/dm<SUP>3</SUP>) from the waste rinse water of the semiconductor industry using activated carbon. A batch study was conducted to optimize process parameters, such as contact time and carbon dose, for the recovery of gold and iodine from the waste water. The loading capacity of the activated carbon for adsorption of gold and iodine was found to be 33.5 mg Au/g carbon and 835 mg I<SUB>2</SUB>/g carbon, respectively. Gold was found to exist on the activated charcoal surface in two forms: ionic gold and elemental gold. Aqua regia was used to convert metallic gold to its ionic form, and the iodine and the small amount of ionic gold were removed from the activated carbon by elution with aqua regia. Gold was recovered from the eluate by reduction with hydrazine. Iodine from the diluted aqua regia was then precipitated by adding sodium hydrosulfite (Na<SUB>2</SUB>S<SUB>2</SUB>O<SUB>4</SUB>). A complete process flow sheet was developed to recover both gold and iodine from the waste water of the semiconductor industry, which conserves the resources while meeting environmental pollution requirements.</P>

생체흡착, 탈착 및 회화를 이용한 시안 용액으로부터 금의 회수

배민아(Min A Bae),곽인섭(In-Seob Kwak),원성욱(Sung Wook Won),윤영상(Yeoung-Sang Yun) 한국청정기술학회 2010 청정기술 Vol.16 No.2

본 연구에서는 Au(I) 이온을 함유한 시안 용액으로부터 다른 형태의 금을 회수하기 위하여 생체흡착 후 탈착하는 방법과 생체흡착 후 회화하는 방법을 제안하였다. 생체흡착제로는 아미노산 발효 공정에서 발생하는 균체 폐기물(Corynebacterium glutamicum)을 사용하였다. 바이오매스의 흡착 특성을 알아 보기 위하여 pH edge 실험을 수행하였으며, 그 결과 흡착성능은 pH 2-3 부근에서 우수한 결과를 보였다. 또한, 등온흡착 실험 결과를 Langmuir 모델에 적용한 결과 Au(I)의 최대 흡착량은 pH 2.5에서 35.15 mg/g이었다. 흡착 속도론 실험을 통해 흡착 평형은 60분 이내의 짧은 시간 내에 이루어지는 것을 확인하였다. Au(I)을 회수하기 위하여 바이오매스에 흡착된 Au(I)을 탈이온수를 이용하여 탈착을 시켰으며, 탈착효율은 91%로 평가되었다. 이 결과는 바이오매스를 이용하여 흡착과 탈착을 통해 1가 금을 효과적으로 회수할 수 있음을 보여준다. 영가 형태로 회수하기 위하여, 금을 흡착하고 있는 생체흡착제를 회화하여 환원된 형태의 금을 성공적으로 회수하였으며, 회분 중 금의 순도는 85% 이상이었다. 따라서 본 연구에서 제시한 생체흡착 후 탈착(1가 형태) 공정과 생체흡착 후 회화(영가 형태) 공정은 회수하고자 하는 금의 산화수에 따라 선택하여 사용될 수 있을 것으로 기대된다. In this study, we propose two methods able to recover different type of gold from gold-cyanide solutions: biosorption and desorption process for mono-valent gold recovery and biosorption and incineration process for zero-valent gold recovery. The waste bacterial biomass of Corynebacterium glutamicum generated from amino acid fermentation industry was used as a biosorbent. The pH edge experiments indicated that the optimal pH range was pH 2 - 3. From isothermal experiment and its fitting with Langmuir equation, the maximum uptake capacity of Au(I) at pH 2.5 were determined to be 35.15 mg/g. Kinetic tests evidenced that the process is very fast so that biosorption equilibrium was completed within the 60 min. To recover Au(I), the gold ions were able to be successfully eluted from the Au-loaded biosorbent by changing the pH to pH 7 and the desorption efficiency was 91%. This indicates that the combined process of biosorption and desorption would be effective for the recovery of Au(I). In order to recover zero-valent gold, the Au-loaded biosorbents were incinerated. The content of zero-valent gold in the incineration ash was as high as 85%. Therefore, we claim on the basis of the results that two suggested combined processes could be useful to recover gold from cyanide solutions and chosen according to the type of gold to be recovered.

An alternative to cyanide leaching of waste activated carbon ash for gold and silver recovery via synergistic dual-lixiviant treatment

Charlie R. Adams,Christopher P. Porter,Thomas J. Robshaw,James P. Bezzina,Victoria R. Shields,Alan Hides,Richard Bruce,Mark D. Ogden 한국공업화학회 2020 Journal of Industrial and Engineering Chemistry Vol.92 No.-

This study reports the development of a hydrometallurgical treatment for activated carbon ash (ACA); awaste product of the carbon-in-pulp (CIP) process used in the gold mining industry, rich in adsorbedprecious metals. After an initial screening of known leaching chemistries, the research focusses on duallixiviant(thiourea and thiocyanate) and thiourea systems, both of which have lower environmentalimpact than traditional cyanide leaches. Comparing ferric sulfate and hydrogen peroxide as oxidantsshowed that a thiourea leach is more suited to ferric sulfate whereas the dual-lixiviant leach achievedgreater extraction with hydrogen peroxide. This was believed to be due to a more favourable effective[thiourea]:[thiocyanate] molar ratio in solution. The latter demonstrated faster kinetics and improvedefficiency for dissolution of gold and silver. However, both leaches had issues with silver extraction due toformation of passivating layers on the surface of the silver nanoparticles. Kinetic modelling showed bothsystems tended towards a mixed-controlled process. Gold extraction of 89%, with leaching reachingequilibrium within 100 min, using the dual-lixiviant process demonstrated that there is an alternative tocyanide leaches employed in gold recovery.

Tunichrome-Inspired Gold-Enrichment Dispersion Matrix and Its Application in Water Treatment: A Proof-of-Concept Investigation

Dwivedi, Amarendra Dhar,Permana, Rega,Singh, Jitendra Pal,Yoon, Hakwon,Chae, Keun Hwa,Chang, Yoon-Seok,Hwang, Dong Soo American Chemical Society 2017 ACS APPLIED MATERIALS & INTERFACES Vol.9 No.23

<P>Tunicate, a filter-feeder in seawater, is able to accumulate high amount of metals using intracellular polymer matrices. The woven pyrogallol structures of tunichrome, a small peptide contained in tunicate's blood;Cells, is believed to, be responsible for selective. metal sequestration in tunicates from seawater. However, the intriguing tunichrome matrix is difficult both to harvest from the tunicate and to synthesize massively due to the-extreme oxidation sensitivity of the pyrogallol, moiety which limits the study scope. Here, we succeeded to mimic tunichrome by conjugating two cheap and naturally occurring components: pyrogallol-5-carboxylic acid (gallic acid) and chitin. nanofiber A tunicate-mimetic infiltration matrix of surface-tailored chitin nanofibers with pyrogallol moieties (CGa) demonstrated the versatility of this strategy in generation of ingenious filtration material, especially for unprecedented fine and-Clean gold recovery inside of the tunicate-mimetic infiltration matrix (>99%, 533 mg gold per gram weight), which exceeds that of the,presently most popular materials. Complexation between pyrogallol on the nanofiber and gold-was similar to that of a tunichrome's metal sequestration. Extended X-ray absorption fine Structure, (EXAFS); spectroscopy and data-fitting, elucidated the decreased coordination numbers for Au-Au nearest neighbors, demonstrating that gold coordinated to pyrogallol units, followed by an intramolecular association of Au-0. A catalytic reduction of 4-nitrophenol mediated by the-tunicate-mimetic matrix with harvested gold revealed excellent recyclability up to 30 cycles (similar to 95% reduction), which together with methylene-blue reduction and antimicrobial performances indicates the versatile characteristics,of sustainable processes by the tunichrome mimetics. This strategy opens the door for fast-developing new biomimetic alternatives for precious metal recovery, which is not restricted to gold and can offer a tool for multifaceted soft/hard nanomaterials..</P>

Dowex 21K XLT 수지를 이용한 산업폐수 내의 금-시안 착화합물의 선택적인 연속흡착 및 회수

전충(Choong Jeon) 한국지반환경공학회 2015 한국지반환경공학회논문집 Vol.16 No.3

Dowex 21K XLT 수지를 이용하여 산업폐수 내에 존재하는 금과 납-시안 착화합물에 대한 연속흡착 및 회수 특성을 조사하였다. 충전층에 충진된 Dowex 21K XLT 수지는 0.5mL/min의 유입유속에서 금-시안 착화합물을 520 bed volume까지 95% 이상 연속적으로 제거할 수 있지만, 납-시안 착화합물은 전혀 제거할 수 없었다. Dowex 21K XLT 수지에 흡착된 금-시안 착화합물은 HCl과 Acetone을 7:3의 비율로 섞은 혼합액을 탈착제로 이용하였을 때, 8 bed volume 내에서 96% 탈착되어졌다. 또한 두 번 재사용된 Dowex 21K XLT 수지의 금-시안 착화합물에 대한 bed volume이 490을 유지하여 향후 금 이온을 포함하고 있는 산업폐수 처리공정에 충분히 적용될 수 있을 것으로 판단된다. Continuous adsorption and recovery characteristics for gold and lead-cyanide complexes in industrial wastewater were investigated by the Dowex 21K XLT resin. The Dowex 21K XLT resin could continuously remove over 95% for gold-cyanide complex until 520 bed volumes at the 0.5 mL/min of influent flow rate, however, could not remove lead-cyanide complex at all. The 96% of gold-cyanide complex adsorbed onto Dowex 21K XLT resin could be recovered by mixed solvent with HCl and acetone (7:3 ratio) within 8 bed volumes. Also, the bed volume for gold-cyanide complex using secondly reused Dowex 21K XLT resin was maintained as the 490, therefore, continuous process using Dowex 21K XLT resin can be sufficiently applied to the industrial wastewater containing gold ions.

Selective removal of gold-cyanide complex from industrial wastewater using Dowex 21K XLT resin

차주현,전충 한국공업화학회 2015 한국공업화학회 연구논문 초록집 Vol.2015 No.1

Continuous adsorption and recovery characteristics for gold and leadcyanide complexes in industrial wastewater were investigated by the Dowex 21K XLT resin. The Dowex 21K XLT resin could continuously remove over 95% for gold-cyanide complex until 520 bed volumes at the 0.5 mL/min of influent flow rate, however, could not remove leadcyanide complex at all. The 96% of gold-cyanide complex adsorbed onto Dowex 21K XLT resin could be recovered by mixed solvent with HCl and acetone (7:3 ratio) within 8 bed volumes. Also, the bed volume for gold-cyanide complex using secondly reused Dowex 21K XLT resin was maintained as the 490, therefore, continuous process using Dowex 21K XLT resin can be sufficiently applied to the industrial wastewater containing gold ions.

Combined processes of biosorption, desorption and incineration for the recovery of gold from gold-cyanide solution with inactive waste biomass of Corynebacteriumglutamicum

Min A BAE,In-Seob KWAK,Yeoung-Sang YUN 한국생물공학회 2009 한국생물공학회 학술대회 Vol.2009 No.4

Electrowinning of gold from a dilute solution using hydrocyclone-type cell

Bae Mooki,Kim Hongin,Kim Sookyung,Lee Hyunju 한국자원공학회 2022 Geosystem engineering Vol.25 No.4

The redox reaction mechanism of gold−cyanide [Au(CN)2 −] during hydrocyclone electrowinning was investigated in this work by conducting Hull cell test, potentiodynamic polarization, and computational fluid dynamics (CFD) simulations. A leaching solution of waste printed circuit boards (WPCBs) was prepared as an electrolyte, and the effects of flow rate and applied voltage on the recovery of gold and destruction of cyanide through hydrocyclone electrowinning were investigated. A numerical simulation of the flow field in the cell was performed, and the results were visualized by conducting a finite element analysis in FLUENT. The CFD simulations and Hull cell test showed that the cylindrical cathode region had a flow velocity of ~11.05 m·s−1, which was higher than that at the center of the cylindrical part (<6.45 m·s−1). The optimum conditions for electrowinning were found to be as: an electrode distance of 4.9 mm and a current density of 73.78 mA·cm−2. The anodic polarization results showed that an Ir-based mixed metal oxide (MMO) anode could more efficiently oxidize the free cyanide because of its high current density than other types of anodes (Ir-based MMO: 299.3 mA·cm−2 > SS304: 3.5 mA·cm−2 > Pt-coated Ti: 1.3 mA·cm−2). Through the demonstrated hydrocyclone electrowinning test, the gold concentration could be decreased from 100 to 0.24 mg·L−1 within 12 h while destroying almost total amount of free cyanide in a day.