염산계를 이용한 왕수 대체 고농도 금 침출 공정 연구
Study on High Concentration Gold Leaching Process Using Hydrochloric Acid System as an Alternative to Aqua Regia
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초록
폐전자제품에서 금을 회수하는 과정에서 왕수와 같은 유해 물질의 사용은 독성으로 인해 안전 및 환경 문제를 유발한다. 따라서, 유해물질 사용을 줄이고 작업 환경을 개선하며, 효율적이고 안정적인 금 회수 공정의 현장 적용을 위해서는 높은 금 농도를 확보할 수 있는 금침출 공정 개발이 필요하다. 본 연구에서는 왕수를 대체하는 금 침출 공정으로 염산과 산화제를 사용하는 금 침출 공정을 개발하였다. 염산 농도, 산화제 첨가량, 반응 온도를 주요 공정인자로 하여 금 침출 효율에 미치는 영향을 Taguchi 실험 설계를 통해 비교·분석하였고 실험 결과, 산화제 농도가 금 침출에 가장 큰 영향을 미쳤으며, 그 뒤로 염산 농도와 온도가 영향을 미치는 것으로 나타났다. 염산 농도, 산화제(과산화수소 및 차아염소산나트륨) 첨가량, 염화나트륨 첨가량에 따른 최적 조건을 도출하였다. 염산과 과산화수소의 경우, 7 M 염산, 1.163 M 과산화수소, 0.5 M 염화나트륨, 50℃ 조건에서 2시간 반응 시 금 침출률은 93.92 %이고, 18.135 g/L의 고농도 금 침출액을 나타내었다. 염산과 차아염소산나트륨의 경우에는 5 M 염산, 0.486 M 차아염소산나트륨, 50℃ 조건에서 2시간 반응 시 93.21 %의 금 침출률과 17.998 g/L의 고농도 금 침출액을 나타내었다.
Abstract
The use of hazardous chemicals, such as aqua regia, in the recovery of gold from waste electronic equipment presents safety and environmental risks owing to their toxicity. Therefore, to reduce the use of harmful chemicals, improve workplace safety, and enable efficient industrial gold recovery, developing a gold leaching-process capable of achieving high gold concentrations is essential. In this study, a gold leaching process was developed utilizing hydrochloric acid and an oxidizing agent as an alternative to aqua regia. The effects of hydrochloric acid concentration, oxidant dosage, and reaction temperature on gold leaching efficiency were investigated and analyzed using a Taguchi experimental design. The results indicated that oxidant concentration has the most significant impact on gold leaching, followed by hydrochloric acid concentration and temperature. The optimal conditions were determined on the basis of the hydrochloric acid concentration, amount of oxidizing agents (hydrogen peroxide and sodium hypochlorite), and amount of sodium chloride added. By using a hydrochloric acid-hydrogen peroxide system with 7 M hydrochloric acid, 1.163 M hydrogen peroxide, and 0.5 M sodium chloride, at 50°C for 2 h, the gold leaching efficiency of 93.92% was achieved, resulting in a high-concentration gold leaching solution of 18.135 g/L. Similarly, a gold leaching efficiency of 93.21 % was achieved, upon using a hydrochloric acid-sodium hypochlorite system with 5 M hydrochloric aicd and 0.486 M sodium hypochlorite at 50 ℃ for 2 h, resulting in a high-concentration gold leaching solution of 17.998 g/L.
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