알카리 침출법을 이용한 WC/Co 초경스크랩의 재자원화

Abstract

The present study focused on the recycling of WC/Co hardmetal scrap by alkaline leaching method. WC/Co sludge was oxidized and put the sludge oxide into NaOH solution to leach tungsten. Tungsten leached liquor was purified and decreased its pH to precipitate tungsten. The process variables were leaching temperature, concentration of NaOH solution, leaching time, purification substance and pH of purified tungsten liquor. The phase structure, components, particle size of the sludge, oxidized sludge, and precipitates were analysed using XRD, XRF and SEM. The concentration of remained impurities in liquor were analysed using ICP. Tungsten leaching rate was increased by increasing of temperature and concentration of NaOH solution and not affected by the increasing of time. Concentration of impurities remained in leached liquor were constant in spite of the increasing of input of Na2S and HCl. It was more effective to purify the liquor to use HCl. Precipitation rate of tungsten from purified liquor was increased to 94% by decreasing of pH until pH–0.4 and decreased after pH –0.4. The precipitate has 100~300nm of irregular shape and it was high purity of H2WO4·H2O regardless of decreasing of pH.