Chemical Phase Analysis of Arsenic Ores—A Study on Selective Separation Conditions of Orpiment and Realgar

As a rich symbiotic mineral resource, orpiment (As₂S₃) and realgar (AsS/As₂S₂/As₄S₄) are common sulfide minerals of arsenic. However, due to their similar chemical properties, the chemical phase analysis method of arsenic has always taken these two minerals as the same phase analysis and determination, and cannot obtain their respective contents. In the research, the orpiment and realgar arsenic ores of Shimen in Hunan Province were taken as the object. The separation conditions of orpiment and realgar samples were studied by single-mineral selective separation technology. The single mineral of orpiment and realgar was leached with 4mol/L ammonia solution and a 35℃ water bath for 6h. The extraction rate of orpiment and realgar was 92.2% and 2.4% respectively. Realgar was leached with sodium hydroxide solution, the extraction of realgar was 75.8%. Due to the spatial structure of realgar being oxidized, the addition of iodine can oxidize it into arsenic oxide that is easily soluble in alkali, increasing the extraction rate to 92.2%. The building of the selective separation conditions lays the foundation for the development of chemical phase separation methods for arsenic ores mainly composed of orpiment and realgar. The BRIEF REPORT is available for this paper at http://www.ykcs.ac.cn/en/article/doi/10.15898/j.ykcs.202208050145.