Sulfur Extraction from Elemental Sulfur-Bearing Materials

摘要

The Federal Bureau of Mines devised two high-temperature solvent extraction techniques to recover elemeental sulfur from a leached residue generated from leaching a lead concentrate with ferric chloride and sodium chloride. The procedures are similar except for the mechanisms by which the sulfur is extracted from the residue, and the temperatures to which the extractants are cooled to induce sulfur solidification. One method uses an organic liquid carrier to melt sulfur out of the residue, and the other uses an organic liquid for its properties as a solvent for sulfur. In the carrier procedure, leached residue and carrier were mixed and heated at atmospheric pressure to above the metling point of sulfur. The hot slurry was filtered to separate the solids from the filtrate, which was a mixture of the carrier and liquified sulfur. The filtrate was cooled to 110 C and filtered again to separate the solidified sulfur product from the carrier. Sulfur recovery was 61 pct and purity was at 99.9 pct. In the carrier-solvent procedure, the sulfur-loaded filtrate was cooled to 20 C rather than 110 C to precipitate dissolved sulfur. Sulfur recovery was 93 pct and purity was 99.9 pct. For both procedures, the reclaimed extractants were suitable for resuse.