No abstract

No abstract

No abstract

No abstract

The main purpose of this study is to characterize and separate antimony from a stibnite concentrate through a low-temperature sulfur-fixing smelting process. This article reports on a study conducted on the optimization of process parameters, such as flux and zinc oxide weight percentage, in charging, smelting temperature, smelting duration on the antimony yield, resultant crude antimony grade, and sulfur-fixing rate. A maximum antimony recovery of 97.07 pct, crude antimony grade of 96.45 pct, and 98.61 pct sulfur-fixing rate are obtained when a charge (containing 63.20 wt pct of flux and 21.30 wt pct of stibnite, a flux composition of W NaOH =W Na 2 CO 3 = 10/147, where W represents weight, and more than 10 pct of the stoichiometric requirement of zinc oxide dosage) is smelted at 1153 K (880°C) for 120 minutes. This smelting operation is free from atmospheric pollution because zinc oxide is used as the sulfurfixing agent. The solid residue is subjected to mineral dressing operation to obtain suspension, which is filtered ultimately to produce a cake, representing the solid particles of zinc sulfide. Based on the results of the chemical content analysis of as-resultant zinc sulfide, more than 90 pct zinc sulfide can be recovered, and the recovered zinc sulfide grade can reach 66.70 pct. This material can be sold as zinc sulfide concentrate or roasted to regenerate into zinc oxide.

This study proposes an innovative and environment-friendly method for recycling spent lead-acid batteries without SO2 generation. Iron-containing waste was employed as a sulfur-fixing agent to retain sulfur as ferrous matte, which eliminated the generation and emissions of gaseous SO2. This work investigated the thermodynamic and experimental feasibility and conversion mechanism of the method, and evaluated its industrial applicability. A bench-scale test showed direct recoveries of 93.5 % and 97.7% in crude lead and ferrous matte for lead and sulfur, respectively. The phase transformation mechanism study indicated that metallic lead from the lead paste was extracted mainly through the sequence of PbSO4 / → PbS 3 4 → PbO / → . Sulfur in PbSO4 was thus first transferred to PbS and finally fixed as FeS. An industrial-scale pilot campaign was also conducted to confirm the feasibility and reliability of the new process.

No abstract

Abstract:A new process for one-step extraction of antimony in low temperature from stibnite concentrate by reductive sulfur-fixation smelting in sodium molten salt, using iron oxide as sulfur-fixing agent, was presented. The influences of molten salt addition and composition, ferric oxide dosage, smelting temperature and duration on extraction efficiency of antimony were investigated in details, respectively. The optimum conditions were determined as follows: 1.0 time stoichiometric requirement (α) of mixed sodium salt (α salt = 1.0), W NaCl :W salt = 40%, α Fe 2 O 3 = 1.0, W coke :W stibnite = 40%, where W represents weight, smelting at 850˝C (1123 K) for 60 min. Under the optimum conditions, the direct recovery rate of antimony can reach 91.48%, and crude antimony with a purity of 96.00% has been achieved. 95.31% of sulfur is fixed in form of FeS in the presence of iron oxide. Meanwhile, precious metals contained in stibnite concentrate are enriched and recovered comprehensively in crude antimony. In comparison to traditional antimony pyrometallurgical process, the smelting temperature of present process is reduced from 1150-1200˝C (1423-1473 K) to 850-900˝C (1123-1173 K). Sulfur obtained in stibnite is fixed in FeS which avoids SO 2 emission owing to the sulfur-fixing agent. Sodium salt can be regenerated and recycled in smelting system when the molten slag is operated to filter solid residue. The solid residue is subjected to mineral dressing operation to obtain iron sulfide concentrate which can be sold directly or roasted to regenerate into iron oxide.