High-Temperature Volatilization Mechanism of Stibnite in Nitrogen-Oxygen Atmospheres

Abstract

The volatilization of stibnite (Sb 2 S 3 ) in nitrogen and mixtures of nitrogen-oxygen was investigated in the temperature range 973 K to 1423 K (700°C to 1150°C). The overall volatilization reaction study was carried out using a thermogravimetric analysis technique under various gas flow rates. The results indicated that in an inert atmosphere, stibnite can be volatilized most efficiently as Sb 2 S 3 (g) with a linear rate up to about 1173 K (900°C). At temperatures above 1223 K (950°C), stibnite decomposes to antimony and sulfur gas, impairing the antimony volatilization. For linear behavior in nitrogen gas, kinetic constants were determined, and an activation energy of 134 kJ/mol was calculated for the volatilization reaction. However, in the presence of oxygen, antimony can be volatilized efficiently as valentinite (Sb 2 O 3 ) at low oxygen concentrations (approximately 1 to 5 pct) at approximately 1173 K to 1223 K (900°C to 950°C); otherwise, at higher partial pressures of oxygen, the volatilization of antimony is limited by the formation of nonvolatile cervantite (SbO 2 ). In highly oxidizing atmospheres, a high vaporization of antimony could be achieved only at temperatures higher than 1423 K (1150°C) where cervantite becomes unstable and decomposes into SbO(g) and 0.5O 2 (g).

Kinetics of stibnite (Sb2S3) oxidation at roasting temperatures

“…Recently, Padilla et al [6] carried out an isothermal study of the volatilization of stibnite in nitrogen-oxygen atmospheres in the temperature range of 700 to 1150 °C and they were able to determine the reaction mechanism in this temperature range. Their results indicated that in the presence of oxygen, antimony could be volatilized efficiently as Sb20 3 in the temperature range of 900 °C to 950 °C in a gas phase with 1 to 5% oxygen.…”

Thermodynamic and kinetics analysis of the sulfur-fixed roasting of antimony sulfide using ZnO as sulfur-fixing agent

“…As shown in DSC curve, there was an exothermic peak at 782.47 K and an endothermic peak at 901.63 K. According to the TG curve, we can see that the reaction has two stages of weight losses. The losses rate of the weight for the first stage is 2.36%, which was caused by the volatilization of the raw mixture at the exothermic peak of 782.47 K, In the second stage, the weight losses rate was 15.78% might cause by the volatilization of Sb 2 O 3 and Sb 2 S 3 at 901.63 K, which is close to the melting-point of antimony oxide of 929.15 K. Meanwhile, R. Padilla once investigated the volatilization of antimony sulfide and verified that it would thoroughly volatilize at the temperature ranges of 873 K to 1073 K [4], so this 20% weight loss of mixture is impossible by volatilization of Sb 2 S 3 . In order to find out the phase composition of the product in two weightlessness stages, the XRD patterns of the samples obtained at different temperatures are shown in Fig.2(b).…”

“…Most of the resources of antimony known in the world are distributed in China, accounting for 80% [1][2]. At present, the main mineral for producing antimony is stibnite (Sb 2 S 3 ) and jamesonite (Pb 4 FeSb 6 S 14 ) [3][4][5]. The traditional method for the production of antimony is volatilization smelting followed by reduction smelting [6][7], which consists of two steps: oxidative volatilization of Sb 2 S 3 and reducing smelting of Sb 2 O 3 [8][9].…”

Antimony production by carbothermic reduction of stibnite in the presence of lime

“…or the product Sb since the S b02 is non-volatile at 1073K. Padilla et al [16] in their study of volatilization of stibnite in nitrogen atmospheres found a constant volatilization rate of Sb2S, at 1073. K, which is consistent with the Figure 2.…”