Thermodynamic Modeling of Arsenic in Copper Smelting Processes

Abstract

Published data on the activity coefficients of arsenic in liquid copper, matte and, slag have been reviewed, assessed, and used in the development of thermodynamic databases for solution models of melts. The databases were validated against the literature data on the equilibrium distribution of arsenic between the matte and the slag. The models and databases were used in investigating the effects of matte grade, slag chemistry, SO 2 partial pressure, arsenic loading, and temperature on the equilibrium distribution of arsenic between the melts and gas phase during copper smelting and converting. The results obtained show that the continuous smelting processes operates close to equilibrium between condensed phases with most arsenic reporting to the gas phase. A comparison of the batch and continuous converting processes showed a considerable difference with respect to the elimination of the arsenic from condensed phases. These results indicate batch processes to be more efficient in the removal of arsenic through the gas stream.

Reaction Mechanism and Distribution Behavior of Arsenic in the Bottom Blown Copper Smelting Process

“…However, the dominant arsenic compound in the concentrates is orpiment (As 2 S 3 ), therefore, in this study the arsenic species were simplified to orpiment (As 2 S 3 ). Based on research results by other scholars [7,8,18], in copper smelting system at high temperature, the main arsenic species in the gas phase are AsS (g), As 2 (g), and AsO (g). Arsenic exists in slag predominantly as As 2 O 3 (l), and in matte as As (l).…”

“…Tiny arsenic is oxidized into As 2 O 3 , and most arsenic exists in form of As, AsS, and AsO. Because the vapor pressures of As, AsS, and AsO are higher than As 2 O 3 at high temperatures (around 1200 • C) in the copper smelting system [5,7,8], most arsenic is volatilized into the gas phase in form of As 2 (g), AsS (g), and AsO (g), and a small amount of the arsenic carries into the slag and matte. However, in the flash smelting process, oxygen-enriched air, concentrate particles, and fluxes enter through a single burner in the reaction shaft, and most oxidation takes place while the particles fall toward the settler, as shown in Figure 6b.…”

“…The phenomenon may be explained by the following reasons: the activity coefficient of As in matte decreases with an increasing matte grade, and higher grade matte has a higher affinity for arsenic and hence reduces the activity and vapor pressure of arsenic [7,18]. The activity of sulfur in mattes also decreases with increasing matte grade, causing lower partial pressures of S 2 and a lower degree of volatilization of arsenic as AsS at higher matte grades [7,18]. So high matte grade is not helpful in removing arsenic.…”

“…Arsenic, a toxic and carcinogenic element [1][2][3][4], is often associated with copper concentrates [5][6][7]. In the smelting process of copper sulfide ores, arsenic could carry into gas, slag, and matte phases [7].…”

“…In the smelting process of copper sulfide ores, arsenic could carry into gas, slag, and matte phases [7]. Severe environmental pollution and serious harm to people's health would be caused by arsenic emissions, especially As 2 O 3 .…”