Volatilization Behavior of Arsenic from a Hematite Ore During Non-isothermal Heating in Argon Atmosphere

Abstract

Due to the increase in steel production in the world and the depletion of high-grade ore resources, there is a need to investigate the use of low-grade ores that includes arsenic-containing iron ores. Arsenic (As) is volatile, and As removal from the ore by roasting or sintering is limited because of many chemical interactions with other metallic elements within the ore. In this experiment, arsenic volatilization was thermodynamically investigated and the volatilization characteristic from a hematite ore in argon atmosphere was investigated in the temperature range of 298-1623 K using the thermogravimetric-differential scanning calorimetry (TG-DSC) and the vertical tube furnace. The percentage weight loss and volatilization rate were evaluated by raising the temperature non-isothermally at 10 K/min in the TG-DSC and the vertical tube furnace in an argon atmosphere. X-ray diffraction (XRD) analyses were done on the cooled and crushed samples to identify the change in phases after heating to temperatures above 1273 K. Electron probe microanalysis analyses were used to verify the possibility of existence of some of the phases identified by XRD. The results showed that the percentage weight loss of the pellet increased with increase in temperature. Metallic element distribution after non-isothermal heating to temperatures above 1273 K showed that As was likely to be highly concentrated in the same area as Ca, Si, and Al. This was in agreement with the XRD results and the thermodynamic predictions, which showed that 3CaO center dot 2As(2)O5(s) and the AlAsO4(s) were likely to be the most stable As-containing phases even at temperatures of about 1623 K. The volatilization of all volatile material from the ore depends on the bonding energy holding the volatile matter in the pellet. [GRAPHICS] .