Thermal and X-ray phase analysis of the “lead-containing dust–sulfur” system

Abstract

The study of phase transformations in the system” lead-containing dust – sulfur ” is actual, as in many pyrometallurgical processes lead-containing dust is formed. The accumulation of such industrial waste causes ecologically stress on the environment. The sulfur is select as a sulfiding agent due to the problem of its utilization in the oil industry. The article covers the possibility of lead dust sulfiding with technical sulphur. Thermal and x-ray phase analysis of mixtures of lead dust and elemental sulfur in various ratios was carried out. Thermal analysis was performed on a Q-1000/D derivatives without air access, which was achieved by blocking crucible with the analyzed samples by aluminum oxide, in the temperature range 20-1000 ° C, heating mode – dynamic (dT/dt = 10 deg/min), reference substance – calcined Al₂O₃. X-ray diffraction analysis was performed on an automated diffractometer DRON-4 with Cu_Кa-radiation and β-filter. In the studied system, the main temperature intervals, wherein sulfur actively reveal itself, are 60-220 and 220-360 °C. The state of the system beyond 450 °C is clear from the physical properties of the lead dust. Rising of sulfur concentration increases the visibility of the peak on the DTA-curve associated with polymorphic transformation of lead oxy-sulfates and activation of sulfide formation processes. The increase in the intensity of the effects of sulfur direct interaction with the components of the charge reflects the difference in sulfur concentrations in the compared samples. On the other hand, the increase of sulfur content in the composition of the sample leads to some attenuation of the physical properties (melting) of lead oxy-sulfates. Thus, the increase of the sulfur content in the charge more strongly stimulates the development of sulfidization process in the system, which takes place within 140-300 °C. Within the same next stage of thermal manifestation, sulfide formation in the system and activation of the lead compound interaction is directly related to sulfur. The scientific and practical significance of the investigation is in the possibility of the use of technical sulfur, waste oil industry for sulfiding lead dust.