Catalytic effect of alkali chlorides on carbothermic reduction of pre oxidized ilmenite

A computer monitoring thermogravimetric system was used to study the effect of alkali chlorides(MCl, M=Li, Na, K and Cs) on the carbothermic reduction of pre oxidized ilmenite in the course of a linear rise in temperature from 600 ℃ to 1 000 ℃. The experimental results indicate that all the alkali chlorides can speed up the reduction process of pre oxidized ilmenite, moreover, KCl is the most effective catalyst of the chlorides, while the catalytic effects of LiCl and CsCl are relatively weaker. It seems that the catalytic mechanism of LiCl is different from those of the other alkali chlorides. The cross sectional morphology of the partially reduced pre oxidized ilmenite particles and the distribution of potassium ions within them were examined by means of scanning electronic microscopy and electronic probe microanalysis, respectively, which shows that the reduction proceeds topochemically and the alkali ion enriches at the periphery of the particles.[

Catalytic Mechanism of KCl during Carbothermic Reduction of Pre-Oxidized Ilmenite

As alkali additive,KC1 catalyzes effectively the carbothermic reduction of pre-oxidized ilmenite,and the catalytic effect becomes more remarkable as the amount of KC1 increases.During the carbothermic reduction,the gaseous product consists mainly of CO,and the partial pressure of which increases with reaction temperature.The EPMA and XPS of the partially reduced ilmenite ore and that of the used graphite as reductant showed that the potassium ions enter both ilmenite particles and graphite powders during reduction.The above-mentioned phenomena result in the distortion of ilmenite and carbon structure by potassium ions and reaction activity of carbon and ilmenite was enhanced.As a result,the overall carbothermic reduction was catalyzed by KC1.

Dechlorination Behavior of Mixed Plastic Waste by Employing Hydrothermal Process and Limestone Additive

The usage of plastic-impregnated waste derived solid fuel in conventional combustor is hindered by many technical factors, especially its organic chlorine content. In this paper, experimental study of hydrothermal treatment on mixed plastic waste using the mixture of polypropylene, polystyrene, polyethylene and polyvinyl chloride （PVC） has been performed to observe the dechlorination effect of hydrothermal treatment on the waste. The system was generally applying saturated steam at around 2.4 MPa in a stirring reactor for about 90 minutes. After undergoing the process, the organic chlorine in treated plastic waste was reduced to 1,700 ppm level while the inorganic chlorine content was increased, suggesting an organic chlorine conversion phenomenon to inorganic chlorine, accompanied with low pH due to dehydrochlorination process. Additional limestone （Ca（OH）2） in subsequent experiment showed that the similar phenomenon was occurred but with higher pH and lower chlorine content in the condensed water, suggesting the production of inorganic salt rather than hydrochloric acid. Laboratory scale experiment was also performed to confirm the dechlorination phenomena especially for PVC, and the result showed that the main parameter which affected the dechlorination phenomena was the amount of water in hydrothermal process rather than limestone addition. It is suggested that a combination ofhydrothermal process and alkali addition would produce a low-chlorine solid product from plastic waste, promoting its usage as alternative solid fuel.