Abstract
Iron contained in coal fly ash of the Ekibastuz power station is distributed between magnetite and hematite. XRD data showed that ~80 wt % of iron is contained in magnetite and ~20 wt % in hematite. The leaching of iron from CFA by HCl was studied. It was determined that leaching efficiency increased with the increase in hydrochloric acid concentration and temperature. The maximum iron extraction efficiency was 52%. Aluminum is contained in the mullite and was practically not leached. The maximum aluminum extraction efficiency was 3.7%. The kinetics investigation showed that the process of iron leaching was controlled by chemical reaction and diffusion process steps, with an activation energy of 33.25 kJ·mol−1. The aluminum leaching process is controlled by a diffusion process step with an activation energy of 19.89 kJ·mol−1. The reaction order of hydrochloric acid is determined to be 0.9 and 0.23 for iron and aluminum, respectively.
Highlights
IntroductionAt the same time, ~25 million tons of coal fly ash (CFA) are formed with only 2 million tons per year being re-processed
More than 123 million tons of solid fuel are burnt in Russia in thermal power plants.At the same time, ~25 million tons of coal fly ash (CFA) are formed with only 2 million tons per year being re-processed
The purpose of the paper were to removing iron oxides and study kinetics and mechanism of interaction of CFA with hydrochloric acid in the range of temperatures of 25–100 ◦ C
Summary
At the same time, ~25 million tons of coal fly ash (CFA) are formed with only 2 million tons per year being re-processed. Ash dumps occupy large areas within urban land and CFA is transported with high consumption of water (from 10 to 100 m3 /t), while the adjoining territories are contaminated, making them unsuitable for economic use. Coal fly ash contains up to 30% aluminum oxide, making this type of raw material an attractive alternative to bauxites for alumina production [3,4,5,6]. In recent years, acid methods of processing of high-silica aluminum raw materials have been actively developed [10,11,12,13]
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