Physicochemical Analysis of the Wastes From the Kuzbass Heat and Power Enterprises for the Determination of Optimal Recycling Approaches

The problem related to processing and disposal of ash and slag waste from thermal power facilities has not been solved in Russia as a whole, and particularly in Kuzbass. In the present work, we studied ash and slag (slag, fly ash from Kemerovo and Belovo heat plants, and Kemerovo power plant) and related wastes (cake and ore from the enrichment plant) from the enterprises of Kuzbass using physicochemical methods to assess the optimal ways of their processing. X-Ray diffraction analysis has shown the presence of quartz in all the studied wastes, carbon-like phases in rocks and cake, and vitreous phases in all slags and the vast majority of fly ash samples. The materials were analysed by atomic emission spectroscopy with inductively coupled plasma after autoclave preparation of the sample with a mixture of nitric and hydrochloric acids. X-Ray fluorescence analysis was performed for rocks and cake. Element content in samples, assessed from atomic emission analysis data, correlates with the data of X-ray fluorescence analysis. Fly ash, ash and slag wastes differ from each other in composition: fly ash is characterised by lower magnesium and iron content. It is shown that glass formation in ash and slag at high combustion temperatures complicates the acid extraction of elements. The method of acid leaching with nitric acid followed by precipitation with a solution of ammonia and oxalic acid was tested. Rare earth elements are observed to concentrate in the fraction of insoluble hydroxides, where aluminium prevails as the major element; in particular, europium is concentrated up to 144 g/t. Low calcium content, high silicon and aluminium content allowed us to propose manufacture of silicate products with the possibility of isolating rare and rare earth elements as the main way of processing the wastes from the enterprises of fuel and energy complex of the Kemerovo Region (Kuzbass).