Influence of low-temperature calcination of coal ash with alkaline agents on efficiency of valuable component recovery

The article describes the studies into recovery of aluminum and valuable admixtures from dry ash from Reftinskaya Water Power Plant. The ash source is high-ash coal from Ekibastuz coal basin. The test ash contains aluminum (21% Al2O3), as well as iron, cobalt, zircon and rare earths. High content of silicium (27%), associated with aluminum, zircon and some rare earths, necessitates the use of the thermochemical method to dissociate this manmade material. For enhancing efficiency of integrated recovery of aluminum and other valuable components from the ash, it is proposed to implement preliminary low-temperature calcination of the ash with alkaline agents. Using the modern analytical techniques—optical microscopy, combination scattering spectroscopy and thermal analysis, it is shown that calcination favors structural weakening of some leaching-resistant minerals. It is found that production of readily milled and slaking cakes which ensure enhanced leaching efficiency needs that the mass ratio of the ash and NaOH is 1:1 and lower. The experimental studies of calcination of tailings after magnetic separation of ash with sodium hydroxide reveal the effective calcination mode at 350 ºC: it increases aluminum recovery by 1.8 times (from 45.4 to 80.9%) in acidic leaching by combination of agents owing to transition of leaching-resistant minerals to better soluble material.

Lavrinenko A. A., Kunilova I. V., Gol'berg G. Ju. Influence of low-temperature calcination of coal ash with alkaline agents on efficiency of valuable component recovery. MIAB. Mining Inf. Anal. Bull. 2023;(10):104-121. [In Russ]. DOI: 10.25018/0236_1493_2023_ 10_0_104.

A.A. Lavrinenko¹, Dr. Sci. (Eng.), Chief Researcher, Head of Laboratory, e-mail: lavrin_a@mail.ru, ORCID ID: 0000-0002-7955-5273,
I.V. Kunilova¹, Cand. Sci. (Eng.), Senior Researcher, e-mail: kunilova_i@ipkonran.ru, ORCID ID: 0000-0002-7775-085X,
G.Ju. Gol'berg¹, Dr. Sci. (Eng.), Leading Researcher, e-mail: gr_yu_g@mail.ru, ORCID ID: 0000-0002-7968-3144,
¹ Institute of Problems of Comprehensive Exploitation of Mineral Resources of Russian Academy of Sciences, 111020, Moscow, Russia.

A.A. Lavrinenko, e-mail: lavrin_a@mail.ru.

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