A. A. Baikov Institute of Metallurgy and Materials Science (Russian Academy of Sciences), Moscow, Russia:

K. V. Goncharov, Senior Researcher, e-mail: goncharov-imet@mail.ru
D. Yu. Kashekov, Research Assistant, Postgraduate, e-mail: deniskashekov@mail.ru
G. B. Sadykhov, Head of Laboratory, Chief Researcher, e-mail: guseyn.sadykhov@gmail.com
T. V. Olyunina, Senior Researcher, e-mail: toliun@yandex.ru

The article presents results of research on extraction of vanadium and nickel from fuel oil ash. The studied ash contains a significant amount of valuable components (7.82% of V₂O₅ and 0.74% of NiO), which makes it a promising raw material for processing. We researched the influence of oxidizing roasting and its duration, the type of charge mixing and the amount of sodium carbonate addition on the level of extraction of vanadium and nickel through consecutive water and sulphuric acid leaching. The article also presents the chemical processes that occur during oxidizing roasting of ash with different amounts of sodium carbonate additions and their influence on the results of extraction of vanadium and nickel. We established that vanadium is generally extracted at the water leaching stage, whilst nickel is extracted only at the sulphuric acid leaching stage this allows for a selective separation of vanadium from nickel. The extraction level of nickel can reach 56.7%, yet it may decrease considerably due to the formation of insoluble nickel ferrite through maximum extraction of vanadium. In the article we offer a schematic diagram of ash processing, where ash is introduced at the wet briquetting stage with addition of 50% of soda. After drying, the obtained briquettes go through 60 minutes of oxidizing roasting at the temperature of 500 оC. We then leach the roasted product in water at the temperature of 80 ^oC for 60 minutes. During this process nearly 82.0% of V₂O₅ goes into the solution, whilst almost all of nickel remains in the solid residue. After that, we extract vanadium from the vanadate solution by sedimentation of ammonium vanadates to obtain a marketable high-purity vanadium pentoxide. Afterwards, we leach the solid residue with a 3% sulphuric acid for 60 minutes to extract nickel. The solid residue, whose mass equals 42.4% of the mass of the initial ash, contains 56.9% of Fe₂O₃, 2.1% of V₂O₅, 1.4% of NiO etc. It poses no harm to the environment and may be further processed as iron-ore or titanomagnetite raw materials at the existing enterprises with extraction of iron, vanadium and, perhaps, nickel.

Our research was carried out with the support of a program of Presidium of RAS (Filing number of Research, Development and Technological Work: АААА-А18-118032690052-5).

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