Thermodynamic modeling of metal reduction from melts of high-iron oxidized nickel ore

Abstract

Ferronickel, currently obtained from oxidized nickel ores in various aggregates, contains 5 – 20 % Ni. The possibility of obtaining rich (about 70 % Ni) ferronickel from a melt of silicate-nickel ore during its treatment with reducing gas has been experimentally shown. Features of reduction of high-iron variety of nickel ore from the Serovskoye deposit with carbon monoxide are considered using the methodology of metallurgical processes thermodynamic modeling, adapted to open systems. For the calculations, the following composition of the oxide melt was adopted, mass. %: 60,4 Fe 2 O 3 ; 1,4 NiO; 0,14 СоО; 5,8 Аl 2 O 3 ; 17,0 SiO 2 ; 4,2 MgO; 11,1 CaO. The simulation was carried out at a pressure of 0.1 MPa, at amount of carbon monoxide in one portion – 10.6 dm 3 /kg and at temperature of 1673, 1723, 1773 K. During the calculations, dependencies were found that bind the content of nickel (C Ni ), iron (С Fe2O3 , C Fe3O4 , C FeO ) and cobalt (С СoО ) oxides in the oxide melt and metals in the alloy (С Ni , С Fe , С Co ) as well as the degree of their transition to the metallic state (φ Ni , φ Fe , φ Co ) with the amount of introduced gas. Contents of the components in a single portion of the reduced metal were determined. In the temperature range of 1673 – 1773 K and the introduced amount of CO equal to 190 dm 3 /kg, the content of Fe 2 O 3 in the oxide melt is 0,17 – 0,12 %; Fe 3 O 4 – 1,77 – 1,05 %; FeO – 55,6 – 56,5 %; NiO – 0,026 – 0,037 % and CoO – 0,061 – 0,068 %. With a degree of nickel reduction of 98 %, degree of iron reduction is 5 %, and degree of cobalt reduction is 56 – 61 %. An alloy formed from reduced metals contains about 30 % Ni, 63 – 65 % Fe and 2 % Co. Thus, the possibility of selective reduction of nickel and cobalt under certain conditions is shown. The data obtained are significant for substantiating the parameters of technological processes for the production of ferronickel from high-iron oxidized nickel ores.