The project aims to introduce a process that will add value to a low grade laterite ores thus reducing the direct shipment cost of Nickel Laterite ores, create more jobs and additional revenue for the country.
For Nickel Laterite ores especially the low grade ores (less than (1.8%Ni), Reduction sintering can be employed to produce an acceptable grade level feed to the Electric Arc furnace as well as marketable grade Iron and Nickel concentrates.
Metallurgical test works include agglomeration of the samples that were mixed with fine charcoal and lime at various ratios for reduction sintering using a rotary kiln. The kiln is a cylindrical vessel (157cm long) inclined slightly to the horizontal which rotates slowly about its axis (9cm inner diameter). The sintered materials were crushed to about ½ inch and %Fe, %Ni and %Cr2O3 were checked. Crushed material is subjected to dry magnetic separation using high intensity magnet (roughing concentration). %Fe of both the non magnetic and magnetic materials will be assayed. Both the magnetic and non magnetic material are further ground and subject again to series of wet magnetic separations of varying magnetic intensities to attain the desired %Fe. Tailings of the final magnetic separations were fed to a 2 ft by 4 ft gravity concentration table. Concentrate of which were assayed for %Fe and %Cr2O3 and the gravity tailings will be regarded as final tails for construction purposes.
A consistent and appreciable upgrade on reduction sintering were achieved on a sixty (60) minute reduction time with 15% coal addition by weight and with water quenching right after reduction sintering. Iron soars to 59.21% from initial grade of 47.62% Fe. Nickel also increased 0.42%. Sintered products were upgraded using magnetic and gravity separations. Upgraded product yielded an assay of 62.23% Fe and the Chromite is increased by 5.93% Final concentrates yield for Nickel and Iron combined is 60% and for Chromite is at 8%.
Emission levels of the reduction sintering process tests will be conducted to determine if such levels meet the current national environmental regulation standard limit as specified in the 'National Emission Standard for Source Specific Air Pollutants'.
Bernardo V. Bitanga and Rey V. Perucho
Metallurgical Technology Division
Mineral Processing Research and Development Section