RECOVERY OF METALS FROM ISHIAGU LEAD-ZINC ORE, NIGERIA

Abstract

The lead-zinc ore sample used in this project was obtained from Ihietutu village near Ishiagu in Ebonyi State and was characterized to determine its chemical and mineralogical compositions. The as-mined sample was crushed, ground and particle size analysis carried out to prepare the ore for compositional analysis concentrate test and metal recovery tests. After, which following gravity concentration by spiral separation, the ore was leached using H2SO4 and Aqua regia at 1:1. The result of chemical analysis using X-ray fluorescence revealed that the ore contained 54.66% Pb, 8.59% Zn, 6.80% W and 2.55% Au and photomicrography from polished section showed that galena grains are interlocked with sphalerite and gangue minerals. The grinding test shows that autogenous grinding method has an average grindability of 58.33 kg/ton/rev and 75.42 kg/ton/rev for the two modes of grinding used, while media assisted grinding method has an average grindability of 77.71 kg/ton/rev and 87.32 kg/ton/rev for both modes. The Results of concentration and metal recovery show that gravity separation using spiral separator gave optimum recovery at +600 μm and most loss at +125 – 53 μm particle size. An average of 88 g and 125 g was leached into the solution after three days for microwave pretreated and as-mined ore. The final leachate contained 150.50 mg kg-1 Pb, 34 mg kg-1 Zn in aqua regia for the as-mined ore, 185 mg kg-1 Pb, 54.25 mg kg-1 Zn in aqua regia microwave pretreated, 137.20 mg kg-1 Pb, 21.50 mg kg-1 Zn in H2SO4 as-mined and 160.40 mg kg-1 Pb, 37.67 mg kg-1 Zn in H2SO4 microwave pretreated. Weight loss during roasting was 3.81%. This study revealed that gold and tungsten are present in the ore.