EQUIPMENT SELECTION FOR OPTIMUM EXPLOITATION OF AJABANOKO IRON ORE DEPOSIT KOGI STATE, NIGERIA

Abstract

The purpose of this research work is to select the most suitable and cost-effective set of equipment in term of type, size and number to exploit the Ajabanoko iron ore deposit using the surface mining method. The perimeter survey of the deposit was carried out, the geological map and isometric projection of the deposit was produced using Global Mapper V12. Block models of the ore bodies were produced and the cross-section at various locations was also produced, the reserve of the deposit was estimated as 62.104 million tons, the average grade 36.63%, and tonnage factor of 0.4. Using the exploration data obtained from National Steel Raw Material Exploration Agency Kaduna, standard reference material and properties of the ore, the mine was design with the following parameters: drill hole diameters 150mm, spacing 6.45m, burden 5.25m, sub-drill 1.8m, stemming 4.8m, bottom charge length 6m, bench height 10 meters, bench slope 65o and bench width 24 meters. The pit slope was evaluated as 21o and the pit limit as 2,997m at super pit, which is the combination of southern and central pit, and 2,954m at northern pit. The pit road network was designed for switchback method and the width of the road is 14m. The mine life was estimated to be 18 years with annual production of 3.5 million tons. The average stripping ratio was 2:1, thereby; 7 million tons of waste must be moved annually. The width of the ramp was determined by the widest dimension of the loading equipment and was 6.620m and total volume of material to be moved during ramp construction would be 4,137 m3. Using the operation manual and catalogue from major equipment manufacturer and analysis of questionnaire developed from operational criteria base on mine activities, various types of drilling, loading and haulage equipment were compared using various criteria; down-the-hole hammer drill was selected for drilling. Three potential loading – haulage system alternative to meet the optimum production were evaluated by fussy-TOPSIS decision making technique using two strategic factors, namely cost and operational/technical factors. These are loader-truck, shovel-truck and shovel-truck-belt conveyor system, out of which Shovel-truck system was selected. Caterpillar model was selected for loading and haulage equipment while Atlas copco was selected for drilling equipment. Three down-the-hole hammer drill, five shovels with capacity of 7.6 m3 each and eleven dump truck of 113 tons capacity are required. The economic evaluation was done by discounted cash flow technique using net present value (NPV), payback period and internal rate of return (IRR). The annual revenue at the product price of $68.80/ton was $0.24 billion, capital cost was $4.3 million and annual operating cost was $33.72 million and the discount cash flow for the 18 years of operation were positive with a payback period of 13 years and internal rate of return of 4%, working at discount rate of 15%, depreciation rate of 27.5% and tax rate of 35%.