ENMIN 5100 Mine Power Supply and Drainage Mine Drainage Design Task Answer all questions (worth 30% of total assessment) Due Date 31 December 2016 If required it may be assumed that g = 9.81 m/s2, Density of water = 1000 kg/m3, You are a mine planning engineer at a medium sized operation producing 1.5 mtpa of coper ore at 3% Cu. The mine was originally designed using a bench height of 15m. Footwall benches were 15 m wide to give a slope angle of 45°, but on the hanging wall side alternate benches are only 10m wide to produce an angle of about 50°. You are required to design a drainage and pumping system to deal with the mine water for the next 10-15 years based on the data in the following sections. As the mine grade is low and power costs are high every effort should be made to minimise the operating costs of the pumping system. Describe your proposed drainage and pumping system with the aid of diagrams where required and explain the general philosophy behind the system. Detail and assumptions made and make comments and conclusions as required. Data Mine water Ground water: currently averages 1,000,000 litres/day and is expected to increase at a rate of 5% per year as the mine deepens. Mine water: averages 50,000 l/day with small variations in use on an hour by hour basis. Water Quality: Run of mine water is expected to be slightly acidic due to the formation of sulphuric acid from sulphides within the rock Rock properties: SG of 2.9 for all rocks. Hanging wall and ore have moderate strength, footwall is very strong.Mine Section Rainfall: the average annual rainfall s 740 mm, the average monthly figures are as follows January 10mm February 10mm March 40mm April 60mm May 80mm June 100mm July 110mm August 120mm September 90mm October 60mm November 40mm December 20mm Based on measurements in the locality the maximum rainfall intensity recorded over the last 50 years is as indicated below and needs to be accounted for: Storm duration (hours) Intensity (mm/hr) 2 40 4 25 8 15 12 12 16 10 20 9 24 8 36 6 48 5