1.0 Project Description
1.1 Property
The Taylor Project lease owned by Fed Resources Pty Ltd is located approximately three hundred kilometers, by road, from a suitable port facility, Port Steve (see Figure 1). Fifteen kilometers to the west is a disused railway that connects the nearby pastoral village Glendale to Port Steven. Infrastructure in the area is minimal, although Glendale is connected to grid power by a small run-down substation. Local government has offered large subsidies for services to encourage development in the area and has indicated that refurbishing and upgrading the small power plant in Glendale would be of much benefit to the local community. To make the project economically viable and to ensure value to shareholders, Fed Resources has calculated that a limit of 3.65 Mt per year good cooking coal must be produced for the first 5 years of the project until capital funds become more available and production can be increased.
1.2 Mineralisation
The deposit is coal seam of averaging 7m in thickness; its dip angle is on average 25 degree till the depth of 1000 meter then turns zero degree for another 30 m where the seam dies out rapidly; the length of the seam along the strike is 900m. This deposit is part of a tropical coal basin of Late Permian age of fluviatile and lacustrine origin, with good coking coal. The delineated reserves, to date, total around 500 Mt. Overburden is a typical basin sedimentation stratigraphy the deposit outcrops at the surface, and all bedding is nearly parallel to the coal seam. An idealised view of the ore body is show in Figures 2, 3 and 4 below.
1.3 Deposit Value
The current contract price for coking coal is hovering around A$100/tonne. The total apparent value of the 500 Mt deposit is therefore A$50,000,000,000 (A$50 B). If the mining company is considering selling the deposit before mining, an estimate of 5% of the total value can be made to provide an indication of the as-is saleable valuable of the deposit, A$2,575,000,000.
The potential profit for the deposit is discussed later on in section XX XX
1.4 Mining
Open pit mining will be used to extract the coal seam due to the ore body’s outcropping nature, the surrounding host rock’s strength and reduced cost of mining.
Fed Resources has provided the requirement for an initial stripping ratio of 4.8:1 to make the project economically viable at current coaking coal prices.
1.5 Infrastructure and Services
1.51 Water
Fed Resources have obtained approval to make complete use of the medium sized lake Werringa to the north east of the lease, see Figure XX below. A 2 km pipeline and pumping system has already been installed to transfer the fresh water from the lake to the project site in preparation for earthworks.
1.52 Power
The Glendale power substation (Figure 4 below) has been servicing the local community for the last 15 years. Poor maintenance and minimal government funding has meant that the substation is already at its output capacity and is in poor working order.
Figure 4 Glendale Substation
Local government is keen to have the substation refurbished and upgraded to support the growing community and as such have offered large subsidies to Fed Resources if they are able to undertake the work while extending the power to the mining lease. The location of the substation is show in Figure 5 below.
A cost estimate of installing a medium voltage (33kV) SWER line between the Glendale substation and the project lease has been received from the Port Steven power company. The installation will require 75 new power poles, one every 200 m, over the 15 km distance. At approximately $10,000 per pole, the new power line is expected to cost around A$750 k. The power company has quoted on the substation upgrade and refurbishment of the Glendale substation, to achieve a 150 kV substation output the cost is approximately A$1.25 mil. A 25 kV substation, Figure 5 below, has already been sourced from a previous Fed Resources mining project. This substation will be adequate to supply the onsite offices and amenity facilities with capacity to run a number of small electrical drill rigs if required.
At approximately A$2 mil to get power on the project site, the local government has offered up to A$600 k to help fund the upgrade, the remaining A$ 1.4 mil will need to be funded by Fed Resources . A net present value comparison of getting electricity on site compared to diesel generation was undertaken and indicated that the relatively large capital cost of the power distribution work will pay for itself within 4 years.
1.53 Rail
The Glendale railway connects Glendale to the city of Port Steven via a 310 km track that directly links to Port Stevens docks. The railway was previously used to transport granite sand from a small mine near Glendale to Port Steven. The City of Glendale still has haulage carriages and has indicated that they are keen to lease the equipment to Fed Resources. A new railway link will need to be established between the project site and Glendale, early estimates have indicated the link will cost approximately A$400 k and could be established within months. It is recommended that this link be established as soon as possible as it will provide cost effective ore transport to the Port as well as being able to transport the workforce and supplies from Glendale to site.
Figure 6 Glendale Railway
1.54 Climate
Semi-arid conditions are to be expected, reasonable rainfall events are experience during the winter months. The climatic conditions show in Table 1 below are sourced from the Glendale weather station and are a very good indication of conditions to be expected onsite. Wind is generally confined to small storms in winter and no flooding has been experienced in the area in recent history.
The Taylor Project lease site has been used as farming land in the past and has been extensively cleared. Minor stripping works will be required to fully expose the coal seam and overburden rock below. Figure 7 below shows the typical site conditions.
Figure 7 General site conditions
4.0 Mine Design
4.1 Excavation Plan
In order to determine the dimension to be used for laying out the haul road, catch benches and mining equipment clearance area, a sensitivity analysis was performed on varying final pit slope to determine the total material movements and consequently, varying stripping ratios. The analysis uses final pit slope angles varying 60° to 70°, as this is the range of angles that would best suit the shape of the ore body. For the purposes of the project, a flitch height of 7.5m has been assumed for each pass. The flitch height has been doubled such that the safety berm will be only left on every second bench, thus the bench height being 15m. The 7.5m has been chosen as a trade-off between bulk mining practices and the ability to grade the ore body. This is a very crude method of conducting a first pass on the total material movement and applies a single angle to the wall to give a total calculation for the area, which are then used to determine volume and tonnages for the pit. The method employed does not take into account catch berm, haul roads or the minimum dimensions required for mining equipment; however it does provide a good point to determine the size of equipment required to meet the annual material movement requirements.
4.2 Geometrical Considerations
4.2.1 Overall Slope Angle
The overall slope angle in an open pit mine is a very important consideration when designing the mining operation. The measurement of the overall slope angle is done from the bench toe at the bottom of the mine to the bench crest at the top of the mine. This is the angle upon which the walls of an open pit mine stands. The determination of this angle takes into consideration many factors. Some of these factors include water conditions, rock strength, and the geological structures in the site of the mine. The width of the haul road that is constructed on the slope and the grade are also factors that affect the overall slope angle. The recommended overall pit slopes range between 40o and 43o. This is an indication that the controlling factor of the design of the open pit design is the strength of the rock mass. This is also due to the fact that haul ramps will be designed into the walls of the pits in order to flatten the overall slope of the open pit. The requirement for this angle range is the use of controlled blasting techniques and measures to depressurize ground water (Read & Stacey, 2009).
4.2.2. Slope, bench and ramp design
Bench scaling is very important in the design of this project. The benches will be kept clear with their faces being maintained on a regular basis so that they are functional throughout the entire mining operation. Scaling of the benches will be performed after blasting is done in those areas which are still accessible. The stability of the overall slope is also an important consideration. In anticipation of high water pressure in the walls of the open pit, depressurization measures that include perimeter pumping wells, surface ditches and horizontal drains will be installed. The recommendation for the inter-lamp slope is an angle of 45o. The recommended width for the ramp is eight meters. This is in order to intercept any rock falls or raveling.
4.3. Mine power & drainage design
The areas adjacent to the mine have inland lakes. Additionally, some rain is expected throughout the year. There are two months in the years when the rainfall expect is going to be significant to the operations in the mine. In this regard, the drainage design in the mine is pegged in the need for wall stability. In anticipation of high water pressure in the walls of the open pit, depressurization measures that include perimeter pumping wells, surface ditches and horizontal drains will be installed. Vertical pumping wells will also be installed in order to evacuate any surface run off or underground water that might settle at the bottom of the mine. Mine power will be gotten from electricity as has been discussed earlier (Read & Stacey, 2009).
4.4. Main equipment selection and matching
The selection of the main equipment in an open pit mining is of striking significance as it influences the operating cost by between 40 and 60%. For site cleaning and preparation purposes, front-end loaders, scrappers and bulldozers will be required. For the purposes of drilling, down-the-hill drill, jack hammer drill, rotary percussive drill, all hydraulic drill, auger drill, rotary drill and wagon drills will be required. For the purposes of overburden removal, bucket-wheel excavators, shovels, front-end loaders and draglines will be required.
Coal loading will be done using shovels, hydraulic excavators and front-end loaders. Transportation will be done using conveyors, aerial ropeway, trucks and dumpers. Reclamation of the land will be done using tracked dozers scrapers, reclaimers, stackers, bucket-wheel excavators, bridge conveyors and back filling using the equipments that was used for the transportation of overburden. Other for miscellaneous purposes include mobile hoppers, rippers, spreaders, explosive vans, welding sets, crushers, graders, cable cars, pipe layers, lubrication trucks, generators, service trucks, compressors, track shifters, shiftable spoils conveyors, cable drum trailers, water trucks, fire tracks, ambulances, trenchers and transfer Hooper points (Gokhale, 2011).
4.5. Operational design 4.5.1. Detail Production requirements including a full description of the method selected
The mining technique employed in this technique is the open pit mining. This is a surface mining technique where the mineral is extracted from the earth through an open pit. The choice of this method is appropriate because the mineral deposit is near the surface. Additionally, the overburden is considerably thin. As discussed under the location of the site, the structural material in the area is unsuitable for methods like long wall tunneling. In the extraction of the minerals, benches amounting to vertical levels in the open pit will be constructed. The walls of the pit will elevate at an angle ranging between 40o and 43o in order to mitigate the danger of falling rocks. The production requirements will be dependent on the available and mineable coal reserves, the lengths of the strikes and dips, surface structures, HEMM configuration and the linkages. 4.5.2. Number of production units required.
The number of production units required is dependent on the volume of coal in the mine. Volume of the coal is calculated by multiplying the quarry floor area by the cumulative thickness of all the seams making the mineral ore. However, the coal deposits in the region have already been valued at 50,000,000,000 Australian dollars. With the value of one tone of coal estimated at 100 Australian dollars, the volume of coal in the mine by extrapolation is 500,000,000 tones. Due to constraints in resources, the annual production capacity for the first five years of the project will be limited to 3.5 million tons.
4.5.3. Drilling and blasting design
The project will use controlled methods in order to ensure that the final pit slopes are steeper. This is by reducing the damages on the walls that results from blasting. Controlled blasting designs will incorporate blast holes of small diameters. They will be detonated as pre-shear lines in case the drilling encounters hard massive rocks. Alternatively, the blast holes will be detonated as post-shear or cushion lines in case heavily fractured or weak rocks are encountered during the drilling process. In either of these scenarios, the lengths of the blast holes will be staggered so that the bottom ends of the holes do not intercept rests of any benches below them (Hustrulid, 1999).
4.5.4. Loading/haulage requirements.
Loading requirements in this project will be matched by haul trucks that can be hauled using three to five cycles of front-end loaders or hydraulic shovels. In anticipation of dynamics in the climate, hardness and sharpness of rocks, the project will use tracked shovels. The project will also use rubber-tyred loaders for materials of low volume because of the low capital implications. Rail haulage will also be used to transport the material to the crushers that are off the site.
4.6. Project cost
Beside the capital implications involved in the project, below are some of the cost projections for annual recurrent expenditure:
4.7. Personnel
The salaried personnel requirements for this project include the project manager, a superintendent, a foreman, an engineer, a geologist, a supervisor, a technician, an accountant, a clerk, a secretary and security detail. The other personnel required for the project include people to carry out the various activities envisioned in the operations of the project.
4.8 Safety
Different safety issues will be considered in the project. The expectation is that these safety issues will emanate from high pressure water systems, proximity to power installations, ergonomic hazards emanation from handling of equipment, uncontrolled welding, exposure to dust and noise and proximity issues resulting from explosions. In anticipation for these safety concerns, the project will have a paramedic on site to handle cases that are not life threatening. Cases that require further attention will be referred to neighboring hospital using the ambulance that will be on site at all times.
References
Gokhale, B. (2011). Rotary Drilling and Blasting in Large Surface Mines. Boca Raton. CRC Press
Hustrulid, W. A. (1999). Blasting principles for open pit mining. Rotterdam: A. A. Balkema.
