Demonstrating Efficiency Gains from Installing Truck Turntables at Crushers. M Brazil, P A Grossman, J H Rubinstein and D A Thomas

Transcription

1 Demonstrating Efficiency Gains from Installing Truck Turntables at Crushers M Brazil, P A Grossman, J H Rubinstein and D A Thomas

2 The players The mine design research team at The University of Melbourne: More than 15 years experience in developing underground mine design software. Particular expertise in optimal design of decline and level access networks. The Australian Turntable Company (ATC): Manufactures and installs turntables for a variety of purposes. Recently started manufacturing turntables for ore trucks. Our task: To develop software for ATC for quantifying the benefits of installing turntables at crushers on mine sites.

3 Ore trucks at crushers Crusher To Mine Area 1 To Mine Area 2 Aerial view of crusher site at a mine. Tipping is performed from the front and the rear of the crusher. There are two mining areas. Trucks return to the same area, giving four haulage paths. Trucks stop, turn and reverse up to the crusher. Significant costs: Time Fuel Tyre wear Other considerations: Safety Rock spillage Level area required

4 Truck turntables can be installed at the dump points. The turntable rotates before tipping but not after. The truck can enter the turntable from any direction in a 180-degree range. The truck leaves by driving directly away from the crusher. Truck turntables at crushers

5 ATC s requirements ATC was carrying out the following calculations manually: Generating truck haulage paths in the vicinity of crushers, with and without turntables installed. Comparing the scenarios with and without turntables with respect to time, fuel consumption and tyre wear. ATC required a software tool that would perform these calculations automatically. Benefits of a software tool: ATC staff could do the calculations more efficiently. By using optimising algorithms, near-optimal paths could be generated. ATC could use the tool to demonstrate the benefits of turntables to clients. The tool could be further developed into a strategic design tool for use by mine planners.

6 Optimal curvature constrained paths Truck paths are constrained by the radius of the truck turning circle. The paths should be as short as possible subject to this constraint. We used the mathematical theory of shortest curvature constrained paths in the plane: Paths without reversals (Dubins, 1957); Paths with reversals (Reeds & Shepp, 1990). The research team has previously used this theory to generate near-optimal designs for decline networks in underground mines.

7 Optimal forms for curvature constrained paths No reversals One reversal Optimal paths consist of arcs with the minimum turning radius and line segments. The shortest path between two directed points with no reversals or one reversal takes one of a limited number of forms. For the present application we used the forms shown and their mirror images.

8 The Truck Path Optimisation Tool We developed the Truck Path Optimisation Tool (TPOT): Stand-alone program that runs under Windows. Written in C++ and developed in Microsoft Visual Studio. Interactive tool that rapidly calculates, evaluates and compares truck paths with and without turntables. ATC are now using the tool in their work.

9 Truck Path Optimisation Tool inputs and outputs Required inputs with source indicated Scaled image of dump area mining company or Google Earth Truck kinematic parameters mining company and truck specs Turning circle radius truck specs Fuel consumption rates truck specs Tyre wear rates tyre specs Turntable kinematic parameters ATC Outputs Optimal truck paths with turntables without turntables Truck times, fuel consumption and tyre wear with turntables without turntables Savings in time, fuel consumption and tyre wear obtained by installing turntables

10 The Truck Path Optimisation Tool in use Image loaded and scale set.

11 The Truck Path Optimisation Tool in use Parameter values entered.

12 The Truck Path Optimisation Tool in use Truck entry and exit points set.

13 The Truck Path Optimisation Tool in use Dump point set. The path with a turntable is calculated. Generated paths sometimes pass through no-go regions. The tool allows the user to add waypoints. Waypoints can be used: To guide the route taken by a path. To reproduce the paths in current use without turntables.

14 The Truck Path Optimisation Tool in use Waypoint added.

15 The Truck Path Optimisation Tool in use Path without a turntable. A waypoint has been added here also.

16 Paths with two mine areas and front & rear dump points With turntables Without turntables

17 Example of savings obtained In this example, the following savings per trip were obtained: seconds of truck time litres of fuel mm of tyre wear For this mine, these results equate to the following savings per year: 1666 hours of truck time (potentially allowing a truck to be removed from the fleet) 480,000 litres of fuel 57 mm of tyre wear (>75% of total permitted wear on a tyre)

18 Planned enhancements The following enhancements to the tool are planned. Trucks can be delayed in the crusher area if they have to give way to each other. By modelling the traffic flow, the tool will be enhanced to: Eliminate path crossings where possible. Optimise path configurations at crossings. Optimise the truck schedules. Other enhancements: Calculation of dollar costs for time, fuel and tyre wear. Facility for the user to place barriers on the image to define no-go regions.

19 The enthusiastic support of Paul Chapman and the staff at ATC is gratefully acknowledged. This project was financially supported by the Victorian Government Technology Voucher Program.