Material Transport System DesignFest Problem Majid Nabavi, Shasha Wu, and Mohamed Fayad [email protected] and {shwu, fayad}@cse.unl.edu Material transport system introduces different methods for transporting solid and liquid materials. A solution to this problem should encounter a system that is using one or multiple methods for transporting materials to their destination. Materials Transport by Trucks The first method is transporting raw materials by trucks, specifically in a mining operation. In a mining open pit, mechanical shovels load materials from depots into dump trucks, and trucks transport material to destinations. They transport ore to mineral processing facility to be processed and prepared for the market, and transport waste rocks to waste dumps, to prepare the existing ore under them for extraction. This method requires a number of mechanical shovels, a fleet of trucks, and a scheduling system to dispatch trucks in an efficient way, minimizing their waiting times and making sure the system will achieve the transport goals within the designated time. Figure 1 illustrates a typical open pit with five active loading points and the routes Figure 1: Material transport in open pit mining Waste DumpP11W68W2Mineral Processing Facility10972PW354321NFigure 2: A vertical profile of open pit and the ore body situation. Material Transport with Conveyor Belt An alternative method of transporting materials is using a conveyor belt system. The conveyor belt system is basically consisted of a reinforced, endless elastic belt with a constant width and thickness, moving over a series of rollers, and rollers are installed on chassis. Attributes of this system are length, width, speed and the engine power. These attributes along with the gravity and angle of repose of the bulk material determine the capacity of the system for transporting materials. The size of materials matters in this system, large size of rocks may damage the conveyor belt and fine sizes may be slipover, an optimum range is desirable. MaterialConveyor BeltRollerAngle of ReposeChassis Figure 3: Cross section of a conveyor belt This method can be used in combination with trucks or as a substitute method. This method is applicable to mining and materials transport operations that handle a high volume of materials in a steady rate for a long time. In this method, loaders carry materials from the depot and dump it into feeders, in a short distance of the extraction site. Feeder feeds a crusher in a steady rate and crusher reduce the size of rocks to a proper size for transporting by conveyor belt. The whole system must be consistent in terms of capacity of materials flow. Loaders must carry the required volume of material in a time say, ton/hour, feeder must feed the crusher by the same rate and crusher must be able to deliver the same amount of material with the proper size to conveyor belt. OreWasteSConveyor belts in turn must have the proper width and speed to transport the material. If any of the elements of this system fails to keep up with the required rate of materials flow, there will be a material congestion at that point and the whole system will fail to achieve its goal of transporting the designed quota of material to the destination. Material depotLoaderFeederCrusherConveyor beltFigure 4: Transport materials by conveyor belt Under this situation, the shovel-truck model can’t satisfy the new requirements. We must modify the model. Transport solid materials through pipeline Transporting solid materials through a pipeline is the efficient and most economical method depending on the type and volume of materials, topography of the aria, and the distance. This method is used for relatively long distances, where huge quantities of material are transported during a long period of time. As you see in Figure 3, in this method material is loaded from depot of extracted materials into feeder by loaders. Feeder passes the material into crushers in a steady rate and materials go to ball mill after passing through the crusher. Ball mills reduce the size of materials to micron range and prepare them for transportation through pipelines. The milled materials are poured into mixers, where water is added to them, to make slime and then pump it to the pipeline. The pipeline then conducts the material to the destination. The process is showed as figure 3. LoderFeederCrusherBallmillConveyorMixerPumpPipelineFigure 5: Transport materials through pipelineTransport liquid materials We can consider the pipeline transport as a general method of transporting liquids like oil and water. These materials are also typically transported in a high rate, to a remote destination, for a long period of time. As we can see in figure 4, crude oil is extracted from the oil well, and depending on the nature of the oil reserve some pressure control process is necessary to get the flow under control and separate gas and volatile liquids from the oil. The pressure control and separating gas is a complicated operation, we consider it just as one of the components in our system. After controlling the extracted oil, it has to be transported to refineries or reserve tanks in ports, all considered as destinations. Pumping system pumps oil into the pipeline, depending in the pipeline length several pumping stations may work along a pipeline to keep the pressure high enough to run the flow with desired speed. PipelineOil WellPressure Control InstallationsPumpTank Figure.6- Oil transport system Use Cases: UC1.1. All dump trucks are going to start their work shift. They have to be assigned to different origins of loading to load ore or waste and transport them to destinations. Actors: Dump truck, Schedule, Shovel, Ore, Waste. Roles: Dump truck: Transports ore to mineral processing facility or waste rocks to the waste dump Schedule: Checks the status of shovels and Assigns dump trucks to the right shovel Ore: A pre determined amount of that is transported to mineral processing facility Waste: A pre determined amount of that is transported to the waste dump After arriving to the loading point, every truck spends one minute for maneuver and positioning before shovels start loading. The next truck(s) arriving to the same point will line up for loading that takes three minutes for each of them. Schedules have to send dump trucks in a way that the total time they spend in lines is minimized. UC1.2. A dump