Master of Philosophy
School of Civil, Mining and Environmental Engineering
Underground coal mine logistical operations involve activities such as transportation of coal from the longwall faces and roadway development units to the mine surface, transportation of consumable materials, operational crews, mining equipment and other supplies from the mine surface to numerous underground drop points to support the four key operations of the mine: longwall production, roadway development, gas drainage and mine construction. Underground coal mining logistics can be clustered into the three broad groups of activities: transportation/delivery of coal from longwall extraction face, through the belt conveyor system, to the mine surface; transportation of materials and other supplies (e.g. consumables) from the mine surface to the underground buffer areas and then to the final consumption points using multiple means of transport (underground development headings being mostly, for the purpose of roof support and ancillary advance); and transportation of personnel to different working sites underground, mainly using shafts and drifts.
This thesis studied underground coal mining logistics using a modern simulation program by integrating the underground mining operations into one simulation model and focusing on the roadway development unit only. The model has been validated with historical performance data and input parameters collected from mine sites. By considering the randomness and real interactions between every operation, the simulation results demonstrated that it’s a very viable method of analysing system constraints and optimizing the performance of underground coal mining logistics systems. It allows engineers, mine operators and researchers to optimize the selection of equipment and other resources through the way of evaluating alternative “what if” scenarios via the model, rather than relying on costly field trials. The case studies fully examined the logistics of both coal transportation from the continuous miner to the conveyor belt and the material supply from the pit bottom to the development headings.
The roadway development rate is affected by multiple factors. The simulation and analysis of coal transportation together with support operations showed a potential of 30% performance increase with current support technology and faster coal transportation. The historical support operation was about 17 minutes per metre. If the support operation can be improved to be within 12 minutes per metre which is observed from practice, the overall performance would be improved by 20%, from about 20m a day to 24m a day. If the 12 minutes per metre support operation could be achieved, the performance can be further improved by another 10%, from about 24m a day to more than 26m a day by utilizing a faster Shuttle Car for the coal transport to the boot end.
As for the supply of material to the development face, the rate of material supply has a minor effect on the roadway development rate. With regard to the duration and frequency of the material supply operation and the distance from the material storage to the surface, the duration of material supply has a linear relationship with the roadway development rate across all reasonable supply intervals. However, with four times the duration change, the development rate only changes from about 3.33% at the least frequent supply to about 8.33% at the most frequent supply, which means the material supply duration only has a minor influence on the roadway development rate. Further simulation studies demonstrated the material storage distance has basically a linear relationship with the roadway development rate. However, the effect is minor, where the change is only 0.7m per day (1%) with about a 500-metre difference overall with respect to the total distance. For every 100m decrease between the material storage and the development heading, there is an improvement of about 0.2% in the development rate.
Further, the simulation results and analysis support the opinion that the random long-time delay of logistical supply causes a major logistical issue which may come from the communication and scheduling of the material supply from outside the mine to the panel material storage area or the breakdown of machines. An average of two hours delay for every 40m advancement can cut down the total development rate by 15%, while a 22% development rate drop would be caused by an average of two hours delay at the frequency of about every 12 hours on average. The effect of both type of delays caused about a 39% drop in the development rate. With a one-hour incremental delay applied to both types of delay simulated, there is a 51% decrease of the development rate. Respectively, an average of three hours delay for every 40m of advancement can cut down the total development rate by 20%, while a decrease of 33% in the development rate would come about by an average of three hours delay at the frequency of about every 12 hours on average.
Cai, Liyong, Using FlexSim to Simulate the Logistics Relationship between Materials Supplying and Roadway Development, Master of Philosophy thesis, School of Civil, Mining and Environmental Engineering, University of Wollongong, 2017. https://ro.uow.edu.au/theses1/362