A Study on the Preliminary Cost Estimation for Hydraulic Backfill Process in Barapukuria Coal Mine, Dinajpur, Bangladesh

Abstract

In this study, a preliminary cost investigation is conducted to evaluate the economic feasibility of hydraulic backfill process for the Barapukuria coal mine located in the north western part of Bangladesh. Recently by Longwall Top Coal Caving (LTCC) without stowing or backfill method, the mine is extracting Permian age bitu minous fair quality coal which belongs to Gondowana Fo rmation rests on Precambrian Basement. In fact, where different geological structure s and hydrogeological conditions are the prime obstacles for low recovery along with v isible environ mental impacts like subsidence around the mine area. The Cost analysis demonstrates the economic feasibility of backfill system, a prospective option for mine status devel- opment. In this research, the cost of backfilling incur in unit volu me through the evaluation of required backfill materials price where the total capital cost of the plant is assumed and maintenance cost exclude fro m the calculation. Prior to the calculation, a detail discussion on the available backfill materials is done which gives an overview of the cost scenario of the materials. As the current market value, the result y ields the cost of sand is $0.45 per m3; cement is $187 per cubic met er and ash is $.17 per m3. For the ash, the transportation cost is only considered. The cost for d ifferent mixture of backfill per cubic meter is also deter mined that reveals the availability of the backfill materials and ease of transportation reduces the backfilling cost in the mine. However, the cost is mostly influenced by the cement price. Total material cost for 84%sand, 6% cement and 10% ash mixture is evaluate d as $708.48 M fo r full ext raction and $70.85 million for 10% recovery. In addition, accord ing to current production rate require fill materials cost is $6.20 million per year. In economic evaluation with general project cash flo w chart, this study shows that the returns in three categories such as directly ore ext raction increment, indirectly s ubsidence and reduction of environment pollu- tion. Finally based on the recent revenue criterion and overall cost consideration favors the backfill process in Barapukuria coal mine. For mo re detail, fu rther study on detail cost investigation including defin ite capital cost and operational cost is recom- mended to complete evaluation of economic feasibility in the mine.