Ecological Costs of Open Pit Coal Mining and Their Influence on Ultimate
Pit Design
Xiaowei Gu, Qing Wang*, Xiaochuan Xu, Yu Lei
Northeastern University, Shenyang, Liaoning, 110819 P.R. China
Mining operations, especially surface coal mines, have great impacts on the local ecosystem
and the environment. However, it has been a common practice in mine design that the
economic evaluation considers only the tangible costs in the corporate accounting system,
while the costs incurred due to ecological/environmental damage are left out. Such practice
underestimates the total cost of mining and ignores the difference in ecological/environmental
impacts between different mine design alternatives. With growing interest in sustainable
development, the mining industry is under increasing pressure to operate not only based on
economic and engineering principles but also on principles of sustainability. Therefore,
estimating ecological costs of mining and considering such costs in the mine design process is
an important step towards reducing ecological/environmental impacts at the design stage.
The objective of this paper is to quantify the ecological costs of mining and to demonstrate
the influence of such costs on the ultimate pit design for open pit coal mines. The ecological
costs of mining are estimated based on the areas and types of land damaged by mining
activities and the carbon emission from energy consumption. Four categories of ecological
costs of mining are identified: 1) prevention and restoration cost, 2) the lost value of
bio-product production, 3) the lost value of indirect eco-services of the damaged ecosystem,
such eco-services mainly include soil erosion control, water runoff control, oxygen release,
carbon absorption, and soil nutrients formation, and 4) the cost of carbon emission from
energy consumption of mining. The estimation of these costs is discussed and necessary
equations are given for their calculation.
A case study is carried out on a large multi-seam open pit coal mine located in Northeast
China. Based on the coal deposit model, an ultimate pit is first optimized without considering
ecological costs using a cone eliminating algorithm. The damaged land area and the energy
consumption are then calculated for this pit and the ecological costs are estimated. The total
ecological cost is attributed to the unit cost of overburden removal and coal mining and the
ultimate pit is optimized again. Since the damaged land area is not a linear function of the pit
volume, the ecological costs must be recalculated for the new pit and the pit is optimized yet
again using the ecological costs of the new pit. This iteration process terminates when the
ecological cost per ton converges and the resulting pit is the optimum pit when ecological
coats are considered. The optimum ultimate pits with and without ecological costs are
compared to show the influence of ecological costs on the pit design outcome.
Key words: Ecological cost, open pit, coal mine, design
* Corresponding author: qingwangedu@163.com