Selective mining of multiple-layer lignite deposits. A fuzzy approach

In this paper the development and the application of a fuzzy expert system for the evaluation of the exploitable reserves of multiple-layer lignite deposits, mined by continuous surface methods, is presented. The exploitable reserves are determined decisively by the structure of these deposits, as well as by the limitations of the used mining systems. In practice, thin layers of lignite and interbedded waste layers are grouped under specified assumptions regarding thickness and ash content, to form the exploitable blocks. Moreover, the decision for excavating such a block is made under subjective constraints of different importance, or by using uncertain data. Advances in fuzzy inference systems (FIS) have provided a new approach to the evaluation of multiple-layer lignite deposits. FIS have the ability to handle imprecise, incomplete or linguistically ambiguous information and incorporate them into decision-making processes. In the developed FIS (Mamdani type) new linguistic variables, related to working conditions, operators’ experience and production were involved. The FIS was used for the estimation of the exploitable reserves of the Southern Field lignite deposit, located in the area of Ptolemais (Greece).