Decision-making models in mining:the case example of the Golgohar 6 iron ore deposit, Iran

Abstract

This research is divided into two general sections. First, the significance and purpose of the study are examined according to conditions of iron ore production and consumption. This part is focused on iron ore resources, extraction and consumption in Iran and the world. Then, comparison of demand and supply of iron ore and reasons why iron ore production will increase are explained, such as population and urbanisation growth, industrial development, new extraction technology, and specially in Iran the availability of inexpensive energy and establishment of new steel plants. Iron ore exploration results in Iran identify new iron ore deposits, such as Golgohar 6, D19 and A13, which have a high amount of overburden. Open pit mining for these deposits is not evident and needs careful evaluation. The selection of the mining method is very important for mine design, particularly for low-grade and deep deposits. The major factors in the selection of the mining method are the geometry of the ore body, extraction rate, economic and technical factors. A critical assessment of these factors would be helpful for the decision process. Therefore, the second part of this research provides a systematic evaluation of mining methods in iron ore deposits, with particular focus on the application of fuzzy set theory. Three procedures for the selection of a mining method are applied:  Qualitative method  Numerical ranking method  Decision-making model This work is mainly focused on a decision-making model based on fuzzy set theory. While the qualitative method mainly defines possible extraction methods, the numeric ranking method and the decision-making model compare alternative mining methods. This approach is applied to the Golgohar iron ore district which is one of four iron ore regions in Iran. In the Golgohar area, six iron ore deposits are recognized by airborne surveying, and Golgohar 6 is one of the deepest deposits. The resource of Golgohar 6 amounts to 65 million tonnes with a grade of 56% Fe. The thickness of the orebody is about 100 m and the depth is between 500 to 600 m below surface. Exploration activities for Golgohar 6 include geological investigation, geophysical measurements (airborne surveying, magnetometry and gravimetry), core drilling, sampling and analysis. The application of the above selection procedures for the Golgohar 6 deposit defines that both the surface mining and the sublevel stoping method are appropriate extraction methods. The preliminary economic study of surface mining with shovel and truck versus surface mining with semi-mobile crusher and conveyor as well as sublevel stoping constrains the most suitable mining method for the current information level of the Golgohar 6 exploration project. However, the density of the current exploration data (indicated mineral resources) is not sufficient for making a final decision on the mining method. The continuation of exploration activities and more exploration drilling (the spacing between the drill holes should be 50 m or less) are…