S. Maksimovic’s research while affiliated with Institute of Physics Belgrade and other places

Intersector models are efficient mathematical and modeling tools, which are well studied and widely used in economy. It is contradictory that intersector analysis is neglected in mining, especially since no other field has accepted and implemented the application of the model of operation research as mining did. There are not many satisfactory explanations as to why this is so. In order to explain this dilemma, this paper is directed at the peculiarities and characteristics of the intersector analysis, towards observation of its application in the mining industry on the intersector model of the Mining basin of Kolubara, which operates in the system of the Electric Power Industry of Serbia, and demonstrates the implementation and validation of observations and conclusions.

The paper presents two model approaches to life cycle assessment of auxiliary mining machines: one of them is based on reliability theory and the other on the principle of cost-effectiveness. During exploitation of machines, the level of their reliability decreases while operating costs increase. These indicators of opposing trends detect the operating capacity of machines and provide the basis for making a decision on the validity of further operation, maintenance, or replacement of machines. By considering an example of a dozer, as the most frequently used machine for the performance of auxiliary works in the surface coal mines of Electric Power Industry of Serbia, a comparative analysis was made for applying both model approaches including assessment and conclusion.

The paper is focused on the problem of determining the optimal exploitation life of the long-lasting mining machinery, such as bucket-wheel excavators, excavators with one working element of large capacity, spreaders, self-propelled transporters, conveyor belts and similar machinery. A concept of approach is presented, and an application of the dynamic model with the undefined interval is given by using the example of the bucket-wheel excavator. The paper concludes with observations and assessments regarding the subject matter. Key wordsBucket-wheel excavators-machinery exploitation life-optimization-operations research-replacement theory-dynamic programming

The problem of determining the optimum exploitation life of machinery, namely, the optimum time for machinery and equipment replacement, represents a complex and highly responsible engineering task. Taking into consideration the situation prevailing at coal pit mines in Serbia, the tasks of this rank are very complex and difficult. To make a decision on the replacement of capital equipment and machinery, such as bucket wheel excavators within the mentioned systems, implies a management task of utmost responsibility. It requires high professional and analytical knowledge as well as reliable arguments, based on a multidisciplinary professional approach. We present their views on the problem of establishing the optimum exploitation life of bucket wheel excavators, offering an algorithm, based on dynamic programming, as a solution.