Podzemni radovi

RANKING OF THE MOST IMPORTANT CRITERIA FOR THE SELECTION OF THE MINING METHOD FOR NON-STRATIFIED DEPOSITS

Dejan Bogdanović — 2024-06-28

Selecting and planning of the mining method for non-stratified deposits is the most delicate and complex process on which the success of the mine depends. This procedure is basically a multi-criteria decision making problem in which the aim is to select the best mining method from many alternatives. The aim of this paper is to show the influence of many factors (criteria) in the selecting of the most suitable mining method and to determine their influence on this process. The eight groups of influencing factors, i.e. criteria, were taken into account – geometric data on the ore body, the mechanical characteristics of the massif, the ore reserves, the situation on the surface of the terrain, the workforce, the possible environmental hazards, the market conditions and the safe working conditions. The AHP method was used for ranking these criteria. The ranking was carried out by mining experts and managers of various underground mines in Serbia using the group decision method. The results obtained show a clear distinction between the individual criteria when selecting the best mining method. Furthermore, the results clearly show the importance of the ranking process in determining the most influential criteria in this very complex process.

HYDROPHOBIZED LIMESTONE AS FILLER IN POLYMER MATERIALS

Slavica Mihajlović — 2024-06-28

The article shows changes in certain mechanical properties of polyvinyl chloride (PVC) depending on the quality of added limestone as a filler. Natural limestone and limestone hydrophobicized with stearic acid were added. Modification experiments were carried out with “wet” and “dry” processes in order to find out the required amount of stearic acid for a complete surface coating of limestone - degree of coating 99.90%. Coating of the limestone surface was achieved in the “wet” process with 1.5% stearic acid, while in the “dry” process the same degree of coating was achieved with 3% stearic acid. A significant amount of both “wet” and “dry” modified limestone was prepared.Such product was added to PVC mixture in order to investigate mechanical properties of the obtained PVC product. Research into the mechanical properties of PVC has shown that PVC containing limestone modified by the “wet” process exhibits better mechanical properties than that containing limestone modified by the “dry” process. For example, PVC obtained from a mixture containing limestone modified by the “wet” process with 1.5% stearic acid shows a better tensile strength of 54.20 MPa, while limestone modified by the “dry” process with 3% stearic acid shows a tensile strength 53.20 MPa.

DETERMINATION OF PARAMETERS FOR WET GRINDING OF PHOSPHATES IN A LABORATORY BALL MILL AND CLASSIFICATION IN A HYDROCYCLONE

Predrag Lazić — 2024-06-28

The company Elixir Prahovo uses dry grinding of raw phosphate in its production process. However, due to increased moisture in the raw phosphate causing difficulties in the dry grinding phase, the possibility of introducing wet grinding is being considered at the industrial plant in Prahovo. The moisture content of the incoming raw phosphate varies from barge to barge, ranging between 5-10% H₂O, which is very high for the dry grinding process and also create certain problems in the transportation system (the system of apron conveyors).

To assess the possibility of wet grinding of phosphates, predefined laboratory tests were conducted at the Department of Mineral Processing of the Faculty of Mining and Geology in Belgrade. This paper presents a portion of the results obtained during the aforementioned tests, which relate to the tested sample and its processing, as well as the determination of the particle size distribution of the initial sample, density, and bulk mass of phosphate ore. T In further investigations, grindability tests were conducted in a laboratory ball mill, and hydrocyclone tests were conducted on the ground phosphate in a laboratory hydrocyclone. Based on the results of these investigations, the necessary technological parameters have been determined to propose a scheme for the technological process of wet grinding and classification of phosphate. These parameters primarily relate to the material distribution in the hydrocyclone, pulp density in classification, and the particle size distribution of the ground phosphate.

UNDERGROUND LOADING-HAULAGE EQUIPMENT SELECTION WITH APPLICATION OF TOPSIS METHOD WITH DIFFERENT WEIGHTING METHODS OF CRITERIA

Vladimir Krivošić — 2024-06-28

The choice of adequate mining machines is one of the most complex problems in the underground exploitation of mineral raw materials. The weight of such a decision is reflected in the high prices of these machines and the occurrence of even greater costs during their use if their choice was wrongly conceived. There are numerous examples from practice in which such decisions were made solely on the basis of comparing the prices of machines, without considering any of the remaining important parameters that over time can bring significant benefits or harm to the investor. In this paper, by applying the TOPSIS method with different weighting methods of criteria the most suitable loader for work in the underground mine in question was selected. Based on 7 different criteria, a selection was made between 6 different loaders, which were produced by 3 different renowned manufacturers of mining equipment. The final benefit of this work, in addition to the selection of the most optimal loader, is that with some corrections, it can also be applied to the selection of other mining equipment in underground mines such as: trucks, boomers or bolters.

OPTIMIZATION AND ANALYSIS OF DRILLING AND BLASTING PARAMETERS USING O-PITBLAST SOFTWARE

Stefan Milanović — 2024-06-28

The development of modern technologies has enabled the application of specialized softwares in the field of mining through various segments and processes, including in works related to drilling and blasting. The application of specialized software for drilling and blasting with the use of modern technologies such as photogrammetry enabled more accurate data from the field for later processing. By processing data and creating a 3D model of the terrain for drilling and blasting works, it can obtain precise data, which serve us for the optimization of drilling and blasting parameters, as well as their analysis. The application of this type of specialized software, in this case, the O-Pitblast software, provides an overview of all parameters, as well as possible corrections and different scenarios regarding the results of the blasting itself. Optimization and analysis through this software can improve the results of blasting in terms of fragmented material size, and reduce the unwanted effects of blasting, such as the flyrock or blast vibration. The software has different types of tools that allow a detailed review and insight into the entire process from the beginning of planning drilling and blasting works to the very end and also printing of reports after the work is done.

DEFINITION OF CRITERIA AND ALTERNATIVES FOR CHOOSING THE OPTIMAL MINING METHOD DEPOSITS WHEN APPLYING MULTI – CRITERIA OPTIMIZATION

Sanja Bajić — 2024-06-28

When solving real problems, and to make a quality decision, it is necessary to consider a great number of often complex parameters. For these reasons, the development of decision-making process modeling has seen significant growth in recent years, and multi-criteria optimization models have stood out among them as useful for solving complex and conflicting phenomena. Multi-criteria optimization models make it easier for decision-makers to find the optimal solution in situations where there are many different criteria, which can often conflict with each other. The choice of the appropriate method of exploitation of mineral deposits follows the consideration of the problem and the approach to further development, which is primarily the determination of the criteria that influence the choice of the optimal alternative.