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    e-ISSN 2719-3306



Tamer RIZAOĞLU, Muhammed Ziya KARATAŞ, Canberk ÇOŞKUN
Kahramanmaraş Sütçü İmam University, Department of Geological Engineering, Turkey

The effect of the main component ratios in the joint filling
on the product quality

p. 180-190

When building materials are exposed to environmental and natural factors such as temperature differences, humidity, strong wind and earthquake in the areas where they are applied, irreversible damages such as separation, cracking and level difference occur in structures and building materials. In order to prevent these damages, the joints are left between the building materials and the gaps are filled with filling materials. The composition of the materials filling the joint gaps is also very important. The most important problems encountered in joint fillings are rupture, cracking and therefore permeability. In this study, it is aimed to compare the joint filling materials produced from different proportions of aggregate and white cement against rupture and cracking, and to determine the mixture ratio that exhibits the best performance. Five different recipes were prepared by using calcite powder as aggregate, white Portland cement as binder and water-repellent, volumizing and thickening chemical additives as auxiliary materials. On the prepared test samples; Capillary water absorption, water absorption by weight and volume, unit volume weight, saturated unit volume weight, porosity, compressive strength, bending strength, surface hardness and abrasion resistance tests were carried out. Considering the cost and environmental damage of cement, which is one of the main components in joint filler material, DD2 [Calcite (71.50%)] + White Cement (26.50%) + [Polymer + Cellulose + Plasticizer + Silicone] 2% has been detected as the most appropriate recipe.

Keywords: cement, joint filling, calcite, building materials


Muhammad Faisal SEPRIZAL, Machmud HASJIM, Restu JUNIAH
Mining Engineering Department, Faculty of Engineering, University of Sriwijaya, Indonesia

Technical analysis of fixed screen
in coal extraction activities (case study: PT. MAL)

p. 191-205

The extraction of coal is one of the activities involved in mining operations, where drilling, blasting, milling, crushing, sizing, and screening of minerals are performed. At PT. MAL, Indonesia, this extraction activity involves in-pit processing, such as the sizing of coal using a fixed screen. This study aims to analyze the technical sectors regarding the use of fixed screens in coal production activities. This is carried out to reduce the production time and costs, as productivity is expected to increase and completely meet market demands. The challenges involved in the use of fixed screens influenced the availability value of coal. In this case, the use of availability (UA) and effective utilization (EU) values of the utilized excavator were insufficient. These conditions were due to the observation of many challenges in the coal extraction activities. The challenges also affected the performance and production of the excavator, where the solution emphasized the redesign of the fixed screen through the modification of several parameters, such as the angle of repose and screen capacity.

Keywords:extraction of coal, fixed screen, modification, sizing


Volodymyr ANTONCHIK,
Institute of Geotechnical Mechanics of National Academy of Sciences of Ukraine, Ukraine
Kostiantyn ZABOLOTNYI, Valentyn HANKEVICH,
Dnipro University of Technology, 19 Yavornytskoho Ave., Ukraine
Vira MALTSEVA, Oleksandra KUTS,
Institute of Geotechnical Mechanics of National Academy of Sciences of Ukraine, Ukraine
Energy Economy Research Institute of the Polish Academy of Sciences, Poland

Constructional changes of pneumopercussion machines
for improving their efficiency

p. 206-215

Pneumopercussion machines (pneumatic impact machines) are widely used in all areas of human activity. Also, they are widely used in the mining industry. Unfortunately, their operation is characterized by a low efficiency of compressed air energy usage. In some cases, this level of efficiency is calculated as 15-20%. Such a situation increases the cost of drilling operations significantly. In this article, due to an implementation of a new construction of the equipment, the efficiency of the pneumopercussion machines was increased. This problem is solved by combining the most effective thermodynamic processes of compressed air in the working chambers of machines. Also, a new technical solution for the construction of pneumopercussion machines is suggested by the Authors. The proposed new design is realized by a combination of the most effective thermodynamic processes in the chambers of pneumatic impact machines. A new pneumatic hammer is presented, which allows to reduce compressed air consumption twice during an operation on the surface (in comparison with hammers available on the market). The operation of pneumopercussion machines and the method of calculating geometric parameters are described. The economic performance of the equipment confirms the correctness of the proposed technological solutions.

Keywords: pneumopercussion machines, thermodynamic processes, hammer, compressed air


Artur Konewecki
Elektrometal S.A., Poland
AGH University of Science and Technology, Poland
Krzysztof Rozwadowski, Rafał Pasek,
Wieliczka Salt Mine S.A., Poland
Szymon Molski
AGH University of Science and Technology, Poland

Stress measurements at load-bearing components
of theshaftsteelwork and the mine hoist frame
in the Regis Shaftofthe Wieliczka Salt Mine

p. 216-228

The study summarises the selection of dedicated techniques and procedures for measuring real stresses arising in shaft steelwork components due to car-shaft steelwork interactions as well as stresses at critical points of the car frame in the elevator installation in the Regis Shaft of the Wieliczka Salt Mine. The implemented solution and operational parameters of the hoisting installation in the Regis Shaft of the Wieliczka Salt Mine are summarised, the adopted measurement method and dedicated equipment are presented, focusing on the procedure for locating the critical points on the car frame and shaft steelwork. The purpose-built measurement set-up as well as the adopted stress measurement procedure and results are explained in detail.

Keywords: measurements, hoisting installation, mine elevator, stress, shaft steelwork, elevator car frame


Grzegorz OLSZYNA, Andrzej TYTKO
AGH University of Science and Technolology, Poland

A tool for determining the number of bends and places
of accumulation of potential wear of steel ropes operating
in the luffing systems of basic opencast mining machines

p. 229-237

This article presents the issues of the wear of steel ropes operating in the lowering systems of the largest wheel excavators (BWE), type SchRs, Rs, KWK operating in KWB Bełchatów. Sudden degradation of these ropes may lead to the complete shutdown of the BWE-Belt-Stacker system from operation. However, this can be avoided by regular visual inspections of hoist ropes. Unfortunately, the rope systems in each excavator are different, and their availability is difficult. In order to simplify this task, the authors of this paper have developed an IT tool that allows the modelling of a given multi-pulley rope system and the indication of critical places on the rope for given working conditions. A simplified description of this tool is the subject of the article.

Keywords: bopencast mining, steel ropes, rope modelling, rope wear


Teodor-Costinel POPESCU, Alexandru-Polifron CHIRIȚĂ,
Ana-Maria Carla POPESCU, Alina-Iolanda POPESCU

National Institute of Research & Development for Optoelectronics /
INOE 2000-subsidiary Hydraulics and Pneumatics Research Institute –IHP, Romania

Use of pumping units equipped with oscillating hydraulic
pressure intensifiers for displacement of cylinders
with heavy loads over the entire stroke  

p. 238-248

Working and moving in confined, limited and narrow spaces, specific to underground mining activities, also requires the use of hydraulically operated equipment, capable of developing large forces, with small dimensions. An example of such equipment includes pumping units comprising low-pressure electric pumps and oscillating hydraulic pressure intensifiers. They use low pressure in the primary side of the intensifier and generate high pressure in the secondary side of the intensifier. Such pumping units are usually used to achieve and maintain high pressure, either in the volumes of closed spaces (in  strength tests on pipes and tanks) or at the end of the active stroke of hydraulic cylinders (in hydraulic presses). On an experimental laboratory bench, which comprises a test cylinder, powered by a pumping unit, equipped with an oscillating hydraulic pressure intensifier, and a load cylinder, powered by another pumping unit, with the possibility of load control, the authors show that: the application range of these pumping units can be extended in the third direction, too, useful for underground mining activities, namely for drive of hydraulic cylinders with low gauge / displacement speeds and constant high load (high working pressure) over the entire working stroke length; the uniformity of displacement of these cylinders, with load throughout the stroke length, which are powered and driven with such pumping units, is slightly affected by the pulsating mode of operation of the hydraulic pressure intensifier. A set of experimental measurement results is presented for a constant value of the load over the entire displacement stroke of the test cylinder.

Keywords: low-pressure pumping unit, oscillating hydraulic pressure intensifier, high pressure, hydraulic cylinder


Silesian University of Technology, Poland

Influence of nonlinearities in sensor and actuator on the operationof the rotational speed control system of a roadheader cutting head 

p. 249-257

The paper presents a discussion on the selected nonlinearities existing in sensor and actuator subsystems of the roadheader cutting head speed control system. There have been concerned the most significant nonlinearities - rotational speed encoder and frequency rate limiter in the input of the power electronic converter. There has been presented a detailed analysis of the nonlinear input frequency rate limiter and the frequency-dependent input-output curves have been calculated. They enable qualitative and quantitative evaluation of system performance over a wide range of input signal frequencies and amplitudes. The measurement time of the encoder-based speed sensing should be as short as possible, or continuous measurement (like tachogenerator) should be used. The impact of encoder delay and inertia is much less significant than that of the frequency rate limiter. For better drive system performance, the frequency converter should be overmatched to ensure current overload capability – allowing an increase in the permissible rate of output voltage frequency change.

Keywords: roadheader, speed control system, rotational encoder, power electronic converter, rate limiter, describing function.