Tomasz Wydro

Underground mining operations require the preparation of access, development, and production workings to enable the extraction of mineral resources. These excavations serve several functions, among which the transportation of personnel, machinery, materials, and mined rock is essential. Since transportation is frequently carried out along the mine floor, maintaining its proper condition is crucial for ensuring operational safety and efficiency. Existing floor maintenance methods, including manual operations, roadheaders, and crawler tractors equipped with bulldozer blades, are characterized by limited effectiveness, high operating costs, and considerable labor intensity. Moreover, the confined dimensions of underground workings prevent the use of conventional surface earthmoving equipment. The paper presents an innovative solution designed for mine roadway floor maintenance, based on a tracked tractor equipped with a cylindrical milling cutting head with conical picks reinforced with special protective coatings. The proposed cutting head features a modular three-segment design with interchangeable drums of different cutting widths, enabling simultaneous floor profiling and drainage channel construction while remaining compatible with the restricted geometry of underground mine workings. The operating performance of the cutting head was evaluated through numerical simulations for different values of the rock cuttability index (1500 and 3000 N/cm), cutting depth (100 ÷ 300 mm), and machine feed speed (2 ÷ 6 m/min). The operational parameter analysis, based on calculations and simulations, demonstrated that effective floor cutting would be achieved within acceptable values of cutting forces and power consumption. The proposed solution represents a new category of machinery dedicated exclusively to underground mine floor maintenance. The developed concept has the potential to improve transportation safety, reduce roadway maintenance costs, and increase the operational efficiency of underground mining systems.

The primary means of rail transport in inclined workings up to 45° are typically single- or double-drum rope winches. These winches are part of a transport system consisting of the winch itself, a rope with a diameter d and length Ll, a track system, and a return drum with a rope tensioning mechanism. A fundamental challenge in employing winches in a given working is accounting for their operational conditions, which include the route length Lu, its inclination αu, and the value of the hauled mass (weight) Gm, given a specified load transport velocity vpł. These factors influence the drive load parameters, such as the winding rope force FC, unwinding rope force FS, and drive motor power Np. Manufacturers of these devices provide their structural (Lumax), kinematic (vpj), and energy-related (Np) parameters. However, it is the responsibility of the prospective user to assess the suitability of a specific winch for the conditions present in their transport excavation. To address this need, an analytical model, algorithm, and computer program have been developed to dynamically determine the required parameters while considering the winch’s operating conditions.

Due to their simple design, high reliability, and low energy consumption, belt feeders are a fundamental means of transporting bulk materials, particularly in continuous feeding systems. The most commonly used belt feeders are short ones, with lengths up to 40 meters and belt widths up to 1 meter. In addition to their use in underground and open-pit mining, they are widely applied in energy, metallurgy, and other industrial sectors and in transshipment ports, storage yards, and stockpiles. The proper operation of belt feeders is ensured by maintaining their structure’s required stability and rigidity under specific operational conditions (installation location). It applies to feeders operating on straight stationary supports, particularly on V-type stationary and mobile supports. Various computer programs are used during the design phase of these feeders to assist and facilitate the process because, despite standard components and assemblies, belt feeders are not repeatable solutions and require multi-variant calculations. Based on a typical belt feeder, its analytical model, and dedicated software, the stability and forces acting on the supports are investigated. This software enables and facilitates the analysis of the stability and support loads of a belt feeder during its design phase or when implementing structural modifications. It may be particularly useful for current and future users introducing changes to the feeder’s structure or relocating it to a different operational site. The presented application was employed in the analysis of a belt feeder at an open-pit mine during the process of modifying its drive unit.

A central engineering concern in the use of such winches is their energy intensity, which is significantly influenced by operational factors such as the length and gradient of the transport route, the transported weight, and the target hauling velocity. These variables directly affect the drive system’s load and thus the power demand of the motor, which represents the primary component of the system’s energy consumption. While manufacturers typically provide structural, kinematic, and power-related specifications, the user must evaluate whether a given winch can operate efficiently within the energy constraints imposed by specific site conditions. To aid in this assessment, an analytical model, along with a computational software tool, has been developed. This solution enables the continuous determination of essential parameters, with particular attention paid to the energy requirements of the system, supporting informed selection and implementation of winches with appropriately rated motors to optimize energy consumption. For the analyzed case, it was calculated that doubling the transport distance results in an increase in energy consumption of approximately 50%. Moreover, an increase in the velocity of the transported weight by only 0.5 m/s leads to a rise in energy consumption of approximately 25%.

Belt conveyors, owing to their simple construction, high reliability and relatively low energy consumption, are the basic means of transporting loose and granular materials. Currently, thanks to continuous development, belt conveyors can reach a length of up to several kilometres, and their belt width can be more than two meters. Such possibilities are achieved thanks to increasingly better belts and drives. However, the most common are short belt conveyors with a length of up to 40 m and belt widths of up to 1 m, frequently referred to as belt feeders. Apart from the mining industry, they are widely used in power engineering, metallurgy and other industries (chemical plants, trans-shipment ports, storage yards, etc.). The design of machines, including belt feeders, is based on calculations. Modern design in technology is based on advanced computational methods and the possibilities of computer technology. Multi-variant simulation calculations are necessary, especially in the case of belt feeders, where none of the devices—despite the use of typical elements and subassemblies—are a repeatable solution. Only this procedure guarantees the selection of rational solutions already at the early stages of design. Therefore, in this article, an analytical model of a typical belt feeder was developed and its stability and forces in the supports were determined. This allowed the development of an application for testing the stability of the belt feeder at the design stage or when introducing structural changes.

The cutting tools in mining industry are especially prone to rapid wear, since most of the rocks exhibit aggressive abrasion attributes. A typical representative of fast wearing mining end-tools is a conical pick (also known as tangential-rotary cutter). In order to decrease the premature deterioration, the manufacturers and users tend to enhance the lifespan of the tool by wide range of approaches, namely heat treatment, chemical treatment, burnishing, hardfacing etc. In order to estimate the wear rate of a given pick one has to select appropriate procedure and method of evaluation. By this time, most commonly applied method is to estimate the wear rate basing on mass loss measurements of the tools being exploited with constant cutting parameters and fixed conditions. The Authors proposed also a new method of volumetric wear assessment, basing of three-dimensional photogrammetric scanning and compared the results with the outcome of traditional mass wear evaluation of the same sets of tools. Additionally, this paper contains recommendations regarding both approaches (volumetric and mass), especially focusing on the possibilities of the new method concerning measurements of the manufactured tool.

The wearing of cutting tools is a bottleneck of many branches in the industry. However, the tools used in the mining sector are extraordinarily prone to rapid deterioration since many rocks exhibit aggressive abrasive properties. A typical example of a fast wearing cutting tool is a conical pick. It is used in the mining industry and other businesses requiring rock cutting, such as in roadworks and tunnelling. Both manufacturers and users attempt to find a way to enhance the lifespan of the working surface of conical picks via different approaches, namely heat treatment, chemical treatment, work hardening, and hardfacing, etc. To correctly estimate the resistance to abrasive wear for a particular conical pick, one must select appropriate procedures and methods. By this time, the most common estimation method is to measure the mass loss before and after cutting, preserving the specified and constant conditions. This method was developed for users (mines) and manufacturers of cutting tools, especially conical picks. Alternative methods of assessing the picks’ wear are also sought. In this paper, the authors perform additional volumetric loss measurements via a photogrammetric approach, which results in a 3D scan of brand-new and exploited conical pick. Three different sets of four picks were measured both in the domain of mass loss and volume loss, and the results were compared. Slight differences in parameters C2 and C3 were found. Additionally, the authors enclose recommendations regarding the proper use of the methods mentioned above, mainly focusing on the ability to perform linear and angular measurements of the tool performed on the 3D scan.

The cutting heads currently used in longwall shearers, roadheaders, road milling machines and excavators are equipped with cutting tools called picks. The most commonly applied are conical picks, less frequently—radial picks or tangent picks. The picks are detachably mounted in holders installed on the body of the cutting head, to which they are usually welded (shearers) or, less frequently, form-connected (road milling machines). The arrangement of picks and holders (positioning) on the body of the cutting head, according to a previously designed diagram (pick arrangement), enables extraction of the mineral with a specific width (web) and diameter (height). Ideally, the pick arrangement should generate the lowest cutting resistance, which loads the cutting machine. The pick arrangement is characterized by design parameters (number of holders, pitch in the line and between the cutting lines) and kinematic parameters (rotational speed and advance speed). The values of these parameters result mainly from the properties of the mineral and the type of mining machine. Therefore, the correct positioning of the holders on the cutting head and their setting (cutting angles) are vitally important. This applies to both the design and implementation stages. For this purpose, the authors first developed models of pick arrangements and, next, the algorithm and software enabling the determination of cutting resistance, both in terms of the average value and its variation. Then, based on the performed calculations and the obtained results, it can be assessed whether the cutting head and the pick arrangement are properly designed. As a result of the performed calculations and analysis of the test results, the average values of the cutting resistance moment and the cutting machine advance forces were determined. It was found that the proposed pick arrangements are characterized by similar values of moments and forces. The greatest differences were found in the variability of these parameters, which translates into the dynamics of the cutting machine operation.

The yielding arch support is transported and installed in the face with the use of auxiliary machines. These activities in underground mining cause many problems, which have as yet not been solved. Currently, transport and assembly are carried out manually, using the roadheader and suspended rail, or various types of mounting platforms. The analysis of the structure of the existing solutions resulted in the development of an original structure that met the requirements of Polish mines. Developed jointly by FAMA Sp. z o.o. and the AGH University of Science and Technology in Krakow, Poland, the mining modular transport and assembly unit (MZT-M) will enable the transport and assembly of support arches in the mining face. Additionally, it can also be used to reload works, which is related to the work ergonomics in underground coal mining, which is the main energy resource in Poland. The most important problem to be solved in the case of this manipulator, due to the limited space in the excavation, is how to ensure its stability during various phases of its operation. Therefore, analyses were carried out to find a solution, which resulted in determining specific conditions and design requirements related to the operation of this manipulator.

The roof support, especially the ŁP yielding steel arch support, is transported and assembled in the face with the use of auxiliary machines. This activity in Polish underground mines causes numerous problems, which until present have not been solved. Currently, transport and assembly are carried out manually, while the roadheader and suspended rail are used only to a small extent. Therefore, the modular installation and transport assembly was developed jointly by FAMA Sp. z o. o. and AGH University of Science and Technology. The solution in question enables performing a number of functions (including transport and assembly of all kinds of support arches), which are not available in currently manufactured equipment. The proposed manipulator solves numerous problems occurring during the installation of the steel arch support in an underground mining excavation and significantly improves the process of drilling galleries. This innovative solution considerably differs from the existing ones, and its greatest advantage is versatility with regard to the cross-section and equipment of the roadway, as well as a wide range of functions. In addition, it can also be used for reloading works. The modular installation and transport assembly together with a platform, a temporary mechanized roof support and a mining machine, make up a mechanizes roadheader complex, which enables continuous mining, loading and installing the permanent support in underground workings.