User’s choices of conical picks currently involve specifying their material and geometric parameters (functional requirements), incorporating the place and conditions of their work (operational requirements). The selection is usually made based on solely one criterion, which is the price. Thus, at the stage of both purchase and operation, the quality of picks, as well as their matching for a specific machine, are not assessed. The problem of defining whether the producer has fulfilled the user’s requirements arises only when the user questions the picks’ quality. Analysis of this problem has resulted in developing assumptions, concepts and research procedures based on the cutting process requirements. The procedure allows conducting tests to determine the geometric parameters of a pick, the type of material of the pick body and WC-Co insert, as well as the pick wear rate (intensity). The C2 index describes the wear rate (intensity)—the smaller its value, the slower the pick’s wear. Laboratory tests were carried out at the AGH University of Science and Technology in Kraków, Poland. Following the developed method and procedure, the quality of picks was precisely and unambiguously assessed. The C2 index, apart from testing the quality of picks, was also used to forecast their wear. Based on the C2 index, a method is proposed to estimate the wear rate of conical picks provided by different manufacturers and determine the acceptable unit price and operating costs. Thus, it is possible and reasonable to precisely define the investment requirements and appropriately select the pick. Relevant tests were carried out for eight different types of conical picks used in roadheaders, longwall shearers and shaft-boring roadheaders.

The processes of rock formation have long been known and widely described in many literature items worldwide. Due to the multitude of occurring rock types, they are distinguished by various properties. For many decades, scientists worldwide have been determining various parameters by which these properties of rocks can be described. Tests of these parameters are commonly performed in many research centres worldwide. Depending on the scientific discipline, some researchers focus on geological properties (colour, structure, texture, chemical composition). Other researchers focus on physical and mechanical properties: hardness, density, strength properties, compactness, etc. Among them, abrasiveness and abrasivity can also be distinguished. In terms of nomenclature, they are very similar and often confused. Even within the academic community, researchers often use the names interchangeably, which needs to be corrected. This article aims to explain the difference between rock abrasiveness and rock abrasivity, classify methods for their assessment and present their practical applications in the mining and construction industry. It should be emphasized here that abrasiveness is determined when we are interested in the abrasive wear of natural stone and abrasivity when we are interested in the wear of the tool with which we cut the stone. The purpose of this article is also to let the reader decide whether to carry out an abrasiveness or abrasivity test and which method to use.

The longwall system is an extraction system commonly used in coal mining in many countries, including Poland. One of the methods for reducing extraction costs is the dual use of the gateroad. In the first instance, the gateroad serves as the tailgate, and during the exploitation of the second coal panel, it functions as the headgate. Such a situation requires maintenance of the roadway behind the longwall face, which is typically challenging, due to significant stress-related loads on the support and its substantial deformation. The support design for this kind of roadway should take into consideration the dual impact of exploitation pressure and the caved zone influence behind the longwall face. This article presents the results of in-situ research conducted on two roadways behind the longwall face. In both roadways, the effectiveness of specially designed steel arch frames and rock bolt patterns were examined to minimize roadway deformations and maintain their functionality. The research project was comprised of several stages. Initially, mining and laboratory studies were conducted to determine the geomechanical parameters of the rocks. Subsequently, excavation stability and functionality forecasts were performed based on the authors’ empirical indicators. Then, numerical analyses were carried out to design support schemes (steel arches and rock bolt) in both roadways. A fully automated monitoring system with programmed data loggers was designed to check the behaviour of a specific rock mass and the support elements. The load on the steel arch support was measured with the help of load cells, while the load on the rock bolt support was carried out with the help of measurement bolts. Behind the longwall face, the loads on the wooden cribs set from the goaf side were also monitored. Additionally, the measurement station was equipped with extensometers to monitor the movement of roof layers and stress meters to determine changes in rock mass stress. Laser scanning or traditional surveying methods were also used to verify the support schemes through roadway convergence measurements. The obtained results allowed us to draw conclusions regarding the optimization of support schemes and to give recommendations for the practical application of specific reinforcements in excavations maintained behind the longwall face.

During the exploitation of mineral raw materials, a cutting tool is an element that is directly in contact with the unmined stone being cut. The most commonly used cutting tools include conical picks. The increasing pressure to reduce mining costs causes an increasing demand for affordable and reliable ways to increase the reliability of mining machines. Abrasive wear is the most common process affecting the wear of shearer picks, hence a good and simple laboratory method for assessing rocks abrasivity is needed. The new method was developed in the aspect of selection of conical picks with appropriate protection of the pick working part, increasing its durability. The method involves the assessment of mass abrasive wear of a standard steel pin and rock sample, and the determination of the abrasivity index Wz of the tested rock, as the ratio of the mass loss of the steel pin to the mass loss of the rock sample. The article presents the procedure of conducting tests, construction of a laboratory test stand and the use of the developed method to assess the abrasivity of gangue rocks occurring in the currently cut tunnel excavations of Polish hard coal mines.

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.