In this article, experimental research on rotary drilling into limestone and granodiorite samples, conducted on a horizontal drilling rig constructed at the Institute of Geotechnics of the Slovak Academy of Sciences, is described. Drilling into limestone and granodiorite was conducted using two surface set core diamond drill bits with diamonds of different sizes but identical drill bit contact areas. The purpose of the experiments was to obtain data on the wear of drilling tools, in particular by changing the type of the rock used in the drilling experiments. Initial drilling was conducted into limestone, and after drilling the length of 6.75 meters, the drilling was conducted into granodiorite, the rock with higher abrasivity. The findings observed with the use of granodiorite included more significant changes in the shape and abrasion degree of the diamonds embedded in the drilling tools. For the purpose of the assessment of the condition of the surface set diamond drill bits, the penetration depth and torque parameters were measured during experimental drilling, and subsequently used to calculate the values of specific energy. Rock debris generated by drilling was collected and subjected to a sieve analysis in a laboratory. Results of the sieve analysis were used to calculate the coarseness index (CI) in order to compare the changes in the rock debris particle size. It was examined whether the changes in the shapes and condition of the diamonds embedded in drill bits affected the process parameters and the rock debris particle size. The objective was to identify the effects of deterioration of the drilling elements of the surface set diamond drill bits on the values of the yield of rock debris of all fractions, as well as its effects on the penetration depth and specific energy values. It was observed that the tested drill bits exhibited comparable values of the yield of rock debris of all fractions after drilling into limestone to identical penetration depths. The difference in the calculated CI values observed for the drill bit with larger diamonds during the first conducted drilling into granodiorite was more significant that that observed with the use of the bit with smaller diamonds. The resulting comparison of the drilling tools, in particular the respective values of the penetration depth and the CI calculated based on the analysed rock debris, revealed that the surface set drill bit with smaller embedded diamonds was more suitable for drilling into limestone as well as granodiorite.

Deployment of a tunnel boring machine (TBM) for excavation of tunnel structures in particular rock mass environment requires to provide an efficient TBM advance rate by application of the proper excavation regime. The applied regime has to respond to the changes in the excavated rock mass and to the wear of cutting discs installed on the TBM cutterhead. The paper describes a method for the control of excavation efficiency using the excavation process variables monitored during the TBM operation, with subsequent calculation of specific cutting energy, contact pressure of cutting discs and theoretical torque of the TBM cutterhead.

This study analyzes laboratory rock drilling of andesite and limestone using an experimental drilling rig. The description of mechanical rock disintegration was based on defining the properties of the drilled rocks, describing the measured vibrations, calculating the output parameters of the rock disintegration, and comparing them under different drilling regimes using the same drilling tool. Experiments were conducted using two three-channel surface-set diamond core drill bits with identical diamond sizes. The rock disintegration performance was assessed using the measured output variables, which were torque and penetration rate of the drill bit. From these, the specific energy and drilling strength were calculated. Vibration diagnostics were based on the measured vibration acceleration signal. The primary aim of the experimental research was to gain insight into how changes in thrust force and rotational speed (controllable input variables) affect the size of the drill debris and vibrations for the selected rock-tool system. The energy intensity of drilling andesite and limestone was evaluated using specific energy and rock debris. The rock debris was assessed using the coarseness index CI and the absolute size constant d′, employing the Rosin–Rammler method. Comparing drilling into two different types of rocks, limestone and andesite, resulted in a more precise classification of the rock debris, vibration emissions, and their relationships. The drilling of andesite and limestone was analyzed by calculating the overall vibration level in the 4,000-9,000 Hz frequency range using the power spectral density function. This evaluation considered variations in the constant drilling regime and was compared with the specific energy values obtained and the calculated inflection point. The inflection point indicates the start of the efficient disintegration region, where chipping occurs. It was found that evaluating only axial vibrations to describe the rock disintegration region is insufficient; it is also necessary to monitor lateral and torsional vibrations for a more comprehensive understanding of the rock-tool interaction. The results included comparisons of the power spectral density in the high-frequency range with the coarseness index (CI) and the ratio of specific energy to drilling strength. In the high-frequency range of 6,500 Hz, the rock-tool interaction was characterized by higher power spectral density, increased coarseness index, and decreased drilling strength observed during limestone drilling.

Bentonite is widely used as a sorbent due to its high specific surface area and ion-exchange capacity; however, its properties can be significantly influenced by the presence of additional mineral phases and chemical modification. In this study, the influence of manganese oxides and quartz sand on the sorption properties of bentonite from the Stará Kremnička was systematically investigated, with particular attention to surface characterization by X-ray photoelectron spectroscopy (XPS). The materials were also characterized by X-ray diffraction, FTIR spectroscopy, and zeta potential measurements. XPS analysis revealed that manganese in all modified samples was predominantly present in the Mn(IV) oxidation state, with Mn 2p₃/₂ binding energies of 642.5–642.7 eV, corresponding to MnO₂-type phases. Deconvolution of the O 1s spectra confirmed the presence of lattice oxygen, silicate oxygen, and surface hydroxyl groups. The reason for the modification of mainly natural materials with manganese oxides is their higher affinity for the adsorption of heavy metal cations. The maximum adsorption capacity of natural bentonite was 63.29 mg/g. In bentonite samples modified with manganese oxides, the value increased to 103.09 mg/g for BMn, and to 116.28 mg/g for the MMn mixture. The results demonstrate that sorption behavior is governed by a combination of ion exchange on bentonite and interactions with Mn oxide surface phases, providing new insight into the role of Mn(IV) species in surface-controlled metal binding processes. These findings highlight the importance of surface chemical states in designing efficient bentonite-based sorbents.

For the purpose of exact identification of factors affecting the drilling process and their effects in in - situ conditions as well as identification of correlations between input and output parameters, it is important to examine the cutting process through the laboratory research. The article presents the developed analytical solutions of the correlation between torque and penetration depth as a function of thrust force. They are based on the processing of the data obtained from drilling andesite on an experimental laboratory stand using surface set core diamond drill bits. A large archived database facilitated analysing the correlations between the measured and model data. The analysis of the derived mathematical models for the torque and penetration depth also brought to light new information on the factors affecting the cutting process of rock and facilitated the identification of their effects on a drilling tool. The theoretical values of torque and penetration depth, which were calculated using the created analytical solutions, exhibited a very high level of correlation with the experimental data. It was found that the values for the torque and penetration depth were affected by the number of actively working diamonds and by their size. Penetration depth per unit of thrust force at the given contact surface strength exponentially decreased with an increasing drilled length. The ratio of coefficients α/κ proportionally increased with an increasing contact surface strength. In the chipping zone of rock cutting, there was a linear correlation between torque and penetration depth. The thrust force required to achieve chipping in a rock cutting process increased as the wear of drill bits increased.

This study focuses on characterizing the shape of drill cuttings produced during drilling in limestone, andesite, and granodiorite. These rock debris particles were collected in containers during drilling as a result of rock disintegration . The drill cuttings were analyzed using wet - sieve analysis with six sieves of different mesh sizes. The rock debris was divided into seven classes. When evaluating particle shape, we focus on the second class, which has the largest particles, ranging from 400 μm to 1000 μm, but accounts for the lowest percentage of the total weight of drilling debris. Particle size distribution was measured using the Camsizer X2 particle size and shape analyzer (Retsch , Germany) with dual camera technology and an X - dry sample feeder. From data obtained from the particle analyzer, we evaluated particle shape using diagrams by Sneed & Folk, which categorize drill cuttings into seven descriptive classes. Through this analysis, we aimed to gather information about the interaction between rocks and surface - set diamond core drill bits. The aim was to monitor changes in the shape and size of particles from the analyzed larger rock fragments after drilling rock samples. Changes in particle size relative to their shape were assessed using a cal culated shape coefficient. The coefficient is represented by a single number for each rock specimen. Using the coefficient, we can identify changes in the constant drilling regimes, including the drilled length and the type of drilling tool used. Such an assessment of particle shape would help provide a more detailed evaluation of the selection of drilling tools and their wear .