Archives of Mining Sciences

Detonation of explosives creates strong para-seismic vibrations. Such vibrations can damage buildings or other infrastructure located in the vicinity of such detonations, and can be burdensome to people living in such areas. This paper describes the usefulness of Matching Pursuit (MP) algorithm in assessing the impact of blasting on the surrounding areas, and proves that by taking into account frequency changes over time, vibration analysis can help make much more profound and reliable predictions in this field.

This article presents a comparison of the real amount of structural bending of a traditional residential building on curved mining ground with the bending results from an elastic model of the system: building + ground. Thanks to surveying measurements conducted during the exploitation front, the relationship between the curvature of the building and the curvature of the area in its direct vicinity was determined. The measurement work lasted one and a half years. Observation results collected in nature verify the deformation results of the modelled structure in the approach proposed by the guidelines for designing buildings in mining areas in Poland. Building Research Institute Instructions, Guidelines, Guidance 416 (2006) allows the adoption of an elastic model for the structure, and for the ground, it allows the adoption of linear elastic features characteristic of Winkler elastic ground. The main purpose of the work was to determine the overestimation of stress in the modelled building resulting from the use of a simplified, computational engineering approach.

This paper shows the possibility that the mineral coal existing in the mining basins of northern Spain have a high added value. This would facilitate its future use in different fields such as new materials, nanotechnology, energy use in situ, coal bed methane, enhanced coal bed methane and coalmine methane.

An analytical study of mineral coal samples is carried out. The samples come from two deposits located in coal basins of the Cantabrian Mountains. The duly prepared samples are subjected to an activation process. Within this transformation, different treatments are applied to different sub-samples. Some of the sub-samples suffer a previous demineralization by successive attacks with acids, followed by oxidation and pyrolysis. Finally, all of them are activated with CO2 and H2O(steam).

The carbonaceous products resulting from each treatment are characterised. The results show that all the pre-treatments used were positive for the textural development of the materials. Likewise, proper management of the processes and of the different operating variables allows the procurement of carbonaceous materials with a “tailor-made” structural development of the coal type. This material receives the name “activated” and can be employed in specific processes.

The article presents a comprehensive economic analysis of a CO2 injection project in one of the Polish oil fields for both increased production (CO2-EOR) and underground storage (CCS). An interesting differentiator of this work is the use of a multilayered reservoir, which is actually not one reservoir but several located in the same place, as an example. It allows the optimization of the processes of injection, production and storage. Such projects are becoming more and more important because recently, after a period of long-term stagnation, costs of carbon allowances have started to rise which affects e.g. the electricity market in Poland. This can be an important incentive for the development of CCS technology, especially in combination with CO2-EOR. In the case of very high costs of carbon emissions rights CCS may turn out to be a cheaper solution. Economic efficiency is the main determinant of the EOR project’s success, as well as a very significant factor influencing the potential development of CO2 underground storage. Results are based on the numerical simulation of a combined CO2-EOR and CCS project. This analysis has been divided into two parts. The first uses a standard, deterministic approach, based on the DCF method and NPV indicator. It also provides a detailed sensitivity analysis, with particular reference to the impact of oil prices and the cost of carbon emissions rights on a project’s profitability. The second part of the economic analysis is probabilistic and involves estimating the maximum amount of CAPEX using the Monte Carlo method. Two cases were taken into account. The first assumes that the CO2 emitter pays for CO2 storage and the price is equal to 80% of the emissions rights price (with storage revenue). In the second one the emitter does not pay for storage (without storage revenue).

There is an airflow velocity boundary layer near tunnel wall when the air is flowing in the underground coal mine. The thickness and distribution of the airflow velocity boundary layer could influence the discharge of harmful and toxic gases that enter the ventilating airflow through this flow interface. It may also have a major impact in coal mine gas explosion. The results of field measurements and simulation experimental data are used to research airflow velocity boundary layer in a flat walled mine roadway, which is considered in turn: as unsupported, I-steel sectioned arch or bolted and shot create supported cross section. By referenced to other literature studies that consider boundary layer characteristics and the analysis of on-site and experimental data sets we obtain the corresponding airflow velocity boundary layer characteristics for each of the supported roadway sections. The airflow velocity within the boundary layer increase is assumed to follow a logarithmic law given by the expression: u = a Ln(x) + b. It is concluded that the thickness of the airflow velocity boundary layer is observed to significantly decrease with the airflow center velocity and to increase with roadway wall roughness. The airflow velocity distribution is found to be described by the equation: u = (m1v + n1)Ln(d) + m2v + n2, for the three types coal mine tunnel taking into account the influence of center airflow velocity.

The purpose of this research is to substantiate a technical solution for improving the working conditions for the thermal factor in the extraction of oil by the thermoshaft method using the mine refrigeration technology. The review of manufacturers and technical characteristics of refrigeration technology in Russia, CIS countries and Western Europe was conducted. It was shown that the use of a water cooling machine in the mine air conditioning system will reduce the air temperature in the oil production gallery to the required values and will allow to abandon the long-term construction of a surface stationary refrigeration station. Normalization of the thermal regime reduces the costs of benefits and compensation for work in harmful labor conditions and improves the quality of service of production wells by operators. The practical significance is that the proposed project for the introduction of air conditioning has a high level of profitability, and its payoff will occur in the second year of operation.

Wet shotcrete technology is being gradually used in roadway support in frigid mining areas. Thus, problems such as low strength, fragility, and high repair rate have also emerged. This study focuses on low strength, cracking, and other problems in the wet shotcrete support of a mine. It introduced the fishbone diagram to investigate the effects of temperature, cement content, and water-cement ratio (W/C) on the strength of the shotcrete layer. The microscopic morphology of wet shotcrete based on scanning electron microscopy (SEM) is observed. Results demonstrated that temperature was the main influencing factor of wet shotcrete in frigid mining areas. When the curing temperature was lower than 10°C, the early strength of wet shotcrete dropped significantly. Temperatures above 15°C were favorable for later gain in strength. W/C was of a complementary relationship with strength development at different ages. Temperature was the essential factor that influenced the microscopic morphology of wet shotcrete. Furthermore, internal initial porosity and aggregate interface bonding strength had a direct effect on macro-mechanical properties of wet shotcrete.

Through in-situ stress measurements, stress data were obtained from an auxiliary transportation roadway in a coal mine in Shanxi Province, China. Based on the principles of elastic mechanics and using a generalized plane strain model, the mechanical effects of the in-situ stresses on an idealized roadway were calculated and the distributions of stresses, displacements, and plastic zones determined. Building on this model, the vulnerable zones in the roadway cross section were identified. Ground support specifications were developed and during specification design, comprehensive consideration was given to factors affecting the stability of the rock surrounding the roadway. A scientific and reasonable support scheme was put forward. Practical experience in the coal mine shows the normal forces of anchor bolt and cable, the minimal convergence of roof to floor, and a generally good support in the auxiliary transportation roadway. The support should ensure safe production during its service life. This study provides a new method for designing roadway support systems that can be particularly valuable for high-stress roadways.

In this paper, an attempt was made to find out two empirical relationships incorporating linear multivariate regression (LMR) and gene expression programming (GEP) for predicting the blast-induced ground vibration (BIGV) at the Sarcheshmeh copper mine in south of Iran. For this purpose, five types of effective parameters in the blasting operation including the distance from the blasting block, the burden, the spacing, the specific charge, and the charge per delay were considered as the input data while the output parameter was the BIGV. The correlation coefficient and root mean squared error for the LMR were 0.70 and 3.18 respectively, while the values for the GEP were 0.91 and 2.67 respectively. Also, for evaluating the validation of these two methods, a feed-forward artificial neural network (ANN) with a 5-20-1 structure has been used for predicting the BIGV. Comparisons of these parameters revealed that both methods successfully suggested two empirical relationships for predicting the BIGV in the case study. However, the GEP was found to be more reliable and more reasonable.

The deformation modulus of the rock mass as a very important parameter in rock mechanic projects generally is determined by the plate load in-situ tests. While this test is very expensive and time-consuming, so in this study a new method is developed to combin artificial neural networks and numerical modeling for predicting deformation modulus of rock masses. For this aim, firstly, the plate load test was simulated using a Finite Difference numerical model that was verified with actual results of the plate load test in Pirtaghi dam galleries in Iran. Secondly, an artificial neural network is trained with a set of data resulted from numerical simulations to estimate the deformation modulus of the rock mass. The results showed that an ANN with five neurons in the input layer, three hidden layers with 4, 3 and 2 neurons, and one neuron in the output layer had the best accuracy for predicting the deformation modulus of the rock mass.

Significant differences in the physical and mechanical properties exist between the rock masses on two sides of an ore-rock contact zone, which the production tunnels of an underground mine must pass through. Compared with a single rock mass, the mechanical behavior of the contact zone composite rock comprising two types of rock is more complex. In order to predict the overall strength of the composite rock with different contact angles, iron ore-marble composite rock sample uniaxial compression tests were conducted. The results showed that composite rock samples with different contact angles failed in two different modes under compression. The strengths of the composite rock samples were lower than those of both the pure iron ore samples and pure marble samples, and were also related to the contact angle. According to the stress-strain relationship of the contact surface in the composite rock sample, there were constraint stresses on the contact surface between the two types of rock medium in the composite rock samples. This stress state could reveal the effect of the constraint stress in the composite rock samples with different contact angles on their strengths. Based on the Mohr-Coulomb criterion, a strength model of the composite rock considering the constraint stress on the contact surface was constructed, which could provide a theoretical basis for stability researches and designs of contact zone tunnels.

Salt caverns are used for over 70 years to store power sources and dispose of industrial wastes. The design of cavern shape and dimensions is still considered as a difficult engineering problem despite progress in geotechnical, construction and exploration methods. The rational design of cavern depends on mechanical parameters of rock salt and nonsalt rocks, stability conditions, safety requirements and stored material. However, most of these factors are related to geological factors like depth of cavern location, the geological structure of salt deposit, lithology of interlayers, petrology and mineralogy of rock salt and interlayers. The significant diversity in the geological conditions of different rock salt deposits contributed to the variety in shape and dimensions of salt caverns worldwide.

In this paper, the examples of caverns developed in various salt deposits are presented. The shape of these caverns and its relation to geological features is presented. The influence of geological factors on the formation of irregularities in a cavern shape is described. Moreover, the evaluation of storage caverns located in Polish salt deposits in a view of the aforementioned geological factors is performed. The information and analysis described in this paper provide input which can be useful in future plans connected with the development of underground storage in Poland.

This article presents the results of experimental studies aimed at identifying the forces and acceleration during the riding and braking action of a suspended monorail. The tests were conducted under in situ conditions, in a dip-heading “B” ZG SILTECH in Zabrze. The paper also discusses a test stand, a metering system, and presents the impact of changes in speed on forces in slings of the suspended route. The measurements of selected parameters were performed for three variants: the route, the emergency haulage braking and the braking trolley set braking. The results include waveforms of forces in route slings, and acceleration values acting on the operator and transported load.