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Abstract

In the paper, the extended finite element method (XFEM) is combined with a recovery procedure in the analysis of the discontinuous Poisson problem. The model considers the weak as well as the strong discontinuity. Computationally efficient low-order finite elements provided good convergence are used. The combination of the XFEM with a recovery procedure allows for optimal convergence rates in the gradient i.e. as the same order as the primary solution. The discontinuity is modelled independently of the finite element mesh using a step-enrichment and level set approach. The results show improved gradient prediction locally for the interface element and globally for the entire domain.
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Abstract

The paper presents the response of a three-layered annular plate with damaged laminated facings to the loads acting in their planes. The presented problem concerns the analysis of the combination of global plate failure in the form of buckling with the local micro defects, like fibre or matrix cracks, located in the laminas. The plate structure consists of thin laminated, fibre-reinforced composite facings and a thicker foam core. The matrix and fibre cracks of facings laminas can be transversally symmetrically or asymmetrically located in plate structure. Critical static and dynamic stability analyses were carried out solving the problem numerically and analytically. The numerical results show the static and dynamic stability state of the composite plate with different combinations of damages. The final results are compared with those for undamaged structure of the plate and treated as quasi-isotropic ones. The analysed problem makes it possible to evaluate the use of the non-ideal composite plate structure in practical applications.
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Abstract

The article presents the methodology to estimate the operator influence on measurements performed with a coordinate measuring arm. The research was based on the R&R analysis, adapted to the specifics of redundant devices such as ACMM (selection of a test object difficult to measure). The method provides for measurements by three operators, who measure ten parts in two or three samples (measurement data developed in the article relate to the three measurements of holes). The methodology is designed to identify which operator has the best predisposition to perform measurements (generates the smallest measurement errors). Statistica software was used to analyse and visualize measurement data.
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Abstract

At the current stage of diagnostics and therapy, it is necessary to perform a geometric evaluation of facial skull bone structures basing upon virtually reconstructed objects or replicated objects with reverse engineering. The objective hereof is an analysis of imaging precision for cranial bone structures basing upon spiral tomography and in relation to the reference model with the use of laser scanning. Evaluated was the precision of skull reconstruction in 3D printing, and it was compared with the real object, topography model and reference model. The performed investigations allowed identifying the CT imaging accuracy for cranial bone structures the development of and 3D models as well as replicating its shape in printed models. The execution of the project permits one to determine the uncertainty of components in the following procedures: CT imaging, development of numerical models and 3D printing of objects, which allows one to determine the complex uncertainty in medical applications.
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Abstract

The article presents the issue of calibration and verification of an original module, which is a part of the robotic turbojet engines elements processing station. The task of the module is to measure turbojet engine compressor blades geometric parameters. These type of devices are used in the automotive and the machine industry, but here we present their application in the aviation industry. The article presents the idea of the module, operation algorithm and communication structure with elements of a robot station. The module uses Keyence GT2-A32 contact sensors. The presented information has an application nature. Functioning of the module and the developed algorithm has been tested, the obtained results are satisfactory and ensure sufficient process accuracy. Other station elements include a robot with force control, elements connected to grinding such as electrospindles, and security systems.
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Abstract

An optimal sensor placement methodology is implemented and herein proposed for SHM model-assisted design and analysis purposes. The kernel of this approach analysis is a genetic-based algorithm providing the sensor network layout by optimizing the probability of detection (PoD) function while, in this preliminary phase, a classic strain energy approach is adopted as well established damage detection criteria. The layout of the sensor network is assessed with respect to its own capability of detection, parameterized through the PoD. A distributed fiber optic strain sensor is adopted in order to get dense information of the structural strain field. The overall methodology includes an original user-friendly graphical interface (GUI) that reduces the time-to-design costs needs. The proposed methodology is preliminarily validated for isotropic and anisotropic elements.
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Abstract

Centrifugal pumps are used for different applications that include pressure boosting, wastewater, water supply, heating and cooling distribution and other industrial processes. This paper presents theoretical and experimental investigations of mechanical vibrations of a centrifugal pump. The flow in this pump, which induces pressure pulsations and mechanical vibrations, have been monitored. Vibration measurements and data collection (overall vibrations levels and frequency spectrum) were extracted from the system. In addition, one of the methods used to study vibration amplitudes for this pump is forced response analysis. To study and analyze the pump system, the finite element analysis software (ANSYS) was applied. Depending on the analysis performed and investigations outcomes, the system natural frequency coincides with the vane-pass frequency (VPF) hazardously. To attenuate the system’s vibration, a vibration control element was used. The vibration levels were reduced by a factor of 2 for a tuned element as obtained from a forced harmonic response analysis of the pump system with absorber. It is shown that the inserted element allows the centrifugal pump to work in a safe operating range without any interference with its operation.
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Abstract

The article presents the socio-environmental policy of the selected entities operating in the rock raw materials industry. Integrated reports prepared by mining entrepreneurs may be a source of verification of the “raw materials policy”, identified as a manifestation of the care of these entities for the environment and society. Rational deposit management is closely related to the raw material policy. The preparation of integrated reports is compulsory from as of January 2017 (in accordance with Directive 2014/95/EU) for large companies in the EU. These are companies that fulfil the criterion of the number of employees (500 persons for public interest entities required under the Directive to extend non-financial information) and the balance sheet total (>EUR 20 million EUR) or net income (>EUR 40 million EUR). This obligation mainly applies to mining enterprises involved in mining and processing hard coal, lignite or copper ore. The mining of non-energy raw materials is no less important. The rock raw materials are used, among others, in road construction, railways or construction, in the form of aggregates, and stone elements, and also in the paper, cosmetic and ceramic industries. The article aims to analyseanalyze the socio-environmental policy of mining entrepreneurs dealing with the exploitation of rock raw materials in accordance with latest GRI guidelines (Global Reporting Initiative – G4). The scope of activities was compared in accordance with the principles of sustainable development of three large companies operating in the Polish mining industry: Cemex, Górażdże Heidelberg Cement Group and Lafarge. They compared the extent to which and the form in which non-financial data are is presented. It was presented and included which of the mentioned companies take into account the full value chain in the reporting process, from mining operations to processing and sale products, into account.
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Abstract

This investigation is concerned with the extraction of nugget copper particles from copper recovery plant slag which recycled of copper scrap. For this purpose, the Falcon concentrator was used because of its enhanced gravity properties. The Falcon concentrator has a fast spinning bowl which creates a centrifugal force to separate fine size minerals on the basis of their density differences. In the tests, the tailings of the copper recovery plant were used and the test sample was divided into two groups and one of them was classified in narrow particle sizes. The operational parameters were determined as particle size, centrifugal force and washing water pressures. The water pressure and centrifugal force have an inversely proportional relationship. Because of this phenomenon, the G/P parameter was created. The test conditions were applied to the whole distribution sample and narrow size distribution samples in the same way. The test results indicate that the average grade was elevated from 1.04% to 6.50% with the recovery of 15.07% and 619% enrichment ratio for narrow sizes, whereas grade was elevated to 4.36% with 13.24% recovery and 415.94% enrichment ratio for the whole distribution. As a result, the recovery and grade values of concentrates are not good enough for gravity concentration process for both samples. However, this process was applied to the double recycled material and the lower recovery, grade values can be tolerated because of concentrate is nugget copper metal. The concentrate can also be washed in cleaning table for increasing the grade value for adding to initial feed of plant. This process can, therefore, supply important earnings not only economically but also environmentally.
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Abstract

One of the most critical aspects of mine design is to determine the optimum cut-off grade. Despite Lane’s theory, which aims to optimize the cut-off grade by maximizing the net present value (NPV), which is now an accepted principle used in open pit planning studies, it is less developed and applied in optimizing the cut-off grade for underground polymetallic mines than open pit mines, as optimization in underground polymetallic mines is more difficult. Since there is a similar potential for optimization between open pit mines and underground mines, this paper extends the utilization of Lane’s theory and proposes an optimization model of the cut-off grade applied to combined mining-mineral processing in underground mines with multi-metals. With the help of 3D visualization model of deposits and using the equivalent factors, the objective function is expressed as one variable function of the cut-off grade. Then, the curves of increment in present value versus the cut-off grade concerning different constraints of production capacities are constructed respectively, and the reasonable cut-off grade corresponding to each constraint is calculated by using the golden section search method. The defined criterion for the global optimization of the cut-off grade is determined by maximizing the overall marginal economics. An underground polymetallic copper deposit in Tibet is taken as an example to validate the proposed model in the case study. The results show that the overall optimum equivalent cut-off grade, 0.28%, improves NPV by RMB 170.2 million in comparison with the cut-off grade policy currently used. Thus, the application of the optimization model is conducive to achieving more satisfactory economic benefits under the premise of the rational utilization of mineral resources.
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Abstract

The worldwide consumption of wollastonite has been increasing from day to day. It is a calcium metasilicate with the chemical formula CaSiO3. Wollastonite is the only naturally occurring, nonmetallic, white mineral that is needle-shaped in a crystal habit. Due to its high chemical and thermal resistance and nontoxic properties, wollastonite replaces asbestos. Apart from this, the acicular property of wollastonite allow it to compete with other acicular materials where improvements in dimensional stability, flexural modulus and heat deflection are sought. Due to its unique properties such as: its high brightness and whiteness, low moisture and oil absorption, low volatile content, and acicular properties, it is used also as a filling material for ceramics, plastics and paints, thermal and electrical insulator, wetting agent and smelter for glaze. Three methods are used for the beneficiation of wollastonite: mechanical sorting, dry or wet magnetic separation and flotation. Magnetic separation and flotation can be applied together in some cases. In this study, flotation has been investigated for the selective separation of calcite-rich wollastonite ores from the Buzlukdağ deposit, in the Kırşehir-Akpınar region, in the middle of Anatolia. The mineralogical analysis of the sample used in the study shows that the ore sample contains 60–62% wollastonite (CaSiO3), 4–5% augite (Ca,Na)(Mg,Fe,Al)(Si,Al)2O6, 30–32% calcite (CaCO3) and minor amount of other minerals. As a result of this study, the wollastonite concentrate which contains 0.44% Fe2O3, 52.71% SiO2, 87.85% wollastonite with 0.60% loss on ignition (using 1500 g/t potassium oleate) was obtained. The ultimate grade concentrates of calcite that can also be obtained as by-products are with 99.80% calcite content and 85.4% recovery.
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Abstract

In order to prepare a coal company for the development of future events, it is important to predict how can evolve the key environmental factors. This article presents the most important factors influencing the hard coal demand in Poland. They have been used as explanatory variables during the creation of a mathematical model of coal sales. In order to build the coal sales forecast, the authors used the ARMAX model. Its validation was performed based on such accuracy measures as: RMSE, MAPE and Theil’s index. The conducted studies have allowed the statistically significant factors out of all factors taken into account to be identified. They also enabled the creation of the forecast of coal sales volume in Poland in the coming years. To maintain the predictability of the forecast, the mining company should continually control the macro environment. The proper demand forecast allows for the flexible and dynamic adjustment of production or stock levels to market changes. It also makes it possible to adapt the product range to the customer’s requirements and expectations, which, in turn, translates into increased sales, the release of funds, reduced operating costs and increased financial liquidity of the coal company. Creating a forecast is the first step in planning a hard coal mining strategy. Knowing the future needs, we are able to plan the necessary level of production factors in advance. The right strategy, tailored to the environment, will allow the company to eliminate unnecessary costs and to optimize employment. It will also help the company to fully use machines and equipment and production capacity. Thanks to these efforts, the company will be able to reduce production costs and increase operating profit, thus survive in a turbulent environment.
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Abstract

The paper analyzes the impact of potential changes in the price relation between domestic and imported coal and its influence on the volume of coal imported to Poland. The study is carried out with the application of a computable model of the Polish energy system. The model reflects fundamental relations between coal suppliers (domestic coal mines, importers) and key coal consumers (power plants, combined heat and power plants, heat plants, industrial power plants). The model is run under thirteen scenarios, differentiated by the ratio of the imported coal price versus the domestic coal price for 2020–2030. The results of the scenario in which the prices of imported and domestic coal, expressed in PLN/GJ, are equal, indicate that the volume of supplies of imported coal is in the range of 8.3–11.5 million Mg (depending on the year). In the case of an increase in prices of imported coal with respect to the domestic one, supplies of imported coal are at the level of 0.4–4.1 million Mg (depending on the year). With a decrease in the price of imported coal, there is a gradual increase in the supply of coal imports. For the scenario in which a 30% lower imported coal price is assumed, the level of imported coal almost doubles (180%), while the supply from domestic mines is reduced by around 28%, when compared to the levels observed in the reference scenario. The obtained results also allow for the development of an analysis of the range of coal imports depending on domestic versus imported coal price relations in the form of cartograms.
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Abstract

The research was aimed at examining the impact of the petrographic composition of coal from the Janina mine on the gasification process and petrographic composition of the resulting char. The coal was subjected to fluidized bed gasification at a temperature below 1000°C in oxygen and CO2 atmosphere. The rank of coal is borderline subbituminous to bituminous coal. The petrographic composition is as follows: macerals from the vitrinite (61.0% vol.); liptinite (4.8% vol.) and inertinite groups (29.0% vol.). The petrofactor in coal from the Janina deposit is 6.9. The high content of macerals of the inertinite group, which can be considered inert during the gasification, naturally affects the process. The content of non-reactive macerals is around 27% vol. The petrographic analysis of char was carried out based on the classification of International Committee for Coal and Organic Petrology. Both inertoid (34.7% vol.) and crassinetwork (25.1% vol.) have a dominant share in chars resulting from the above-mentioned process. In addition, the examined char contained 3.1% vol. of mineroids and 4.3% vol. of fusinoids and solids. The calculated aromaticity factor increases from 0.75 in coal to 0.98 in char. The carbon conversion is 30.3%. Approximately 40% vol. of the low porosity components in the residues after the gasification process indicate a low degree of carbon conversion. The ash content in coal amounted to 13.8% and increased to 24.10% in char. Based on the petrographic composition of the starting coal and the degree of conversion of macerals in the char, it can be stated that the coal from the Janina deposit is moderately suitable for the gasification process.
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Abstract

The reports of Intergovernmental Panel for Climate Change indicate that the growing emission of greenhouse gases, produced from the combustion of fossil fuels, mainly carbon dioxide, leads to negative climate changes. Therefore, the methods of mitigating the greenhouse gases emission to the atmosphere, especially of carbon dioxide, are being sought. Numerous studies are focused on so-called geological sequestration, i.e. injecting carbon dioxide to appropriate geological strata or ocean waters. One of the methods, which are not fully utilized, is the application of appropriate techniques in agriculture. The plant production in agriculture is based on the absorption of carbon dioxide in the photosynthesis process. Increasing the plant production directly leads to the absorption of carbon dioxide. Therefore, investigation of carbon dioxide absorption by particular crops is a key issue. In Poland, ca. 7.6 mln ha of cereals is cultivated, including: rye, wheat, triticale, oat and barley. These plants absorb approximately 23.8 mln t C annually, including 9.8 mln t C/yr in grains, 9.4 mln t C/yr in straw and 4.7 mln t C/yr in roots. The China, these cereals are cultivated on the area over 24 mln ha and absorb 98.9 mln t C/yr, including 55 mln tC/yr in grains, 36 in straw, and 7.9 mln t C/yr in roots. The second direction for mitigating the carbon dioxide emission into the atmosphere involves substituting fossil fuels with renewable energy sources to deliver primary energy. Cultivation of winter cereals as cover crops may lead to the enhancement of carbon dioxide removal from the atmosphere in the course of their growth. Moreover, the produced biomass can be used for energy generation.
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Abstract

The subject of the research was the Middle Miocene red algal limestone from the Włochy deposit, which is currently the only place of exploitation of the Pińczów Limestone representing a local type of the Leitha Limestone. The collected samples of this rock belong to the organodetric facies of diverse grain size and sorting of clastic material. Considering the proportions of characteristic skeleton remains, the composition of the coarse-grained organodetric facies is red algal-foraminiferalbryozoic, while of the fine-grained facies is foraminiferal-red algal. The cement of these rocks is predominantly sparite compared to micrite-clay matrix. A complement to petrographic studies was the chemical analysis and identification of mineral phases with X-ray diffraction. Moreover, physical and mechanical properties of samples were analyzed. Porosity of the rock was assessed in the polarizing and scanning microscope (SEM-EDS) observations, as well as with a porosimetric tests. The coarse-detrital limestone with a dominant binder in the form of intergranular cement is characterized by the apparent density sometimes exceeded 1.90 Mg/m3, while fine-grained limestone has the highest water absorbability (above 20%) and total porosity (about 40%). The above properties influenced high water absorption by capillarity, limiting the possibility of using limestone in places exposed to moisture. The observed relationship between the ultrasonic waves velocity and the uniaxial compressive strength gives the possibility of predicting the value of the latter parameter in the future. The limestones from Włochy deposit do not differ in quality from the previously used Pińczów Limestones, and their technical parameters predestine them for use as cladding material with insulating properties.
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Abstract

In recent years, more and more attention has been paid to the quality of produced coal size categories for energy purposes. This is important from the perspective of promoting clean coal technologies which aim at changing the perception of coal as a fuel friendly for the environment. This is specifically because hard coal resources in Poland allow the national energy security to be guaranteed on the basis of energy production based on hard coal. Fine coals upgraded at coal processing facilities in the separation process in fine coal jigs are mainly used in energy production from coal. In the article, an analysis of hard coal upgrading in a jig regarding the optimum recovery of a useful fraction in the concentrate (combustible and volatile matter) and non-useful fraction in tailings (ash and sulfur) was conducted. Based on the industrial testing of a fine coal jig, the granulometric and densimetric analysis of the taken samples of concentrate, middlings and tailings of coal was conducted in laboratory conditions. Yields of products were calculated in separated size-fractions of separation products, and ash content and total sulfur content were determined in them. Based on the results of granulometric, densimetric and chemical analyses of the obtained size-fractions, the balance of separation products and appropriate calculations, Fuerstenau upgrading curves which allowed the process to be evaluated and a comparison of the results of hard coal upgrading regarding the optimum recovery of the organic phase in the concentrate and mineral components in tailings to be drawn. The obtained results were evaluated on the basis of different criteria for changing the device’s hydrodynamic operational conditions. The ash content and total sulfur content were analyzed as non-useful substances.
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