Key Engineering Materials Vol. 844

Abstract: Two methods of ground improvement have been proposed to overcome excessive and differential settlement problem of soft ground foundation for infrastructure such as road, highway and parking space namely polyurethane (PU) foam and cement grouting slab. It has been executed by excavating and replacing the soft soil at shallow depth with the proposed ground improvement methods. The ground improvement methods able to minimise the excessive and differential settlement as the shallow depth of soft soil is removed and replaced by the stiff materials, thus the load can be distributed evenly to the underlying soil. The comparison of performance between both methods are evaluated in this study by carried out finite element analysis for soft ground problem namely PLAXIS. The results show that the settlement can be reduced significantly to the tolerable amount by applying PU foam instead of cement grouting slab as the increase in thickness of cement grouting slab cause the increase in settlement. On the other hand, the increase in PU foam thickness has not contributed to further settlement as the PU foam is lightweight, however, the soil may experience upward displacement due to insufficient overburden load to counter uplift.

Abstract: The current work deals the phenomenon of non-metallic inclusions as a result of the addition of Yttrium as an alloying component. The order of introducing individual components determines its final content in steel. This problem was analyzed using the WYK_Stal program developed at AGH-UST. Individual cases were considered using the accepted thermodynamics models based on Wagner’s formalism. The study of Y₂O3 and Y₂S₃ phase precipitation and the relationship between the addition of Y, Al, Ca, O and S in molten steel was studied using the thermodynamic models. Based on the simulation, the authors stated that, the introduction of aluminum as the final deoxidizer into the liquid steel before the yttrium, results in the formation of non-metallic oxide inclusions. The low oxygen content in the metal bath promotes the formation of yttrium sulphide. In the case of calcium dosing, it is reasonable that, the yttrium is introduced after this element, which limits the losses on the formation of the yttrium sulphide phase.

Abstract: Ground improvement methods are carried out to enhance the soil properties in order to ensure the unsuitable site locations with poor soil conditions can be developed for future development. Injection of lightweight material namely polyurethane foam is found to be one of the alternative methods that provide cost-effective and reliable techniques for ground improvement. Petroleum-based polyurethane is widely used in geotechnical application but nowadays the cost is getting more expensive due to high depleting rate and high production cost. Instead of using petroleum-based PU, this study is focusing on performance of palm kernel oil-based PU as an alternative method for ground improvement. The palm kernel oil-based polyurethane foam is anticipated to be more economical since it is produced from the renewable source, where it does not lead to permanent depletion of resources which has a limited global availability. The objective of this study is to determine the expansion and compressibility of palm kernel oil-based polyurethane with different mixing ratio. The samples were tested using Rowe cell apparatus to determine the compressibility, swelling index and pre-consolidation pressure of the polyurethane. The results of the finding show that the expansion and compressibility of the palm kernel oil-based polyurethane foam varies with the mixing ratio of isocyanate and polyol liquid. The compressibility index of PKO-BPU is found to be higher than petroleum-based polyurethane and low in expansion.

Abstract: Aluminum has mechanical properties such as light, easy to form, and the ability to conduct heat and electricity, but has less corrosion resistance properties. One effort to improve corrosion resistance in aluminum is by electrodeposition method. The electrodeposition process was carried out with a variation of time 10, 20, and 30 minutes and variations in voltage of 5 V, 10 V, and 15 V using AA 1100. The electrolyte used was a mixture of acetic acid and chitosan. Coating thickness measurement was carried out using NOVOTEST TP-1M coating thickness gauge, the corrosion rate was measured with 128N Autolab PGSTAT Potentiodynamic and surface roughness measurements using Mitutoyo SJ-210 Surface Roughness Tester. Based on the research data, it was found that the results of optimum layer thickness were obtained at 10 Volt variation of 20 minutes at 11 μm ± 0.04%. Specimens without treatment had the highest corrosion rate of 0.25541 mpy while the lowest corrosion rate was in the 10 variations of 20 minutes which produced 0.0078935 mpy. The surface roughness data of the specimen without treatment was 1.034 μm. The results of the smallest surface roughness were obtained at 10 V 20 minutes variation of 0.725 μm, while the largest surface roughness results in a variation of 15 V 30 minutes which was 2.529 μm. In this stud, it is known that the higher the time and stress used in the electrodeposition process results in greater corrosion rates, because it produces a higher layer thickness but results in higher surface roughness as well.

Abstract: Results of evaluating the suitability of certain sections of Western Donbas coal seams, based predominately on properties of coal material, for their further experimental development by means of underground gasification method are represented. Criteria to evaluate both expediency of underground gasification and specific conditions of that process are substantiated basing upon the methodology developed at the National Mining University (Dnipro, Ukraine) together with representatives from National University of Saint Augustine (Arequipa, Peru). The methodology has been industrially approved with the confirmation of its efficiency while developing technical documentation for underground gasification projects: “Project of experimental section of Pidzemgaz station of Pavlogradvuhillia association”, “Feasibility study of the expediency of the construction of Pidzemgaz station” FS 3858-PZ”, Synelnykovo deposit; “Project on experimental underground gas generator”, Monastyryshche deposit, FS of experimental module of UCG station of Solenovske coal-mining area, Donbas. Also, they contain the researches, which were conducted within the project GP – 489, financed by Ministry of Education and Science of Ukraine.

Abstract: This paper is devoted to the history of exploration of sintezed and natural gas hydrate. Academic, engineering and energy periods of the history of gas hydrates studies are described. The most significant researches in this area are described. The main practical projects in the world for the study and production of gas hydrates are reviewed.

Abstract: It has been demonstrated that shock-vibrating activation of minerals is a prospective method to impact the ore; it may be used to intensify chemical and physical-chemical processes of mineral raw material processing and preparation. Differences in the composition and phase properties, obtained both in terms of continuous and periodic modes, are in the fact that in the first case loadings deal with interlayer space preserving layered nature of the mineral. When the mode is continuous, then the disturbances cover the octahedral layer though elementary constituent – tetrahedrons – are preserved. It has emerged that the most important advantage of high reacting capability of activated minerals is in the fact that leaching of some ores may be performed in chlorhydric acid at the expense of transformation of some silicate components into a specific state – loose packing of basic silicate chain. Consequently, shock-vibrating activation has become a basis to develop a method of leaching process intensification as well as a method to control phase formation.

Abstract: According to the materials of the Rivne exploration expedition in Rivne region more than 15.3 million tons of phosphogypsum materials in rock dumps are stored. For further use and recycling of waste, it is necessary to evaluate the content of rare earth elements in phosphogypsum, which are of considerable economic value. The possible recycling of this production will increase the level of environmental safety through the use of more reliable engineering systems for the environmentally safe storage of phosphogypsum rock dumps. The migration of phosphorus, fluorine, sulfur, copper, chromium, manganese, zinc, lead, cadmium, iron, nickel and cobalt along the profile of the artificial ground cross-section was investigated experimentally. The results of studies confirmed the increased accumulation of metal in the phosphogypsum rock dumps. Analyzing the content of nickel, lead, sulfur, manganese, cobalt and zinc in experimental samples, we observe the distribution pattern, the content of which in samples is 2 – 3 times higher than the content of trace elements of the above-mentioned groundwater deposits. The results of the sorption and desorption of nickel, lead, sulfur, manganese, cobalt and zinc indicate that the rock is not an obstacle to the migration of trace elements and its aggregates in the rock and is observed only in the zone of full water saturation due to the filling of pore space. The conducted researches established the presence of phosphogypsum in man-made wastes of nickel, lead, cobalt, zinc, iron with a percentage content up to 1% per ton of rock waste.

Abstract: Development of a waste-free technology for lignite slurry upgrading at briquetting factories, which provides for getting cleared water for closed-loop water supply and transportable product for burning or briquetting with sustainable equipment application. Detection and study of peculiarities of lignite coal and slurry of briquetting factories, as well as research on slurry surface properties for substantiating a separation ratio. Determination of the separation ratio of lignite coal slurry taking into account its surface properties to estimate technological efficiency of reagentless flotation separation. Research on kinetics of settling and influence of different flocculants on efficiency of the slurry thickening process for sludge collection and getting circulating water. Development of waste-free technology for lignite slurry upgrading with the purpose of slurry recycling based on the substantiation of rational technological parameters and appropriate equipment. Regularities of the process of reagentless flotation separation of lignite coal slurry, kinetics of settling are defined, which is the basis of technological solutions on separate briquetting waste treatment. A waste-free technology for upgrading lignite slurry and cinders with closed-cycle of water supply and transportable final product for burning and briquetting with moisture content of 26% ... 28 % is developed. Floating and sinking fractions of lignite slurry are studied and necessity of separate treatment of these fractions is substantiated. Kinetic regularities of deposition of heat-treated lignite particles are determined; rational modes which provide for efficient deposition of particles of the sinking fraction with minimum flow of a flocculant are defined. A phenomenon of hydrophobic behaviour of mineral particle surface after heat treating and briquetting of lignite coal is revealed, which is taken as a separation ratio; this allowed substantiating the waste-free technology for lignite slurry upgrading through reagentless flotation separation. The practical value of the results obtained involves development of a waste treatment technology at a briquetting factory (slurries and cinders) and its conversion into closed-loop water supply, which will allow obtaining 23 t/year of transportable final product additionally as well as decreasing consumption of pure water considerably and eliminating environment pollution.