Papers by Keyword: Composition

Abstract: A large amount of finely dispersed manganese ore left after benefication operations or blown out from the furnaces is unsuitable for direct use in electric furnaces and blast furnaces, therefore it is necessary to granulate it in order to have the efficient use of its fine ore particles in metallurgy. To make our research more of practical use, we found it is reasonable not only work over manganese fines sintering but also to attempt mitigating the negative effect on the environment produced by the further sintering and apply the biofuel within the total fuel mass. Under laboratory conditions, the studies have been carried out with the objective to obtain manganese sinter, in which wood biomass is applied, namely initial and pre-pyrolyzed, at temperatures of 673, 873, 1073 and 1273 K. The amount of biofuel in the sinter blend was 25 wt.%. It has been established that the biomass use causes the decrease in the specific capacity of the sintering plant. However, for the efficient manganese ores sintering process, the biofuel of high pyrolysis temperature of 1273 K is required. To achieve the specific capacity and the yield to be as high as those when coke breeze is only used, the amount of the biofuel for manganese ore sintering should be less than 25 wt.% of the solid fuel. Additionally, it has been revealed that the further increase in the biofuel ratio in the total fuel amount is possible on condition that its reactivity is decreased, or larger particles of the biofuel are used.

Abstract: It was determined that the current method of the Bakalsk mining department siderite ore preparation for blast-furnace smelting does not allow production of concentrate meeting the state-of-the-art metallurgy requirements. The most perspective method is reducing firing when a metallized product with higher iron content is obtained. It was demonstrated that implementation of this method requires the use of a three-zone shaft furnace having the oxidizing roasting zone, the reduction zone and the reduced product cooling zone. Experiments were carried out on the siderite ore reducing firing on laboratory units. The possibility in principle was demonstrated for production of the reduced product with iron content of 60 – 65% from the siderite ore. After the magnetic dressing the concentrate with iron content of 65 – 75% was obtained. It was determined that firing and reduction in hydrogen atmosphere result in the fired product reduction degree of 97 %. The possibility to produce a product suitable for blast-furnace conversion with the reduction degree of about 60% with the use of natural gas air conversion gas was demonstrated. The obtained results were used in the process development for the siderite ore reducing firing in a three-zone shaft furnace.

Abstract: High-entropic magneto-plum-bite structured crystal phases were theoretically calculated and then prepared by solid state synthesis. The compositions and formation conditions for by-product, such as spinel structured multicomponent crystals, that had not been previously described in literature, were analyzed. The list of elements which can be the main components of such phases was defined. Important conclusions about the conditions for growing high-entropy crystals from melts were made. Particularly, it was shown that the obligatoriness for additional oxidation of the melt should be taken into account (relative to the level that the composition of the melt itself and the process atmosphere can provide).

Abstract: Polymer concretes are used in construction, engineering, electrical and chemical industries. Polymer concrete mixes are characterized by low mobility mixtures, due to their high viscosity. It makes difficult to use them in the production of thin-walled and high-reinforced structures, monolithic floors, application of finishing and protective coatings and repairing of roads. The influence of additives of dibutyl-phthalate, chlorinated paraffin, technical glycerin and engine oil on the mobility of the concrete mix and the physical and mechanical properties of fine-grained concrete, based on polyester resin, was studied. For polymer concretes with different type and quantity of plasticizer the density and bending and compression strength were determined. To improve the workability of the concrete mix and obtain a polymer concrete with a homogeneous structure and high strength, it is recommended to use chlor-paraffin ChP-470A and “Lukoil” engine oil as a plasticizer.

Abstract: The results of a research of a way of receiving a composite sorbent with the use of waste of production and processing of the micaceous quartzites (MQ) and montmorillonite clays (MC) are given in this work. The structure of composite sorbents was caused by aspiration as much as possible, to use positive properties of all components entering composition: their high sorption, knitting and plasticizing properties. Similar approach to a combination of components gives, as a result, a synergetic effect, allows to receive the highly effective and, at the same time, inexpensive, rather universal materials having high sorption properties. The sorption activity is investigated, the efficiency of natural and composite sorbents is defined, the increase in sorption activity, depending on structure of composition and temperature of preliminary preparation of a sorbent, is proved. Application of the offered composite sorbents will allow to solve in a complex the existing ecological problems: to carry out effective purification of industrial sewage, first of all, machine-building enterprises from ions of heavy metals, and to utilize waste of production and processing of micaceous quartz.

Abstract: The influence of the type and quantity of filler on the physico-mechanical properties of polymeric concrete is studied. Microcalcite MK-100 and aluminosilicate hollow microspheres “Granulight 3500” were used as fillers. The properties of the microspheres are determined. The compositions were selected and properties of polymeric concrete when using microspheres instead of micralcite and part of the aggregate (sand) as filler were determined. To preserve the workability of the concrete mixture it is recommended to use chloroparaffin CP-470A as a plasticizer. The optimal composition of polymer concrete with the required workability of the mixture and strength is proposed.

Abstract: This paper is devoted to research of utilization possibility of tailings of quartzite enrichment. It is shown that quartzitic waste of JSC "Dinur" (Pervouralsk city, Russia) is suitable for obtaining the cement flooring composite material. It was found that the quartzitic waste can be recommended as a fine aggregate and/or filler after additional screening. With the introduction of quartzitic dust in the amount of 30 % by weight of cement and with quartzitic waste as a fine aggregate it is possible to obtain the composite material of the class not less B12.5 (compressive) and В_tb 5.2 (flexural), which also meet the requirements of the Russian standard, namely abradability, adhesion strength, etc.

Abstract: Iron-based alloys (steel and cast iron) are currently the main structural materials that provide a high level of mechanical and technological properties along with a relatively low cost. Increasing the performance characteristics (tensile strength, hardness, wear resistance, corrosion resistance and, ultimately, service life) of cast irons and steels is an urgent task. The quality of castings made of cast iron and steel depends on many technological parameters that affect the processes of crystallization of the melt (casting temperature, molding mixture, chemical composition, volume of casting, overheating of the metal during smelting, etc.). It is possible to improve the quality of castings without changing the technology of smelting and pouring metal into molds, if you learn how to manage the crystallization process. The laboratories have grown defect – free iron crystals with a tensile strength of more than 1000 kg/m2 (strength of carbon steel-40 kg/m2). Attempts to improve the mechanical properties by creating a single crystal are not justified, so you have to go the opposite way-to influence the crystallization process to get a lot of small crystals (grains), which also allows you to achieve high mechanical properties. The dependence of the strength characteristics on the grain size is well described by the law of Hall-Petch, according to which when the average grain size is reduced by 3...5 times there is an increase in the hardness of the material, with a further decrease in the average grain size by more than 10 times – an increase in plasticity. Influence on the processes of crystallization of iron and steel melts (change the size of metal grains, change the shape, size and distribution of graphite inclusions) can be the introduction of small additives substances (modifiers), not chemically interacting with the matrix. The use of modifiers to increase the rate of crystallization, reduce the structural heterogeneity of castings has good prospects. In addition, unlike doping, modification does not require a large number of expensive additives and, accordingly, slightly increases the final cost of production.

Abstract: A multi-level optimization of size-consist of foam concrete is considered with the aim of significantly increasing its construction and mechanical properties. The results of theoretical and experimental studies confirming the expediency of using this process technology are given. In the course of the studies, theoretical and experimental conditions for creating balanced size-consist of non-autoclaved modified foam concrete with an increased solids concentration per volume unit and performance properties with complex organo-mineral admixture of sustained action on the basis of balanced ratio of chemical and finely-dispersed mineral ingredients optimizing its size-consist and structure were developed. The use of microsilicasuspension in foam composition is theoretically justified, and in the composition of foam-concrete mix of finely-dispersed slag and complex chemical modifier with an accelerating agent, that provide an increase in the strength of non-autoclaved foam concrete by more than 2 times, a decrease in thermal conductivity by 25%, shrinkage – by more than 4 times.

Abstract: The degradation of creep resistance in Nickel-based single crystal superalloys is essentially ascribed to their microstructure evolution. Yet there is a lack of work that manages to simulate the effect of alloying element concentrations on microstructure degradation. In this research, a computational model is developed to connect the rafting kinetics of Ni superalloys with their chemical composition, by combining thermodynamics calculation and an energy-based microstructure model. The isotropic coarsening rate and γ/γ misfit stresses have been selected as composition related parameter, and the effect of service temperature, time and applied stress are also taken into consideration to simulate the evolutions of microstructure parameters during creep process. The different generations of commercial Ni superalloys are selected and their chemical compositions are calculated based on this model. The simulated microstructure parameters are validated by the results from experimental results and the existing analytical model. The capability of the model in predicting the microstructure characteristics may provide instructional thought in developing a novel computational guided design approach in Ni superalloys.