Том 48, № 9 (2018)

Engineering principles are outlined for the production of silicon–aluminum–manganese alloy from high-silica manganese ore and high-ash Kazakhstan coal (from the Borly and Saryadyr fields in the Karaganda and Teniz-Korzhunkol coal basins), Tekturmas quartzite, and Shubarkol long-flame coal. By thermodynamic diagram analysis of the four-component Fe–Si–Al–Mn system on the basis of handbook data (and calculated thermodynamic data where no handbook data are available), a mathematical model of the phase structure may be developed. The aluminum–silicon–manganese composition obtained from the Karaganda and Teniz-Korzhunkol coal, in contrast to the aluminum–silicon–manganese alloy from Ekibastuz coal, is shifted on the thermodynamic diagrams toward tetrahedra with relatively large volume. This indicates increased stability and technological predictability. The results of tests in an ore furnace show that aluminum–silicon–manganese alloy of regular composition may be obtained by a continuous slag-free method from high-ash Borly and Saryadyr coal and unconditioned high-silica manganese ore from the Western Kamys field if Shubarkol long-flame coal and Tekturmas quartzite are added to the batch. The alloy composition may be regulated by adding manganese ore to the weighed batch materials. An alloy with the following composition is obtained: 32–53 wt % Si, 15.5–25.0 wt % Al, 12–32 wt % Mn, 8–20 wt % Fe, 0.02–0.05 wt % P, and 0.2–0.5 wt % C. The resulting alloy does not crumble to powder on storage, thanks to the low phosphorus content and high aluminum content (>10%). The phase components of the experimental alloy are determined. The cost of the alloy is low, since it is produced from high-ash tailings coal and unconditioned high-silica manganese ore, with absolutely no coke. The alloy may be used for the reduction and alloying of steel and also as a reducing agent in the production of refined ferromanganese.

At Abishev Chemical and Metallurgical Institute, highly effective new alloys have been developed on the basis of resource-saving technology. The alloys may be produced from natural and industrial materials such as coal waste and chromium-ore fines. The result is a single-stage, slag-free, and waste-free technology with the maximum utilization of all the useful batch components. As reserves of rich ores are exhausted, alternatives must be sought. The use of leaner and unconditioned ores calls for new processing methods. Such technologies must make the best possible use of the raw materials and production wastes, within the limits of economic feasibility. In many cases, this complex problem is associated with the development of complex processing methods capable of utilizing all the useful components in the raw materials within a single production cycle. In the present work, the goal is to find means of more efficiently utilizing unconditioned chromium ore. In the electrosmelting of aluminum–chromium–silicon alloy, the traditional reducing agent is coke, which is expensive. Our proposal is to use inexpensive high-ash Borly coal. The ash in this coal consists mainly of silica and aluminum and provides an additional source of silicon and aluminum for the alloy. The proposed technology is simple and makes effective use of unconditioned chromium ore, which provides not only chromium but also the silicon and aluminum present in the ash. By complete reduction of all the oxides in the batch, this technology yields aluminum–chromium–silicon alloy with the following approximate composition: 39–43% Cr, 23–27% Si, and 7–10% Al. The extraction of the basic batch components in the alloy is as follows: 82–85% Cr, 68–70% Si, and 59–60% Al. Experimental data are presented for the production of aluminum–chromium–silicon alloy from high-ash Borly coal and chromium-ore fines from Don enrichment facility. Furnace operation is described in the case of deficient, excess, and correct quantities of reducing agent. Methods of eliminating furnace disruption are outlined.

In the analysis of complex industrial processes, it is of great importance to select the most significant factors. Factors are usually ranked on the basis of the researchers’ experience or expert opinions in the field, with mathematical appraisal of their consistency. However, that approach cannot be used in the development of a new process. In that case, experimental methods are used to select the most significant factors. However, this approach is expensive, time-consuming, and sometimes not even feasible. In the present work, a different approach is outlined. Thermodynamic modeling permits numerical experiments. By means of mathematical experiment planning, the influence of more than ten factors on the target function may be taken into account in a single calculation. The particular formulas for the process parameters obtained by this means permit the elimination of the least significant factors without the need for physical experiments. Another important benefit is that this approach permits assessment of the variation in phase and elemental composition of the products and the threshold of practicality of the process in terms of the batch and temperature conditions, with monitoring of the reliability of the results by mathematical means. On that basis, a generalized equation for the monitored process parameter as a function of all the relevant factors may be derived. That is not possible in standard modeling. As an illustration, the proposed approach is used in the development of a production technology for ferroboron using local material. In this case, thermodynamic modeling employs factors selected on the basis of prior calculations. These factors are also used in physical modeling of the process in a high-temperature furnace. The physical experiment confirms the significance of the factors selected. By experiment planning, the number of numerical experiments may be decreased by a factor of 25, and the number of physical experiments by a factor of 125, without loss of predictive accuracy. In the proposed approach, the extraction coefficient may be brought closer to the equilibrium value on the basis of the most significant factors, by comparison of the calculation results with the results of the physical experiments..

The metallurgical properties of PAO NLMK sinter are analyzed. Sinter samples are subjected to mineralogical and microstructural analysis. The microstructural data provide the basis for promising approaches to improving the drum yield and metallurgical properties of the sinter.

A method is proposed for setting upper and lower bounds on the power required in plastic deformation, taking account of the plastic dilation of metallic powder materials (typical dilating materials such as steel or nonferrous alloys). For the upper bound, the basic relations of plasticity theory for rigid–plastic isotropic dilating materials are employed. A functional corresponding to the upper bound on the power required in the plastic deformation of a dilating material within a volume with a finite number of discontinuity surfaces (assumed constant) is derived. For the lower bound, a statically permissible approximate stress distribution is specified, and the lower bound on the power of the surface forces at particular speeds is determined. On the basis of the plastic potential, solutions are constructed for the upper and lower bounds of the plastic-deformation power. As an example, the steady plastic flow when strip is forced through a plane matrix is calculated. On the basis of the results, a system of equations is derived for the limits of the plastic zones, the stress, and the lower bounds on the force and power required in plastic deformation.

The boundary problem for the drawing of a round nonhollow profile in conical die is solved on the basis of the Amontons–Coulomb friction law for preliminarily strengthened metals, whose strengthening is described by the formula σ_s/σ_s0 = 1 + mεⁿ. Taking account of the initial strain, the influence of the parameters m and n of the strengthening curve on the axial stress σ_x in the narrow section of the drawplate and the distribution of the normal stress over the contact surface may be established. On the basis of the solutions obtained, the form of the strengthening curve may be taken into account in calculating the reduction conditions for the multipass drawing of wire and rod. The proposed solutions are compared with existing solutions.

The use of pure iron in UHF radio-absorbing composite fillers is appraised. A method is proposed for selecting iron-based alloys with improved properties. Experiments confirm that the Fe–Al system with 10–14% Al is the most promising filler for such systems. The main trends in the use of such alloys as broadband fillers for radio-absorbing composites are noted.