THEORY AND TECHNOLOGY OF MANUFACTURING A FERROALLOY FROM CARBON FERROCHROME DUSTS

The article contains the research results of obtaining a ferroalloy from a carbon ferrochrome dust containing 30,2% of Сr2O3, 23.4% of SiO2, 32.7% of MgO, 5.0% of FeO, 1.6% of CaO, 4.5%of Al2O3, 2.3%of C, and 0.3 %-others. The studies were carried out by a thermodynamic modeling method using the HSC-5.1 software package (Outokumpy) based on the principle of the Gibbs energy minimum, the Box-Hunter rototable planning technique and electric melting of the dust in an arc furnace. It was found that the interaction of the dust with carbon under equilibrium conditions and in the presence of iron leads to formation of Cr4C(T>10000C),Cr3C2, Cr7C3,Cr (T>11000C), FeSi (T>13000C), SiC (T>14000C), SiOg and Si(T>15000C). In the temperature range of 1745-19000C and in the presence of 18-34% of carbon and 8% of iron of the dust mass, the resulting ferroalloy contained 18.5-25.2% of Si and 46.8-49.4% of Cr (in this case the silicon extraction degree into the alloy was 60.0-64.4%, the chromium one–99.8%). When the electrosmelting the granulated dust together with coke and steel shavings, the chromium extraction degree into the alloy was 98-99%, the silicon one–53-57%; the obtained ferroalloys containing 18.3-21.9% of silicon and 45.6-53.6%of chromium meet the requirements to FeCrSi23-grade ferrosilicochromium.

Analysis of Impact of New Technologies in Metallurgy on the Industry Production Function and Total Factor Productivity

Identification of positive conditions for structural transformation of industries in the Russian economy and also formation of a scientific base for development of practical recommendations for industrial policy are extremely important for the fulfillment of national goals set forth in the Presidential Decree No. 204 dated May 7, 2018. From the early 2000s up till now, development of the Russian metal industry has been characterized by gradual abandonment of the traditional method of steelmaking in open-hearth furnaces as well as transition to a more progressive electric melting technology. The article assesses the impact of this technology change on total factor productivity (TFP) of metallurgical enterprises and on the functional form of the production function in the industry for the period 2008–2017, as well as the factors of transition to the new technology for metallurgical companies. The results show that the transition to the new technology was accompanied by a 24–28% increase in TFP as well as changes in the parameters of the production function, in particular, a decrease in labor and material intensity of production. An analysis of the factors influencing the likelihood of transition to the new technology has confirmed our hypotheses: the process of assets consolidation in the metallurgical industry under the control of several holdings in the 2000s was accompanied by technological re-equipment of production and construction of new facilities. Enterprises that are part of a single financial and industrial group with higher productivity and access to the world market are characterized by a higher probability of transition to the new technology. In addition, estimates of the likelihood of transition to the new technology are higher for enterprises with higher levels of productivity.

Study of the High-temperature Synthesis of MgAl2O4 Spinel Refractory Raw Materials from Chromium Slag

To make use of chromium slag waste, this study examined the technology of the preparation of MgAl2O4 spinel refractory raw material by using chromium slag. The results showed that (1) using the traditional sintering process of synthetic spinel, the highest volume density was 3.14 g/cm3 and the lowest porosity rate was 9.16 %. With the increase of the proportion of MgO powder mixing, bulk density and porosity fluctuations, and which cannot meet the requirements of refractory raw materials. (2) For MgAl2O4 spinel prepared by the electric-melting process, the highest volume density was 3.27 g/cm3 and the lowest porosity rate was 8.78 %. Volume density and the porosity remained stable, and they are affected by MgO powder thus the blending ratio is very small, which can satisfy the requirements of refractory raw materials. (3) MgAl2O4 spinel prepared by the electric-melting method is superior to traditional MgAl2O4 spinel in terms of slag resistance and thermal shock resistance.

Mechanical Characteristics of Nuclear Main Steam Line Penetration Fabricated by Electric Melting Additive Manufacturing

Additive Manufacturing (AM) can fabricate 3D near-net-shaped functional parts using unit materials, such as powder or wire. Additive manufacturing’s computer-aided design offers superior geometrical flexibility. The near-net shaping capability also reduces materials waste and increase manufacturing efficiency significantly. These benefits make AM desirable for critical industry applications, such as art, aerospace, ground transportation, and medical. Confident utilization of the technology requires thorough understanding of the AM materials, ensuring both structural integrity and performance requirements are met or exceeded. Safety and economics are essential to nuclear power plant. In this study, mechanical properties of a ferritic steel fabricated by electric melting additive manufacturing (EMAM) technique are studied and compared with ASME SA-336 Gr.F12, which applied to nuclear main steam line penetration, the results are systematically presented and discussed. Key technical issues of application of AM to manufacturing nuclear components are also discussed.

The Reduction Processes of the Titanium Containing Iron Ores Treatment

The questions of metallurgical processing of titanium-containing ores are considered. The ores and concentrates of the Kachkanarsky deposit of low-titanous and high-titanous are studied. The reducibility, durability, temperatures of a softening and melting of metallurgical iron ore raw materials are studied in vitro. Via X-ray the structural analysis are carried out. The calculations by means of mathematical models of pyrometallurgical processes are executed. Possibility of the processing of these ores according to schemes is shown: «blast furnace melting − converter melting» and «metallization – electric melting».