Manufacturing and Application of Complex Ferroalloys

The tightening of requirements for the quality of steel, a change in the composition of raw materials requires the release of more efficient ferroalloys of the new generation, suitable for progressive steel production processes. Such products include complex ferroalloys containing, in addition to iron, two or more functional elements. Complex ferroalloys should be created in the most favorable combination of components, contributing to the necessary effective impact on the quality of the metal being processed, with a high degree of assimilation of useful elements in it. Changes in the characteristics of complex ferroalloy, affecting the assimilation of target (basic) elements, should be carried out by regulating the composition and ratio of elements that can be included in almost any ferroalloy, since they are part of all steels and cast irons or they’re required by the conditions of their smelting. Firstly, these elements should include silicon and manganese. Silicon can reduce the melting temperature, density, and melting time of ferroalloy in the liquid metal. For example, the addition of 1% silicon to low-carbon ferrochrome can reduce the melting point of the alloy by 8–9 degrees. Compositions of new complex ferroalloys of systems Fe-Si-Ca-Ba, Fe-Si-B, Fe-Si-Al-Nb, Fe-Si-Mn-V have been successfully tested and introduced into production. Keywords: metallurgy, ferroalloy, melting, density, physical and chemical properties, stee

Promising Directions of the Application for Poor Raw Materials of the Ferroalloy Production

The mineral base state for Russian manganese and chromium ores does not allow our country in the foreseeable future to achieve complete self-sufficiency and to abandon imported raw materials. But the problem can be significantly mitigated due to the partial involvement in the operation of the proven ore reserves with relatively low quality. Based on the performed research, four main directions are formulated that would make it possible to put into operation a number of previously known but out-of-use (or poorly used) deposits of poor mineral raw materials for the ferroalloy production: (1) selective reduction of ore components divided into metal semi-products with a low main component content suitable for the smelting of the alloyed steel grades and an oxide product with a high content of Mn or Cr oxides suitable for the smelting of the high-grade ferroalloy grades; (2) rational additional charging of poor domestic ores to beneficiate imported ones to obtain standard grades of ferroalloys; (3) smelting of new alloys, including marketable high-carbon ferromanganese and ferrochrome with reduced main component content, high silicon content, and complex ferroalloys containing, in addition to the main, other elements necessary for the composition of a number of steel grades (silicon, manganese, titanium, etc.); and (4) production of limited grades of ferro-, silico-manganese, and chromium and their application in smelting of the ferroalloys refined grades. Keywords: metallurgy, ferroalloys, mineral resource base, poor ore

Promising Measures to Reduce the Harmful Effects of Man-made Waste from Ferroalloy Production

This article formulates a list of promising measures to reduce the harmful impact of man-made waste from ferroalloy enterprises on the environment: (1) technical measures: replacement of the main and auxiliary obsolete equipment with new environmentally safe, allowing to significantly reduce or completely eliminate hazardous emissions and the formation of unclaimed production waste; (2) introduction of energy-saving technologies: the use of physical and chemical energy of top gas from ore-reduction furnaces in turbine generators and in the contrivance for preheating and partial reduction of charge materials elements, etc.; (3) prevention and localization of emissions due to the modernization of existing equipment: sealing and shelter of the main melting equipment, places of loading and unloading of bulk materials, prevention of dusting for the ore materials warehouses, tailing ponds, sludge collectors, etc.; (4) cleaning of harmful emissions, the formation of which cannot be prevented; (5) introduction of innovative waste-free and low-waste technologies with the integrated use of raw materials: utilization of accumulated and current waste (slags, sludge, etc.) that form during the production of ferroalloys, reducing or completely eliminating the waste dumps and sludge collectors; (5) deeper ore preparation with the exception of the use of toxic reagents; and (6) more complete and economical use of water, the creation of closed water systems, the use of modern highly efficient treatment facilities, etc. Keywords: metallurgy, ferroalloys, man–made wastes, slag, sludg

Stabilization of Self-slaking Slags from Ferroalloy Production

In this study, the process of stabilization for highly basic self-slaking slags of ferroalloy production by various boron-containing materials were studied: tincalconite, colemanite, and ulexite (produced in Turkey). The viscosities and temperatures of crystallization for the initial boron-containing materials are determined. Under laboratory conditions, high-base slag melts were treated with boron-containing materials to obtain slags containing 0.25 and 0.5% B2О3. It was shown that the addition of boric anhydride to the studied slag melts extends the homogeneous-liquid state interval and reduces their viscosity by 1.2–1.6 times, therefore B2О3can be used as a tool for controlling slag mobility in industrial conditions. The industrial tests were conducted to stabilize the slag of low-carbon ferrochrome using powdered calcined, briquetted, and fused colemanite. After treatment, slags contained 43–47% CaO, 0.18–0.45% B2О3. The results of pilot-industrial experiments show that all applied boron-containing materials ensure slag stabilization and differ only in the degree of boron recovery. Fused colemanite showed the highest results in the recovery of B2О3(up to 98%), a commercial product was obtained which fully complies according to the technical characteristics with the requirements of Specification TU 0798-69-00186499-2014 “Crushed stone and sand from ferroalloy slags. Technical conditions.” Keywords: ferroalloy, slag, self-slaking slag, stabilization, boron, two-calcium silicat

Simulation of the Melting Process for Complex Nickel-containing Ferroalloys in Steel

In this study, the melting process simulation for the complex nickel-, silicon-containing ferroalloys in a steel melt was performed. For the study, complex ferroalloys samples (∼ 10% Ni, 5–56% Si) were selected, by composition corresponding to the alloys, which can be smelted from poor Russian oxidized nickel ores. It is shown that all the alloys under consideration belong to the group of low-melting ferroalloys, in which the liquidus temperature (

The Thermodynamic Evaluation of the Interphase Distribution of Elements in the Chromium and Nickel-containing System

The results of thermodynamic modeling of the process of element reducing from a chrome-containing ore-lime melt by silicon ferronickel depending on temperature are presented in this article. The consumption of reducing agent is equal to 105% of the required stoichiometric amount of reducing agent for complete reduction of iron and chromium in the temperature range of 1300–2200∘С. The chemical composition of the ore-lime melt is, wt. %: 24 Cr2O3; 13 FeO; 42 CaO; 3 SiO2; 9 MgO; 9 Al2O3 and of silicon ferronickel is, wt. %: 65 Si; 28 Fe; 7 Ni. The HSC Chemistry 6.12 software package developed by Outokumpu Research Oy (Finland) is used. The composition of oxide Cr2O3-FeO-CaO-SiO2-MgO-Al2O3 and metallic Fe-Si-Ni-Cr systems are calculated using the module «Equilibrium Compositions». A gas phase pressure is 1 atm. The gas phase of the system contains 2,24 m3 N2. It is established that the increase in the process temperature from 1300 to 2200∘С contributes to reducing of the degree of chromium reduction from 98,9 to 69,8%. The degree of reduction of aluminum and magnesium increases from 0,2 to 8,7% and from 0,007 to 2,5% respectively, and the degree of reduction of iron doesn’t change over the entire temperature range and is equal to 100%. The chromium content in the metallic phase decreases with increasing temperature from 51,7 to 41% and the residual CrO content in the slag increases. The chemical composition of the alloy is, wt. %: 50,41 Cr; 44,06 Fe; 1,97 Si; 3,3 Ni; 0,035 Mg; 0,21 Al; 0,005 P at the temperature of 1700∘С. The results of thermodynamic modeling can be used for laboratory experiments and technological calculations for obtaining chromium and nickel-containing complex ferroalloys suitable for smelting stainless steel grades. Keywords: thermodynamics, system, interphase distribution, reducing agent consumption, degree of recovery, temperature, chromium, nicke

Development of the New Method for Oxidized Nickel Ore Processing

In modern conditions of sharp fluctuations in nickel prices on world markets, the problem of profitability of processing Russian poor oxidized nickel ores (ONO) has arisen. As an alternative to the previously existing in Russia, a sulphidation-reducing smelting on a matte, a hydro-pyrometallurgical method has been proposed for the preparation of complex nickel-, chromium-, manganese-containing ferroalloys. At the first stage, hydrolytic precipitation (with sodium hydroxide) is considered as a method of processing production solutions from heap leaching of ONO. It is established that at pH = 5.5, Al is completely removed in the precipitate as hydroxide. After washing from impurities and calcining, a concentrate containing 50 wt.% Al was obtained. At the second stage, at pH = 9.5, more than 99% of nickel and cobalt oxides, as well as 92% oxide concentrate contains, by weight. %: 67 NiO; 3 CoO; 20 MnO; 9 MgO; 0,2 S. At the third stage, a pyrometallurgical method for smelting complex ferroalloys of the Fe-Ni-Cr- Mn-Si system using refractory ferrosilicochrome as a reducing agent is proposed for the processing of nickel-containing concentrate. The scheme of hydro pyrometallurgical method of ONO processing includes: crushing, heap leaching, hydrolytic precipitation to obtain an aluminum-cobalt and nickel concentrates, silicothermic smelting to obtain complex nickel, chromium, manganese ferroalloys, for smelting of suitable stainless steels. Keywords: oxidized nickel ores, nickel, cobalt, manganese, leaching, precipitation, roasting, metallotherm

Melting of high-carbon ferrochrome using coal of the saryadyr deposit

The article presents the results of large-scale laboratory tests on the smelting of high-carbon ferrochrome with the replacement of parts metallurgical coke with high-ash coal from the Saryadyr deposits. According to the test results, it can be stated that the optimal percentage of replacing metallurgical coke with high-ash Saradyr coal is 30 – 40 %. During a large-scale laboratory test, it was also established that the cost of the alloy was reduced due to the partial replacement of expensive coke and removes the fluxing component of quartzite from the charge composition, and improves the TPE of the high-carbon ferrochrome smelting process

Thermodynamic diagram analysis (TDA) of MnO–CaO-Аl2O3-SiO2 and phase composition of slag in refined ferromanganese production

The research presents the calculations of the analytical expressions of the oxide system MnO-CaO-Al2O3-SiO2 and the phase compositions of the slags from the production of refined ferromanganese. It is determined that the system under consideration is divided into 19 elementary quasi-systems consisting of incongruently melting and congruently melting compounds. The sum of the relative volumes of the elementary tetrahedron of the MnO-CaOAl2O3-SiO2 system equals one (1,000000), which confirms the accuracy of the performed calculations. Quasi-volumes in the system MnO-CaO-Al2O3-SiO2, simulating the composition of the resulting slag in the process of metallothermic recovery of manganese concentrates are found