The study considers ways to increase the efficiency of reduction of iron oxides from man-made waste (dust from electric arc furnaces) using mechanochemical activation (MCA), grinding and pressing. The analysis of chemical and phase compositions of the dust samples was carried out, which made it possible to identify their potential for processing. The experiments included a study of the effect of grinding and pressing at pressures up to 300 MPa on the materials’ phase composition, as well as an assessment of the effects of coke addition during MCA. To study the effect of pressing pressure on the reduction processes, briquettes were fired at a temperature of 1200 °C. The results showed that the degree of iron metallization increases with an increase in pressing pressure: concentration of metallic iron reaches 19 % at a pressure of 300 MPa, which is higher compared to 17 % in the initial state without pressing. The novelty of the work lies in optimizing the pressing parameters and demonstrating its effect on the iron reduction process. The proposed conditions make it possible to increase the efficiency of processing man-made waste, which can be used to improve the environmental and economic components of production.

The Bakal deposit located in the Southern Urals near the city of Bakal, Chelyabinsk region, is one of the largest deposits of carbonate iron ores (siderites). The total deposit of siderites is about 1 billion tons. They are not in demand among metallurgists because of their low iron content and high magnesium content. At the same time, the Urals metallurgical enterprises are suffering from shortage of iron ore raw materials including steelmaking ore raw materials. The high purity of siderites in terms of phosphorus and non-ferrous metals makes it possible to use methods of coke-free metallurgy for their processing. Pyrometallurgical processing of siderites including their reduction roasting in a rotary furnace followed by grinding and magnetic separation allows obtaining a concentrate to be used as a steelmaking raw material having metallization degree above 90 % and a waste rock content under 3 – 7 %. Calculations showed that the costs of electricity used for melting scrap metal and metallized siderite concentrate containing 30 % of waste rock and loaded into the furnace at temperatures above 1000 °C are close. We propose a siderite processing method including reduction of the initial ore in a rotary furnace, and melting of resulting metallized concentrate hot loaded (at temperatures above 1000 °C) into a furnace. The empty rock of metallized siderite concentrate contains a large percentage of magnesium oxide that makes it refractory. To obtain liquid slag, it is proposed to add boric anhydride in the form of colemanite. To assess the B2O3 effect on melting of the metallized siderite oxide phase in the process of electric melting, studies on the viscosity correlation of the magnesian steelmaking slag containing B2O3 with temperature and its composition were carried out. It was found that at the discharge temperature (1600 °C) the resulting magnesia slag with the ratio of MgO/SiO2 in the initial siderite equaling to 0.75 – 1.25 has a low viscosity (less than 3.65 P).

A method for controlling dynamic current-voltage characteristics in an electric arc furnace is described. The influence of the electrode’s current direct component on the accuracy of estimating the resistance of the furnace zones and the direct components of the arc current and voltage is noted. An improved algorithm for determining these parameters is presented with the results of its testing in a laboratory experiment on the use of a metallized additive to a charge for steel smelting. Not only was the addition of scale shown to have no negative effect on the process, it resulted in a slight decrease in the magnitude of the arc direct component, as well as contributing to the slag foaming process.

Ferrous metallurgy enterprises continuously fill dumps with steelmaking and blast furnace sludge with high zinc content. Sludge occupying significant territories of enterprises is not involved in production and harms the environment. Since zinc leads to the formation of deposits in the blast furnace, manufacturers cannot involve this sludge in sinter processing. In addition, working with sludge can lead to problems such as decrease in iron content in the sinter, decrease in productivity of sintering machines, and increase in fluctuations in the sinter chemical composition. At the same time, zinc-containing sludge can become a valuable secondary product. Zinc remains a scarce metal, which encourages the development of technologies for processing zinc-containing materials. Extraction of zinc from sludge is difficult because it is not in oxide, but in sulfate or sulfide forms. In this paper, the possibilities of zinc extraction from sludge using the FactSage software package are evaluated. The authors present results of thermodynamic calculations of the possibility of zinc extraction from four types of sludge from two Russian ferrous metallurgical plants – EVRAZ NTMK and MECHEL. The data of chemical and phase analyses of this sludge are considered, as well as simulated graphs of zinc extraction dependencies from them. The graphs were built on basis of the received data from FactSage package. Addition of the reducing agent to the sludge varied, as well as temperature of the process. In addition, the possibility of abandoning carbon as a reducing agent was evaluated. To save the reducing agent, an optimal mixture of the company’s sludge was selected, in which coke consumption can be minimized.

EVRAZ NTMK JSC has significant amount of blast furnace sludges, that accumulated in dumps. Chemical and phase analysis of that sludges was carried out. It has shown significant amount of zinc sulphate, which prevents such sludge utilization in a blast furnace. Moreover, zinc sulphate requires a high temperature unit for recycling by common schemes. The possibility of zinc sulphate conversation into oxidized zinc with simultaneous metallized residue obtaining under the common for Waelz process temperatures was confirmed in laboratory. The obtained during laboratory experiments metallized residue is suitable for using in blast furnace as charge addition. The results of a thermodynamic analysis of the zinc sulphate conversion to oxide and the physicochemical basis for the extraction of such zinc forms are presented. Theoretical calculations and laboratory experiments confirmed that sludges with zinc sulphate could be suitable materials for blast furnace. But, sludges of different processes allow to obtain fired briquettes with different physical properties.

Zinc can be found in oxide and sulfide forms in technogenic formations. Zinc oxide extraction from technogenic formations is widely used in industry. Removing zinc sulfide from technogenic formations is difficult and is currently almost never used. In the present work, the physicochemical features of zinc extraction from sulfide are considered. Process thermodynamic features and possible ways to extract zinc sulfide are shown. Also, ways of valuable commercial products, obtaining from the roasting products, are considered.

The comprehensive methodology for the zinc extraction from sulfide compounds into the oxide form with possible further reduction to metal is presented in this study. It was demonstrated in laboratory conditions during sludge treatment with Zn and ZnO obtaining. The remaining silicate products. It is proposed to recycle this material into Portland cement clinker to ensure a waste-free process. Keywords: zinc sulfide, zinc oxide, sludge recycling, Portland cement clinker, waste-free recycling

Analyse of the blast furnace charge chemical content changing with the JSC EVRAZ NTMK raw materials base alteration was carried out. That expected change would result in TiO2 content increasing in the blast furnace slags. That increasing would lead to carbonitride formation in the upper levels of the blast furnace, which reduce technical parameters of the blast furnace operation by reducing effective volume of the furnace and derange regular charge moving. Possible ways of that problem solving was shown. It was proposed the complex technology, that affect 3 technological stages: agglomeration, blast furnace process and out-of-furnace treatment of steel. Converting of TiO2 into CaO·TiO2 allows to delay carbonitride formation due to increasing required temperature for that process. In that case, carbonitride formation would move to the tuyere zone of blast furnace, where it increase lining durability. The proposed technology was industrially tested, and the main idea was proved. Few problems were found during industrial tests, but theoretical solving of them was proposed.

Ladle furnaces at Evraz Nizhnii Tagil Iron and Steel Works OJSC produce over 90,000 metric tons of slag per year. As this slag cools, it turns into a fine-grained powder; if the powder cannot be sold, it is temporarily stored until it can be disposed of [1]. We have considered producing easily used flux sinter from the slag generated during ladle processing of steel (hereinafter, ladle-furnace slag or LFS). Since LFS still contains a large number of metallic inclusions, it cannot be included in sinter fed into a hammer mill via the enclosed lime feed trough. LFS was therefore added to the iron flux charge along with the steel smelting fluxes in a duplex and mono process (steel converter slag (SCS) and vanadiumbearing converter slag (VCS)); the fluxes are then crushed in a jaw crusher. A successful test of the use of LFS in sinter was performed, the charge was free of raw limestone, coke consumption was lower, sinter machinery production capacity was higher, and the weight/sample ratio of the sintered product was improved. Since SCS and VCS contain up to 3.0% V2O5, this provided an opportunity to increase vanadium use during the blast-furnace sintering process by more than 100 metric tons of vanadium per month.

In technogenic formations, zinc is found in oxide and sulphide forms. Extraction of zinc oxide from technogenic formations is widely used in industry. Removing zinc sulfide from technogenic formations is difficult and is currently almost never used. In the present work, the physicochemical features of zinc extraction from technogenic formations, in which zinc is presented in oxide and sulphide forms, are considered. Thermodynamic features of the processes and possible ways to extract zinc sulphide are shown. This work also considers the ways of valuable commercial products obtaining from the roasting products.

The EAF and LF slag processing became an actual issue at the present day metallurgy. The possibility of joint and complete utilization of both electric furnace and ladle slag is considered in this paper. The purpose of the work was to develop a method for joint processing of EAF and LF slag with the production of marketable products. A simplex-lattice planning method was used during the work. The raw mixture consisted from EAF slag, ladle slag and limestone. The components of the raw mixture were mixed according to the experimental design, heated and melted under reducing conditions. The phase and chemical composition of melting products, obtained during the experiment, were determined. The results of the experiment showed that both slags and lime can be used together to produce Portland clinker and pig iron. These products are in good agreement with normative documents and thus, they can be used in further production.

The article presents the results of a study of formation mechanism of magnesia-ferrite when heated siderites of the Bakal deposit with different iron oxide content in an inert and oxidizing atmosphere. It was established that in the case of firing in an inert atmosphere, the decomposition of siderite with high iron content begins at a lower temperature and the enthalpy of such decomposition is less. This effect can be explained by the different phase composition of the samples. The main phases formed under conditions of oxidative firing are hematite and magnesia-ferrite. The amount of hematite and magnesia-ferrite produced in the samples with different iron oxide content during firing in an oxidizing atmosphere is different. Siderite with high content of iron oxides contains more hematite in the firing products than magnesia-ferrite, and siderite with a low content of iron oxides contains more magnesia-ferrite in the firing products than hematite. Formed under conditions of oxidative firing magnesia-ferrites are solid solutions and differ in the degree of substitution of iron and magnesium ions. In siderites with high content of iron oxides, the degree of substitution of magnesium ions with iron ions is greater than in samples with a low content of iron oxides. Since the siderites of the Bakal deposit are poor ore formations, the considerable amount of magnesia-ferrite formed in them during firing makes it difficult to separate silicate and iron-oxide firing products by traditional enrichment methods. Wustite in the products of oxidative firing is not detected, because under these conditions it is in a metastable state and in the presence of a weakly oxidizing atmosphere is converted into magnetite. The scientific novelty is the explanation of the mechanism of siderite decomposition and the description of products of such decomposition. Understanding of the mechanism of decomposition of siderite from the Bakal deposit made it possible to develop the technology of reductive firing of siderite to facilitate separation of its products, and which consists in the regulation of the phase composition of silicate products of reductive firing, ensuring the collapse of magnesia-ferrite and output of iron oxide in a separate phase. The developed technology can be used to provide high-quality enrichment of siderite from the Bakal deposit.

Methods of ladle furnace slag stabilization are analyzed. It is shown that increasing the Al2O3 content of slag to higher than 18% results in chemical stabilization of slag. It is revealed that if the Al2O3 content is less than 30 wt.%, the refining properties of the slag do not degrade. When that content is exceeded, Al2O3 behaves similarly to SiO2, i.e., reduces the desulfurization ability of slag and makes it more corrosion aggressive. The most favorable content of Al2O3 in slag is from 12 to 25%, the properties of slag varying from basic to acidic. If the Al2O3 content is higher than 14%, the probability of formation of MgO–Al2O3 refractory spinel on the surface of refractory products increases, thereby increasing the durability of ladles and vacuum chambers.

Nowadays due to the application expansion of secondary steel processing methods, which provide high-degree metal desulfurization, a problem of the ladle furnace slag (or high-calcium refining slag) stabilization arose in the ferrous metallurgy. This slag cannot be stabilized because of its self-disintegrating properties.

Nowadays almost all smelted steel is processed in "ladle-furnace" (LF), where the steel is processed under refining conditions and brought to the desired temperature and chemical composition. Therefore, large amounts of refining slag are formed. Only in Russia there is about 1.4 million tons of slag exported to dumps annually. This slag cannot be processed by the schemes implemented in the industry, since the slag quickly turns into the tiniest dust during solidification and cooling. Such dust is easily aerated and carried by the wind for long distances; it pollutes soils, dissolves in ground, sedimentary and sewage waters. It also pollutes slag dumps that are suitable for processing for crushed stone.

There are two main kinds of slag in modern steelmaking industry: the electric arc furnace slag ( EAF slag) and ladle furnace slag (LF slag). The all known slag processing schemes provide the iron-containing component reduction while silicate component stays unprocessed. On the contrary, the silicate processing schemes doesn't provide the utilization of the iron-containing component. The present-day situation doesn't solve the problem of total slag utilization. The aim of this work is to investigate the opportunity of silicate product obtaining with simultaneous pig iron reduction from EAF and LF slags. The tests are conducted by the method of simplex-lattice design. The test samples are heated and melted under reductive conditions, slowly cooled and then analyzed by XRD methods. The experiment results prove the opportunity: the Portland clinker and pig iron can be simultaneously produced on the basis of these slags with a limestone addition.