Slag Formation Research Articles

ИССЛЕДОВАНИЕ МЕХАНИЗМА ШЛАКОНАКОПЛЕНИЯ В КОНТУРАХ СО СВИНЕЦСОДЕРЖАЩИМИ ТЕПЛОНОСИТЕЛЯМИ И ЕГО ПРЕДОТВРАЩЕНИЕ ВЫСОКОТЕМПЕРАТУРНОЙ ОБРАБОТКОЙ СМЕСЯМИ ВОДОРОДА И ВОДЯНОГО ПАРА

The results of computational and experimental studies of the properties of lead and lead-bismuth coolants and the mechanism of physicochemical processes occurring in their circulation circuits explain the reasons for the formation of slag deposits based on lead oxide. First of all, this is the uncontrolled interaction of lead and lead-bismuth coolants with gaseous oxygen, which, along with nitrogen, is one of the main components of air. Slag deposits are based on lead oxides, but they also contain a significant amount of unoxidized lead (and bismuth in the case of using a lead-bismuth coolant) bound by a lead oxide framework into a single structure, as well as a small amount of components of construction materials (iron , chrome, nickel). The formation of slags in the circulation loop with a lead-containing coolant has a negative effect on its operation: the flow cross-sections are narrowed; heat transfer surfaces are blocked; the normal operation of pipeline fittings is disrupted. To minimize slag accumulation, it is necessary to limit the contact of the coolant with air oxygen, avoid draining the coolant from the circulation circuit, control whether the circulation circuit is in a depressurized state both during research and during non-working periods, when heating and filling the circuits with a coolant, create and maintain a vacuum. The best way to prevent slag accumulation is periodic hydrogen cleaning of the circuit with gas mixtures "hydrogen - water vapor - inert gas". The greatest cleaning efficiency is achieved when gas mixtures are introduced directly into the coolant flow using gas injection devices. Mechanical devices with moving parts, ejectors, nozzle nozzles can act as gas injection devices.

Interactions between Automotive Shredder Residue and Olivine Bed Material during Indirect Fluidized Bed Gasification

Thermal conversion of automotive shredder residue (ASR) using indirect fluidized bed gasification was conducted in the Chalmers semi-industrial 2–4-MWth gasifier. The bed material consisted of olivine that was activated through the deposition of biomass ash prior to a 13-day exposure to ASR. The interactions between the bed material and the ASR ash were investigated using XRD, SEM-EDS, and thermodynamic modeling. The deposition of iron (Fe) onto the olivine particles was noted, and this is likely to increase the oxygen-carrying ability of the particles. Furthermore, at the end of the campaign, about one-third of the particles in the bed were found to originate from the ASR ash. These particles were rich in Fe and Si, as well as elements found exclusively in the ASR ash, such as Zn, Ti, and Cu. Some of these particles exhibited a hollow morphology, suggesting a melt state during their formation in the gasifier. In addition, a low level of agglomeration of the ash and olivine particles was detected. Thermodynamic modeling with the FactSage software indicated the formation of slag. This study presents a detailed investigation of the interactions that occur between the bed material and an ash-rich fuel such as ASR. The findings may have applications in demonstrating the induction of oxygen-carrying ability in bed materials or for metal recycling through the separation of ash particles from the bed material.

Investigations of regularities in the accumulation of hydrogen-reduced slags in circulation circuits with lead-containing coolants

The paper presents a computational analysis of regularities in the accumulation of slags during the interaction of lead and lead-bismuth coolants with oxygen gas. Oxidation of lead-containing coolants will cause the formation of lead oxide, while the formation of bismuth oxide is unlikely. Dosed supply of oxidizing gas to lead-containing coolants makes it possible to oxidize, selectively, chromium and nickel to their oxides without the slag formation from solid lead oxide. Regularities were studied which are involved in the lead oxide formation during the interaction of lead-containing coolants with oxygen gas. It has been found that, in the process of interacting with oxygen gas, a lead-bismuth alloy is oxidized 1.7 times as intensively as lead, this being explained by the presence of bismuth in the alloy. Bismuth is oxidized more intensively than both lead and the lead-bismuth alloy. The inert gas overpressure during depressurization does not prevent air oxygen from entering the circuit, and the dependence of the nitrogen and oxygen flow into the circuit on the argon flow out of the loop is close to linear regardless of the circuit state (cold, without coolant; heated, without coolant; heated, with circulating coolant). Oxygen is a chemically active impurity and is absorbed by the circuit; it is therefore important to control nitrogen in the gas spaces of the reactor and research plant circuits with lead-containing coolants. This will make it possible to signal, in a timely manner, the ingress of oxygen into the circuit and to take measures required to avoid or reduce the scale of the slag formation from lead oxides.

Video registration of physicochemical processes in BOF cavity at bath top blowing at application oxygen lances of various designs. Report 2. The picture of bath blowing at application two-circuit lances

To elaborate blowing and slag modes, a clear picture of BOF bath blowing in various periods of heat is needed. It can be obtained by video registration of physicochemical processes in a BOF cavity. Results of video filming of BOF bath blowing with application two-circuit oxygen lances of five designs presented. Reliable information was obtained on rational form of organization of reaction zone of interaction of ultrasonic and sonic oxygen jets with BOF bath. The picture of physicochemical processes within the reaction zone of interaction of oxygen jets with metal, slag and gas phases of the cavity, preceded to a stable “ignition” of a heat and in the process of the whole heat. A possibility was revealed to accelerate the processes of lime dissolving and slag formation and phosphor removal intensification. The intensification can be accomplished by increase of the number of reaction zones of interaction of ultrasonic and sonic oxygen jets on bath surface and forming of foamed slag-metal emulsion, being stable within the basic part of blowing time. It was shown that at initial period of a heat, it is necessary to ensure consolidation of supersonic oxygen jets, coming out of different reaction zones of interaction. It will enable to oncoming jets to create a curtain on the way of metal and slag drops taking away, to form a flare of CO afterburning to CO2 and ensure heat energy transfer from them to mainly the bath surface. It was established that at the location of the foamed slag-metal emulsion level higher the head end of the lance, the high-temperature products of CO to CO2 afterburning reaction transfer the heat of CO surrounding macro bubble to the shell of slag-metal emulsion. An additional control effect of “hard” supersonic oxygen jets on the bath was also established when replacing the subsonic and sonic oxygen jets by nitrogen ones. At that the flow rate of nitrogen should be big enough to prevent the sealing of cylinder nozzles of the lance head by metal and slag drops during final stage of blowing. The variant of the final stage of blowing was checked experimentally by transfer to the “hard” supersonic oxygen blow, contributing to final metal and slag oxidation decrease.

Study on the Refining Conditions of Nickel Pig Iron for High Purity Nickel Matte Production

Nickel has been known to be the most important metallic resource, which has been used in various products, such as multi-layer ceramic capacitors, Li-ion batteries, heat-resistance super alloys. Those Ni resources have various types such as metallic nickel, ferronickel alloy, nickel matte, and nickel sulfate depending on the situation. In a production route of high purity nickel matte from ferronickel, which had been implemented many decades ago, a large amount of by-product, as well as relatively high operational cost, have been recently drawing attention. To resolve arisen problems, nickel pig iron can be suggested as a low-cost raw material. The possibility of upgrading nickel pig iron by removal of Fe and enrichment of Ni was investigated by lab-scale oxidation experiments. It was found that major impurities like C and Si should be removed before Fe oxidation initiates. And decarburization and desiliconization of nickel pig iron were enhanced by oxygen injection, compared with other blowing manners. The slag conditions for effective Fe oxidation were discussed using thermodynamic calculation and oxygen blowing tests. Conclusively, the continuous addition of CaO during oxygen blowing enables the formation of liquid slag and further Fe oxidation. In the case of Fe2O3-SiO2 based slag, liquid slag seems to be limited by MgO dissolution from refractory

Direct microalloying of steel with cerium under slags of СаО–SiO 2 – Ce2O3– 15 % Al2O3 –8 % MgO system with additional reducing agents

An assessment of the possibility of steel direct microalloying with cerium was performed using thermodynamic modeling of cerium reduction from slags of CaO– SiO2– Ce2O3 system containing 15 % Al2O3 and 8 % МgO, additional additives of reducing agents (aluminum or ferrosilicoaluminium), at temperatures of 1550 and 1650 °C using the HSC 6.1 Chemistry (Outokumpu) software package. Depending on the additional additives of aluminum or ferroglycoaluminium, metal temperature, slag basicity and content of cerium oxide, 0.228 to 40.5 ppm of cerium transfers into the metal. With an additional additive of aluminum from slag (Y1) containing 1.0 % of cerium oxide, 0.228 ppm of cerium is transferred to the metal at 1550 °C. An increase in the system temperature to 1650 °C is accompanied by a slight increase in cerium content, reaching no more than 0.323 ppm. When added to ferrosilicoaluminium metal, cerium content in the metal is higher and amounts to 0.402 and 0.566 ppm at 1550 and 1650 °C, respectively. When concentration of cerium oxide in the slag (Y2) increases to 7.0 %, more signifcant increase in cerium content in the metal is observed, reaching in temperature range of 1550 – 1650 °C, 1.65 – 2.31 ppm with aluminum additives and 2.90 – 4.05 ppm with ferrosilicoaluminium additives. The most noticeable increase in cerium content in the metal is observed with an increase in slag basicity. During formation of slags with basicity of 2 – 3, containing 1 – 7 % Ce2O3, the equilibrium concentration of cerium in the metal varies from 0.5 to 4 ppm with aluminum additives and 1 – 7 ppm with ferro­silicoaluminium additives at 1550 °C. Slags transfer to the increased (up to 3 – 5) basicity is accompanied by an increase in the equilibrium content of cerium in the metal to 4 – 12 ppm with aluminum additives and 7 – 20 ppm with ferrosilicoaluminium additives at Ce2O3 content of 3 – 7 % and, as a result, an increase in efciency of cerium reduction process.

Investigation of Correlation Between Fracture Toughness and Charpy Impact Energy of Cryogenic Steel Welds.

The high manganese steel was developed to improve the fracture toughness and safety at cryogenic temperatures, the austenite structure was formed by increasing the manganese (Mn) content. The developed weld high manganese steel was alloyed with austenite stabilizing elements (e.g., C, Mn, and Ni) for cryogenic toughness and fluxes contained less than 10% of acidic slag formers such as rutile (TiO₂) and silica (SiO₂). This paper describes the work carried out to enhance the fracture toughness of Mn contents in an economical way by means of increase of manganese up to 23% instead of using nickel (Ni) which has unique element to improve fracture toughness especially at cryogenic steel. The new cryogenic steels should be carefully evaluated in terms of safety for application in real structures including LNG ships. In this study, the fracture toughness performance was evaluated for recently developed cryogenic steels (high-Mn steels), especially the crack tip opening displacement (CTOD) parameter was evaluated using the prediction formula proposed by conventional equation. The CTOD value was investigated the effect of microstructure and mechanical properties of Fe-C-Mn and Fe-C-Mn-Ni high manganese steel, it was revealed that the e-martesnsite phase formed in high manganese steel of 0.2C-20Mn and 0.4C-20Mn as a result of a low stability of austenite upon strain-induced phase transformation.

Investigation of control methods for agglomeration and slagging during combustion of olive cake in a bubbling fluidized bed combustor

Olive cake is an agricultural residue with a high calorific value and high availability. It should be considered in energy production for use in waste management and the waste-to-energy approach. However, there are some ash-related problems encountered during olive cake combustion with a silica bed due to its high alkali content. In this study, two control methods (silica bed with olive cake leaching, and limestone-bed material) were investigated to prevent ash-related problems. The combustion tests were conducted in a bubbling fluidized bed. Bottom ashes and slags were analyzed to determine elemental composition and phase composition. Agglomeration was detected at 850 °C for olive cake combustion by itself. Removal of the alkalis in the olive cake by leaching prevented silicate formation and produced a noticeable decrease in the rate of silica bed agglomeration and slag formation during combustion of the leached olive cake. Using limestone as the bed material instead of silica sand was even more effective than leaching of olive cake in terms of preventing slagging. The use of limestone as fluidizing bed material causes Ca and Si to form compounds with the high melting point. The positive effect of these control methods on agglomeration and slag formation should make it possible to use olive cake in energy production without any operational problems.

Basic Oxygen Steelmaking Slag: Formation, Reaction, and Energy and Material Recovery

Basic oxygen steelmaking (BOS) slag, a product of hot metal element (e.g., Si, Mn, Fe, P) oxidation and flux (e.g. lime, dolomite) dissolution, plays a critical role in the production of high‐quality crude steel, although its behavior inside the BOS vessel (formation and reaction with metal droplets and gas) is still not clear and its recycling has always been challenging. Herein, examples of BOS‐slag‐related research conducted by the present authors are introduced, in addition to a critical review of relevant research reported in the literature. This includes four important topics: 1) slag formation, i.e., dissolution of lime in the BOS slag; 2) in situ observation of high‐temperature behavior of BOS slags; 3) transient phenomena in BOS slags due to metal droplet–slag–gas reactions; and 4) energy and material recovery from molten BOS slags. This article aims to provide state‐of‐the‐art understanding and new research ideas on these research topics. An emphasis is placed on methods that seek to in situ probe the evolution of the slag and to document its physical and chemical changes.

Effect of particle system on slag formation and shedding characteristics of high alkali metal coal in full-scale circulating fluidized bed boiler based on Nano-CT

In the combustion process of Zhundong coal, many factors had obvious influence on slagging process. In this paper, the influence of particle system on slag formation and shedding process was evaluated. Two slags were sampled at two CFBBs super heaters which temperatures were similar and the ash particles size and concentration were different. The collected slags were separated, and the inner layer was analyzed by XRF, XRD, and Nano-CT. The results suggested that the area ratio of particles smaller than 2 μm to the region area was above 80% in each region, indicating that the inner layer was dominated by fine particles. Furthermore, the proportion of particles decreased in each region of two slags with the increase of particle size. The influence of particle system on the slag formation and shedding process was proposed. The accumulation of small particles was the cause of slag formation, while large particles had great influence on slag shedding. The presence of large particles increased the porosity and reduced the contact area between particles, the binding force between the particles was weaker than that between particles and tubes. Therefore, the fracture location of two slags was different, which made the internal surface presented different appearances.

Effect of silica fume on efflorescence formation and alkali leaching of alkali-activated slag

Alkali-activated cements (AACs) produced from industrial by-products have attracted great attention as an alternative to Portland cement, mainly because of the reduction of carbon dioxide emission and low energy consumption. However, AACs often suffer from severe efflorescence when subjected to humid environments because of their high soluble alkali content. This study reports the effect of silica fume on alkali leaching and efflorescence formation of alkali-activated slag. Specimens were prepared from ground granulated blast-furnace slag (BFS) and silica fume, where sodium hydroxide and sodium silicate solution were employed as activator solutions. Sample produced from 100% BFS exhibited the fastest efflorescence formation and alkali leaching rate. Incorporating silica fume into alkali-activated slag reduced the mobility of alkali, resulting in the decrease of efflorescence formation. However, almost all sodium can be leached out from the samples after immersion in water for 28 d, indicating the weak bond of sodium in the gel.

A Study on Bituminous Coal Base Acid Ratio to the Slagging Factor at Large Scale Boiler

Different types of coal have different characteristics and performances. In thermal coal plant, deposition of coal ash inside the furnace causes slag formation inside the boiler rear path and consequently reduces the heat transfer process and boiler efficiency. Besides, accumulation of ash on the boiler tube surfaces form layers of slags and blocks the flue gas flow out of the boiler. Therefore, the purpose of this study is to investigate the relationship between sub-bituminous coal base acid ratio towards the heat transfer process inside large-scale boilers. The base acid ratio for sub-bituminous coal is measured before firing inside large-scale boiler of studied the thermal plant which has a generation capacity of 700 MW. This study found correlation between high furnace rear path temperature (FRPT) that is observed to be above 800℃, with the build up of ash accumulation inside the boiler, for the studied coal. Thus, a high base acid ratio causes the accumulation of coal ash, thus reducing the heat transfer process which results in high FRPT of the boiler. Therefore, it proves that a base acid ratio is an indicator for coal performance during firing inside the boiler.

Investigation on Ash Fusion and Slagging Properties of Coal under Reducing Atmosphere

ABSTRACT Liquid slag tapping at low operation temperature is a major challenge for the application of entrained-flow slagging gasifier. To obtain and elucidate a regulation on stable liquid slag tapping, the SiO2-Al2O3-(CaO+MgO+Na2O+K2O)-Fe2O3 phase diagrams of ash fusion temperatures as well as the ash viscosity and components were studied with ash fusibility apparatus, high-temperature viscometer, SEM-EDS and FactSage software. Meanwhile, the potential slagging properties were analyzed by the difference between soften temperature and deformation temperature (DSI), base/acid ratio (B/A) and slag viscosity index G. Results indicated that the contours of fluid temperature (FT) in the SiO2-Al2O3-(CaO+MgO+Na2O+K2O) pseudo-ternary diagrams presented inverted V-shaped distribution. Attributing to the positive effect of Al2O3 and the downward parabola effect of SiO2, the FT first decreased and then increased with the increased SiO2/Al2O3 at the minimum value of around 3.25. Also, with the increase of (SiO2+ Al2O3+ CaO+MgO+Na2O+K2O)/Fe2O3, the FT showed a V-type distribution with a minimum value at 94:6, yet the effect of Fe2O3 was slight. Besides, high content of CaO+MgO+Na2O+K2O effectively reduced the FT, which favored the formation of molten slag and operation economy; but it shortened the DSI, disadvantaging the formation of long slag and the operation stability. Moreover, decreased ratio of (CaO+MgO)/(Na2O+K2O) not only reduced the FT, but also enlarged the DSI. Finally, a regulation method concerning stable liquid slag tapping at low operation temperature based on ash fusion and slagging properties was proposed: adjusting SiO2/Al2O3 to 3.25 and the mass ratio of Fe2O3 nearby 6.0 wt.%, and doping CaO+MgO+Na2O+K2O with low (CaO+MgO)/(Na2O+K2O) ratio could effectively reduce the FT and viscosity and enlarge the DSI simultaneously, and vice versa.

Melting Characteristics of Coal Ash and Properties of Fly Ash to Understand the Slag Formation in the Shell Gasifier.

The flow temperature (FT) of the coal ash from the Liuqiao no. 2 mine in North Anhui Province (C00) is too high (∼1520 °C) to fit the Shell gasifier due to its relatively high content of SiO2 and Al2O3. To solve this problem, a series of coals were blended with C00 with different ratios, and the relations between FT and the ash composition were investigated. The coal ash was analyzed by X-ray diffraction, Fourier transform infrared (FTIR) spectroscopy, and scanning electron microscopy–EDX to elucidate the mechanism of the improved ash fusion performance and the slag formation in the waste heat boiler of the gasifier. It is shown that FT is relevant to the coal ash compositions as well as the structures formed at high temperatures. The existence of alkaline oxides (CaO, MgO, and Fe2O3) decreases the coal ash FT to a low level. The FT can decrease to <1350 °C to cater to the Shell gasifier by blending C00 and C03 with a mass ratio of 4:6 owing to the plentiful alkaline oxides in C03. The FTIR results indicate that the high flow temperature of C00 is attributed to the formation of mullite at high temperatures. The coal blending with various ratios changes the compositions of CaO, MgO, and Fe2O3, which can form some low-melting-point eutectic compounds with SiO2 and Al2O3 under high temperatures, inhibit the formation of mullite, and thus decrease the ash FT. The coal ash FT was found to have a good linear relation with the ash compositions, which can sever as a reference to the coal blending. According to the model parameters, it is shown that Mg has the most significant promoting effect on the decrease in FT of the coal ash. The caking tendency of fly ash increases with the rising Ca content and an excessive Ca-based fluxing agent used in the coal blending will lead to the aggregation of the Ca-rich clasts around the fly ash particle, resulting in the plugging of the waste heat boiler in the gasifier. Therefore, the Mg-based fluxing agent is more promising to improve the ash fusion performance and reduce the caking tendency of the coal fly ash.

GENERALIZATION OF ALGORITHMIC MODELS FOR ORE SMELTING FURNACE OPERATION

This article establishes the relationship between the various processes that take place in the furnace. Specifically: - heating of the charge due to its electrical resistance; - introduction of additional heat due to coke burning; - heat transfer processes in the volume of the furnace bath; - formation of melt and slag due to chemical reactions. The complete algorithm of operation of the ore-thermal furnace is presented. By means of which it becomes possible to model in dynamics the technological process of obtaining ferroalloys. Literature sources are presented, where a more detailed mathematical description of modeling the ferroalloy smelting process is presented. The model is reconfigured when changing the parameters of the charge, depending on its component composition and temperature value. Such as: - electrical resistivity; - mass heat capacity; - specific density; - thermal conductivity. The described algorithmic model is universal for obtaining different brands of ferroalloys.

Nucleation of SiO_{2}-CaO-Al_{2}O_{3} Slag in Oxidative Ladle Refining of Metallurgical Grade Silicon

Oxidative ladle refining (OLR) is the most used refining method in industrial production of metallurgical grade silicon. OLR is performed by purging the liquid alloy with oxygen-enhanced air at 1823 K to 1873 K, reacting with silicon and the primary slag forming impurities to a SiO_{2}-CaO-Al_{2}O_{3} slag. To further increase our capability to control this process, it is paramount to understand how the slag nucleates and forms, and represent it such that it is useful for predicting and controlling the process behavior. This work aims to formulate a comprehensive theoretical description of slag nucleation and formation at nano/microscale using classical macroscale thermodynamics, bridging these spatial regimes. To achieve this, the work argues that silica’s liquid structure allows its nuclei to exhibit “well defined” surfaces. Furthermore, silica is predicted to be highly surface active, so if its concentration is high while the slag nucleus is small, the SiO_{2}-CaO-Al_{2}O_{3} slag should retain silica’s surface properties. An experiment confirmed the surface active nature of silica in the SiO_{2}-CaO-Al_{2}O_{3} system. It was also shown that increasing the slag’s calcia concentration has a greater effect on the interfacial tension between the molten slag and liquid alloy than alumina, confirming industrial observations of the coupling between refining rate and relative alloy/slag composition.

Modeling of the BOF Tapping Process: The Reactions in the Ladle

A tapping process model of the steel from the basic oxygen furnace (BOF) addressing the reactions in the ladle is proposed. In the model, the effective equilibrium reaction zone (EERZ) method is applied to describe the steel/slag interfacial reaction. The equilibrium reactions in the bulk steel (steel/inclusion/lining wear) and slag (liquid slag/slag additions/lining wear) are considered. The thermodynamic library—ChemApp is used to perform thermodynamic calculation. The process model includes most of the actions during the tapping process, such as the additions of ferroalloys and slag formers, carryover slag entrapment and air pick-up. After the calibration by the industrial measurements of two plants, the model is applied to study the influence of the amount of carryover slag.

Direct microalloying of structural steels by boron from oxide system CaO–SiO&lt;sub&gt;2&lt;/sub&gt;–B&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt;–Al&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt;–MgO

The results of fundamental studies of the physicochemical properties of slags of the CaO–SiO2–B2O3–Al2O3–MgO system were used as the basis for the development of the technology for the formation of boron-containing slags in ladle-furnace units (LFU). The recommended composition of ladle slags (1–4% B2O3, 15% Al2O3 and 8% MgO) ensures the development of direct microalloying processes of steel with boron, low viscosity, not exceeding 0.32 Pa∙s, and preservation of sufficiently high refining properties. Colemanite (Turkey) was used as boron-containing raw material, having, %: 39–41 B2O3, 26–28 CaO, no more than 5% of SiO2 and 3% of MgO. The implementation of the developed technology of direct microalloying of structural steels of a wide grade composition by boron in the BOF shop of ArcelorMittal Temirtau JSC provided the boron content at the level of 0.001–0.008%, a decrease in the consumption of manganese-based ferroalloys from 0.3 kg/t of 08кп steel to 0.8 kg/t of steel 17Г1С-У, exclusion of additives into the ladle of ferroboron and fluorspar. The proposed mode of formation of slags of the recommended composition in the melt of LFU provided a sufficiently high degree of metal desulfurization in comparison with the existing production routes. For example, with pipe steel 17Г1С-У, despite a decrease in lime consumption by 500 kg per a heat and a decrease of the steel processing time at the LFU by 40 minutes, a high degree of desulfurization, reaching 66.7%, provided a sulfur content of 0.004% in the metal. Microalloying of structural steels by boron results in their high strength properties with invariance of plasticity apart from sufficiently high refining effect.

DEVELOPMENT OF DEVICE FOR RESTORATION OF PLACES FOR BEARINGS

Defects of case details include operation of openings under bearings within 0,2 - 0,4 mm on the party, operation of landing belts under sleeves. When restoring them, traditional methods are used: installation of repair bushings, application of polymer and electrolytic coatings, micron smelting, electrospark treatment, etc. Restored parts must have hardness and wear resistance with the parameters of the material of the reducing part (deviation 10 - 15%), have sufficient adhesion to the base metal, corrosion resistance in a humid environment, provide maximum contact area with the conjugate part, no pores, slag, foreign inclusions . The method of restoration must eliminate the thermal impact on the part and be cost-effective. Polymer compositions are usually brittle, subject to breakage and leaching. Surfacing causes warping of the part, bleaching of cast iron, the formation of slag and pores in the deposited layer. The electrospark coating method does not provide sufficient contact area with the conjugate part. The use of electrolytes for iron seats in some enterprises is aggressive, unstable, requires heating or the use of expensive thyristor power supplies, followed by machining, as the microhardness of precipitation reaches a large value depending on the composition of the electrolyte and process modes, have high internal voltage. The proposed device for restoring the bearings simplifies the existing method and meets the technical requirements of manufacturers in terms of machining accuracy (ovality, taper, coaxiality and surface roughness), provides high productivity (2 times higher than the productivity of specialized machines horizontally). and low cost (60 times lower than the cost of specialized machines).

Thermodynamic Modeling of Reduction of Cerium from Slags of CaO–SiO2–Ce2O3–15Al2O3–8MgO by Calcium Carbide Additives

Thermodynamic modeling of the reduction of cerium from slags of the CaO–SiO2–Ce2O3 system containing 15% Al2O4 and 8% MgO, with aluminum dissolved in the metal together with calcium carbide additives at temperatures of 1550 and 1650°C was performed using the HSC 8.03 Chemistry software package (Outokumpu) based on the simplex lattice planning method used to minimize Gibbs energy. The results of thermodynamic modeling are presented in the form of composition-property diagrams (equilibrium content of cerium in the metal) for temperatures of 1550 and 1650°C. It is shown that the formation of slags within a basicity range of 2–3 containing 1–7% Ce2O3 provides an equilibrium concentration of cerium in the metal varying from 1 to 7 ppm at a temperature of 1550°C. The displacement of slags in the area of increased basicity (up to 3–5) is accompanied by an increase in the equilibrium concentration of cerium in the metal up to 7–23 ppm with a content of 3–7% Ce2O3 and as a consequence an increase in the efficiency of the process of cerium reduction. At a temperature of 1650°C, the equilibrium concentration of cerium in the metal within the basicity range of 2–3 and having a Ce2O3 content of 1–7% varies from 2 to 12 ppm. The displacement of slags in the area of increased basicity (up to 3–5) is accompanied by an increase in the equilibrium concentration of cerium in the metal to 7–33 ppm with a Ce2O3 content of 3–7%. The positive influence of the temperature factor basicity of slags and the content of cerium oxide on the process of its reduction is qualitatively explained from the standpoint of the formation of the phase composition of the slags of the studied oxide system and the thermodynamics of chemical reactions of reduction of cerium with aluminum dissolved in the metal, as well as with aluminum dissolved in the metal together with calcium carbide additives.