Melting Furnace Research Articles

Effect of industrial grade raw materials and its associated impurities on first hydrogenation of BCC solid solution alloys

This study explores the effects of using industrial-grade raw materials on the hydrogen storage properties of body-centered cubic (BCC) solid solution alloys. Industrial scrap metals were chosen as the raw material, and the desired alloys were synthesized using a vacuum arc melting furnace. Instead of using pure vanadium (V), different inexpensive industrial substitutes such as low-grade vanadium (V), vanadium nitride (VN), vanadium oxide (VO), and ferrovanadium (FeV) were utilized. The crystal structure, morphology, first hydrogenation, thermodynamics, and cyclability of the prepared alloys were analyzed by using XRD, SEM-EDS, and XPS methods. The crystal structure and morphology analysis revealed multiphase alloys in all the prepared alloys and a Ti rich third phase in the VN sample, which was absent otherwise. The first hydrogenation was performed at room temperature under a hydrogen pressure of 2 MPa without any prior heat treatment. The VO alloy displayed negligible hydrogen absorption during first hydrogenation, while the V, VN, and FeV alloys showed maximum hydrogen storage capacities of 3.49 wt%, 2.47 wt%, and 2.18 wt%, respectively. The presence of oxygen hinders the activation of the VO alloy and requires two activation cycles to activate the sample. A short-term cyclability analysis showed a reversible hydrogen storage capacity of 2 wt%. The change in enthalpy of hydrogen absorption and desorption for V alloy were calculated to be −36.73 ± 8.6 and 57.34 ± 8.3 kJ/mol H2, respectively. One of the prominent advantages of utilizing scrap raw materials was the substantial reduction in overall raw material costs, which saw an impressive 95% decrease when compared to using pure raw materials. These results highlight the economic benefits of incorporating recovered industrial scrap into hydrogen storage alloys.

Simulation and Validation of Thickness of Slag Crust on the Copper Stave in the High-Temperature Area of Blast Furnace

The blast furnace is the dominant high-temperature reactor in the modern ironmaking industry. Iron oxide in iron ores can be converted to metallic iron through blast furnace smelting, and this high-temperature melting can be used to separate the molten iron from the gangue components. The formation and thickness of the hot-surface slag crust on the copper stave in the high-temperature area of the middle and lower parts of the blast furnace are crucial for the safe operation and long campaign of the blast furnace. To enhance the precision of determining the thickness of the slag crust in this specific region, samples were extracted from the hot surface of the copper cooler situated in the high-temperature area. This extraction was carried out during the maintenance procedure of the blast furnace stockline. Subsequently, the thermal conductivity and melting performance of the slag crust were measured. The slag crust thicknesses corresponding to the various temperature measurement sites of the stave were determined by developing a mathematical model for the heat transfer of the copper stave. The actual slag crust thickness measurement data were acquired while the blast furnace stockline was in operation, and the data were then utilized to corroborate the model’s predictions. A blast furnace with an effective volume of 3200 m3 was used to test the model. The average thickness of the hot-surface slag crust was computed for cases that occurred between 2020 and 2022. The data’s correlations with the blast furnace’s technical and economic indices during the same time period were examined. The findings indicated that the blast furnace’s operation indices improved with a thinner slag crust, but there was also a higher chance of damage to the copper stave’s internal cooling water pipes. Taking into account the technical and economic indices as well as a long campaign of the blast furnace, 150–200 mm is recommended as the appropriate average slag crust thickness on the surface of the copper stave in the high-temperature section.

Fluidization-melting characteristics of fly ash from municipal solid waste incineration

Fly ash (FA) from municipal solid waste incineration contains hazardous substances such as dioxins, furans, and heavy metals. Melting FA has proved to be an effective method for reducing volume and mass, while also rendering the waste harmless. However, during the melting process, the addition of a fluxing agent with calorific value is currently necessary to increase melting capacity and reduce energy consumption, which presents a challenge. To tackle this issue, a fluidization-melting technology for a fuel/FA mixture is proposed, wherein a fuel source is employed in the melting process, producing ash that can serve as a fluxing agent. To test this approach, rice husk (RH) was utilized as fuel in a small-scale fluidization-melting test. The objective of this study was to examine the operation parameters of the platform and the characteristics of the resulting product, and to evaluate the harm reduction effect of the slag and its potential for resource utilization. The operating temperature was set at 690 °C in the thermal modification unit and at 1450 °C in the melting furnace, resulting in stable operation and continuous liquid slag discharge. The leaching toxicity of heavy metals in the obtained slag was lower than the standard limit, achieving harmless disposal of FA. However, the resource utilization potential of the obtained slag is limited due to its failure to meet the criteria of vitrified substance and environmental quality requirements. These limitations could be addressed by promoting the combustion of carbon in the melting furnace and accelerating the cooling rate of the slag in the quenching unit.

EVALUATION OF THE EXHAUST FLUE GAS ENERGY THERMOCHEMICAL RECOVERY EFFECTIVENESS FOR A SUBMERGED GAS COMBUSTION MELTING FURNACE

One of the main indicators of the technological process perfection is the exhaust streams material and energy resources utilization degree. This is especially important for high-temperature processes with a high external energy consumption level in metallurgy, glass, mineral wool, etc. Traditional methods of exhaust heat utilizing to burner air heating by various recuperators designs provide a no more than 60 % heat recovery rate, mainly because of the limited recuperators materials heat resistance. Preliminary theoretical calculations and some available practical implementations experience indicate that with high-temperature exhaust gases (> 800 °C) the thermochemical method of their heat recovery becomes promising for the hydrocarbon fuels conversion, primarily natural gas methane, in order to obtain a higher-potential fuel with increased accumulated energy density. The efficiency of thermochemical recovery due to equipping a high-temperature submerged combustion melting furnace by exhaust gas temperature of at least 1200 °C with an additional thermochemical reactor were evaluated. Bibl. 16, Fig. 6, Tab. 3.

Improved back propagation neural network method for predicting sulfur content in hot metal

Blast furnace smelting is a traditional iron-making process. Its product, hot metal, is an important raw material for the production of steel. Steelmaking efficiency can be improved and steel product quality can be stabilized by using proper hot metal. Sulfur is an important indicator reflecting the quality of hot metal, it is necessary to establish an accurate prediction model to predict the sulfur content of hot metal, to effectively guide the production process. There is a non-linear relationship among the factors influencing the desulfurization effect during the blast furnace smelting process, and the back propagation neural network (BPNN) model has a strong ability to solve nonlinear problems. However, BPNN has the disadvantages of slow convergence speed and easy to fall into local minima. To improve the prediction accuracy, an improved algorithm combining Kmeans and BPNN is proposed in this paper. The study showed that compared with the BPNN model and case-based reasoning (CBR) model, the Kmeans-BPNN model has the lowest RMSE and MAPE values, which indicates a high degree of fit and a low degree of dispersion. The Kmeans-BPNN model has the largest HR value, which indicates the highest prediction accuracy. The proposed Kmeans-BPNN prediction model achieves a hit rate of 96%, which is 4.5% higher than before the improvement. It can effectively improve the prediction accuracy of hot metal sulfur content.

Industrial Technologies for CO2 Reduction Applicable to Glass Furnaces

In recent years, the European Union’s legislation about sustainable development has promoted the gradual decarbonization of all industrial sectors, pushing towards the final goal of a carbon-neutral European glass industry in 2050. Moreover, the COVID-19 pandemic, the war in Ukraine and the consequent natural gas supply crisis have led to significant increases in the costs of traditional energy commodities and CO2 emission allowances. In this scenario, the European glass industry, which is both an energy-intensive sector and a large emitter of CO2, needs to reduce its specific energy consumption, change its energy sources and decarbonize its production process. In order to understand and support this metamorphosis of the glass industry, the follwing questions must be answered: are the technologies reported in scientific publications merely theoretical exercises, or can they be adopted by the industry? In what timeframe can they be adopted? The aim of this study is to review consolidated and emerging technologies applicable to the glass industry and investigate which ones can be implemented in the short or medium term to reduce energy consumption and CO2 emissions related to the glass production process. This study is based on a review of the literature, the materials presented in technical conferences and the opinions of interviewed experts. This study showed that the literature is not very substantial, lacking detailed information on technologies and their effects in terms of energy savings or emissions. More information can be found in the proceedings of selected specialist conferences. This study found that, on one hand, some technologies are mature and only adopted when economically viable, and appropriate boundary conditions are available; the state of the art regarding these technologies was already extensively covered in past publications (e.g., cullet pre-heating). On the other hand, there are many promising technologies in the research or testing phase (i.e., steam methane reforming, process electrification, use of hydrogen); in-depth studies about them are limited due to the novelty of the solutions that they propose or not available due to industrial secrecy issues. In addition to periodicals and specialized conferences, interviews were carried out with managers and technicians from industry, as well as technicians from the Italian glass research institute and industrial machinery producers (especially melting furnaces). The interviews represent added value of this publication, useful in helping us to truly understand the state of the art and degree of readiness of the technologies identified. In addition, the production values of the glass industry were studied: our research confirmed that the most important sub-sectors are flat and container glass, as well as the largest glass-producing nations/continents. Finally, a review of specific energy consumption and CO2 emissions indexes was carried out.

INTEGRATION OF OPERATION OF REGENERATORS OF GLASS FURNACES

The material of the article relates to the glass industry, namely to equipment for cooling the roof of regenerators of glass melting furnaces and can be used in the construction of new or reconstruction of existing regenerators.
 When the refractories of industrial glass melting furnaces are destroyed, an intensive decrease in the wall thickness of the melting basin occurs, which leads to a significant increase in the temperature of the outer surface of the walls and, accordingly, an increase in heat losses. The maximum destruction of the refractory masonry of the walls of the melting basin is observed at the level of the mirror of the melted glass. There is uneven wear along the height and perimeter of the pool. The rate of destruction of the masonry is determined by the stability of the used refractories, the temperature regime of glass melting, and the design features of the units.
 The technical task of the article is: to increase the service life of the refractory masonry of the glass furnace regenerator roof; utilization of the heat of the outer masonry surface of the regenerator roof, as well as improvement of its cooling system by using water cooling of the outer surface of the regenerator roof; saving fuel consumed to heat the same amount of coolant in boiler equipment.
 The proposed cooling of the outer surface of the regenerator roof makes it possible to: reduce the temperature of the outer surface of the roof to the level of 30 °C and at the same time make the most of the heat of the outer surface of the regenerator roof, which has not been used before, for example, to obtain hot water from a heat supply system, and this makes it possible to save fuel costs, which are necessary for the operation of boiler equipment to heat the same amount of coolant; to ensure a more uniform distribution of temperature fields over the entire plane of the regenerator roof by using flat collectors of a special design, which, in turn, makes it possible to slow down the process of destruction of the refractory lining of the regenerator roof. The thermocouples installed in the pipelines make it possible to monitor the change in the temperature of the coolant in the collectors, and in the event of an increase in the surface temperature of the collectors, the automation increases the flow of the coolant in the pipelines. The collectors are equipped with pressure valves, when the temperature of the coolant in the collector is above 100 °C, it can boil in the collector and then the pressure valve equalizes the pressure in the collector.

Exploration of synthesis route and effect of Ni-doping on thermoelectric performance of CoSb3

CoSb3-based materials have surfaced as promising contenders for mid-temperature thermoelectric (TE) applications owing to their low cost and stability. The current work focuses on designing three different synthesis routes and their comparison to find out the most suitable route for synthesizing pristine CoSb3. The designed synthesis routes are direct spark plasma sintering (SPS), conventional furnace melting followed by SPS, and arc melting followed by SPS. Based on structural and transport characterizations, the synthesis route of arc melting followed by SPS was handpicked amongst the three different synthesis routes. The key benefit of this synthesis route is the massive reduction in synthesis time and efforts without compromising the TE performance. Finally, to analyze the effectiveness of the optimized synthesis route, Ni-doped CoSb3 alloys were also synthesized, and the properties were studied. The effect of “Ni doping” on TE properties of CoSb3 alloys, resulted in n-type conduction, and an enhanced figure-of-merit (ZT) ∼0.61 at around 870 K for optimized composition Ni0.07Co0.93Sb3.

Effect of boron content on microstructure evolution and crystallization behavior of Fe7(CoNi)93-xBx (x=15, 18, 21) eutectic high-entropy alloys

The effect of boron content on microstructure evolution, glass-forming ability and crystallization behavior of Fe7(CoNi)93-xBx (x = 15, 18, 21) eutectic high-entropy alloys (EHEAs) was investigated. Bulk Fe7(CoNi)93-xBx EHEAs and ribbons were prepared by vacuum frequency induction melting furnace and melt-spinning method, respectively. The results show that the microstructure of as-cast hypoeutectic Fe7(CoNi)78B15 alloy consists of primary (Fe, Co, Ni) dendrite and lamellar eutectic. The eutectic Fe7(CoNi)75B18 alloy shows a fully lamellar eutectic structure consisting of (Fe, Co, Ni) phase and B-rich phase. The microstructure of hypereutectic Fe7(CoNi)72B21 alloy exhibits primary B-rich dendrite and lamellar eutectic. The as-spun Fe7(CoNi)75B18 and Fe7(CoNi)72B21 alloys show an amorphous structure. By comparison, the hypereutectic Fe7(CoNi)72B21 alloy shows an excellent glass-forming ability and thermal stability, which is attributed to the increase of crystallization activation energy induced by B addition. In addition, the increase of B addition inhibits the crystallization behavior, which is caused by the formation of stable covalent bonds between boron and other elements. This work provides an alternative route for the preparation of metallic glass by introducing the non-metallic boron component.

Research on oxygen enrichment for municipal solid waste fly ash melting: A pilot-scale study on natural gas and coal as the melting fuel

High energy consumption is the main obstacle of melting/vitrification technology for the disposal of municipal solid waste incineration fly ash (MSWIFA) for industrial applications. To reduce energy consumption and lower operating costs, oxygen enrichment melting was proposed and studied in this work. This research was conducted in a pilot-scale melting furnace, and three melting conditions were compared and discussed. The results showed that 66% of natural gas was saved and the operating cost was reduced by 55% when oxygen enrichment technology was applied to MSWIFA melting. When coal was used as the fuel with the oxygen enrichment melting technology, the operating cost was even lower at 66.39 dollar/ton of fly ash. Because MSWIFA was a Ca-rich material, the relatively high content of Si and Al in the coal fly ash promoted the formation of vitrificated slag, leading to a reduction in the overall pollution toxicity index (OPTI) of MSWIFA by 99.98%. Meanwhile, SO2, HCl, and secondary fly ash were the main pollutants during MSWIFA melting, and when coal was used as the fuel, the emissions of SO2 and HCl could be reduced and the OPTI of secondary fly ash was suppressed. These results suggested that to obtain the lowest operating cost and reduce secondary pollution during MSWIFA melting, the best option consisted of oxygen enrichment technology with coal as the fuel.

Effects of Fe and Cr on the microstructure and mechanical properties of FexCr72−xNi14Al14 high-entropy alloys

Cobalt-free lightweight FexCr(72−x)Ni14Al14 (x = 34, 36; at%) high-entropy alloys were designed and prepared in this study to determine the effects of Fe and Cr content variations on the microstructure and mechanical properties of the alloys. Both alloys were prepared from pure metals using a vacuum arc melting furnace. The microstructures of the alloys were characterized using various analytical methods and the macroscopic compressive mechanical properties and microscopic creep properties were investigated. Both alloys were composed of a disordered α(Fe-Cr) body-centered cubic matrix and ordered (Ni-Al) B2 nanoparticle precipitates, with the differently sized nanoparticle precipitates and micron grains forming a four-stage layered structure. The alloys exhibited excellent compressive properties with a maximum yield strength of 1378 MPa, compression ratio of 34.1 %, and high specific yield strength of 210 kPa·m3/kg. Dense geometrically necessary dislocations (GNDs) were observed in the grains of the two as-cast alloys. GND was the main deformation mechanism in the early stages of creep, and the GNDs and B2 precipitated phase became obstacles to dislocation movement, which improved the creep resistance of the alloys. Excellent mechanical properties and good economy have great attraction in structural materials

Effects of pellet ratio on the burden movement and distribution characteristics in the BF throat

In order to solve the urgent problem of energy conservation and emission reduction in the iron and steel industry, the use of high proportion pellets in blast furnace smelting will be the trend of ironmaking development in recent years. In the present work, a geometric model of a serial-hopper bell-less type charging system based on the discrete element method was built, which was used to investigate the distribution behavior of burden under the condition of multi-ring charging and different pellet ratios. The results show: (1) the overall velocity and particle flow width of the burden at the chute outlet become larger which results the average radius of falling point increases. (2) The pellet ratio has a significant effect on the distribution characteristics and the burden profiles at the furnace throat. When the pellet ratio increases from 0% to 100%, the relative radius of peak position of the burden layer increases from 0.491 R to 0.639 R, while the peak height decreases from 0.860 m to 0.543 m. (3) The burden segregation occurs at both the radial and longitudinal positions of the layer. In the radial position, the distribution of pellets near the center is relatively concentrated compared with sinter and there is no burden segregation occurs near the relative radius of 0.590 R. In the longitudinal position, the pellets are mainly distributed at the bottom of the burden layer, while the upper part is relatively less distributed. The research content and results may give a reference for the charging operation of BF under the condition of large pellet ratio, and consequently reduce CO2 emission in ironmaking process.

Alternative Industrial Chrome-Free Alumina-Based Bricks for Copper Alloy Melting Furnaces

Abstract In this study, the corrosion resistance of alumina-based bricks against the slag of copper alloy melting furnaces was investigated. Four commercial chrome-free alumina bricks have been studied. Bulk density and apparent porosity measurements and phase analysis of the bricks were performed. The most important property, the slag corrosion resistance, was evaluated at the temperature of 1,200°C for 2 h. The microstructures of the bricks, their penetration depth, and corrosion index were evaluated. The results showed that two bricks showed acceptable corrosion resistance against the slag. The low corrosion index of these bricks was attributed to their aluminosilicate phases (sillimanite, or andalusite) and lower phosphate bonding; however, the problematic matter was the silicate phase, which showed lower resistance against the penetration of slag. It was observed that the aluminosilicate phase can improve the corrosion resistance through the reaction with slag, whereas the presence of large alumina aggregates can restrict the penetration of slag.

The effects of antimony and hot rolling on the microstructure, texture, and magnetic properties of a non-oriented electrical steel

The present work investigates the effects of antimony and hot rolling on the microstructure, texture, and magnetic properties of a 1.2 wt%Si electrical steel. For this purpose, three samples with 0.002, 0.012, and 0.026 wt% antimony were produced by melting in an induction furnace and casting into ingots, followed by hot rolling with a 75 % reduction. The aim was to better understand the interaction effects of adding antimony and hot rolling on the microstructure, texture, and magnetic properties. Microstructural studies were performed using optical microscopy (OM) and field emission scanning electron microscopy (FESEM). The macrotexture measurement was performed via X-ray diffraction (XRD), while magnetic properties were measured by a vibrating sample magnetometer (VSM). The results showed that increasing the antimony content gradually reduces the grain size, which is due to the effect of antimony on the migration rate of grain boundaries. This behavior was observed in both as-cast and hot-rolled samples. The texture in as-cast samples is random, and θ-fiber is observed after hot rolling. The examination of the texture parameter (TP) showed that the sample with 0.002 wt%Sb has a higher TP compared to other samples. Moreover, the lowest levels of coercivity and remanence are observed in this sample, which is due to the inverse relationship between the grain size and coercivity. The addition of antimony reduces the grain size, thus destroying the magnetic properties under these conditions.

Investigation on Nonisothermal Dehydrogenation Behavior of Mg–Ni–La–H Materials Prepared by Mechanochemical Reaction

Mg10NixLa–H alloys are synthesized by mechanochemical reaction starting with Mg–Ni–La multiphase polycrystalline alloys prepared by resistance melting furnace. The nonisothermal hydrogen desorption behaviors are investigated herein. All prepared samples are characterized by scanning electron microscopy, X‐ray diffraction, fully automatic fast surface and porosity analysis meter Brunauer–Emmett–Teller (BET), differential scanning calorimetry, and thermogravimetric analyzer to get information of phase compositions, microstructure, BET surface area, and dehydrogenation properties. The results demonstrate that Mg10NixLa–H exhibits enhanced nonisothermal hydrogen desorption behavior owing to the synergistic effects among hydrides. The main peak dehydrogenation temperatures for Mg10Ni5La–H, Mg10Ni10La–H, and Mg10Ni15La–H alloys are 375.3, 374.4, and 359.7 °C at 5 °C min−1, respectively. And the apparent activation energy for Mg10Ni5La–H, Mg10Ni10La–H, and Mg10Ni15La–H is 111.7, 275.5, and 184.7 kJ mol−1, respectively. However, the actual hydrogen release capacities of Mg10Ni5La–H, Mg10Ni10La–H, and Mg10Ni15La–H are about 5.09, 3.98, and 4.49 wt%, respectively. Mg10Ni15La–H exhibits the lowest onset dehydrogenation temperature due to its reduced particle size and uniformly distributed hydride phase. The modification of Mg‐based hydrogen storage materials by combining mechanochemical reaction and multiple microalloying is essential for further improvement of thermal properties.

Effect of the Presence of Structural Defects on the Superconducting Properties of (NbTa)0.67(MoHfW)0.33 and Nb-47wt%Ti

A comparison of the results of studies on the influence of structural defects on the critical parameters of superconductivity has been made for the high-entropy alloy (NbTa)0.67(MoHfW)0.33 and for the conventional superconducting magnet material Nb-47wt%Ti. Positron annihilation lifetime spectroscopy (PALS), electrical resistivity, magnetization and magnetic susceptibility measurements were used. In addition, X-ray powder diffraction studies were performed on the high-entropy alloy (NbTa)0.67(MoHfW)0.33. Due to the rapid cooling of the materials after melting in the arc furnace, they contain a higher concentration of structural defects compared to the heat-treated materials. Magnetic property measurements showed that both the critical temperatures Tc and the upper critical fields μ0Hc2 of bulk superconductivity-related materials are improved in the presence of structural defects.

An Analysis of Long-Process Ironmaking in a Reduction Smelting Furnace with Hydrogen-Enriched Conditions

The blast furnace and basic oxygen furnace (BF-BOF) is still the main process used for the production of iron and steel in China. With the approach of the “dual carbon” target, the iron and steel industry needs to transform and upgrade to “green” and “low-carbon” practices. At present, the low-carbon hydrogen metallurgy technology route based on hydrogen instead of carbon is mainly adopted at home and abroad, and the domestic route is mainly based on oxygen-rich BFs and hydrogen-based shaft furnaces (SFs). It promotes the transformation of the traditional BF to hydrogen-rich, oxygen-rich, and carbon-recycled (Hy-O-CR) technology. A new ironmaking system and method for a reduction smelting furnace (RSF) with Hy-O-CR is presented in this paper. The ironmaking system includes nine sets of equipment, such as an RSF, gas dust collector, dryer, CO2 separator, electrolytic water device, blower, heat exchanger, storage tank of reduction gas, and chimney. From top to bottom, the RSF includes an indirect reduction zone, a soft melting dripping zone, and a coke combustion zone. The ironmaking methods include coke and ore mixed charging, injection of the mixed reduction gas composed of electrolytic green hydrogen and circulating gas from the furnace gas into the indirect reduction zone, injection of oxygen into the coke combustion zone, CO2 recovery of the furnace top gas, and slag and iron treatment. By redesigning the size of the furnace type and optimizing the parameters, the metallization rate of the indirect reduction zone can be as high as 85–95%, and the carbon consumption per ton of hot metal can be greatly reduced. By using oxygen to recycle the reduction gas produced by its reactor, the process achieves the goal of reducing CO2 emissions by more than 50%, thus realizing green and low-carbon metallurgy.

Nanophase transformation and strengthening - Toughening mechanism of the Cu–15Ni–8Sn alloy during aging

The Cu–15Ni–8Sn alloy ingot was prepared in the medium-frequency induction melting furnace. The hot extruded alloy was treated by solid solution at 840 °C for 60 min and aging at 400 °C for different times (0 miñ480 min). The effect of aging time on the evolution of the nanophase of Cu–15Ni–8Sn alloy and the strengthening-toughening mechanism were studied. The results show that at the beginning of aging, the alloy undergoes spinodal decomposition, the wavelength of the modulated structure is approximately 3∼7 nm, the ordered phase transformation of D022 and L12 occurs simultaneously, and the ordered phase size is approximately 5 nm. With the extension of aging time, the modulated structure became coarser, and the wavelength of the modulated structure increased to 5–9 nm. At the same time, the D022 ordered phase changed to the L12 ordered phase, and a continuous distribution of elliptical discontinuous precipitation appeared at the grain boundary. The ratio of the long and short axes of the discontinuous precipitation was approximately 4.7. In the late aging period, the D022 ordered phase was basically transformed into the L12 ordered phase, and discontinuous precipitation, which is incompatible with the matrix, extended into the crystal. After 120 min of aging at 400 °C, the hardness, strength, and elongation of the alloy are 105.4 HRB, 839.8 MPa and 9.6 %, respectively. The peak-aging states D022 and L12 coexist in an orderly phase at the nanoscale, and this nanoscale strengthening phase is completely integrated with the matrix, which improves the strength and toughness of the alloy. The research results can provide support for the development of high-performance copper alloys in the ocean.

Characterization of firebricks used in copper smelting furnaces of the 19th century, Atacama, Chile

In the 19th century, mining in northern Chile was of great economic importance. Today, the ruins of the copper smelters and abundant fragments of refractory bricks from their furnaces remain. The refractory materials have not been previously studied. the origin, physical and chemical properties, and compressive strength of 10 different samples of historical refractory bricks collected on-site were investigated. The characterization results showed that the bricks are silico-aluminous, unlike the magnesium-chromium bricks used by current foundries. It was determined that 90% of them were produced in the UK and 10% were manufactured in Chile. The phases present are mullite, quartz, cristobalite, and tridymite, and the chemical composition corresponds mainly to SiO2. The compressive strength of the historical bricks is similart to those currently used,. These results may contribute to the knowledge of the 19th century mining and metallurgical historical heritage of Chile and the UK.

Justification of an acceptable modern energy-efficient method of obtaining sodium silicate for production in Kazakhstan

Sodium silicate is used in various industries. Sodium silicate is a basic component in the production of silicate adhesives and paints, silica gel, welding electrodes, corrugated packaging, and geopolymer concretes and cements. All this is currently not produced in the Republic of Kazakhstan. The article discusses the methods of production of sodium silicate and substantiates the possibility of organizing production in the Republic of Kazakhstan. The authors have studied all the available experience in the production of sodium silicate, both now and in the past. At this stage of the research, an analysis was made of the experience in the production of serial and pilot sodium silicate in the USSR in the past and in countries where development has not been suspended at the present time. All possible sources of raw materials of technogenic and natural origin were studied. Business trips and expeditions to natural deposits were carried out and samples of raw materials from various natural and man-made sources were delivered. Studies have been carried out to determine the available volumes of raw materials. Various technologies for melting sodium silicate have been studied, incl. by unconventional schemes, such as smelting in cyclone furnaces. For melting in electric furnaces, various schemes of energy-saving methods for melting sodium silicate were analyzed. Promising ones have been identified. The following types of sodium silicate production were analyzed in the study: traditional smelting (carbonate method), wet method, sodium chloride sublimation method, sulfate method, cullet smelting. The optimal variant has been chosen, which makes it possible to reduce the cost of electricity by several times when introducing a highly efficient innovative technology of electric melting into practice.