Energy Technology 2024

Under the modern blast furnace process conditions, replace the coke or pulverized coal by hydrogen; improve the efficiency of hydrogen reduction in the blast furnace; realize carbon-hydrogen coupling reduction in different process section and temperature range; give full play to the advantages of carbon direct reduction, CO indirect reduction, and H₂ reduction in heat transfer, mass transfer, momentum transmission, and metallurgical reaction engineering, through process development and operation optimization; reduce carbon fuel consumption and blast furnace fuel ratio to below 460 kg/t; and realize rich hydrogenation and low carbonization of blast furnace iron making process. The changes of theoretical combustion temperature of tuyere raceway and bosh gas volume of the blast furnace are researched. The reduction thermodynamic parameters of different temperature range and zone of blast furnace are calculated. The process measures of improving hydrogen utilization ratio and hydrogen carbon replacement ratio in the operation of blast furnace are discussed.

Economic and environmental pressures are driving change in the modern aluminum industry, compelling manufacturing sites to optimize their processes to drive down costs and reduce environmental impact. Secondary aluminum melting (recycling) requires only 5–10% of the energy needed to produce primary aluminum—reducing carbon emissions and providing cost savings for the producer and consumer but is still a major source of greenhouse gases because of the growing size of the secondary market. Significant improvements in carbon footprint and energy efficiency can be made to aluminum remelting by using smart oxy–fuel burners, low carbon intensity fuels, and Industry 4.0 tools. In this paper, we discuss different pathways to reduce total CO₂ emissions from secondary melting furnaces. First, a novel smart burner will be discussed. This next-generation oxy–fuel burner helps to reduce specific fuel consumption. The burner is a ‘transient heating’ burner that enables automatic control of energy into various locations of the furnace, based on feedback from furnace sensors. Second, we discuss how the use of low carbon intensity fuels like hydrogen and ammonia can help reduce or eliminate CO₂ emissions. Finally, we present how the use of oxy–fuel combustion technology combined with low carbon intensity fuel can help optimize overall energy cost for secondary melting furnaces. These pathways can assist manufacturers in choosing the optimal solution to decarbonize their melting furnaces.

Iron concentrate can be obtained from vanadium titanium bearing magnetite ore through beneficiation, which mainly recovers iron and vanadium resources through the process of blast-furnace ironmaking and converter vanadium extraction. However, this process has the bottleneck problems of large carbon emission and high process energy consumption, which does not meet the development trend of green and low-carbon smelting. Based on hydrogen metallurgy technology, the reduction and carbonization of iron concentrate in hydrogen-rich gas system (CH₄–H₂ gas mixture) was studied in this paper. The theoretical calculation results show that the Fe-containing phase in iron concentrate could be completely reduced and carbonized to Fe₃C above 709 °C, while Fe₃C cannot exist stably below 900 ℃. The experimental results are basically consistent with the thermodynamic results. The results preliminarily confirm the feasibility of producing high value-added product Fe₃C from iron concentrate by hydrogen-rich gas, which provides a possible way of smelting iron concentrate.

One of the major problems in modern society is the huge demand for energy which has as a consequence an enormous amount of waste gas production. Composite materials based on polyethylene oxide matrix and inorganic zeolite powders have been observed to show good properties in the field of carbon dioxide separation. In previous experiments, it has been shown that PEO-zeolite-based membranes show good performance at temperatures up to 398K both in dry and wet conditions. In this work, the influence of the pressure of the waste gases as well as the influence of the partial pressure of the carbon dioxide in the mixture on the overall performance of the membrane were tested.

In the pursuit of economic growth and value creation, foundation industries including cement, metals, glass, chemicals, paper, and ceramics face formidable challenges related to energy usage, emissions, and resource consumption in their manufacturing operations, all while striving to achieve ambitious Net Zero carbon and green targets. To overcome these challenges and propel sustainable progress, benchmarking emerges as a powerful ally. This study performs a benchmarking analysis of energy use and CO₂ emissions for a UK cement plant as well as best available techniques (BAT) investigation to identify opportunities for performance improvement in crucial areas such as energy usage and environmental sustainability. The research utilises industrial data from a 2850 tonne per day capacity dry process cement plant. Key energy and emissions parameters, including thermal and electrical energy intensity, recovered energy and CO₂ intensity, are computed per tonne of cement produced along with capacity utilisation across major process stages including raw material grinding, clinkerisation, and cement grinding. Comprehensive data sourced directly from the manufacturer is compared against literature benchmarks for global averages and best practices. Although surpassing global average values, the plant lags European best practices across all metrics, signalling room for substantial improvement. Assessment of relevant BATs for the cement industry reveals prospects to integrate vertical roller mills for cement grinding and use Organic Rankine Cycle (ORC) at the clinkerisation stage. Adopting these techniques could reduce the electrical energy intensity of clinkerisation by 51% and cement grinding electrical intensity by 30%, surpassing benchmarks. While limited to a single cement plant, the study provides a standardised methodology that could be replicated across foundation industries to enable performance tracking and highlight efficiency gaps. The benchmarking approach developed can guide the implementation of energy conservation measures and the adoption of best practices by the cement industry to reduce its carbon footprint.

The industrial demand for pure uranium and uranium compounds is tremendously increasing due to its wide array of utilities most especially in nuclear industries. Consequently, the treatment of a local boltwoodite ore containing albite (Na_2.00Al_2.00Si_6.00O_16.00: 96-900-1634), boltwoodite (Na_2.00K_2.77U_3.00Si_6.00O_9.00H_4.00: 96-900-7219), thorite (Th_4.00Si_4.00O_16.00: 96-900-7625), and quartz (Si_6.00O_6.00: 96-900-5019) was examined in sulphuric acid media. The experimental parameters such as leachant concentration, reaction temperature, and particle size on uranium ore dissolution were investigated. At optimal leaching conditions (2.5 mol/L H₂SO₄, 75 °C, and 75 µm), an 89.1% dissolution rate was achieved within 120 min. The estimated activation energy of 20.70 kJ/mol supported the diffusion control reaction mechanism as the rate-determining step. The leach liquor obtained at established conditions was further beneficiated to produce an industrial grade sodium diuranate (Na₂U₂O₇: 00-064-0473, density = 6.51 g/cm³, melting point = 1654 ± 2 ℃) proposed to serve as intermediate raw-material in a nuclear fuel cell.

Copper froth flotation tailings containing 1.19 and 0.97 wt% total and acid-soluble copper, respectively, from Chibuluma mines in the Copperbelt province of Zambia were characterized by SEM and XRD techniques. The major phases in the feed material were malachite, chrysocolla, pseudo malachite, chalcocite, quartz, biotite, orthoclase, calcite, etc. Screen analysis revealed that the tailings were coarse as only 9.17 wt% were less than 0.075 mm. With the purpose of establishing a low energy processing route, gravity concentration, froth flotation, and flotation–leach tests were carried out on the material. Gravity concentration upgraded copper up to 15.32 wt% at a cumulative recovery of 59.6%. On the other hand, a concentrate grade of 21.59 wt% was obtained via froth flotation but recovery was lower (49.68%). Therefore, the tailings from froth flotation were leached out and a leach efficiency of 97.92% was obtained such that the final tailings only had 0.02 wt%. As a result, it was concluded that the tailings should be processed via flotation–leach process to ensure maximum recovery of copper (both sulphide and oxide).

The stainless steel industry is increasing at a great pace every day. In addition, there is a need to increase the production capacities of FeCr and FeNi, which are the main input raw materials of stainless steel. However, FeCr and FeNi production processes with intensive energy consumption and high carbon dioxide emission values pose a problem when evaluated within the framework of the Paris Climate Agreement. As a result of these reasons, more environmentally friendly and more economical methods are sought. In this study, FeCr is produced by aluminothermic reaction to reduce the carbon footprint to almost zero in the smelting process and energy saving is aimed by exothermic reaction. In addition, FeCrNi production conditions were investigated by smelting in a single crucible instead of separately produced FeCr and FeNi. In addition, energy saving is achieved as it is fed in powder form without applying any agglomeration process as a preliminary preparation.

We present the mass balances associated with carbon dioxide (CO₂) removal (CDR) using seawater as both the source of reactants, and as the reaction medium via electrolysis following the “Equatic™” (formerly known as “SeaChange”) process (La Plante et al. in ACS EST Eng. https://​doi.​org/​10.​1021/​acsestengg.​3c00004, 2023). This process, extensively detailed in La Plante et al. (Chem Eng. https://​doi.​org/​10.​1021/​acssuschemeng.​0c08561, 2021), involves the application of an electric overpotential that splits water to form H⁺ and OH^– ions, producing acidity and alkalinity, i.e., in addition to gaseous co-products, at the anode and cathode, respectively. The alkalinity that results, i.e., via the “continuous electrolytic pH pump” results in the instantaneous precipitation of calcium carbonate (CaCO₃), hydrated magnesium carbonates (e.g., nesquehonite: MgCO₃·3H₂O, hydromagnesite: Mg₅(CO₃)₄(OH)₂·4H₂O, etc.), and/or magnesium hydroxide (Mg(OH)₂) depending on the CO₃^2– ion-activity in solution. This results in the trapping, and hence durable and permanent (at least ~ 10,000–100,000 years) immobilization of CO₂ that was originally dissolved in water, and that is additionally drawn down from the atmosphere within: (a) mineral carbonates, and/or (b) as solvated bicarbonate (HCO₃^–) and carbonate (CO₃^2–) ions (i.e., due to the absorption of atmospheric CO₂ into seawater having enhanced alkalinity). Taken together, these actions result in the net removal of ≈ 4.6 kg of CO₂ per m³ of seawater catholyte processed. Overall, this analysis provides direct quantifications of the ability of the Equatic™ process to serve as a means for technological CDR to mitigate the worst effects of accelerating climate change.

The progress of global industrialization is inextricably intertwined with the development of metallurgical technologies. Chlorine metallurgy is a pivotal technology that plays a crucial role in enhancing the utilization of intricate mineral resources, thereby facilitating their efficient processing. Chlorine metallurgy employs chlorinating agents to convert metals in raw materials into chlorides, thereby affecting the separation and purification of polymetals in an eco-friendly manner. The utilization of metallurgical chloride can concurrently achieve a substantial enhancement in the rates of recovery, purity, and cleanliness. The article examines advancements in the implementation of various chlorine metallurgy techniques, including processes such as chlorination roasting, chlorination melting, and chlorination refining. The challenges associated with chlorine metallurgy applications are presented, along with the identification of potential avenues for future research in the field of chlorine metallurgy.

In recent years, gallium has garnered significant attention in the semiconductor industry, which constitutes over 80% of the total demand. Gallium is widely dispersed in the Earth’s crust, while only two distinct deposits of this precious metal have been discovered—Gallite (CuGaS₂) and Soehngeite (Ga(OH)₃). Based on the current investigation, it is estimated that approximately 90% of gallium is extracted from the aluminum industry. Therefore, it is imperative for us to explore the synergistic extraction of aluminum and gallium from bauxite, which has been extensively studied by numerous researchers. This paper introduces the trend of gallium in the smelting process of bauxite, summarizing a comprehensive overview of the latest trends in the extraction method of gallium from the bauxite process such as ion exchange method, extraction method, fractional precipitation method, and electrolysis, comparing the advantages and disadvantages of each extraction method, which will guide the efficient extraction of valuable components from bauxite.

This study is focused on technoeconomics of supercritical fluid extraction (SCFE) technology as applied to the recovery of rare earth elements (REEs) from end-of-life neodymium iron boron magnets. The REEs are in increasingly high demand and due to their limited supply, their recovery from electronic waste is highly promoted. The supercritical fluid extraction (SCFE) process is recognized as a green alternative to hydro and pyrometallurgy to recover REEs from secondary resources. The technical feasibility of SCFE for recycling of REEs from end-of-life neodymium iron boron magnets has been proven in the past. Using a wide range of data sources including laboratory results, literature data, scaling models, scenario analysis, and sensitivity analysis, this study performs a sound economic analysis of the SCFE process at an industrial scale. A detailed estimation of the costs and revenues associated with the process is conducted and the primary factors that affect its profitability are identified. The findings demonstrate that the SCFE of REEs from neodymium iron boron magnets can be economically viable under certain circumstances, with the efficiency of extracting dysprosium and neodymium and the price of their respective oxides being the main drivers of profitability. By providing valuable insights into the technoeconomic feasibility of the SCFE process for REEs recovery, this study informs future research and development activities in the field.

Environmental, Social and Governance (ESG) rating is a key topic of attention by the industries, particularly for the companies trading in the stock exchanges. There is a lack of reliable, robust, and credible ESG rating tools. Mining, mineral processing, and metallurgical technologies are required to be evaluated by consistent and standard methodology to be used by the industries to claim their environmental performances. Life cycle assessment is one such methodology that can be integral to the environmental part of the ESG rating. However, there are several issues that needs attention by the practitioners specific to the mining and metallurgical products and processes. There are several factors such as defining boundary, data inputs, and allocation where multiple metals are produced with significantly different prices, dynamic nature of the changes of the energy sources, particularly, electricity and impact method selection. These make LCA studies challenging which need careful attention by the mining industry experts. Energy, carbon, water, and waste (ECWW) footprint of metals can be a generic simple score card for evaluating the environmental performance of metals, practically in many cases. These indicator results can be fed into the ESG rating tools for company performances in the stock market.

In light of the high alumina content (nearly 50%) in the high-alumina fly ash, high-alumina fly ash is considered a significant and promising alternative resource to bauxite. Towards the prevailing issues in the current process of extracting alumina from fly ash, a novel synergistic extraction of aluminum and silicon from high-alumina fly ash was proposed, which features carbochlorination with chlorine and carbon as raw materials. In this paper, the carbochlorination kinetics of aluminum and silicon was investigated. The results indicate that the carbochlorination process of fly ash conforms to the reaction model without generating solid byproducts. The carbochlorination of alumina and silica was governed by chemical reactions at 850–950 ℃, with an activation energy of 65.70 kJ/mol and 89.06 kJ/mol, respectively. The reaction series and the kinetic equation, which takes into account the temperature and partial pressure of chlorine gas were successfully determined.

Aluminum dross occurs while production of aluminum. Depending on the aluminum process such as primer or seconder, chemical composition varies. White dross occurs from primer aluminum production and it contains 20–80 wt% Al. Black dross occurs from seconder aluminum production and it contains 5–25 wt% Al. White dross is ground, so metallic part and non-metallic residue (NMR) can be separated. Since oxides are brittle and aluminum is ductile, they can be separated from each other due to their particle size. Metallic part is used to produce aluminum ingots and NMR is landfilled and when it reacts with groundwater or humidity, it has several hazardous effects to nature. In this study NMR was used to produce fused alumina in an electrical arc furnace. Direct smelting and calcination of dross conditions before smelting are investigated. Products were investigated with XRF and XRD techniques. 90–95 wt% Al₂O₃ containing fused alumina was produced.

The flash iron-making process is expected to be a new iron-making technology due to its nonuse of coke, pellets, sintered ore, and extremely high production efficiency. Hydrogen is an excellent reducing agent for flash iron-making with fast reduction rate and none CO₂ emission. In this study, the effect of hydrogen concentration and reduction temperature on reduction characteristics of Fe₃O₄ in a drop tube furnace was investigated using the computational fluid dynamics method. The results show that the Fe₃O₄ particles can be reduced in seconds. The reduction degree gradually increases with increase of hydrogen concentration and reduction temperature. The maximum metallization ratio can reach 88.95%.

The lead recovery process for automotive batteries is known to be not only a smelting process but also a chemical recovery process, including several reactions to have it done as pure metal (Pb). The traditional technology route includes shredded batteries, iron chips, and coal to reduce lead oxides into metallic lead. Although the market understands it as a usual process of direct reduction, therefore aiming reductant atmospheres and under-stoichiometric flames, SK Metais, through gas analyses, mass balances, and evaluation of the entire production stream, understood its process, chemical needs, and reactions, changing the standard process to become one of the most efficient facilities toward low emissions, and at meantime improving their throughputs.

By-product gas, steam, and electricity coupling system plays an important role in providing stable energy supply for steelworks. In this paper, a multi-period GSECS scheduling model with the objectives of economics and in-plant grid reliability was constructed. Economics is reflected in the reduction of gasholder penalty cost, electricity interaction cost, and carbon emission cost while the reliability is shown as the variance of the electric load. In GPC, a new method of defining gasholder penalty factor was designed to distinguish different types and operating intervals of gasholders. The NSGA-II was used to obtain the multi-objective Pareto solution set, and the optimal solution was filtered based on the improved AHP—entropy weight method. With a calculated example, compared to manual operations, the gasholder penalty cost was reduced by − 51.37% after optimization, as well as a reduction of 25.23% in the deviation of the gasholder, enhancing its stability. In addition, the variance of the in-plant grid was improved by 45.15%.

A three-stage cross-flow Venturi jet reactor was innovatively designed in this study to conduct an experimental study on the physical simulation of the carbonization process of calcified slag. The pH changes during CO₂ absorption by NaOH were measured by a pH meter. The influence law of superficial gas velocity, superficial liquid velocity, and inlet pressure on CO₂ absorption rate and utilization rate were investigated. The results show that the volumetric mass transfer coefficient with the increase of superficial gas velocity first remains unchanged and then increases, decreases with the increase of superficial liquid velocity, and increases with the increase of inlet pressure, and the latter stage is greater than the previous stage. The CO₂ utilization rate does not change with the increase of superficial gas velocity and inlet liquid velocity but increases with the increase of inlet pressure and remains unchanged afterwards. This result provides support for the design and industrial application of carbonization reactors.

The use of coke will be greatly reduced by much pulverized coal injection. The pulverized coal injection rate of blast furnace can be greatly increased by local oxygen-enrichment method. However, the cooling effect of room-temperature oxygen delays the devolatilization process and the entire coal combustion process will be delayed. To increase the pyrolysis rate will weaken the cooling effect of room-temperature oxygen on coal combustion. The pyrolysis rate increases and activating energy decreases with Fe₂O₃ addition. In this study, the effect of Fe₂O₃ on coal combustion in the blast furnace was simulated. The effect of Fe₂O₃ without oxygen enrichment on coal burnout is unobvious. For local oxygen enrichment, the coal burnout greatly increases and has a maximum increase of 22.03%.

Charge carbon composite briquette (CCB) is an effective method to reduce CO₂ emissions and save energy in blast furnace (BF) ironmaking. Presently with the hydrogen-bearing gas being injected in the BF, the content of H₂ and H₂O in the BF gas is comparable to those of CO and CO₂, and they could not be ignored in analyzing the CCB reaction behavior in the BF shaft. In this research, a mathematical model was developed for analyzing the reaction behavior of CCB under the H₂-H₂O-CO-CO₂-N₂ atmosphere. The model was one-dimensional. Chemical reactions, internal gas diffusion, and mass transfer between the CCB and the atmosphere were considered in the model. Using the model, the influence of gas composition and temperature on CCB reaction was discussed and the reaction progress was investigated. The simulation results showed that increasing temperature or increasing hydrogen in the atmosphere can prompt the reduction of iron oxide and the gasification of carbon in CCB. In the investigated temperature range, iron oxide reduction by hydrogen and carbon gasification by water vapor played important roles in the CCB reaction process.

The energy consumption of industrial ventilation systems plays an important role in industry building systems. The resistance of local components accounts for a large part of the total resistance of industrial ventilation systems. Reducing the resistance loss of local components is of great importance for improving the energy efficiency of a ventilation system. In this paper, ANSYS Fluent 18.2 software was used to research the resistance characteristics of the ventilation system with different flow deflectors. The results indicated that adding flow deflectors at the tee could maintain the air volume balance of the ventilation system, reduce the resistance loss, and increase the maximum reduction of resistance rate by 19% in the ventilation system. This study is expected to optimize the low-carbon and energy-saving operation of industrial ventilation systems.

The phase equilibria of the Ag–Ga–S–AgBr system in the part GaS–Ga₂S₅–AgBr–Ag₂S below 600 K were investigated by the modified electromotive force (EMF) method using the Ag⁺ catalysts as small nucleation centers of equilibrium phases. Division of the GaS–Ga₂S₅–AgBr–Ag₂S was carried out with the participation of the following compounds Ag₂S, GaS, Ga₂S₃, AgBr, Ag₉GaS₆, AgGaS₂, Ag₃SBr, Ag₃Ga₂S₄Br, and Ag₂₇Ga₂S₁₂Br₉. Reactions were performed by applying electrochemical cells (ECs) with the structure: (−) IE | NE | SSE | R{Ag⁺} | PE | IE (+), where IE is the inert electrode (graphite powder), NE is the negative electrode (silver powder), SSE is the solid-state electrolyte (glassy Ag₃GeS₃Br), PE is the positive electrode, R{Ag⁺} is the region of Ag⁺ diffusion into PE. The measured EMF and temperature values of ECs were used to determine the standard thermodynamic functions of the compounds Ag₃Ga₂S₄Br and Ag₂₇Ga₂S₁₂Br.

This study investigates the reaction behavior of high-rank coal with different particle sizes in the coal gasification and ironmaking polygeneration process. The gasification and ironmaking polygeneration process is promising for achieving CO₂ recycling and clean coal utilization. Thus, the CO₂ gasification behavior of two kinds of high-rank coal was investigated by the isothermal thermogravimetric method. The pore structure, chemical structure, and ash composition were also systematically tested. The results show that the particle size significantly influences the CO₂ gasification of high-rank coal. Smaller particle sizes exhibit enhanced reactivity and faster gasification kinetics due to increased surface area and improved accessibility to reactants. The chemical structure and ash can also affect the fuel gasification reactivity. The findings provide valuable insights into optimizing high-rank coal gasification to improve overall process performance and resource efficiency.

This study proposes the technology of using waste carbide slag to treat carbon dioxide in the tail gas of electrolytic aluminum and innovatively designs a Venturi gas–liquid–solid three-stage reactor. The ability of Ca(OH)₂ slurry to absorb CO₂ under operating conditions was studied. The results show that the residual proportion of CO₂ in the waste gas is below 0.08% through the absorption of the stage reactor. The particle size of calcium carbonate obtained from the third-stage reactor can reach 5.9 um, significantly smaller than the mixing tanks and industrial products. When the gas velocity is greater than 21.231 m/s, the gas holdup and bubbles rising velocity increases rapidly, so the superficial gas velocity should not exceed 21.231 m/s. As the superficial liquid velocity increases, the bubble rising velocity and gas holdup first increase and then decrease. The superficial liquid velocity should exceed 1.504 m/s. As the inlet gas pressure increases, the bubbles rising velocity first increases and then decreases, and the gas holdup first decreases and then increases. Therefore, the gas pressure should be greater than 0.15 MPa.