Direct Reduction Research Articles

Effect of Na<sub>2</sub>CO<sub>3</sub> and CaCO<sub>3</sub> on deep dephosphorization by the direct reduction of high-phosphorus oolitic hematite

The direct reduction–magnetic separation process based on coal is considered to be one of the most important methods that can effectively utilize high-phosphorus oolitic hematite. In this study, the mechanism of the effects of CaCO<sub>3</sub> and Na<sub>2</sub>CO<sub>3</sub> on the dephosphorization of high-phosphorus oolitic hematite during the direct reduction process was investigated using X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive spectrometer (EDS). The results showed that Na2CO3 and CaCO3 reacted with Al<sub>2</sub>O<sub>3</sub> and SiO<sub>2</sub> during the direct reduction process, inhibited the generation of hercunite (FeAl<sub>2</sub>O<sub>4</sub>) and fayalite (Fe<sub>2</sub>SiO<sub>4</sub>), and promoted the reduction of metallic iron (Fe). Furthermore, the reaction inhibited the reduction of apatite and prevented the generation of FeP<sub>2</sub>. Na<sub>2</sub>CO<sub>3</sub> could change the form of phosphorus in the gangue from Ca<sub>3</sub>(PO<sub>4</sub>)<sub>2</sub> to Na<sub>2</sub>Ca<sub>4</sub>(PO<sub>4</sub>)<sub>2</sub>SiO<sub>4</sub>. Increasing the dosages of Na2CO3 and CaCO3 in the dephosphorization agent and increasing the content of Na<sub>2</sub>CO<sub>3</sub> in the dephosphorization agent were beneficial to the growth of metallic iron particles, and increasing the dosage of Na<sub>2</sub>CO<sub>3</sub>, CaCO<sub>3</sub> in the dephosphorization agent had more significant effects on metallic iron particles than increasing the content of Na<sub>2</sub>CO<sub>3</sub> in the dephosphorization agent. The research conducted in this study is expected to provide a basis for the effective exploitation of complex and refractory iron ores.

Relationships among intensive blood pressure control, morning blood pressure surge and 24-hour blood pressure variability

Abstract Objectives This study aimed to investigate the relationships between cardiovascular outcomes and blood pressure (BP) reduction, 24-hour BP variability (BPV), morning BP surge (MBPS), and visit-to-visit BPV. Methods This study involved 897 participants from the Systolic Blood Pressure International Trial (SPRINT), for whom biochemical and demographic data, medication history, and various blood profile information were collected. Univariate and multivariate linear regression models were used to assess the impact of intensive BP management on 24-hour BPV and the MBPS. Results Among the 897 participants (average age 71.48 ± 9.42 years; 640 males), 453 received intensive treatment. Those in the intensive group were more likely to be on ACE inhibitors, CCBs, or diuretics. This group showed significant reductions in 24-hour systolic and diastolic BP, as well as in both short-term and long-term BPVs, such as average real variability (ARV) and MBPS. The analysis demonstrated strong associations between intensive BP management and improvements in various BPV measures, including systolic ARV, diastolic BP ARV, and cumulative BP loads. A significant correlation was also found between intensive BP lowering and the primary composite outcome of the SPRINT study. Conclusions This study highlighted the significant associations between intensive BP management and reductions in the MBPS and 24-hour BPV, which affect both short-term and long-term health outcomes. The primary benefits of intensive BP control appear to stem from direct BP reduction rather than changes in BPV. However, further extensive randomized controlled trials are needed to confirm these findings.

Solutions for Reducing Perioperative Supply Waste.

Health care costs continue to increase in the United States, and unused perioperative supplies can contribute to both these costs and increased waste. Reducing perioperative waste can decrease hospital costs and promote sustainability. Perioperative leaders can consider a variety of solutions to decrease unused perioperative supplies, including streamlining and standardizing surgical packs, implementing surgeon scorecards and a surgical receipt system, and updating surgeon preference cards. The available literature does not provide data on waste reduction for all listed solutions; however, these initiatives have had positive financial effects for hospitals through either direct cost reduction or cost avoidance. Although the cost of implementation may vary among hospitals, streamlining surgical packs (including custom packs) appears to be an effective solution with a lower cost than other strategies, and avoids the wasting of opened supplies that are not needed.

Prevalent and incident anemia in PARAGON-HF

Abstract Background Anemia is a common comorbidity in patients with heart failure (HF) and is associated with adverse prognosis. Renin-angiotensin system inhibitors (RASi) have been shown to lower hemoglobin levels, potentially related to direct reductions in erythropoetin levels and hematopoiesis. We examined whether sacubitril/valsartan might attenuate this effect of RASi alone on incident anemia in patients with HF with mildly reduced or preserved ejection fraction. Methods PARAGON-HF was a global, multicenter randomized clinical trial of sacubitril/valsartan versus the RASi valsartan in patients with HF and left ventricular ejection fraction≥45%. Anemia was defined as hemoglobin <120 g/L in women and <130 g/L in men. We evaluated changes in hemoglobin, risks of incident anemia and new oral iron initiation during follow-up. We also assessed treatment effects on the primary composite endpoint of total HF hospitalizations (HFH) and cardiovascular (CV) death according to anemia status. Results Among 4,795 participants with a hemoglobin measurement available, 1,111 (23.2%) had anemia at randomization of which 3.5%, 77.7%, and 18.8% were characterized as micro-, normo-, and macrocytic anemia. 5.6% were treated with oral iron at baseline. Over a 2.7-year median follow-up period, patients with anemia were at nearly twice the risk of the primary outcome (21.6 vs. 11.5 per 100py; rate ratio 1.90; 95% CI: 1.62-2.21; P<0.001). Compared with valsartan, sacubitril/valsartan significantly slowed the decline in hemoglobin levels by 1.4 g/L (95% CI: 0.4-2.4 g/L; P = 0.005; Figure 1 Panel A). Participants treated with sacubitril/valsartan were at significantly lower risk of developing anemia (30.3% vs. 37.6%; HR 0.76; 95% CI: 0.68-0.85; P<0.001; Figure 1 Panel B) and starting oral iron therapy (8.1% vs. 10.0%; HR 0.81; 95% CI: 0.67-0.97; P = 0.026; Figure 2). Treatment effects of sacubitril/valsartan vs. valsartan on the primary endpoint were consistent among patients with and without anemia (Pinteraction=1.00). Conclusions Among patients with HF with mildly reduced or preserved ejection fraction, treatment with sacubitril/valsartan resulted in slower declines in hemoglobin, lower rates of incident anemia, and fewer new initiations of iron therapy compared with RASi.

Optimization of Hydrogen Utilization and Process Efficiency in the Direct Reduction of Iron Oxide Pellets: A Comprehensive Analysis of Processing Parameters and Pellet Composition

The article deals with the H2 consumption for different processing conditions and the composition of the processed pellets during the direct reduction process. The experiments are carried out at 600–1300 °C, with gas pressures of 1–5 bar, gas flow rates of 1–5 L min−1, and basicity indices of 0 to 2.15. Pellets with different compositions of TiO2, Al2O3, CaO, and SiO2 are analyzed. The gas flow rate is crucial, with 0–10 L min−1 leading to an H2 consumption of 0–5.1 kg H2/kg pellet. The gas pressure (0–10 bar) increases the H2 consumption from 0 to 5.1 kg H2/kg pellet. Higher temperatures (600–1300 °C) reduce H2 consumption from 5.1 to 0 kg H2/kg pellet, most efficiently at 950–1050 °C, where it decreases from 0.22 to 0.10 kg H2/kg pellet. An increase in TiO2 content from 0% to 0.92% lowers H2 consumption from 0.22 to 0.10 kg H2/kg pellet, while a higher Fe content (61–67.5%) also reduces it. An increase in SiO2 content from 0% to 3% increases H2 consumption from 0 to 5.1 kg H2/kg pellet. Porosity structure influences H2 consumption, with the average pore size decreasing from 2.83 to 0.436 mm with increasing TiO2 content, suggesting that micropores increase H2 consumption and macropores decrease it.

Microbial fuel cells: A potent and sustainable solution for heavy metal removal

The global water pollution problem is becoming increasingly crucial. One of the major contributors to water pollution is the presence of heavy metals. Heavy metals pose significant threat to both humans and all ecosystems. Various factors influence the removal of heavy metals from wastewater, including pH, temperature, natural organic matter (NOM), and ionic strength, which vary based on the chemical properties of the pollutants. More effective and modern approaches receive attention and extensively researched to substitute traditional methods such as adsorption, membrane filtration, and chemical-based separation. Among these methods, Microbial fuel cells (MFCs) are particularly intriguing. This review article focuses on MFCs and their potential applications in various fields, including clean water production. MFCs represent an innovative technology that not only generates electricity, but also demonstrates significant potential for heavy metal removal from wastewater. Cathodic chamber of MFCs effectively reduces heavy metals, while organic substrates act as carbon and electron donors in the anodic chamber. Through various mechanisms, including direct and indirect metal reduction, biofilm formation (metal sequestering), electron shuttling, and synergistic interactions among microbial communities, microorganisms exhibit remarkable efficiency in removing metals. Studies showed that dual- and single-chamber MFCs could efficiently remove a range of heavy metals, including chromium, cobalt, copper, vanadium, mercury, gold, selenium, lead, magnesium, manganese, zinc, and sodium, while simultaneously generating electricity, achieving high removal efficiencies ranging from 25% to 99.95%. This range of efficiency varies depending on the specific contaminant being targeted, the concentration of the contaminant, as well as the operating conditions such as pH and temperature. Moreover, MFCs demonstrated a wide range of power outputs, typically ranging from 0.15 W/m² to 6.58 W/m², depending on the specific configuration and conditions. These findings underscore the potential of MFCs as a sustainable and efficient approach for both wastewater treatment and energy generation.

Regulating Local Electron Distribution of Cu Electrocatalyst via Boron Doping for Boosting Rapid Absorption and Conversion of Nitrate to Ammonia

AbstractThe electrochemical reduction of nitrate to ammonia (NO3RR) is an effective route to ammonia synthesis with the characteristics of low energy input. However, the complex multi‐electron/proton transfer pathways associated with this reaction may trigger the accumulation of competitive by‐products. Herein, boron (B)‐doped Cu electrode (denoted as B–Cu2O/Cu/CP) as “all‐in‐one” catalyst is prepared by one‐step electrodeposition strategy. Caused by the B doping, the charge redistribution and local coordination environment of Cu2O/Cu species are modulated, resulting in the exposure of active sites on the Cu2O/Cu/CP catalyst. In‐situ Fourier transform infrared spectroscopy and theoretical investigations demonstrate that both Cu2O and Cu sites modulated by B can effectively enhance the adsorption of NO3− and facilitate the conversion of intermediate by‐products, thus promoting the direct reduction of NO3− to NH3. Consequently, a remarkable Faradaic efficiency of 92.74% can be obtained on B–Cu2O/Cu/CP catalyst with minimal accumulation of by‐products. It is expected that this work, based on the heterogeneous B doping, will open a maneuverable and versatile way for the design of effective catalysts.

Calcium Carbonate as Dephosphorization Agent in Direct Reduction Roasting of High-Phosphorus Oolitic Iron Ore: Reaction Behavior, Iron Recovery, and Dephosphorization Mechanism

Calcium carbonate, renowned for its affordability and potent dephosphorization capabilities, finds widespread use as a dephosphorization agent in the direct reduction roasting of high-phosphorus oolitic hematite (HPOIO). However, its precise impact on iron recovery and the dephosphorization of iron minerals with phosphorus within HPOIO, particularly the mineral transformation rule and dephosphorization mechanism, remains inadequately understood. This study delves into the nuanced effects of calcium carbonate on iron recovery and dephosphorization through direct reduction roasting and magnetic separation. A direct reduction iron (DRI) boasting 95.57% iron content, 93.94% iron recovery, 0.08% phosphorus content, and an impressive 92.08% dephosphorization is achieved. This study underscores how the addition of calcium carbonate facilitates the generation of apatite from phosphorus in iron minerals and catalyzes the formation of gehlenite by reacting with silicon dioxide and alumina, inhibiting apatite reduction. Furthermore, it increases the liquid phase, enhancing the dissociation of metallic iron monomers during the grinding procedure, thus facilitating efficient dephosphorization.

Bisulfite enhances p-nitrophenol degradation by zero-valent iron under oxic conditions: Combination of indirect reduction by superoxide radical and direct reduction

Advanced oxidation processes based on the combination of zero-valent iron (ZVI) and S(IV) have been extensively investigated for oxidative degradation of organic pollutants, but little attention has been paid to their reducing capacities in the presence of oxygen. This work found bisulfite (BS) could greatly enhance the degradation of p-nitrophenol (PNP) by ZVI under oxic conditions and PNP was only reduced to p-aminophenol without further degradation. A combination of indirect reduction by superoxide radical (O2•–) and direct reduction by ZVI was verified as the mechanism of PNP degradation. Highly oxidizing species, such as hydroxyl radical (HO•) and sulfate radical (SO4•−), were also produced in the ZVI/BS system under oxic conditions but did not contribute to pollutant degradation perhaps due to the rapid consumption by reducing substances like BS ions and the released Fe2+. BS concentration, ZVI dosage, initial solution pH and coexisting anions (CO32–, PO43– and Cl–) affected the degradation of PNP. ZVI lost the reactivity after used for three times because of the production of goethite and lepidocrocite covered on its surface. This study will provide a new insight into degradation of organic pollutants in ZVI/BS system under oxic conditions.

Designing 1-nm-Thick MOF Nanosheets with Donor-Acceptor Complexes for Photosynthesis of H2O2 Using Water and Dioxygen Only.

Artificial photosynthesis of hydrogen peroxide (H2O2) presents a promising environmentally friendly alternative to the industrial anthraquinone process. This work designed ultrathin metal-organic framework (MOF) nanosheets on which porphyrin ligand as an electron donor (D) and anthraquinone (AQ) as an electron acceptor (A) are integrated as the D-A complexes. The porphyrin component allows the MOF nanosheets to absorb full-spectrum solar light while the acceptor AQ motif promotes central aluminum ion coordination, hindering layer stacking to achieve a thickness of 1.0 nm. The ultrathin D-A design facilitates the separation of electrons from the MOF skeleton to the AQ motif, which induces the direct two-electron oxygen reduction reaction (ORR) mediated by the reversible redox couple of AQ-AQH2 and multielectron water oxidation reaction (WOR) driven by holes remaining on the porphyrin part. In O2-saturated water, the ultrathin MOF nanosheets outperformed the AQ-free bulk and multilayered counterparts by 2.9 and 2.6 times in H2O2 production, respectively, achieving the apparent quantum yield of 4.8% at 420 nm. It also surpasses other benchmark photocatalysts, including the typical MOF photocatalyst, MIL-125-NH2, and organic polymeric photocatalysts. The ultrathin D-A MOF photocatalyst generated H2O2 via both two-electron ORR as a major path and two-electron WOR as a minor path. This approach presents a promising strategy for the rational design of efficient nanostructured photocatalysts for solar fuels and chemicals.

Preparation of Oxidized Pellets of Vanadium Titanium Magnetite and Direct Reduction Behavior in Hydrogen‐Based Shaft Furnace

Herein, the optimized process parameters for the preparation of vanadium‐titanium magnetite (VTM) pellets are determined, and an efficient and green utilization technology for VTM based on the integration of oxidation roasting‐hydrogen‐based shaft furnace direct reduction is established. The results indicate that the preferable VTM oxidized and pre‐reduced pellets can be prepared by preheating at 925 °C for 18 min and roasting at 1200 °C for 25 min, followed by the reduction temperature of 1050 °C at the reduction atmosphere of 4% CO2 and H2/CO = 8. The corresponding compressive strength of the preheated and roasted pellets is 516 N per pellet and 2028 N per pellet, respectively. In addition, the LTD+6.3 and LTDUP of roasted pellets are 80.86% and 93.90%, and the corresponding reducibility index, reduction swelling index, and the reduction sticking index are 0.0428, 2.32%, and 2.50%, respectively. All of which meet the production requirements of hydrogen‐based shaft furnace.

Mechanism of Directional Reduction Strengthening of Nickel Laterite Ore Under Fluidization Condition

Mechanism of Directional Reduction Strengthening of Nickel Laterite Ore Under Fluidization Condition

Evaluation of Some Uncertainties in the Modeling of Blast Furnace Hydrogen Injection

While blast furnaces remain the dominant ironmaking technology, there is growing interest in using hydrogen to partially replace coke and pulverized coal to reduce CO2 emissions in this hard‐to‐decarbonize process. However, significant discrepancies in modeling the tuyere injection of hydrogen are noted in the literature, which can challenge the scale‐up from modeling predictions and pilot trials to actual blast furnace operations. To address this, the impact of uncertainties in the assumptions of the temperature in the thermal reserve zone and the ratio of H2 and CO utilization on the results of blast furnace process modeling are evaluated using a 1D steady‐state zonal model. The study indicates that variations in the assumed value of thermal reserve zone temperature significantly impact the estimation of optimal hydrogen injection rate, coke replacement ratio, and direct CO2 emissions reductions. In contrast, the same parameters are much less affected by the variations in the assumed value of the proportion between H2 and CO utilization ratios, which, however, affect the top gas composition. A need for further research to determine the range of the difference in temperatures of gas and solid in the thermal reserve zone tolerable for smooth blast furnace operation is highlighted.

Experiences of patients with hard-to-heal wounds: insights from a pilot survey.

To learn about the experiences of people who seek treatment for hard-to-heal wounds, we distributed a nationwide pilot survey, asking questions about the nature of their wound, how it shaped their daily lives, pathways to receiving care and experiences with treatment. The long-term objective is to quantify the journey of patients with hard-to-heal wounds to identify ideal intervention points that will lead to the best outcomes. This article summarises the findings, implications, limitations and suggestions for future research. Qualitative data were self-reported from patients with hard-to-heal wounds (open for ≥4 weeks) in a pilot chatbot survey, (Wound Expert Survey (WES)) provided online in the US on Meta platforms (Facebook and Instagram) between 2021 and 2022. The US national pilot survey attracted responses from 780 patients, 27 of whom provided a video testimonial. Some 57% of patients delayed treatment because they believed their wound would heal on its own, and only 4% saw a wound care specialist. Respondents reported the cost of care as the most frequent reason for not following all of a doctor's treatment recommendations. Queries regarding quality of life (QoL) revealed that more than half (65%) said they have negative thoughts associated with their wound at least every few days. Some 19% of respondents said their wound had an odour and, of them, 34% said odour had a major or severe negative impact on their self-confidence. Economically, nearly one-quarter of respondents said having a wound led to a drop in their total household income and 17% said their wound led to a change in their employment status. A national pilot survey of patients with hard-to-heal wounds revealed that many delay seeking professional assistance and only a small minority see a wound care specialist. Experiencing an ulcer, even for a few months, can have significant negative effects on a patient's QoL. Patients frequently had negative thoughts associated with their wound, and odour compounded these negative effects, leading to major or severe negative impacts on self-confidence. Households experienced a decline in income, due to both the direct reduction or loss of patient employment and the additional time spent by family members assisting in patient recovery. Thus, a variety of factors contribute to poor outcomes for patients with hard-to-heal wounds. To validate and extend these preliminary results, future surveys of patients with hard-to-heal wounds should focus on additional reasons patients do not seek professional help sooner. To improve health outcomes and QoL, assessment of patient socioeconomic variables should occur whenever wound closure stalls.

Boosted direct electrochemical reduction of As(III) from arsenic wastewater via Cu(II)-assisted codeposition on a CuIn alloy electrode

Arsenic contamination is a severe environmental problem. A promising strategy for addressing this issue is the direct conversion of highly toxic As(III) to less toxic elemental arsenic (As(0)) using electrochemical reduction technology. In this study, a novel CuIn alloy nanoparticles-modified copper foam (CuIn NPs/CF) was prepared as an efficient cathode for the electrocatalytic reduction of highly mobile As(III) to solid As(0). Density functional theory (DFT) results revealed that the Cu-In bimetallic system exhibited weaker H atom bonding, and the Cu-ln surface was more favorable for the adsorption of *AsO₃ species than the Cu surface. Compared to the pristine CF electrode, CuIn NPs/CF was demonstrated to effectively suppressed the hydrogen evolution reaction with an enlarged hydrogen evolution potential of 1.45 V, and displayed a superior As(0) recovery yield. The conversion of As(III) to As(0) was further enhanced by adding Cu²⁺ to the electrolyte, facilitating a Cu-As co-deposition process. Notably, the CuIn NPs/CF electrode achieved an As(0) recovery yield of 5.38 mg cm⁻² after eight successive recycling tests. This work not only presents a green and sustainable strategy for As(III) removal, but also provides valuable insights into the rational design of Cu-based alloy cathodes for electrocatalytic reduction.

Development and application of carbon dioxide direct mineralization technology and emission reduction device

Abstract This study analyzes the principles and methods of carbon dioxide mineralization fixation to address the challenges posed by global climate and ecological changes, achieve carbon neutrality goals, and solve carbon utilization issues in the development of the fluorosilicon new material industry. The research focuses on the direct mineralization reaction system of carbon dioxide flue gas and the development of a carbon dioxide emission reduction device utilizing wet mineralized gas treatment technology. To implement alkaline waste management for industrial solid waste. The research shows that the wet carbon dioxide mineralization and emission reduction device can make the alkaline solution better mineralize carbon dioxide, avoid the gas discharge too fast and affect the reaction rate. At the same time, the solution is mixed and the exhaust linkage is carried out to further improve the reaction rate, and provide a reference for the development of large-scale carbon dioxide utilization technology suitable for high energy consumption industries.

Fungal degradation of phenylacetate focusing on CRISPR/Cas9-assisted characterization of two oxidative enzyme genes of Akanthomyces muscarius AM1091

The degradation of phenylacetate (PA) was investigated as a model to explore aromatic compound breakdown in the fungal system. Fungal strains capable of utilizing PA as their sole carbon source were isolated using a minimal solid medium supplemented with 0.5 % PA. Subsequent cultivation in minimum liquid medium revealed that selected fungal strains, including Trametes versicolor TV0876 and TV3295, Paecilomyces hepiali PH4477, and Akanthomyces muscarius AM1091, efficiently removed PA within 24 h. HPLC analysis of culture supernatants from various fungal strains revealed a time-dependent accumulation of 2-hydroxyphenylacetate (2-HPA) and 4-hydroxyphenylacetate (4-HPA), two key major metabolic products primarily found in ascomycetes and basidiomycetes, respectively. This suggests that the first hydroxylation of PA is catalyzed by two distinct hydroxylases, one for each fungal group. Furthermore, fungal species that make 4-HPA also produce phenylethanol (PE), indicating a distinct catabolic mechanism to remove PA by direct reduction of PA to PE. A. muscarius AM1091, identified as the most efficient PA degrader in this study, was studied further to determine the biochemical pathway of PA degradation. RNA-Seq and RT-PCR analyses of AM1091 revealed two oxidative enzyme genes, CYP1 and DIO4, upregulated in the presence of PA. Targeted disruption utilizing preassembled Cas9-gRNA ribonucleoprotein complexes and homologous DNAs harboring the URA3 gene as an auxotrophic marker resulted in the cyp1 and dio4 mutant strains. The cyp1 mutant was incapable of converting PA to 2-HPA, indicating its involvement in the C2 hydroxylation, whereas the dio4 mutant was unable to degrade 2,5-dihydroxyphenylacetate (2,5-DHPA), resulting in the accumulation of 2,5-DHPA. Our findings indicate that A. muscarius AM1091 degrades PA through the activities of CYP1 and DIO4 for the C2 hydroxylation and subsequent ring-opening reactions, respectively.

Stay with the green: New insights into ancient copper smelting in the Tonglüshan site, China

This paper presents new archaeometallurgical analyses from the Tonglüshan site, a famous ancient mining and smelting site in China. Results show that the primary phases in slag samples from two sites (Sifangtang and Lujia’nao) are all of a vitreous matrix, interspersed with fayalite crystals, wüstite, and hercynite. The trapped metallic particles in the slag are mainly raw copper with few sulfides present, which indicates a direct reduction process of oxidic ore. Iron-rich minerals were likely to be added as flux implied by the few unreacted inclusions in the slag samples. The extremely low copper content in the slag samples demonstrates a high rate of copper recovery, indicating that the copper smelting technology in the region had reached a considerably advanced level. In the meantime, the variations in metal content in slag samples from different periods reveal the diachronic changes in this copper smelting technology. The Tonglüshan site, with its millennia of ancient mining and metallurgical activities, provides an excellent material base for detailed studies on technological evolution.

High-value terminal treatment: Utilizing copper slag heat in the manufacture of copper-containing weathering steel

Copper slag, a bulk non-ferrous solid waste, is critical in establishing a closed-loop cycle in the copper metallurgy industry. Currently, the processing techniques for copper slag are characterized by prolonged procedures, secondary waste discharge, limited value utilization, and high energy consumption. A novel approach was proposed to harness the thermal energy inherent in molten copper slag for producing copper-bearing weathering steel and cement while simultaneously synergistically recovering lead and zinc. The results indicate that under the conditions of smelting temperature of 1500 °C, alkalinity of 1.06, smelting time of 60 min, and mechanical stirring, the recovery rates of copper, iron, lead, and zinc in copper slag reached 98.83%, 99.59%, 97.45%, and 98.51%, respectively. Furthermore, the feasibility of this approach was validated by laboratory-scale preparation of Q355GNH-grade copper-bearing weathering steel and S95-grade cement clinker. Computational analysis for the direct carbothermal reduction of molten copper slag in its thermal state reveals that, compared to the traditional flotation process, this approach saved 1177 MJ of thermal energy per metric ton of copper slag, equivalent to a reduction of 147 kg of carbon dioxide emissions. This study facilitates the zero-waste, high-value, and sustainable development of the copper smelting industry.

Pathways for decarbonizing China's iron and steel industry using cost-effective mitigation technologies: An integrated analysis with top-down and bottom-up models

The iron and steel industry (ISI), the second largest carbon emitter, produces 16 % of China's CO2 emissions, and its decarbonization will therefore play an important role in achieving the goal of carbon neutrality. This study identifies underlying low-carbon transition pathways of the ISI towards 2050, through investigating macro-level mitigation policies and technological advances. An integrated assessment model that integrates a top-down CGE method and a bottom-up objective planning method was constructed. The results show that the combination of mitigation policies and technological measures would substantially reduce CO2 emissions in the ISI, with the remaining 140 Mt to 520 Mt by 2050. Carbon mitigation in ISI in the short term mainly benefits from the technology retrofitting, the reduction of steel demand, which accounts for 17.8 % and 32.1 %, respectively. Breakthrough technologies of scrap-based electric arc furnace (EAF), hydrogen-based direct reduction (HDR-EAF) and carbon capture and storge (CCS), would play a fundamental role in reducing the CO2 emissions especially after 2030, contributing to 32.1 %, 16.0 % and 13.8 % of emission reduction, respectively. Of the 41-technologies assessed, 8-key technologies jointly mitigate over 55 % of CO2 emissions. The cost-effectiveness and mitigation potential of technologies would provide reference to policymaker for the mitigation in China's ISI.