Metallic Iron Research Articles

Marine eutrophication within the Tarim Platform in sync with Middle to Late Ordovician climatic cooling

Previous work has proposed climatic cooling and atmosphere–ocean oxygenation as potential triggers for the Great Ordovician Biodiversification Event, with the suggestion of better oxygenated oceans during the Middle to Late Ordovician. However, recent studies have argued for spatial and temporal heterogeneity in marine redox state on several continents. Here we investigate a black-shale succession accumulated within the Tarim Platform via a combination of geochemical proxies to address these debates. Negative shifts in bulk nitrogen isotopes and synchronous increases in excess phosphorus suggest moderate-high marine primary production coinciding with the development of bottom-water anoxia, as indicated by enrichments in highly reactive iron and modest concentrations of redox-sensitive trace metals (Mo, U). Moreover, the occurrence of black shale correlates well with equivalent successions formed in deep-water marginal basins along several continents, including South China, North China, Laurentia and Baltica. This may suggest an expansion of marine anoxia in low-latitude zones of the late Darriwilian to early Sandbian oceans, probably as a result of enhanced upwelling in sync with climatic cooling. The extent and ultimate cause of marine anoxia requires further quantifying constraints at a global scale, which will enable potential links between global oceanic redox conditions and concurrent biotic changes to be evaluated in more detail. Supplementary material: Geochemical dataset for the Dawangou section (Table S1) is available at https://doi.org/10.6084/m9.figshare.c.7036552 Thematic collection: This article is part of the Chemical Evolution of the Mid-Paleozoic Earth System and Biotic Response collection available at: https://www.lyellcollection.org/topic/collections/chemical-evolution-of-the-mid-paleozoic-earth-system

On the formation of dendritic iron from alkaline electrochemical reduction of iron oxide prepared for metal fuel applications

Low-temperature electrochemical reduction (electroreduction) of iron oxides is a promising alternative to the conventional methods for iron production due to its CO2-free operation and relatively low energy consumption. In this work, we demonstrate a novel approach for electrochemical iron production by promoting the formation of dendritic structures during iron electrodeposition, which facilitates the easy harvesting of deposits in powder form. Experiments were conducted using a single pair of parallel plate electrodes, immersed in a mixture of hematite (Fe2O3) powder and aqueous alkaline (NaOH) slurry. The effects of current density, Fe2O3 mass fraction, temperature, and powder size on current efficiency and deposit morphology are investigated. A large quantity of dendritic iron structures is observed when experiments are carried out without stirring and/or applying heat from a heating plate. This condition suggests temperature and (ion/species) concentration gradients in the system. The dendrites are mainly deposited on the cathode's sides, corners, and edges. Different deposits and dendritic structures (compact layer deposit, moss-like deposit, deposit with whisker-like dendrites, and deposit with crystal-like dendrites) are observed as operating conditions change. Overall, a cathodic deposition of metallic iron with a high Faradaic efficiency (≥90 %) is successfully accomplished. The present findings provide new insights into the production of electrolytic iron powder and its future use as a carbon neutral and sustainable fuel/energy carrier.

Treatment of acidic electroplating effluent from small scale industries using batch and continuous flow adsorption reactor

If electroplating effluent discharges aren’t properly treated, they have a detrimental effect on the aquatic ecology. The effluent characteristics comprise heavy metals that were toxic and causes carcinogenic effects. Among the conventional methods, adsorption being the most economically viable and technically straightforward. This study focuses on the removal of hexavalent chromium ion from the electroplating effluent using commercial activated carbon in both batch and continuous flow experiments. In column studies, various grades of commercial activated carbon were tested, with 80 × 200 mesh size yields complete Cr6+ removal. The batch study revealed that 83% removal was achieved at 5g of 80 × 200 mesh size activated carbon. The isotherm studies indicated a better fit with the Langmuir model and kinetics studies indicated pseudo-second order kinetics. Continuous flow experiments with an 80 × 200 mesh size activated carbon bed showed an upward trend in pH. However, Cr6+ removal efficiency decreased over time. UV–vis spectroscopy using the Diphenyl carbazide method confirmed Cr6+ concentrations. Morphological and elemental analyses were conducted using SEM and Edax, revealing significant changes before and after treatment. These findings underscore the effectiveness of activated carbon in mitigating the environmental impact of electroplating effluents, particularly in Cr6+ removal.

Ultrasound assisted fabrication of the yeast protein-chitooligosaccharide-betanin composite for stabilization of betanin

Betanin, a water-soluble colorant, is sensitive to light and temperature and is easily faded and inactivated. This study investigated the formation of yeast protein-chitooligosaccharide-betanin complex (YCB) induced by ultrasound treatment, and evaluated its protective effect on the colorant betanin. Ultrasound (200–600 W) increased the surface hydrophobicity and solubility of yeast protein, and influenced the protein’s secondary structure by decreasing the α-helix content and increasing the contents of β-sheet and random coil. The ultrasound treatment (200 W, 15 min) facilitated binding of chitooligosaccharide and betanin to the protein, with the binding numbers of 4.26 ± 0.51 and 0.61 ± 0.06, and the binding constant of (2.73 ± 0.25) × 105 M−1 and (3.92 ± 0.10) × 104 M−1, respectively. YCB could remain the typical color of betanin, and led to a smaller and disordered granule morphology. Moreover, YCB exhibited enhanced thermal-, light-, and metal irons (ferric and copper ions) -stabilities of betanin, protected the betanin against color fading, and realized a controlled release in simulated gastrointestinal tract. This study extends the potential application of the fungal proteins for stabilizing bioactive molecules.

Mechanism of solid-state diffusion reaction in vacuum between metal (Fe, Ni, and Co) and 4H–SiC

Experiments were conducted to investigate the vacuum diffusion reactions between 4H–SiC and various metals (iron (Fe), nickel (Ni), and cobalt (Co)). The effects of temperature, time, and metallic materials on the diffusion reactions were systematically analyzed. Notably, a solid-state diffusion reaction between the metal and 4H–SiC was observed at low temperatures, and the mechanism governing the solid-state interface diffusion reaction between the single-crystal 4H–SiC and metals was elucidated. The results indicate that a chemical reaction occurs between the metal and 4H–SiC during solid-state diffusion, leading to the formation of metal silicides under vacuum conditions. The temperature threshold for the solid-state diffusion reaction between 4H–SiC and metals falls within the range of 550–650 °C. Interestingly, the diffusion reaction proceeds without soaking. Furthermore, the metal type significantly influenced the diffusion rate.

Adsorption and desorption mechanism of toluene gas by iron modified activated carbon fiber

To enhance the adsorption performance of activated carbon fiber (ACF) on volatile organic compounds such as toluene, a series of Fex/ACF adsorption materials were prepared by impregnation and anaerobic atmosphere calcination. The various adsorption effects of Fex/ACF on toluene under different synthesis conditions were discussed, and both the modified and unmodified adsorption materials were characterized by using N2 adsorption–desorption isotherms, XRF, XRD, FT-IR, SEM, and XPS etc methods. The results indicated that iron modified ACF demonstrated the optimal adsorption performance when ACF was loaded with 3 % iron and calcined at 500 °C, and it achieved a saturated toluene adsorption capacity of 218.12 mg/g, which was 24 % higher than that of the unmodified sample. And its adsorption process of toluene followed Yoon-Nelson model. The adsorption capacity was maintained at approximately 70 % when four adsorption/desorption cycle tests. The toluene adsorption performance of Fe0.03/ACF-500 on toluene mainly involved surface adsorption (such as n-π interaction, and π-π interaction), pore filling, and complexation between the loaded metal iron and toluene.

Associations of multiple metal intake with all-cause and cardiovascular mortality in US adults stratified by age and sex: A prospective cohort from the NHANES database study

Aim and objectivesThe relationship between dietary metal intake and mortality risk is controversial, and we investigated the relationship between intake of five metals (iron, copper, selenium, zinc, and magnesium) and all-cause, cardiovascular mortality in the total population, gender subgroups, and age subgroups. Materials and methods17,207 participants from the National Health and Nutrition Examination Survey (NHANES) database from 2009 to 2016 were included in this study. Kaplan-Meier survival curves, multivariate Cox proportional hazards models, and restrictive cubic spline (RCS) curves were used to explore the association between metal intake and all-cause, cardiovascular mortality. ResultsIn this study, the average dietary metal intake of men and older people was lower than that of women and younger people. The RCS curves found in the whole population that all-cause mortality was negative linearly associated with copper intakes, L-shaped with zinc and magnesium intakes. Further subgroup analyses of copper, zinc, and magnesium by age and gender revealed that only magnesium showed statistically significant differences in the age subgroups. In the 20–40 population, there was a non-linear increasing trend in magnesium intake and all-cause mortality, whereas there was a non-linear decreasing trend in the > 60 population. ConclusionThe relationship between metal intake and mortality is more than a simple linear correlation, and differences in age can affect this correlation. In metal exposure studies, different populations can be studied to better determine the effect of metal exposure on mortality. Data AvailabilityThe dataset used for statistical analysis in this study is available on the NHANES website: https://www.cdc.gov/nchs/nhanes/index.htm.

Case study of chemical and enzymatic degumming processes in soybean oil production at an industrial plant

The vegetable oil degumming process plays a critical role in refining edible oil. Phospholipids (PL) removal from crude extracted soybean oil (SBO) by the enzymatic degumming process has been investigated in this work. Enzymatic degumming of extracted SBO with microbial phospholipase A1 PLA-1 Quara LowP and Lecitase Ultra enzymes have also been studied comparatively. The main novelty of our work is the use of the enzymatic degumming process on an industrial scale (600 tons a day). Many parameters have been discussed to understand in detail the factors affecting oil losses during the degumming process. The factors such as chemical conditioning (CC) by phosphoric acid 85%, the enzyme dosage mg/kg (feedstock dependent), the enzymatic degumming reaction time, and the characteristics of the plant-processed SBO have been discussed in detail. As a main point, the degummed oil with a phosphorus content of < 10 mg/kg increases yield. Quara LowP and Lecitase Ultra enzymes are not specific for certain phospholipids PL; however, the conversion rate depends on the SBO phospholipid composition. After 4 h, over 99% of Phospholipids were degraded to their lysophospholipid LPL (lysolecithin). The results showed a significant effect of operating parameters and characteristics of different origins of SBO, fatty acids FFA content, Phosphorus content and total divalent metals (Calcium Ca, Magnesium Mg and Iron Fe mg/kg) content on the oil loss. The benefit of using enzymatic degumming of vegetable oils rather than traditional chemical refining is that the enzymatic degumming process reduces total oil loss. This decrease is known as enzymatic yield. The enzymatic degumming also decreases wastewater and used chemicals and running costs; moreover, it enables physical refining by lowering the residue phosphorus to < 10 mg/kg.

Agro-Waste Sweet Pepper Extract-Magnetic Iron Oxide Nanoparticles for Antioxidant Enrichment and Sustainable Nanopackaging.

This study synthesizes magnetic iron oxide nanoparticles from agro-waste sweet pepper extract, exploring their potential as antioxidant additives and in food preservation. Iron (III) chloride hexahydrate is the precursor, with sweet pepper extract as both a reducing and capping agent at pH 7.5. Characterization techniques, including microscopy and spectroscopy, analyze the sweet pepper extract-magnetic iron oxide nanoparticles. Antioxidant capacities against 2,2-diphenyl-1-picrylhydrazyl are assessed, incorporating nanoparticles into banana-based bioplastic for grape preservation. Microscopy reveals cubic and quasi-spherical structures, and spectroscopy confirms functional groups, including Fe-O bonds. X-ray diffraction identifies cubic and monoclinic magnetite with a monoclinic hematite presence. Sweet pepper extract exhibits 100% inhibitory activity in 20 min, while sweet pepper extract-magnetic iron oxide nanoparticles show an IC50 of 128.1 µg/mL. Furthermore, these nanoparticles, stabilized with banana-based bioplastic, effectively preserve grapes, resulting in a 27.4% lower weight loss rate after 144 h compared to the control group (34.6%). This pioneering study encourages institutional research into the natural antioxidant properties of agro-waste sweet pepper combined with magnetic iron and other metal oxide nanoparticles, offering sustainable solutions for nanopackaging and food preservation. Current research focuses on refining experimental parameters and investigating diverse applications for sweet pepper extract-magnetic iron oxide nanoparticles in varied contexts.

Linearly Interlinked Fe-Nx -Fe Single Atoms Catalyze High-Rate Sodium-Sulfur Batteries.

Linearly interlinked single atoms offer unprecedented physiochemical properties, but their synthesis for practical applications still poses significant challenges. Herein, linearly interlinked iron single-atom catalysts that are loaded onto interconnected carbon channels as cathodic sulfur hosts for room-temperature sodium-sulfur batteries are presented. The interlinked iron single-atom exhibits unique metallic iron bonds that facilitate the transfer of electrons to the sulfur cathode, thereby accelerating the reaction kinetics. Additionally, the columnated and interlinked carbon channels ensure rapid Na+ diffusion kinetics to support high-rate battery reactions. By combining the iron atomic chains and the topological carbon channels, the resulting sulfur cathodes demonstrate effective high-rate conversion performance while maintaining excellent stability. Remarkably, even after 5000 cycles at a current density of 10 A g-1 , the Na-S battery retains a capacity of 325 mAh g-1 . This work can open a new avenue in the design of catalysts and carbon ionic channels, paving the way to achieve sustainable and high-performance energy devices.

Pre-treatment through reductive calcination for CO2 mineralization and selective battery metal extraction from laterites

The world needs an increasing supply of nickel and cobalt production as battery materials for sustainable development. However, the complexity of laterite deposits and the need to control CO2 emissions challenge the enhanced global supply from laterites. This work investigates the effects of calcination as a pre-treatment for selective battery metal extraction from both limonite laterite and saprolite laterite together with concurrent achievement of CO2 mineralization. Calcination under a reducing atmosphere of CO-N2 or CO-CO2 gas mixtures can significantly enhance the extraction of critical metals from both limonite and saprolite laterites. With calcination, the hydrated silicate minerals and ferric oxides converted to reactive olivine and ferrous oxide. The calcines thus can participate in the CO2 mineralization process to stabilize CO2 as mineral carbonates and release nickel and cobalt arising from the CO2 mineral carbonation into solution as complex ions with a ligand (such as sodium nitrilotriacetate, NTA). The optimum calcination conditions are 20 ∼ 30 % CO in CO-CO2 gas mixture at 700 °C. Beyond the optimum range results in the inadequate conversion of ferric to ferrous at too low CO concentration or over calcination of ferric to metallic iron at too high CO concentration. At the optimum conditions, the nickel & cobalt extraction and CO2 mineralization can reach 90 %, 93 %, and 39 % from laterite. Each tonne saprolite with the pre-treatment of calcination can recover 20.5 kg nickel, 0.59 kg cobalt, and simultaneously sequester 142 kg CO2 as stable mineral carbonates. The pre-treatment through slightly reductive calcination enables the robust suitability of the developed process for all layers of laterites for both critical battery metal recovery and carbon mineralization.

Mechanism of iron grains aggregation and growth in metalized pellet under the alternating magnetic fields

The direct reduction-magnetic separation method is highly efficient for producing metallic iron powder from low-grade complex ore resources. However, the limitation lies in the small average size of iron grains, which impedes the subsequent separation between metallic iron and gangue minerals. To address this, a novel method utilizing induction heating was introduced to stimulate the aggregation and growth of iron grains. Our study systematically investigated the growth kinetics behavior of iron grains under alternating magnetic fields. Additionally, we compared the impact of induction heating versus conventional heating on iron grain growth and delved into the mechanism through which the magnetic effect enhances the aggregation and migration of iron grains. The results indicate that iron grains can effectively aggregate and migrate to the edges of cracks or pellet surface under alternating magnetic fields, realizing the increase of average iron grain size and the pre-separation of metallic iron from gangue minerals. Specifically, the average iron grain size increased from 12.95 μm to 36.58 μm when induction heating temperature at 1300 °C for 100 min. Additionally, the total iron grade of concentrate reached 94.60% with ball milling 30 min and magnetic field intensity of 750 Gs. Finally, the growth model of iron grains under alternating magnetic fields was established and the mechanism of magnetic effect on promoting iron grains growth was revealed.

Photooxidation driven formation of Fe-Au linked ferrocene-based single-molecule junctions

Metal-metal contacts, though not yet widely realized, may provide exciting opportunities to serve as tunable and functional interfaces in single-molecule devices. One of the simplest components which might facilitate such binding interactions is the ferrocene group. Notably, direct bonds between the ferrocene iron center and metals such as Pd or Co have been demonstrated in molecular complexes comprising coordinating ligands attached to the cyclopentadienyl rings. Here, we demonstrate that ferrocene-based single-molecule devices with Fe-Au interfacial contact geometries form at room temperature in the absence of supporting coordinating ligands. Applying a photoredox reaction, we propose that ferrocene only functions effectively as a contact group when oxidized, binding to gold through a formal Fe3+ center. This observation is further supported by a series of control measurements and density functional theory calculations. Our findings extend the scope of junction contact chemistries beyond those involving main group elements, lay the foundation for light switchable ferrocene-based single-molecule devices, and highlight new potential mechanistic function(s) of unsubstituted ferrocenium groups in synthetic processes.

Reductive behavior of nickel and iron metallization in magnesian siliceous nickel laterite ores under the action of sulfur-bearing natural gas

Abstract This study is a process for the preparation of advanced nickel–iron alloys by selective reduction of nickel-poor laterite ores using a variety of reducing agents. The first part of the experiment was the reduction of nickel laterite ore using natural gas; the reduction yielded mostly nickel metal and a small amount of iron forming fine nickel–iron particles. Fine nickel–iron particles are formed through the reduction of nickel and a small amount of iron oxides. These particles are dispersed and embedded within silicates. Additionally, H2S present in natural gas reacts with iron oxide, resulting in the formation of FeS. This, in turn, forms a low melting point eutectic with Fe, which reduces surface tension and promotes the growth and aggregation of nickel–iron particles. This study aimed to investigate the effects of various parameters such as roasting temperature, roasting time, natural gas concentration, and nickel laterite pellet on the formation and aggregation of ferronickel particles in low-grade nickel laterite ores. The results showed that the optimum reduction parameters were achieved at 900°C, 120 min, 40% natural gas concentration, and 40–60 mesh nickel laterite size, with roasting temperature being the most important factor followed by natural gas concentration, roasting time, and nickel laterite pellet. Using these parameters, the metallization rates of Ni and Fe were found to be as high as 95.3 and 8.5%, respectively.

Ferrocene-Boosted Nickel Sulfide Nanoarchitecture for Enhanced Alkaline Water Splitting.

Enhanced electrocatalysts that are cost-effective, durable, and derived from abundant resources are imperative for developing efficient and sustainable electrochemical water-splitting systems to produce hydrogen. Therefore, the design and development of non-noble-based catalysts with more environmentally sustainable alternatives in efficient alkaline electrolyzers are important. This work reports ferrocene (Fc)-incorporated nickel sulfide nanostructured electrocatalysts (Fc-NiS) using a one-step facile solvothermal method for water-splitting reactions. Fc-NiS exhibited exceptional electrocatalytic activity under highly alkaline conditions, evident from its peak current density of 345 mA cm-2, surpassing the 153 mA cm-2 achieved by the pristine nickel sulfide (NiS) catalysts. Introducing ferrocene enhances electrical conductivity and facilitates charge transfer during water-splitting reactions, owing to the inclusion of iron metal. Fc-NiS exhibits a very small overpotential of 290 mV at 10 mA cm-2 and a Tafel slope of 50.46 mV dec-1, indicating its superior charge transfer characteristics for the three-electron transfer process involved in water splitting. This outstanding electrocatalytic performance is due to the synergistic effects embedded within the nanoscale architecture of Fc-NiS. Furthermore, the Fc-NiS catalyst also shows a stable response for the water-splitting reactions. It maintains a steady current density with an 87% retention rate for 25 hours of continuous operation, indicating its robustness and potential for prolonged electrolysis processes.

Chemometric and ICP-OES analyses of Forsythia europaea Degen &amp; Bald. and its extracts

Forsythia represents a group of plants originating mainly from China and Japan, but one species is endemic and grows in the Balkans (Balkan forsythia, Forsythia europaea Degen &amp; Bald.). Our previous studies on polyphenols in investigated extracts of Balkan forsythia showed that this plant is a good source of polyphenols. Analysis of the various extracts of Balkan forsythia (Forsythia europaea Degen &amp; Bald.) by the application of ICP-OES method showed that they are rich in different macro and microelements. The abundance order of macroelements is K&gt;Ca&gt;P&gt;Mg&gt;Na in all extracts. Among the transition metals iron, manganese, zinc and copper are particularly important, and the order of abundance is Zn&gt;Fe&gt;Cu&gt;Mn. Heavy metals which are the most frequent contaminants of food are lead, cadmium and arsenic, and the determination of their contents is of special importance on the safe use of plant species. The determination shows that aqueous extracts contain the highest quantity of elements, which is especially important. The contents of toxic elements are significantly lower than the permitted values. Statistical methods (Principal Component Analysis (PCA) and Agglomerative Hierarchical Clustering (AHC)) are useful tools for the grouping of samples and determining relations between investigated elements. This analysis shows that when higher quantities of Cr and Ba are present, the lower quantities of V are present, and vice versa. Based on our studies on polyphenols and minerals, we can expect the anti-inflammatory effects of extracts of Balkan forsythia.

Iron “ore” nothing: benthic iron fluxes from the oxygen-deficient Santa Barbara Basin enhance phytoplankton productivity in surface waters

Abstract. The trace metal iron (Fe) is an essential micronutrient that controls phytoplankton productivity, which subsequently affects organic matter cycling with feedback on the cycling of macronutrients. Along the continental margin of the US West Coast, high benthic Fe release has been documented, in particular from deep anoxic basins in the Southern California Borderland. However, the influence of this Fe release on surface primary production remains poorly understood. In the present study from the Santa Barbara Basin, in situ benthic Fe fluxes were determined along a transect from shallow to deep sites in the basin. Fluxes ranged between 0.23 and 4.9 mmol m−2 d−1, representing some of the highest benthic Fe fluxes reported to date. To investigate the influence of benthic Fe release from the oxygen-deficient deep basin on surface phytoplankton production, we combined benthic flux measurements with numerical simulations using the Regional Ocean Modeling System coupled to the Biogeochemical Elemental Cycling (ROMS-BEC) model. For this purpose, we updated the model Fe flux parameterization to include the new benthic flux measurements from the Santa Barbara Basin. Our simulations suggest that benthic Fe fluxes enhance surface primary production, supporting a positive feedback on benthic Fe release by decreasing oxygen in bottom waters. However, a reduction in phytoplankton Fe limitation by enhanced benthic fluxes near the coast may be partially compensated for by increased nitrogen limitation further offshore, limiting the efficacy of this positive feedback.

Alfalfa MsbHLH115 confers tolerance to cadmium stress through activating the iron deficiency response in Arabidopsis thaliana.

Cadmium (Cd) pollution severely affects plant growth and development, posing risks to human health throughout the food chain. Improved iron (Fe) nutrients could mitigate Cd toxicity in plants, but the regulatory network involving Cd and Fe interplay remains unresolved. Here, a transcription factor gene of alfalfa, MsbHLH115 was verified to respond to iron deficiency and Cd stress. Overexpression of MsbHLH115 enhanced tolerance to Cd stress, showing better growth and less ROS accumulation in Arabidopsis thaliana. Overexpression of MsbHLH115 significantly enhanced Fe and Zn accumulation and did not affect Cd, Mn, and Cu concentration in Arabidopsis. Further investigations revealed that MsbHLH115 up-regulated iron homeostasis regulation genes, ROS-related genes, and metal chelation and detoxification genes, contributing to attenuating Cd toxicity. Y1H, EMSA, and LUC assays confirmed the physical interaction between MsbHLH115 and E-box, which is present in the promoter regions of most of the above-mentioned iron homeostasis regulatory genes. The transient expression experiment showed that MsbHLH115 interacted with MsbHLH121pro. The results suggest that MsbHLH115 may directly regulate the iron-deficiency response system and indirectly regulate the metal detoxification response mechanism, thereby enhancing plant Cd tolerance. In summary, enhancing iron accumulation through transcription factor regulation holds promise for improving plant tolerance to Cd toxicity, and MsbHLH115 is a potential candidate for addressing Cd toxicity issues.

Computational Fluid Dynamics Numerical Simulation on Flow Behavior of Molten Slag–Metal Mixture over a Spinning Cup

Centrifugal granulation technology using a spinning cup opens a potential way to recycle steel slag that is currently difficult to reuse. The objective of this research was to study the flow characteristics of a molten slag–metal mixture that was produced during smelting reduction in molten steel slag, passing over a spinning cup, so as to explore the feasibility of using centrifugal granulation technology to treat the steel slag. This was achieved by developing and implementing a computational fluid dynamics (CFD) model that incorporated free-surface multiphase flow to predict the thickness of the liquid slag film at the edge of the spinning cup (slag film thickness for short), which was an important parameter for estimating the size of the slag particles resulting from centrifugal granulation of the molten slag–metal mixture. The influences of various relevant parameters, including spinning cup diameter, slag feeding rate, cup spinning speed, etc., on the slag film thickness were analyzed. Additionally, hot experiments on centrifugal granulation of a molten slag–metal mixture were conducted to verify the results of the numerical simulations. The experimental results indicated a progressive reduction in the Sauter mean diameter of the slag particles as the metallic iron content in the slag increased. Specifically, when the iron content rose from 5% to 15% at a cup spinning speed of 2500 RPM, the Sauter mean diameter decreased by 13.77%. The numerical simulation results showed that the slag film thickness had a positive relationship to the slag feeding rate but a negative relationship to the spinning cup diameter and the cup spinning speed. Furthermore, the ratio between the mean slag particle diameter and the slag film thickness decreased nearly linearly with the increase in the metallic iron content in slag, with the average ratio being approximately 4.25, and this relationship was useful for estimating the slag particle size from the slag film thickness. Therefore, the present research results can provide theoretical guidance for the industrial application of spinning cup centrifugal granulation technology to effectively treat and recycle steel slags.

Aplikasi Formulasi Kapur, Bahan Organik dan Pupuk NPK terhadap Kadar Aluminium dan Besi serta Pertumbuhan Jagung di Lahan Pasca-Tambang Batubara

The level of solubility of aluminum and iron metals in the soil is one of the post-coal mining land problems. The high solubility of Al and Fe can be toxic to plants, so that plants are difficult to grow. This study aims to reduce the solubility of Al and Fe using formulations of liming, organic matter, and NPK fertilizer and to examine their effects on the growth and height of corn in post-coal mining land. The study used a Completely Randomized Design (CRD) with a single factor of ameliorant formulation. The treatment consisted of 10 treatments and was repeated three times, so there were 30 experimental units. The results showed that the application of ameliorant formulation of liming, organic matter, and NPK fertilizer had an effect on decreasing the solubility of Al and Fe in the soil and increasing the growth of corn in post-coal mining land. Soil that has been applied with K1 treatment (lime 3 t ha-1) can give the best results in reducing the solubility of Al and Fe metals in the soil. Application K2 treatment (giving organic matter 10 t ha-1), gave the best results for increasing the growth of corn in post-coal mining land. The best treatment for reducing Al and Fe soluble and increasing plant height growth was found in the treatment of lime 3 t ha-1 + organic matter 10 t ha-1 + NPK fertilizer 50 kg t ha-1, which was 0.42 (me 100g soil-1), 4.48 (ppm) and 108 (cm). The conclusion of this research is that the application of lime formulations, organic materials and NPK fertilizer is able to reduce levels of Al-dd, soluble Fe in the soil and increase the height growth of corn plants. Dolomite is able to reduce Al-dd and Fe-soluble levels. The application of organic and inorganic fertilizers affects the growth of corn height.