Hydrogen-reduced Iron Research Articles

Effect of carbon concentration and carbon bonding type on the melting characteristics of hydrogen-reduced iron ore pellets

Decarbonization of the steel industry is one of the pathways towards a fossil-fuel-free environment. The steel industry is one of the top contributors to greenhouse gas emissions. Most of these emissions are directly linked to the use of a fossil-fuel-based reductant. Replacing the fossil-based reductant with green H2 enables the transition towards a fossil-free steel industry. The carbon-free iron produced will cause the refining and steelmaking operations to have a starting point far from today's operations. In addition to carbon being an alloying element in steel production, carbon addition controls the melting characteristics of the reduced iron.In the present study, the effect of carbon content and form (cementite/graphite) in hydrogen-reduced iron ore pellets on their melting characteristics was examined by means of a differential thermal analyser and optical dilatometer.Carburized samples with a carbon content <2 wt% did not show any initial melting at the eutectic temperature. At and above 2 wt%, the carburized samples showed an initial melting at the eutectic temperature irrespective of the carbon content. However, the absorbed heat varies with varied carbon content. The carbon form does not affect the initial melting temperature, but it affects the melting progression. Carburized samples melt homogenously, while melting of iron-graphite mixtures occurs locally at the interface between iron and carbon particles, and when the time is not long enough, melting might not occur to any significant extent. Therefore, at any given carbon content >2 wt%, the molten fraction is higher in the case of carburized samples, which is indicated by the amount of absorbed melting heat.

Structural Transformation of a (1 – x)Fe2O3–xRuO2 Nanosystem at Different Reduction Temperatures

The phase composition and structure of oxide and hydrogen-reduced iron–ruthenium systems are studied using conversion and adsorption Mossbauer spectroscopy, as well as X-ray diffraction methods. In samples with metal concentration (mass %) 50Fe–50Ru after calcination in air at 773 and 973 K, nanosystems containing two phases with different degrees of dispersion are formed (α-Fe2O3 with an admixture of Ru and RuO2 with an admixture of Fe, respectively). Structural transformations of the nanosystem calcinated at 973 K in different reduction conditions are investigated. It is shown that the formation of nanostructures depends on the initial and final reduction temperatures. The presence of ruthenium substantially changes the reduction kinetics of oxide systems. It is shown that upon an increase in the reduction temperature, the rearrangement of initial stoichiometric oxides to intermediate oxide structures with varying compositions and with different crystal lattice types is observed. The terminating stage of reduction is the formation of metal clusters or solid solutions of intermetallides.

Revised Recommendations for Iron Fortification of Wheat Flour and an Evaluation of the Expected Impact of Current National Wheat Flour Fortification Programs

Iron fortification of wheat flour is widely used as a strategy to combat iron deficiency. To review recent efficacy studies and update the guidelines for the iron fortification of wheat flour. Efficacy studies with a variety of iron-fortified foods were reviewed to determine the minimum daily amounts of additional iron that have been shown to meaningfully improve iron status in children, adolescents, and women of reproductive age. Recommendations were computed by determining the fortification levels needed to provide these additional quantities of iron each day in three different wheat flour consumption patterns. Current wheat flour iron fortification programs in 78 countries were evaluated. When average daily consumption of low-extraction (< or = 0.8% ash) wheat flour is 150 to 300 g, it is recommended to add 20 ppm iron as NaFeEDTA, or 30 ppm as dried ferrous sulfate or ferrous fumarate. If sensory changes or cost limits the use of these compounds, electrolytic iron at 60 ppm is the second choice. Corresponding fortification levels were calculated for wheat flour intakes of < 150 g/day and > 300 g/day. Electrolytic iron is not recommended for flour intakes of < 150 g/day. Encapsulated ferrous sulfate or fumarate can be added at the same concentrations as the non-encapsulated compounds. For high-extraction wheat flour (> 0.8% ash), NaFeEDTA is the only iron compound recommended. Only nine national programs (Argentina, Chile, Egypt, Iran, Jordan, Lebanon, Syria, Turkmenistan, and Uruguay) were judged likely to have a significant positive impact on iron status if coverage is optimized. Most countries use non-recommended, low-bioavailability, atomized, reduced or hydrogen-reduced iron powders. Most current iron fortification programs are likely to be ineffective. Legislation needs updating in many countries so that flour is fortified with adequate levels of the recommended iron compounds.

Efficacy of Pandesal Baked from Wheat Flour Fortified with Iron and Vitamin A in Improving the Iron and Anthropometric Status of Anemic Schoolchildren in the Philippines

Objective: To determine the efficacy of pandesal baked from wheat flour fortified with iron, with or without vitamin A (VA), in improving anemic schoolchildren's iron and anthropometric status.Methods: Anemic 6- to 12-year-old Filipino children (n = 250) received two 60 g pandesal daily for 8 months. They were randomized into 1 of 4 groups: (1) iron-fortified (with hydrogen-reduced iron at 80 mg/kg, electrolytic iron at 80 mg/kg, or ferrous fumarate at 40 mg/kg), (2) iron and VA-fortified, (3) VA-fortified (at 490 RE/100 g), and (4) nonfortified flour. Hemoglobin (Hb) and zinc protoporphyrin (ZnPP) concentrations and weight and height were determined before and after intervention. Analyses of variance and chi-square and multiple regression analyses were performed.Results: Mean Hb increased by 1.3 g/dL (p < 0.001) and mean ZnPP decreased by 24.4 µmol/mol (p < 0.001) after 8 months. Anemia decreased to 26% and iron deficiency decreased from 58% to 12%. After controls were applied for baseline concentration, age, and gender, Hb concentration at post intervention was significantly higher in the Iron + VA group than in the nonfortified group (coefficient = 0.37; p = 0.034). The odds of being iron deficient at post intervention were significantly lower in the Iron group than in the nonfortified group after controls were applied for age, gender, and baseline prevalence (coefficient = 0.12; p = 0.006). None of the 3 fortified groups had significantly different weight-for-age z-score, body mass index-for-age z-score, or height-for-age z-score compared with the nonfortified group after controls were applied for baseline z-scores, age, and gender.Conclusions: Our study shows that in a non–malaria-endemic area, iron fortification of flour significantly reduced the prevalence of iron deficiency among anemic schoolchildren, and double fortification with iron and VA significantly improved Hb status.

Ferrous Gluconate and Ferrous Sulfate Added to a Complementary Food Distributed by the Mexican Nutrition Program Oportunidades Have a Comparable Efficacy to Reduce Iron Deficiency in Toddlers

To assess the efficacy of ferrous sulfate (FS) and ferrous gluconate (FG) as fortificants for a complementary baby food (Nutrisano) to improve the iron status and to reduce the prevalence of anemia in toddlers. Toddlers 12 to 30 months old were randomly assigned to receive either of 3 versions of Nutrisano fortified with FS or FG or not fortified (CG) for 6 months. In final blood samples, the concentrations of hemoglobin, serum ferritin, and soluble transferrin receptors (sTfR) were determined. The effects of treatment on final hemoglobin, ferritin, and sTfR were assessed by multivariate analysis. No significant changes in hemoglobin were observed within or among treatment groups. The prevalence of high sTfR decreased 7.1 percentage points in FG, increased 13.1 percentage points in FS, and increased 0.7 percentage points in CG (P>0.05). In an interaction between treatment and total intake of Nutrisano on the concentration of ferritin, sTfR, and total iron body stores, adjusted means of serum ferritin in the medium tertiles of intake of Nutrisano for FS (P=0.05) and in the higher and medium tertiles for FG were higher (P=0.001), and adjusted means of sTfR were significantly lower (P<0.001), than the respective lower tertile of intake. Fortification of Nutrisano with FG has an acceptable level of beneficial effect on markers of iron status. The satisfactory efficacy and other sensory data has led to the political decision to substitute hydrogen-reduced iron, used formerly as a fortificant, with FG. Studies to assess the effectiveness of the reformulated Nutrisano are in order.

Sensorial Evaluation of Nutritional Supplements (PROGRESA) Enriched with 3 Different Forms of Iron in a Rural Mexican Community

As part of the efforts to reduce iron deficiency anemia (IDA), the Mexican Federal program PROGRESA distributes complementary foods to toddlers and pregnant women living in extreme poverty. Complementary foods were originally fortified with hydrogen-reduced iron, which proved a limited efficacy. The supplement was reformulated to provide higher iron bioavailability. This investigation aims to assess the sensory changes and the acceptance of new versions of the complementary foods fortified with either reduced iron, ferrous fumarate, or ferrous sulfate, stored at room temperature for 2, 4, and 6 mo. Complementary foods were presented without flavor (plain) or flavored with either chocolate or vanilla. The complementary foods were evaluated in toddlers and their mothers using a hedonic scale. The percentage of overall acceptance for the baby foods was higher in toddlers (80% to 88%) than in their mothers (63% to 68%). The complementary foods with a better acceptance were those fortified with reduced iron (63% to 68%) and ferrous fumarate (61% to 80%) independently of the flavoring added. The acceptance of the beverage intended for women was better for those fortified with reduced iron (52% to 63%) or ferrous fumarate (44% to 63%) in their vanilla-flavored version. For women, the most accepted sources of iron were reduced iron (50% to 60%) and ferrous fumarate (50% to 58%).

Effect of Bread Baking on the Bioavailability of Hydrogen-Reduced Iron Powder Added to Unenriched Refined Wheat Flour

Elemental iron powders are widely used to fortify flour and other cereal products. Our objective was to test the hypothesis that baking enhances the bioavailability of elemental iron powders by oxidizing Fe(0) to Fe(2+) or Fe(3+). An in vitro digestion/Caco-2 cell culture model and a piglet model were used to measure bioavailability. Bread flour, either unfortified or fortified with hydrogen-reduced (HR) iron powder or FeSO(4) (300 mg Fe/kg flour), was baked into bread. For the in vitro studies, bread samples were treated with pepsin at pH 2, 3, 4, 5, 6, or 7 and subsequently incubated with pancreatic enzymes at pH 7 in a chamber positioned above monolayers of cultured Caco-2 cells. Ferritin formation in the cells was used as an index of iron bioavailability. Ferritin formation in cells fed HR Fe bread was similar to cells fed FeSO(4) bread when the peptic digestion was conducted at a pH 2 but lower when the peptic phase was conducted at pH 3, 4, 5, 6, or 7 (P < 0.05). Pig diets containing 35% dried bread were prepared and fed to cross-bred (Hampshire x Landrace x Yorkshire) anemic pigs in two studies. The rate of increase in hemoglobin Fe over the feeding period was used to calculate relative biological value (RBV), an index of iron bioavailability. In the first pig study, RBV of HR Fe added to flour prior to baking was 47.9% when compared to FeSO(4) fortified flour (P < 0.05). In the second pig study, a third treatment consisting of unfortified bread with HR iron added during diet mixing (after bread baking) was included. RBVs of the HR Fe diet (Fe added after baking) and HR Fe diet (Fe added before baking) were 40.1% and 53.5%, respectively, compared to the FeSO(4) diet. Differences in RBV between the HR Fe (before and after baking) and FeSO(4) (before baking) treatment groups were significant, but the difference between the before and after HR treatment groups was not significant. We conclude that bread baking does not enhance the bioavailability of elemental iron powders.

Smaller iron particle size improves bioavailability of hydrogen-reduced iron–fortified bread

Bioavailability results, obtained in humans, of wheat flour fortified with elemental iron might not be reliable because these studies have been performed using tracer iron compounds that probably do not have the same physicochemical characteristics as the commercial elemental iron powders. The aim of the present study was to measure, in Caco-2 cells, the iron bioavailability of hydrogen-reduced (H-reduced) iron (≤45- μm particle size) from 72%-extraction wheat flour bread. Bread was fortified with either 8- μm H-reduced iron (pro analysi compound used as control) or ≤45- μm H-reduced iron (industrialized food grade product). Solubility and dialyzability were determined from bread homogenate. Ferritin and intracellular iron content were assessed in Caco-2 cells incubated with either reduced iron or fortified bread homogenate. The 8- μm H-reduced iron had higher solubility and dialyzability than ≤45- μm H-reduced iron. Intracellular iron and ferritin concentrations in Caco-2 cells exposed to digest from bread fortified with 8- μm H-reduced iron were significantly higher than in bread fortified with ≤45- μm H-reduced iron ( P < .05). When bread fortified with ferrous sulfate was used as a reference, the relative iron bioavailabilities of the fortified bread with 8- μm H-reduced iron and ≤45- μm H-reduced iron were 68.2% and 31.1%, respectively. In conclusion, there is an inverse relationship between H-reduced particle size and iron bioavailability. If H-reduced (food grade, ≤45- μm particle size) iron is used in wheat flour fortification, it should be added at 3 times the level of ferrous sulfate to provide the same absolute amount of absorbed iron.

Bread baking does not enhance the bioavailability of hydrogen reduced iron powder

Elemental iron powders, widely used to fortify flour and cereal products, typically have relative biological values of ~50% compared to FeSO4. Our objective was to test the hypothesis that bread baking enhances the bioavailability of elemental iron powders by oxidizing elemental iron (Fe0) to Fe2+or Fe3+. Methods Bread baked with flour fortified with either hydrogen reduced (HR) Fe or FeSO4 (300 mg Fe/kg flour), or no added iron, was dried and milled. Diets contained 35% bread, 35% ground corn, 22% whey protein isolate, a mineral/vitamin premix, and 130 mg Fe/kg. A hemoglobin repletion assay with weanling, iron deficient piglets was used to assess bioavailability. Experiment 1 Crossbred piglets (Hampshire x Landrace x Yorkshire) were divided into two groups and fed diets containing bread fortified, pre-baking, with either FeSO4 or HR Fe. After 16 days, hemoglobin repletion efficiencies (HRE) in the piglets fed HR and FeSO4 fortified breads were 14.9% & 30.9%, respectively (p<0.001). Experiment 2 Similar to experiment 1 except a 3rd treatment consisting of unfortified bread with HR Fe added post-baking was included. After 14 days, HREs in piglets fed the unfortified bread plus HR Fe added post baking, HR Fe fortified bread, and FeSO4 fortified bread, were 6.6%, 8.9%, & 16.1%, respectively. HRE in the FeSO4 group was significantly higher but the 2 HR Fe groups were not different. We conclude that bread baking does not enhance the bioavailability of HR iron powders. Funded by College of Agriculture and Life Sciences, Cornell University.

Comparison of the efficacy of wheat-based snacks fortified with ferrous sulfate, electrolytic iron, or hydrogen-reduced elemental iron: randomized, double-blind, controlled trial in Thai women

Although elemental iron powders are widely used to fortify cereal products, little data exist on their efficacy in humans. We compared the efficacy of wheat-based snacks fortified with ferrous sulfate, electrolytic iron, or hydrogen-reduced iron in Thai women with low iron stores. A double-blind intervention was conducted in 18-50-y-old women (n = 330) randomly assigned into 4 groups to receive either no fortification iron or 12 mg Fe/d for 6 d/wk for 35 wk as ferrous sulfate, electrolytic iron, or hydrogen-reduced iron in a baked, wheat-flour-based snack. Snacks were not consumed with meals, and consumption was monitored. At baseline, 20 wk, and 35 wk, hemoglobin status and iron were measured and the groups were compared. Between baseline and 35 wk, geometric mean serum ferritin (SF) increased significantly in all 3 groups receiving iron (P < 0.01), and geometric mean serum transferrin receptor (TfR) decreased significantly in the groups receiving ferrous sulfate and electrolytic iron (P < 0.05). Calculated mean (+/-SD) body iron stores increased from 1.5 +/- 2.8 to 5.4 +/- 2.9 mg/kg in the ferrous sulfate group, from 1.5 +/- 3.5 to 4.4 +/- 3.6 mg/kg in the electrolytic iron group, and from 1.3 +/- 3.2 to 3.2 +/- 4.3 mg/kg in the hydrogen-reduced iron group (P < 0.01 for all 3 groups) but did not change significantly in the control group. Ferrous sulfate, electrolytic iron, and hydrogen-reduced iron, fortified into wheat-based snacks, significantly improved iron status. On the basis of the change in body iron stores during the 35-wk study, the relative efficacy of the electrolytic and hydrogen-reduced iron compared with ferrous sulfate was 77% and 49%, respectively.

Estimation of the Bioavailability of Iron

Eight laboratories conducted a test for the estimation of the bioavailability of iron from 4 sources, using depleted male albino rats. Ferrous sulfate was used as the reference standard. Ferric orthophosphate was found to have a relative biological value of 11 (range 6-22), an old sample of hydrogen-reduced iron 27 (range 15-41), and ferric citrate 96 (range 75-125). Good results were obtained with a simplified basal diet prepared without ingredients that had previously contributed variable quantities of iron. There was no apparent advantage in using the change in hemoglobin during the repletion period instead of the final homoglobin value as the criterion of response to iron supplements. Several statistical treatments of the data yielded similar conclusions regarding relative biological values of the iron sources.