INFLUENCE OF THE RATE OF IRON HEXATIANOFERRATE ON ITS SORPTION ABILITY IN RELATION TO SILVER, INDIUM AND GALLIUM CATIONS

The processing of phosphorites into elemental phosphorus is accom-panied by the formation of waste - cotrile "milk", in which indium, gallium, and silver are present. This waste can be considered as a cheap raw material for the production of rare and precious metals. In the scientific literature there are data on the sorption capacity of hexacyano-ferrates of iron, which has a crystal lattice with a channel diameter from 3.0 to 3.5Å. Investigation of the sorption process in the model system "Fe4[Fe(CN)6]3·10H2O - Ag+- In3+- Ga3+ - H2O" depending on the norm of iron hexacyanoferrate (sorbent). The initial concentration of silver, indium and gallium ions and their residual content in solutions were determined using the atomic absorption spectrophotometer "PerkinElmer Analyst 400" (USA). The microstructure of the initial iron hexacyanoferrate and iron hexacyano-ferrate, after sorption, was studied on the CarlZeissFESEM and JEOL brand "JXA-8230" (Japan). With a ratio to T:W equal to 1.75-2.5:100, the degree of sorption of Ag+ with iron hexacyanoferrate is 99.5 and 99.8 %. The highest degree of sorption (96.75%) of In3+ ions can be obtained with a sorbent weighing 3 g per 100 g of solution at 60oC. A high degree of sorption of Ga3+ cations is achieved at low (0.5:100 wt. h.) and high (3:100 wt. h.) consumption of iron hexacyanoferrate. It was revealed that iron hexacyanoferrate exhibits sorption properties simultaneously with respect to mono- and trivalent metals, and the basic laws of their sorption were established.

Comparative Analysis of Aminopolycarboxylate Chelants Improves Iron Control in Acidizing Operations

Aminopolycarboxylate-based chelants are used to control iron precipitation during acidizing operations by interacting directly with the iron, resulting in water-soluble complexes. This paper highlights that, in order to improve the effectiveness of iron control during acidizing operations, the type and the concentration of the chelants should be based on the formation properties and the well characteristics by comparing the cheltors’ performance as iron-control agents at different temperatures and pH environments with different levels of iron concentrations and chelant to iron molar ratios in acid (HCl). This study also addresses the interactions between the tested iron-control additives and acid, as well as the performance of the chelants in carbonate cores. Laboratory experiments were conducted to investigate the performance of nitrilotriacetic acid (NTA), glutamic acid, N, N-diacetic acid (GLDA), diethylenetriaminepentaacetic acid (DTPA), ethylenediamine-tetraacetic acid (EDTA), and hydroxyethylethylenediaminetriacetic acid (HEDTA) as iron control additives in 5 wt% HCl at pH values 0 to 4.5 to simulate carbonate acidizing at temperatures of 70 to 300°F, and initial iron concentrations of 2000 ppm. The performance of NTA and EDTA was also compared at higher initial iron concentration (4000 ppm). This work also quantified the effects of acid additives such as corrosion inhibitor and non-ionic surfactant on the chelation performance. Coreflood experiments using carbonate cores in acid with chelant helped determine its influence on permeability. Testing chelant-to-acid molar ratios of 1:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1, and 2:1 relative to iron concentration yielded optimal values. Additional tests monitored iron precipitation in solution using an inductively coupled argon plasma (ICAP) emission spectroscopy. Precipitates were filtered and analyzed using X-ray diffraction (XRD), X-ray fluorescence (XRF), and scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS). Without chelant, at 70°F and 2000 ppm initial iron concentration, precipitation began at pH 1.45 and completed by pH 2.42. At 150 and 210°F, iron precipitated at pH 0.68 and 0.3 and completed by pH 1.3 and 1, respectively. At 70°F, NTA showed a minimum of 98% chelation at pH 4.3; however, its performance declined at 150°F to 74% chelation at pH 4.24, and at 210°F to 53% chelation at pH 4.0. Although DTPA dissolves completely in live acid, precipitations occurred at partially spent acid. At pH 0.15, SEM-EDS showed that the precipitate contains as much as 13 wt% iron. Thus, DTPA is not a suitable iron-control agent. HEDTA showed a 90% chelation at 210°F and pH 4.8. GLDA's performance declined to less than 50% at 150°F. At higher iron concentrations of 4000 ppm, Na3NTA kept all iron in solution in a 5 wt% HCl up to pH 4.0 at 70°F and its performance declined to a minimum of 97% at pH 4.7 at same temperature. At 150°F, and 210°F, Na3NTA started to gradually decline at pH values greater than 3.9, and 3.5, respectively. The minimum chelation reached by NTA was 91% at pH 4.4, at 150°F, and 73% at pH 4 at 210°F. Upon comparing the NTA's results at high iron concentrations to the popular EDTA, Na4EDTA at 1-to-1 mole ratio with iron exceeded its maximum solubility in 5 wt% HCl and precipitated in the original solution. For NTA, a molar ratio of 1.4:1 is optimal at 70 and 150°F, showing chelation performance of 95% and 94%, respectively, while a molar ratio of 1.5:1 is optimal at 210°F, showing a chelation performance of 87%. This study's results improve field operations by identifying NTA and HEDTA as having the best iron-control chelation performance of the five additives tested, thus reducing guesswork and streamlining production. The work also provided recommendations for choosing the best type of iron-control agent based on solubility and coreflood analysis. The results can be used to design more efficient acidizing fluids. This work won second place in the Masters division of the 2020 Gulf Coast Regional Student Paper Contest, April 2020.

N-terminal tyrosine of ISCU2 triggers [2Fe-2S] cluster synthesis by ISCU2 dimerization

Synthesis of iron-sulfur (Fe/S) clusters in living cells requires scaffold proteins for both facile synthesis and subsequent transfer of clusters to target apoproteins. The human mitochondrial ISCU2 scaffold protein is part of the core ISC (iron-sulfur cluster assembly) complex that synthesizes a bridging [2Fe-2S] cluster on dimeric ISCU2. Initial iron and sulfur loading onto monomeric ISCU2 have been elucidated biochemically, yet subsequent [2Fe-2S] cluster formation and dimerization of ISCU2 is mechanistically ill-defined. Our structural, biochemical and cell biological experiments now identify a crucial function of the universally conserved N-terminal Tyr35 of ISCU2 for these late reactions. Mixing two, per se non-functional ISCU2 mutant proteins with oppositely charged Asp35 and Lys35 residues, both bound to different cysteine desulfurase complexes NFS1-ISD11-ACP, restores wild-type ISCU2 maturation demonstrating that ionic forces can replace native Tyr-Tyr interactions during dimerization-induced [2Fe-2S] cluster formation. Our studies define the essential mechanistic role of Tyr35 in the reaction cycle of de novo mitochondrial [2Fe-2S] cluster synthesis.

Conservative Islamic factions vs. secular nationalists: toward a civil contestation in democratic Indonesia

This paper describes how Indonesia’s presidents have delt with Islamist and secular nationalist political contestation since the preparation of Indonesian independence and how the current president compares. Soekarno’s initial reliance on civil discourse ended in his autocratic decree that banned the Indonesia’s most powerful Islamic party (Masyumi). Soeharto’s initial iron-fist approach ended up meeting some Islamic demands. B.J. Habibie helped transformed Indonesia through a democratic election in 1999, but the leader of the winning party, Megawati was defeated in the parliament that elected a pluralist Muslim cleric, Gus Dur. Gus Dur’s administration, ended by the central axis, suggests that liberal democratic processes cannot be applied in an increasingly conservative Muslim majority country. Megawati lost, partly because she is a female president unpopular among the Islamists, while SBY was sympathetic toward the Islamist’s demands, enhancing the “conservative turn.” Jokowi has used discursive and legal approaches to promote Pancasila in challenging the hardline Islamic demands, enabling him to ban HTI and FPI and to implement the speech freedom-limiting laws, leading to criticisms and the decline in the 2020 Indonesia's Democracy Index. Jokowi’s expansion of these laws to maintain unity and stability may be deemed an “authoritarian turn,” but I argue that it may be more appropriately called “the Pancasila turn.” In framing and analyzing Jokowi’s laws as a Pancasila turn, I am arguing in this paper that this lays the foundation for a more equal, civil, and democratic contestation.

Homogeneous Cytochrome 579 Is an Octamer That Reacts Too Slowly With Soluble Iron to Be the Initial Iron Oxidase in the Respiratory Chain of Leptospirillum ferriphilum

The exact role that cytochrome 579 plays in the aerobic iron respiratory chain of Leptospirillum ferriphilum is unclear. This paper presents genomic, structural, and kinetic data on the cytochrome 579 purified from cell-free extracts of L. ferriphilum cultured on soluble iron. Electrospray mass spectrometry of electrophoretically homogeneous cytochrome 579 yielded two principal peaks at 16,015 and 16,141 Daltons. N-terminal amino acid sequencing of the purified protein yielded data that were used to determine the following: there are seven homologs of cytochrome 579; each homolog possesses the CXXCH heme-binding motif found in c-type cytochromes; each of the seven sequenced strains of L. ferriphilum expresses only two of the seven homologs of the cytochrome; and each homolog contains an N-terminal signal peptide that directs the mature protein to an extra-cytoplasmic location. Static light scattering and macroion mobility measurements on native cytochrome 579 yielded masses of 125 and 135 kDaltons, respectively. The reduced alkaline pyridine hemochromogen spectrum of the purified cytochrome had an alpha absorbance maximum at 567 nm, a property not exhibited by any known heme group. The iron-dependent reduction and oxidation of the octameric cytochrome exhibited positively cooperative kinetic behavior with apparent Hill coefficients of 5.0 and 3.7, respectively, when the purified protein was mixed with mM concentrations of soluble iron. Consequently, the extrapolated rates of reduction at sub-mM iron concentrations were far too slow for cytochrome 579 to be the initial iron oxidase in the aerobic respiratory chain of L. ferriphilum. Rather, these observations support the hypothesis that the acid-stable cytochrome 579 is a periplasmic conduit of electrons from initial iron oxidation in the outer membrane of this Gram-negative bacterium to a terminal oxidase in the plasma membrane.

PSIV-9 A Multistate Evaluation of an Additional Iron Injection Administered to Piglets Before Weaning

A cooperative study utilizing 514 weanling pigs from 7 experiment stations was conducted to determine the effects of an additional iron injection administered to piglets before weaning on growth performance and hematological measures. All pigs received an initial iron injection at the time of processing postfarrowing. At each station, pigs were assigned to either the control or an added-injection treatment by pairing two same-sex pigs with a BW difference ≤ 0.453 kg within a litter. One pig within each pair received the additional iron injection (same dose received at processing) 3 to 5 days preweaning. Once weaned, both the control and added-injection group received common station-specific nursery diets. Body weight was recorded weekly by all stations. Blood samples were also collected at second injection, weaning, 14 and 28 days postweaning by 3 of the 7 stations. All data were subjected to ANOVA with the model containing the terms treatment, station, and treatment by station interaction. Average daily gain (Table 1) was greater for the added-injection group during d 0 to 14 (212.5 vs. 202.6 g, P = 0.03) which resulted in an increase in d 14 BW (P = 0.05). Although there was no treatment effect for overall ADG (d -4 to d 28), the tendency for a treatment by station interaction (P = 0.09) illustrated both responsive and nonresponsive stations, indicating that iron status was not the most limiting factor for growth at all stations. Hemoglobin concentration was greater (P < 0.0001) for the added-injection group at weaning and d 14 postweaning. In conclusion, an additional iron injection administered before weaning may lead to early success in the nursery resulting in a heavier BW in subsequent periods; however, the beneficial effects of an additional iron injection are likely dependent on herd status and characteristics.

Optimization of the Process of Unloading of Iron Ore Raw Materials: The Case of a Steel Plant

The process of unloading iron ore raw materials of the metallurgical plant to the sinter plant has not been considered for a long time as a particular topic. Over the last years the conditions of metallurgical production have undergone certain changes: its intensification has occurred, which entails the need to re-evaluate parameters of stable operation of sinter production. The objective of the suggested study is to consider the issues of possible technical and technological improvement harmonizing transport flows with the requirements of the main production process. To achieve this goal, a technique of mathematical modelling is used, based on the mathematical apparatus of linear programming; graphic-analytical method; method of probability theory.The issues of the process of unloading, storage of iron ore raw materials, of their preparation for sinter production are primarily considered.The article presents the main positions of the process of optimizing unloading of sinter batch of a metallurgical plant.The general characteristics of the technology of metallurgical production and of each particular process are described. The agglomeration process is considered in more detail. The tables of initial iron ore raw materials for sintering production for certain reporting periods are given, for the sake of clarity, the data of one of the tables are summarized in a diagram. A diagram of a standard trestle-type ore warehouse is considered, which sequentially shows the main processes of sintering production from supply of raw materials to the car dumper to getting through a belt conveyor into a stack, and then into receiving bins. The article also provides an example of formation of piles of iron ore raw materials using manganese limestone.The study is based on a dynamic transport problem with delays (DTPD), which considers time of transportation of goods, the dynamics of production volumes over time, the dynamics of consumption, the dynamics of stocks of suppliers and consumers, dynamics of cost of transportation and storage, dynamics of cost of consumption losses. The study contains several mono-problems with a mono load, which overlap each other, forming a multiplicative overlay of single-product problems.

Reverse Combined Microflotation of Fine Magnetite from a Mixture with Glass Beads

Magnetite is an essential iron-bearing mineral. The primary method of magnetite ore beneficiation involves successive steps of crushing, grinding, and magnetic separation. Reverse cationic flotation is used at the final stage to remove silicate and aluminosilicate impurities from the magnetite concentrate and reduce silica content to 1–3%, depending on metallurgical processing route (electrometallurgy, direct iron reduction). In view of the stringent demands of the magnetite concentrate grade, before flotation, the ore is currently routinely ground down to a particle size below 35 µm, and magnetite particles are ground to a size below 10 µm. This significantly reduces the efficiency of flotation and increases iron loss in the tailings due to the hydraulic report in froth being up to 15–25%. Combined microflotation (CMF) looks to be a promising method of increasing fine-particle flotation efficiency, as it uses relatively small amounts of microbubbles alongside conventional coarse bubbles. Microbubbles act as flotation carriers, collecting gangue particles on their surface, which then coarse bubbles float. The purpose of this study is to explore the effectiveness of CMF for processing a model mixture that contained magnetite particles smaller than 10 µm and glass beads (Ballotini) below 37 µm in size when the initial iron content in the mixture was 63.76%. Commercial reagent Lilaflot 821M was used as both collector and frother. The flotation procedure, which included the introduction of 15 g/t of the collector before the start of flotation, and the addition of 5 g/t of the collector in combination with a microbubble dose of 0.018 m3/t 6 min after starting flotation, ensured an increase in the concentrate grade to 67.63% Fe and iron recovery of 91.16%.

Improving the quality of silicon metal by the method of x-ray radiometric separation of raw material and finished products

In this research, we investigate the process of X-ray radiometric separation of both raw materials (quartz, carbonaceous reducing agent) used for silicon smelting in ore-smelting furnaces and the resulting smelting products. The research objects were quartz from the Aktas field (Kazakhstan), coal from the Shubarkol field and silicon metal of various grades smelted at the Tau-Ken Temir LLP (Karaganda, Kazakhstan). X-ray diffraction analysis was performed using a Philips powder diffractometer. To determine the SiO2 and Fe2O3 content, an ARL PERFORM’X X-ray fluorescence spectrometer was used. To remove impurities, a СРF1-150М single-strand radiometric separator was used. We found that the radiometric separation of original quartz samples with the Fe2O3 content of ~ 0.1-0.15% produces pure quartz with the Fe2O3 content of ≤ 0.05% and a yield of 65-70%. Provided that the Fe2O3 content in the original quartz sample does not exceed 0.5%, concentrates with the Fe2O3 content of 0.05% and a yield of 35-55% can be obtained. The yield of pure quartz with the Fe2O3 content of 0.01% does not exceed 15-20%. The use of radiometric separation is established to reduce the amount of phosphorus in the final product by 2-3 times. This method is effective for obtaining coal concentrates of varying ash content (2.0, 4.1 and 7.3%); the resulting concentrated product obtained with a yield of 25% contains 1.5% of ash. Separation of silicon metal (with the initial iron content of 1.2-1.5%) yields a product matching silicon grade 773 (product yield ~ 50%), 553 (~ 35%) or 441 (20%). It is concluded that radiometric separation allows the content of impurities in quartz, silicon metal and coal ash to be reduced, thus facilitating the production of higher-grade silicon.