Fine Iron Research Articles

Effect of an acid mine spill on soils in Sonora River Basin: Micromorphological indicators

The role of soil could be decisive for the neutralization of the acid solution and immobilization of the metallic contaminants produced by mining industry. We studied micromorphological indicators of the interaction between the acid solution and soil material in the profile of Fluvisol at the Bacanuchi river (Sonora River Basin, Mexico) terrace affected by the catastrophic mine spill and in analyzing sample from a soil column treated with an acid liquid imitating the spill. Original unaffected soil is sandy with poorly developed pedogenetic features, however, frequent primary and secondary micritic and sparitic carbonates define high pH values. In the soil influenced by acid solutions under natural and laboratory conditions, carbonates were absent whereas neoformed gypsum crystals with radial intergrowth were observed together with accumulation of fine material enriched in ferruginous pigment. Micromorphometric quantification of the iron-rich fine material has shown its increase after interaction with the acid solution. We conclude that the interaction consisted of the neutralization reaction between the more reactive phases of the soil and the acid solution during which carbonates were consumed and gypsum was neoformed. Fine iron oxides precipitated after neutralization of acidity, the pH increased and the color changed. It is highly probable that other metallic contaminants co-precipitated with the ferruginous components.

The Effect of Carbon Dissection of Waste Plastics on Inhibiting the Adhesion of Fine Iron Ore Particles during Hydrogen Reduction

In this research, Australian fine iron ore was reduced by combining pressurized and energy-bearing waste plastics in a fluidized bed. This research aims to obtain preferable operating parameters by synthetically researching the effect of temperature, linear velocity, pressure, size, and mass content of energetic waste plastics, and to clarify the sticking mechanism and the inhibitory mechanism of fine iron ore during the reduction process. The experimental results show that the preferable operating parameters include a reduction temperature of 923–973 K, linear velocity of 0.8 m/s, reduction pressure of 0.15 MPa, particle size of energetic waste plastics of 0.18–0.66 mm, and mass content of energetic waste plastics of 8%. Under the conditions of theses preferable operating parameters, the sticking mechanism of fine iron ore is caused by the reunion of the metal iron atoms. The occurrence states of carbons deposited from waste plastics can be divided into two types: graphite and carbon from Fe3C. Carbon from Fe3C reduces the sticking of fine iron ore, while the graphite hinders the direct contact of iron atoms, thereby effectively controlling the sticking.

The Effect of Pressurized Decarbonization of CO on Inhibiting the Adhesion of Fine Iron Ore Particles

In this research, Australian fine iron ore is reduced by pressured carbon monoxide in a fluidized bed. This research aims to obtain the influence law of gas linear velocity, reduction pressure, reduction temperature, particle size, and reduction time on the reduction effect and the economic, convenient, and effective operating parameters, as well as clarify the effect of the pressurized decarbonization of CO, which inhibits the adhesion of fine iron ore particles during the reduction process. The experimental results show that the preferable operating parameters are a linear velocity of 0.8 m/s, reduction pressure of 0.2 MPa, reduction temperature of 1023 K, and particle size of 0.18 mm–0.66 mm. The graphite produced by the carbon precipitation reaction of carbon monoxide hinders the diffusion of iron atoms and avoids the direct contact between the iron atoms, thereby effectively controlling the sticking.

On the Mechanism by which Chromium Improves Strip Surface Cleanliness in Steel Strip Cold Rolling

“Detachable iron particles” or iron fines due to abrasive interactions in the roll bite between the roll surface and the strip are one of the major cleanliness defects. They may induce surface defects in particular on galvanizing lines. Chrome plating of rolls is generally recognized to result in a better strip surface cleanliness. In the present paper, the reasons for the success of chrome plating in this respect are investigated. An end-of-life industrial roll has been ground by parts under several conditions (Ra = 0.4 μm, 1.0 μm, 1.6 μm ± 0.1 μm), then cut into pieces for observation as well as for manufacturing tribological test tools (Plane Strain Compression Test, PSCT). Some of these pieces have been chrome-plated, the others not for comparison. Careful examination of just ground and chrome-plated roll has revealed that ground surface bears a number of rather aggressive features. Chrome plating covers them with a gentler pattern, although preserving the roughness in terms of Ra to maintain sufficient friction for correct mill operation. PSCT confirms that there is less wear debris on the strip when using Cr-plated tools.

Nutrient Fluxes From Profundal Sediment of Ultra‐Oligotrophic Lake Tahoe, California/Nevada: Implications for Water Quality and Management in a Changing Climate

AbstractA warming climate is expected to lead to stronger thermal stratification, less frequent deep mixing, and greater potential for bottom water anoxia in deep, temperate oligotrophic lakes. As a result, there is growing interest in understanding nutrient cycling at the profundal sediment‐water interface of these rare ecosystems. This paper assessed nutrient content and nutrient flux rates from profundal sediment at Lake Tahoe, California/Nevada, USA. Sediment is a large reservoir of nutrients, with the upper 5 cm containing reduced nitrogen (∼6,300 metric tons) and redox‐sensitive phosphorus (∼710 metric tons) equivalent to ∼15 times the annual external load. Experimental results indicate that if deep water in Lake Tahoe goes anoxic, profundal sediment will release appreciable amounts of phosphate (0.13–0.29 mg P/m2·d), ammonia (0.49 mg N/m2·d), and iron to overlaying water. Assuming a 10 year duration of bottom water anoxia followed by a deep‐water mixing event, water column phosphate, and ammonia concentrations would increase by an estimated 1.6 µg P/L and 2.9 µg N/L, nearly doubling ambient concentrations. Based on historic nutrient enrichment assays this could lead to a ∼40% increase in algal growth. Iron release could have the dual effect of alleviating nitrate limitation on algal growth while promoting the formation of fine iron oxyhydroxide particles that degrade water clarity. If the depth and frequency of lake mixing decrease in the future as hydrodynamic models suggest, large‐scale in‐lake management strategies that impede internal nutrient loading in Lake Tahoe, such as bottom water oxygen addition or aluminum salt addition, may need to be considered.

The use of Papuan iron sand and river sand for fine aggregate in mortar for nuclear radiation shield application

This study explores the effect of fine aggregate on mortar properties and its application as a nuclear shield. This study was based on a hypothesis that the types of aggregate applied as radiation shield determined the level of its effectiveness on preventing nuclear radiation. There are two types and sources of fine aggregate that was used as main ingredients for mortar production in this research, namely iron sand and river sand. Both types of sand were derived from the respective regions of Sarmi and Jayapura, Papua. The results showed that the mortar materials that were produced with the iron sand provided better results in dispelling radiation than that of river sand. The compressive strength of fine aggregate from the iron sand was 21.62 MPa, while the compressive strength of the river sand was 16.8 MPa. Measuring the attenuation coefficient of material, we found that the largest aggregated value of mortar with fine iron sand reached 0.0863 / cm. On the other hand, the smallest HVT (Half Value Thickness) was obtained from the iron sand mortar, at 8.03 cm.

Assessment of changes in the content of toxic elements (Pb, As, Hg, Cd) in aboveground parts of wheat Triticum vulgare Vill under the influence of insertion into the soil an aqueous suspension of humic acids with different forms of iron

Lack of iron leads to a weakening of plant growth and lower yields. A promising solution to this problem is the use of nanoparticles of iron, iron oxides as biostimulators of growth of agricultural plants. However, the special properties of nanoparticles can enhance the mechanisms associated with toxic effects on living organisms, lead to trace elements. The response of plants to the impact of iron is highly variable and depends on their genotype and species. Literature data on the influence of fine iron particles on the elemental composition of the plant species Triticum vulgare Vill (soft wheat) is not enough, in addition, virtually no study of the interaction of these particles with natural sorbents - humic acids, which control the bioavailability and transport of elements in natural objects. Therefore, the article presents data on the content of toxic elements (As, Hg, Cd, Pb) in the aboveground part of wheat plants Triticum vulgare Vill. Wheat is cultivated in the soil under the influence of aqueous solutions Fe0 spherical iron nanoparticles (diameter of 80 ± 5 nm), magnetite Fe3O4 (50- 80 nm width and a height of 4-10 nm), ionic forms of diand trivalent iron sulphate with addition of humic acids isolated from the brown coal of the Tulgan deposit. The results of the study showed that under the influence of iron and magnetite nanoparticles, the replacement of more toxic mercury with less toxic cadmium is observed, but the total number of these elements remains constant. An aqueous solution of trivalent iron sulfate with a concentration of 0.0001 g/l contributes to the maximum reduction of toxic elements (lead, arsenic, mercury and cadmium) in the aboveground part of wheat plant.

Effect of characteristics of fine iron ores on the granulation behavior of concentrate in sintering granulation process

Concentrates have advantages of high ferrous grade, less harmful impurities and lower price. However, the small size and poor granulation behavior of concentrates could deteriorate the permeability of the sinter bed and reduce sinter productivity, thus making it difficult to use concentrates effectively. Therefore, in order to strengthen the granulation behavior of concentrates, granulation experiments were carried out and experiment samples made with one kind of concentrates and five kinds of fine iron ores were produced in this paper. Then, the effects of water absorbility and wettability of fine iron ores on granulation behavior of concentrates were investigated. Furthermore, optimized ore blending recipes were proposed to strengthen the granulation behavior of concentrates by sinter pot tests. Results show that the granulation behavior of concentrates was improved for the samples exhibiting high maximum capillary water and small contact angle in fine iron ores. Compared with the scheme of blending ores containing 15 mass% concentrate, the growth index of quasi-particles increased by 20.62% in the case of iron ore BR-2 replacing half of iron ore BR-1, the vertical sintering speed went up from 26.32 to 29.26 mm min−1, the productivity increased from 1.95 to 2.20 t m−2 h−1. The growth index of the quasi-particles increased by 30% when using iron ore AR-2 to replace half of iron ore AR-1. The vertical sintering speed and the productivity of sinter improved to 29.82 mm min−1 and 2.24 t m−2 h−1, respectively. The results help to improve the granulation behavior of concentrates by optimizing the blending ore recipes, based on the characteristics of fine iron ores, and thus use these concentrates more efficiently in the sintering process.

Hard-yet-tough high-vanadium high-speed steel composite coating in-situ alloyed on ductile iron by atmospheric plasma arc

A graded high-vanadium alloy composite coating was synthesized from premixed powders (V, Cr, Ti, Mo, Nb) on ductile iron (DI) substrate via atmospheric plasma arc surface alloying process. The resulted cross-section microstructure is divided into three distinct zones: upper alloyed zone (AZ) rich with spherical primary carbides, middle melted zone (MZ) with fine white iron structure and lower heat affected zone (HAZ). Spherical or bulk-like primary carbides with diameter < 1 μmin the AZ are formed via in-situ reactions between alloy powders and graphite in DI. Microstructural characterizations indicate that the carbides are primarily MC-type (M=V, Ti, Nb) carbides combined with mixed hardphases such as M 2C, M7C3, M23C6, and martensite. Disperse distribution of spherical, submicron-sized metal carbides in an austenite/ledeburite matrix render the graded coating hard-yet-tough. The maximum microhardness of the upper alloyed zone is 950 HV0.2, which is five times that of the substrate. Significant plastic deformation with no cracking in the micro-indentations points to a high toughness. The graded high-vanadium alloy composite coating exhibits superior tribological performance in comparison to Mn13 steel and plasma transferred arc remelted DI.

Replicate Imaging of a Unicellular Plant through a GlassBarrier Using Fine Iron Particles: Evidence for Electromagnetic Energy Transfer

Introduction: Previously we utilized a method for imaging electromagnetic fields from plant and animal tissues. We applied the same methodology to single cell organisms.Methods: A clean glass slide served as a base. A coverslip was placed on the base. A drop of culture media containing the single cell plant, Euglena gracilis was placed on the coverslip and covered by another coverslip to enclose the organisms. A second coverslip “sandwich” (SDW) containing fine iron particles (mean diameter 2 microns) mixed with a potassium ferrocyanide iron staining solution was placed over the underlying coverslip SDW. The second SDW was offset so that a portion was not covering the area with the microorganism, thereby serving as a control. When all of the liquid had evaporated (24 - 48 hours) the area encompassed by the images of the encysted cells were quantified using the Image Pro-plus histomorphometry software program and compared to similar images of actual encysted cells from dried specimens for the same time periods (each group, n = 5).Results: Initially we observed mobile, rod shaped, single cell organisms with rounded ends. After 24 - 48 hours, the second coverslip showed images of the immobile of encysted, cells whose appearances were identical and whose area measurements were not significantly different (p ≥ 0.6) than the actual encysted cells.Conclusions: These finding demonstrate that replicate images of the single cell plant, Euglena gracilis, can be retrieved through a glass barrier. The evidence suggesting that electromagnetic energy may provide a possible mechanism underlying these replicate images is illustrated and discussed.

Microstructure evolutions of graded high-vanadium tool steel composite coating in-situ fabricated via atmospheric plasma beam alloying

A novel high-vanadium based hard composite coating was synthesized from premixed powders (V, Cr, Mo, Ti, Nb) on ductile iron (DI) substrate via atmospheric plasma beam surface alloying process. The graded coating can be divided into three distinct zones: upper alloyed zone (AZ) rich with spherical primary and eutectic submicron carbides, middle melted zone (MZ) with fine white iron structure embedded with high-carbon martensite and lower heat affected zone (HAZ) where martensite/ledeburite double shells were substantially formed. Spherical or bulk-like primary carbides with diameter <1 μm in the middle AZ were formed via in-situ reactions between alloy powders and graphites in DI, presenting a refined microstructure similar to high vanadium-containing tool steel. Microstructural characterizations indicate the carbides are chiefly globular MC-type particles mixed with hard-phases such as M2C, M7C3, M23C6, and martensite. EDS mappings show that MCs (M = V, Ti, Nb) form together while M2C-type carbides tend to locate at the grain boundary or around the MC particles. Ti and Nb occur in the MC-type primary carbides besides V and TiC even features as nuclei. Though dependent upon the size, shape, type and distribution of carbides, the microhardness was obviously enhanced in both AZ and MZ.

Early-age hydration characteristics of composite binder containing iron tailing powder

The early-age hydration characteristics of composite binder containing iron tailing powder were investigated by determining the hydration heat, non-evaporable water content, pore structure, and morphology of hardened paste as well as the compressive strength of mortar. The results show that the reaction degree of iron tailing powder is extremely low at early age. Addition of coarse iron tailing powder negatively affects the properties of composite binder paste and mortar. Compared to samples containing coarse iron tailing powder, the samples containing fine iron tailing powder show a large amount of hydration heat, high non-evaporable water content, fine pore structure of hardened paste and high compressive strength of mortar. The iron tailing powder significantly promotes the hydration of binder at low water-to-binder ratio. The iron tailing powder particles are well graded with cement particles in the paste, but the large iron tailing powder particles bond poorly with the surrounding hydrates. The decreasing ratio of compressive strength of mortar is much lower than the replacement level of iron tailing powder, especially for the mortar containing fine iron tailing powder at low water-to-binder ratio.

ПОВЫШЕНИЕ УСТАЛОСТНОЙ ПРОЧНОСТИ И РАБОТОСПОСОБНОСТИ КОНСТРУКЦИОННЫХ СТАЛЕЙ ДОПОЛНИТЕЛЬНОЙ ХИМИКО-ТЕРМИЧЕСКОЙ ОБРАБОТКОЙ С ИСПОЛЬЗОВАНИЕМ АЗОТИСТО-УГЛЕРОДИСТЫХ КАРБЮРИЗАТОРОВ

Modern methods of chemical-thermal treatment (CTT) such as cyanidation, nitrogen casehardening and others are widelyused in different branches of industry and they are processes promising enough. The solution of ecological problems of diffusion strengthening and improvement of performance attributes of a surface layer are interrelated with the use of special powder mixtures – lutes, pastes, called saturating environment (carburizer). As a saturating environment in the work there is used a nitrogen-carbon paste on the basis of fine gas black (amorphous carbon ~ 60%) and iron sinergisty potassium ~ 40% with the addition of carbamide (urea) as a nitrogen-containing component. A saturating pasty environment on the basis of soot with nitrogen-containing admixtures (urea and iron sinergisty potassium) is efficient for the surface strengthening treatment of steel products in a wide range of temperatures. Solid carbonitrides arising on the surface of products processed in this environment promote the increase of their wear-resistance and other performance attributes. A carbonitride edge on the surface of steel (20…30) ChGT arising at nitrogen case-hardening in a paste-type carburizer does not decrease wear-resistance, but, at the same time increases working capacity of parts and units and material fatigue resistance.

Direct reduction of fine iron ore concentrate in a conical fluidized bed

The direct utilization of fine iron ore concentrate in fluidized beds is of significance but has the problem of defluidization during operation. In this study, we have made a comparison of a conical fluidized bed and a cylindrical fluidized bed for the direct reduction process. The results showed that the conical fluidized bed was more versatile than the cylindrical fluidized bed in treating the fine iron ore concentrate. In the conical fluidized bed, with a high superficial gas velocity, defluidization was successfully inhibited without adding inert materials or causing elutriation issues. Simultaneously, the reduction efficiency was considerably improved and the obtained iron agglomerates exhibited a high metallization degree. This work also proposes a fluidization regime diagram for the conical fluidized bed at the temperature range from 650 to 800°C. According to the fluidization regime diagram, the conical fluidized bed is able to considerably expand the operational temperature range for the direct reduction process. These results demonstrate that the conical fluidized bed is a clean, efficient alternative means for intensifying the direct reduction process.

Simulation of In-Flight Reduction of the Fine Iron Ore Concentrate by Hydrogen

Abstract A mathematical model has been proposed to simulate a novel method for direct reduction of iron concentrate by hydrogen. Flight of fine particles in a vertical reactor containing a gaseous mixture of H2-N2-H2O has been studied. Effect of generating gaseous jet on the residence time of the particles has been also investigated. Coupled turbulent Navier-Stokes equations with eddy kinetic energy equation have been solved using a developed homemade code. Kinetics of this reaction has been studied using the unreacted core model. Accuracy of the model predictions has been approved by the experimental data. Finally, effects of vital variables (i. e. temperature, particle size, hydrogen concentration and particle feed rate) on the particle residence time and also fractional conversion have been studied.

Multistep Reduction Kinetics of Fine Iron Ore with Carbon Monoxide in a Micro Fluidized Bed Reaction Analyzer

The reduction kinetics of Brazilian hematite by CO is investigated in a Micro Fluidized Bed Reaction Analyzer (MFBRA) using an analyzing method based on Johnson-Mehl-Avrami (JMA) model at temperatures of 973 K (700 °C), 1023 K (750 °C), 1073 K (800 °C), and 1123 K (850 °C). The solid products at different reduction stages are evaluated by SEM/EDS and XRD technologies. Results indicate that the reduction process is better to be discussed in terms of a parallel reaction model that consists of the reactions of hematite to wustite and wustite to iron, rather than a stepwise route. Meanwhile, the controlling mechanism of the reduction process is found to vary with temperature and the degree of conversion. The overall process is controlled by the gas–solid reaction occurring at the iron/wustite interface in the initial stages, and then is limited by the nucleation of wustite, and finally shifts to diffusion control. Moreover, the reactions of hematite to wustite and wustite to iron take place simultaneously but with different time dependences, and the apparent activation energies of hematite to wustite and wustite to iron are determined as 83.61 and 80.40 KJ/mol, respectively.

微粉鉄鉱石の多量使用に向けた整粒強化型の新造粒プロセス

微粉鉄鉱石の多量使用に向けた整粒強化型の新造粒プロセス

Copper Hardening with Fine Iron Particles

The production of sintered bulk Cu–(5–25% Fe) pseudoalloys retaining the α-iron phase is studied. The pseudoalloys with a relative density of 97.5–98.1% are prepared by sintering a powder mixture of the metals reduced from their nanosized oxides. The microstructure of the composites represents a copper matrix with α-iron phase inclusions of about 20–200 nm in size, formed by 6.5–16 nm nanocrystallites. When iron content is 5 and 10%, the composites show matrix microstructure in relation to copper, providing 47–52% electrical conductivity and promoting higher hardness (to 1380 MPa) through precipitation hardening of the copper matrix by iron nanoparticles. The composites acquire matrix-statistical microstructure with increasing iron content.

Structural Changes in Binder During Oxidation of Periclase-Carbon Refractories

Results are given for the change in binder structure in periclase-carbon refractories during heat treatment in an oxidizing atmosphere. After total burn-off at 1000°C carbon, securing periclase grains, the reduction in refractory strength in compression measured at room temperature is 64% of the original, but an object does not disintegrate. An inorganic chemical bond plays the role of a binder consisting of very fine calcium and iron silicates and fine fractions of magnesium, calcium, and iron oxide solid solutions. The results obtained make it possible to predict more reliably the change in refractory properties in service proceeding from the raw material components used.

Radial distribution of iron oxide and silica particles in the reject flow of a spiral concentrator

Spiral concentrators are used in the iron ore industry to separate heavy iron oxide carrier particles from the light silica ones. Losses of iron occur mainly in the fine (−75μm) and coarse (+600μm) size fractions. This paper analyzes the radial distribution of iron oxide and silica particles in the reject of a 7 turn spiral. A splitter divides the reject flow into six (6) streams that can be sampled individually. Results show that coarse iron carrier particles settle mainly in the inner part of the spiral trough. Although fine iron particles are mostly concentrated in the outer part of the spiral trough, a significant proportion of these particles remain captive close to the concentrate ports. Coarse silica particles (+600μm) are not concentrated in the innermost part of the spiral trough, while a significant concentration of silica particles in the size range of 75 to 212μm is found close to the concentrate ports. This observation is coherent with the size of the silica particles that contaminate the spiral concentrate.