Showing papers on "Iron oxide published in 1979"

Semiconductor Properties of Iron Oxide Electrodes

Abstract: The semiconductor electrode properties of thermally grown iron oxide and anodic oxide films on iron are compared. The bandgaps are 2.1 and 1.9 eV, respectively. Donor densities and flatband potentials are reported. Measurement of the currents produced by chopped illumination has allowed evaluation of electrode parameters and determination of reaction pathways.

Mössbauer effect and magnetic studies of secondary iron oxides in soils

Abstract: Summary Simple, rapid and non-destructive measurements of magnetic properties (magnetic susceptibility, saturation isothermal remanent magnetization and coercivity of isothermal remanence) coupled with more time consuming and sophisticated analyses such as thermomagnetic and Mossbauer effect studies, provide a basis for identifying forms of iron oxide present in the soil. At two of the sites studied, Caldy Hill, Merseyside, and Llyn Bychan, N. Wales, the secondary ferrimagnetic oxide formed in surface soil as a result of recent forest fires is shown to be non-stoichiometric magnetite approximating to the formula Fe2. 904. No evidence for the presence of maghemite was found in any of the soil samples from these sites or in soils from the Annecy region of S.E. France.

Mottling and Iron Distribution in a Glossoboralf-Haplaquoll Hydrosequence on a Glacial Moraine in Northwestern Wisconsin1

Abstract: Distribution of iron oxide and forms of mottling and cutans under various moisture regimes were studied in a Woodfordian glacial moraine landscape. Hydrosequence members were observed and sampled along two transects in adjacent first-order drainage basins. Considerable iron had been translocated out of the A horizon and either into the B horizon or out of the solum, in all pedons studied. Mottle development followed an expected systematic sequence from none at well-drained (WD) sites, where unsaturated movement of water predominates; to considerable at somewhat poorly drained (SPD) sites, where saturated flow occurs frequently and where the dry-wet cycle is characteristic; to few at very poorly drained (VPD) sites where gleying has been favored by stagnant water conditions in wet seasons. At WD sites mottles were either absent or of low chroma both in the interiors and on the faces of peds. At SPD sites mottles were of low chroma on ped faces and of high chroma inside peds, and Fe-Me concretions were relatively abundant. At VPD sites neutral gray hues predominated both inside peds and on surfaces of macrospores, and there were only a few iron concretions or, at wettest sites, “pipestems.” Changes in distribution of iron extractable by aqua regia, dithionite and oxalate characterized the degree of crystallinity of iron compounds in the sequence. Iron oxides were most crystalline at WD sites where they tended to concentrate in the clay fraction. Iron oxides were concentrated in sand-size concretions at SPD sites.

Method for producing molten iron by submerged combustion

Abstract: A method and apparatus for reducing particulate iron oxide and producing molten iron in which coal and oxygen are injected into a molten iron bath to melt the iron, gasify the coal and produce a hot off-gas which is then used as the reductant in a counterflow shaft furnace to reduce iron oxide pellets and/or natural ore in a continuous manner. The hot reduced iron product from the shaft furnace is discharged directly into the molten iron bath from which the molten iron product is discharged.

Decomposition of jarosite

Abstract: Precipitation of iron as a jarosite is used in various hydrometallurgical processes. There are several advantages to this route, for example excellent liquid-solid separation characteristics, selective precipitation of iron in environmentally more stable form, recovery of sulfur as sulfuric acid and higher zinc extraction. However, jarosite precipitation also has disadvantages, the major being the high cost of reagents. A laboratory study was therefore carried out on the conversion of ammonium jarosite to iron oxide with recovery of reagents as byproducts. The investigation resulted in the development of three process possibilities: 1) thermal decomposition with separate recovery of hematite, ammonia and sulfur dioxide, 2) decomposition of jarosite in an aqueous slurry to hematite and ammonium sulfate, or 3) decomposition in an aqueous slurry to magnetite and ammonium sulfate. The conditions affecting the decomposition of jarosite by all three methods have been defined and the chemical, mineralogical and physical characteristics of the iron products are identified.

Ferromagnetic resonance of spherical particles of α‐iron precipitated in fused silica

Abstract: Ferromagnetic resonance (FMR) spectra were obtained at 9 and 35 GHz for particles of metallic iron precipitated in fused silica containing 1–120 ppm Fe. Accurate g values and anisotropy constants K1, K2 and K3 were extracted by computer simulation of the powder pattern line shapes, assuming negligible shape anisotropy. One sample, melted under a He‐H2O atmosphere, exhibited anisotropy constants identical with published values for pure α–iron and a g value of 2.081±0.002. Samples strongly reduced in H2 displayed smaller values of K1, consistent with expectation for alloying of the Fe with up to 20% Si. These K1 values were shown to be statistically distributed and linearly correlated with the g values in the range 5?at.%Si?20. All samples displayed increases ∼ 5–10% in apparent K1 value with increasing frequency, either as‐delivered or after aging. It is hypothesized that the latter effects are due to the formation of a magnetic iron oxide layer at the metal‐glass interface.

The effects of organic matter, iron oxides and moisture on the color of two agricultural soils of quebec

Abstract: A new spectrophotometric interpretation of the influence of organic matter, iron oxides and moisture on the soil color of the Ste-Sophie sand and the Ste-Rosalie clay is reported. The method is based on calculation of the area ratio of the reflected (area under the reflectance curve) against the absorbed (area over the reflectance curve). The higher the ratio the lighter is the soil. After treatment to remove organic matter and iron oxide coatings, both soils presented colors significantly lighter than those observed in untreated soils. Organic matter and amorphous iron oxide contributed for 78% and 64% of the color in the Ste-Sophie sand and in the Ste-Rosalie clay, respectively. Moisture tends to mask the effects of organic matter and iron oxides on soil color. Air-dried soils when compared to moistened soils were lighter in color.

Ferrite powder type magnetic toner used in electrophotography and process for producing the same

Abstract: A ferrite powder type magnetic toner used in an electrophotography. It comprises a resinous component and a ferrite having a spinel structure comprising components of iron oxide at a ratio of 99.9 to 51 mole % as Fe2 O3 and at least one metal oxide selected from the group consisting of manganese oxide, nickel oxide, cobalt oxide, magnesium oxide, copper oxide, zinc oxide and cadmium oxide at a ratio of 0.1 to 49 mole % as MO wherein M represents Ni, Co, Mg, Cu, Zn or Cd.

Generation and use of three types of iron-oxide aerosol.

Abstract: Three distinct submicrometric aerosols of iron oxide can be reproducibly generated by combustion of iron pentacarbonyl vapors under varying conditions. Each aerosol was sized with a concentric aero...

Amorphous transition metal oxide films

Abstract: We have been able to prepare amorphous oxides of Fe and Cr by sputter deposition. Magnetization measurements were made between 4.2 K and 300 K. Mossbauer spectra were obtained for the iron oxide samples in the same temperature range. Amorphous CrO2 films showed no evidence of magnetic order. For the amorphous Fe oxide films, the 4.2 K Mossbauer spectrum showed a broad symmetric six line pattern which collapsed to a doublet at T?100 K. The susceptibility of amorphous iron oxide shows a broad maximum near T=100 K and a paramagnetic moment of only 3μβ. We present arguments that this behavior cannot be described by superparamagnetism and therefore represents the intrinsic magnetic behavior of amorphous iron oxide.

Apparatus for direct reduction of iron using high sulfur gas

Abstract: A method and apparatus for the direct reduction of iron oxide utilizing sulfur-containing gas such as coke oven gas for the process gas. Sulfur-containing gas is heated and injected above the reduction zone to transfer the sulfur to the hot burden. The apparatus includes an upper bustle zone for prereduction and sulfur transfer and a lower bustle zone for the final reduction of the burden to metallized iron.

Study of iron oxide surface by adsorption and temperature-programmed desorption

Abstract: Catalytic sites on an iron oxide surface, active in the selective oxidation of butene to butadiene, were studied by adsorption and temperature-programmed desorption of cis-2-butene, butadiene, and carbon dioxide. Three distinct types of sites were identified: isomerization site, selective oxidation site, and combustion site. Results indicate that the three sites are independent of each other. Interaction of hydrocarbons was the weakest with the isomerization site, and strongest with the combustion site. Desorption from the oxidation sites can be identified. By quantitatively determining the desorption products in the adsorption of cis-2-butene and butadiene, concentrations of th selective oxidation and the combustion sites were estimated. 8 figures, 4 tables.

Coating iron oxide particles for magnetic recording

Abstract: In the preparation of highly orientatable needle-shaped ferrimagnetic iron oxide particles by the reduction and reoxidation of needle-shaped particles of hydrated oxide of iron which have been surface treated against sintering the improvement which comprises effecting the surface treatment by applying to the particles of hydrated oxide of iron one layer of oxygen-containing anions and a further layer of polyvalent cations, each layer weighing about 0.02 to 2% by weight of the particle. Advantageously, the polyvalent cation-containing layer is applied between two oxygen-containing anion layers, the oxygen-containing anions used are selected from the group consisting of silicate, phosphate, borate, vanadate, molybdate and tungstate, the polyvalent cations used are selected from the group consisting of aluminum, chromium, manganese, iron and gallium, each layer weighs about 0.1 to 1% of the weight of the particles and before the reduction and reoxidation the surface treated particles of hydrated oxide of iron are tempered at a temperature of about 600° to 900° C.

Process for scavenging hydrogen sulfide from hydrocarbon gases

Abstract: A process for scavenging hydrogen sulfide from hydrocarbon gases utilizes iron oxide particles of unique chemical and physical properties. These particles have large surface area, and are comprised substantially of amorphous Fe 2 O 3 containing a crystalline phase of Fe 2 O 3 , Fe 3 O 4 and combinations thereof. In scavenging hydrogen sulfide, the iron oxide particles are suspended in a liquid which enters into intimate mixing contact with hydrocarbon gases; the hydrogen sulfide is reacted at an exceptional rate and only acid-stable reaction products are formed. Thereafter, the sweetened hydrocarbon gases are collected.

Azide and doped iron oxide gas generating composition

Abstract: A nitrogen gas generating composition is provided which consists of a stoichiometric mixture of an alkali metal azide or an alkali earth metal azide and a doped iron oxide of high chemical reactivity. The doped iron oxide contains up to 1.0% by weight of another metal oxide impregnated into its particle lattice. The resulting composition has improved properties of ignition delay time, total burn time, filter-ability and reduced toxic by-products.

Laboratory simulations of the pyrolytic release experiments - An interim report

Abstract: During its operation on Mars the pyrolytic release experiment (PR) detected the fixation of small amounts of CO2 and/or CO. Laboratory simulations of the experimental conditions were made in an attempt to substantiate the previous conclusion that these reactions were chemical rather than biological. The selection of model substrata for these tests was based on the known properties of the Martian surface material. After pretreatment and incubation under various conditions, pyrolytic analysis was used to indicate the extent of surface catalyzed conversion of14CO2 or14CO to14C-organic compounds. This abiotic synthesis was detected in experiments with three iron oxides, viz. hematite, magnetite and maghemite. When the incubation atmosphere was supplemented with water vapor, the levels of synthesis were in a range comparable to that detected in the Viking PR tests. An abiotic synthesis was also detected in experiments with a mixture of clays and minerals (Mars analog soil) or with montmorillonite artifically enriched in iron. With either substratum the reaction appeared to be the result of a photocatalytic synthesis of14C-organics from14CO and surface hydroxyl groups. This process was not dependent on the presence of water vapor in the incubation atmosphere. Although a duplication of the Viking data has not been achieved, these findings support the abiotic interpretation of the PR results.

A new approach to the synthesis of cobalt modified iron oxide

Abstract: The new approach to the synthesis of cobalt modified iron oxide with an autoclave in a hydrogen atmospher is reported. The acicular particles of magnetite used for this technique are the following three kinds: (1) The magnetite made by usual preparation method. (2) The magnetite made from goethite whose surface was treated with SiO 2 . (3) The magnetite obtained by annealing of the magnetite in (2). The product has a black acicular crystalline structure. The analysis of magnetic measurements proved that the surface localization of cobalt compounds is very important in order to improve the magnetic stability.

Method for producing molten iron from iron oxide with coal and oxygen

Abstract: A method and apparatus for reducing particulate iron oxide and producing molten iron in which coal and oxygen are impinged onto a molten iron bath in a closed vessel to melt the iron and gasify the coal. The hot off gas from the vessel is removed and used as the reductant in a counterflow shaft furnace to reduce iron oxide pellets and/or iron ore in a continuous manner. The hot reduced product from the shaft is discharged directly into the molten iron bath and melted.

Iron Oxide Deposition on Heated Surfaces in Pressurized Boiling Water

Abstract: The deposition of suspended iron oxide in water at a 10-atm pressure during nucleate boilings on a Zircaloy heated surface has been studied. The effects of pressure on the deposition rate d...

Cancer incidence and exposure to iron oxide dust.

Abstract: Iron oxides, particularly hematite, have been suspected for carcinogenic properties based on epidemiological observations and experimental data. This case-control (case-referent) study concerns a worker population with high exposure to dust of iron oxides, particularly hematite, and with some impurities of pentavalent arsenic and other metals. In spite of the high exposure levels no excess of cancer has been observed, either in the respiratory system or at other sites. It is suggested that earlier findings of respiratory cancers as possibly associated with iron oxides exposure might rather be due to other concomitant risk factors.

Process for producing metallized iron pellets

Abstract: Highly metallized, non-pyrophoric pellets are produced from a finely-divided iron ore concentrate by preparing a moistened mixture of the ore concentrate, a finely-divided carbonaceous material in an amount at least sufficient to reduce all the iron oxide to metallic iron, about 1 to about 30 weight % of a bonding agent, such as burned or hydrated lime, and 0 to up to about 3 weight % of a siliceous material (as available SiO 2 ), such as silica, forming green pellets from this mixture, drying the green pellets to a moisture content of 5% or less, hydrothermally hardening the dried, green pellets by contacting them with steam under pressure, and metallizing the hardened pellets by tumbling them in a reduction furnace, such as a rotary kiln, at a reduction temperature of about 1033° C. up to the melting point of the metallized pellets and in the presence melting point of the metallized pellets and in the presence of a substantially non-oxidizing atmosphere for a sufficient time to reduce a substantial portion of the iron oxide therein to metallic iron. In a preferred embodiment, a charring coal is fed into the rotary kiln along with the hardened pellets and is charred during pellet metallization. The resulting char, after separation from the metallized pellets and comminution, is recycled for use as the carbonaceous material in the starting mixture.