Abstract: Iron-containing zinc sulfide concentrate is processed to recover zinc values therefrom. The concentrate is roasted to convert zinc sulfide and iron sulfide to their oxides while adequate sulfide-sulfur is retained to maintain the iron values in the ferrous state and thereby avoid ferrite formation. Zinc oxide and iron oxide values are recovered from the roast, simultaneously or sequentially, and residual zinc sulfide may be recycled to the roasting step.

Abstract: A method of making a ferric oxide burning rate catalyst that results in a highly active, finely divided burning rate enhancing catalyst. An iron-containing compound that is capable of vaporization at a temperature below about 500.degree. C. is vaporized. A mixture comprising the vaporized iron-containing compound is combusted with a gas that is capable of supporting combustion in an oxygen environment and does not condense below about 100.degree. C. The ferric oxide burning rate catalyst made by this process is particulary adapted for use in a composite solid rocket propellant. This process provides an ultra pure, highly active, finely divided burning rate catalyst.

Abstract: Plate-like magnetite particles, plate-like maghemite particles and the processes for producing these particles are herein disclosed. The plate-like magnetite particles and the plate-like maghemite particles provided according to the present invention are fine plate-like particles which are poreless and non-sintered as the plate-like magnetite particles are produced directly from an aqueous solution and these plate-like magnetite particles are oxidized by heating to produce the plate-like maghemite particles. Therefore, these particles can be filled to a high density in a vehicle or resin, have good dispersibility and orientability and are also high in a degree of particle contact, so that they are suited for use as electromagnetic wave absorbing and shielding material, magnetic material for magnetic recording, black or brown pigment for paints and colorant for rubber and plastic products.

Abstract: A highly active, finely divided ferric oxide burning rate catalyst and method for making the same. The catalyst is made by vaporizing an iron-containing compound that is capable of vaporization at a temperature below about 500.degree. C., and is capable of forming ferric oxide when reacted with an oxygen-containing atmosphere at temperatures below about 500.degree. C. The iron-containing compound is then oxidized in an oxygen-containing atmosphere. The ferric oxide burning rate catalyst made by this process is particularly adapted for use in a composite solid rocket propellant. This process provides an ultra pure, highly active, finely divided burning rate catalyst.

Abstract: A crystalline zeolite SSZ-24 is prepared using an adamantane quaternary ion as a template.

Abstract: A crystalline zeolite SSZ-25 is prepared using an adamantane quaternary ammonium ion as a template.

Abstract: A process for producing acicular .alpha.-FeOOH particle powder having a narrow particle size distribution and a rectified shape and being highly dispersed is provided, which process comprises mixing with stirring an aqueous solution of a Fe(II) salt with an aqueous solution of an alkali in an equivalent ratio of alkali to Fe(II) salt of 1.5 or more, oxidizing the mixture with a O.sub.2 -containing gas, heat treating the resulting suspension of iron .alpha.-FeOOH particle powder to 60.degree. to 100.degree. C., further adding an aqueous solution of a FE(II) salt in a proportion of atom to molecule of Fe(II)/.alpha.-FeOOH of 0.5 to 10% and again oxidizing the mixture with a O.sub.2 -containing gas at 35.degree. to 55.degree. C.

Abstract: Very small iron-containing particles that are in the shape of facetted nodules. Such particles can be non-magnetic particles such as delta ferric oxide hydrate particles or magnetic particles such as magnetic iron oxide particles or metallic particles. Magnetic layers containing such magnetic particles combine excellent remanent magnetization with increased output signal level. The facetted nodular particles are prepared in a process in which (a) an aqueous solution of ferrous salt is added to an aqueous solution of alkaline hydroxide while avoiding substantial local excesses of the ferrous salt, and subjecting the ferrous salt solution to reducing conditions before or during its addition to the alkaline hydroxide solution and (b) the ferrous hydroxide particles are oxidized to delta ferric oxide hydrate particles in the presence of an iron complexing agent, for example, pyrogallol, that is capable of selectively forming ferric iron complexes that are soluble in the reaction medium.

Abstract: Disclosed is a process to effect a reduction to a desired, constant degree as exactly as possible and to achieve a low surplus of carbon. The reduction by treatment with carbonaceous reducing agents is effected in such a manner that fine-grained solids, which contain higher metal oxides, are calcined at 800.degree. to 1100.degree. C. with hot gases in which the solids are suspended. The calcined solids are reduced at a temperature in the range of from 800.degree. to 1100.degree. C. to form low metal oxides in a stationary fluidized bed, which is supplied with carbonaceous reducing agents and oxygen-containing gases. The carbonaceous reducing agents are supplied to the stationary fluidized bed at such a rate so as to reduce the higher metal oxides to low metal oxides, while maintaining the reduction temperature in the stationary fluidized bed and insuring that the discharged matter has the desired carbon content.

Abstract: The present invention is a method of producing single, unaggregated magnetic iron oxide particles. An iron or iron and divalent metal halide feed solution is kinetically atomized into a high velocity flame. The feed solution is vaporized and held in a reactor at a temperature and partial pressure of an oxidizing phase sufficient to form either ferrous oxide or magnetite particles. The iron or iron and divalent metal halide vapor reacts with the oxidizing phase vapor and converts to either ferrous oxide vapor or magnetite vapor. Since the vapor phase is beyond equilibrium concentration ferrous oxide or magnetite particles precipitate from the vapor phase. Quenching of the magnetite particles at an enhanced rate to less than 500.degree. C. in a reducing atmosphere renders magnetite and in a oxidizing atmosphere renders maghemite. Quenching of the ferrous oxide particles in a non-oxidizing atmosphere produces magnetite particles.

Abstract: The subject matter of this invention relates to a process for removing the soluble metal cations contained in iron oxide pigments comprising washing said iron oxide pigments with a ligand compound having a pH greater than 6.0. The pigments can be used as colorants for substances ingested by man and animals, and they can also be used to stabilize plastics against ultraviolet degradation, and as pigments in base-coat clear-coat automotive finishing operations.

Abstract: Ultrafine particles of ceramic or metallic material are obtained at low temperatures from a nitrate source capable of endothermic decomposition by molecularly combining under a nitrogen atmosphere the nitrate source with an inorganic reducing fuel compound, such as hydrazine, to provide a chemical precursor for the ceramic or metallic material and then exothermically decomposing the precursor in a controlled atmosphere by heating to a temperature up to about 200.degree. C. below the endothermic decomposition temperature of the nitrate source. The nitrate source is a metal nitrate or a mixture of nitrate salts. Ferrite particles are recovered when the nitrate source is a mixture of nitrate salts containing ferric nitrate in a 2:1 molar ratio with at least one additional metal nitrate.

Abstract: Lepidocrocite (.gamma.-FeOOH) with an large specific surface area and a uniform particle size is provided by a method comprising preparing a suspension of ferrous hydroxide at a pH of 6.5 to 7.5 by adding a ferrous salt solution with an alkali solution in an amount of 0.4 to 0.7 times the theoretical amount for converting all the ferrous salt to ferrous hydroxide, blowing an oxygen-containing gas into the suspension to form a seed crystal of .gamma.-FeOOH, completing the generation reaction of .gamma.-FeOOH by blowing an oxygen-containing gas into the suspension while adding an alkali solution to keep the pH of the suspension within a range of 3 to 5, in which an Si concentration of the suspensions for seed reaction and for generation reaction of .gamma.-FeOOH is controlled to be within 5 to 30 ppm.

Abstract: Efficient, regenerable sorbents for removal of H.sub.2 S from high temperature gas streams comprise porous, high surface area particles. A first class of sorbents comprise a thin film of binary oxides that form a eutectic at the temperature of the gas stream coated onto a porous, high surface area refractory support. The binary oxides are a mixture of a Group VB or VIB metal oxide with a Group IB, IIB or VIII metal oxide such as a film of V-Zn-O, V-Cu-O, Cu-Mo-O, Zn-Mo-O or Fe-Mo-O coated on an alumina support. A second class of sorbents consist of particles of unsupported mixed oxides in the form of highly dispersed solid solutions of solid compounds characterized by small crystallite size, high porosity and relatively high surface area. The mixed oxide sorbents contain one Group IB, IIB or VIIB metal oxide such as copper, zinc or manganese and one or more oxides of Groups IIIA, VIB or VII such as aluminum, iron or molybdenum.

Abstract: Iron is recovered from an iron-containing dust obtained in processing iron or steel by dissolving iron and bivalent metals present in the dust in an acid. Subsequently the iron is precipitated as iron hyroxide by adding an alkaline substance or ammonia to adjust the pH to 5 to 8. Before or during precipitation of any iron the bivalent metal ions present, such as zinc, cadmium and lead, are converted into a soluble complex by the addition of a complexing agent, preferred complexing agents being polyamines, particularly triethylene tetramine. The process may be conducted more than once in the same solution, thereby providing a final solution containing considerable amounts of zinc, cadmium, or other bivalent metals, which may be separated by boiling or precipitation.

Abstract: A process for the preparation of ferrite powders which have a particle fineness which can be set to a defined value, of the general compositionM(II).sub.x Fe(II).sub.1-x Fe(III).sub.2 O.sub.4andM(II).sub.x Fe(III).sub.3-x O.sub.4.5-0.5xwhere M is Mg, Mn, Co, Ni, Cu and/or Zn and x is from 0 to 1, and have an essentially isotropic particle shape.

Abstract: A process for the preparation of finely divided acicular hexagonal ferrites which have a high coercive force and are of the general formula MFe.sub.12 O.sub.19, where M is barium or strontium, and their use for the production of magnetic recording media and plastoferrites.

Abstract: A process for the preparation of finely divided ferrites of the general formulaMeFe.sub.2 O.sub.4 (I)where Me=aMn+bNi+cZn+dCo+eFe(II), and the atomic weight ratios a, b, c, d and e are each from 0 to 1 and their sum is 1, orM.sub.2.sup.1 Me.sub.2.sup.1 Fe.sub.12 O.sub.22 (II)where M.sup.1 is barium, strontium, calcium and/or lead, and Me.sup.1 is divalent manganese, copper, iron, cobalt, nickel, zinc, magnesium and/or equimolar amounts of lithium and trivalent iron, orM.sup.2 (Me.sup.2 Ti).sub.x Fe.sub.12-2x O.sub.19 (III)where M.sup.2 is barium or strontium, Me.sup.2 is zinc, nickel and/or cobalt and x is from 0 to 1.5, wherein the aqueous solutions of the salts required for the particular composition are reacted with an aqueous solution of sodium carbonate and/or potassium carbonate, the water is removed, the dry salt mixture is heated at from 800.degree. to 1200.degree. C., and the resulting finely divided ferrite of the predetermined composition is isolated by leaching with water.

Abstract: A process for the production of ferrous carbonate is provided wherein a mixture of an alkali metal bicarbonate and a ferrous compound such as a ferrous salt in solution is heated to a temperature in the range of about 100.degree. C. to about 300.degree. C. for a sufficient time to allow a precipitate to form. A molar ratio of alkali metal bicarbonate to ferrous compound is at least 2:1, such a ratio giving an extremely pure precipitate of ferrous carbonate.

Abstract: The method of the present invention is a novel comprehensive process for maximizing the recovery of valuable mineral values from coal ash. Options may also be included for the production of saleable inorganic chemical by-products. The process employs both physical and chemical extraction techniques that maximize the yield of products while reducing the quantity of waste produced. Valuable minerals and chemicals such as cenospheres (hollow microspheres), carbon, magnetite (Fe.sub.3 O.sub.4), alumina (Al.sub.2 O.sub.3), iron oxide (Fe.sub.2 O.sub.3) and iron chloride (FeCl.sub.3) may be produced. Due to removal of carbon, magnetite, and iron oxide from the coal ash, the processed ash comprises a quality pozzolan.

Abstract: Ferrimagnetic particles which are useful as magnetic material for magnetic recording media and consist of a core of a magnetic material exhibiting multiaxial anisotropy and a coating which surrounds the core and is composed of a magnetic material possessing uniaxial anisotropy, and a process for their preparation.

Abstract: Chlorine may be recovered from residues from the fluidized bed chlorination of iron-containing metalliferous oxidic materials, such as ilmenite, bauxite, chromite, wolframite, scheelite, tantalite or columbite, the residues containing condensed iron chloride and blow-over bed solids, by heating the residue to revolatalize the iron chloride and reacting it with oxygen. The quantity of iron chloride in the oxidic material is controlled relative to the quantity of blow-over carbon so that the quantity of carbon is sufficient on combustion to provide the required heat but is insufficient to cause undue dilution of the chlorine produced by virtue of its combustion products. Chlorine of a concentration suitable for direct recycle to a chlorination process, e.g. of 30% to 50% volume concentration is produced.

Abstract: In a method of producing a hydrated iron oxide as a starting material for a magnetic powder by aging a suspension of a ferric hydroxide prepared by reacting a ferric salt with an aqueous solution of alkali, the aging temperature is controlled between 20.degree. and 100.degree. C. and pH is controlled between 1 and 6 for the first 5 to 240 minutes while nuclei of hydrated iron oxide crystals generate, and then the aqueous solution of alkali is added again to adjust the pH value to 10 to 13.5 to make the crystals grow. This production method is capable of producing an acicular hydrated iron oxide having a reduced particle-size distribution range and also capable of controlling the length of the crystals as desired.

Abstract: A depot fertilizer composition comprising an inorganic matrix and another inorganic and/or organic component of the formulaX Me(II)O.[(1-x)/2]Me(III).sub.2 O.sub.3.YA.zI.aqin whichMe (II) is at least one divalent metal,Me(III) is at least one trivalent metal,A is at least one inorganic acid or anhydride of an inorganic acid,I is at least one organic compound,aq is 0-9,X is from 0 to 1,Y is from 0.5 to 0.7, andZ is from 0 to 20,at least one of the components containing a plant nutrient element. The compositions are suited for fertilizing the leaves or full systems of plants growing in soil or in water.

Abstract: This invention provides a process for production of a microcrystalline metal oxide having an average particle size less than about 1000 angstroms.An important feature of the invention process involves the application of ultrasonic wave energy during the stage that a solution of metalorganic compounds is being treated to form a gelled solution. The ultrasonic energy input during the gelling stage enhances the production of a high purity metal oxide powder having fine grain particles of uniform microspheric dimensions.

Abstract: Spherical, submicronic, monodispersed, and non-agglomerated particles of metal oxides by reacting with steam a gaseous stream containing an aerosol of liquid particles of a hydrolyzable metal compound. Into a duct, in which an inert gas stream containing vapors of a hydrolyzable metal compound flows, there is fed through a nozzle a cold inert gas stream, the temperatures and flows of the two gaseous streams being such as to establish in the duct a temperature lower than the condensation temperature of the metal compound; the mixed gaseous streams having a turbulent flow in the duct, with a Reynolds number equal to or higher than 1800. At the duct outlet, the aerosol of metal compound liquid particles, which has formed in the duct, is caused to react with steam, wherefore solid particles of hydrated metal oxide form, which are subsequently calcined to the oxide.

Abstract: A process for treating and recovering pickling waste liquids used for the pickling of stainless steel such as nitric-hydrofluoric acid, nitric acid, hydrochloric acid and, sulfuric acid is disclosed, which comprises recovering the nitric-hydrofluoric acid and the iron oxide or metallic ion from the waste liquids of nitric-hydrofluoric acid and nitric acid by two solvent extraction processes and recovering the Cr and Ni containing ferrite from the waste liquids of sulfuric acid or hydrochloric acid by a ferrite formation process. When the waste acid is sulfuric acid, gypsum of a high purity can be obtained.

Abstract: A process for producing magnetic metallic oxide which comprises the steps of pulverizing at least one member selected from the group consisting of ferro-manganese, ferro-nickel, electrolytic manganese, electrolytic iron and electrolytic zinc, adding to the substance thus pulverized at least one member selected from the group consisting of oxides of Fe, Mn, Ni, Cu, Mg, Zn and Co and salts of Fe, Mn, Ni, Cu, Mg, Zn and Co which become oxides by heating, wet pulverizing and mixing the mixture upon oxidation, thereby producing a slurry, and heating said slurry at 800.degree. to 1450.degree. C. By this process, a magnetic ferrite can be stably and inexpensively synthesized.

Abstract: A process for treating iron chloride wastes such as those obtained when chlorinating titanium ore is disclosed. The process involves reacting the iron chlorides with limestone in molten CaCl.sub.2.xH.sub.2 O, where x equals 3-6 and separating the resulting iron oxide from the molten CaCl.sub.2.xH.sub.2 O.

Abstract: A process for the preparation of acicular ferrimagnetic iron oxides by reducing gamma-iron(III) oxide hydroxide to magnetite, at from 280.degree. to 620.degree. C., by means of an organic compound which is decomposable at this temperature in the presence of iron oxide, and, optionally, a stream of reducing gas, and, if desired, then oxidizing the magnetite with oxygen-containing gases, at from 150.degree. to 450.degree. C., to acicular ferrimagnetic iron oxide of the formula FeO.sub.x, where x is from above 1.33 to 1.50, wherein the organic compound used for the reduction is a non-polar glycerol ester of a fatty acid which is introduced into the aqueous reaction suspension during the preparation of the gamma-iron(III) oxide hydroxide.

Abstract: A process for producing acicular magnetite or maghemite of high axial ratio, which comprisespreparing an iron (II) hydroxide suspension at a pH of at least 11 with a magnesium sulfate or magnesium chloride in an amount of 0.5 to 7.0 atomic % based on the amount of the iron (II) hydroxide in the suspension and calculated as the ratio of Mg to Fe (II),oxidizing the resultant suspension with the oxygen-containing gas to form an acicular iron (III) oxide hydroxide in the form of particles having a long axis length of 0.3 to 2.0 .mu.m and an axial ratio of more than 20:1,reducing said acicular iron (III) oxide hydroxide into the acicular magnetite, and oxidizing the resultant acicular magnetite to form the acicular maghemite, if necessary.

Abstract: Acicular ferrimagnetic iron oxides are prepared by a process in which iron (III) oxide hydroxide consisting essentially of lepidocrocite is reduced at from 350.degree. to 600.degree. C. by means of an organic compound which is a synthetic polymer with a molecular weight of from 3,000 to 40,000 to give magnetite, which, if desired, is subsequently partially or completely oxidized with an oxygen-containing gas at from 200.degree. to 450.degree. C.

Abstract: Enhancement of thermal decomposition of solid matter by applying a high voltage but low power electrical field across said solid matter simultaneously with heating of the solid matter.

Abstract: A process for the preparation of finely divided ferrites of the general formulaMeFe.sub.2 O.sub.4 (I)where Me=aMn+bNi+cZn+dCo+eFe(II), and the atomic weight ratios a, b, c, d and e are each from 0 to 1 and their sum is 1, orM.sup.1.sub.2 Me.sup.1.sub.2 Fe.sub.12 O.sub.22 (II)where M.sup.1 is barium, strontium, calcium and/or lead, and Me.sup.1 is divalent manganese, copper, iron, cobalt, nickel, zinc, magnesium and/or equimolar amounts of lithium and trivalent iron, orM.sup.2 (Me.sup.2 Ti).sub.x Fe.sub.12-2x O.sub.19 (III)where M.sup.2 is barium or strontium, Me.sup.2 is zinc, nickel and/or cobalt and x is from 0 to 2.0, wherein the salts required for the particular composition are mixed with sodium carbonate and/or potassium carbonate, the mixture obtained is heated at 700.degree. to 1200.degree. C., and the resulting ferrite is then isolated by leaching with water.

Abstract: A method of producing single crystalline, acicular .alpha.-ferric oxide particles of narrow particle size distribution is provided. The method comprises heating an aqueous suspension of ferric hydroxide at temperatures of 100.degree.-250.degree. C. at an alkaline pH in the presence both a water soluble organic or inorganic compound capable of forming complexes with iron as a growth regulating agent and .alpha.-ferric oxide seed crystals of minor axes not larger than 0.4 microns in average in amounts of 0.1-25 mole % in terms of the Fe content thereof in relation to the ferric hydroxide.

Abstract: A process for stabilizing silica-rich geothermal brine to prevent silica scaling comprises selectively providing a supply of ferric ions, allowing the silica-rich brine to combine with the ferric ions to form insoluble, iron-rich siliceous material and separating the insoluble siliceous material from the brine to form a brine having a silica content which is reduced below the saturation level required for substantially scale-free handling of the brine. In one embodiment of the process in which the brine contains sufficient dissolved ferrous ions, the process comprises selectively contacting the brine with an oxidizing agent, preferably by aerating the brine, to oxidize a selected portion of the ferrous ions to ferric ions, which then combine with silica to form the insoluble iron-rich siliceous material. The ferric ion content of an iron-deficient brine may be augmented by adding ferric and/or ferrous ions to the brine.

Abstract: Synthetic, hexagonal, lamellar iron oxide particles, suitable as corrosion-inhibiting or decorative colored pigments, containing about 0.1 to 12% by weight of at least one oxide of an element of the IVth, Vth or VIth Main and Secondary Groups and of the IInd Secondary Group of the Periodic System of Elements.

Abstract: A method for the production of uniform acicular metal magnetic particles comprising predominantly iron which have excellent magnetic characteristics and are useful as a recording element for a magnetic recording medium, said method comprising the steps of coating the surface of metal compound particles containing predominantly acicular iron oxyhydroxide or iron oxides with at least one member selected from the group consisting of an aluminum compound and a silicon compound, pelletizing the coated particles, and reducing the pellets with heating under reducing atmosphere, e.g. under hydrogen stream.

Abstract: A method of preparing gamma ferric hydroxyoxide in which ferrous ions are reacted in an alkaline solution to produce a suspension of ferric hydroxide, the resulting suspension is treated with an oxidizing gas in a first oxidizing step at a relatively high oxidation rate, sufficient to cause nucleation of gamma ferric hydroxyoxide to occur, and then the oxidation rate is reduced in a second oxidizing step to cause crystal growth to occur on the nuclei formed in the first oxidizing step. The resulting product has magnetic and physical characteristics making it extremely suitable for use in the manufacture of magnetic recording media.

Abstract: A continuous process for obtaining copper from a copper sulfide by:(a) contacting a first batch of the copper sulfide with a first lixiviant containing cupric chloride, and a minimum amount of ferrous chloride to leach copper;(b) separating the leach liquor from (a) from the undissolved solids and dividing the liquor into two portions; one portion of the liquor containing about the same amount of copper as is leached from the copper sulfide in (a) and (f);(c) cementing with iron the copper from the one portion of the liquor from (b);(d) recombining the portions of the liquor from (b);(e) oxidizing with oxygen the recombined portions from (d) to form a second lixiviant; the cuprous chloride therein being oxidized to cupric chloride and the iron therein, from cementing copper, being oxidized and precipitated;(f) contacting the copper sulfide solids from (b) with the second lixiviant from (e) to additionally leach the first batch of the copper sulfide;(g) recycling the leach liquor from (f) to (a) and using it a

Abstract: In a process to produce a synthetic rhombehedral magnetite comprising the steps of:A. Contacting ferrous chloride solution having an Fe.sup.++ concentration of from about 0.9 to 2.4 moles per liter with a stoichiometric amount of carbonate ion;B. heating the mixture to a temperature of from about 70.degree.-90.degree. C.;C. aerating the mixture to oxidize the iron to magnetite having a Fe.sup.++ / total Fe.sup.++ and Fe.sup.+++ ratio of from about 0.25-0.38; andD. recovering the magnetite so produced,the improvement which comprises providing the carbonate in the form of finely divided particles of an average size of less than 3.5 microns.The process wherein said magnetite is calcined at a temperature of from 650.degree.-925.degree. C. in the presence of oxygen to produce alpha ferric oxide is claimed and a synthetic rhombohedral magnetite having a BET surface area of greater than about 13 m.sup.2 /g and an average particle size of less than about 0.08 microns as measures along the long axis is also claimed.

Abstract: This disclosure relates to a process for preparing acicular magnetic iron oxide particles by (a) adding an aqueous solution of a ferrous salt to an aqueous solution of a stoichiometric excess of alkaline hydroxide while substantially avoiding local excesses of the ferrous salt, to form an aqueous dispersion of ferrous hydroxide particles, (b) oxidizing these particles to form non-magnetic alpha ferric oxide hydrate particles, and (c) converting the non-magnetic particles to magnetic iron oxide particles by dehydration and reduction or dehydration, reduction and oxidation. The ferrous salt solution is subjected to reducing conditions prior to and/or during the addition to the alkaline hydroxide solution to reduce contaminating ferric ions that are normally present to ferrous ions.

Abstract: A process for the manufacture of acicular ferrimagnetic iron oxide by heating iron(III) oxide or iron(III) oxide hydroxide at 220.degree.-460.degree. C. under a water vapor partial pressure of not less than 30 mbar, reducing the resulting product to magnetite by means of hydrogen and/or CO and/or an organic compound which can decompose in the presence of iron oxide, and then oxidizing the magnetite with an oxygen-containing gas to give acicular ferrimagnetic iron oxide of the formula FeO.sub.X, where X is from 1.33 to 1.50.

Abstract: Substantially dry iron oxide particles having a high surface area, a high kinetic "K" value and composed of a crystalline phase of Fe.sub.3 O.sub.4 together with an amorphous Fe.sub.2 O.sub.3 moiety or portion and having a surface area of at least 4 m.sup.2 /.sub.g are useful for scavenging hydrogen sulfide from other gases containing it. A cartridge type device is provided containing such particles intermixed with inert particulate matter, e.g. sand, useful as a means for scavenging hydrogen sulfide from such other gases.

Abstract: The removal of silica from an iron-bearing source which is treated to produce an iron powder which may be used in powder metallurgical applications may be facilitated by subjecting the reduced iron-bearing source such as magnetite to a sparge with an oxygen-containing gas such as oxygen or air prior to a caustic leach step. The sparge of the caustic-magnetite slurry is effected at ambient temperatures and pressures which may range from about 10 to about 1000 psi for a period of time ranging from about 0.1 to about 1 hour. By utilizing this sparge, the leaching capacity of the caustic leach solution appreciably increased.

Abstract: In the production of needle-shaped magnetic iron oxide pigments by treating iron with a nitro-aromatic in the presence of .alpha.-FeOOH nuclei to form .alpha.-FeOOH particles and an amino-aromatic, and thereafter dehydrating the .alpha.-FeOOH particles and reducing them, the improvement which comprises forming the .alpha.-FeOOH nuclei at about 0.degree. to 90.degree. C. in a suspension of metallic iron, an iron-(II)-salt and a nitro-aromatic by adding a basic precipitant in about 10 to 95% of the amount required for the complete precipitation of the iron in the iron-(II)-salt. Advantageously the metallic iron comprises cast iron, the nitro-aromatic comprises nitrobenzene, the amino-aromatic comprises aniline, the basic precipitant comprises at least one of ammonia and a basically reacting alkali metal, alkaline earth metal or ammonium salt, the nuclei formation is carried out at about 10.degree. to 60.degree. C.

Abstract: Acicular hydrated ferric oxide particles are produced by premixing an aged ferric hydroxide with a newly formed ferric hydroxide or a mixture of ferrous hydroxide and an oxidizing agent and treating the pre-mixture by a hydrothermal reaction of said pre-mixture at 100.degree. to 250.degree. C.

Abstract: H.sub.2 S is removed from a stream of gas such as coal gas at a relatively elevated temperature (300.degree.-400.degree. F.) in a process which employs sulfates or hydroxides of nickel, iron, or zinc as sulfur absorbents. The absorbents are converted to metal sulfides during the absorption process and are regenerated by aeration. Acids produced during sulfur absorption and absorbent regeneration steps are neutralized through the addition of a base. In a preferred embodiment ammonia is also removed and elemental sulfur is produced during the process.

Abstract: There is disclosed a process for producing yellow iron oxide pigment which comprises the precipitation of the yellow iron oxide pigment by the addition of a soluble metal carbonate in the presence of oxygen to a solution of a soluble ferrous salt wherein the pH of the reaction system is maintained at a value of approximately 4 or less during the precipitation reaction.

Abstract: In a process for producing an iron oxide having magnetite as a main component by heating to reduce a powder of an iron oxide or a hydrated iron oxide in an atmosphere for reduction, an improvement characterized in that said atmosphere for reduction comprises an inert gas, steam and a gas of an organic compound for reducing an iron oxide.