Abstract: The invention relates to a method for producing magnetite with a purity of no less than 90% and higher than 98%, by oxidation of pulverized wustita (iron oxide), at temperatures ranging from 200° C. to 800° C., with the addition of water in liquid or steam form, in counter-current or concurrently, in an externally heated reaction chamber with a controlled atmosphere. The amount of water used to oxidize the wustita being 60 to 500 ml per kilogram of wustita, the grains of wustita powder injected into the reaction chamber having a size no greater than 100 ?m for optimal reaction.

Abstract: A method for magnetic ore separation and/or dressing is provided, in which metalliferous recoverable materials are separated from conveyed metalliferous ore rock.

Abstract: A production process for an oxide magnetic material comprising the steps of blending raw material powder so as to take the composition of a hexagonal ferrite including: at least one kind of an element A selected from the group consisting of Ba, Sr and Ca; Co and Cu; Fe; and O; and sintering said blended powder at a temperature lower than 1000° C.

Abstract: Methods and apparatuses for separating metal values, such as nickel and nickel compounds, from mineral ores, including lateritic ores are disclosed. The method includes providing a mixture of particles (e.g., crushed and sized ore) that is composed of at least a first group of particles and a second group of particles. Group members have similar chemical composition, while particles belonging to different groups have dissimilar chemical compositions. The mixture of particles is exposed to microwave/millimeter wave energy in order to differentially heat the first and second group of particles, thereby increasing differences in magnetic susceptibility between the first and second group of particles. The mixture of particles is then passed through a magnetic field gradient, which causes the particles to separate into magnetic and non-magnetic fractions.

Abstract: Coloring pigment of comparable quality to, and cheaper than, pigments products by chemical precipitation, is made from synthetic magnetite produced by oxidation of ferrous mill scale and reduced to a particle size such that preferably at least 85% of the product does not exceed 10 microns and 95% does not exceed 20 microns. The smaller the particle size the greater the tinting strength of the pigment. The pigment may be black or, by calcination of the synthetic magnetite, it may be red. For best quality the black pigment should contain 95-99.5% iron oxides, typically, and the magnetite should have a molecular ratio of 0.9 to 1.1:1. The shade and hue of red is dependent upon the calcination temperature and final size and shape of the particles. Reduction to the required particle size for the red coloring pigment may be done before and/or after calcination.

Abstract: A process for the preparation of ferromagnetic metallic particles for magnetic recording which comprises(I) a step of preparing a slurry of acicular iron oxide hydrate containing nickel and, if necessary, manganese,(II) a step of coating the surface of the above iron oxide hydrate with aluminum-containing iron oxide hydrate, thus giving a slurry containing the coated iron oxide hydrate and free aluminate ions,(III) a step of depositing aluminum and phosphorus and/or silicon on the outside surface of the aluminum-containing iron oxide hydrate, thereby giving a slurry of the iron oxide hydrate thus treated,(IV) a step of subjecting the slurry to washing, drying and dehydrating, reducing the obtained particles, and forming an oxide layer on the surface of the reduced particles.

Abstract: A method for increasing the magnetization of pyrite-containing pulverized coal comprises heating the coal in an atmosphere of inert gas, desirably nitrogen, containing 3 to 60 torr, preferably 12 to 16 torr, partial pressure of air to a temperature in the range 390.degree. to 455.degree. C., desirably 400.degree. to 410.degree. C., for a time sufficient, preferably 2 minutes to 2 hours, for converting enough pyrite to magnetite to allow separation of at least 50% by weight of the pyrite from the coal in a low-strength magnetic field. The sulfur content of coal treated in accordance with this method can be reduced by subjecting the treated coal to a low-strength magnetic field for moving at least 50% by weight of the pyrite from the coal although a smaller fraction, about 5 to 25%, of the pyrite is actually converted to magnetite.

Abstract: A method of recovering copper and nickel from sulphidic minerals containing copper, nickel and iron comprises the steps of roasting the mineral, preferably to provide magnetite; sulphating, for example with sulphuric acid, sulphur trioxide, metal sulphate and/or sulphur dioxide together with oxygen; and a subsequent leaching of the sulphated material and recovery of copper from the leaching solution, for example by electrolysis. All or part of the leaching solution with its nickel content is recycled to the roasting stage, and the nickel content is removed in the form of nickel oxide together with the leaching residue, from which nickel can be recovered.

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 method of treating pyrite bearing polymetallic material comprises heating the material in an atmosphere of reducing gases at a temperature of 450.degree. to 500.degree. C. for a period of 30 to 60 min.Gases such as hydrogen, or products of conversion of natural gas or mazut can be used to provide the reducing atmosphere.The roasted copper-containing material is cooled at a rate of 2 to 4 deg. per min and is then subjected to magnetic separation.The operation of magnetic separation is carried out in two stages with the intensity of the magnetic field ranging from 1000 to 2000 oersted, whereafter copper sulphides are removed from the roast, with a magnetic field intensity ranging from 4500 to 6000 oersted.

Abstract: A method comprises heating the material to be treated without access of air at a temperature of 700.degree. to 800.degree. C. for a period of 1-2 hours, and then subjecting this material to subsequent magnetic separation.It is advisable that the furnace walls surrounding the material under treatment be heated to a temperature which is 100.degree. C. to 200.degree. C. higher than the boiling temperature of the volatile components of the material. Upon completion of the heating operation, the material being treated is cooled at a rate of 2 to 4 deg. per minute, whereafter iron sulphides are removed therefrom by means of magnetic separation, the intensity of magnetic field ranging from 1000 to 2000 oersted, and then copper sulphides are separated, with the field intensity ranging from 4500 to 6000 oersted.

Abstract: Recovery of cobalt and manganese metal oxidation catalysts from residue of trimellitic acid manufacture and separation of recovered cobalt from recovered manganese can be accomplished by a novel method involving dissolving the residue in water, displacing dissolved cobalt as cobalt metal by manganese metal added to the solution whose pH has been adjusted to pH of 6 and then using magnetic means for separating metallic cobalt from the cobalt-free solution.

Abstract: This invention relates to a process for separating rutile and ilmenite from ilmenite leach tails and is effected by treating the leach tails from an acidic leach to a flotation step whereby gangue is separated from the unreacted ilmenite and rutile. The latter is then roasted at an elevated temperature in a hydrous atmosphere to convert the ilmenite to a magnetic material. Thereafter the ilmenite may then be subjected to a magnetic separation whereby non-magnetic rutile may be recovered while the magnetic portion is recycled for further separation.

Abstract: High purity iron powder may be obtained by treating an iron bearing source which contains impurities such as silica along with minor amounts of aluminum, calcium and magnesium to a series of steps which include grinding the iron bearing source followed by subjecting the ground source to a caustic leach at an elevated temperature and pressure. Thereafter the soluble impurities may be separated from the residue, the latter then being reduced by treatment with hydrogen at an elevated temperature and pressure to convert the iron to the metallic form.

Abstract: Ammonium jarosite is converted to hematite or magnetite and ammonium sulphate. The invention can be used for removing iron from a feed solution containing dissolved ferrous sulphate. The feed solution is treated with ammonium sulphate and oxygen to precipitate ammonium jarosite which is then separated from the treated solution to produce an ammonium jarosite slurry and a separated solution containing sulphate ions. The ammonium jarosite slurry is treated with ammonia to convert the ammonium jarosite to hematite or magnetite and ammonium sulphate solution. The ammonium sulphate solution is separated from the hematite or magnetite, and a portion of the separated ammonium sulphate solution is recycled to the ammonium jarosite precipitation step, the remaining portion of the separated ammonium sulphate solution being recovered.

Abstract: Gypsum and magnetite which are both coarse and of good quality can simultaneously be produced by introducing calcium carbonate into an aqueous solution containing ferrous sulfate while an oxidizing gas is blown, and then carrying out a neutralizing and oxidizing operation at a pH of 5-6 and a temperature of 60-80.degree. C, and can be separately recovered by magnetic separation.

Abstract: A metallic iron-containing starting material such as iron filings, iron powder or a reduced ore such as ilmenite is oxidized with air in the presence of 5 to 40% of iron oxide and/or iron oxide hydroxide nuclei and about 2.5 to 200% of an electrolyte, percentages being based on metallic iron by weight. The oxidation is effected in aqueous suspension at 75.degree. to 100.degree. C and a pH of 4 to 6.5. If the nuclei are magnetite-free, at least the first quarter of the oxidation should be at pH 5 to 6.5. Preferred electrolytes are transition metal salts. The pigments are more intense in color and have a more pronounced blue tinge.

Abstract: A process is disclosed for preparing magnetite having an equiaxial morphology and a narrow particle size dispersion by precipitation from a ferrous sulphate solution, characterized in that:A. during a first step, at a temperature between 15.degree. and 40.degree. C, alkali is added to the ferrous sulphate solution, in a stoichiometric amount adapted to precipitate, in the form of ferrous hydroxide, 2/3 of the Fe.sup.+.sup.+ ion, and then, at the conclusion of said precipitation, air is blown thereinto thus oxidizing ferrous hydroxide to goethite .alpha.FeO(OH); andB. during a second step, alkali is added to the slurry obtained in the first step, the remaining Fe.sup.+.sup.+ is precipitated in the form of ferrous hydroxide, and the slurry is heated to a temperature between 70.degree. and 100.degree. C, thus causing the formation of magnetite which is then separated from the solution.

Abstract: A process is disclosed for producing magnetite having an equiaxial morphology in the state of a hyperfine powder, starting from a solution of a bivalent iron solution, characterized in that:A. an aqueous suspension of Fe(OH).sub.2 is prepared by reacting an aqueous solution of a ferrous salt with alkali;B. said aqueous suspension of Fe(OH).sub.2 is fed into an autoclave into which is also introduced a quantity of air corresponding to 4-15 normal liters per 100 g of bivalent Fe; andC. the autoclave is then brought to a temperature between 150.degree. and 200.degree. C and maintained at this temperature until the inside pressure has stabilized itself at a constant level, thereby bringing about the formation of the desired magnetite which, once discharged from the autoclave, is washed and dried. The aqueous suspension of Fe(OH).sub.2 subjected to thermal decomposition in the autoclave may have present therein Cu.sup.+.sup.+ion, in a quantity between 0.3 and 1.4% by weight of the bivalent Fe. When Cu.sup.+.sup.

Abstract: A method is disclosed for controlling the particle size of equiaxial magnetite obtained by a process for preparing same starting from ferrous sulphate solutions, characterized in that the reaction forming the magnetite is conducted in a suspension to which .gamma. FeO(OH) has been added in such an amount that Fe of the .gamma. FeO(OH) is 0.1-10% of the Fe.sup.+.sup.+ initially present in the solution.