A process disclosed herein is related to the isolation and purification of substantially pure chemicals, including silica gel, sodium silicate, aluminum silicate, iron oxide, and rare earth elements (or rare earth metals, REEs), from massive industrial waste coal ash. In one embodiment, the process includes a plurality of caustic extractions of coal ash at an elevated temperature, followed by an acidic treatment to dissolve aluminum silicate and REEs. The dissolved aluminum silicate is precipitated out by pH adjustment as a solid product while REEs remain in the solution. REEs are captured and enriched using an ion exchange column. Alternatively, the solution containing aluminum silicate and REEs is heated to produce silica gel, which is easily separated from the enriched REEs solution. REEs are then isolated and purified from the enriched solution to afford substantially pure individual REE by a ligand-assisted chromatography. Additionally, a simplified process using one caustic extraction and one acidic extraction with an ion exchange process was also investigated and optimized to afford a comparable efficiency.

Provided is an ε-iron oxide type ferromagnetic powder with a powder pH within a range of 4.8 to 6.8; and a method for manufacturing the ε-iron oxide type ferromagnetic powder and a composition containing at least the ε-iron oxide type ferromagnetic powder and a solvent.

Provided is an ε-iron oxide type ferromagnetic powder with a powder pH within a range of 4.8 to 6.8; and a method for manufacturing the ε-iron oxide type ferromagnetic powder and a composition containing at least the ε-iron oxide type ferromagnetic powder and a solvent.

A method for simultaneously preparing an iron oxide red pigment and an aromatic amine is provided. In the method, an aromatic nitro compound and ferrous iron are first used to prepare an iron oxide red seed crystal under the action of a catalyst, and then iron powder is used to reduce the aromatic nitro compound and generate iron oxide in situ which grows into iron oxide red with pigment performance on the seed crystal. The method provides a clean and economical way for the reduction of an aromatic nitro compound (especially those in which there are other easily-reduced substituents on an aromatic ring) to prepare an aromatic amine.

A method for simultaneously preparing an iron oxide red pigment and an aromatic amine is provided. In the method, an aromatic nitro compound and ferrous iron are first used to prepare an iron oxide red seed crystal under the action of a catalyst, and then iron powder is used to reduce the aromatic nitro compound and generate iron oxide in situ which grows into iron oxide red with pigment performance on the seed crystal. The method provides a clean and economical way for the reduction of an aromatic nitro compound (especially those in which there are other easily-reduced substituents on an aromatic ring) to prepare an aromatic amine.

Disclosed is a method for producing deposition particles or intermediate particles, characterized in that the method comprises: forming a solution comprising a solvent and one or more deposit sources, aerosolizing the formed solution to produce an aerosol of precursor particles comprising the deposit source, conditioning the precursor particles to produce deposition particles or intermediate particles from the deposit source and collecting said particles. The particles may be collected as a deposit or precursor deposit on a substrate. The particles may include a matrix material and a dopant. The conditioning may be quenched to produce a desired substructure. The matrix material may be essentially optically clear. The substrate may comprise an optical fiber or an optical fiber preform or mandrel.

Disclosed is a method for producing deposition particles or intermediate particles, characterized in that the method comprises: forming a solution comprising a solvent and one or more deposit sources, aerosolizing the formed solution to produce an aerosol of precursor particles comprising the deposit source, conditioning the precursor particles to produce deposition particles or intermediate particles from the deposit source and collecting said particles. The particles may be collected as a deposit or precursor deposit on a substrate. The particles may include a matrix material and a dopant. The conditioning may be quenched to produce a desired substructure. The matrix material may be essentially optically clear. The substrate may comprise an optical fiber or an optical fiber preform or mandrel.

The invention provides a core-shell particle which can provide, by being calcinated, epsilon type iron oxide-based compound particles that have a small coefficient of variation of primary particle diameter and show excellent SNR and running durability when employed in a magnetic recording medium as well as applications thereof. The core-shell particle includes: a core including at least one iron oxide selected from Fe.sub.2O.sub.3 or Fe.sub.3O.sub.4, or iron oxyhydroxide; and a shell that coats the core, the shell including a polycondensate of a metal alkoxide and a metal element other than iron, as well as applications thereof.

The invention provides a core-shell particle which can provide, by being calcinated, epsilon type iron oxide-based compound particles that have a small coefficient of variation of primary particle diameter and show excellent SNR and running durability when employed in a magnetic recording medium as well as applications thereof. The core-shell particle includes: a core including at least one iron oxide selected from Fe.sub.2O.sub.3 or Fe.sub.3O.sub.4, or iron oxyhydroxide; and a shell that coats the core, the shell including a polycondensate of a metal alkoxide and a metal element other than iron, as well as applications thereof.

Provided is an iron oxide powder for a brake friction material which can be suitably used in a brake friction material that is less likely to cause problems regarding brake squealing and that provides superior braking performance. The iron oxide powder for a brake friction material according to a first embodiment of the present invention is characterized by having a sulfur content of 150 ppm or less as measured by combustion ion chromatography, and a saturation magnetization of 20 emu/g or less. The iron oxide powder for a brake friction material according to a second embodiment of the present invention is characterized by having an average particle size of 1.0 μm or more, a chlorine content of 150 ppm or less as measured by combustion ion chromatography, and a saturation magnetization of 20 emu/g or less.