An object of the present invention is to provide magnesium oxide for an annealing separator which is useful for obtaining grain-oriented electromagnetic steel sheets with excellent magnetic properties and insulating properties. To resolve the above object, an aspect of the present invention resides in magnesium oxide for an annealing separator which has an adhesion water content and a hydration water content each falling in the quadrilateral region defined by the following points a to d as the vertices in a graph representing the adhesion water content-hydration water content relationship: a: adhesion water content: 0.25 mass %, hydration water content: 0.1 mass % b: adhesion water content: 0.60 mass %, hydration water content: 0.1 mass % c: adhesion water content: 0.40 mass %, hydration water content: 6.0 mass % d: adhesion water content: 0.20 mass %, hydration water content: 6.0 mass %.

An object of the present invention is to provide magnesium oxide for an annealing separator which is useful for obtaining grain-oriented electromagnetic steel sheets with excellent magnetic properties and insulating properties. To resolve the above object, an aspect of the present invention resides in magnesium oxide for an annealing separator which has an adhesion water content and a hydration water content each falling in the quadrilateral region defined by the following points a to d as the vertices in a graph representing the adhesion water content-hydration water content relationship: a: adhesion water content: 0.25 mass %, hydration water content: 0.1 mass % b: adhesion water content: 0.60 mass %, hydration water content: 0.1 mass % c: adhesion water content: 0.40 mass %, hydration water content: 6.0 mass % d: adhesion water content: 0.20 mass %, hydration water content: 6.0 mass %.

Divalent ions are extracted from solids by leaching to form a divalent ion-containing solution. The divalent ion-containing solution is subjected to concentration to form a concentrated divalent ion-containing solution. Precipitation of a divalent ion hydroxide salt is induced from the concentrated divalent ion-containing solution. In other cases, the concentrated divalent ion-containing solution is exposed to carbon dioxide to induce precipitation of a divalent ion carbonate salt.

Divalent ions are extracted from solids by leaching to form a divalent ion-containing solution. The divalent ion-containing solution is subjected to concentration to form a concentrated divalent ion-containing solution. Precipitation of a divalent ion hydroxide salt is induced from the concentrated divalent ion-containing solution. In other cases, the concentrated divalent ion-containing solution is exposed to carbon dioxide to induce precipitation of a divalent ion carbonate salt.

The invention relates to chemical technologies, specifically nanoparticles of flame retardant magnesium hydroxide, and a process for the preparation thereof. The present nanoparticles of flame retardant magnesium hydroxide, including surface-processed nanoparticles, have a hexagonal plate-like structure with a specific surface area of up to 20 m.sup.2/g, an average diameter of the secondary particles of up to 2 m, a diameter of 10% of the secondary particles of up to 0.8 m, a diameter of 90% of the secondary particles of up to 5 m, with a longitudinal size of the primary particles of from 150 to 900 nm, and a thickness of from 15 to 150 nm.

The invention relates to chemical technologies, specifically nanoparticles of flame retardant magnesium hydroxide, and a process for the preparation thereof. The present nanoparticles of flame retardant magnesium hydroxide, including surface-processed nanoparticles, have a hexagonal plate-like structure with a specific surface area of up to 20 m.sup.2/g, an average diameter of the secondary particles of up to 2 m, a diameter of 10% of the secondary particles of up to 0.8 m, a diameter of 90% of the secondary particles of up to 5 m, with a longitudinal size of the primary particles of from 150 to 900 nm, and a thickness of from 15 to 150 nm.

Disclosed herein are system and methods to effectively leach coal ash with hydrochloric acid and separate an insoluble silica product and then selectively precipitate, from the leachate, a number to value-added, strategic, marketable products using a hydroxide reagent. The resulting precipitated products include iron, aluminum, magnesium, calcium, and a mixture of rare earth elements and transition metals. These can be separated as hydroxides or converted to oxides or carbonates. Using hydrochloric acid for leaching and converting the chloride to sodium chloride in the final step results in practically no waste for this process. The silica can be further purified using sodium hydroxide fusion or caustic leach methods and some minor streams from this process are recycled to minimize any waste stream. These systems and methods can be applied to a number of other industrial waste products such as red mud from the aluminum process, slag from steel furnaces, mine tailings, and other metal-bearing waste streams.

A magnesium hydroxide satisfies: (A) primary particles with an average width as measured using a SEM method of between 0.1 m and 0.7 m inclusive; (B) a degree of monodispersity of 50% or greater wherein degree of monodispersity (%)=(average width of primary particles as measured using the SEM method/average width of secondary particles as measured using a laser diffraction method)100; (C) a ratio D90/D10 of the volume-based cumulative 90% particle diameter (D90) to the volume-based cumulative 10% particle diameter (D10) as measured using a laser diffraction method of 10 or less; and (D) a lattice strain in the <101> direction as measured using an X-ray diffraction method of 310-3 or less. A nonaqueous secondary battery separator using the magnesium hydroxide and a nonaqueous secondary battery using the separator are provided. Improved heat resistance and smoking suppressibility of a nonaqueous secondary battery are disclosed.

A magnesium hydroxide satisfies: (A) primary particles with an average width as measured using a SEM method of between 0.1 m and 0.7 m inclusive; (B) a degree of monodispersity of 50% or greater wherein degree of monodispersity (%)=(average width of primary particles as measured using the SEM method/average width of secondary particles as measured using a laser diffraction method)100; (C) a ratio D90/D10 of the volume-based cumulative 90% particle diameter (D90) to the volume-based cumulative 10% particle diameter (D10) as measured using a laser diffraction method of 10 or less; and (D) a lattice strain in the <101> direction as measured using an X-ray diffraction method of 310-3 or less. A nonaqueous secondary battery separator using the magnesium hydroxide and a nonaqueous secondary battery using the separator are provided. Improved heat resistance and smoking suppressibility of a nonaqueous secondary battery are disclosed.

An object of the present invention is to provide magnesium oxide for an annealing separator which is useful for obtaining grain-oriented electromagnetic steel sheets with excellent magnetic properties and insulating properties. To resolve the above object, an aspect of the present invention resides in magnesium oxide for an annealing separator which has an adhesion water content and a hydration water content each falling in the quadrilateral region defined by the following points a to d as the vertices in a graph representing the adhesion water content-hydration water content relationship: a: adhesion water content: 0.25 mass %, hydration water content: 0.1 mass % b: adhesion water content: 0.60 mass %, hydration water content: 0.1 mass % c: adhesion water content: 0.40 mass %, hydration water content: 6.0 mass % d: adhesion water content: 0.20 mass %, hydration water content: 6.0 mass %.