A magnesium oxide powder includes a magnesium oxide particle, wherein the number of an open pore communicating with a surface of the magnesium oxide particle measured by a specific measurement method is 8.010.sup.4/m.sup.2 or less.

A magnesium oxide powder includes a magnesium oxide particle, wherein the number of an open pore communicating with a surface of the magnesium oxide particle measured by a specific measurement method is 8.010.sup.4/m.sup.2 or less.

Provided is a magnesium oxide-containing spinel powder capable of producing a ceramic sintered body having high strength and excellent strength stability. In the magnesium oxide-containing spinel powder, a 50% particle diameter (D50) is 0.30 to 10.00 m, a ratio (D90-D50)/(D50-D10) of a difference between a 90% particle diameter (D90) and the 50% particle diameter (D50) and a difference between the 50% particle diameter (D50) and a 10% particle diameter (D10) is 1.0 to 5.0, and a composition ratio of Mg and Al in terms of an oxide equivalent content is 50 to 90% by weight of MgO and 10 to 50% by weight of Al.sub.2O.sub.3.

Provided is a magnesium oxide-containing spinel powder capable of producing a ceramic sintered body having high strength and excellent strength stability. In the magnesium oxide-containing spinel powder, a 50% particle diameter (D50) is 0.30 to 10.00 m, a ratio (D90-D50)/(D50-D10) of a difference between a 90% particle diameter (D90) and the 50% particle diameter (D50) and a difference between the 50% particle diameter (D50) and a 10% particle diameter (D10) is 1.0 to 5.0, and a composition ratio of Mg and Al in terms of an oxide equivalent content is 50 to 90% by weight of MgO and 10 to 50% by weight of Al.sub.2O.sub.3.

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.

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 %.

Nanowires useful as heterogeneous catalysts are provided. The nanowire catalysts are prepared by polymer templated methods and are useful in a variety of catalytic reactions, for example, the oxidative coupling of methane to ethane and/or ethylene. Related methods for use and manufacture of the same are also disclosed.

Nanowires useful as heterogeneous catalysts are provided. The nanowire catalysts are prepared by polymer templated methods and are useful in a variety of catalytic reactions, for example, the oxidative coupling of methane to ethane and/or ethylene. Related methods for use and manufacture of the same are also disclosed.

The objective of the present invention is to provide: a spherical magnesium oxide which has high sphericity and excellent moisture resistance, and has excellent fluidity by which a resin composition exhibits excellent fluidity when filled in a resin; and a method for producing the same. The present invention is a spherical magnesium oxide characterized in that: 10-2000 ppm of boron is contained; the total content of silicon and phosphorus is 300-4000 ppm; and the sphericity that can be read from the SEM photograph is 1.00-1.10, when the volume-based cumulative 50% particle diameter (D50) measured by means of a laser diffraction scattering particle size distribution measurement, is in the range of 3-200 m.