A solid alumina composition is prepared from an acid-treated precursor composition, the precursor composition having an alumina hydroxide (Al(OH).sub.3), aluminum oxyhydroxide (AlO(OH)), or a mixture thereof; where the solid alumina composition includes -alumina characterized by having an X-ray powder diffraction pattern with peaks at 19.60.5 2 and 66.80.5 2; and where the solid alumina composition has an acidity measured by an NH.sub.3-TPD test, characterized by: (1) an acid site density ranging from about 200 to 800 mol/g; and/or (2) an acid strength distribution of: about 20%-70% weak acid sites (such as about 30-50%, about 30-40%, or about 35-40%), about 30%-80% medium acid sites (such as about 50-70%, about 60-70%, or about 60-65%), and about 0-20% strong acid sites (such as about 0-10%, about 0-5%, or about 0-2%).

One object of the present invention is to provide an apparatus for producing inorganic spheroidized particles which can significantly reduce the amount of warming gas generated and suppress the generation of soot during combustion. The present invention provides an apparatus (10) for producing inorganic spheroidized particles, including a burner (11) for producing inorganic spheroidized particles, a vertical spheroidizing furnace (15), an ammonia supply source (12), an oxygen supply source (13), an ammonia supply line (L1) located between the ammonia supply source (12) and the burner (11) for producing inorganic spheroidized particles, and an oxygen supply line (L2) located between the oxygen supply source (13) and the burner (11) for producing inorganic spheroidized particles.

One object of the present invention is to provide an apparatus for producing inorganic spheroidized particles which can significantly reduce the amount of warming gas generated and suppress the generation of soot during combustion. The present invention provides an apparatus (10) for producing inorganic spheroidized particles, including a burner (11) for producing inorganic spheroidized particles, a vertical spheroidizing furnace (15), an ammonia supply source (12), an oxygen supply source (13), an ammonia supply line (L1) located between the ammonia supply source (12) and the burner (11) for producing inorganic spheroidized particles, and an oxygen supply line (L2) located between the oxygen supply source (13) and the burner (11) for producing inorganic spheroidized particles.

Inorganic oxide particles having a D50 of 5.5-9.0 m and a pressure loss of 1.75-2.81 kPa in air permeation at a pressure of 12 kPa.

Inorganic oxide particles having a D50 of 5.5-9.0 m and a pressure loss of 1.75-2.81 kPa in air permeation at a pressure of 12 kPa.

Provided is a method for producing a reduced form of a metal oxide, the method being capable of preventing the production of carbon dioxide. The method for producing a reduced form of a metal oxide may use a partition member and a high-melting-point material that comprises an absorbent material and an insulation material.

Provided is a method for producing a reduced form of a metal oxide, the method being capable of preventing the production of carbon dioxide. The method for producing a reduced form of a metal oxide may use a partition member and a high-melting-point material that comprises an absorbent material and an insulation material.

A powder for additive manufacturing which is an inorganic oxide powder, wherein D10 is 1.0 to 4.0 m, D50 is 5.5 to 9.0 m, D90 is 20.0 to 40.0 m, and the volume ratio of particles having a particle size of 16.8 to 60.0 m is 15.0 to 22.0 vol %.

A powder for additive manufacturing which is an inorganic oxide powder, wherein D10 is 1.0 to 4.0 m, D50 is 5.5 to 9.0 m, D90 is 20.0 to 40.0 m, and the volume ratio of particles having a particle size of 16.8 to 60.0 m is 15.0 to 22.0 vol %.

A spherical alumina powder, wherein D50 is 0.1 to 40 m; a circularity is 0.90 or more and 1.00 or less; an -phase percentage is 60% or more and 100% or less; and a particle surface roughness represented by Equation (1) below is 1.14 or more and 1.35 or less:

[00001]$\begin{array}{cc}\mathrm{Particle}\mathrm{surface}\mathrm{roughness}=\mathrm{BET}\mathrm{specific}\mathrm{surface}\mathrm{area}A/\mathrm{sphere}-\mathrm{equivalent}\mathrm{specific}\mathrm{surface}\mathrm{area}\mathrm{Sa}\mathrm{calculated}\mathrm{from}\mathrm{particle}\mathrm{size}\mathrm{distribution}.& \mathrm{Equation}\left(1\right)\end{array}$