Method for reforming coal ash, and method for producing fly ash for concrete admixture

Patent metadata

Field	Value
Publication number	US-11338328-B2
Application number	US-201816484327-A
Country	US
Kind code	B2
Filing date	Feb 8, 2018
Priority date	Feb 10, 2017
Publication date	May 24, 2022
Grant date	May 24, 2022

Abstract

The present invention provides a method for reforming coal ash, including classifying coal ash having 10% by mass or more of a residue on a 45 μm sieve by using a forced vortex centrifugal type classifying apparatus, under a condition that the residue on a 45 μm sieve of the coal ash after the classifying becomes in a range of 1% by mass or more and 8% by mass or less.

First claim

The invention claimed is:

1. A method for reforming coal ash, the method comprising:
classifying coal ash having 10% by mass or more of a residue on a 45 μm sieve by using a forced vortex centrifugal type classifying apparatus, under a condition that a content of the residue on the 45 μm sieve after the classifying is in a range of 1% by mass or more and 8% by mass or less.

2. The method according to claim 1 , wherein before the classifying, the residue in the coal ash on a 45 μm sieve is 40% by mass or less, a compression degree is 40% or less, a L value of lightness index in a Hunter Lab color system is 54.0 or more, and an ignition loss is 5.0% by mass or less.

3. The method according to claim 1 , wherein the classifying is carried out under a condition that an index of classification accuracy as calculated by κ=d25/d75 is 0.6 or more and 0.7 or less.

4. The method according to claim 1 ,
wherein the coal ash after the classifying has an ignition loss reduced by 8.0% or more, as compared to an ignition loss of the coal ash before the classification.

5. A method for producing fly ash for a concrete admixture, the method comprising:
classifying coal ash, in which a residue on a 45 μm sieve is in a range of 10% by mass or more and 40% by mass or less, a compression degree is 40% or less, a L value of lightness index in a Hunter Lab color system is 54.0 or more, and an ignition loss is 5.0% by mass or less, by using a forced vortex centrifugal type classifying apparatus, under a condition that a content of the residue on the 45 μm sieve after the classifying is in a range of 1% by mass or more and 8% by mass or less.

Assignees

• Mitsubishi Materials Corp

Inventors

• DOI Koota
• Yamashita Makio

Classifications

• B07B7/083 Primary

  generated by rotating vanes, discs, drums, or brushes · CPC title

• C04B28/02

  containing hydraulic cements other than calcium sulfates · CPC title

• C04B18/08

  Flue dust {, i.e. fly ash} · CPC title

• C04B2111/1087

  Carbon free or very low carbon content fly ashes; Fly ashes treated to reduce their carbon content or the effect thereof · CPC title

• C04B18/10

  Burned {or pyrolised} refuse · CPC title