Methods and apparatus for use in processing and treating particulate material

A method for use in treating fly ash or bottom ash particulate material obtained by burning coal, the particulate material including plurospheres and the method including the steps of mixing the material with a fluid to form a slurry, and subjecting the slurry to vibrations at an ultrasonic frequency such that there is cavitation of the particulate material and the plurospheres are cracked open, thereby releasing spheres of the material which are encapsulated within the plurospheres, and leaching alkali salts coating the surfaces of the particulate material from the material in a tubular pressure reactor at elevated values of pressure and heat.

A method for use in treating fly ash or bottom ash particulate material obtained by burning coal, the particulate material including plurospheres and the method including the steps of mixing the material with a fluid to form a slurry, and subjecting the slurry to vibrations at an ultrasonic frequency such that there is cavitation of the particulate material and the plurospheres are cracked open, thereby releasing spheres of the material which are encapsulated within the plurospheres, and calcining the particulate material in the presence of a reducing agent, such as carbon monoxide gas, and converting the residual particulate material containing iron oxides in the form of magnetite (FeO.Fe2O3) and hematite (Fe2O3), not previously removed by magnetic separation, into gamma ferric oxides, (FeO), resulting in a particulate material which is substantially lighter in colour than it would otherwise be.

A method for use in treating fly ash or bottom ash particulate material obtained by burning coal, the particulate material including plurospheres and the method including the steps of mixing the material with a fluid to form a slurry, and subjecting the slurry to vibrations at an ultrasonic frequency such that there is cavitation of the particulate material and the plurospheres are cracked open, thereby releasing spheres of the material which are encapsulated within the plurospheres, and calcining the particulate material in an oxidising atmosphere, and the residual particulate material containing iron oxides in the form of magnetite (FeO.Fe2O3), not previously removed by magnetic separation, is converted into hematite, resulting in a particulate material which is substantially yellow to orange in colour.

A method for use in treating fly ash or bottom ash particulate material obtained by burning coal, the particulate material including plurospheres and the method including the steps of mixing the material with a fluid to form a slurry, and subjecting the slurry to vibrations at an ultrasonic frequency such that there is cavitation of the particulate material and the plurospheres are cracked open, thereby releasing spheres of the material which are encapsulated within the plurospheres, the particulate material having been calcined to gamma ferric oxide, and being therefore more magnetic than magnetite and hematite, and separating the gamma ferric oxide from the residual non-magnetic fraction.

A method for use in treating fly ash or bottom ash particulate material obtained by burning coal, the particulate material including plurospheres and the method including the steps of mixing the material with a fluid to form a slurry, and subjecting the slurry to vibrations at an ultrasonic frequency such that there is cavitation of the particulate material and the plurospheres are cracked open, thereby releasing spheres of the material which are encapsulated within the plurospheres, and calcining the particulate material to burn off the carbon material.

A method for use in treating fly ash or bottom ash particulate material obtained by burning coal, the particulate material including plurospheres and the method including the steps of mixing the material with a fluid to form a slurry, and subjecting the slurry to vibrations at an ultrasonic frequency such that there is cavitation of the particulate material and the plurospheres are cracked open, thereby releasing spheres of the material which are encapsulated within the plurospheres, during the step of ultrasonic irradiation adding to the particulate material a coating agent of synthetic or natural iron oxide pigments, titanium dioxide, or precipitated calcium carbonate, the ultrasonic irradiation causing the particles to become coated and to achieve a desired colour.