Abstract: A process for preparing whitened fly ash includes the steps of: (a) subjecting fly ash to a size classification step to obtain size classified fly ash having a particle size such that at least 90 wt % has a particle size of from 44 ?m to 250 ?m; (b) optionally, contacting the size classified fly ash from step (a) with water to form a slurry, wherein the slurry has a solid content of less than 40 wt %; (c) subjecting the slurry obtained in step (b) to an exhaustive magnetic separation step to form magnetically treated fly ash, wherein the exhaustive magnetic separation step includes a first magnetic extraction step and a second magnetic extraction step, wherein the second magnetic extraction step is carried out at a higher magnetic field strength than the first magnetic extraction step; and (d) subjecting the magnetically treated fly ash obtained in step (c) to milling to form whitened fly ash.

Abstract: A process for preparing whitened fly ash includes the steps of: (a) subjecting fly ash to a size classification step to obtain size classified fly ash having a particle size such that at least 90 wt % has a particle size of from 44 ?m to 250 ?m; (b) optionally, contacting the size classified fly ash from step (a) with water to form a slurry, wherein the slurry has a solid content of less than 40 wt %; (c) subjecting the slurry obtained in step (b) to an exhaustive magnetic separation step to form magnetically treated fly ash, wherein the exhaustive magnetic separation step includes a first magnetic extraction step and a second magnetic extraction step, wherein the second magnetic extraction step is carried out at a higher magnetic field strength than the first magnetic extraction step; and (d) subjecting the magnetically treated fly ash obtained in step (c) to milling to form whitened fly ash.

Abstract: A process for making a sintered article including the steps of: (a) preparing a particulate mixture; (b) contacting the particulate mixture to water to form a humidified mixture; (c) pressing the humidified mixture to form a green article; (d) optionally, subjecting the green article to an initial drying step; (e) subjecting the green article to a firing step in a kiln to form a hot fused article; and (f) cooling the hot fused article to form a sintered article. The particulate mixture includes: (i) at least 20 wt % coarse coal combustion fly ash; and (ii) at least 30 wt % clay, wherein the coarse coal combustion fly ash has a particle size in the range of from greater than 150 ?m to less than 250 ?m.

Abstract: A porous refractory article including greater than 90 wt % coal combustion fly ash. The coal combustion fly ash is in the form of an interconnected particulate lattice structure, and wherein greater than 50% by volume of the coal combustion fly ash particles within the particulate lattice structure have a particle size of greater than 150 ?m. The article has: (a) an apparent porosity of from 30% to 50%, (b) a porosity such that the maximum pore size is less than 500 ?m; (c) a cold crushing strength of at least 4.0 MPa; and (d) a thermal conductivity of less than 1.5 W/(m·K).