The invention relates to a process for producing proppants, including the following steps: providing red mud, providing fly ash, producing a mixture from the red mud and the fly ash so that the mixture has a first moisture content in the range of 7 to 30 wt. %, producing a granular product from the mixture, and sintering the granular product.

There is provided synthetic proppants, and in particular polysilocarb derived ceramic proppants. There is further provided hydraulic fracturing treatments utilizing these proppants, and methods of enhance hydrocarbon recovery.

There is provided an apparatus and process for manufacturing a brick or paver with a high content of coal ash (ranging from 60% to 100% coal ash or fly ash) so that a waste product (coal ash, and more particularly Class F coal ash) from a coal-fired power plant is incorporated into a building product (high content fly ash brick or paver). Also provided is a variable firing tray to support the dried, high content coal ash bricks/pavers as the dried products are sent through a tunnel kiln, to improve circulation around the individual bricks/pavers and thereby result in reduced firing time in the kiln.

The disclosure discloses a method for preparing a multifunctional ecological exterior wall, including: preparing a ceramic board of a ceramic thermal insulation waterproof layer; preparing a ceramic sound-absorbing board of a sound-absorbing layer; and installing a ecological exterior wall: leveling a surface of the wall of a building with cement slurry, and applying a cement bonding layer thereon; laying the ceramic thermal insulation waterproof board on the cement bonding layer, and applying the cement bonding layer on the ceramic board; laying the ceramic sound-absorbing board on the cement bonding layer and reserving a gap used to place a pipe; driving the screw-thread steel bolt from the surface of the ceramic sound-absorbing board into the wall obliquely; installing and fixing the pipe in the gap, which is reserved at the upper of the ceramic sound-absorbing board; planting a green plant on the surface of the ceramic board of the sound-absorbing layer.

The disclosure discloses a method for preparing a multifunctional ecological exterior wall, including: preparing a ceramic board of a ceramic thermal insulation waterproof layer; preparing a ceramic sound-absorbing board of a sound-absorbing layer; and installing a ecological exterior wall: leveling a surface of the wall of a building with cement slurry, and applying a cement bonding layer thereon; laying the ceramic thermal insulation waterproof board on the cement bonding layer, and applying the cement bonding layer on the ceramic board; laying the ceramic sound-absorbing board on the cement bonding layer and reserving a gap used to place a pipe; driving the screw-thread steel bolt from the surface of the ceramic sound-absorbing board into the wall obliquely; installing and fixing the pipe in the gap, which is reserved at the upper of the ceramic sound-absorbing board; planting a green plant on the surface of the ceramic board of the sound-absorbing layer.

A non-spray-dried, dry-granulated ceramic particulate mixture including at least 40 wt % coal combustion fly ash and from 4 wt % to 9 wt % water. At least 90 wt % of the particles have a particle size of from 80 μm to 600 μm.

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 μm to less than 250 μm.

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 μm. 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 μm; (c) a cold crushing strength of at least 4.0 MPa; and (d) a thermal conductivity of less than 1.5 W/(m.Math.K).

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 μm. 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 μm; (c) a cold crushing strength of at least 4.0 MPa; and (d) a thermal conductivity of less than 1.5 W/(m.Math.K).

A particulate mixture, suitable for use in ceramic article production, wherein the mixture includes from 30 wt % to 80 wt % recycled aluminium silicate material. The particulate mixture has a particle size distribution such that: (i) the d.sub.50 particle size is from 10 μm to 30 μm; (ii) the d.sub.70 particle size is less than 40 μm; and (iii) the d.sub.98 particle size is less than 60 μm.