Energy, Mines & Resources - Canada

National Research Council of Canada

Canadian Patents & Development Ltd.

Floyd N Toll

Richard D Coleman

Bryan D Sparks

Michio Ikura

C Edward Capes

William L Thayer

Adam J Bennett

Thomas W McCracken

F Weldon Meadus

The invention disclosed relates to a method for drying low-quality solid carbonaceous fuels such as lignite and sub-bituminous coal to reduce the moisture content substantially to zero, and to minimize re-adsorption of moisture during storage and transporation. The method involves drying the solid fuel in a mildly reducing atmosphere at a temperature in the range of 150.degree.to 300.degree. C., preferably 200.degree.to 210.degree. C. The mildly reducing atmosphere may be provided by a gaseous lower-alkane e.g. propane and methane. In some cases, the coal may beneficiated by agglomeration with small amounts of oil.

Irreversible drying of carbonaceous fuels

An improved process is described for agglomerating ground coal in which a bridging oil is used as the agglomerating vehicle. This bridging oil is a mixture of a heavy gas oil obtained from coal/oil coprocessing and a heavy hydrocarbon oil, such as bitumen or heavy oil, preferably mixed in the proportion of about 23-40% heavy hydrocarbon oil and 60-77% heavy gas oil. The agglomerated product is mixed with additional heavy oil or bitumen and it becomes the feedstock to a coal/oil coprocessor, with heavy gas oil being formed as one of the product streams. At least part of this heavy gas oil product stream is recycled to the agglomeration stage as the heavy gas oil component of the bridging oil. This agglomeration procedure has the advantage of providing an agglomerate of excellent quality, while carrying out the agglomeration in a short time at ambient temperature and using less than 10% by weight of bridging oil.

Oil/coal coprocessing in which agglomerated coal forms part of feedstock

In the present invention, iron sulfate is added in the form of an aqueous wash solution to coal agglomerates after separation of ash from the agglomerated coal. As the agglomerates remain in a continuous water phase, a good dispersion of the iron sulfate solution throughout the agglomerate matrix occurs. At this stage an unexpectedly strong adsorption of Fe ions onto the coal surfaces occurs without any adverse effects on agglomerate integrity and the ability to separate it selectively by floatation. Furthermore, this good dispersion also results in over 94% of the iron sulfate in the wash solution being transferred to the agglomerates. This manner of addition of iron sulphate to coal has been shown to elevate advantageously the lowest temperature at which coke formation occurs during coprocessing.

Incorporation of a coprocessing additive into coal/oil agglomerates

Apparatus for dispersing particulate material in a liquid, for example, particulate coal and agglomerating oil in water, comprising an upwardly extending, cylindrical container for the flow of the coal, oil and water upwardly therethrough passed a lower, flat blade type turbine rotor, an intermediate knife blade type turbine rotor and an upper pitched blade type turbine rotor. An annular shaped portion is around the intermediate rotor and houses the intermediate rotor in a cylindrical duct, longitudinally extending baffles extend upwardly along the container inner surface and are spaced therefrom. The lower rotor causes radially outward flow of the coal-water-oil mixture, the intermediate rotor causes fine break down and homogenization of the coal-water-oil mixture, while the pitched blade type turbine rotor causes reverse flow of the homogenized coal-water-oil mixture producing seed agglomerates of carbonaceous coal particles and oil leaving any ash particles dispersed in the water.

Particulate material in a liquid

Growing community of inventors

Russell, Canada

Floyd N Toll