Genesis Research Corporation

Williams Technologies, Inc.

Integrated Carbons Corporation

James K Kindig

James E Reynolds

An improved process for reducing sulfur oxide emissions from the combustion of coal is disclosed wherein a fuel mixture comprising calcium-containing sorbent and coal is fed to the burners and sulfur oxides react with calcium from the sorbent in a high temperature sulfur capture region, followed by additional sulfur capture in a lower temperature, high humidity sulfur capture region prior to separation of particulates from the flue gas. Sulfur capture using calcium-containing sorbents can be combined with aggressive coal beneficiation techniques to further enhance reduction of sulfur oxide emissions. The process of the invention provides a process for reducing sulfur oxides that efficiently uses calcium-containing sorbents to enhance sulfur capture while reducing the need for expensive equipment or process modifications.

Process for reducing sulfur emissions with calcium-containing sorbents

Fine particle coal is beneficiated in specially designed dense medium cyclones to improve particle acceleration and enhance separation efficiency. Raw coal feed is first sized to remove fine coal particles. The coarse fraction is then separated into clean coal, middlings, and refuse. Middlings are comminuted for beneficiation with the fine fraction. The fine fraction is deslimed in a countercurrent cyclone circuit and then separated as multiple fractions of different size specifications in dense medium cyclones. The dense medium contains ultra-fine magnetite particles of a narrow size distribution which aid separation and improves magnetite recovery. Magnetite is recovered from each separated fraction independently, with non-magnetic effluent water from one fraction diluting feed to a smaller-size fraction, and improving both overall coal and magnetite recovery. Magnetite recovery is in specially designed recovery units, based on particle size, with final separation in a rougher-cleaner-scavenger circuit of magnetic drum separators incorporating a high strength rare earth magnet.

Coal cleaning process

The present invention is further directed towards a method for determining the efficiency of separation of a dense media separation process. This method includes determining an apparent distance a particle must travel in a dense media cyclone to be correctly beneficiated. From this apparent distance, an apparent velocity a particle must achieve to be correctly beneficiated is calculated. This apparent velocity is used, along with cyclone geometry and operational parameters to calculate a divergence value which indicates the efficiency of separation. The present invention also includes a method for selecting cyclone geometry and operating parameters which includes determining separation efficiency and adjusting geometry and parameters in a manner to obtain improved efficiency.

Process for beneficiating particulate solids

The present invention provides a method for selecting magnetite to form a dense media for beneficiation of fine particulate solids such that the particulate solids are as buoyant with respect to the dense media as if the solids were in a true liquid having a specific gravity equal to that of the dense media. The method involves determining a magnetite particle diameter such that the diameter ratio of particulate solid to magnetite lies above a diameter ratio partition curve. The invention is also directed toward using magnetite having a particle diameter less than about 0.005 mm and a mean particle diameter of about 0.0025 mm. Such magnetite is formed from a gas phase pyrohydrolysis reaction on an aqueous iron (ferrous) chloride solution. The present invention is further directed towards a method for determining the efficiency of separation of a dense media separation process. This method includes determining an apparent distance a particle must travel in a dense media cyclone to be correctly beneficiated. From this apparent distance, an apparent velocity a particle must achieve to be correctly beneficiated is calculated. This apparent velocity is used, along with cyclone geometry and operational parameters to calculate a divergence value which indicates the efficiency of separation. The present invention also includes a method for selecting cyclone geometry and operating parameters which includes determining separation efficiency and adjusting geometry and parameters in a manner to obtain improved efficiency.

A method for determining the efficiency of separation of a dense media separation process is disclosed including determining an apparent distance a particle must travel to be correctly beneficiated and calculation of an apparent velocity for correct beneficiation. Apparent velocity, cyclone geometry, and operating parameters are used to calculate a divergence value which indicates the efficiency of separation. Cyclone geometry and operating parameters may be selected for use in a dense media separation process by adjusting geometry and operating parameters in a manner to obtain desired efficiency.

A method and composition are provided for decreasing emissions of sulfur oxides and nitrogen oxides upon combustion of carbonaceous fuel material. In particular, the composition comprises a refined coal, having low ash-forming material and inorganic sulfur content, a sulfur sorbent, a sulfation promoter, and a catalyst for the reaction of sulfur dioxide to sulfur trioxide. Reduced emissions of sulfur oxides are achieved by combusting the composition in an oxygen restricted burner to lessen the effect of sorbent sintering while obtaining other advantages associated with mixing a sulfur sorbent with the carbonaceous material prior to combustion. Nitrogen oxides emissions are reduced by use of an oxygen restricted burner which lowers the flame temperature. Nitrogen oxides emissions are also reduced by lower flame temperatures resulting from endothermic reactions which are undergone by the sulfur sorbent and promoter.

Method and composition for decreasing emissions of sulfur oxides and

A process for substantially reducing the amount of insoluble fluoride-forming species in a coal feed material comprising slurrying a coal feed with a fluoride acid in the presence of an amount of fluoride-complexing species at least equal to the amount necessary to form tightly-bound complex ions with substantially all free-fluoride-ions in the slurry to produce a leached coal product and a spent leach liquor, and separating the leached coal product from the spent leach liquor. The process produces a clean purified fuel with ash content of less than about 5%, and preferably less than about 1%. Loss of fluorine values by formation of insoluble fluorides is minimized. Alkali metals and alkaline earths are substantially dissolved. The process generally comprises sizing the coal to 10 mm or less, leaching the sized coal with hydrofluoric acid in the presence of a determinable amount of a fluoride-complexing species such as silicon or aluminum, separating the leached coal from the spent leach liquor, and optionally some or all of the following: (a) pre-drying or physically beneficiating feed with high moisture or high mineral matter (ash) content; (b) cleaning the leached coal by washing and/or (c) heat treatment; (d) freeing pyrite (and other heavy minerals) and coal from attached silicates and aluminosilicates and physically separating the freed pyrite; (e) subjecting the leached coal to a second strong acid leach. In the preferred processes, hydrofluoric acid is recovered for recycling.

Process for producing a clean hydrocarbon fuel from high calcium coal

This invention discloses processes for the treatment of coal and coal derivatives in order to remove contaminates to produce a high purity coal product. The processes generally comprise a sequential acid leaching in which a hydrofluoric acid leach is followed by a hydrochloric acid leach. The pyrite and other heavy metals from the coal are removed by physical separation, either gravity or magnetic separation. The leached coal is then treated either by a washing and drying step or by a heat treatment to remove volatile halides. The HF acid and the HCl acid leachates are recovered for regeneration of the respective leachates and are recycled for use in the leaching steps. In additional processing, the coal may be pre-treated by a mild HCl acid leach and by pre-drying or physical beneficiation of the coal feedstock.

Process for producing a clean hydrocarbon fuel

The present invention provides processes for the continuous removal of contaminants from coal to produce a clean purified fuel. The processes generally comprise producing a clean coal product having a mineral matter content of less than about 5 percent by weight from coal and coal derivatives by leaching feed coal crushed or sized to less than about 1 inch with a mixture of hydrochloric and hydrofluoric acids comprising less than about 70 weight percent HF and less than about 38 weight percent HCl at atmospheric pressure and at a temperature below the boiling point of the acid mixture. One embodiment of the present invention provides a process for producing a coal product with 5 percent ash content or less comprising comminuting raw coal or other coal-derived feed material to a size less than about 10 mm; leaching the comminuted coal with a mixture of HF and HCl comprising less than about 70 percent by weight HF and less than 38 percent by weight HCl at atmospheric pressure and a temperature below boiling, preferably ambient; separating the leached residue from the spent acid; washing the leached residue substantially free of spent acids and dissolved solids; separating pyrite from the coal by physical means; reducing halogens on the coal to an acceptable level by thermal treatment; and regenerating the mixture of HF and HCl by dual pyrohydrolysis and sulfation of the spent acids to recover substantially all of the fluorine value except for that reporting to waste as MgF.sub.2, either as HF or as volatile fluorides which are recycled. Another embodiment of the invention provides processes for producing HF, HCl, and mixtures thereof from complex aqueous streams containing at least two metal halide salts one of which will pyrohydrolyze in the presence of water vapor to form hydrogen halide and the metal oxide and one of which will not, but will in the presence of water vapor, SO.sub.2 and oxygen form hydrogen halide and metal sulfate.

Growing community of inventors

Boulder, CO, United States of America

James K Kindig