Background of the Related Art The growth of industrial facilities around the world has generated significant public interest in the environmental impacts caused by such facilities. Industrial facilities often require significant amounts of fuel to operate and therefore diminish the world's supply of natural resources such as coal, petroleum, and natural gas. Further, many industrial facilities generate significant quantities of wastes, which must be treated or disposed of in landfills. Finally, industrial facilities can cause significant emissions of greenhouse gases and other air pollutants such as nitrogen oxides, sulfur dioxide, and particulate matter, all of which affect the quality of life in and around such facilities.

As natural resource costs continue to rise, landfill space dwindles, and regulations relating to waste treatment and emission control become more stringent, industry and the public have sought alternative fuels which reduce natural resource usage, recycle wastes, and reduce emissions of air pollutants.

Several developments have attempted to address these problems, including prior attempts to pelletize fuel to allow uniform handling and burning. Examples of such attempts are described in U. S. Patent No. 2,017,402, to Komarek et al., and U. S. Patent No. 1,503,304, to Damon, both of which are incorporated by reference herein. However, such attempts to pelletize fuel do not result in the environmental benefits of reduced use of natural resources, lower amounts of waste materials destined for landfills, and lower emissions of air pollutants and/or greenhouse gases.

To obtain environmental benefits, various attempts have been made to use waste materials or blended waste materials as fuel. Examples of such attempts are described in the following U. S. Patent references, all of which are hereby incorporated by reference: U. S. Patent No. 5,421,836, Ross; U. S. Patent No. 5,141,526,Chu; U. S. Patent No. 4,875,905, Somerville et al.; U. S. Patent No. 4,702,746, Finch; U. S. Patent No. 4,548,615, Lonchamp et al. ; U. S. Patent No. 4,496,365, Lindemann; U. S. Patent No. 4,405,331, Blaustein et al.; U. S. Patent No. 3,961,913, Brenneman et al.; and U. S. Patent No. 3,910,775, Jackman.

The prior art attempts to manufacture fuel from waste products have been met with limited success. Because of their physical and/or chemical composition, the prior art waste-derived fuels cannot be used in conventional coal-burning boilers unless the boilers undergo costly modifications. In many cases, the boilers must be replaced. Further, the prior art waste-derived fuels have lower heating values than coal and other natural resources. In addition, many of the prior art waste-derived fuels are physically soft and/or loose, and many such fuels are not pelletized. Accordingly, the fuels are difficult to handle, cause plugging of chutes, bins, and other equipment, and are not amenable to storage or transportation outdoors because they physically degrade upon exposure to water and the elements.

One method of attempting to solve the problems associated with waste-derived fuels is to blend waste materials with coal or other natural resources or coal source to produce a natural resource-derived alternate fuel. An example of one such attempt is described in U. S. Patent No. 5,743,924 to Dospoy et al., incorporated herein by reference. The method of producing the alternate fuel composition of Dospoy et al. is illustrated in FIG. 1. In Dospoy et al., the alternate fuel composition consists of coal fines, papermaking sludge and a shredded polymeric material. Most importantly, Dospoy et al. assert that their alternate fuel composition exhibits adequate

performance characteristics without resorting to the use of a binder or heating above ambient temperature. However, the material provided by Dospoy et al. still falls short of the characteristics and properties needed to provide a more widely useful fuel or fuel substitute. In particular, a more durable material is needed which can withstand the rigors of transportation and storage, particularly outdoor storage to which conventional coal is subjected.

To provide a certain measure of durability, grindability and/or softness, reference is made to the Hardgrove Grindability Index ("HGI") test. The HGI test is commonly used to measure the ease with which coal can be pulverized. As indicated in American Society for Testing and Materials Standard D409, Standard Test Method for Grindability of Coal by the Hardgrove-Machine Method, incorporated herein by reference, the HGI test involves the passing of a sample material through a set of sieves, a pulverizer, and a final sieve. In the HGI test, the sample is initially prepared by stage crushing the material and retrieving all crushed material that passes through a No. 30 sieve. The prepared material (that is, the material which passes through the No. 30 sieve) is then ground in a Hardgrove Grindability Machine. The ground material then passes. through a 16 millimeter sieve nested on a 75 micrometer sieve. The HGI value is then calculated using an equation in which the weight of the material that survives (that is, passes through) the final sieve is a variable. The HGI value of the sample material is directly proportional to the weight of the material that survives the final sieve. Hence, the lower the HGI value, the harder it is to pulverize the coal or other test material.

Of particular importance, in the HGI test the sample material has to be"amenable"to the HGI test. That is, it must possess enough physical integrity to withstand the initial screening and crushing residual material can even be obtained to pass through the Hardgrove Grindability Machine and the final sieves. It has been found that the alternate fuel provided in Dospoy et al. and other fuels described by others are too soft to survive the initial sample preparation and screening steps of the HGI test. Hence, no residual material is even available with which to conduct the final steps of the HGI test.

The HGI provides a measure of durability that is a key indicator in the material's ability to withstand rigorous handling requirements such as loading with a front-end loader; transportation on tri-axle vehicles to remote locations; dumping; outdoor placement and storage; loading onto conveyors with tractors, bulldozers, and the like; and conveyance via belt and/or screw conveyors to indoor bunkers (including such conveyance as would occur prior to use in steam generation equipment). Accordingly, the known alternate fuels either cannot be transported to remote locations or cannot be used in certain equipment, such as steam generating equipment, which requires fuel that meets a specific HGI value or range of values.

Another example of combining coal and waste to produce an alternate fuel is described in U. S. Patent No.

5,429,645 to Benson et al., which is incorporated herein by reference. Benson et al. describe a solid fuel consisting of a recycled residue derived from an anaerobic digestion process, such as one from municipal solid waste, raw sewage sludge, biomass feedstock, industrial waste, agricultural waste, or mixtures thereof. The solid fuel of Benson et al. may also contain a coal constituent. This fuel contains several disadvantages. First, the fuel's heating content is not comparable to the heating value of pure coal. Second, the fuel is soft, malleable, and porous, and can therefore degrade upon exposure to water and is not amenable for use in industrial facilities that require a hard fuel product, such as steam generator facilities.

Another prior art example is U. S. Patent No.

4,529,407 to Johnston et al., incorporated herein by reference.

Johnston et al. describe a fuel pellet that consists of natural cellulosic material, synthetic polymeric thermoplastic material and other naturally occurring combustible material, such as bark, stillage, distillation process by-products, or coal. This fuel also contains several disadvantages.

First, the method of producing the fuel is complex and expensive. In addition, the fuel's heating value is not comparable to that of coal. Further, the fuel pellets are not amenable to use in many conventional coal-fired boilers.

Other examples of prior art attempts to provide coal- derived or other natural resource-derived fuels include the following U. S. Patent references, all of which are incorporated herein by reference: U. S. Patent No. 5,242,470, Salter et al.; U. S. Patent No. 4,981,494, Breuil et al. ; U. S. Patent No. 4,372,749, Nielsen et al.; U. S. Patent No. 4,236,897, Johnston et al.; U. S. Patent No. 4,159,684, Kirkup; U. S. Patent No. 4,152,119, Shulz; and U. S. Patent No. 4,135,888, Waltrip.

These fuels also suffer from certain disadvantages.

They are too expensive to produce, possess high moisture contents or low heating values, cannot be used in a wide variety of existing coal-burning equipment, and are soft and/or easily fragmented.

Accordingly, we have determined that it is desirable to provide a pelletized fuel product that reduces the use of natural resources.

We have also determined that it is desirable to provide a pelletized fuel product which comprises waste materials that would otherwise be destined for landfills.

We have also determined that it is desirable to provide a pelletized fuel product that causes fewer emissions of air pollutants and or greenhouse gases than would result from an equivalent weight of conventional coal or other fuel source.

We have also determined that it is desirable to provide a pelletized fuel product that has a fresh pellet strength sufficiently high such that the fuel will not fall apart when handled, stored, and transported.

We have also determined that it is desirable to provide a pelletized fuel product that is amenable to an HGI test; that is, it would be desirable to have a pelletized fuel that possesses enough physical integrity to survive an HGI test.

We have also determined that it is desirable to provide a pelletized fuel product having a low moisture content, and thus having a heat content measured in BTU units per pound

which is comparable to the heat content of the coal source that the pelletized fuel seeks to replace and/or supplement.

We have also determined that it is desirable to provide a pelletized fuel product that burns substantially as efficiently as the coal source.

We have also determined that it is desirable to a pelletized fuel product that is amenable for storage and transportation outdoors with exposure to moisture and the elements.

We have also determined that it is desirable to have a pelletized fuel product that is amenable for use in existing coal-burning facilities without significant modification to the facilities'equipment.

Finally, we have determined that it is desirable to provide a relatively simple, cost-effective method of manufacturing the pelletized fuel product.

SUMMARY OF THE INVENTION It is therefore a feature and advantage of the present invention to benefit the environment by providing a pelletized fuel product that meets the demands of energy consumers and yet reduces the use of natural resources and contributes to the decrease in industrial waste products.

The present invention is based, in part, in our discovery of the greatly enhanced physicochemical characteristics and properties of a pelletized fuel, which is produced by mixing a pulverized coal source, a cellulosic fiber (such as papermaking sludge), granulated plastic (preferably a non-chlorinated hydrocarbon polymer, such as low density polyethylene or low density polypropylene), and a binder; forming the mixture into pellets; and heating the mixture at an elevated temperature.

Surprisingly and unexpectedly, the process of forming the mixture into pellets results in a fuel product that causes lower emissions of sulfur dioxide, nitrogen oxides, and National Greenhouse Gas Inventory emissions than pure or conventional coal source alone. In addition, the ingredient combination and the manufacturing process yields a fuel product with an appropriate hardness, pellet strength, heating value, moisture content, and

porosity such that the fuel is amenable for use in a wide variety of existing coal-burning equipment as a fuel substitute.

In accordance with the preferred embodiment of the invention, pulverized coal is combined with: (i) low-density, non-chlorinated waste plastic that has been granulated such that the major dimension of the plastic is about 3/4 inch or smaller; (ii) papermaking sludge; and (iii) starch binder. The combination consists of approximately 70-800, preferably 70-75%, coal; approximately 10-15% waste plastic; approximately 10-15% papermaking sludge; and approximately 0.5-5.0 binder, which binder is preferably about 0.5-3.0% corn starch. The mixture is formed into pellets, for example, by extruding the mixture through a die. The pellets are then dried using forced air which has been heated to a temperature of approximately between 400 and 450 degrees Fahrenheit.

There has thus been outlined, rather broadly, the more important features of the invention in order that the detailed description thereof that follows may be better understood, and in order that the present contribution to the art may be better appreciated.

In this respect, before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and to the arrangements of the components set forth in the following description or illustrated. in the drawings. The invention is capable of other embodiments and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein are for the purpose of description and should not be regarded as limiting.

As such, those skilled in the art will appreciate that the conception, upon which this disclosure is based, may readily be utilized as a basis for the designing of other compositions, methods and systems for carrying out the several purposes of the present invention. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention.

The benefits of the invention, together with other objects of the invention, along with the various features of novelty which characterize the invention, are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and the specific objects attained by its uses, reference should be had to the accompanying drawings and descriptive matter, which illustrate preferred embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS FIGs. 1 and 2 illustrate prior art methods of manufacturing fuel pellets by combining coal and waste materials.

FIG. 3 illustrates the preferred method of manufacturing the coal-based pelletized fuel product of the present invention.

FIG. 4 is a table which provides sample data of measured air emissions from samples of the present inventive fuel.

FIGs. 5-10 illustrate the grindability of example fuel pellets of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE INVENTION The pelletized fuel product of the present invention is comprised of pulverized coal or other coal fines, granulated non-chlorinated hydrocarbon polymer, cellulosic fiber, and a binder. The coal, which may consist of anthracite, bituminous, lignite, sub-bituminous, or another type of coal, makes up 70 to 80 percent, preferably 70 to 75 percent, by weight of the pelletized fuel product. The coal is preferably pulverized such that it will pass through a ten mesh screen. The cellulosic fiber, which is preferably waste papermaking sludge, but which may also consist of paper or paper fiber, wood or wood fiber, peanut or other nut shells, and the like, makes up approximately ten to fifteen percent by weight of the pelletized fuel product.

The granulated non-chlorinated hydrocarbon polymer is preferably low density waste plastic that has been ground so that it has a major dimension of not more than 3/4 inch, preferably less than 5/8 inch. The granulated polymer makes up approximately ten to

fifteen percent by weight of the pelletized fuel product.

Finally, the binder makes up 0.5 to 5.0 percent, preferably 0.5 to 3.0 percent, of the pelletized fuel and may consist of material such as starch, a starch derivative, flour, or a mixture thereof.

FIG. 3 illustrates the preferred method of manufacturing the pelletized fuel product of the present invention. A coal source is pulverized by passing the coal source through a crusher 301.

A cellulosic fiber, which is typically waste papermaking sludge, is passed through a delumper 302 to break up matted fibers and yield a relatively smooth, homogenous material.

The cellulosic fiber is preferably paper mill sludge, and more preferably paper mill sludge that is 55% to 65% moist. If drier cellulosic fiber is provided, the delumper 302 may include a water source to ensure that the cellulosic fiber is adequately wet to promote mixing.

A non-chlorinated hydrocarbon polymer, preferably low-density plastic waste, is ground in a granulator 303 to provide ground plastic with a major dimension of not more than 3/4 inch, preferably less than 5/8 inch.

The pulverized coal, delumped paper making sludge, granulated plastic, and a binder are combined in a mixer 304.

The mixed material then passes into a conditioner 305, which continues the mixing process until the mixed material is drawn through the pellet mill 306. The pellet mill 306 includes a die through which the mixed material is extruded to form pellets.

The pellets may alternatively be formed using molds or presses instead of a die. The pellets are typically M to 3/4 inch in diameter and one to three inches long, although the size may be larger or smaller depending on the size of the die or mold that is used. The extrusion process causes a chemical reaction that produces a fuel pellet that is chemically distinguishable from a simple mixture of the component ingredients. Specifically, the fuel pellets exhibit higher volatile organic compounds and lower fixed carbon values than would be obtained for a simple mixture.

The extruded pellets are passed through a dryer 307 which heats the pellets using air which has an elevated

temperature between approximately 400 and 450 degrees Fahrenheit.

(Above 450 degrees Fahrenheit, the pelletized fuel may combust.) The fuel pellets which emerge from the dryer 307 may then be transported to industrial facilities for use as a coal replacement.

The pelletized fuel manufacturing process may also include a baghouse 308 to recycle particulate matter emissions that are generated by the manufacturing process. The baghouse 308 recycles particulate matter emissions by removing dirty air from the pellet mill and dryer, cleaning particulate matter from the air, and returning the removed particulate matter to the mixer for reuse in the manufacturing process.

The pelletized fuel product of the present invention has characteristics of hardness and fresh pellet strength which provide a product that is suitable for transportation, handling, outdoor storage, and use in a wide variety of equipment. For example, the fuel pellets will survive and are amenable to an HGI test, and the HGI value and grindability of the fuel pellets are comparable to that of the ingredient coal source. Preferably, the fuel pellets are easier and/or faster to grind than the coal.

Accordingly, the fuel pellets can be used as a replacement for coal in steam generating equipment, which typically requires fuel with an HGI value of 40 to 100. In particular embodiments of the invention, the pelletized fuel exhibits a fresh pellet strength of not less than about 20 kilograms per square centimeter (more preferably, about 20 to about 25 kilograms per square centimeter), which provides a pellet that will remain intact upon ordinary handling.

Other characteristics of the preferred pelletized fuel include, but are not limited to: (1) a bulk density of about 44 to 47 pounds per cubic foot, more preferably about 46 pounds per cubic foot; (2) a porosity such that the pelletized fuel will maintain its physical integrity when exposed to or immersed in water for a moderate period of time, typically not more than one week, more typically several days; (3) a pellet that will maintain its physical integrity when immersed in water for several days, and in some embodiments for up to two weeks or more; (4) a pellet that after being exposed to or immersed in water for said period, recovers a substantial portion of its

fresh pellet strength when dry (accordingly, the pelletized fuel may be stored outside and exposed to rain without significant degradation); (5) a slagging factor of the fuel, defined as (base/acid) x percent sulfur, that is low, preferably between about 0.005 and about 0.05, more preferably about between 0.01 and 0.02, indicating a low potential for slagging problems; and (6) a fouling factor of the fuel, defined as (base/acid) x percent Na20, that is low, preferably between about 0.005 and about 0.05, more preferably between about 0.02 and about 0.03, indicating a low potential for fouling.

To satisfy the needs of energy consumers, the preferred pellet should also exhibit a moisture content of not greater than about 13 percent by weight, more preferably, no greater than about 11 percent by weight, and most preferably about 10 percent by weight or less. In most cases, the inventive pellet exhibits a heat content (e. g., British Thermal Unit value) that is at least about 80 percent of, typically and preferably 90 percent or more of, more preferably greater than, the heat content of the coal source alone.

It is important to note that the pelletized fuel of the present invention provides an ash that is chemically comparable to the ash provided by the coal source alone. Indeed the ash provided by the present pellet contains less unburned carbon than the ash obtained from the combustion of the coal source alone. This characteristic of the ash demonstrates that the pelletized fuel product burns substantially as efficiently as the coal source.

The pelletized fuel product provides several environmental benefits. First, upon combustion, the pelletized fuel product yields lower air pollutant emissions that result from the coal source. For example, sulfur dioxide emissions from the pelletized fuel product are at least about 15 percent lower than emissions of sulfur dioxide from an equivalent weight of the coal source alone. Typically, the applicants have observed that the pelletized fuel compositions of the invention can achieve about 25 percent to about 30 percent reduction in sulfur dioxide emissions relative to the equivalent amount of the conventional coal source. In fact, as illustrated by FIG. 4., laboratory test

results have demonstrated sulfur dioxide emission reductions as high as about 74 percent.

Emissions of nitrogen oxides are also at least about 15 percent lower, and typically about 25 percent to about 50 percent lower, than those emissions produced by an equipment weight of the coal source alone. In fact, FIG. 4 shows that laboratory test results in certain instances have demonstrated nitrogen oxide emission reductions as high as about 83 percent.

Further, as compared to the coal source alone, certain National Greenhouse Gas Inventory ("NGGI") emissions (e. g., carbon dioxide) are reduced, typically by about 30% or lower, by using the pelletized fuel because: (1) the fuel is comprised of up to 30% waste materials; and (2) the NGGI emissions from the waste materials have already been counted toward the NGGI. NGGI emissions include emissions of carbon dioxide, nitrous oxide, and methane. See United States Environmental Protection Agency, State Workbook: Methodologies for Estimating Greenhouse Gas Emissions (EPA-230-B-95-001), incorporated herein by reference; Walls, Greenhouse Gas Emissions from Alternative Fuels (USEPA 1991), incorporated herein by reference; Greenhouse Gas Emissions from Inventory Energy Dimensions (USEPA 1991), incorporated herein by reference.

The present invention is also directed to a method of making a pelletized fuel. This method comprises (a) mixing (i) pulverized coal source, (ii) granulated, non-chlorinated hydrocarbon polymer, (iii) cellulosic fiber, and (iv) binder to provide a mixture; (b) forming the mixture into pellets; and (c) heating the pellets at an elevated temperature to provide a pelletized fuel. Preferably, the pulverized coal source is of a fine mesh or one that is sized to pass through a number ten mesh screen. A number of coal sources can be pulverized for use in the present method, including, but not limited to, anthracite coal, bituminous coal, sub-bituminous coal, lignite, or combinations thereof.

As for the plastic or polymer component of the mixture, the plastic or polymer is granulated to a major dimension of about 3/4 inch or less, preferably 5/8 inch or less, more preferably 1/2 inch or less. Numerous polymers may be used in the method and pellet of the present invention. It is

preferred, however, that non-chlorinated polymers are used, including but not limited to, low density hydrocarbon polymers and crosslinked hydrocarbon polymers. In particular, waste low density polyethylene or low density polypropylene polymers are used.

Generally speaking, the cellulosic fiber component of the present method or pellet may comprise a variety of materials or combinations, such as paper, paper fiber, paper sludge, wood, wood fiber, nut shells, or combinations thereof.

Also, the binder component is preferably a food-based substance, more preferably comprising a starch. In particular embodiments of the invention, the binder comprises a corn starch, rice starch, potato starch, or combinations thereof.

Last but not least, the pellets formed from the mixture described herein are heated to an elevated temperature, using forced air at a temperature in the range of about 400 and about 450 degrees Fahrenheit. The temperature of the heating and the duration thereof contribute to the reduction in the moisture content of the pellet to about 13 percent or less by weight, preferably 10 percent or less. The resulting pellet is durable, maintains its physical integrity during handling, transport and storage even outdoors, in harsh weather, over a period of one week, two weeks, three weeks, one month, two months or even several months. Typically, the pelletized fuel of the present invention is amenable to an HGI test and exhibits an HGI value comparable to that of the coal source prior to pulverizing.

In a specific embodiment of the invention, the method of manufacturing the pelletized fuel includes the addition of a sorbent to the mixture prior to forming the mixture into pellets.

Suitable sorbents include, but are not limited to, dolomitic lime, magnesium lime, high-calcium lime, or another material that absorbs compounds which could otherwise be emitted as air pollutants.

The present invention is also directed to a pelletized fuel produced by a process comprising: (a) mixing a combination comprising (i) about 70 percent to about 80 percent, preferably about 70 percent to about 75 percent, by weight pulverized coal source, (ii) about 10 percent to about 15 percent by weight granulated, non-chlorinated hydrocarbon polymer, (iii)

about 10 percent to about 15 percent by weight cellulosic fiber, and (iv) about 0.5 percent to about 5 percent by weight binder to provide a mixture; (b) forming the mixture into pellets; and (c) drying the pellets at an elevated temperature. Durable, transportable, storable pelletized fuel is obtained, for example by drying the formed pellets using forced air at a temperature of about 400 to about 450 degrees Fahrenheit for a period of about 5 to about 15 minutes.

Additional Supporting Disclosure EXAMPLES The pelletized fuel composition and method of manufacture are further disclosed with reference to the following examples: EXAMPLE 1 Bituminous coal is delivered to a facility where it is dumped into a storage bin. From the storage bin, the coal is transported via a conveyor belt to a pulverizer, which crushes the coal so that the pulverized coal will pass through a ten mesh screen. Waste plastic that has been removed from milk cartons, magazine covers and wrappers, mailing packages and envelopes, and the like is also delivered to a storage bin, from which it is delivered via conveyor belt into a granulator. The granulator grinds the plastic so that the plastic granules have a major dimension not more than 1/2 inch. Paper mill sludge which is approximately 60 percent moist is delivered from a storage bin into a delumper, which breaks up matted pieces in the sludge.

The pulverized coal, granulated plastic, delumped paper sludge, and an industrial grade corn starch are delivered to a mixer (in approximate amounts of 75 percent coal, 15 percent paper, 13 percent plastic and 3 percent starch), where they are vigorously mixed to form a homogenous material. The mixture is then delivered to a conditioner, which gently stirs the mixture until the material may be drawn into a pellet mill. The pellet mill takes mixed material from the conditioner and presses the material through a die to form pellets which are approximately inch in diameter and 2 inches long. The forced extrusion causes the pellets to become warm, and the resulting heat creates a chemical reaction within each pellet so that the chemical composition of each pellet differs from a simple mixture of the

component materials. The pellets are then delivered, via a conveyor, to a dryer, which heats the pellets using forced air which has a temperature of approximately 425 degrees Fahrenheit for a 5-minute period. The resulting pellets exhibit a fresh pellet strength of 22 kilograms per square centimeter, a moisture content of 10 percent, a heat content of 10,000 BTU per pound, and an HGI value of 50.

EXAMPLE 2 Anthracite coal is delivered to a facility where it is deposited onto a conveyor belt. The conveyor belt transports the coal to a pulverizer, which crushes the coal. Waste plastic is also delivered to the facility and deposited onto a separate conveyor belt, which the plastic is transported to a granulator.

The granulator grinds the plastic so that the plastic granules have a major dimension not more than 3/8 inch. Waste paper is mixed with water until it is approximately 55 percent moist. The moist paper is delivered into a delumper, which breaks up matted pieces of paper. The pulverized coal, granulated plastic, delumped paper, and a potato starch are delivered to a mixer (in approximate amounts of 72 percent coal, 10 percent paper, 15 percent plastic and 3 percent starch), where they are vigorously mixed to form a homogenous material. The mixture is then delivered to a conditioner, which gently stirs the mixture until the material may be drawn into a pellet mill. The pellet mill takes mixed material from the conditioner and presses the material through a die to form pellets which are approximately 3/4 inch in diameter and 3 inches long. The forced extrusion causes the pellets to become warm, and the resulting heat creates a chemical reaction within each pellet so that the chemical composition of each pellet differs from a simple mixture of the component materials. The pellets are then delivered, via a conveyor, to a dryer, which heats the pellets using forced air which has a temperature of 430 degrees Fahrenheit for a 15-minute period. The resulting pellets exhibit a fresh pellet strength of 20 kilograms per square centimeter, a moisture content of 11 percent, a heat content of 10,500 BTU per pound, and an HGI value of 45.

EXAMPLE 3 Tests are performed on the pelletized fuel product of the present invention to determine its grinding characteristics as compared to those of coal. The grinding apparatus consists of two cylinders with four steel angles welded lengthwise to the interior spaced 90 degrees apart. One end of each cylinder is closed and the other has a removable steel cap. Each of the cylinders contains a number of various size nickel chrome balls to accomplish the grinding of the material. The one cylinder contains a full charge which consists of thirty-two 2-inch diameter balls, fifty-one 1-1/8-inch diameter balls and one hundred two 7/8-inch diameter balls. The other cylinder contains a short charge which consisted of fifteen 2-inch diameter balls and the same number of 1-1/8-inch diameter and 7/8-inch diameter balls as the full charge. When placed in the cylinder, both charges fill the cylinder approximately one-third full.

A representative sample of fuel pellets and a charge of balls are placed into the grinding cylinder until the cylinder is approximately one-half full. The amount of sample placed in the cylinder ranges from approximately five to seven pounds. The cylinder is sealed and rotated about its long axis at 15 revolutions per minute for 15 minutes. The sample is removed from the cylinder and a grain size analysis conducted. The sieves used for the grain size analysis may range in size from 1 M inches to No. 200. The sample, except for the material passing the No. 200 sieve is returned to the cylinder, rotated and a grain size analysis conducted. This procedure is repeated 11 times for each sample.

Samples of the two types of fuel pellets, referred as Tarentum M-inch diameter and Tarentum Coal, are run separately in the cylinder containing the full charge. Samples of the three types of pellets referred to as Tarentum M-inch diameter, Kentucky M-inch diameter, and Tarentum 3/4-inch diameter, are run separately in the cylinder containing the short charge.

Comparing the grain size analysis of each of the materials versus time run and specifically the percentage of fuel pellet material passing the No. 30,50 and 200 sieve (see FIGs.

5,6,7,8,9, and 10) reveals:

The fuel pellets achieve a higher percentage of material passing the No. 30 and 50 sieves faster than the coal; but over time the fuel pellets reach stability, whereas, the coal gradually increases and achieves a higher percentage of material passing the No. 30 and 50 sieves after 11 runs.

The Tarentum and Kentucky M-inch diameter fuel pellets achieve a higher percentage of material passing the No. 200 sieve than the coal.

Based on the testing results, the fuel pellets of the present invention initially grind faster than the coal. The amount of fuel pellets passing the No. 30 and 50 sieves stabilizes, whereas, the coal continues to increase. The percentage of material passing the No. 200 sieve increases throughout the tests for both the coal and fuel pellets.

The many features and advantages of the invention are apparent from the detailed specification, and thus, it is intended by the appended claims to cover all such features and advantages of the invention which fall within the true spirit and scope of the invention. Further, since numerous modifications and variations will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation illustrated and described, and accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of the invention.