Combustible briquette

Abstract

The present invention provides a composition and method for making combustible briquettes from industrial waste, particularly from industrial fines, which are useful in the manufacture of steel. The fines are mixed with a binder comprising an aqueous solution of sodium silicate, formed into briquettes and dried prior to use.

Description

[0001] The present application claims priority from a Provisional Application filed Jan. 25, 1999, and having U.S. Ser. No. 60/117,121.

FIELD OF THE INVENTION

[0002] The present invention generally relates to combustible briquettes. More particularly, the present invention relates to briquettes comprised of industrial waste, such as fines, which are particularly useful in the manufacture of iron and steel.

SUMMARY OF THE INVENTION

[0003] The present invention is for combustible briquettes comprised of industrial waste products; such combustible briquettes preferably comprised of industrial fines preferably mixed with a sodium silicate component. One embodiment of the combustible briquette is comprised of ferro-silicon fines, where the fines are in a ratio of iron to silicon being 1:4, and such fines being mixed with an agglomerating component which is an aqueous mixture of sodium silicate.

[0004] Alternatively, other fines such as silicon alloy, coal, aluminum, ceramics, lead, copper and other industrial waste products, all of which are typically minute, of a high mesh, such that they are discarded after they are produced by traditional industrial processes, are used as components for the combustible briquette.

[0005] One embodiment of a combustible briquette made according to the present invention is comprised of the mixture of an aqueous solution of alkaline water and 10% sodium silicate which is added to ferro-silicon fines, and such mixture is cured within molds to form a hardened briquette. Alternatively, a sodium silicate/fine slurry mixture is poured into a mold and compressed therein to form a hardened briquette. The resultant combustible briquette is water indurant, hard, and durable sufficient to withstand exposure to the elements.

[0006] Due to the sodium silicate binder composition utilized, the resulting combustible briquette exhibits very low pollutant-emitting properties when it is burned, having low sulfur emissions, particulate emissions, and other noxious gas emissions.

[0007] Therefore, the primary object of the present invention is to provide a combustible briquette, which can be made from industrial waste products.

[0008] A further object of the present invention is to provide a combustible briquette which has a significantly low pollutant output when combusted.

[0009] Another object of the present invention is to provide an economical method of making a combustible briquette from industrial waste.

[0010] Other features, objects, and advantages of the present invention will become apparent after review of the hereinafter set forth Detailed Description of the Invention.

DETAILED DESCRIPTION OF THE INVENTION

[0011] The present invention is for a combustible briquette, which is comprised of industrial waste in the form of small particles of dust, powder or fines. A mixture of fines, typically produced and discarded from other industrial processes, is used in the present invention. Such particles, dust, or fines vary in size depending upon their composition, ranging from about one (1) inch fines to dust particles or powder of about 400 mesh size. As one of ordinary skill in the art will readily appreciate, larger particles greater than approximately ⅜ inch are measured in screen size, and can be characterized in inches, while smaller particles are measured in mesh size. The present inventive briquette can be comprised of minute fines even of 400 mesh or larger, where such fines have heretofore typically been considered as waste products requiring disposal. There are numerous fines that can be used as a component for the combustible briquette, to include iron (Fe), copper (Cu), aluminum (Al), lead (Pb), zinc (Zn), coal, bronze, brass, carbon (C), magnesium (Mg), silicon (Si), manganese (Mn) and can also include “filter cake,” such as is found in settling ponds of coal treatment facilities, machine turnings, and material recovered from slag processing, dust produced by blast oxygen furnaces, blast furnaces and electric arc furnaces in their exhaust systems, and “scale” produced from mechanical interaction with semi-molten metal in a variety of forms.

[0012] Once the dust or fines are accumulated, they are mixed with an aqueous form of sodium silicate to agglomerate into a combustible briquette. Sodium silicate (Na2Si409, Na2Si03) is a generic term for a family of chemicals comprised of sodium oxide Na2O, silica SiO2, and typically water H2O. Commercial grades of sodium silicate are readily available and fairly inexpensive. For purposes of the present invention, the preferred sodium silicate is either “K” or “STAR” Brand sodium silicates from the Philadelphia Quartz Company or the “PQ Corporation. Data sheets and analysis certificates for the K and STAR brands are attached hereto and incorporated herewith. It should be noted that the concentrations of the aqueous form of the brands are typically altered depending on final concentrations desired.

[0013] The above materials, or combinations thereof, are preferably mixed with a binder, with 10% sodium silicate by weight being optimum in most circumstances. Once the sodium silicate in its aqueous form is added to the industrial waste fines, the resultant mixture can either cure on its own to dry into a combustible briquette, or pressure is alternately applied to the mixture, typically within a mold, to form a briquette ideal for introduction into a furnace. If compression is used to form the combustible briquette, it is preferred that low pressure be exerted. For the purpose of this application, low pressure is considered to be in the range of about 180 psi to about 220 psi, with 200 psi being optimum.

[0014] Accordingly, a combustible briquette made according to the present invention comprises a mixture of about 90% industrial waste by weight to about 10% binder by weight. The industrial waste, present in different sizes ranging from fines of approximately one inch to dust particles about 400 mesh, comprises iron (Fe), copper (Cu), aluminum (Al), lead (Pb), zinc (Zn), coal, bronze, brass, carbon (C), magnesium (Mg), silicon (Si), manganese (Mn), “filter cake”, machine turnings, slag processing waste, furnace dust, scale and mixtures thereof.

[0015] Water is also a component of the industrial waste, with the amount of water varying depending upon the type of industrial waste used. For example, waste material containing sludge contains the greatest amount of water; fines from electric arc furnaces, blast furnaces or blast oxygen furnaces contains the least water; and other industrial waste materials contain water in an amount intermediate between sludge waste and fines from furnaces. The industrial waste is added in a variety of sizes ranging from particles of about one (1) inch to power or dust about 400 mesh or larger. The pH of the resulting mixture ranges from slightly acidic to slightly basic; that is, from a pH of about 6.0 to a pH of about 8.0; preferably from about pH 6.5 to about pH 7.5, and most preferably a pH of about 7.0.

[0016] The binder, present in the industrial waste/binder mixture at about 10% by weight, is sodium silicate. In one embodiment, the fines are mixed with a binder comprising 10% aqueous “K” brand sodium silicate solution (10% sodium silicate, 90% H2O). The industrial waste/binder mixture is mixed throughly, such that the particles are evenly dispersed before forming the mixture into briquettes.

[0017] In one embodiment, the industrial waste/binder mixture is formed into briquettes allowing the mixture to cure within molds. In an alternate embodiment, the briquettes are subject to low pressure in the range of about 180 psi to about 220 psi, with 200 psi being optimum.

[0018] Additionally, the dry combustible briquettes are alternately subjected to additional drying heat to further harden prior combustion in a furnace, if so desired. When intended to be used in a blast furnace, moisture can cause the briquettes to explode. Thus, in such application, drying to remove all moisture from the briquette would be necessary. It is accordingly recommended that the briquettes be dried in a range of 350-450° F. for at least 6 hours, although, other drying temperatures and times are alternately used dependant on the result desired.

[0019] In an alternate embodiment, the briquette may be dried by applying heat less than 750° F. (approximately the ignition temperature of carbon), preferably between about 350° F. to about 600° F., and most preferably about 500° F. As is apparent to one of ordinary skill in the art, the drying time required to completely dry the briquettes varies according to a number of factors, such as amount of air circulation, type of heat used for drying, and amount of moisture in the industrial waste/binder mixture.

[0020] Briquettes formed according to the present invention will vary in size depending upon a number of factors, such as size of the mold used for briquette formation. The preferred size is greater than 2 in ×2 in, or 2 inches long and 2 inches in diameter, although greater sizes having other dimensions are alternatively used. For example, in one embodiment the briquette is formed into a 2 inch by 3 inch cylinder, measuring 2 inches in diameter by 3 inches in height.

[0021] A combustible briquette produced in such manner results in a low pollutant emitting combustion burn, which is smokeless, emits very few particulates, as well as noxious gases such as nitrous oxide, sulfur, and carbon monoxide.

[0022] Additionally, the present inventive combustible briquettes are ideal in use in the formation of steel. For example, using silicon in the sodium silicate binder of the present invention produces a combustible briquette which is quite desirous for use in steel production, either being added in the initial furnace with the iron, or later in the blast oxygen furnace for the actual production of steel. The inventive briquettes are also likewise useful in the production of steel or steel-alloys in electric arc furnaces.

[0023] While there has been shown the preferred and altering embodiments of the present invention, it is to be understood that certain changes may be made in the forms and arrangements of the combustible briquette and method of manufacture, without departing from the spirit and scope of the invention as set forth in this disclosure.

Claims

1. A method for forming a combustible briquette comprising the steps of:

obtaining industrial waste fines;

adding the fines to a binder comprising an aqueous solution of sodium silicate;

mixing the fines and the sodium silicate mixture throughly;

forming the mixture in a mold; and

subjecting the mixture to a pressure to form a briquette.

2. The method of claim 1, wherein the pressure is from about 180 psi to about 220 psi.

3. The method of claim 1, wherein the pressure is about 200 psi.

4. The method of claim 1 wherein the mixture comprises 10% sodium silicate by weight.

5. The method of claim 1 wherein said fines are chosen from a group consisting of iron, silicon, coal, aluminum, ceramics, lead, zinc, copper, magnesium, manganese, silicon, bronze, brass, and mixtures thereof.

6. The method of claim 1 wherein said fines comprise ferro-silicon.

7. The method of claim 6 wherein the ferro-silicon fines are in a ratio of iron to silicon of 1:4.

8. The method of claim 1 wherein said fines comprise iron.

9. The method of claim 1 wherein the aqueous solution is at a pH of about 6.0 to about 8.0.

10. The method of claim 1 wherein the aqueous solution is at a pH of about 7.0.

11. The method of claim 1 having said fines ranging in size from about 1 inch to about 400 mesh.

12. The method of claim 1 wherein said briquette is dried using heat in the range of about 350° F. to about 600° F.