Title of Invention	IMPROVED CERAMIC PROPPANT, SYSTEM FOR PRODUCTION AND PROCESS THEREOF
Abstract	The present invention relates to the ceramic proppants. In particular the invention relates to an energy efficient system and process of manufacturing the same using Raw/ naturally occurring / as mined / uncalcined Bauxite as a raw material.

Full Text

FORM - 2 THE PATENTS ACT, 1970 (39 OF 1970) PROVISIONAL SPECIFICATION (See Section 10) TITLE OF INVENTION "Improved Ceramic Proppant. System for Production and Process thereof" (a) Ajay Kumar Dasgupta (b) residing at L 4 SHIVNAGRI, KOTHRUD, PUNE 411038 State of Maharashtra, India The following specification particularly describes the nature of the invention and the manner in which it is to be performed. Field of Invention The present invention relates to the ceramic proppants. In particular the invention relates to an energy efficient system and process of manufacturing the same using Raw/ naturally occurring / as mined / uncalcined Bauxite as a raw material. Background of Invention Hydraulic fracturing is used to increase the productivity of gas wells in low permeability reservoirs by creating deeply penetrating fractures in the producing formation surrounding the well. The fracture is created by pumping a viscous fluid through perforations in the well casing or in the uncased section of the well. In this process a fluid with sand in suspension is pumped under high pressure into the producing zone of an oil or natural gas well in order to stimulate and enhance recovery. This suspension serves to enlarge existing openings and create new voids through which the oil or gas can move freely towards the producing well. When the fluid is withdrawn the silica sand remains to hold the fractures open, thereby acting as a Proppant. The major requirement of Proppant is that it should be well rounded with a high degree of sphericity, to allow ease of placement in the formation and provide maximum permeability. The proppant should also be uniform in size, having a high compressive strength, be dry, non-agglomerated, unfractured, clean and free of contaminant minerals such as feldspar, clay and calcite. In order to ensure these properties, specification usually demand a hydrochloric acid solubility of less than 3% and a withstanding elevated temperature in the well. Thus most desirable properties for propping agents in the hydraulic fracturing of subterranean formations at considerable depth are: high permeability at high formation pressures, high compressive strength, high acid resistance, low specific gravity. The two most desirable properties of a proppant are very high strength and low specific gravity. In view of this constitutes of the proppant such as Bauxite and clay are of paramount importance. Bauxite is the most important aluminium ore. It consists largely of the minerals gibbsite AI(OH)3, boehmite Y-AIO(OH), and diaspore a-AIO(OH), together with the iron oxides goethite and hematite, the clay mineral kaolinite and small amounts of anatase TiO2. It is to be noted that the cost of production of the ceramic proppant depends on selection of the raw material and the process for preparation of the same, in particular the process of calcination. It is always desirable to select locally available raw material. Further as the processes involved in the production of proppant are energy intensive, it is desirable to judiciously use the energy and achieve energy efficiency so as to reduce cost of production. Various attempts are reported in literature regarding proppants and method of manufacturing the same. It is as follows: United States Patent 4713203 discloses a superior proppant having very high permeability at formation pressures up to 20,000 psi, very high compressive strength, low specific gravity, and good acid resistance, is produced by a process comprising: (a) separating a fine fraction from a naturally occurring bauxite containing same; (b) pelletizing the separated fine fraction in the presence of water; (c) treating the pellets produced in step (b) to remove water therefrom; and (d) sintering the product of step (c) to produce a low density material suitable for use as a proppant. United States Patent 4068718 discloses an improved method of fracturing a subterranean formation wherein particles composed of sintered bauxite are placed in the formation fracture to maintain the walls of the fracture spaced apart. The sintered bauxite particles have a specific gravity greater than 3.4 and are prepared from bauxite material having a grain size of about 12 microns or less. United States Patent 4440866 discloses A process for producing high strength sintered bauxite spheres usable as fracture propping agents in oil or gas wells are produced by continuous spray-granulation of an aqueous binder-containing aluminous ore suspension to form granules which are subsequently sintered. Suitable starting materials include ores of high aluminum silicate content. United States Patent 4522731 discloses a high strength propping agent for use in hydraulic fracturing of subterranean formations comprising solid, spherical particles having an alumina content of between 40 and 60%, a density of less than 3.0 gm/cc and an ambient temperature permeability of 100,000 or more millidarcies at 10,000 psi. United States Patent 4427068 discloses sintered, spherical composite pellets or particles comprising one or more clays as a major component and bauxite, alumina, or mixtures thereof, are described, along with the process for their manufacture. The pellets may have an alumina-silica (Ab O3 -SiO2) ratio from about 9:1 to about 1:1 by weight. The use of such pellets in hydraulic fracturing of subterranean formations is also described. United States Patent 4921820 a lightweight oil and gas well proppant made by simultaneously mixing and compacting a mixture of kaolin clay which has been calcined at a temperature low enough to prevent the formation of mullite and crystobalites to an LOI of 12 or less when tested at 1400° C, and amorphous to microcrystalline silica both of which have been milled to an average agglomerated particle size of 7 microns or less to form green pellets, and then drying, screening, and sintering the pellets to form proppant pellets having a specific gravity of 2.7 or less, the proppant having a conductivity of at least 3,000 millidarci-feet as measured by the Stim-Lab Technique after 50 hours at 8,000 psi and 275° F. in the presence of deoxygenated aqueous 2% solution of KCI using sandstone shims. United States Patent 5188175 discloses a lightweight propping agent made from kaolin clay or mixtures of kaolin clay and lightweight aggregate and having an alumina content between 25% and 40%, a specific gravity of from 2.20 to 2.60 and better conductivity than sand at pressures up to 8,000 psi. United States Patent 5120455 discloses a high strength propping agent for use in hydraulic fracturing of subterranean formations comprising solid, spherical particles having an alumina content of between 40 and 60%, a density of less than 3.0 gm/cc and an ambient temperature permeability of 100,000 or more millidarcies at 10,000 psi. United States Patent 4921821 discloses a lightweight oil and gas well proppant made by simultaneously mixing and compacting a milled calcined kaolin clay powder to form green pellets and then drying, screening and sintering the pellets to form proppant pellets having a specific gravity of 3.0 or less and a conductivity of at least 4,200 millidarci-feet and preferably at least 5,100 md-ft as measured by the Stim-Lab method after 50 hours at 8,000 psi and 275° F. in the presence of deoxygenated aqueous 2% solution of KCI. United States Patent 4443347 discloses a method provided for propping a fracture in a subterranean formation which comprises injecting into a subterranean well a suspension in a carrier fluid of a pre-cured proppant charge, the pre-cured proppant charge being pre-cured prior to injection into the well, and comprising prior to injection into the well, resin coated sand particles most of which are composed of a single substrate particle with a thermoset resite coating thereon, the resite coating being one which, when it is the resin coating on sand particles of a proppant charge, produces a charge wherein at least one of: (a) the Conductivity Ratio thereof, throughout a given closure stress range, is greater than that of a charge of the uncoated sand particles having substantially the same particle size distribution; or (b) the Permeability Ratio thereof, throughout the stress range of about 2,000 to about 10,000 p.s.i., is at least about 30 perecnt that of a sintered bauxite charge of substantially the same particle size, the resin for the coating being at least one of: (1) a resole; or (2) a novolac. United States Patent 4547468 discloses an invention in respect of hollow, fine-grained ceramic proppants are less expensive and improve fracture control when compared to conventional proppants (dense alumina, mullite, bauxite, zirconia, etc.). Hollow proppants of the present invention have been fabricated by spray drying, followed by sintering in order to obtain a dense case and a hollow core. These proppants generally have high sphericity and roundness (Krumbein sphericity and roundness greater than 0.8), have diameters on average between 2250 and 125 urn, depending on proppant size required, and have strength equal to or greater than that of sand. The hollow core, the size of which can be controlled, permits better fracture control in hydraulic fracturing treatments since the proppant can be transported in lower viscosity fluids. Hollow proppants produced at the same cost/weight as conventional proppants also provide for lower costs, since less weight is required to fill the same volume. The fine-grained (preferably less than 5 urn in diameter) ceramic case provides the strength necessary to withstand closure stresses and prevent crushing. United States Patent 4623630 discloses a composite, sintered, spherical pellet and a method for its manufacture are described. The pellet comprises clay and a member of the group of bauxite, alumina, or mixtures thereof; the pellet being prepared from at least one uncalcined or partially calcined ingredient. The pellet may have an alumina-to-silica ratio from about 9:1 to about 1:1. The pellet has a specific gravity of less than 3.40. Use of such pellets in propping hydraulically fractured subterranean formations is also described. United States Patent 4658899 discloses a composite, sintered, spherical pellet and a method for its manufacture are described. The pellet is prepared from at least one uncalcined or partially calcined ingredient selected from the group consisting of clay and bauxite materials, dust collector fines and alumina. The pellet may have an alumina-to-silica ratio from about 9:1 to about 1:1. The pellet has a specific gravity of less than 3.40. Use of such pellets in propping hydraulically fractured subterranean formations is also described. United States Patent 4639427 discloses aluminous proppant media in the form of sintered bauxite spheres containing silica are improved in resistance to stress corrosion by inclusion of zirconia in the mix prior to firing in the amount of a silica to zirconia ratio of from 6/1 to 20/1. United States Patent 4879181 discloses sintered, spherical composite pellets or particles comprising one or more clays as a major component and bauxite, alumina, or mixtures thereof, are described, along with the process for their manufacture. The pellets may have an alumina-silica (Al2 O3 -SiO2) ratio from about 9:1 to about 1:1 by weight. The use of such pellets in hydraulic fracturing of subterranean formations is also described. United States Patent 4894285 discloses sintered, spherical composite pellets or particles comprising one or more clays as a major component and bauxite, alumina, or mixtures thereof, are described, along with the process for their manufacture. The pellets may have an alumina-silica (AI2 O3 -SiO2) ratio from about 9:1 to about 1:1 by weight. The use of such pellets in hydraulic fracturing of subterranean formations is also described. United States Patent 6753299 discloses an improved lightweight and highly permeable proppant composition for use in increasing the productivity of a gas or oil well. The proppant composition includes equal amounts by weight of uncalcined bauxite, uncalcined shale and quartz, held together with a binder formed of wollastonite and talc in an amount of less than 10% by weight of the composition. The proppant composition has an alumina content of less than 25% by weight of the composition and a silica content of over 45% by weight of the composition. United States Patent 20070023187 discloses sintered, spherical composite pellets having high strength and low density, are described, along with processes for their manufacture. One method includes forming a green pellet from a mixture of clay, bauxite or a clay-bauxite mixture with a sacrificial phase such that upon sintering of the pellet, the sacrificial phase is removed from the pellet. The use of such sintered pellets in hydraulic fracturing of subterranean formations is also described. European Patent EP1446552 discloses an improved lightweight and highly permeable proppant composition for use in increasing the productivity of a gas or oil well. The proppant composition includes equal amounts by weight of uncalcined bauxite, uncalcined shale and quartz, held together with a binder formed of wollastonite and talc in an amount of less than 10% by weight of the composition. The proppant composition has an alumina content of less than 25% by weight of the composition and a silica content of over 45% by weight of the composition. European Patent EP0102761 discloses a composite, sintered, spherical pellet characterised in that it comprises clay and bauxite and/or alumina, the pellet containing a major portion on a dry weight basis of clay, having an alumina to silica ratio on a dry weight basis of from 9:1 to 1:1 and having an apparent specific gravity of less than 3.40 is disclosed, The present invention provides advantages over the prior art when the pellets are used in the hydraulic fracturing of subterranean formations. European Patent EP0116369 discloses a proppant medium for fractured wells consisting of spheres having a ceramic matrix, said matrix including 15 to 40% of micropores, said spheres having an individual particle bulk density of 2 to 3 grams per cubic centimeter, and said proppant medium having a permeability at 10,000 psi at least 400% greater than that of silica sand proppant media of the same particle size distribution. Such proppants can be produced by forming into pellets a mixture comprising bauxite, with or without a sintering aid, and, if desired, a high aluminous alumino-silicate clay, and firing said pellets, wherein there is included in said mixture a finely divided material which combusts or volatilizes during said firing so as to produce proppant particles having 15 to 40% by volume of micropores. European Patent EP0207427 discloses aluminous proppant media in the form of sintered bauxite spheres containing silica are improved in resistance to stress corrosion by inclusion of zirconia in the mix prior to firing in the amount of silica to zirconia ratio of from 6/1 to 20/1. WO/2003/042497 discloses invention relating to oil and gas well proppant particulate material comprising a mixture of: a) from about 1 % by weight to about 10 % by weight talc, b) from about 1 % by weight to about 10 % by weight wollastonite, c) from about 5 % by weight to about 33 % by weight bauxite, d) from about 10 % by weight to about 65 % by weight quartz, e) from about 10 % by weight to about 65 % by weight shale, wherein the mixture has an alumina content of less than about 25 % by weight, and a silica content of greater than about 45 % by weight. A preparation method is also disclosed to obtain said composite, sintered spherical pellets of proppant, based on the addition of water and starch to the powder mixture of the raw materials, followed by a forming step, to obtain spherical particles, and a sintered step Thus the study of the related prior art reveals several technological gaps such as: ü In most of the prior art reported the raw material is the calcined bauxite and not the naturally occurring bauxite, this adds to the cost of production ü Lack of use of locally available raw bauxite as available in the mines rather than calcined Bauxite as starting material ü Utilization of the hot gases in the process of sintering and calcinations for drying purpose Necessity has constantly been felt to produce the ceramic proppant using an energy efficient process utilizing the available abandoned quantity of raw bauxite in particular in India terrain by providing process that overcomes the problems related to the fine dispersion of iron oxides, kaolinitic clay, calcium and titanium mineral in the crystal lattice which makes the impurity liberation a very difficult process; blend the bauxite from various mines suitably to get the exact raw mix for ceramic proppant obviating the use of calcined bauxite as a raw material. SUMMARY OF THE INVENTION The main object of the invention is to provide ceramic proppant from locally available uncalcinated / naturally available / as mined / raw bauxite from mine and an energy efficient process and system of manufacture thereof. Yet another object of the invention is to provide a ceramic proppant. Yet another object of the invention is to produce ceramic proppant from the high and medium grade wherein the range of Alumina is in the range of 55 to 86% by weight , bauxite having fine dispersion of iron oxides, kaolinitic clay, calcium and titanium mineral in the crystal lattice available in the Indian terrain. Yet another object of the invention is to provide energy efficient calcinations and sintering process to manufacture / produce bauxite. Yet another object of the invention is to prepare raw material for the proppant by judiciously blending plurality of different grade naturally available bauxite. Yet another object of the invention is to prepare raw material for the ceramic proppant using a combination of low and medium grade naturally available bauxite from different locations in Indian terrain. Thus in accordance with the invention the system comprises of: ü Pre-calcinationator comprising a rotary kiln with a cooler ü vibratory mill for micronisationj ü high intensive mixer for pelletising_or agglomerating; ü noduliser to polish the surface of the green_pellets; ü double drum dryer; ü rotary sintering kiln comprising provision of changing the kiln slope during operation from 1.5% to 3.5% in addition to the available variable speed of kiln rotation;adapted to fit dam ring / retainer ring in the form of adjustable protrusion having height and curvature, substantially perpendicular to the inner surface of the said kiln is adapted to fit the said kiln at internally along the circumference wherein the height of the said protrusion of the said ring results in temporarily stopping the material to increase residence time in a particular temperature zone of the kiln:-lifter in the form of projections provided along the axis of the said kiln at particular temperature zone for soaking as well as for dispersing the partially sintered material for proper heat transfer. DESCRIPTION OF THE INVENTION Features and advantages of this invention will become apparent in the following detailed description and the preferred embodiments with reference to the accompanying drawings. Figure 1 Schematic of the process (Sheet 1) Figure 2 Process stages (Sheet 2) Figure 3 Stage 1 system configuration (Sheet 3) Figure 4 Stage II system configuration (Sheet 4) The system configuration is depicted in the Figure 1. The system comprises of a vibratory mill for the micronisation of the raw material wherein the raw / naturally occurring bauxite of various grade is collected from various geographical locations and blending is carried out to get the desired composition followed by pre-calcination of the said blend in the pre-calcinator 1; vibratory mill 2 for carrying out the micronisation process to produce micro fined particles; high intensive mixer 3 for pelletising process; nodulesr 4 to polish the pellet surface and improve the sphericity; double drum dryer 5 for drying the pellets; rotary sintering kiln 6 provided with kiln slope during operation from 1.5% to 3.5% in addition to the available variable speed of kiln rotation and adapted to fit dam ring and lifter at particular temperature zone for soaking as well as for dispersing the partially sintered material for proper heat transfer; means 7 for recirculating exhaust gas from the said sintering kiln 5 to the said double drum dryer 5. Following is the process of preparing raw material for the ceramic proppant: ü Collection of the raw bauxite as mined from various sources / mines ü Blending the various lots / stocks of bauxite to get the desired composition ü Pre-calcination at the temperature of around 1100 to 1200°C depending on the quality of bauxite of the said mixture / blend to prepare calcined-bauxite as a raw material for the production of proppant Following is the process for the preparation of the ceramic proppant from the said calcined bauxite: ü micronization of the said raw material in a vibratory mill to reduce the material seize to less than 10 m size preferably in the range of 5 to 10 m to produce microfined particles; ü pelletising the said microfined particles in high intensive mixer of R11_from Eirich Germany but not limited to it; Ö feed the said pelletized material on line with the Eirich make Noduliser to polish the surface and to improve the sphericity preferably greater that 0.9 by polishing to produce green pellets; Ö optionally coating the said pellets for better acid resistance.and other advantages such as increasing conductivity; Ö drying the said green pellets without damaging sphericity of the green pellets in a double drum dryer wherein the kiln exhaust gas at the temperature of 600 - 700°C which is otherwise a waste energy through stack is utilized wherein two drum design facilitates increase in the residence time of the material in the dryer; Ö sintering and cooling in the kiln wherein rotary sintering kiln mechanical system is provided with the adjustment of the kiln slope during operation from 1.5% to 3.5% in addition to the available variable speed of kiln rotation; Ö controlling the residence time of the material in the kiln using the adjustable dam ring and lifter in the particular temperature zone for soaking as well as for dispersing the partially sintered material for proper heat transfer Ö firing the said kiln using fresh air from the cooler discharge end as secondary air for kiln firing which in turn gets heated while passing through the cooler and cooling the hot product, resulting in increasing of cooling air temperature 800°C to 900°C and the air helps for better heat value and reduces the cooling zone of the kiln. Ö harnessing the rotary sintered plant exhaust gas having temperature of around 700°C to 800°C for drying purpose in the said green pellet dryer unit. Stages of the process viz. stage I and stage II is depicted in the Figure 2. As shown the stage I essentially comprises of pre-calcination wherein the process comprises of bauxite storage from various sources/ mines (1), drying of the bauxite (2), raw bauxite crushing (3) and calcining of the said bauxite (4). Further, Stage II comprises of the steps such as the raw material grinding for micronisation of the raw material(1), agglomeration that is pelletising the said micronized material and feeding the green pellets to noduliser online to polish the surface and improve sphericity(2), drying the green pellets (3), screening to size the same (4), sintering the sized pellets in a kiln (5), passing the same to cooler (6) followed by final screening (7) product storage (8) and packaging (9). Figure 3 depicts system configuration of the said stage I that is pre-calcination. As shown in the figure the raw material is stored and dried (1 &2) initially and is fed to the crusher (3). Further the crushed material is calcined (4) in a rotary kiln that comprises of cooler, kiln drum wherein hot air is supplied by the hot air generator and induced draft is created by the I.D. (Induced draft) fan as shown in the figure. Figure 4 depicts system configuration of the said stage II. The pre-calcined material is fed to the mill for micronisation(l) followed by agglomerator / pelletisor (2) wherein pelletized material is supplied to the online Noduliser (not shown) to polish the surface and to improve the sphericity preferably greater that 0.9 by polishing to produce green pellets. Further the green polished pellets are fed to the drum double dryer (3) wherein the kiln exhaust gas at the temperature of 600 - 700°C which is otherwise a waste energy through stack is utilized. Further, the pellets are screened for sizing (4). The screened pellets are further fed for sintering process in a rotary kiln (5) comprising cooler, hot air generator, kiln drum, induced draft fan, provision of changing the kiln slope during operation from 1.5% to 3.5% in addition to the available variable speed of kiln rotation;adapted to fit dam ring / retainer ring in the form of protrusion having height and curvature, substantially perpendicular to the inner surface of the said kiln is adapted to fit the said kiln at internally along the circumference wherein the height of the said protrusion of the said ring results in temporarily stopping the material to increase residence time in a particular temperature zone of the kiln; lifter in the form of projections provided along the axis of the said kiln at particular temperature zone for soaking as well as for dispersing the partially sintered material for proper heat transfer. It is to be noted that to achieve energy efficiency, the air provided to the said cooler which in turn gets heated while passing through the cooler is provided as secondary air for kiln firing, thereby providing pre-heated air rather ambient temperature air resulting in better energy efficiency. Thus it is evident from the present invention that the stages or pre-calcination and the judiciouscombination of various system components such as noduliser, rounting of the kiln exhaust to double drum dryer, novel use of cooler air in the kiln and the use of adjustable rings and lifters in the rotary kiln results in a system and energy efficient process to produce the ceramic proppant utilizing the available abandoned quantity of locally available raw bauxite in particular in India terrain by providing process that overcomes the problems related to the fine dispersion of iron oxides, kaolinitic clay, calcium and titanium mineral in the crystal lattice which makes the impurity liberation a very difficult process; blend the bauxite from various mines suitably to get the exact raw mix for ceramic proppant obviating the use of calcined bauxite as a raw material.

Documents:

349-MUM-2008-CANCELLED PAGES(5-3-2012).pdf

349-mum-2008-claims(4-7-2008).pdf

349-MUM-2008-CLAIMS(AMENDED)-(5-3-2012).pdf

349-MUM-2008-CLAIMS(AMENDED)-(9-3-2011).pdf

349-MUM-2008-CLAIMS(GRANTED)-(27-3-2012).pdf

349-MUM-2008-CLAIMS(MARKED COPY)-(5-3-2012).pdf

349-MUM-2008-CORRESPONDENCE(IPO)-(27-3-2012).pdf

349-mum-2008-correspondence-received.pdf

349-mum-2008-description (provisional).pdf

349-mum-2008-description(complete)-(4-7-2008).pdf

349-MUM-2008-DESCRIPTION(GRANTED)-(27-3-2012).pdf

349-mum-2008-drawing(4-7-2008).pdf

349-MUM-2008-DRAWING(GRANTED)-(27-3-2012).pdf

349-mum-2008-drawings.pdf

349-MUM-2008-FORM 1(19-2-2008).pdf

349-mum-2008-form 1(4-7-2008).pdf

349-MUM-2008-FORM 1(9-3-2011).pdf

349-MUM-2008-FORM 13(COPY)-(9-3-2011).pdf

349-mum-2008-form 18(4-7-2008).pdf

349-mum-2008-form 2(4-7-2008).pdf

349-MUM-2008-FORM 2(GRANTED)-(27-3-2012).pdf

349-mum-2008-form 2(title page)-(4-7-2008).pdf

349-MUM-2008-FORM 2(TITLE PAGE)-(GRANTED)-(27-3-2012).pdf

349-MUM-2008-FORM 2(TITLE PAGE)-(PROVISIONAL)-(19-2-2008).pdf

349-mum-2008-form 3(4-7-2008).pdf

349-mum-2008-form 5(4-7-2008).pdf

349-mum-2008-form-1.pdf

349-mum-2008-form-2.doc

349-mum-2008-form-2.pdf

349-mum-2008-form-26.pdf

349-mum-2008-form-3.pdf

349-MUM-2008-MARKED COPY(5-3-2012).pdf

349-MUM-2008-REPLY TO EXAMINATION REPORT(5-3-2012).pdf

349-MUM-2008-REPLY TO EXAMINATION REPORT(9-3-2011).pdf

349-MUM-2008-SPECIFICATION(AMENDED)-(5-3-2012).pdf