METHOD AND APPARATUS FOR DEPITHING OF BAGASSE
FIELD OF INVENTION
The present invention relates to development of a method and apparatus for the treatment of raw material to obtain a sift able product for use in paper industry. The present invention more particularly relates to treatment of bagasse, a waste material left after the crushing of sugar cane in the sugar mills so as to obtain a sift able biomass wherein the pith, and undesirable biomass can be effectively separated from the bagasse and could be utilized as a source of fuel partially or wholly replacing the requirement of fossil fuels in the sugar mills. The other useful fractions of bagasse obtained as fibrous biomass devoid of pith or with a small quantity of pith which are ideal and suitable for manufacture of quality paper and medium density fiber board and particle board. BACKGROUND OF THE INVENTION
Bagasse has been used for paper making in many countries of the world as it offers the advantage of being a quality, renewable material. Bagasse is the waste material left after the crushing operations in the sugar mills producing sugar from sugar cane. This bagasse, which is a potential raw material for the paper, particle board and MDF industry, has a very serious drawback. Along with the fibrous portions of the bagasse, there is pith, which is undesirable from the point of view of the paper and board making processes.
The presence of pith in the bagasse has several adverse effects on paper making processes such as high chemical consumption, quality related problems, runnability problems on the paper machine coupled with serious environmental problems. Likewise, in case of manufacture of MDF, impure fiber containing pith and other undesirable materials cause quality related problems besides higher chemical consumption.
Thus, there exists a need for a process for the efficient removal of this pith from the fibrous portion of bagasse so that the same can be used for pulp and paper making in an efficient and better manner. Research work has been going on for producing efficiently depithed bagasse since the early 1900s. Many US patents disclose various processes for depithing bagasse. The prior art depithing processes are mainly related to methods which use moist depithing or a combination of the moist and wet depithing. In both the processes, bagasse is mechanically abraded to break the clusters of pith away from the remaining fibrous portion of bagasse. Dry depithing process is accomplished by using a hammer mill followed by dry screening.

In wet depithing process, a suspension of previously moist depithed bagasse is made in water at around 3-5% consistency, wherein a portion of the pith present in the moist depithed bagasse is separated by utilizing the difference in the densities of the fiber and pith. Moist depithing involves direct depithing of bagasse after crushing at moisture of around 50%. The previous efforts for the improvement of the design and processes of depithing have continued so as to achieve at a process which yields efficiently depithed bagasse with a better quality of fiber which proves more useful for paper making.
In the prior art, the moist depithing has been reported to remove 30-60% of the total pith content in bagasse with a residual pith content of 18-20% as against 30-35% in the whole bagasse. In fact, the removal of pith up to 50% can be achieved by two stage depithing consisting of moist depithing process in combination with the wet depithing process. Wet depithing process uses an aqueous solution of partially depithed bagasse obtained by the moist depithing procedure. In the wet depithing process, the moist depithed bagasse is diluted with water to make slurry of around 3% prior to the depithing procedure. Even with the combination of the moist and the wet depithing technology, a pith removal of more than 50% has been difficult to obtain. However, the best figures of removal have been reported to be up to 70% by using the combination of moist and wet depithing which not only involves two step operations but is highly capital and energy intensive process. The residual pith content in the depithed bagasse is not less than 15% as against the pith content of-35% in the bagasse generated in the sugar mills. The resultant depithed bagasse sample by this method has a fiber to pith ratio of not more than 3:1. Further the wet pith obtained in the depithing operations is difficult to be handled and causes severe problem of liquid and solid waste disposal.
As of date, the above and a plethora of other bagasse depithing technologies have been developed from time to time with the sole objective of improving the removal efficiency of pith from bagasse. However, to the best knowledge of the inventors, their has been no technology that could remove the pith from the bagasse in excess of 50% in a single dry step process thereby the depithed bagasse shall contain a residual pith content of more than 16-18%.
In another field of cereal grain processing, there was a tradition of using rotatable mill stone with a circular working surface for grinding. The development of the disk mill technology from this stage onwards has been described in US Patent 4667888 (Andersen). The said patent was covers the design of a disk mill for the processing of cereals, seeds or like products to effect the separation of these items in to their botanical components so as to yield a siftable material, which could be fractionated in to the desired fractions. This patent describes
a machine that has been optimized for use with cereals to produce flour and other intermediate products.
In US Patent 5186989 (Wellmcm) the disk milling procedure was integrated with the cleaning of wheat wherein it is used after the bran removal step. Wellman also discusses the prior art for wheat and cereal treatment in detail. The design of the Wellman's disk mill was markedly different from Andersen's though essentially performing the same functions on the debraned wheat. Thereafter. Wellman was granted one more patent in 1993 (US Patent 5211343) for the process of milling cereal grain to produce flour and other intermediate products. The disk mill in this case was used in conjunction with roller mills to treat cereal grain.
Hereinafter, reference is made to the patents TR 9701402T, WO9637305 and EP 0828 561 Bl granted to M/S United Milling Systems, Denmark for a design which can best be described as a improved version of the Andersen design. The disk mill therein has again been used in conjunction with various other devices for the treatment of wheat cereal for the production of different white flour fractions.
Other patent documents which describe the state of the art are US Patent 4369545 (Jan' 983, Malinak); US Patent 464P92 (Feb" 1987. Villavicencio); US Patent 5266161 (Nov' 1993, Kroeker); US Patent 6435433 (August" 2002. Hesch).
Based on the foregoing, and to the best knowledge of the inventors, the above two branches i.e. bagasse depithing and the short milling technology using disk mill have remained exclusive of each other.
The preferred embodiment of the present invention relates to an apparatus having a design optimized for treatment of bagasse so as to obtain a siftable mass that could be sifted using a separation device to obtain desired fractions containing the pith, medium and large rind fiber. The fibers obtained from the system has a pith content of not more than 10%, which is a significant improvement over the prior arts. OBJECTS OF THE INVENTION
The primary object of the invention is to provide for an improved apparatus and method for the treatment of raw material to obtain a sift able product for use in paper industry.
Another object of the invention is to provide for an improved apparatus and method for the treatment of bagasse, a waste material left after the crushing of sugar cane in the sugar mills so as to obtain a sift able biomass wherein the pith, and undesirable biomass can be effectively

separated from the bagasse and could be utilized as a source of fuel partially or wholly replacing the requirement of fossil fuels in the sugar mills.
Yet another object of the present invention is to provide for an improved apparatus and method to obtain other useful fractions of bagasse obtained as fibrous biomass devoid of pith or with a small quantity of pith which are ideal and suitable for manufacture of quality paper and medium density fiber board and particle board.
Another object of the invention is to provide for an apparatus having a design optimized for treatment of bagasse so as to obtain a sift able mass that could be sifted using a separation device to obtain desired fractions containing the pith, medium and large rind fiber; so that the fibers obtained from the system has a pith content of not more than 10%. SUMMARY OF THE INVENTION
Accordingly, the present invention relates to an apparatus for treating raw material comprising:
(a) a feeder assembly for receiving and feeding the raw material to be treated;
(b) a milling system [E] having a treatment chamber to which the raw material is fed, comprising a pair of optimally designed discs [edr, eds] having adjustable space in between, wherein one of the disk is stator [eds] and the other is rotary [edr];
(c) an impeller [id] attached to the rotary disk [edr];
(d) a separating/sieving system [G] comprising a universal separator, an inlet to the separator and the brush auger assembly having optimized openings spaced at equal distance for sifting the treated raw material.
In a preferred embodiment, the apparatus of the invention uses raw material selected from the group comprising straws, bagasse, grass, cotton linters, cotton rags, linen, hemp, manila and other agro based fibrous material.
In accordance with the embodiments of the invention, said feeder assembly comprises: (i) one or more hoppers [A] for receiving the raw material, (ii) a conveying system [B.C] for transporting the raw material from the receiving hopper
[A] to the feeder hopper [D]: (iii) feeder hopper [D] for feeding the raw material to the milling system [E].
In accordance with the embodiments of the invention, the said milling system [E] is a disk mill comprising the said treatment chamber which is an assembly of disks [eds, edr], grinding/treatment elements, a gap adjustment mechanical system, a shaft, an impeller [id], all

connected to each other and the said assembly mounted such as hereinbefore described in a casing, wherein the said casing is preferably a welded steel profile frame.
In accordance with the embodiments of the invention, the said rotary [edr] and stator [eds] discs of said milling system [E] comprises optimally designed grinding/treatment elements [ede(II)] attached on the periphery of the said discs [eds. edr] by attaching means at an specified angle [a°j.
In accordance with the embodiments of the invention, the said rotary [edr] and stator [eds] discs of said milling system [H| are preferably vertically mounted in the said treatment chamber, preferably inside a housing that can be opened as and when required for cleaning and servicing purposes.
In accordance with the embodiments of the invention, the said attaching means are two screws per grinding/treatment element fede(II)] having specified internal diameter [edei] and external diameter [edeo]. and are placed at an appropriate distance so as to properly fix the grinding/treatment element [ede(II)] to the discs [eds, edr].
In accordance with the embodiments of the invention, the said grinding/treatment elements [ede(II)] have an optimized design of alternating teeth and groves forming a pattern of ridges, wherein the teeth are tooled off to obtain a flattened surface, providing a brushing action therefor.
In accordance with the embodiments of the invention, the said teeth and groves of said grinding/treatment elements [ede(Il)] are either parallel to the left edge or to the right edge of the element at an specified angle [edela0].
In accordance with the embodiments of the invention, the said the grinding/treatment elements [ede II] are [edel] in width at the top and [ede3] wide at the bottom.
In accordance with the embodiments of the invention, the distance between two successive edges on each grinding/treatment element [edell] is [ede4], distance between two successive edges on each grinding/treatment element at the top edge same is [ede5], depth of the groves in the said elements is [ede8] and angle between two successive groves is [edeta] degrees.
In accordance with the embodiments of the invention, the said stator disk [eds] has a central circular hole [eds5].
In accordance with the embodiments of the invention, the said rotary disk [edr] is mounted on a shaft, wherein further the said shaft is mounted in a cast iron housing supported by double ball bearing inserted in the space [edr 17] of the rotary disk [edr].

In accordance with the embodiments of the invention, an impeller [id] is connected with the base of the said shaft.
In accordance with the embodiments of the invention, the the said impeller [id] having a diameter [id5] to fit on the rotor, curved veins at an angle of [b] degrees, each curved blades [id2] long and [idl] wide, wherein the curvature of the impeller blades is at an radial angle of (rdl°).
In accordance with the embodiments of the invention, the said separating system [G] receives the siftable bagasse into the said universal separator consisting of a brush auger and sieves which separates the pith from the fibrous portion of the bagasse.
In accordance with the embodiments of the invention, the said separating system [G] is [gl] in height and [g2] in breadth, the outer casing of the auger brush is [g7] in diameter, the auger brush is [g7] in diameter and wherein the said brush is propelled by a motor.
In accordance with the embodiments of the invention, the separated pith and fibrous material falls though the sieves by gravity and is collected separately with the help of hoppers at the bottom of the said separating system [G].
The present invention also relates to a method for method for the treatment of raw/waste material to obtain a sift able biomass wherein the pith and undesirable biomass can be effectively separated from the raw/waste material comprising:
receiving the raw material in a receiving hopper with adjustable opening(s);
conveying raw material from hopper opening to preferably by a conveyer;
optionally subjecting the raw material to magnetic separation by positioning magnetic
separation above the moving conveyer to remove any metallic parts/impurities;
supplying the raw material to a feeder hopper under the influence of gravity;
feeding the raw material from feeder hopper into disc gap of the treatment chamber of the
disk mill with the help of a specially designed impeller connected with the base of the shaft;
regulating the rate at which raw material is fed as per the need/nature of the raw material;
the proper entry space of the raw material is maintained with the help of a gap adjustment
mechanical system for giving maximum defiberization and is varied with respect to the
quality, type and moisture content of the raw material being used for depithing;
imparting maximum brushing action and minimum cutting action to the raw material to
dislodge maximum pith;
collecting the treated siftable substrate under the influence of gravity;
subjecting the collected treated siftable substrate to separation in the separating system;
separating the outlet treated siftable substrate into the separated fractions.

In a preferred embodiment, the raw material used in method of the invention is selected from the group comprising straws, bagasse, grass, cotton linters. cotton rags, linen, hemp, manila and other agro based fibrous material.
In another preferred embodiment, the said raw material used in method of the invention is bagasse and the said separated fractions comprises of three fraction, wherein the first fraction is pith, the second is the short fiber and the third fraction is made up of the long fibers. BRIEF DESCRIPTION OF THE DRAWINGS ACCOMPANYING THE PROVISIONAL SPECIFICATION FIGURE 1: is an illustrative schematic diagram depicting the procedure for the depithing of
bagasse. FIGURE 2: depicts the plant set up for the depithing of bagasse. FIGURE 3[ede (I)]: This figure gives out the manner in which the grinding elements are fixed;
the angle alia (a) is a function of the number of grinding elements fixed on the
disk. For example, in the present case, the use of 24 elements means that this
angle will be 15 degrees (24 x 15 = 360). FIGURE 4[ede (II)]: is an exploded view of the grinding element used in the milling
operation. The dimensions of the grinding element have been optimized to give
the desired action to the incoming bagasse so as to obtain the desired quality of
output. FIGURE 5[eds]: is diagrammatic representation of the STATOR used in the milling system. FIGURE 6[edr]: is diagrammatic representation of the ROTOR used in the milling system,
wherein the shaft is inserted in the space marked edrl7 and the impeller is fixed
between the space edrl3 and edrl4. FIGURE 7 [id]: is an exploded view of the specially designed impeller.
BRIEF DESCRIPTION OF THE DRAWINGS ACCOMPANYING THE COMPLETE SPECIFICATION
The following drawings accompanying the complete specification are same as submitted with the provisional, only the Figures are allotted sub-numbering for more clarity: FIGURE 8a and FIGURE 8b: FIGURE 8a is a cross section (front elevation view) of the disk
mill and FIGURE 8b is the front view of the disk mill. FIGURE 9a, FIGURE 9b and FIGURE 9c: Figure 9 is the engineering drawing of the
separating system used to separate the treated bagasse into the desired fractions.
FIGURE 9b gives the specifications of the universal separator. FIGURE 9a gives

the specifications of the inlet to the separator. This is a part of the separator itself but needs separate detailing as this is vital to the working/fabrication of the universal separator. FIGURE 9c gives the specification for the drive of the auger brush (depicted by dotted line in the center figure) in the separator. DETAILED DESCRIPTION OF THE INVENTION
The present invention relates to the designing of an apparatus for treating bagasse to disintegrate it further in to its botanical components to give a suitable product wherein the useful fibrous portion is separated from the pith portion of bagasse by a suitably designed and optimized machine composed of milling and separating system consisting of a disk mill and brush augur assembly with optimized openings spaced at equal lengths below the assembly to effect sifting of the treated bagasse to obtain useful fractions of fibrous mass.
The said apparatus with the optimized design contains optimally designed elements fixed on the periphery of a stationary disk and a rotary disk connected to a suitable motor with the usual fittings for mounting of the shaft and connection of the motor to the shaft. The grinding elements have optimized alternating patterns of teeth and grooves thereby forming a pattern of ridges. The edges of such ridges have been tooled off to give the optimum brushing action to the bagasse to give an optimally siftable product. The grooves and teethes on the elements are either parallel to the left edge of the element or the right edge and are used as per need. There is a specially designed impeller mounted on the inside of the rotating shaft which has been optimized to distribute the material evenly between the two disks and to improve the throughout put of the machine.
In the said apparatus each of the treatment elements (Figure 4) are edel in width at the top and ede3 at the bottom. The treatment elements in the apparatus are ede2 having two sink screw holes at appropriate distances with internal and external diameter of edei and edeo respectively. The distance between two successive edges on each element is ede4 and the top edge of the same is ede5. The depth of the grooves in the elements is ede8. The angle between two successive grooves is edeta degrees.
In the preferred embodiment of the invention the apparatus has two sets of grinding elements. One set of elements have the grooves parallel to the left edge of the element and the other has grooves parallel to the right of the element, at an angle plus or minus edela degrees as the case may be. These are used on the rotor or stator as per the need, optimally the elements with the same inclination of the ridues are on the same disk.

The stator [eds] and rotor [edr | disks are crafted to hold the elements in place by the use of two counter sunk screws per element. The rotor disk (Figure 6) is edr 11 in diameter having a thickness of edr4 the provision of holes with suitable diameter for two counter sunk screws to fit the grinding elements. All the other dimensions shown in Figure 6 [edr] have been proportionately designed to ensure the best fit of the grinding elements on the disks, the proper entry space of the raw material in to the disk, the fitting of the shaft and the insertion of an impeller with curved veins to push the bagasse towards the disk gap for defiberization. The stator disk (Figure 5) is similar to the rotor disk in all respects save the fact that it has a central circular hole (eds5). The side view and the front views of the two disks [edr. eds] mounted on a shaft using suitable matching base supports in a casing are depicted in Figure 8 (the dimensions of the same are indicated on the figure). The inlet with a diameter oft'-/ feeds in the material to the disks. The outlet of the disk mill is e7 long and eI3 broad. The other dimensions are proportioned for the machine stability and smooth operation. The gap between the rotor and the stator is adjustable as per need.
The material enters the center of the rotary and stationery disk under the influence of impelling force given to it by the impeller (Figure 7) connected on to the rotor and is treated by a brushing action between the two sets of elements.
The diameter of the impeller (Figure 7) fits on the rotor is (id5) with curved veins put at an angle of b degrees. The length of each of the curved blades on the impeller is id2. The curvature of the impeller blades subtends a radial angle of rdl °. The width of each impeller blade is ibl. After the treatment a siftable mass is obtained, which is then led on to the separating system. The treated raw material is sifted in to various fractions using a brush assembly (Figure 9). The assembly is gl high and g2 broad. The outer casing of the auger brush is g7 in diameter and the diameter of the brush is g8. There are three outlets to the bottom of the assembly. There is a provision for fitting of screens in the bottom of the assembly as per requirement. The openings of the screens used have been optimized in diameter and length from the material inlet to the outlet as discussed above.
The preferred embodiment of the present invention is structured for the treatment of bagasse at the sugar mill site. At present, the sugar mills use the bagasse to generate energy through the co-gen route, burning the useful fiber in the process, which otherwise is an important fibrous source for the paper industry. Thus only the surplus bagasse left with the sugar mills along with undesirable pith after meeting out the in house energy requirements of the sugar mills is transported to the paper mills. It can be seen that when transporting the whole bagasses to the paper mill, actually 30-35% of the waste material is being transported, which in

any case is separated at the paper mill site and is a source of pollution. If the pith is separated using the method and apparatus of the invention, nearly 30-35% of the whole bagasse removed as pith shall be available in a dry form at the sugar mill site for use as a fuel. In fact, the use of the partially dried pith offers a potential to have surplus efficiently depthed bagasse to be used as fibrous raw material source turned free for its use in the paper mill.
The middle fraction, obtained from the method and apparatus of the invention as described above is also devoid of any pith and forms a ready hand dry substrate for the manufacture of high quality medium density board (MDF) and particle board.
The remaining 50% of the material shall consist of long fiber almost devoid of pith (residual pith <10%). relatively dry substrate, optimally suitable for paper making. This fibre shall have no more than 10% pith. The comparison between the paper made by the bagasse depithed by the conventional process and that obtained by the method and apparatus of the invention are enumerated as follows.
1. The bagasse fiber obtained by the method and apparatus of the invention results in a lower demand of the chemical by 10%. which has a down the line positive synergistic effect in reducing the pollution loads and increasing the product quality.
2. The key characteristics of paper made out of bagasse depithed by method and apparatus of the invention are better that the paper made out of bagasse depithed conventionally. Remarkable improvement in seen in the physical properties such as burst, tear and opacity.
3. The black liquor, obtained by the pulping of depithed bagasse as per method and apparatus of the invention has superior properties with respect to the Swelling Volume Ratio, (SVR) and viscosity. The viscosity reduces by over 50%. indicating the possibility of firing of the black liquor at higher solid content, thereby improving the energy efficiency of the recovery boiler.
4. There is a remarkable improvement in certain combustion characteristics of the black liquor, obtained from bagasse fibers depithed as per method and apparatus of the invention in the chemical recovery street. The SVR improves from a value of 10 to 15 and the black liquor exhibits an improved combustion profile.
5. The quality of fiber obtained by the method and apparatus of the invention, when used for making paper pulp had advantage over the depithed bagasse from prior arts in respect of savings in cooking chemicals, gain in pulp yield besides lowering the environmental impacts by way of reduction in liquid and solid waste pollution. Further the middle fraction has excellent use in the manufacture of MDF.

The process of this invention presents a new. highly efficient system for the processing of paper making raw material such as bagasse (a waste leftover from the crushing operation in the sugar industry) so as to obtain a fibrous bagasse portion having a residual pith content of no more than 10%.
The schematic diagram of the depithing process as disclosed herein is depicted in Figures 1 and 2. At the outset, the bagasse obtained either directly from the crushing operations in the sugar mill or from a storage yard in the paper/sugar mill is put in to a vibratory hopper [A] fitted on top of a conveying system, such as a conveyer belt [C]. If desired, a magnetic separating system may be placed above the conveyor belt to remove any metal contaminants from the bagasse. The function is important if de-bailing operations are used as no metallic impurity should be allowed to enter the system. However, in case the machine is used at the sugar mill site and there is no possibility of metal intrusion, the same can be dispensed with. The conveyor belt [C]. driven by a motor [B] leads the whole bagasse in to a screw conveyer [at D] on top of the disk mill. The material comes off the conveyor belt and falls in to the small screw conveyer, which feeds the bagasse in to the disk mill [E] by gravity. After the treatment, the siftable material obtained is led in to a cyclone [F], which separates out the fines and dust obtained during the process. The outlet of the cyclone bottom is fed in to the sifting device [G] directly. In case the operations are being carried out at a sugar mill site, the use of the cyclone is optional, as the treated material can be made to pass in to a silo or a storage heap as such a space is normally available at sugar mill sites.
The treatment chamber of the disk mill consists of a pair of vertically mounted metallic disks to which the bagasse is fed at a constant rate, which can be adjusted as per the need of the raw material, i.e. based on the gap between the disks and the moisture content of the input bagasse. One of these disks is stationary and the other is rotary. The balanced rotating disk is mounted on a shaft with a friction brush assembly. The shaft is mounted in a cast iron housing supported by double ball bearing. The stator and rotor disks are crafted to hold the elements in place by the use of two counter sunk screws per element. The rotor disk (Figure 6) is edrll in diameter having a thickness of edr4 the provision of holes with suitable diameter for two counter sunk screws to fit the grinding elements. All the other dimensions shown in Figure 6 have been proportionated to ensure the best fit of the grinding elements on the disks, the proper entry space of the raw material in to the disk, the fitting of the shaft and the insertion of an impeller with curved veins to push the bagasse towards the disk gap for defiberization. The

stator disk (Figure 5) is similar to the rotor disk (Figure 6) in all respects save the fact that it has a central circular hole (eds5).
The side view and the front views of the two disks mounted on a shaft using suitable matching base supports in a casing are depicted in Figure 8. The dimensions of the same are indicated on the figure. The inlet with a diameter of e4 feeds in the material to the disks. The outlet of the disk mill is e7 long and el3 broad. The other dimensions are proportioned for the machine stability and smooth operation.
There are specially designed milling components i.e treatment elements fixed along the periphery of both the disks. Each of the treatment elements is fixed on to the disk using a groove-screw method at two places.
The diameter of the disks and the size of the treatment elements fixed on the disk are a function of the size and throughput desired from the apparatus/set up. The disks are mounted inside a housing that can be opened as and when required for cleaning and servicing purposes. In any case one treatment elements is placed at every a° on the disk (Figure 3). The length and width of the milling component is fixed to an optimized scale, depending on the diameter of the disks which may be increased to fabricate a larger machine.
The gap between the rotating and the stationary disk is adjusted by means of a mechanical system; The said gap is optimized to give maximum performance and is varied with respect to the quality, type and moisture content of the raw material being used for depithing. The whole assembly of the disks and the gap adjustment mechanism are mounted on a suitable welded steel profile frame.
The incoming raw material is forced in to the disk gap evenly with the help of a specially designed impelling surface connected with the base of the shaft. The diameter of the impeller (Figure 7) fit on the rotor is id5 with curved veins put at an angle of b degrees. The length of each of the curved blades on the impeller is id2. The curvature of the impeller blades subtends a radial angle of rdl °. The width of each impeller blade is ibl.
The raw material is subject to mechanical action by the treatment elements on the rotating and fixed disks. Each of the treatment elements (Figure 4) are edel in width at the top and ede3 at the bottom. The elements are ede2 having two sunk screw holes at appropriate distances with internal and external diameter of edei and edeo respectively. The distance between two successive edges on each element is ede4 and the top edge of the same is ede5. The depth of the grooves in the elements is ede8. The angle between two successive grooves is edeta degrees . There are two sets of grinding elements. One set of elements have the grooves

parallel to the left edge of the element and the other has grooves parallel to the right of the element, at an angle plus or minus edela degrees as the case may be. These are used on the rotor or stator as per requirement, optimally the elements with the same inclination of the ridges are on the same disk. The stator and rotor disks are crafted to hold the elements in place by the use of two counter sunk screws per element.
During this process, the necessary action is given to the bagasse, so that maximum pith is dislodged with minimum effect on the quality of the fiber i.e. the design of the elements is so optimized so as to impart maximum brushing action and the least cutting action to the bagasse fibers. After this process, the treated bagasse comes out of the disks and falls down under the influence of gravity. The extent of grinding is determined by the type and the nature of the feed raw material, its moisture content, the distance between the surfaces of the disks, the design on the surface of the treatment elements.
After the milling action, the treated siftable substrate comes out of the system due to the centrifugal force and falls dovvnwards under the influence of gravity. However, this mass has a considerable velocity which needs to be reduced for further processing. Hereinafter there are two ways of handling the substrate. When the processing is being done in a sugar mill, where the bagasse is relatively wet. the siftable material may be let in to a silo where the material is collected and led in to the sifting device, viz. a brush auger separator. When the device is to be put up in a small area and if the bagasses is relatively dry. it is desirable to use a suitably designed cyclone after the disk mill, which not only acts as a pressure reducing device but also separates out the very fine dust from the material.
Subsequently, the siftable bagasse is made to fall in to a specially designed apparatus consisting of a brush auger and sieves which separates the pith from the fibrous portion of the bagasse. In this apparatus, brush auger and sieve assembly (Figure 9) the treated bagasse is made to pass over a series of sieves with the help of an endless rotating auger brush, which cleans the screens/sieves as it moves the treated material above them, thereby aiding effective separation of the pith and the fiber. The assembly is g1 high and g2 broad. The outer casing of the auger brush is g7 in diameter and the diameter of the brush is g8. There are three outlets to the bottom of the assembly. There is a provision for fitting of screens in the bottom of the assembly as per need. The openings of the screens used have been optimized in diameter and length from the material inlet to the outlet.
The endless brush is propelled by a suitable motor. The separated pith and fibrous material falls though the sieves under the intluence of gravity and is collected separately with the

help of hoppers at the bottom of the sieves. The positioning of the sieves and the opening per linear inch is optimized to separate out the pith from the fibrous portion of bagasse.
The method and apparatus herein described is a significant improvement over the conventional methods for the depithing/treatment of fibrous raw material. As of now, conventional methods such as dry/moist depithing and combination of moist and wet depithing are used to separate the pith from the bagasse. At best, these methods are able to give a clean raw material which still has a residual pith content of not less than 12% , and that too by using the best commercial technology available today, i.e. the combination of dry and wet depithing, involving two operations. In this case, the other disadvantage is that the pith obtained as a wet slurry is difficult to be disposed off creating a sever problem of pollution. DETAILED DESCRIPTION OF PREFERRED EMBODIMENT OF THE INVENTION
FIGURE 1 is an illustrative schematic diagram depicting the procedure for the depithing of bagasse. Normally in Indian conditions, bagasse is received in a hopper to start with. This hopper actually makes the bagasse flow on the moving conveyor. By adjusting the opening of the hopper the feed rate of the bagasse going on the conveyer can be controlled. The magnetic separators have been indicated with the conveyer belt. They are to be positioned above the moving conveyer to remove any metallic parts that may have come with the bagasse. This is needed more in case if the bagasse is obtained in bails wherein in wires are used to tie up the same. During the debailing process, some wire/metallic sundries may be left over in the bagasse sample. The magnetic separator removes them. In case the equipment as described in the claims is used directory at sugar mill site, and if one is sure that no metal pieces can enter the bagasse, the magnetic separator can be done away with. The conveyor belt drops the bagasse in to a feeding device which actually pushes the bagasse in to the disk mill. Now this can be any device. We have used a small screw conveyor in the feeding device to make the bagasse fall in to the disk mill under the force of gravity. The disk mill [E] is described in detail subsequently. The separating system indicated is also described in detail later. The bagasse as obtained from the separation system is obtained as three fractions - the first fraction is pith, the second is the short fiber and the third fraction is made up of the long fibers.
FIGURE 2 depicts the plant set up for the depithing of bagasse. The description of the reference numerals as given in this figure are as under:
A: Hopper for feeding bagasse on to conveyor belt; B: Conveyor pulley motor stand; C: Convever:

D: Feed hopper (where the bagasse is made to fall, just prior to entering the disk mill:
E: Disk mill:
F: Cyclone separator (this equipment is routinely used for particulate emission control: it is a system used to trap very fine particulate matter from getting air borne:
G: Separation unit (it separates treated bagasse in required fractions;
H: Blower (part of the cyclone separator). FIGURE 3 [ede (l)|gives out the manner in which the grinding elements are fixed; the angle alfa (a) is a function of the number of grinding elements fixed on the disk. For example, in the present case, the use of 24 elements means that this angle will be 15 degrees (24 x 15 = 360).
FIGURE 4[ede (II)| is an exploded view of the grinding element used in the milling operation. The dimensions of the grinding element have been optimized to give the desired action to the incoming bagasse so as to obtain the desired quality of output. The description and dimensions of the reference numerals used in the figure are as under, however a 10-15 proportionate change in dimensions will also give similar results and is well with in the scope of the invention:
REFERENCE NUMERALS ede(II) VALUE IN MM
edel 61.2
ede 2 87.4
ede3 39.1
ede i 6.0
edeo 12.0
edeta about 45 degrees
ede 4 2.0
ede 5 0.5
ede 6 6.0
ede 7 62.0
edela about 70-80 degrees (is determined
by above dimensions)
FIGURE 5[eds]is diagrammatic representation of the STATOR used in the milling system.
The description and dimensions of the reference numerals used in the figure are as
under:
REFERENCE NUMERALS eds VALUE IN MM
edsl 510
eds2 437
eds3 349

eds4 305
eds5 202
eds6 880
eds7 13
eds8 0.3
eds9 0.8
edslO 440
FIGURE 6[edr] is diagrammatic representation of the ROTOR used in the milling system, wherein the shaft is inserted in the space marked edrl7 and the impeller is fixed between the space edrl3 and edrl4. It is being mentioned here for the sake of clarity that the dimension of the rotor as used/described herein is based on the size of the disk mill. If, a larger machine is to be built, a larger rotor will have to be fabricated. The proportions of dimensions may be used if so desired. The dimensions given herein are the actual dimensions of the preferred embodiment of the invention. A larger/smaller with accordingly increased/decreased dimensions will also give the same results and is well within the scope of the invention. The description and dimensions of the reference numerals used in the figure are as under:
REFERENCE NUMERALS - edr VALUE IN MM
edrl 436
edr2 88
edr3 14
edr4 30
edr5 6
edr6 2
edr7 47
edr8 169
edr9 83
edrlO 73
edrll 510
edrl 2 350
edrl 3 293
edrl 4 203
edrl5 118
edrl 6 108
edrl7 65
edrl 8 10
edrl9 6

FIGURE 7[id] is an exploded view of the specially designed impeller. The description
and dimensions of the reference numerals used in the figure are as under:
REFERENCE- NUMERALS id VALUE IN MM
rdl 10
idl 10
id2 45
id3 10
id4 20
id 5 200
id6 30
FIGURE 8a and FIGURE 8b: FIGURE 8a is a cross section (front elevation view) of
the disk mill and FIGURE 8b is the front view of the disk mill. The description and dimensions
of the reference numerals used in the figure are as under:
REFERENCE NUMERALS VALUE IN MM
el 310
c2 60
e3 200
e4 120
e5 45
e6 90
e7 140
e8 580
e9 100
elO 240
ell 110
el2 780
c13 260
FIGURE 9a, FIGURE 9b and FIGURE 9c: Figure 9 is the engineering drawing of the
separating system used to separate the treated bagasse into the desired fractions. FIGURE 9b
gives the specifications of the universal separator. FIGURE 9a gives the specifications of the
inlet to the separator. This is a part of the separator itself but needs separate detailing as this is
vital to the working/fabrication of the universal separator. FIGURE 9c gives the specification
for the drive of the auger brush (depicted by dotted line in the center figure) in the separator. It
is mentioned for sake of clarity that the dimension of the separator as used herein is based on
the size of the plant and does not have any bearing on the specifications. If, for example, a
larger machine has to be built, a larger separator will have to be fabricated. The proportions of

dimensions provided herein may be used if so desired, which is well within the scope of the
invention. An oversize separator may be used keeping in mind future requirements/shock loads.
The description and dimensions of the reference numerals used in the figure are as under:
REFERENCE NUMERALS VALUE IN MM
gl I960
g2 920
g3 280
g4 180
g5 280
g6 120
g7 570
g8 320
g9 50
gl0 271
g 11 240
g12 145
gu 120
gl4 180
gl5 120
g 16 240
g 17 80
gl8 1700
g19 107
g20 561
g21 370
g22 413
EXPERIMENTS AND OPTIMIZATION STUDIES EXAMPLE i. CONTROL SAMPLES
To begin with the depithing trial experiments with the new proposed depithing process and apparatus of the invention, all the three different samples of bagasse viz. the whole bagasse sample, depithed bagasse samples obtained from moist depithing operation and a combination of moist and wet depithing operation were analyzed for the parameters of interest.
The water-soluble content and the useful fiber content in the samples under test are determined by following the standard TAPPI procedure T-230cm-99.
To determine the pith content, the test sample of 1% consistency was disintegrated for 30 minutes in British Pulp Disintegrator by using 2500 ml of water. This sample was transferred on a

300-mesh sieve and washed under running water. The substrate retained on the mesh was disintegrated again by following the same procedure as descried above. The pith material passing though the sieve in both cases was collected on a muslin cloth. Both the fibrous portion retained on the mesh as well as the pith collected in the muslin cloth were dried in an oven at 105 ± 1 °C. The fibre and the pith content were calculated on a weight percent basis.
Table 1 gives a comparative study of the analysis of samples of bagasse as obtained by the conventional depithing process with the proposed apparatus and method. The composite samples of the moist and the combination of moist and wet depithed bagasse were collected from a paper mill and preserved in poly bags for shipment. These samples were analyzed for the characteristics of interest with the least possible lag time using the procedures described earlier. The determinations were carried out in triplicate and the values obtained are presented in the table.
TABLE -1
COMPARATIVE RESULTS OE DEPITHING AMONG THE CONVENTION DEPITHING PROCESS AND THE NEW DEPITHING METHOD AND APPARATUS
(Table Removed)
Table-1 compares the bagasse samples obtained after depithing by the best available present methods with the depithed bagasse using the method of the invention having 50% initial moisture. As seen from the above results, even the lowest values of useful fiber to pith ratio obtained by the present proposed method as described in claim 1-15 are substantially higher at around 18:1 as compared with the best value of 8:1 obtained for depithed bagasse by the present art of depithing.

TABLE -2
COMPARISON OF THE CAIN IN PROPERTIES BETWEEN THE ELEMENT DESIGN OF THE PRIOR ART AND THE ELEMENTS OF THE PRESENT DESIGN
(Table Removed)

Further with the design of the machine as per the prior art, frequent jamming of the disk was observe! even when the feeding rates were lowered. Further, in the prior art, the grinding elements wc.v short in length with sharp edges providing more cutting action than brushing action, as the machine was designed primarily for the treatment of cereal grains. When this machine is used for the treatment of bagasse, due to the cutting action, the middle fractions obtained are mixed with pith and as such are not of the required quality for appropriate end use.
EXAMPL 2. CHARACTERIZATION AND COMPARISON OF PULP QUALITY OF DEPIT1IE1) BAGASSE FROM CONVENTIONAL MEANS AND BY THE APPARATUS AND METHOD OF THE INVENTION
To compare the performance of the depithed bagasse obtained from conventional
methods and by the proposed new method and apparatus, a lab scale pulping operation was
performed under normal conditions employed in pulping operations in order to ascertain the
advantage of the efficient depithing by the proposed new methodology as described herein. The
pulping experiment done with all the three different bagasse samples containing various
proportions of residual pith obtained by conventional depithing processes viz. dry /moist
depithing process, combination of dry and wet depithing and the new proposed depithing
operation ;. described hereinbefore. The bagasse sample obtained by conventional dry/moist
depithing, combination of moist and wet depithing and that obtained by the present invention
had a residial pith content of 25%. 12% and nearly 5% respectively. The results of this
experimenture summarized hereunder. All trials were carried out in triplicates.
EXPERIMENT-3 A
Pulping conditions: Sul tidily : 17%
Bath Ratio : 1:3.5
Temperature : 16()°C'
Time : 60 minutes
Alkali charge : 17%

(Table Removed)

EXPERIM. MT-3B
Alk .li Charge 20%
(Table Removed)

From the above results it is clearly seen that the pulp obtained from the new depithing method and apparatus described in the present invention, showed higher viscosity values with a better cell..lose content as well as higher screen pulp yields. The pulp thus obtained by the improved method and apparatus depithing of the present invention is better for value added
product.
Direct benefits accrued from the new proposed depithing method and apparatus:
As per the pulping and bleaching experiments carried out, with depithed bagasse obtained from the new proposed method of depithing and its comparison with the conventional best available depithing technology (wet depithing process), the benefits accrued for 100 TPD pulp production are placed below while maintaining the similar kappa number(7.8) and viscosity levels (19 cps) ('1 able-/!).
TABLE-3
CHEMICAL SAVINGS BY DISC MILL DEPITHING

(Table Removed)
Pulp yield
The yield of dcpithed bagasse obtained from the proposed method is about 2% more than that obtained by conventional method ie net gain of 4 ton pulp for 100 TPD pulp production while maintaining the similar kapp number and viscosity of the pulp at comparable levels (19cps)
Savings in chemicals
The chemical ;ised for cooking of the depihted bagasse from the proposed method is also
around 2% lower (ca 18% alkali charge used in place of 20% for the conventionally depithed
bagasse i.e. net savings of 5.6 tons of cooking chemicals (Caustic soda) for 100 TPD pulp
production.

IMPROVEMENT IN VISCOSITY PROFILE
In an effort to exhibit the gain in the properties of the viscosity profile of the black liquor obtained from puling the depithed bagasse as per the method in claim 1-15 an experiment was carried out wherein the viscosity profile of the black liquor was determined as a function of the increasing solid content.
Sample Treated at a gap of 3mm
Residual Pith content of the sample so obtained 8%
(Table Removed)

* Note:- Viscosity in mPa..s
Sample Treated at a gap of 7mm
Residual Pith content of the sample so obtained : 20.18 %
(This would be the nominal pith content of the bagasse depithed by the conventional means)
Sample :
Pith content:- 20%
(Table Removed)
* Note:- Viscosity in mPa..s

The above profile of the two samples clearly depicts a marked improvement in the viscosity profile of the bagasse black liquor obtained from depihted bagasses wherein a drastic reduction in the viscosity of the black liquor was noticed which was reduced to around 400 at 70% solids at a temperature of around 95 degree centigrade and making it possible to fire the black liquor at high dry solids that is 70% thereby increasing energy efficiency in the chemical recovery system. It is worth while to mention here that the black liquor resulting from the pulping of depithed bagasses resulting from the conventional depithing processes normally have a viscosity value of around 500 at a black liquor solids of around 60% at 95 Deg C thereby restricting the firing of black liquor at comparatively lower black liquor solids ( around 60%) resulting in comparatively lower energy efficiency in the chemical recovery system.

We Claim:
1. An apparatus for treating raw material comprising:
(e) a feeder assembly for receiving and feeding the raw material to be treated;
(f) a milling system [E] having a treatment chamber to which the raw material is fed, comprising a pair of optimally designed discs [edr, eds] having adjustable space in between, wherein one of the disk is stator [eds] and the other is rotary [edr];
(g) an impeller [id] attached to the rotary disk [edr]:
(h) a separating/sieving system [G] comprising a universal separator, an inlet to the separator and the brush auger assembly having optimized openings spaced at equal distance for sifting the treated raw material.
2. The apparatus as claimed in claim 1, wherein the raw material is selected from the group comprising straws, bagasse, grass, cotton linters. cotton rags, linen, hemp, manila and other agro based fibrous material.
3. The apparatus as claimed in claim 1 or 2. wherein said feeder assembly comprises: (i) one or more hoppers [A] for receiving the raw material,
(ii) a conveying system [B.C] for transporting the raw material from the receiving hopper
[A] to the feeder hopper [D]; (iii) feeder hopper [D] for feeding the raw material to the milling system [E].
4. The apparatus as claimed in any preceding claim, wherein the said milling system [E] is a disk mill comprising the said treatment chamber which is an assembly of disks [eds, edr], grinding/treatment elements, a gap adjustment mechanical system, a shaft, an impeller [id], all connected to each other and said assembly mounted such as hereinbefore described in a casing, wherein said casing is preferably a welded steel profile frame.
5. The apparatus as claimed in any preceding claim, wherein said rotary [edr] and stator [eds] discs of said milling system [E] comprises optimally designed grinding/treatment elements [ede(II)] attached on the periphery of the said discs [eds, edr] by attaching means at an specified angle [a°].

6. The apparatus as claimed in any preceding claim, wherein said rotary [edr] and stator [eds] discs of said milling system [E] are preferably vertically mounted in said treatment chamber, preferably inside a housing that can be opened as and when required for cleaning and servicing purposes.
7. The apparatus as claimed in claim 5. wherein said attaching means are two screws per grinding/treatment element [ede(ll)] having specified internal diameter [edei] and external diameter [edeo]. and are placed at an appropriate distance so as to properly fix the grinding/treatment element [ede(II)] to the discs [eds, edr].
8. The apparatus as claimed in any preceding claim, wherein said grinding/treatment elements [ede(II)] have an optimized design of alternating teeth and groves forming a pattern of ridges, wherein the teeth are tooled off to obtain a flattened surface, providing a brushing action therefor.
9. The apparatus as claimed in any preceding claim, wherein said teeth and groves of said grinding/treatment elements [ede(II)] are either parallel to the left edge or to the right edge of the element at specified angle [edela°].
10. The apparatus as claimed in any preceding claim, wherein said grinding/treatment elements [ede II] are [edel] in width at the top and [ede3] wide at the bottom.
11. The apparatus as claimed in any preceding claim, wherein distance between two successive edges on each grinding/treatment element [edell] is [ede4], distance between two successive edges on each grinding/treatment element at the top edge is [ede5], depth of the groves in said elements is [ede8] and angle between two successive groves is [edeta] degrees.
12. The apparatus as claimed in any preceding claim, wherein said stator disk [eds] has a central circular hole [eds5].
13. The apparatus as claimed in any preceding claim, wherein said rotary disk [edr] is mounted on a shaft, wherein further the said shaft is mounted in a cast iron housing supported by double ball bearing inserted in the space [edr 17] of the rotary disk [edr].

14. The apparatus as claimed in any preceding claim, wherein an impeller [id] is connected with the base of the said shaft.
15. The apparatus as claimed in any preceding claim, wherein the said impeller [id] having a diameter [id5] to fit on the rotor, curved veins at an angle of [b] degrees, each curved blades [id2] long and [idl] wide, wherein the curvature of the impeller blades is at an radial angle of (rdl°).
16. The apparatus as claimed in any preceding claim, wherein the said separating system [G] receives the sift able bagasse into the said universal separator consisting of a brush auger and sieves which separates the pith from the fibrous portion of the bagasse.
17. The apparatus as claimed in any preceding claim, wherein the said separating system [G] is [gl] in height and [g2] in breadth, the outer casing of the auger brush is [g7] in diameter, the auger brush is [g7] in diameter and wherein the said brush is propelled by a motor.
18. The apparatus as claimed in any preceding claim, wherein separated pith and fibrous material falls though the sieves by gravity and is collected separately with the help of hoppers at the bottom of the said separating system [G].
19. A method for the treatment of raw/waste material to obtain a sift able biomass wherein the pith and undesirable biomass can be effectively separated from the raw/waste material comprising:
receiving the raw material in a receiving hopper with adjustable opening(s);
conveying raw material from hopper opening to preferably by a conveyer;
optionally subjecting the raw material to magnetic separation by positioning magnetic
separation above the moving conveyer to remove any metallic parts/impurities;
supplying the raw material to a feeder hopper under the influence of gravity;
feeding the raw material from feeder hopper into disc gap of the treatment chamber of the
disk mill with the help of a specially designed impeller connected with the base of the shaft;
regulating the rate at which raw material is fed as per the need/nature of the raw material;

the proper entry space of the raw material is maintained with the help of a gap adjustment
mechanical system for giving maximum defiberization and is varied with respect to the
quality, type and moisture content of the raw material being used for depithing;
imparting maximum brushing action and minimum cutting action to the raw material to
dislodge maximum pith;
collecting the treated sift able substrate under the influence of gravity;
subjecting the collected treated sift able substrate to separation in the separating system;
separating the outlet treated sift able substrate into the separated fractions.
20. The method as claimed in claim 19, wherein the raw material is selected from the group comprising straws, bagasse, grass, cotton linters. cotton rags, linen, hemp, manila and other agro based fibrous material.
21. The method as claimed in claims 19 and 20, wherein the said raw material is bagasse and the said separated fractions comprises of three fraction, wherein the first fraction is pith, the second is the short fiber and the third fraction is made up of the long fibers.