AU2003290423B2 - An integrated small-scale pulse mill - Google Patents

Description

WO 2005/063397 PCT/IN2003/000438 1 AN INTEGRATED SMALL-SCALE PULSE MILL FIELD OF THE INVENTION: The present invention relates to development of an integrated small-scale pulse mill which dehusks pulses and separates husk, powder and dehulled pulses in a compact integrated 5 unit. BACKGROUND AND PRIOR ART DESCRIPTION: India is one of the major producers of pulses in the world contributing about 25% of the total production. Apart from common pulses like Bengal gram, tur (red gram), green gram and black gram, a good number of other pulses such as cowpea, kidney beans, horse grain, 10 lentil, moth bean etc. are also produced and consumed in different regions of the country. The annual production of pulses is about 15 million tones and generally they are consumed in a variety of food products after conversion into dhal i.e. dehusked and split pulse. Conversion of pulses to dhal is tie third largest food processing industry after rice and wheat. It is estimated that more than 75% of the pulses produced are converted into 15 dhal. The operation of milling pulses consists of two major steps: 1. Loosening of the husk from cotyledons. 2. Removal of husk followed by splitting into two cotyledons. The first step of loosening of husk is achieved by suitable pre-milling' treatments (either wet or dry method) while its removal (second step) is done using contrivances/machines 20 like chakki, under - runner disc Sheller, cone polisher, emery roller etc. depending on the scale of operation and the type of pulse. Dhal milling is being practiced in India since centuries. Traditionally pulses are either soaked in water for some period, and then sun-dried (wet method) or given a 'pitting' oiling - watering - sun - drying treatment (dry method) prior to milling. These operations 25 were carried out in rural areas in home or cottage scale in earlier days. The loosened husk was removed using chakki, dhenki or pestle and mortar. With the advent of the technology, the premilling treatments (dry method) and subsequent milling of pulses were carried out in large scale using emery rollers, under runner disk shellers or similar machines. 30 Large scale dhal milling industries need huge capital investment, power and raw material to gain economic viability while small scale or tiny scale units produce inferior quality product with lesser yield compared to large scale dhal mills. With the establishment of large scale dhal mills the village level processing units are almost extinct since -they were not able to compete with large scale dhal mills in tens of yield and quality of dhal.

-2 In order to revive this village level pulse processing industry CFTRI has earlier developed hand-operated pulse dehusker and mini dhal mill to replace wasteful chakki, dhenki, or pestle and mortar. The teams of inventors of these machines are Dr. P. P. Kurian, Mr. N. Ramakrishnaiah, Mr. V. M. Pratape and Mr. B. S. Patil. These units 5 work on abrasion principle and essentially consist of an emery coated cone rotating inside a wire mesh cage. The angle of the emery cone of hand-operated unit is 45 while that of mini dhal mill is 60 . These units can process 50-100 Kgs of conditioned pulse per hour. Although these units are popular with village level processors they have got their own 10 limitations. One of the major draw back is that they can process only wet preconditioned pulse and are suitable for processing of bolder grains like tur, Bengal gram and peas only. A survey conducted earlier has revealed that there has been a persistent demand from dhal processors to improve the traditional roller machine or develop an intermediate/medium capacity dhal mill/dehusking unit which will dehusk 15 almost all pulses efficiently and will be economically suitable for small scale dhal processors. The present machines either give excessive scouring leading to both qualitative and quantitative loss or do not give fully dehusked product, which leads to poor market value of the product. There is an urgent need to improve upon the existing machines or develop a new one, which gives fully dehusked product with least powder 20 loss. The premilling treatment to be given to the pulses should also be easily adaptable and not very specific or critical. An improved mechanized pulse dehusker has been invented by the same inventors (N. Ramakrishnaiah, H. V. Narasimha, V. M. Pratape) which is covered under Indian Patent Application No. 2385/DEL/98 (currently pending). Although the dehusker can dehull 25 all kinds of preconditioned pulses, the limitation was, the aspiration of husk, powder and brokens and separation of dhal has not taken care off. SUMMARY OF THE INVENTION: The present invention provides an integrated small-scale pulse mill for milling different 30 types of pulses, said mill comprising: a feed hopper (A) provided with a control mechanism being fitted atop a top side of a milling chamber (B) for controllably feeding the pulses to the milling chamber, wherein said milling chamber dehulls the pulses and produces a mill stream consisting of milled product of dehulled grains/dhal, husk and powder; 35 said milling chamber comprising a truncated cone rotating inside a woven wire mesh screen cage; 2526570_1 (GHMatters) 7/01/11 -3 a chute (C) being provided at a bottom side of the milling chamber for removing the mill stream from the milling chamber and feeding the same to an aspiration system (G); said aspiration system comprising an expansion chamber; said expansion chamber being coupled to 5 a centrifugal blower (H) which is driven by motor (F) for delivering air at a predetermined air flow rate and pressure for sucking husk and powder off the milled product a dust collector for collecting the separated powder and husk by the centrifugal blower (H) from the mill stream; 10 the milled product fall under gravity from said expansion chamber on a reciprocating sieve deck through a shaft for separating the husk from the whole dehulled grains; said sieve is being vibrated/reciprocated by the motor (F); said milling chamber, aspirating chamber, shaft and the sieve being coupled to a driving mechanism, and the whole mill being mounted securely on a sturdy frame structure. 15 BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWING: In the drawing accompany the specification Figure I represents the schematic diagram of the integrated pulse milling system of the present invention. 20 Figure 2 represents the flow chart for processing of pulses by dry method. Figure 3 represents the flow chart for processing of pulses by wet method. DETAILED DESCRIPTION OF THE PRESENT INVENTION: Accordingly, the present invention provides an integrated small-scale pulse mill for 25 milling different types of pulses, said mill comprising: a feed hopper (A) provided with a control mechanism being fitted atop a top side of a milling chamber (B) for controllably feeding the pulses to the milling chamber, wherein said milling chamber dehulls the pulses and produces a mill stream consisting of whole dehulled grains/dhal, husk and powder; 30 said milling chamber comprising of a truncated cone rotating inside a woven wire mesh cage; a chute (C) being provided at a bottom side of the milling chamber for removing the mill stream from the milling chamber and feeding the same to an aspiration system (G) comprising of an expansion chamber; said expansion chamber being coupled to a centrifugal blower (H) for delivering air at a 2526570 1 (GHMatters) 7/01/11 -3A predetermined air flow rate and pressure and a dust collector for separating the powder from the mill stream; said aspiration chamber being coupled to a sieve through a shaft for separating the husk from the whole dehulled grains; 5 said milling chamber, aspirating chamber, shaft and the sieve being coupled to a driving mechanism, and the whole mill being mounted securely on a sturdy frame structure. In an embodiment of the present invention, the control mechanism is a mechanical control mechanism or a electrical control mechanism or a pneumatic control mechanism. 10 In another embodiment of the present invention, the milling chamber consists of a top and a bottom open truncated cone shaped wire mesh cage having inside it a concentrically placed rotatable abrasive coated cone having a base angle in the range of 45 to 85 , the said coated cone being fixed atop a vertical. shaft being rotatably fixed onto a support structure by fixing means and coupled to a prime mover. 2526570 1 (GHMatters) 7/01/11 WO 2005/063397 PCT/IN2003/000438 4 In yet another embodiment of the present invention, the milling chamber consists of a truncated cone, coated with emery or carborundum or resinoid material with particle size of Aluminium oxide or silicon carbide or both of mesh size in the range of 8 to 40 BSS mesh. 5 In still another embodiment of the present invention, the base angle is greater than 600. In one more embodiment of the present invention, the truncated cones are cast on a fabricated MS or Cl conical base and are provided with provision to mount the said cone on a shaft. In one another embodiment of the present invention, the diameter of the shaft is in the 10 range of 25 to 75 mm. In a further embodiment of the present invention, the truncated cones are mounted vertically on the shaft such that they allow gravity-assisted flow of milling stream. In a further more embodiment of the present invention, the diameter of the truncated cone is the range of 100mm to 300mm at the top and 350mm to 450mm at the bottom; with a 15 curved surface area of 1500 to 3000 cm 2 . In an embodiment of the present invention, the said cone is fixed to the vertical shaft and rotates inside a spring steel or any other suitable woven wire mesh screen cage of 8 to 24 BSS mesh concentric to the said cone, to get the desired dehusking capacity in the range of 75 to 100 kg h 1 20 In another embodiment of the present invention, the' clearance between the cone and wire mesh screen is adjustable vertically, to attain a clearance of 2mm to 20mm to suit different types and sizes of pulses being milled. In yet another embodiment of the present invention, the peripheral speed of the said cone is in the range of 500 to 1500 m/min for efficient dehusking of different variety of pulses 25 such as Tur, Bengal gram, Green gram, Black gram, Horse gram, Lentil, amongst others. In still another embodiment of the present invention, the aspiration chamber is designed to suit the capacity of 80 to 100 kg of mill stream products per hour with the centrifugal blower (or any other similar contrivance) running at 2000 to 4000 rpm delivering suitable air pressure of at a volume flow rate of 200 - 400 ft 3 min- for aspiration of 10 to 25 kg of 30 light material per hour. In one more embodiment of the present invention, the dust collection system consists of an inlet and an outlet ducting connected to the Cyclone collector or any such similar device for collecting the said aspirated light material.

WO 2005/063397 PCT/IN2003/000438 5 In one another embodiment of the present invention, the milled products fall by gravity or any similar means on to a reciprocating sieve deck driven through an eccentric of 10 to 30 mm eccentricity or driven by a vibratory motor or any other similar such device with sieves having round and oblong openings ranging from 2mm to 5mm for separating 5 brokens, dhal and whole grains of different pulses so milled, with the sieves being interchangeable to accommodate different sizes of brokens, dhal and grains. In a further embodiment of the present invention, the entire system described above is mounted on a single or multiple sturdy frame(s) constructed out of mild steel angles, flats, channels, pipes (square, round or rectangular) or similar such material(s). 10 As can be seen from the figure 1, which represents the schematic diagram of the improved milling system, the milling system consists of the following parts: A - Feed hopper B - Dehusker as covered under patent C - Chute for discharging millstream 15 D - Pulley, which can be moved up or down to adjust dehulling of different pulses E - Motor for driving the milling system F - Motor for driving aspiration and separation system G - Aspiration chamber to suck husk and powder H - Blower, which sucks Husk and powder 20 I - Sieving to separate dhal, brokens and whole grain J - Dust collector The integrated small scale pulse mill which mainly consists of an improved mechanized pulse dehusker (covered under patent application No. 2385/DEL/98), aspiration and collection of husk and powder and separation of dhal, brokens and whole grain all in a 25 compact integrated unit. The conditioned pulses are fed in hopper A - which are dehulled in the dehusker B - The mill stream consisting of whole dehulled grain, dhal, husk and powder comes through chute C - and fed to the aspiration chamber G - The blower H sucks off the husk and powder and it is collected in dust collector J - The cleaned mill stream is separated in sieving unit I - into dhal, brokens and whole grains. The milling 30 system shown in Fig. 1 is driven by motor E while the aspiration and sieving system is run by another separate motor F. The flow chart for processing pulses in the integrated small-scale pulse mill is given and the said pulse mill is having a capacity of 80 - 100 kg pulses per hour.

WO 2005/063397 PCT/IN2003/000438 6 The performance of the pulse mill is tested by milling different varieties of all major pulses (tur, Bengal, green gram, and black gram) as well as minor pulses. The following examples are given by way of illustrations of present invent and should not be constructed to limit the scope of the present invention. 5 EXAMPLE 1: A commercial variety of tur pulse procured from the local market was processed to dhal using this dehusker (3 batches of 50 kg each). First the material was cleaned and graded using a pre-cleaner / grader consisting as suitable sieves. The major fraction of material was given a pretreatment generally followed by dhal millers i.e. scarification of husk, 10 oiling, sun - drying, watering and sun - drying again. The material was milled in the dehusker at peripheral speed of 800 mts / min. The millstream was fed to system when yield of dhal obtained was 78% (on cleaned and graded materials basis) with 99% dehusking, brokens - 3% and Husk & powder - 16%. EXAMPLE 2: 15 A local variety of Bengal gram was given wet premilling treatment consisting of soaking in water for 45 min, draining the water, keeping over night after spreading and sun drying for 2 days. 50 Kgs batches -3 Nos. were processed to dhal using this mill, the yield of dhal obtained was 79% (cleaned, graded raw material basis) with 99.5% dehusking, brokens 2%, Husk and powder - 17%. 20 EXAMPLE 3: Locally available variety of black gram was cleaned, graded, in pre-cleaner cum grader and given the traditional pretreatment consisting of scarification of husk, oiling, sun - drying, watering and sun - drying again. The material when milled in the pulse mill has given a dhal yield of 77% with 99.5% dehusking. While broken were 5% and Husk / powder 16% 25 EXAMPLE 4: 3 batches (50 Kgs each) of clean Green gram were given a pretreatment consisting of scarification of husk, oiling, holding overnight, sun-drying, watering and sun-drying. When pretreated material is milled in the mill, a dhal yield of 76% with 99.5% dehusking is obtained. While brokens were 6% and husk and powder - 16%. 30 EXAMPLE 5: 50 kg Lentil was'processed to dhal after pre-treatment (moistening and sun drying) when a dhal yield of 80% has obtained. (Brokens - 2%, Husk & powder -16%) The novelty of this unit is that the dehulling, aspiration and separation system are combined in 1 unit which gives significantly higher yield (76 - 79%) of dhal at reasonably 7 lower power consumption (2 HP). The unit are the integrated mill can process almost all types of pulses to dhal irrespective of pre-milling treatment. The main advantages of the present invention are: 1. It can process all types and sizes of pulses. Even smaller quantities (e. g. 100 gm) 5 could be milled while the traditional machines of similar capacity need at least 5 kg material. 2. Gives 2-4% higher yield of clean dhal than the traditional machines. 3. Gives 98-99.5% dehusked dhal (market requirement-minimum 97%). 4. Suitable for milling of both dry and wet pre-conditioned pulse in rural sector. 10 In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the 15 presence or addition of further features in various embodiments of the invention. It is to be understood that, if any prior art publication is referred to herein, such reference does not constitute an admission that the publication forms a part of the common general knowledge in the art, in Australia or any other country. 2526570_ 1 (GHMatters) 7/01/11

Claims (17)

1. An integrated small-scale pulse mill for milling different types of pulses, said mill comprising: a feed hopper (A) provided with a control mechanism being fitted atop a top side of a 5 milling chamber (B) for controllably feeding the pulses to the milling chamber, wherein said milling chamber dehulls the pulses and produces a mill stream consisting of milled product of dehulled grains/dhal, husk and powder; said milling chamber comprising a truncated cone rotating inside a woven wire mesh screen cage; 10 a chute (C) being provided at a bottom side of the milling chamber for removing the mill stream from the milling chamber and feeding the same to an aspiration system (G); said aspiration system comprising an expansion chamber; said expansion chamber being coupled to a centrifugal blower (H) which is driven by motor (F) for delivering air at a 15 predetermined air flow rate and pressure for sucking husk and powder off the milled product a dust collector for collecting the separated powder and husk by the centrifugal blower (H) from the mill stream; the milled product fall under gravity from said expansion chamber on a reciprocating 20 sieve deck through a shaft for separating the husk from the whole dehulled grains; said sieve is being vibrated/reciprocated by the motor (F); said milling chamber, aspirating chamber, shaft and the sieve being coupled to a driving mechanism, and the whole mill being mounted securely on a sturdy frame structure. 25

2. An integrated small-scale pulse mill as claimed in claim 1, wherein the control mechanism is a mechanical control mechanism, electrical control mechanism or a pneumatic control mechanism.

3. An integrated small-scale pulse mill as claimed in claim 1, wherein the milling 30 chamber consists of a top and a bottom open truncated cone shaped wire mesh cage having inside it a concentrically placed rotatable abrasive coated cone having a base 252657 1 (GHatters) 7/01/11 9 angle in the range of 45* to 850, the said coated cone being fixed atop a vertical shaft being rotatably fixed onto a support structure by fixing means and coupled to a prime mover. 5

4. An integrated small-scale pulse mill as claimed in claim 3, wherein the milling chamber consists of a truncated cone, coated with emery or carborundum or resinoid material with particle size of Aluminium oxide or silicon carbide or both of mesh size in the range of 8 to 40 BSS mesh.

5. An integrated small-scale pulse mill as claimed in claim 3, wherein the base angle 10 greater than 60'.

6. An integrated small-scale pulse mill as claimed in claim 3, wherein the trmcated cones are cast on a fabricated MS or Cl conical base and are provided with provision to mount the said cone on a shaft. 15

7. An integrated small-scale pulse mill as claimed in claim 6, wherein the diameter of the shaft is in the range of 25 to 75 mm.

8. An integrated small-scale pulse mill as claimed in claim 3, wherein the truncated 20 cones are mounted vertically on the shaft such that they allow gravity assisted flow of material.

9. An integrated small-scale pulse mill as claimed in claim 1, wherein the diameter of the truncated cone is the range of 100mm to 300mm at the top and 350mm to 450mm at 25 the bottom; with a curved surface area of 1500 to 3000 cm 2

10. An integrated small-scale pulse mill as claimed in claim 1, wherein the said cone is fixed to the vertical shaft and rotates inside a spring steel or woven wire mesh screen cage of 8 to 24 BSS mesh concentric to the said cone, to get the dehusking capacity in 30 the range of 75 to 100 kg/h. 2526570 1 (GHMatters) 7/01/11 10

11. An integrated small-scale pulse mill as claimed in claim 1, wherein the clearance between the cone and wire mesh screen is vertically adjustable, to attain a clearance of 2mm to 20mm. 5

12. An integrated small-scale pulse mill as claimed in claim 1, wherein the peripheral speed of the said cone is in the range of 500 to 1500 m min-' for dehusking different variety of pulses such as Tur, Bengal gram, Green gram, Black gram, Horse gram and Lentil.

13. An integrated small-scale pulse mill as claimed in claim 1, wherein the aspiration 10 chamber is designed to suit a capacity of 80 to 100 kg of mill stream products per hour with the centrifugal blower running at 2000 to 4000 rpm delivering air pressure of at a volume flow rate of 200-400 ft 3 min~ 1 for aspiration of 10 to 25 kg of light material per hour. 15

14. An integrated small-scale pulse mill as claimed in claim 1, wherein the dust collection system consists of an inlet and an outlet ducting connected to a cyclone collector for collecting the said aspirated light material.

15. An integrated small-scale pulse mill as claimed in claim 1, wherein the milled 20 product fall under gravity on to a reciprocating sieve deck driven through an eccentric of 10 to 30 mm eccentricity or driven by a vibratory motor with sieves having round and oblong openings ranging from 2mm to 5mm for separation of brokens, dhal and whole grains of different pulses so milled, with the sieves being interchangeable to accommodate different sizes of brokens, dhal and grains. 25

16. An integrated small-scale pulse mill as claimed in claim 1, wherein the entire system described above is mounted on a single or multiple sturdy frame(s) constructed out of mild steel angles, flats, channels, pipes that are square, round or rectangular. 30

17. An integrated small-scale pulse mill substantially as herein described with reference to the accompanying drawings. 2526570_1 (GHMatters) 2/01/11