Title of Invention

A PROCESS FOR THE PREPARATION OF PESTICIDAL ALUMINIUM PHOSPHIDE AND A VERTICAL REACTOR FOR CARRYING OUT THE PROCESS

Abstract

A process for the preparation of pesticidal aluminium phosphide in which the reaction of aluminium powder and yellow phosphorous is carried out in the presence of graphite powder under controlled induction heating and continuous agitation of the reaction mixture. Also a vertical reactor (1) for carrying out the process comprising a container (2) fitted vapour tight with a detachable lid (3) provided with a vent nozzle (9) connected to a water seal (10) and further provided with a pair of oppositely disposed windows (13). An agitator (15) is provided in the container whose shaft (16) is coupled to the shaft (22) of a geared motor (20). A product poker arrangement (37) and a phosphorous feed cum poker means (45) are provided at the bottom of the reactor. The reactor includes an induction heating arrangement (54) connected to an AC power supply (57) through a control panel (58) and a main switch (59) and also to a water demineralising, cooling and recirculating arrangement (60). A temperature probe (61) is provided at the bottom of the reactor (Figl).

Full Text

FORM 2 THE PATENTS ACT 1970 As amended by the Patents (Amendment) Act, 2002 COMPLETE SPECIFICATION (See Section 10; Rule 13) TITLE A process for the preparation of pesticidal aluminium phosphide and a vertical reactor for carrying out the process APPLICANTS Excel Crop Care Limited, 184-87, Swami Vivekanand Road, Jogeshwari, Mumbai 400 102, Maharashtra, India, an Indian Company INVENTORS Shroff Dipesh Kantisen, Jain Ash ok Kundanmal, Pandya Yogendra Hariharbhai, Auti Avinash Shivaji and Chavan Ashutosh Mukund, all Indian Nationals and all of Excel Crop Care Limited, 184-87, Swami Vivekanand Road, Jogeshwari, Mumbai 400 102, Maharashtra, India The following specification particularly describes the nature of this invention and the manner in which it is to be performed : FIELD OF INVENTION This invention relates to a process for the preparation of pesticidal aluminium phosphide and a vertical reactor for carrying out the process. Aluminium phosphide is used to generate phosphine gas which is a well known and very effective pesticide. PRIOR ART British Patent No 1057035 relates to a method for the preparation of aluminium phosphide by disproportionation of unstable volatile aluminium halide in the presence of excess phosphorus in the vapour phase into stable aluminium halide and finely divided aluminium. Stable aluminium halide vapours are passed over molten aluminium to form the unstable volatile aluminium halide. Typically the reaction temperatures are 1150- 1160 ° C. This is a two step method which is time consuming and cumbersome to carry out. It also consumes considerable energy and is very expensive. A furnace assembly comprising a horizontal tube reactor is employed to carry out the method. US Patent No 4331642 describes a process for the preparation of aluminium phosphide by reacting aluminium powder and yellow phosphorus at 300 to 600°C in an inert atmosphere and in the presence of a catalyst such as chlorine, bromine or iodine. It employs a reactOT comprising a "vessel closed by a water seal. Aluminium powder and iodine catalyst are first heated in the reactor followed by addition of yellow phosphorous after shutting off heating (Example 9). The reactor is presumed to be heated by a gas furnace from outside the bottom thereof. The reaction mixture is in direct contact with the reactor. The reaction mixture in the non-stirring zone between the reactor bottom surface and the bottom blades of the stirrer experiences the maximum heat. Therefore, there is a possibility of the aluminium particles getting overheated and melting thereby causing agglomeration of the reaction mass. Due to agglomeration heat availability to the inner layers of the reaction mass is reduced gradually considerably. This results in uneven heat transfer to and non-uniform heating of the reaction mixture thereby leading to wastage of heat and reactants. On introduction of yellow phosphorous into the reactor due to the exothermic nature of the reaction, there may be spot temperature increase. This may also lead to overheating and melting of the aluminium particles and agglomeration. Thus yield and process efficiency are reduced and the process is rendered expensive. US Patent No 4412979 teaches that if the aluminium powder and yellow phosphorus are slowly added into a reactor, safety and controllability of the process are improved. It employs a reactor comprising a cylindrical container provided with a stirrer, a cooling system, temperature probes, inert gas inlet line and waste gas outlet line. The container is also provided with a supply vessel for liquid phosphorous having a pump and a supply vessel for the aluminium powder having a conveying device. The discharge opening at the bottom of the reactor is provided with a locking off device. The reactor is further provided with a rupture disc in the waste gas outlet line to counter any possible increase in pressure. The waste gas is led off over a water receiver having a glass fiber filter and a postconnected activated carbon filter. The bottom of the reactor is heatable by a gas burner from the outside to the reaction temperature (Example 4). This patent uses a certain amount of aluminium phosphide from an earlier charge in the reactor prior to starting a new charge. Due to the aluminium phosphide being highly reactive with water there is the possibility of formation of phosphine and hydroxide which may get converted into oxide and water at the high reaction temperature. This is highly undesirable in that the water reacts with aluminium phosphide and builds up pressure leading to safety problems. Also there is the possibility of the aluminium phosphide at the bottom of the reactor hampering the heat transfer to the reaction mixture thereby resulting in wastage of heat and underutilization of the reactants. Additionally there is possibility of spot temperature increase in the reactor at the time of introduction of yellow phosphorous leading to overheating and melting of the aluminium particles and resultant agglomeration of the reaction mass. This in turn reduces the yield and process efficiency and renders the process expensive. OBJECTS OF INVENTION An object of the invention is to provide a process for the preparation of pesticidal aluminium phosphide, which ensures substantially uniform heating of the reaction mixture to prevent agglomeration of the reaction mass and wastage of heat and to improve yield and process efficiency. Another object of the invention is to provide a process for the preparation of pesticidal aluminium phosphide, which produces substantially free flowing aluminium phosphide whose discharge is smooth. Another object of the invention is to provide a process for the preparation of pesticidal aluminium phosphide, which is safe and economical. Another object of the invention is to provide a process for the preparation of pesticidal aluminium phosphide, which produces aluminium phosphide in admixture with graphite powder. Another object of the invention is to provide a reactor for carrying out the process preparation of pesticidal aluminium phosphide, which ensures substantially uniform heating of the reaction mixture to prevent agglomeration of the reaction mass and wastage of heat and to improve yield and process efficiency. Another object of the invention is to provide a reactor for carrying out process of preparation of pesticidal aluminium phosphide, which produces substantially free flowing aluminium phosphide whose discharge is smooth. Another object of the invention is to provide a reactor for carrying out process of preparation of pesticidal aluminium phosphide, which eliminates the excess pressure relieving rupture disc and is safe and produces pesticidal aluminium phosphide economically. Another object of the invention is to provide a reactor for carrying out process of preparation of pesticidal aluminium phosphide, which produces aluminium phosphide in admixture with graphite powder. DESCRIPTION OF INVENTION According to the invention there is provided a process for the preparation of pesticidal aluminium phosphide comprising reacting aluminium powder and yellow phosphorous at 300 to 650 ° C in an inert atmosphere and in the presence of a catalyst, wherein the reaction is carried out in the presence of graphite powder under controlled induction heating and continuous agitation of the reaction mixture. According to me 'invention there is also provided pest'ic'idal aluminium phosphide in combination with graphite powder obtained by the process described above. According to the invention there is also provided a vertical reactor for carrying out the process of preparation of pesticidal aluminium phosphide described above comprising a container made of a corrosion resistant thermal conductor material and fitted vapour tight with a detachable lid provided with a vent nozzle connected to a water seal through a vent line having an inert gas inlet and further provided with a pair of oppositely disposed windows with closures, an agitator provided in the container and comprising a plurality of blades fitted to the agitator shaft which is coupled to the shaft of a geared motor mounted on the lid gas tight with the container, a detachable plug for the discharge opening of the reactor, a product poker arrangement provided at the bottom of the reactor, phosphorous feed cum poker means provided at the water cooled hollow induction coil wound around the lower part of the container over insulating material, the coil being connected to an AC power supply through a control panel and a main switch and also to a water demineralising, cooling and recirculating arrangement and a temperature probe provided at the bottom of the reactor. Fig 1 is schematic front view of a vertical reactor according to an embodiment of the invention; Fig 2 is enlarged view at X in Fig 1; Fig 3 is top view of the lid of the reactor of Fig 1; Fig 4 is front view of the lid of the reactor of Fig 3; Fig 5 is front view of the agitator of the reactor of Fig 1; Fig 6 is top view of the agitator of Fig 5; Fig 7 is isometric view of the agitator of Fig 5; Fig 8 is scrap view of bottom portion of the reactor of Fig 1 around the discharge opening of the reactor; Fig 9 is exploded view of the bottom portion of Fig 8; Fig 10 is top view of the detachable plug in Fig 9; Fig 11 is enlarged view of the product poker and phosphorus feed cum poker arrangements of the reactor of Fig 1 in their operational positions; and Fig 12 is enlarged view of the product poker and phosphorous feed cum poker arrangements of the reactor of Fig 1 in their non-operational positions. As illustrated in Figs 1 to 12 of the accompanying drawings, 1 is a vertical reactor comprising a container 2 provided with a flange 2a at the mouth thereof and made of a corrosion resistant thermal conductor material such as mild steel (Figs \ and 2). The containei is cylindrical with a tori spherical bottom. 3 is a lid detachably fitted to the container vapour tight against a gasket 3a by J- clamps 4 by tightening nuts 5 on bolts 6 pivoted (pivot marked 7) on lugs 8 at the outer surface of the container, against the J-clamps (Figs 1 and 2). The J-clamps move down and press the lid against the flange 2a at the container mouth. The gasket 3 a sits in an annular groove 2b in the flange 2a. The lid is detachable from the container by loosening the nuts 5 on bolts 6 from the J-clamps and moving out the J-clamps about their pivots. The lid is provided with a vent nozzle 9 connected to a water seal 10 through a vent line 11 having an inert gas inlet 12. 12a is flange for connecting the vent line to an inert gas source (not shown). The vent noozle is provided with a flange 9a which is fitted to a flange 11a provided at one end of the vent line by bolts 1 lb. Besides bolts other known means such as screws also may be used to fit the flanges 9a and 11a together. Bolt fit between the vent nozzle and vent line makes assembly and disassembly of the vent line to and from the lid easy. The lid is further provided with a pair of oppositely disposed windows 13 with closures 14 fitted to the lid with bolts 14a (Figs 3 and 4). Preferably, the windows and the respective closures are arc-shaped. Besides bolts, other known means such as screws also may be used to fit the closures to the windows. 15 is an agitator provided in the container and comprising two sets of blades 17a, 17b, and 17c and 18a, 18b and 18c disposed one below the other with respect to the agitator shaft 16 (Figs 5, 6 and 7). The upper blades 17a, 17b and 17c are arranged equidistantly in the vertical plane. The lower blades 18a, 18b and 18c are also arranged equidistantly in the vertical plane but offset with the upper blades (Fig 6). Both the sets of blades are fitted to the agitator shaft at an angle of 5 - 50 ° with the axis of the agitator shaft. The agitator also comprises two blades 19a and 19b disposed oppositely at the bottom of the agitator shaft defining a clearance between 4 to 10 mm with the container bottom and fitted to the agitator shaft at an angle of 5-50° with the axis of the agitator shaft. The blades 19a and 19b at the bottom of the agitator shaft are curved corresponding to the spherical container bottom. Preferably, the blades are fitted to the agitator shaft at an angle of 45 ° with the axis of the agitator shaft. Preferably, the blades at the bottom of the agitator shaft define a clearance of 5 mm with the container bottom. 20 is a geared motor mounted on a platform 21 which in turn is mounted on the lid (Fig 1). The shaft 22 of the geared motor is two piece construction comprising shaft members 22a and 22b coupled together with a coupler 23. Shaft member 22b of the geared motor extends into the container through a gas tight seal 24 located within the platform and through shaft hole 22c in the lid and is coupled to the shaft of the agitator by a coupler 25 (Figs 1 and 3). Since the geared motor shaft is of two piece construction and the second shaft member is coupled to the agitator shaft, the agitator may be replaced or repaired easily by simply opening the lid without dismantling the entire geared motor. 26 is a detachable plug for the discharge opening 27 of the reactor (Fig 9). The detachable plug is inverted Tee in cross section. The vertical limb 28 of the plug is adapted to fit into the discharge opening and the horizontal limb 29 of the plug is adapted to overlap the discharge opening and register with a rim 30 at the outer surface of the bottom of the discharge opening. The horizontal limb is provided with handles 31 and is further provided with oppositely disposed open slots 32 at the periphery thereof (Fig 10). The plug is detachably fitted to the bottom of the reactor against a gasket 33 by engaging bolts 34 pivoted (pivots marked 35) at the bottom of the reactor in the corresponding open slots in the horizontal limb and tightening wing nuts 36 provided at the distal ends of the bolts against the bottom of the horizontal limb (Figs 8, 9 and 10). The plug is detachable from the bottom of the reactor by loosening the wing nuts 36 from the horizontal limb and disengaging the bolts 34 from the open slots by moving out the bolts about their pivots. 37 is a product poker arrangement comprising a tubular member 38 fitted at the bottom of the reactor and opening into the reactor. The tubular member is of three piece construction comprising three members 38a, 38b and 38c whose respective flanges 38a', 38b' and 38b" and 38c" are fitted together gas tight against gaskets 38e by bolts 38d (Figs 1,11 and 12). The three piece construction of the tubular member makes its assembly and disassembly easy and convenient. 39 is a poker rod reciprocatably held in the tubular member through a gas tight seal 40 located in the tubular member. The tip 41 of the poker rod is extendable into the reactor bottom (Fig 11). The outer end of the poker rod is provided with a handle 42. The poker rod is also provided with a locking pin 43 engagable in a lateral hole 44 provided through the poker rod at an intermediate reaction thereof and is adapted to abut the outer end of the tubular member in the locked position of the poker rod (Fig 12). 45 is a phosphorous feed cum poker means comprising a sleeve 46 provided with a phosphorous feeder spout 47 projecting from its side. The sleeve is fitted to and opens into the tubular member. The sleeve is of two piece construction comprising two members 46a and 46b whose respective flanges 46a' and 46b' are fitted together gas tight against gasket 46c by bolts 46d. The two piece construction of the sleeve makes its assembly and disassembly easy and convenient. A poker rod member 48 is reciprocatably held in the sleeve through a gas tight seal 49 located in the sleeve. The tip 50 of the poker rod member is extendable into the tubular member (Fig 11). The outer end of the poker rod member is provided with a handle 51. The poker rod member is also provided with a locking pin 52 engagable in a lateral hole 53 provided through the poker rod member at an intermediate location thereof and adapted to abut the outer end of the tubular member in the locked position of the poker rod member (Fig 12). 54 is an induction heating arrangement comprising a water cooled hollow induction coil 55 wound over insulating material 56 and connected to an AC power supply 57 through a control panel 58 and a main switch 59 (Fig 1). The coil is also connected ,to a water demineralising, cooling and recirculating arrangement 60 (Fig 1). 61 is a temperature probe provided at the bottom of the reactor. Prior to carrying out the process of the invention the lid 3 of the container is detached or opened as described above and the bottom of ( the container is provided with a lining of graphite powder of 4-10 mm thickness corresponding to the clearance between the blades 19a and 19b at the bottom of the agitator shaft and the container bottom. The lid is refitted to the mouth of the container with the J-clamps. One of the closures Bis removed from the corresponding window 12 and a mixture of aluminium particles and catalyst such as iodine is fed into the container through the open window and the window is refitted with the respective closure by bolts 14a. The reactor is purged with an inert gas like nitrogen introduced through the inert gas inlet. The reactor is heated in a controlled manner by induction heating arrangement 54 to the reaction temperature of 300 to 650° C. The reaction temperature is read on the temperature probe 61. On reaching the reaction temperature, the heating arrangement is turned off and liquid yellow phosphorous is fed into the reactor through the phosphorous feeder spout 47. The sleeve 46 is poked with the poker rod member 48 to ensure that the entire yellow phosphorous flows into the container. The liquid yellow phosphorous vaporizes at the reaction temperature and reacts with the aluminium particles to form aluminium phosphide. During the reaction, the reaction mixture is continuously stirred with the agitator. Because of the offset between the two sets of blades 17a, 17b and 17c and 18a, 18b and 18c almost the entire surface area of the reaction mixture is covered by the blades. Because of this and because of the inclination of 5 - 50 ° at which the blades are mounted to the agitator shaft, the entire reaction mixture is stirred and overturned so as to prevent agglomeration of me reaction mass and formation of Vamps. Hme to induction heating it is possible to precisely control the reaction temperature substantially uniformly both at the bottom and lower sides of the reactor. Being a good thermal conductor, the graphite powder at the bottom of the reactor within the non-stirring zone between the reactor bottom surface and the bottom blades 19a and 19b of the agitator, initially absorbs the heat being supplied to the reactor bottom and gradually substantially evenly releases the heat to the reaction mixture thereby heating it substantially uniformly evenly. During agitation, part of the graphite powder at the bottom of the reactor gets mixed with the reaction mixture and the remaining part of the graphite continues to remain at the bottom of the reactor substantially undisturbed and act as a heat sink. This prevents increase of spot temperature and over heating-and melting of the aluminium powder and resultant agglomeration of the reaction mass and wastage of heat. Due to the precise temperature resultant agglomeration of the reaction mixture and aluminium phosphide at the lower sides of the reactor is also avoided. During introduction of the liquid yellow phosphorous , due to the exothermic nature of the reaction if at all there will be sudden spot temperature increase within the reactor, the remaining part of the graphite powder which got mixed with the reaction mixture, initially absorbs the heat and gradually substantially uniformly evenly releases the heat to the reaction mixture and thus acts as a heat sink and controls the reaction temperature. The graphite powder also acts as a barrier to cohesion of aluminium particles and aluminium phosphide particles. Continuous agitation of the reaction also helps to prevent agglomeration. Due to prevention of agglomeration, the product is also free flowing and its discharge is smooth. Also due to the controlled heating and prevention of overheating , wastage of heat is avoided and maximum aluminum particles are available for the reaction. The yield and process efficiency are thus improved. The process is economical besides being safe. Due to the reactor and reactor bottom being cylindrical and spherical respectively and the blades at the bottom of the agitator shaft being of a profile corresponding to the reactor bottom, agitation and overturning of the reaction mixture is smooth and easy. On completion of the reaction the reactor is allowed to cool down to about 200 - 350 ° C. The plug is detached from the discharge opening and the product is allowed to flow down through the discharge opening. The product is poked down if required by the poker rod 39 of the poker arrangement 38 to ensure that the entire product is discharged from the container. The product is also poked down using poker rods ( not shown) through the windows after removing the respective closures . Since the windows are arc shaped and disposed opposite to each other the poker rods introduced through the windows cover almost the entire surface area within the container so as to ensure that no product remains in the container during discharge. Aluminium phosphide is formulated into dosages such as tablets using graphite powder and other formulating agents such as ammonium carbonate or aluminium stearate. Due to the process of the invention being carried out in the presence graphite powder, aluminium phosphide is formed in combination with the graphite powder. The graphite powder is also discharged with the aluminium phosphide. Therefore, there is no need for addition of graphite powder into the aluminium phosphide at the time of formulating it into dosages such as tablets. The quantity of graphite powder taken in the reactor for the reaction would have to be obviously predetermined having regard to the quantity of graphite powder otherwise would have required for formulating the aluminium phosphide into dosages such as tablets. Due to the controlled heating and controlled temperature rise in the reactor excess pressure build up is prevented and the invention eliminates the excess pressure relieving rupture disc. Water (not shown) is demineralised, cooled and recirculated through the hollow induction coil by operating the arrangement 60 to prevent overheating of the induction coil. The demineralising, cooling and recirculating arrangement is known and works in known manner. Any demineralising, cooling and recirculating arrangement may be used to cool the induction coil. Besides being cylindrical with torispherical bottom the container may be of other geometry like rectangular or square. The lid may be fitted to the container vapour tight by a different arrangement. The profiles of the blades at the bottom of the agitator shaft are to register with the container bottom so as to maintain the clearance between the said blades and container bottom and to ensure smooth operation of the said blades. The windows and closures also may be of other geometry besides being arc shaped. The tubular member of the product poker arrangement and the sleeve of the phosphorous feed cum poker arrangement may be of single piece construction. The agitator, detachable plug at the bottom of the reactor and product poker arrangement and the phosphorous feed cum poker arrangement may be of different constructions. The geared motor shaft may be of single piece construction. The coupling between the agitator shaft and geared motor shaft may be coupled out outside the reactor and within the platform of the geared motor. The vent line may be of two or multiple piece construction and may be provided with access passages for poking, backwash or the like. Besides graphite powder any other carbon powder of similar properties may be used in the invention. Such variations of the invention are to be construed and understood to be within the scope of the invention. The following examples are illustrative of the invention but not limitative of the scope thereof. EXAMPLE 1 The reactor of Fig 1 was covered with a layer of 3.8 Kg graphite powder at the inside bottom thereof. A mixture of 38 kg of coarse aluminium powder and 0.57 Kg of iodine was added onto the graphite powder and induction heated to about 590°C under nitrogen environment at atmospheric pressure and under agitation. 32.4 Kg of molten yellow phosphorous (maintained at 80 - 90°C) was introduced into the reactor over a period of 7 hrs, maintaining the temperature of the reaction mass at 525 - 600°C. After completion of addition of yellow phosphorous, the reaction mass was maintained at about 525 -6WPC for another 1 "nr to ensure complete reaction. Agitation was continued throughout the reaction. The product was removed at 200 -300°C (discharge temperature) under nitrogen atmosphere through the discharge opening. Yield - 73.3 free flowing material containing 86% aluminium phosphide with bulk density of 0.8 g/cc. 63.3 Kg was free flowing powder and 10 Kg was easily breakable lumps. EXAMPLE 2 The reactor of Fig 1 was covered with a layer of 4 Kgs graphite powder at the inside bottom thereof. A mixture of 40 kgs of coarse aluminium powder and 0.6 kg of iodine and was added onto the graphite powder and induction heated to about 590°C under nitrogen environment at atmospheric pressure and under agitation. 34 kgs of into the reactor over a period of 10 hrs, maintaining the temperature of the reaction mass at 525 - 600°C. After completion of addition of yellow phosphorous, the reaction mass was maintained at about 525 -600°C for another 1 hr to ensure complete reaction. Agitation was continued throughout the reaction. The product was removed at 200 -350°C (discharge temperature) under nitrogen atmosphere through the discharge opening. Yield - 78 Kg free flowing material containing 86% aluminium phosphide with bulk density of 0.8 g/cc. 70 kg was free flowing powder and 8 kg was easily breakable lumps. WE CLAIM: 1. A process for the preparation of pesticidal aluminium phosphide comprising reacting aluminium powder and yellow phosphorous at 300 to 650 ° C in an inert atmosphere and in the presence of a catalyst, wherein the reaction is carried out in the presence of graphite powder under controlled induction heating and continuous agitation of the reaction mixture. 2. A process for the preparation of pesticidal aluminium phosphide substantially as herein described. 3. A vertical reactor for carrying out the process of preparation of pesticidal aluminium phosphide as claimed in claim 1 comprising a container made of a corrosion resistant thermal conductor material and fitted vapour tight with a detachable lid provided with a vent nozzle connected to a water seal through a vent line having an inert gas inlet and further provided with a pair of oppositely disposed windows with closures, an agitator provided in the container and comprising a plurality of blades fitted to the agitator shaft which is coupled to the shaft of a geared motor mounted on the lid gas tight with the container, a detachable plug for the discharge opening of the reactor, a product poker arrangement provided at the bottom of the reactor, phosphorous feed cum poker means provided at the bottom of the reactor, an induction heating arrangement comprising water cooled 'noTiow induction coil wound around the lower part of the container over insulating material, the coil being connected to an AC power supply through a control panel and a main switch and also to a water demineralising, cooling and recirculating arrangement and a temperature probe provided at the bottom of the reactor. 4. A reactor as claimed in claim 3, wherein the agitator comprises two sets of blades disposed one below the other with respect to the agitator shaft, each set comprising 3 blades arranged equidistantly in the vertical plane and fitted to the agitator shaft at an angle of 5 - 50 ° with the axis of the agitator shaft, the lower set of blades being offset with the upper set of agitator blades and the agitator further comprising two blades disposed oppositely at the bottom of the agitator shaft defining a clearance between 4 to 10 mm with the container bottom and filled to the agitator shaft at an angle of 5 - 50 ° with the axis of the agitator shaft, the profiles of the two blades at the bottom of the agitator shaft registering with the container bottom profile. 5. A reactor as claimed in c\aim 3 or 4, wherein the container is made of corrosion resistant thermal conductor material such as mild steel. 6. A reactor as claimed in claims 3 to 5, wherein the container is cylindrical and provided with a flange at the mouth thereof and a tori spherical bottom and the blades at the bottom of the agitator shaft are curved corresponding to the spherical container bottom. 7. A reactor as claimed in any one of claims 3 to 6, wherein the lid is detachably fitted to the container against a gasket by J - clamps pivoted on lugs at the outer surface of the container. 8. A reactor as claimed in any one of claims 3 to 7, wherein the windows and the respective closures are arc- shaped. 9. A reactor as claimed in any one of claims 3 to 8, wherein the blades are fitted at an angle of 45° with the axis of the agitator shaft. 10. A reactor as claimed in any one of claims 3 to 9, wherein the blades at the bottom of the agitator shaft defines a clearance of 5 mm with the bottom of the container. 11. A reactor as claimed in any one of claims 3 to 10, wherein the geared motor shaft extends into the container and the geared motor shaft and agitator shaft are coupled together within the container. 12. A reactor as claimed in any one of claims 3 toll, wherein the detachable plug is inverted Tee in cross section, the vertical limb of the plug being adapted to fit into the discharge opening and the horizontal limb of the plug being adapted to overlap the discharge opening and register with a rim at the outer surface of the bottom of the discharge opening and provided with handles and further provided with oppositely disposed open slots at the periphery thereof, the plug being detachably fitted to the bottom of the reactor against a gasket by engaging bolts pivoted at the bottom of the reactor in the corresponding open slots in the horizontal limb and tightening wing nuts provided at the distal ends of the bolts against the bottom of the horizontal limb. 13. A reactor as claimed in any one of claims 3 to 12, wherein the product poker arrangement comprises a tubular member fitted at the bottom of the reactor and opening into the reactor and a poker rod reciprocatably held in the tubular member through a gas tight seal located in the tubular member, the tip of the poker rod being extendable into the reactor bottom, the outer end of the poker rod being provided with a handle and the poker rod being provided with a locking pin engagable in a lateral hole provided through the poker rod at an intermediate location thereof and adapted to abut the outer end of the tubular member in the locked position of the poker rod and the phosphorous feed cum poker means comprises a sleeve provided with a phosphorous feeder spout projecting from its side, the sleeve being fitted to and opening into the tubular member, a poker rod member reciprocatably held in the sleeve through a gas tight seal located in the sleeve, the tip of the poker rod member being extendable into the tubular member, the outer end of the poker rod member being I provided with a handle, the poker rod member being further provided with a locking pin engageable in a lateral hole provided through the poker rod member at an intermediate location thereof and adapted to abut the outer end of the sleeve in the locked position of the poker rod member. 14. A vertical reactor for the preparation of pesticidal aluminium phosphide substantially as herein described. Dated this 26* day of April 2004 (Jose M A) of Khaitan & Co Agent for the Applicants

Documents:

492-mum-2004-abstract(17-12-2004).doc

492-mum-2004-abstract(17-12-2004).pdf

492-mum-2004-cancelled pages(17-12-2004).pdf

492-mum-2004-claims(granted)-(17-12-2004).doc

492-mum-2004-claims(granted)-(17-12-2004).pdf

492-mum-2004-correspondence(19-09-2005).pdf

492-mum-2004-correspondence(ipo)-(05-09-2005).pdf

492-mum-2004-drawing(17-12-2004).pdf

492-mum-2004-form 1(11-05-2004).pdf

492-mum-2004-form 1(19-09-2005).pdf

492-mum-2004-form 1(28-04-2004).pdf

492-mum-2004-form 19(20-05-2004).pdf

492-mum-2004-form 2(granted)-(17-12-2004).doc

492-mum-2004-form 2(granted)-(17-12-2004).pdf

492-mum-2004-form 26(11-05-2004).pdf

492-mum-2004-form 26(19-09-2005).pdf

492-mum-2004-form 3(11-05-2004).pdf

492-mum-2004-form 3(19-09-2005).pdf

492-mum-2004-form 3(28-11-2004).pdf

492-mum-2004-form 8(20-05-2004).pdf

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