Apparatus for grinding material

Technical field

[0001 ] This invention relates to an apparatus for grinding and processing different materials and in particular green materials such as corn with root components, sunflowers, reeds, rushes, conifer boughs, vegetable and fruit waste for the purpose of preparing animal food. Other suitable materials for processing also include grains, manure, waste fish products including fish oil and bones and flour etc. The apparatus may also be used to process solid industrial and domestic waste.

Background Art

[0002] Numerous designs of grinding-milling apparatus are known, however these have a large power consumption and insufficient dispersion grade. Apparatus for green material processing also suffer from the problem that the blades which are used as working elements wear out quickly.

[0003] Classic grinders, mills and other apparatus with a restricted applicability are widely known, their restricted applicability is their disadvantage, as well as their low milling grade.

[0004] Material grinding apparatus (shredder) as per Patent RU2492927 dated

16.06.201 1 is known. The shredder rollers consist of a shaft, discs with different tooth parameters and intermediate rings. The discs are positioned on the shaft in sections with the discs with similar parameters joined into one section. The combination of numerous sections on one roller enables multi-stage grinding and milling in the same grinder. The apparatus does not enable grinding or milling of the materials, particularly, timber wastes and used tyres on the section most appropriate for the task. However, a disadvantage of this apparatus is the fact that the shredder working surface made up by the discs and roller intermediate rings has a low dragging ability. The ground material may slip out of the gaps between the roll discs. Then again being affected by the roller discs the material being ground slips out of them some more times or is finally dragged into the gaps between the discs and finally ground. Therefore the process of the material dragging may be repeated several times which reduces the shredder throughput. Besides, multiple slipping of the material being ground out of the gaps between the rollers discs results in the material accumulation on the shredder working surface which requires the process intermission to remove the material off the working surface. It increases the time and labour

consumption for the plant disposal process and consequently operation costs of the known shredder.

[0005] From Eurasian patent EA0151 1 dated 03.1 1 .2006 an apparatus for milling

fodder crops is known. The apparatus is equipped with two milling rollers rotating in directions facing each other, with the tooth profiles and blades inside them directed along the axis and engaged in a clutching arrangement with each other, hereby the teeth's side surfaces of one of these milling rollers have concave sections while the side surfaces of the teeth on the other roller have the convex ones. Besides, the teeth side surfaces have radial inner and/or radial outer rectilinear sections. The milling rollers consist of predominantly stand-alone disc elements.

[0006] A disadvantage of this apparatus is a low grinding grade and restricted

applicability.

[0007] A milling apparatus as per the USSR Certificate of Authorship SU710629 dated 21 .10.1977 is known. The mill consists of a frame on which spring-loaded rollers with a set of blades in longitudinal toothed and transverse toothed are installed as well as a drive.

[0008] A disadvantage of this apparatus is an insufficient grinding grade and restricted applicability (for timber processing only).

[0009] Therefore, a topical task of the present-day technologies and this invention is increased service life, capacity and grinding quality of the final product as well as the apparatus versatility which consists in the expansion of the technological capabilities of the apparatus due to the expansion of the range of the materials to be processed. [0010] Besides, the task of this invention is the creation of efficient and reliable means to produce submicron and nanopowder wastes of vegetable-origin production which enables price and energy cost reduction.

Disclosure of the invention

[001 1 ] This invention provides an apparatus for grinding material, wherein the

apparatus comprises an upper chamber having an inlet, the upper chamber containing a plurality of multi-armed rotors mounted on a central shaft capable of being rotated by at least one driving means and a lower chamber having an outlet, the lower chamber being in fluid communication with the upper chamber and containing two longitudinally arranged screw conveyors capable of being rotated by at least one driving means.

[0012] In a further embodiment of the invention, the upper chamber comprises a

grinding chamber and a preliminary milling chamber separated by a filter.

[0013] In a further embodiment of the invention, ultraviolet radiation units are provided in the grinding chamber.

[0014] In a further embodiment of the invention, the arms of the rotors are inwardly curved and tapered.

[0015] In a further embodiment of the invention, one or more rollers are interspersed between the rotor arms and are capable of rotating around the inner wall of the upper chamber in the same direction and at the same speed as the rotors.

[0016] In a further embodiment of the invention, the one or more rollers are provided in the concave section of each of the rotor arms

[0017] In a further embodiment of the invention, the rollers are capable of rotating about their rotational axis.

[0018] In a further embodiment of the invention, the screw conveyors rotate in opposite directions.

[0019] In a further embodiment of the invention, at least one of the screw conveyors is a centerless screw conveyor.

[0020] In a further embodiment of the invention, at least one of the screw conveyors has a central shaft. [0021 ] In a further embodiment of the invention, one or more brushes are mounted on the screw conveyors.

[0022] In a further embodiment of the invention, material is capable of flowing through the upper chamber in a first direction and through the lower chamber in a second direction.

[0023] In a further embodiment of the invention, the one or more driving means

comprise one or more motors.

[0024] In a further embodiment of the invention, one or more motors comprise

electrical motors.

[0025] In a further embodiment of the invention, the lower chamber comprises one or more closable orifices.

Brief description of the drawings

[0026] The invention will now be described by way of example with reference to the accompanying drawings:

Figure 1 shows a side view of an embodiment of the invention;

Figure 2 shows a cross section along the line A-A in Figure 1 ; and

Figure 3 shows an expanded view of the grinding chamber shown in Figure 2. Mode(s) for carrying out the invention

[0027] According to a first embodiment of the invention there is provided an apparatus for grinding material, wherein the apparatus comprises an upper chamber having an inlet, the upper chamber containing a plurality of multi-armed rotors mounted on a central shaft capable of being rotated by at least one driving means and a lower chamber having an outlet, the lower chamber being in fluid communication with the upper chamber and containing two longitudinally arranged screw conveyors capable of being rotated by at least one driving means.

[0028] In an embodiment of the invention shown in Figure 1 there is provided an upper chamber (17) having an inlet (10) and a lower chamber (5) in fluid

communication with the lower chamber via a passage (4). The upper chamber contains a plurality of multi-armed rotors (20) mounted on a central shaft (19) capable of being rotated by at least one driving means (6). The lower chamber has an outlet (8) and also contains two longitudinally arranged screw conveyors (23) which are capable of being rotated by at least one driving means (7). The apparatus may be supported by a base (1 ). In the embodiment of the invention shown in Figure 1 an outlet transport (9) is also provided for conveying output ground material away from the outlet. In the embodiment of the invention shown in Figure 2 windows (26) are provided in the upper chamber.

[0029] Material is fed into the first chamber via the inlet and progresses along the first chamber to the passageway between the first and second chambers. Once in the passageway the material progresses into the second chamber

predominantly under the force of gravity but it may also be pushed into the lower chamber under the force of material flowing through the upper chamber. Material then flows through the lower chamber from the passageway and towards the outlet. Material exiting the outlet may then optionally be transferred away from the outlet by an outlet transport. In an embodiment of the invention material is capable of flowing through the upper chamber in a first direction and through the lower chamber in a second direction. In the embodiment of the invention shown in Figure 1 , the material flows through the upper chamber in an opposite direction to the material flowing through the lower chamber. With this arrangement the lower chamber is provided directly beneath the upper chamber which provides a more compact apparatus.

[0030] In a further embodiment of the invention, the upper chamber comprises a

preliminary milling chamber (2) and a grinding chamber (3) separated by a filter (16). The preliminary milling chamber is the section of the apparatus where the largest size material, i.e. that first introduced to the apparatus via the inlet, is initially ground up. The pore size of the filter is selected such that only material smaller that the pore size is able to progress from the preliminary milling chamber into the grinding chamber. The filter acts to not only prevent material larger than a certain size passing from the preliminary milling chamber and the grinding chamber but also to separate out these two zones. [0031 ] The grinding chamber is where the second stage of grinding occurs on smaller sized material which has been able to pass through the zone separation filter. Preferably ultraviolet radiation units (12) are provided in the grinding chamber for sterilizing and decontaminating the material passing through the upper chamber. The inclusion of this feature is particularly desirable where the material being ground and processed is liable to contain lots of bacteria and other micro-organisms, for example material such as fish industry waste and poultry offal. In the embodiment of the invention shown in Figure 2 windows (26) are provided in the upper chamber.

[0032] In the embodiment of the invention shown in Figure 1 , a central shaft (19)

extends longitudinally through the preliminary milling chamber and the grinding chamber. A plurality of multi-armed rotors are mounted upon the central shaft. The number of rotors provided on the shaft is selected depending on the type of material that is to be ground by the apparatus. Preferably at least one rotor is provided in the preliminary milling chamber and at least one further rotor is provided in the grinding chamber. Furthermore for each of the rotors mounted on the central shaft the number of rotor arms each has is selectable depending on the type of material which is to be ground.

[0033] The central shaft is capable of rotating the rotors mounted upon it by the action of at least one driving means. In an embodiment of the invention the driving means is a motor, preferably an electric motor is used. The central shaft may be rotated at different speeds (measured in revolutions per minute).

[0034] The rotors are multi-armed rotors with the number of arms being selectable depending on the type of material to be ground up. In a preferred embodiment of the invention the arms of the rotors are inwardly curved and tapered towards the end of the rotor arms. Figures 2 and 3 show embodiments of the invention where the rotors have three arms and in each case the arms are inwardly curved and tapered. Preferably the inwardly curved section of the rotor arms are formed as blades.

[0035] In a further embodiment of the invention one or more rollers (28) are

interspersed between the rotor arms and are capable of rotating around the inner wall of the upper chamber in the same direction and at the same speed as the rotors, In the embodiment of the invention shown in Figures 2 and 3, three rollers are interspersed between each of the three rotors arms provided.

Preferably the number of rollers provided will correspond to the number of rotor arms with the rollers interspersed between the rotor arms. In a preferred embodiment the one or more rollers are provided in the concave section of each of the rotor arms as shown in Figures 2 and 3. Preferably the rollers are capable of rotating about their rotational axis. In this embodiment the rollers rotate passively when encountering material which is being ground in the preliminary milling chamber. In this manner, the rollers interact with the rotor arms to provide enhanced grinding of the material in the preliminary milling chamber because material captured by the rotor arm is then forced under the freely rotating roller causing the material to be compressed and thus ground down.

[0036] In an alternative embodiment of the invention, the rollers are attached to the wall of the upper chamber instead of being provided in the concave section of each of the rotor arms. The rollers are able to rotate freely about their rotational axis and rotate passively such that they only rotate when forced to do so by material being forced underneath. In this embodiment the arms of the rotors do not extend radially all the way to the upper chamber wall meaning that the rotor is able to rotate (being driven by the driving means) as there is some clearance between the rotor arms and the rollers attached to the periphery of the upper chamber.

[0037] In a yet a further embodiment of the invention, the rollers are again attached to the wall of the upper chamber instead of being provided in the concave section of each of the rotor arms. The rollers are able to rotate freely about their rotational axis and rotate passively such that they only rotate when forced to do so by material being forced underneath. In this embodiment of the invention one or more groups of rollers are spaced longitudinally along the upper chamber. Preferably the number of roller groups corresponds to the number of rotors mounted on the central shaft. Preferably the number of rollers in a roller group corresponds to the number of rotor arms on a corresponding rotor. In this embodiment of the invention the roller groups are offset longitudinally in the upper chamber from the rotors mounted on the central shaft such that the rotary motion of the one or more rotors is not impeded by the one or more roller groups attached to the wall of the upper chamber.

[0038] The various working elements in the upper chamber, i.e. the rotors and central shaft but also optionally other elements such as the rollers all generate heat through their mechanical action and friction. The heat generated helps to remove moisture from the material.

[0039] The lower chamber is in fluid communication with the upper chamber via the passageway. By the time the material reaches the lower chamber it is partially ground and it is in the lower chamber that the final processing and fine grinding of the material occurs. The final processing of the material includes removing moisture to produce powdered material or optionally forming the material into pellets.

[0040] The lower chamber contains two longitudinally arranged screw conveyors

capable of being rotated by driving means. Preferably the driving means is a motor, more preferably an electric motor is used. Ideally the screw conveyors extend along the entire length of the lower chamber or a substantial portion of the lower chamber. The material is dried out as it progresses along the screw conveyors as the screw conveyors help to separate out the material which otherwise might stick together. The heat generated by the mechanical action and friction of the screw conveyors also helps to dry out the material as it flows through the lower chamber towards the outlet.

[0041 ] The screw conveyors are capable of being rotated at different speeds (in

revolutions per minute), the speed is selected according to the degree of moisture required in the output material. Where the screw conveyors rotate at a higher speed the material will progress through the lower chamber quickly and the output material will contain some moisture as there will be little drying out time. Where drier material is desired the speed at which the screw conveyors rotate should be reduced to provide more drying time. [0042] The lower chamber comprises a first longitudinally extending semi-chamber unit (13) and a second longitudinally extending semi-chamber unit (15). Preferably one screw conveyor is located in the first semi chamber unit and the other screw conveyor is located in the second semi chamber unit. The screw conveyors used may either be centerless screw conveyors or screw conveyors having a central shaft (for example an Archimedean screw). In the embodiment of the invention shown in Figure 2 the screw conveyors have central shafts (21 , 22).

[0043] In the embodiment of the invention shown in Figure 1 the passageway between the upper and lower chambers is provided at a first end of the lower chamber whereas the outlet is provided at the second, opposite end of the lower chamber. In this embodiment of the invention the screw conveyors are arranged such that material entering the lower chamber via the passageway is caused to progress along the lower chamber towards the outlet by the rotating action of the screw conveyors. In yet another embodiment of the invention the screw conveyors rotate in opposite directions, i.e. one of the screw conveyors rotates in the clockwise direction while the other screw conveyor rotates in the anticlockwise direction.

[0044] In a further embodiment of the invention one or more brushes are mounted on the screw conveyors. The inclusion of brushes improves the grinding efficiency of the apparatus and causes the material to be fine ground in the lower chamber. The material becomes fine ground where it falls between the screw conveyor and the one or more brushes. Preferably the brushes are wire brushes formed from metal. In one embodiment of the invention the bristles of the brushes are formed as loops. In another embodiment of the invention the bristles of the brushes have side-branches. The bristles of the brushes may also be formed as loops having side branches. The number of brushes incorporated into the apparatus and their complexity (in terms of number of loops and side branches) will be selected dependent on the intended use of the apparatus, i.e. the type of material to be ground. [0045] Optionally the lower chamber may comprise one or more closable orifices (25). The orifices are for the embodiment of the invention where it is intended that the material will be formed into pellets rather than as finely ground material (i.e. material directed by the screw conveyors towards the outlet). In this

embodiment of the invention the outlet in the lower chamber is closed off and the speed of rotation of the screw conveyors is reduced such that ground material starts to accumulate in the lower chamber (rather than being forced towards the outlet). Preferably the rotational direction of the screw conveyors is selected such that they force material towards the bottom of the lower chamber. Upon opening the orifices pellets are produced as a result of material being forced through the orifices. The orifices are capable of having different diameters (for different pellets sizes) and optionally the orifices may have adjustable diameters.

[0046] This invention provides an apparatus having separate zones for grinding and processing the material; grinding primarily occurs in the upper chamber whereas further processing such as drying and fine grinding occurs primarily in the lower chamber. The arrangement ensures that a wider range of materials can be ground and processed by the apparatus and the separation of upper and lower chambers also ensures that the apparatus has a greater capacity. The milling quality, grinding grade, reliability and service life are also all improved. The zone separation ensures that the load of material being ground and/or processed by each of the various working elements is reduced which in turn reduces the wear of these working elements. This has the additional advantage that operation down time is decreased as the parts need replacing less frequently.

[0047] According to further embodiments of the invention there are provided further sub-zones within the apparatus. The upper chamber may be divided into a preliminary milling chamber and a grinding chamber. The lower chamber may comprise two semi-chamber units. By further sub-dividing either one or both of the upper and lower chambers the various grinding and processing stages are further subdivided. For example the largest material is ground in the preliminary milling chamber and only material small enough is able to progress to the grinding chamber which is in turn more efficient as only smaller sized material is present. Further improvements and efficiency savings are therefore acquired by further separating the various aspects of grinding and processing the material by having additional zones.