GB1583745A

GB1583745A - Apparatus for mixing materials

Info

Publication number: GB1583745A
Application number: GB19269/76A
Authority: GB
Original assignee: BOULTON Ltd W
Current assignee: BOULTON Ltd W
Priority date: 1976-05-11
Filing date: 1976-05-11
Publication date: 1981-02-04
Also published as: JPS6032490B2; JPS52148867A; CH611179A5; BE854502R; FR2350871A2; FR2350871B2; IT1115473B; DE2720685A1; NL7705238A; ES458647A2

Description

(54) APPARATUS FOR MIXING MATERIALS (71) We WILLIAM BOULTON LIMITED, a British Company of Providence Engineering Works, Navigation Road, Burslem, Stoke-on Trent, Staffordshire, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The invention relates to apparatus for mixing materials.

Various types of mixing machine are available for mixing granular or other particulate materials. Some such machines operate by applying a vibratory movement to a charge of the materials to be mixed contained in a mixing or treatment chamber. While such machines operate effectively in mixing different granular materials or different powdered materials where the materials to be mixed are of similar density, a problem arises in mixing materials of different density in that the materials tend to separate, the heavier material collecting at the bottom of the treatment vessel and the lighter material rising to the top.

It is an object of the present invention to provide apparatus which may be used for the mixing of different density materials without giving rise to the problem of separation of the materials referred to above.

The invention provides mixing apparatus comprising a resiliently mounted treatment chamber of annular shape in plan with inner and outer side walls and an arcuate bottom, means for subjecting the chamber to a compound vibratory movement of high frequency and low amplitude comprising a rotary oscillation about a substantially vertical axis with an upward and downward component in the movement, whereby to cause a charge of materials in the chamber to travel around the chamber while undergoing orbital movements in generally vertical planes substantially at right angles to the direction of travel round the chamber, and including fixed baffles in said chamber serving to prevent the creation of a dead zone in the central region of the charge of materials.

The apparatus preferably includes a removable top or closure for the chamber and may include means enabling one or more of the internal conditions of temperature, moisture content and pressure in the chamber to be varied.

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings in which: Figure 1 is a schematic sectional elevation through one form of apparatus which may be used to carry out the method according to the invention; Figure 2 is a diagrammatic plan view of the apparatus shown in Figure 1; and Figures 3 and 4 are views similar to Figure 1 showing modified forms of apparatus.

Referring to Figures 1 and 2 the apparatus comprises a base 2 of generally cylindrical shape having an encircling horizontal flange 3 at the top on which are located a number of vertical coil springs 4 forming an annular series.

The upper ends of the springs are connected to an annular horizontal plate 5 having attached to it a central cylindrical sleeve 6. The sleeve has attached to its inside wall upper and lower mounting brackets or collars 7, 8 which carry an electric motor 9, the axis of the motor spindle 10 being vertical and on the vertical centre line of the machine. The spindle 10 carries upper and lower weights 11, 12, independently adjustable angularly so that they can be set out of balance to create or vary the vibratory motion of the plate 5 and the superstructure which it carries, resting on the springs 4. The rotating out-of-balance masses represented by the weights 11, 12 set up a vibratory motion of a rotational character with an upward and downward component in the movement, which is of high frequency and low amplitude.

The sleeve 6 supports a treatment chamber 13 surrounding a central space 14 formed by the inner wall 1 3a of the chamber, the said inner wall 13a and the outer wall 1 3b of the chamber being vertical at their upper parts and smoothly curved at their lower parts to form a semi-toroidal base 1 3c. The upstanding walls enable operation of the machine at the desired frequency without discharging the mixture and assist in generation of the desired movement of the charge. The interior of the chamber is provided with a lining 1 3d of synthetic rubber vulcanised to the chamber.

Fixed baffles 1 3e are mounted within the chamber 13 and are spaced apart at 1200 inter vals. The baffles comprise blade members of inverted V form and are secured to the curved part 1 3c of the chamber by gussets 13fat each end. The baffles are positioned such that their apices co-incide approximately with the centre of mass of the charge of materials to be mixed.

Provision of the baffles does not impair the flow of material around the chamber but serves to baffle the central core of the vibrating mass during its movement and prevents the creation of a "dead" zone. This has been found not only to improve the blending and mixing of different materials having variable particle size and density, but also to greatly reduce the time required to achieve homogeneous mixing.

A hopper 15 is provided which is designed to contain a supply of the different density materials to be mixed. One of the materials is delivered by gravity to a measuring vessel 15A which measures a quantity of the material by volume or weight as desired, and delivers it by way of a chute 15B to the chamber 13. A separate container 16 having an associated feed device 17 feeds a controlled volume or weight of the other material to the chamber 13. After the mixing operation has been completed the material is discharged through a door 18 (figure 2). A control system indicated generally at 19 is provided and incorporates timing mechanisms, valves, switches, relays or any other means of enabling the operating cycle of the apparatus to be adjusted to suit different constituents and mixing periods or other variables, and to initiate automatic loading and discharge of the materials.

Thus in operation the desired quantities of the different density materials to be mixed are introduced into the treatment chamber and the chamber is set in vibration. During operation of the machine the charge moves around the chamber and also undergoes orbital or circular movement in generally vertical planes substantially at right angles to the direction of movement round the chamber. The nature of this movement together with the interaction with the baffles 1 3e produces particularly effective mixing of the materials.

The combined orbital and translatory movement of the charge in the chamber is a smooth continuous movement and is obstructed only by the action of the fixed baffles so that uniform and thorough mixing is achieved. There are no movable stirrers or other mechanical agitators projecting into the bowl such as would interfere with the relatively smooth continuous movement of the charge and thereby reduce the effectiveness of the process.

The frequency and amplitude of the vibratory movement may be varied to meet different requirements but frequencies generated by a motor speed of the order of 900 - 3000 revs./min. and having an amplitude of vibration of about 64 to 3 inch would be appropriate for most mixing operations.

When the treatment has proceeded for a sufficient length of time (which will vary in accordance with the materials concerned and the extent of mixing desired) as determined by presetting of the control system 19, the discharge door 18 is opened while the motor continues to run, and the mixed materials then discharge automatically under the influence of the vibratory movement. The apparatus is then ready for treatment of the next batch.

Generally the charge will circulate several times round the chamber before discharge, but in some instances satisfactory mixing may be achieved with only one circuit of the chamber.

In such cases the chamber may be closed at the inlet region and arranged such that the discharge region is open-ended, whereby no recirculation takes place and continuous rather than batch treatment may be achieved. The rate at which the charge moves around the chamber can be controlled by adjustment of the weights 11,12.

The machine shown in Figures 1 and 2 is arranged to operate automatically so that loading, mixing and unloading all take place in accordance with the settings of the control system 19. It will be appreciated however that loading may be effected manually if desired and the measuring and loading equipment 15 - 17 could be dispensed with in less sophisticated machines.

Figure 3 shows a modified form of apparatus in which the chamber 20 is generally cylindrical and has a conical or convex bottom 21 and a helical channel 22 extending up and around the chamber walls. The materials to be mixed are fed into the chamber through the centre of the helical from supply systems 23 and 24 and the chamber is mounted on springs 25 and vibrated by a motor carrying eccentric weights as described with reference to Figure 1. The chamber and/or channel are lined with rubber.

In operation the vibratory movement and the conical floor cause the charge to move outwardly to the chamber wall and to travel up and around the channel 22 while undergoing orbital movement in generally vertical planes.

There may be any number of turns to the helical channel and on reaching the top, mixing is complete and the mixed material is discharged through an outlet 26. The directions of movement of the materials through the apparatus are indicated by the arrows.

Figure 4 shows a further modification in which a chamber 30 similar to that of Figure 1 and 2 is used but has a helical floor 31. The materials are fed from supply systems 32 and 33 to a delivery chute 34 leading to the lower end of the helix, and the mixed material is discharged through an outlet 35 at the upper end of the helix. In other respects the machine is constructed and functions in the manner of the Figures 1 and 2embodiment.

Although not shown in the drawings the vibrator unit consisting of the motor and eccentric weights is preferably adjustably mounted on the machine so that it can be moved to different vertical positions dependent on the densities and particle sizes of the material to be mixed. This enables variation of the vibratory movement to suit the nature of the charge and enables rapid and effective mixing of a wide range of different materials.

The machines described enable rapid and effective mixing to be achieved and, particularly in the case of the Figures 1 and 2 embodiment, are easily cleaned. Ease of cleaning is important where batches of different materials require to be mixed successively in the same machine.

Various modifications may be made without departing from the invention. For example though the treatment chambers may be opentopped, they are preferably closed by a removable top having one or more inspection windows therein. The top may be removed for cleaning or repair purposes and when in place enables the temperature, pressure or moisture content of the air in the chamber to be controlled.

Though reference has been made to vibration by use of an electric motor fitted with eccentric weights, the necessary movement may be induced in other ways, for example by use of electromagnetic or piezo-electric vibrators or by use of air or hydraulic motors fitted with weights. The angular positions of the weights could be arranged to be adjustable by remote control during operation or on reversing rotation of the motor, for example to alter the nature of the vibration at different stages in the process or to enable discharge of the mass by causing it to climb over an inserted dam or weir to a high level discharge zone. The chamber could also be mounted on air springs instead of the coil springs described, or could be otherwise resiliently supported.Where discharge is effected through a door similar to that shown in Figure 2, the door is preferably a power-operated quick-opening door, but could be manually operated if desired. In a further modification the vibrator motor or other vibrator unit may be located within the space 14. In the case of the Figure 4 embodiment the materials could be fed into the machine at the upper end of the channel and the mixed materials discharged at the lower end.

WHAT WE CLAIM IS: 1. Mixing apparatus comprising a resiliently mounted treatment chamber of annular shape in plan with inner and outer side walls and an arcuate bottom, means for subjecting the chamber to a compound vibratory movement of high frequency and low amplitude comprising a rotary oscillation about a substantially vertical axis with an upward and downward component in the movement, whereby to cause a charge of materials in the chamber to travel around the chamber while undergoing orbital movements in generally vertical planes substantially at right angles to the direction of travel round the chamber, and including fixed baffles in said chamber serving to prevent the creation of a dead zone in the central region of the charge of materials.

2. Mixing apparatus according to claim 1 wherein said baffles comprises blade members extending at right angles to the direction of travel of the materials around the chamber.

3. Mixing apparatus according to claim 2 wherein each of said blade members is of inverted V-form.

4. Mixing apparatus according to claim 3 wherein the apices of said V-form blade members are disposed so as to co-incide approx mately with the centre of mass of the charge of materials to be mixed when the treatment chamber is filled to a predetermined level.

5. Mixing apparatus according to any of claims 1 to 4 wherein said blade members are equispaced around said chamber at 1 2or intervals.

6. Mixing apparatus according to claim 5 wherein the floor of said chamber is horizontal.

7. Mixing apparatus according to claim 5 wherein the floor of said chamber is helical.

8. Mixing apparatus according to any of claims 1 to 7 including a removable top closure for said chamber and means enabling one or more of the internal conditions of temperature, moisture content and pressure in the chamber to be varied.

9. Mixing apparatus according to any of claims 1 to 8 wherein said means for subjecting the chamber to vibratory movement comprises a motor having its shaft disposed vertically and fitted with upper and lower eccentric weights.

10. Mixing apparatus according to claim 9 wherein said motor and weights are vertically adjustably mounted relative to said chamber.

11. Mixing apparatus substantially as hereinbefore described with reference to Figures 1 and 2 of the accompanying drawings.

12. Mixing apparatus substantially as hereinbefore described with reference to Figure 3 of the accompanying drawings.

13. Mixing apparatus substantially as hereinbefore described with reference to Figure 4 of the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. on the machine so that it can be moved to different vertical positions dependent on the densities and particle sizes of the material to be mixed. This enables variation of the vibratory movement to suit the nature of the charge and enables rapid and effective mixing of a wide range of different materials. The machines described enable rapid and effective mixing to be achieved and, particularly in the case of the Figures 1 and 2 embodiment, are easily cleaned. Ease of cleaning is important where batches of different materials require to be mixed successively in the same machine. Various modifications may be made without departing from the invention. For example though the treatment chambers may be opentopped, they are preferably closed by a removable top having one or more inspection windows therein. The top may be removed for cleaning or repair purposes and when in place enables the temperature, pressure or moisture content of the air in the chamber to be controlled. Though reference has been made to vibration by use of an electric motor fitted with eccentric weights, the necessary movement may be induced in other ways, for example by use of electromagnetic or piezo-electric vibrators or by use of air or hydraulic motors fitted with weights. The angular positions of the weights could be arranged to be adjustable by remote control during operation or on reversing rotation of the motor, for example to alter the nature of the vibration at different stages in the process or to enable discharge of the mass by causing it to climb over an inserted dam or weir to a high level discharge zone. The chamber could also be mounted on air springs instead of the coil springs described, or could be otherwise resiliently supported.Where discharge is effected through a door similar to that shown in Figure 2, the door is preferably a power-operated quick-opening door, but could be manually operated if desired. In a further modification the vibrator motor or other vibrator unit may be located within the space 14. In the case of the Figure 4 embodiment the materials could be fed into the machine at the upper end of the channel and the mixed materials discharged at the lower end. WHAT WE CLAIM IS:

1. Mixing apparatus comprising a resiliently mounted treatment chamber of annular shape in plan with inner and outer side walls and an arcuate bottom, means for subjecting the chamber to a compound vibratory movement of high frequency and low amplitude comprising a rotary oscillation about a substantially vertical axis with an upward and downward component in the movement, whereby to cause a charge of materials in the chamber to travel around the chamber while undergoing orbital movements in generally vertical planes substantially at right angles to the direction of travel round the chamber, and including fixed baffles in said chamber serving to prevent the creation of a dead zone in the central region of the charge of materials.