GB2085741A - A machine for the treatment of wet particulate materials - Google Patents

Abstract

The machine comprising a horizontal drum 1 within which is mounted a rotatable shaft 3 having flat blades 16 projecting therefrom at locations spaced along and around the shaft, the blades being angled to the perpendicular to the shaft to convey material, introduced into the drum at one end 4, to a discharge opening 5 at the other end. The angle of inclination of the blades further from the discharge end is less than that of the blades nearer to the discharge end. <IMAGE>

Description

SPECIFICATION A machine for the treatment of wet particulate materials The invention relates to machines for the treatment of particulate materials, especially dry or wet cohesive materials such as wet coal fines or slurries.

The treatments for which the machine is applicable include blending and breaking down so as to improve their handling characteristics by reducing the materials to a more finely divided, granular or pelletised state.

Certain materials such as wet coal fines, coal slurries and washings, damp foundry sand and damp cenospheres derived from lagooned pulverised fuel exhibit cohesive and binding properties which rendex them unsuitable for immediate and subsequent commercial or industrial use. They require treatment to break down the cohesiveness and to convert them into a more acceptable form. Hitherto this breakdown has been a costly operation achieved by some form of drying and rehandling.

According to the invention there is provided a machine for the treatment of particulate material comprising a drum having charge and discharge openings at its respective ends, a shaft rotatably mounted substantially horizontally along the longitudinal axis of the drum, a plurality of flat blades secured at spaced locations along the length of the shaft to project radially therefrom generally at different orientations about the axis of the shaft, with the plane of each blade inclined to the perpendicular to the shaft axis. The angle of inclination of each blade may be independently infinitely variable. Preferably the plane of the blade nearest to the discharge end of the drum is inclined to the perpendicular in the opposite sense to the inclination of the planes of the other blades.The blades apart from the one nearest to the discharge end of the drum preferably form groups respectively nearer to and further from the discharge end of the drum, and the angle of inclination of the plane of each of the blades of the group further from the discharge end of the drum is less than that of each of the blades of the group nearer the discharge end. The blades of the group nearer the discharge end may be broader and spaced apart more widely than those of the group further from the discharge end.

The orientation of radial projection of each blade relative to that of its neighbour(s) is preferably 90".

The drum may be circular or polygonal in cross section and may be constructed of or lined with material resistant to abrasion or chemical action. The projection of the blades from the shaft may be adjustable to vary the spacing of the blade from the inner surface of the drum, which spacing may be 3mm and is preferably not less than 1 .5mm, and in general may be twice the average particle size of the material being treated.

Embodiments of the invention will now be described by way of example and with reference to the accompanying drawings of which : Fig. 1 is a side elevation of a particulate material treating machine; Fig. 2 is a vertical cross-section on the machine of Fig. 1; Fig. 3 is a detail of the central shaft; Fig. 4 is a detail of a blade for attachment at one end of the shaft; Fig. 5 is an end view of the blade of Fig. 4; Fig. 6 is a plan view of a portion of the shaft showing two blades according to Fig. 4; Fig. 7 is a detail of a blade for attachment to the shaft at the other end of the shaft; Fig. 8 is a detail of the shaft at the said other end showing two adjacent blades according to Fig. 7; and Fig. 9 is a detail of shaft showing a bore with radial slots.

As shown in the figures the machine comprises a horizontal cylinder 1, closed at its ends which support self-aligning bearings 2 in which are mounted a shaft 3. At one end of the cylinder is a feed hopper 4 and at the opposite end a discharge port 5. In the embodiment described the drum is cylindrical, but in other embodiments it may be of polygonal transverse section. The drum may be made of any abrasive resistant structural material such as alloy, steel or plastics and it may be lined or coated, if required, with antifriction or chemically resistant material. The drum is supported by cradles 6.

As shown more particularly in Fig. 3 the shaft 3 comprises stub shaft portions 7 and 8, one end of each of which is secured within respective ends of a tube 9. The tube 9 is provided with through radial bores 10,11 formed perpendicularto the shaft axis and respectively in diametral planes perpendicular to one another.

The group of bores at the end nearer the stub shaft 7 are spaced closer together than the group of bores nearer the stub shaft 8.

A blade as sown in Fig. 4 is secured in each of the group of bores nearer the discharge end of the machine with its centre line arranged perpendicular to the shaft axis and for this purpose the blades 16 are each provided with a stem 17 terminating in a threaded portion carrying a self locking nut 12.

As shown generally in Fig. 1 and in partical detail in Fig. 6, successive blades 16 are secured in the bores 10, 11 in spiral sequence about the tube 9, each blade being oriented at 900 to its neighbour or neighbours. Fig. 6 also shown that the plane of the blade 16 is inclined at 25" to the perpendicular to the axis of the tube 9.

The blade 16 is made of manganese steel plate, the edges of which are cut sharply so that the edges 15 constitute cutting edges as the shaft 3 is rotated in the direction of the arrow 14 in the bearings 2. These edges impart shearing, cutting and shredding action to material contained in the drum. Because ofthe inclination of the blades to the perpendicularto the axis of tube 9, the rotation thereof also effects a motion of the material from the charge end to the discharge end. The outer edge 13 ofthe blades is shaped to correspond substantially to the inner surface of the drum 1 and spaced from it by not more than about 3mm.In general the blades are as close as possible to the drum inner surface to prevent build up of material on the surface which would result in excessive wear of the blades, but in practice there may need to be a clearance of not less than about 1.5mum and generally approximately twice the average particle size of the material to be treated in the machine.

The blade 19 nearest to the discharge end ofthe machine is similar in all respects to the blades 16 but its plane is set at 25O on the opposite side of the perpendicular. This reversal of the inclination to the perpendicular assists in the discharge of material from the interior of the drum through the discharge orifice 5, and prevents build-up of material on the end ofthe machine.

The blades 20 are similarly secured in the holes 10, 11 at the end of the shaft 3 nearer the charge hopper 4 and these are somewhat narrower than the blades 16 as shown by comparing figures 7 and 4.

Moreover, the blades 20 are set at an angle closer to the perpendicularto the axis ofthe shaft, namely at 209 and these two factors allow successive blades 16 to be more closely spaced along the length of the shaft.

To assist in the positioning of the blades in any one of a plurality of predetermined inclinations, the tube 9 may be formed at one opening of each of the bores 10,11 with a plurality of slots 21 extending radially of the axis of the bore as shown in Fig. 9. A peg (not shown) projecting radially from the stem adjacent each blade locates in one or other of the slots to ensure the required inclination. It should be noted that the inclination of each blade may be varied independently ofthe others.

The inclination of any of the blades can be altered in situ by loosening its locking nut 12, and when worn any of the blades can be removed from the shaft 3 by removal ofthe nut 12.

In other embodiments, the angular spacing of successive blades in the spiral arrangement along the shaft may be other than 90 .

The shaft 3 is rotated by any type of prime mover (not shown) such as air, diesel, petrol, gas or electric- ity, the power input being dependent principally upon the blade configuration and tonnage throughout required per hour. Other variables that can increase or decrease the power input are: (a) revolutions per minute of the shaft (b) type of material and its condition (c) machine loading This range is in the order 1 to 1.5 H.P. per tonne of output per hour. Thus a 30 tonne capacity machine would require an input of from 20 H.P. to 45 H.P. The speed of rotation ofthe shaft can be varied to meet the needs of differing material and is normally in the range 300 to 750 r.p.m.The throughput of the drum is calculated to suit the particular site requirements but is generally calculated on the basis of between 10 and 30 tonnes per hour per square foot of cross sectional area of the barrel, this range being determined by the quality of the final material required which in turn is dependant upon blade angle setting and r.p.m.

In a typical installation the blades are spaced at 55 and 75 mm centres, but the spacing may be such that there are between 4 and 6 blades per linearfoot.

In another embodiment the stems 17 of the blades are finely threaded along their entire length and the bores 10, 11 are similarly threaded. This construction allows the projection of each blade towards the inner surface of the drum and its inclination to be adjusted.

Modifications to the machine as described may be incorporated. Thus, the charge hopper may be provided with a cut off valve. Sealed access panels and inlets for the introduction of further materials may be provided along the length of the drum 1. The drive to the shaft 3 may be provided with appropriate starting gear and emergency stop and relevant safety guards.

In use, the machine is always started in the empty or near empty state and run up to operating rotational speed before the introduction oftheparticu- late material to be treated. On shutting down, it should be run to empty before the rotation is stopped. However, the machine may be fitted with a hand crank to facilitate emptying if the desired operating conditions are for any reason not achieved. Alternatively, the machine can be cleared manually through maintenance access panels provided in the drum 1 for this purpose.

Claims (12)

1. A mchine for the treatment of particulate material comprising a drum having charge and discharge openings at its respective ends, a shaft rotatably mounted substantially horizontally on the longitudinal axis of the drum, a plurality of blades secured at spaced locations along the length of the shaft to project radiallytherefrom generally at different orientations about the axis of the shaft, with the plane of each blade inclined to the perpendicular to the shaft axis.

2. A machine according to Claim 1 wherein the angle of inclination of each blade is independently variable.

3. A machine according to Claim 1 or Claim 2 wherein the plane of the blade nearest to the discharge end of the drum is inclined to the perpendicular in the opposite sense to the inclination of the planes of others of the blades.

4. A machine according to any one of the preceding Claims wherein the blades apart from the one nearest to the discharge end of the drum form groups respectively nearer to and further from the discharge end of the drum, and the angle of incline tion of the plane of each ofthe blades of the group further from the discharge end of the drum is less than that of each of the blades of the group nearer; the discharge end.

5. A machine according to Claim 4 wherein the blades of the group nearer the discharge end are broader and spaced apart more widely than those of the group further from the discharge end.

6. A machine according to any of the preceding Claims wherein the orientation of radial projection of each blade relative to that of its neighbour or neigh bours is 90".

7. A machine according to Claim 6 wherein the drum is circular or polygonal in cross section.

8. A machine according to Claim 7 wherein the drum is constructed of or lined with material resistant to abrasion or chemical action.

9. A machine according to Claim 8 wherein the projection of the blades from the shaft is adjustable to vary the spacing of the blade from the inner surface of the drum.

10. A machine according to Claim 9 wherein the spacing is not less than 1.5mm.

11. A machine according to Claim 9, when used to treat material and the spacing is about twice the average particle size of the material.

12. A machine for the treatment of particulate material substantially as described with reference to the drawings.