Bulk granular materials such as mineral concentrates, sludge residues, milled, crushed or ground substances and the like can be difficult to discharge from containers as the bulk material tends to settle in the container especially if there is moisture present in the. bulk material. This is particularly so when the bulk granular material includes very fine material with particle sizes in the order of 10-50 microns which tends to adhere to the container walls. To overcome this problem it is known to provide augers or the like in hoppers or bins to discharge the material. When the container is a wagon body on a truck or trailer, the problem is exacerbated by transport as the vibration set up in the wagon body during transport tends to settle and compact the material within the wagon. So, when it comes to discharging the material, such as by tipping the wagon, for example, the material is resistant to discharge and bridging of material tends to occur between the base and side walls of the wagon body around the edges of the base of the wagon body. This means that the load carried by the wagon is effectively reduced with increased transport costs due to the"ballast"material retained in the wagon. Cleaning is often difficult, time consuming and expensive. It will also be noted that, in some cases, the bulk granular material transported may corrode or otherwise chemically attack the material of which the wagon is constructed which typically is of steel or aluminium material, thus increasing the problems of bridging and discharge difficulties.

Because of the tendency of bulk granular material to stick or clump to itself and to the sides of the wagon, the wagon generally has to be tilted to a relatively high angle for material discharge to commence and to complete discharge of as much of the granular material as possible from the wagon. Even when fully tilted it may be necessary to aid discharge of granular material by for example jogging the wagon by either movement of the tipping ram or of the vehicle itself by for example reversing the vehicle against a bump stop. Such jogging puts considerable strain on the tipping ram and/or the vehicle chassis which may be damaged as a result.

Further, the relatively high tipping angle and the jogging of the wagon poses stability problems for the vehicle.

In addition, because of the granular materials'inherent resistance to flow and the tendency of the granular material to adhere to the sides of the wagon, relatively long tipping times are required to discharge the granular material from the wagon. This is particularly so if it is necessary to aid discharge by jogging the wagon as described above. This reduces efficiency and increases the transportation costs.

The present invention is directed towards overcoming these problems.

According to the invention there is provided apparatus for handling bulk granular material, said apparatus having a contact surface with which the granular material comes into contact during use of the apparatus, characterised in that said contact surface is coated with a smooth epoxide polymer based non-stick lining material.

Preferably the coating of lining material has a thickness in the range 3-10 microns.

According to one aspect of the invention there is provided a tipping wagon for bulk granular materials comprising a body having a base and upstanding side walls around the base forming with the base a container for reception of material to be carried in the wagon, the body having a discharge door, the wagon being for pivotally mounting on a support frame having means for tilting the wagon on the support frame for discharge of material through the discharge door, at least an upper face of the base being coated with a smooth plastics lining material. Preferably, the lining comprises an epoxide polymer based material which provides an interior of the wagon with a smooth low friction surface for facilitating flow of bulk granular material being discharged from the body. Conveniently also the polymer also provides corrosion and chemical resistance.

Particularly suitable lining materials comprise advanced polymer coatings"IPI- SUPERBARRIER"and"IPI-VESSEL LINING" (Registered Trade Marks) manufactured by the US company, Integrated Polymer Industries, Inc. of California, U. S. A.

It will be appreciated that one or both of the above-mentioned lining materials may be used to cover some or all of the interior surface of the body. For example, a coating of "IPI-SUPERBARRIER"polymer may be provided on the base of the body and extending partially up the side walls, typically 300-500mm for mineral ore concentrates, essentially covering the base and portions of the side walls with which the bulk granular material is likely to be in direct contact during carriage and discharge. Conveniently, the remainder of the interior of the wagon may be covered in the"IPI-VESSEL LINING"polymer to provide corrosion resistance and protection to the wagon.

Conveniently the polymer materials have a low coefficient of friction providing a smooth surface so that the bulk granular material will slide easily from the wagon for discharge when the wagon is tipped. The bulk granular material is less likely to cling to the sides of the wagon so that a substantially full discharge of bulk granular materials from the wagon can be achieved.

It will be appreciated that the lining materials in addition to providing a non-stick surface on the wagon interior provide an anti-corrosion barrier which is water and chemical resistant. Further, advantageously the polymer materials are relatively tough providing good wear and abrasion resistance and have a minimum maintenance long life.

In a particularly preferred embodiment, the invention provides a wagon comprising a body having a base and upstanding side walls around the base forming with the base an open-topped container for reception of material to be carried in the wagon, a material filling opening being defined by upper ends of the side walls, a rigid cover mounted on the side walls, the cover being movable between a closed position across the filling opening and an open position for filling the container body, and sealing rneans engagable between the cover and the side walls when the cover is in a closed position to seal an interior of the body, the lining material covering at least the base and preferably also portion of the side walls extending upwardly from the base.

In a further embodiment a locking beam is engagable with a lower end of the discharge door to securely retain the discharge door in a closed position, the beam

being carried on pivoting support arms on the chassis which are pivotally movable between a locking position against the door and a released position allowing the door to open for discharge.

In another aspect, the invention provides use of the above-mentioned advanced polymer coatings for coating bulk granular material contacting surfaces of containers such as wagons and other materials handling apparatus used for the transport and handling of bulk granular materials.

The invention will be more clearly understood by the following description of some embodiments thereof, given by way of example only, with reference to the accompanying drawings, in which:- Fig. 1 is a perspective view of a tipping wagon according to the invention; Fig. 2 is a sectional elevational view of the wagon; and Fig. 3 is a view similar to Fig. 2 showing a cover of the wagon in an open position.

Referring to the drawings, there is illustrated a wagon according to the invention, indicated generally by the reference numeral 1. The wagon 1 is mounted on a chassis 2 having wheels 3. The wagon 1 has a box-shaped material container body 4 mounted on the chassis 2 and comprises a base 5 with upstanding side walls comprising sides 6,7, a front wall 8 and a rear discharge door 9 which is hingedly mounted at its upper ends between the sides 6,7. A cover 10 is hingedly mounted on one side 7 for movement between an open position as shown in Fig. 2 and a closed position as shown in Fig. 3. A multi-stage wagon tilting ram 13 is mounted between a front end of the body 4 and the chassis 2.

The cover 10 is mounted on the side wall 7 by hinges 11. Rams 12 are mounted between the side wall 7 and the cover 10 and are operable to pivot the cover 10 on the side wall 7 for opening and closing the cover 10. Each ram 12 is connected to an hydraulic power supply for operation of the rams 12.

Locking means is provided for locking the cover 10 in the closed position. In this case, the locking means comprises locking bolts 15, carried by rams 16 which are mounted on an underside of the cover 10. The rams 16 are operable to extend the bolts 15 for engagement with associated receiver sockets (not shown) adjacent an upper end of the side wall 6 for securely locking the cover 10 in the closed position.

Additionally, further locking means is provided in the form of manually operated screw locks 18 which extend through hollow pillars 19 in the side wall 6 for engagement with associated receiver slots 20 in the cover 10. Instead of the screw locks 18 ratchet straps may be provided engagable between the cover and the body.

A resilient seal is engagable between the cover 10 and the side walls 6,7,8,9. The seal may be mounted along an upper edge of the side wall 6,7,8,9 and/or around a peripheral edge of an inside face of the cover 10. Advantageously, the seal prevents ingress of water and moisture which could adversely affect a cargo and also prevents the escape of dust, fumes and odours from an interior of the container during transport of material in the container.

A rear discharge door 9 is hinged at its upper end to the sides 6,7 of the container body 4. A five point door locking clamp is mounted at the bottom of the door and a manual twist lock clamp is mounted on each side of the door 9. For added security, a locking beam 28 is engagable with a lower end of the door 9 to securely retain the door 9 in the closed position. The beam 28 is carried on a pair of pivoting support arms 29 which are pivotally movable by means of rams to release the door for discharge.

A lining 30 of the advanced polymer coating"IPI-SUPERBARRIER"is provided on an inner surface of the base 5 and extending partially up the side walls 6,7,8 and the door 9. The remaining interior faces of the walls and cover are coated with a lining 31 of the advanced polymer coating"IPI-VESSEL LINING".

It will be appreciated that the polymer coatings are particularly suitable for use in road transport as the lining is sufficiently flexible to accommodate bending of the base of the wagon during transport. It is however important that the lining should not be too

thick or it will crack due to the flexing of the base. It has been found that a lining coating having a thickness in the order of 4-6 microns gives good results in this regard. Care must be taken when applying the polymer coating to the surfaces of the wagon. Preferably the surfaces should be cleaned by abrasive blasting. In this regard sand blasting has been found to be preferable to shot blasting. If the indentations caused by the shot are too deep, say in the order of 0.25mm, the lining has a tendency to crack as the correct coat thickness is difficult to achieve. The"IPI- SUPERBARRIER"and"IPI-VESSEL LINING"polymers comprise an epoxide polymer base which is combined with a polyamine solidifier prior to application to the pre- treated surfaces. It is important to control the temperature and humidity during application and curing of the lining material on the wagon surfaces for optimum results.

The above mentioned polymer coatings are sufficiently hard to provide good abrasion resistance when the bulk granular material is sliding out of the wagon on discharge. It is envisaged that it may be possible to modify the hardness of the polymers to provide increased resilience and flexibility if required or indeed to increase the hardness for greater abrasion resistance if required.

It will be appreciated that the provision of the polymer lining greatly increases the performance of the wagon. Due to the smoothness of the polymer surface substantially all the bulk granular material will be discharged sliding easily from the wagon. There is no need for jogging of the wagon to release the bulk granular material. Tipping time is reduced due to the ease with which the bulk granular material will slide from the wagon. Further, the bulk granular material will commence sliding from the wagon when the wagon is tilted at an angle of 350 with full discharge occurring at about 42o tilt angle. For a non-coated wagon the slide angle is typically 33-39o with full discharge occurring at about 46D. Thus the stability of the wagon is considerably improved during use.

While in the embodiment described above the lining is shown applied to a road transport wagon it is envisaged that the polymer lining may be advantageously used other materials handling applications for coating surfaces in for example loading, shovels, conveyors, hoppers, silos, bins, trailers and containers including lift on/lift off

containers as used in tipping applications, for coating those surfaces of the apparatus which come into contact with the bulk granular material to prevent the bulk granular material adhering to said surfaces and causing the bridging problems as previously described.

The invention is not limited to the embodiments hereinbefore described which may be varied in both construction and detail.