Field of invention

The present invention relates to a method and apparatus for the extraction of at least one cemented carbide body from a component, especially but not exclusively to the extraction of at least one used cemented carbide body from a mining or construction component.

Background art

Cemented carbide bodies are widely used in components such as drilling tools, cutting tools, mining and machining tools and high wear resistant parts. However, when the cemented carbide bodies become too worn, they become ineffective and therefore the component is scrapped. The tungsten and cobalt in the cemented carbide bodies are both strategic rare metals and therefore there is significant value and an environmental benefit to being able to extract the cemented carbide bodies from the components. Cemented carbide scrap is considered an important secondary resource of cobalt and tungsten metals. Therefore, when these components are scrapped, they are collected and processed for recycling to recover the scrap cemented carbide so that is can be recycled to produce new components.

Known extraction methods, such as that disclosed in US4170513, involve the cemented carbide bodies being recovered from the worn components by using a sulphuric acid bath to eat away part of the steel surrounding the inserts, then heating the component in a furnace and then subsequently vibrating the heated component to knock out the inserts. There are, however, several problems with this type of process. The extraction time is long and not all the bodies are extracted, meaning that either the process needs to be repeated which adds further processing time and cost or the yield of the recovery is not as high as desired. A further issue is that the heated component needs to be manually moved from the furnace to the vibration device, which is a health and safety hazard. Therefore, it is desirable to find a new method for the extraction of cemented carbide bodies from components that is safer, quicker and results in higher extraction yields where up to all components can be cleaned out in one process and which does not involve manual handling of heated components.

Summary of the Invention

It is an objective of the present invention to provide a method and apparatus for extracting cemented carbide bodies from components that is safer, quicker, more environmentally friendly and results in higher extraction yields and apparatus for using in said method.

These objectives are achieved by providing, in a first aspect of the present application, a method for recovery at least one cemented carbide body from a component comprising the steps of: a) first clamping the component in a clamping device; and then b) simultaneously or cyclically heating and vibrating the component to dislodge the at least one cemented carbide body from the component.

Advantageously, by simultaneously or cyclically heating and vibrating the component, the at least one cemented carbide body is / are extracted is a much shorter time. Typically, the component will have a plurality of the cemented carbide bodies attached and using this method the yield of extraction of the bodies from the component is much higher, i.e. the output of recovered cemented carbide bodies per hour is increased. A further advantage of this method is that no manual handling of the heated components is required, therefore making the recovery process safer. This method works by locally heating the component in the region where the heating is needed for extraction of the cemented carbide bodies, therefore reducing energy input required compared to pre-heating the whole component in a furnace before vibrating the component. Further, this method is safer and required less manpower.

In one embodiment, induction heating is used to heat the component. Advantageously, induction heating enables the heating to be directed to the specific region(s) of the component where the cemented carbide bodies are attached. Therefore, minimising the energy input required and making this an energy efficient process.

Alternatively, flame heating is used to heat the component. Advantageously, flame heating is a very simple and cheap heating method to use.

In one embodiment, in step b) the component is heated to a temperature of between 600 - 1000 °C. Preferably to a temperature of between 700 - 900°. Advantageously, this temperature range enables the most efficient extraction of the cemented carbide inserts from the component without completely melting the steel of the component or using unnecessarily high energy. The temperature that the component is heated to can for example be measured using an IR gun. Different components may need different temperatures. Preferably, the component is heated to lowest temperature possible.

In one embodiment, there is an additional step, between steps a) and b) wherein the component is pre-heated before the simultaneously heating and vibrating of the component is performed. Advantageously, the addition of the pre-heat decreases the overall recovery time. Preferably, the pre-heat temperature is between 600 - 1000 °C, more preferably between 700 - 900°.

In one embodiment, induction heating is used to pre-heat the component. Advantageously, induction heating enables the heating to be directed to the specific region(s) of the component where the cemented carbide bodies are attached. Therefore, minimising the energy input required and making this an energy efficient process.

Alternatively, flame heating is used to pre-heat the component. Advantageously, flame heating is a very simple and cheap heating method to use.

Alternatively, furnace heating is used to pre-heat the component. In one embodiment, the vibration of the component is controlled by compressed air. Advantageously, this directs more force to the cemented carbide bodies, therefore meaning they are recovered from the component in the most time and energy efficient manner.

Alternatively, the vibration of the component is controlled by an electric motor or any other suitable means.

In one embodiment, the component is rotated in a radial and / or axial direction during step b). Therefore, the component is turned at the same time as being heated and vibrated. This may be particularly advantageous when the component comprises cemented carbide bodies that project in multiple direction, for example in the case of a rotary cone.

According to a second aspect of the present application there is an alternative method for recovery of at least one cemented carbide body from a component achieving the objectives descried hereinabove comprising the steps of: a) firstly, clamping the component in a clamping device; b) secondly, heating the at least one cemented carbide body using induction heating; and then c) thirdly, vibrating the component to dislodge the at least one cemented carbide body from the component.

Advantageously, using induction heating to heat the component enables the heating to be directed to the specific region(s) of the component where the cemented carbide bodies are attached. Therefore, minimising the energy input required and making this an energy and time efficient process that is more environmentally friendly and safer.

In one embodiment, in step b) the component is heated to a temperature of between 600 - 1000 °C. Preferably to a temperature of between 700 - 900°. In one embodiment, the vibration of the component is controlled by compressed air. In one embodiment, the component is rotated in a radial and / or axial direction during step b).

According to a third aspect of the present invention there is an apparatus for recovery of at least one cemented carbide body from a component having an axial axis comprising: a vibration device for vibrating the component in a direction having an angle of less than 30° with respect to the axial axis; a clamping device for positioning the component so that the cemented carbide bodies are vibrated in a direction having an angle of less than 30° with respect to the axial axis; and at least one heating device for heating of the component at the same time as vibrating the component.

Advantageously, this apparatus enables the component to be vibrated and heated simultaneously. Further, this set up means that component is restricted to only be able to vibrate and move in the most favourable directions, for example vertically, or in a direction having an angle of less than 30°.

In one embodiment, the clamping device comprises a plate having a drop-shaped opening; Advantageously, this enables a large range of component sizes and shapes to be held using the same clamping device. The design of the clamping device minimizes the movement of the component relative to the clamping device. Further, this clamping device enables the centre point of the component relative to the heater to remain the relatively unchanged, even if different sized components are clamped, which means that advantageously, the heating device does not need to be repositioned when different sized components are treated, which saved processing time.

In one embodiment, the clamping device comprises a threaded component. Advantageously, this provides a secure clamping for keeping the component in the required position.

In one embodiment, the vibration device is a compressed air-controlled vibrating device. Advantageously, this directs more force to the cemented carbide bodies, therefore meaning they are recovered from the component in the most time and energy efficient manner.

In one embodiment, the apparatus further comprises a vertical block and at least one guiding rod positioned between the vibration device and the clamping device. Advantageously, this directs the vibrations in a vertical direction with respect to the axial axis. In one embodiment, the heating device is an induction heater, otherwise known as a high- frequency heater. Advantageously, the induction heating device can be positioned where required to locally heat the component at the correct position to remove the cemented carbide bodies in the most time and energy efficient manner. Further, induction heating devices do not spread any heat up into the vibration device, all the heat can be directed to the component.

A specific implementation of the present invention will now be described, by way of example only, and with reference to the accompanying drawings in which:

Figure l is a schematic drawing of the apparatus.

Figure 2 is a schematic drawing of a preferred embodiment of the clamping device.

Figure 1 shows a schematic drawing of the apparatus 8 for recovery of at least one cemented carbide body 2 from a component 4 having an axial axis 40. The apparatus 8 comprises a vibration device 10 for vibrating the component 4 in a direction having an angle of less than 30°, preferably less than 20°, with respect to the axial axis 40 in any rotational direction, more preferably vertically with respect to the axial axis 40; a clamping device 6, otherwise known as a fixture, for positioning the component 4 so that the at least one cemented carbide body 2 is vibrated in a direction having an angle of less than 30°, preferably less than 20° with respect to the axial axis 40 in any rotational direction, more preferably vertically with respect to the axial axis 40; and at least one heating device 12 for heating of the component 4 simultaneously or cyclically with vibrating the component 4. The clamping device 6 is typically made of steel and is fixed to a frame 36 and is suitable for clamping either cold or pre-heated components 4. The clamping device 6 could also be moveable, so that the component 4 can be rotated as required, the rotation could be controlled using a programmable rotator. Preferably, the vibration device 10 is a compressed air-controlled vibration device 10. The pressure and the flow rate of the compressed air can be controlled to optimise the vibrations so that the energy is directed to removal of the at least one cemented carbide body 2. Preferably, PLC controlled valves are used to optimise the vibration.

Alternatively, the vibration device 10 could be controlled using an electric motor or any via any other suitable means. Alternatively, the vibration device 10 is an electric motor or any other suitable vibrating device.

The cleaning process to extract the inserts is made by vibrating the clamping device 6 and the component 4 in a vibrating movement controlled in force and speed by the vibrating device 10 in a steered and controlled pulsed process.

Preferably, the vibration device 10 is attached to the clamping device 6, so that the vibration of the component 4 is done via the clamping device 6. Alternatively, the vibration device 10 could be connected directly to the component 4 so that the vibration of the component 4 is done directly to the component 4.

Optionally, there is at least one vertical block 26 and at least one guiding rod 28 positioned between the vibration device 10 and the clamping device 6. Typically, the vertical block is made from steel or aluminium, but it could be made from any other suitable material that is capable of directing the vibrations in the preferred direction.

Optionally, a damping element 38, such as disc springs or rubber dampeners may be positioned axially between the vibration device 10 and the at least one vertical block 26 to reduce the impact of the vibrations on the frame 36.

Preferably, the heating device 12 is an induction heater, otherwise known as a high- frequency heater. Induction heating is the process of heating an electrically conducting object by electromagnetic induction, through heat generated in the object by eddy currents. An induction heater consists of an electromagnet and an electronic oscillator that passes a high-frequency alternating current (AC) through the electromagnet. The rapidly alternating magnetic field penetrates the object, generating electric currents inside the conductor, called eddy currents. The eddy currents flowing through the resistance of the material heat it by Joule heating.

The heating device 12 is moveable in both vertical and horizontal directions, either manually or automatically.

The induction heater typically has a circular or U-shaped coil, but the coil could be moulded to any other suitable shape or size to suit the geometry of the component 4 being treated. Typically, the induction heater comprises a single coil, but multiple coils could also be used. The heating device 12 is preferably held in position using a heating device holder 14. The heating device holder 14 could be moveable, either manually or automatically to be able to position the heating device 12 at the correct location relative to the component 4 so that the optimal distance between the heating device 12 and component 4 is achieved, i.e. as close as possible to be able to achieve most efficient heating without resulting short circuiting. Alternatively, the heating device 12 could be held in position by hand.

Alternatively, the heating device 12 could be a flame heater, which could either be positioned by hand or using a heating device holder 14. For example, an acetylene and compressed air flame heater could be used, this type of flame heater produces flames that are hot enough to sufficiently heat the component 4 to the required temperature, but not so hot that the steel from the component 4 will melt, which could make the extraction of the cemented carbide 2 inserts more difficult, but any other sort of flame heater could be used. Alternatively, a combination of induction heating and flame heating could be used.

A safety cage (not shown) can be installed to guide the at least one hot extracted cemented carbide body 2 into a funnel (not shown) and down into a collection box (not shown), which could be insulated.

Figure 2 shows a preferred embodiment of the clamping device 6 wherein the clamping device 6 comprising a plate 16 having a drop shaped opening 18; a threaded component 42, which in this case is a nut 20 welded onto the plate 16 for receiving a tightening bolt 22; and wherein the tightening bolt 22 comprises a hardened centre pin 24 for pressing into the component to hold it securely in place. The hardened centre pin 24 can rotate freely around when forces from the tightening bolt 22 is applied. An alternative design for the threaded component 42 or any other suitable non-threaded clamping device 6 e.g. a levered device could also be used.

It is preferably for the heat input into the clamping device 6 to be kept to a minimum. Therefore, the clamping device 6 could be water cooled.

The method for recovery of at least one cemented carbide body 2 from a component 4 comprising the steps of: a) clamping the component 4 in a clamping device 6. Then b) simultaneously or cyclically heating and vibrating the component 4 to dislodge the at least one cemented carbide body 2 from the component 4.

In one embodiment, the heating and vibrating could either be done simultaneously. In another embodiment the heating and vibrating could be done cyclically. By cyclically it is meant that component 4 is first heated to a target temperature range, specific to that component 4, then the heating may be paused and then immediately or quickly afterwards, such as less than a minute, the vibrating started, then the vibrating paused and then immediately or quickly afterwards, such as less than a minute, the heating started again etc, with the cycle being repeated until all the cemented carbide bodies 2 have been recovered. Alternatively, a combination of simultaneous and cyclic heating and vibrating could be used. The at least one carbide body 2 could be, be is not limited to, a mining insert, a cutting pick or a blade shape carbide unit, but is could be any other carbide body 2 attached to a component 4.

The component 4 is typically a mining or construction component and for example could be a top hammer drill bit or leg, a down the hole (DTH) drill bit or leg, a cone bit, a cutting pick, a raise boring shell, a rotary drill cone or leg, a horizontal direction drill (HDD) bit or leg, or reamer block leg but could be any other component 4 with at least one cemented carbide body 2 attached to it. The component 4 is typically made from steel and once all the cemented carbide bodies 2 have been removed, the steel from the component 4 could also be recycled.

The recovery method can be used for components 4 where the at least one cemented carbide insert 2 was pressed or brazed in position or held in any other way.

Typically, this recovery process would be used to recover at least one cemented carbide body 2 from used components 4, in this case they are commonly referred to as dull components 4. However, if required this method could also be used to remove at least one cemented carbide body 2 from an unused, new component 4.

The component 4 is vibrated in a vertical direction with respect to the axial axis 40, and the component is clamped in position so that the cemented carbide bodies 2 are facing downwards. For components 2 where the cemented carbide bodies 2 are positioned in multiple directions, for example rotary or HDD cones, it may be necessary to rotate the component 4 so that all the cemented carbides bodies 2 are at some point positioned downwards.

Typically, in step b) the component 4 is heated to a temperature of between 600 - 1000 °C, more preferably to a temperature of between 700 - 900 °C. The component 4 can continue to be heated until all of the cemented carbide bodies 2 have been recovered.

The relative position of the component 4 to the heating device 12 can be altered during the operation to heat different areas of the component 4 as necessary in order to optimise the rate of recovery of the at least one cemented carbide body 2 from the component 4. When induction heating is used the coil should be positioned as close to the component 4 as possible to achieve the most efficient heating so than minimal heat input is needed with the quickest extraction time, but not so close that contact is made and short circuited. The size and shape of the coil should be selected to maximise the efficiency of the heating.

A programmable rotating device could be used so that the rotation is pre-programmed to be conducted to suit the geometry of the specific component being processed. Optionally, there is an additional step, between steps a) and b) wherein the component 4 is pre-heated. If a pre-heating step is included, this could be done either with the cemented carbide bodies 2 facing downwards or upwards, i.e. in the same position as in step b) or inverted. The pre-heating step us preferably done using induction heating, but could also be done using flame heating, or in a furnace. It is also possible for a combination of induction heating, flame heating and furnace heating to be used for the pre-heat if required. If pre-heating is used the component 4 would typically be heated to 600 - 1000 °C, preferably 700 - 900°C.

The recovered at least one cemented carbide body 2 could then be collected and allowed to fall into the collection box (not shown), where they are left to cool. Once all the cemented carbide bodies 2 have been removed the component 4 is moved to a release position, from which the component 4 is dropped to be cooled.

Alternatively, the method for recovery of at least one cemented carbide body 2 from a component 4 comprises the steps of: firstly, clamping the component in a clamping device 6; secondly, heating the at least one cemented carbide body 2 using induction heating; and then thirdly, vibrating the component 4 to dislodge the at least one cemented carbide body 2 from the component 4.

It is also possible with any of the methods described herein to set the apparatus 8 up so that at least one cemented carbide body 4 can be removed from multiple components 4 as the same time. For example, a plurality of components 4 could be fixed, e.g. by welding, to a plate for processing all at one time.