GB2613657A

GB2613657A - Adjustable homogenizer impact head

Info

Publication number: GB2613657A
Application number: GB2201231.4A
Authority: GB
Inventors: Edwards Michael
Original assignee: Blackswan Graphene Inc
Current assignee: Blackswan Graphene Inc
Priority date: 2021-12-13
Filing date: 2022-01-31
Publication date: 2023-06-14
Also published as: GB202202468D0; GB202118020D0; WO2023108265A1; GB2613661A; GB2613651A; GB202201231D0

Abstract

A homogenizer comprising an impact head, a housing 10, 10’ surrounding the impact head in a manner to form a gap between the impact head and the housing through which a fluid may flow, wherein the impact head comprises a sloped impact head 40 with a sloped geometry. The sloped impact head may be conical, pyramidal, frustro-conical or frustro-pyramidal. The impact head may comprise a pneumatic mechanism to move the impact head within the housing. The impact head may be configured to rotate within the housing and to rotate freely or driven to rotate at specific intervals. The impact head may be formed from a tough material including tungsten carbide, zirconia, silicon nitride, alumina silicon carbide, boron nitride or diamond.

Description

Adjustable homogenizer impact head

Background

Graphene is a two-dimensional allotrope of carbon, consisting of sheets of a few atoms thickness in a hexagonal structure. Graphite, the widely used mineral is effectively a crystalline form of graphene, in which layers of graphene are bound together by van der Waals forces. Graphene has attracted considerable interest since its discovery as an isolatable material in 2004. The novel mechanical, thermal and electrical properties of the material suggest a number of uses. Graphene can be produced on a laboratory scale sufficient for experimental analysis, but production in commercial quantities is still a developing area. Other single layered structures such as boron nitride are expected to exhibit similarly interesting properties in the nanotechnology field.

A review of this technology has been compiled by Min Yi and Zhigang Shen and their titled 'A review on mechanical exfoliation for the scalable production of graphene', Journal of Materials Chemistry, A, 2015, 3, 11700 provides an overview of the state of the art regarding graphene production. Bottom-up techniques, such as chemical vapor deposition and epitaxial growth, can yield high-quality graphene with a small number of defects. The resultant graphene is a good candidate for electronic devices. However, these thin-film growth techniques suffer from a limited scale and complex and hence expensive production, and cannot meet the requirements of producing industrially relevant quantities of graphene.

Large-scale production of graphene at a low cost has been demonstrated using top-down techniques, whereby graphene is produced through the direct exfoliation of graphite, sometimes suspended in a liquid phase. The starting material for this is three-dimensional graphite, which is separated by mechanical and/or chemical means to reveal graphene sheets a few atoms thick.

The original technique used by the discoverers of graphene, the "Scotch Tape" method can be used to prepare high-quality and large-area graphene flakes. This technique uses adhesive tape to pull successive layers from a sample of graphite. Based on the graphene samples prepared by this method, many outstanding properties of graphene have been discovered.

However, this method is extremely labor-intensive and time consuming. It is limited to laboratory research and seems unfeasible to scale up for industrial production.

The three-roll mill technique is a method to scale up the Scotch Tape method, using polyvinyl chloride (PVC) dissolved in dioctylphthalate (DOP) as the adhesive on moving rolls which can provide continuous exfoliation. Though the three-roll mill machine is a known industrial technique, the complete removal of residual PVC and DOP to obtain graphene is not easy and brings about additional complexity.

Prof. Jonathan Coleman's group at Trinity College Dublin have developed a high-yield production of graphene by the sonicafion assisted liquid-phase exfoliation of graphite in 2008.

Starting with graphite powder dispersed in specific organic solvents, followed by sonication and centrifugation, they obtained a graphene dispersion. This method of producing graphene is capable of scaling up but one shortcoming is the extremely low graphene concentration (around 0.01 mg/mL) of the suspension produced, which is not necessarily suitable for bulk production.

Additionally, ultrasonic processors can only achieve the high-power density required in small volumes, so it is difficult to scale up this process to achieve any economy of scale. A relevant disclosure can be found in W02013101021 1A1.

Another technique that can produce a high yield while not being as labor intensive, or energy consuming, as the methods describe above, would be the use of shear force techniques. As is well known, graphite layers have a low resistance to shear force which makes graphite a useful lubricant. This has been exploited in a number of techniques which apply shear force to exfoliate graphene from graphite.

Ball milling, a common technique in the powder industry, is a method of generating shear force. A secondary effect is the collisions or vertical impacts by the balls during rolling actions 20 which can fragment graphene flakes into smaller ones, and sometimes even destroy the crystalline nature of structures.

Several improvements to the ball milling technique have been attempted, such as wet ball milling with the addition of solvents, but these techniques still require a very long processing time (around 30 hours) and produce a high number of defects even if suitable for industrial scale, bulk, production. A relevant disclosure can be found in WO 2012117251 Al.

Some shear force production techniques have used an ion intercalation step prior to applying the shear force to weaken the inter-layer bonds. This reduces the energy required to exfoliate the graphite into graphene, but the resulting graphene may be contaminated with residual ions contaminating the finished product, and the process requires additional time and cost which reduces the industrial application of this technique.

More recently fluid dynamics-based methods have emerged for graphite exfoliation. These are based on mixing graphite in a powder or flake form with a fluid to form a suspension, the fluid can then be subjected to turbulent or viscous forces which apply shear stress to the suspended particles. Usually, the fluid is either a liquid of the type often used as a solvent and may include a surfactant mixture tailored to the removable from the finished product.

One method of generating the shear forces is with a high shear, for example rotary mixer. Graphene exfoliation has been demonstrated using a kitchen blender to create shear forces on graphite particles in suspension. This process has been scaled up using commercial high shear mixers comprising rotating blades passing in close proximity to an aperture screen to produce high shear. The graphite particles experience a shear force applied by the fluid due to the difference in velocity of the mixing blades and the static shear screen. A relevant disclosure can be found in VV02012/028724A1 and WO 2014/140324 Al.

A further method is the use of a high-pressure homogenizer with a micro fluidizer. The micro fluidizer in this case consists of a channel with a microscale dimension, meaning of around 75pm. Fluid is forced through the channel from an inlet to an outlet using high pressure. Because of the narrow dimension of the channel, there is a high shear force generated by viscous friction between the walls and the book flow which leads to delamination of the graphite. This method requires very high pressures and the starting graphite must already have been comminuted into the micron size range. A relevant disclosure can be found in W02015/099457.

There exists a need for a graphene production process that can produce graphene using less energy, that can be scaled up to high rates of production without loss of quality of the finished product. Such a process using a preprepared graphite solution, and a homogenizer valve is disclosed within WO 2021/198794, which discloses using areas of high and low pressure within the valve to apply force to the solution, which in turn can break down the graphite in the solution other useful products such as graphene.

Another method using such a homogenize, for produce graphene, can be found in W02018/069722, which discloses an apparatus wherein a pump is used to pump a graphite solution through a fluid conduit, at the end of the conduit the fluid flow is targeted towards the center of a symmetrical impact head, to provide the shear force. wherein the impact head is symmetrical around the axis parallel to the fluid flow. Wherein the impact head can be rotated around the axis of symmetry, so as to reduce the risk of localized wear around the area of impact, thereby extending the operational life-span of the impact head.

Further in this apparatus the impact head may be attached to an adjustable member, so that the position of the impact head by be adjusted to along its longitudinal axis, thereby changing the size of the gap between the conduit and the impact head. In these cases, the gap size is adjusted to clear any blockages that form between the conduit and the impact head. In some embodiments the impact head may be attached to a pressure drop valve. Wherein the valve is used to provide a predetermined amount of backpressure from the conduit and other components, to improve the efficiency of the homogenizer.

In some embodiments of the apparatus the impact head is comprised of a hardened material, or at least the surface upon which the fluid impacts are covered in a layer of such a material.

These hardened materials are chosen so as to reduce the risk of wear to the impact head's surface, and possible to increase the amount of shear force between the fluid and the impact head. Suitable materials that could be used include material(s) selected from the group tungsten carbide, zirconia, silicon nitride, alumina, silicon carbide, cubic or wurtzite boron nitride and diamond.

The apparatus may also include an impact head surround, positioned around the impact head, or the outlet of the fluid conduit, which extends the region in which the fluid is constrained before exiting the apparatus, to try and further homogenize the fluid solution as it exits the apparatus, thereby improving the apparatus' efficiently and yield.

Such an apparatus is disclosed in UK patent application GB15181.5. That apparatus provides a fluid conduit for impacting a suspension of particles to be de-laminated against an impact head having an impact face and an annular gap. In practice it is been found that the apparatus has a limited lifespan before maintenance is required as the annular gap can either become clogged with particulate material and/or become worn so as to provide an uneven gap through which suspension preferentially flows and, which results in the gap becoming larger, reducing the homogenizers effect as the fluid pressure drops within the apparatus. Such clogging tends to occur when fresh portions of the impact head, or the surrounding annular surface are exposed, as the reduced homogenization due to the wear will leave larger particles in the solution, as well as the particles of debris from the worn areas.

The present invention seeks to overcome the problems in previous techniques to provide a production method for graphene that is rapid, scalable to industrial quantities and energy efficient, via the above-mentioned homogenizer method. But such a method still has some problems as described above, this application predominantly addresses the question of increasing the yield of a conventional impact head, and the problem of clogging, while not reducing the effectiveness of the homogenizer's shear force technique.

Summary

The present invention discloses a homogenizer. Said homogenizer comprises an impact head and a housing surrounding the impact head. Where in the housing is shaped in a manner as to form a gap between the impact head and the housing through which the fluid being processed by the homogenizer may flow. The impact head used in the claimed homogenizer uses a specific geometry to help improve the efficiency/effectiveness of the homogenizer, specifically the claimed impact head comprises a sloped impact head, with a sloped geometry.

The present invention provides a homogenizer designed to process fluids and aqueous suspended materials to produce graphene, or other atomic scale materials. Preferable these atomic scale materials would comprise laminar materials, examples of such materials include graphene, and graphene nanoplatelets (GNP). Wherein the homogenizer uses shear force technique on a fluid or mixture being processed to produce the desired material, for example a fluid containing aqueous suspended graphite may be processed to form graphene, while a fluid containing suspended GNP stacks may be processed to produce smaller stacks, fore example process that form GNP usually have stacks of 10-50 platelets, a homogenizer may be used to reduce the size of these stacks to a more desirable size with fewer layers, namely less than 20. In the homogenizer the mixture is injected into the apparatus at a relatively high pressure/flow rate, that then impacts upon the impact head, using the shear force of this collision to separate the materials within the mixture to form the desired atomic scale material.

Examples of currently used homogenizers, that may utilize the claimed impact head and housing, include the Ariete line homogenizers produced by GEA mechanical Equipment Italia. Such homogenizers come in different sizes based on the intended purpose, for example the Ariete 3006 is designed for small scale processes, while the Ariete 5400 is larger being designed to work on bulk materials which require higher processing rate to produce sufficient yield. Regardless of the size of the homogenizer, the above-mentioned process would still work the same, it is just a case that the larger homogenizers may require a plurality of impact head, or at least more than the smaller scale homogenizers. It should also be noted that these homogenizers can be utilizer in an array of different processes, such as; producing carbonated, and/or alcoholic beverages, by using the homogenizers to fuse different compound into the beverage, producing ready-to-drink teas and coffees, producing emulsions, such as milk of paint. And producing solid, semi-solid and liquid components to be used in a range of pharmaceuticals, which may include fusing components to form creams or gels, or mixing a variety of liquid components to form a desired mixture.

In a conventional impact head designed for this purpose, the fluid flow of the mixture will flow through an apparatus wherein the flow will directly impact the impact surface of an impact head, generating the shear force needed to generate the desired homogenizing reaction. After this impact, the fluid flows across the surface of the impact head wherein it may impact the sides of the impact heads housing, these secondary impacts may also provide enough force to further homogenize the mixture. Then the fluid will flow through a gap, positioned between the impact head and the surrounding housing. Wherein the fluid will continue through the rest of the apparatus, and may undergo further impacts, either with other components or by having the flow redirected towards the impact head.

It is noted that as the fluid flows through the gap between the impact head and the surrounding housing, the fluid may experience additional shear force, due to in changes in pressure as the fluid enters and exits the gap, and from the friction with the walls of said gap. This additional force on the fluid may allow further homogenizing reactions to occur, this in turn may increase the overall yield of the homogenization reaction. In some cases, the size and shape of the gap may be altered in order to produce a desired pressure, or force, on the fluid within the gap. Though it may also prove beneficial to change the shape and size of the impact head, and/or the surrounding housing, to increase the amount of force, or pressure, applied to the fluid as it flows through the homogenizer, to further increase the yield of the homogenizing process.

As previously mentioned, over time the impact head of the homogenizer can become worn, when this occurs the debris from the worn impact head may be carried away by the fluid flow. Wherein this debris may begin to build within the gap surrounding the impact head, until the gap becomes completely blocks. In some cases, the worn impact head may reduce the efficiency of homogenization reaction, as a result the mixture in the fluid flow may comprise larger particles which may also clot, or form deposits, that may eventually block the gap around the impact head. Currently to counteract this the homogenizer process would need to be routinely stopped to replace the impact head and manually clear any blockages. It is noted that for maximum yield a homogenizer process should be continuous, so such pauses will affect the overall yield of the process. And though routine maintenance will always be necessary, there is a need for a homogenizer that requires fewer pauses in the process, and preferably provides a means to remove blockages without stopping the process.

Drawing Figure 1: depicts an example flat impact head with pneumatic adjustments mechanism. Figure 2: depicts a sloped impact head with pneumatic adjustments mechanism.

Figure 3: depicts a flat impact head, with a sloped housing and pneumatic adjustments mechanism.

Figure 4: depicts a sloped impact head, with a sloped housing and pneumatic adjustments mechanism.

Figure 5A: depicts a frustro-conical impact head within a sloped housing, wherein the slope of the walls and the impact head are parallel.

Figure 5B: depicts a frustro-conical impact head within a sloped housing, wherein the slope of the walls and the impact head are not parallel.

Figure 6: depicts a conical impact head with a domed tip/point, with a sloped housing. Figure 7: depicts an example impact head with a frustro-pyramidal geometry.

Detailed Description

The claimed invention provides an improved impact head for a homogeniser, specifically a homogeniser used to form atomic scale materials, preferably laminar materials, such as graphene. Wherein these materials are produced by using the homogeniser to process a fluid mixture, or aqueous suspendered materials in a mixture, such as an aqueous suspension of graphite, or particles of graphite, hexagonal boron nitride or molybdenum disulphide. The materials produced by these homogenizers may then be placed back into the homogenizer for further processing, to further increase the yield, or to produce a different reaction, or may be further processed to form useful materials, such as using the produced graphene to form carbon nanotube, or graphene nanotubes. The disclosed impact head is designed to help increase the yield of the homogenisation process, by providing impact heads with an improved geometry to increase the yield of the homogeniser process, and may also provide a means of adjusting the size, or shape of the gaps surrounding the impact head to further increase the yield of the process. For changing this gap can help increase the amount of pressure, shear force, and/or frictional force exerted on the fluid as it exits the impact head housing. In doing this the impact head geometry may increase the probability of a successful homogenisation reaction occurring within the fluid, which in turn will increase the efficiency of the homogeniser process. Additionally, the claimed impact head is design to provide a means for removing blockages formed within the gap between the impact head and the impact head's housing. It should be noted that in most cases the term 'improve yield' would refer to increasing the amount of the desired product being produced, but in some cases to improve the yield of the homogenizer process involves improving the quality of the product produce, rather than the quantity. For example, when producing GNP, the platelets form into layers, or stacks, and in many applications, it is preferable for these stacks to have fewer layers, therefore a mixture of GNP may be processed by the homogeniser to break down the stacks into small stacks, thereby improving the yield of high-quality GNP, despite the fact the number of platelets remains the same overall.

In the claimed invention the preferred geometry for the impacted head is a sloped, or angled, shape. These geometries include shapes such as cones, frustro conical geometries, pyramids, and frustro pyramid geometries. The important feature of these geometries is that they provide a slope, or incline, between the base of the impact head and the top surface of the impact head. For in use the narrower end, or point in the case of a cone or pyramid, of the geometry is positioned as the top surface, so that it may be used as the impact surface, meaning this surface, or point, is facing towards the fluid flow, and will be the point the fluid initially impacts within the homogeniser. After the initial impact the fluid will flow down the slopped surfaces, until them impact the housing surrounding the impact head, these secondary impacts may produce further homogenising reactions. Then the fluid may continue to flow into a gap between the impact head and the surrounding housing. It is noted that the sloped surface of the impact head ensures that the gap surrounding the impacted is shaped so that the channel formed becomes narrower as the fluid flows away from the impact surface, a combination of the fluid accelerating as it flows down the impact head slope and the pressure change caused by the decreasing size of the channel, the fluid will experience increased shear force as it flows down the channel, when compared to a linear and/or uniform channel. This increase shear force can allow more homogenising reactions to occur as the fluid flows down the channel, thereby increasing the yield of the process.

From the shapes described the most preferable would be the frustro conical geometry. For the point at the top of the cone and pyramid geometries would be prone to wear, especially when placed within the fluid flow, and would therefore be a weak point and be likely to break off under the force of the fluid flow, also, if the point does wear or break, it will likely block the gap/channel around the impact head, which may require the process to be stopped in order to clear the gap around the impact head, or will at least reduce the yield of the process. It is also noted that the frustro conical, and frustro pyramidal geometries provide a flat impact surface, which increases the force applied to the fluid during the initial impact with the impact head, which again improves the yield of the process, and is why it is preferable that the flat surface of the impact head be at least as wide as the fluid flow, so that all of the fluid impact the flat surface first. However, similar to the point of the cone and pyramid, the edges on the sides of a pyramid geometry may be worn as the fluid flows down the sides of the impact head, as the narrow edges are prone to wear, and as a result the edges may wear down producing debris that may block the gap around the impact head.

One way to help overcome the problem of wear to the impact head may be to have an impact head that can rotate, wherein the impact head may rotate freely, or be driven by a pneumatic system, or motor. In either case the rotation of the impact head will help reduce wear by spreading the force exerted by the fluid on the impact head over a larger area. Also, if the impact head becomes worn, a freely rotating impact head may be rotated by the uneven force, and will help expose an unworn area to the parts of the fluid flow causing the most wear. The impact head may also utilise both free and driven rotation, have a system programmed to rotate the impact head by a specific amount at predetermined time, while freely rotating between these moments. This combined method can help ensure the force of the fluid flow is spread over the widest possible area, and that worn areas can move out of the fluid flow when necessary. It is also noted that the driving/pneumatic system may also be used to adjust the position of the impact head relative to the fluid flow, this may be used to expose different areas of the impact head to the fluid flow, and may also be used to change the size, or shape, of the gap/channels surrounding the impact head to a desired shape to maximise the force exerted on the fluid as it passes through the channel.

It is also noted that the same effect could be achieved by using a housing with a sloped geometry, regardless of the shape of the impact head. In particular the housing would comprise sloped walls to create gaps/channels around the impact head, with the same properties described above. As the sloped housing would create a channel around the impact head with a varying width/radius, and as the channel gets narrower the force on the fluid within would increase, thereby increasing the likelihood of a successful reaction occurring. The walls of the sloped housing may be shaped so as to form a conical, or pyramid space, with the fluid source at the imaginary point of said space, and with the impact head positioned within the frustrum of the conical/pyramidal space. Alternatively, the housing may be positioned to have the point of the conical/pyramidal space be at the far end of the homogeniser, relative the fluid source, so that the channels become narrower as the fluid flows away from the impact head. This way the fluid has a chance to accelerate before reaching the narrowest point of the gap between the housing and the impact head, which may increase the force exerted on the fluid within the channel. Also, it is noted that like the impact head, the conical shaped space may be preferable for the housing, as this shape would remove the narrow edges that may be more prone to wear. The housing may also be configured to rotate to help reduce wear to the housing walls in the same manner as the rotating impact head.

Another method that may be utilise to reduce wear to either the impact head, housing or both, by having the part of the homogeniser being made of a tough material, such as a metallic alloy, or diamond, as such materials will be more resilient to the wear caused by the continuous force produced by the fluid flow. Further examples of suitable materials include; tungsten carbide, zirconia, silicon nitride, alumina silicon carbide, and boron nitride. However, to make the entire impact head, or housing, out of such materials may be too expensive, and may prove to be impractical as some tough materials will be hard to shape into the desired geometry. To help address this issue the impact head and/or housing walls may comprise a protective layer, made from the aforementioned tough materials, positioned on the surfaces of the impact head and housing that are exposed to the fluid flow. These layers may also be made by embedding small pieces of a tough material into the surfaces of the impact head and/or housing, such as small pieces of diamonds, typically by heating the desired surface then forcing the tough material into the heated surface. It should also be noted that try to form these tough layers onto curved surfaces, such as the surface of a conical impact head and/or housing, may be difficult, as you would need to create a single, continuous curved layer.

Figure 1 depicts a general example of an impact head 20 configured for a homogenizer, in particular a flat impact head, surrounded with a housing 10, 10' with flat sides. In these cases the fluid flow will impact on the top surface, wherein the force of the impact will cause a large number of homogenising reactions. Then the fluid will flow across the impact head 20 and impact the flat side of the housing 10,10', which may cause further homogenisation reactions. After these impacts the fluid will then flow down the gaps around the impact head 20, which has a fixed profile defined by the radius of the flat impact head.

The Impact head 20 of Fig. 1, further comprises a pneumatic system for adjusting the position of the impact head within the housing, represented on the figures by the arrows 30. In the depicted example the hydraulic system can move the impact head in a direction parallel to the direction of the fluid flow, moving the impact head 20 closer to, or further from, the fluid source. Such motion can alter the path length which the fluid must travel before impacting upon the impact head 20, this may affect the velocity of the fluid just before the moment of impact, which in turn will change the force applied to the fluid as it impacts the impact head 20, this may be used for example to counteract the effects of wear on the impact head, by moving the impact head 20 away from the source so that the fluid has a longer path and therefore more acceleration before the impact, in the case where the fluid flow downwards. In other designs the impact head may need to be moved towards the fluid source to increase the impact on the fluid, for example when the fluid is pressurised and flow upwards, or horizontally towards the impact head, resulting in the fluid decelerating the further it travels from the fluid source. This increase in the force generated by the initial impact can help compensate for the force loss due to the surface of the impact head be In the above-mentioned example, the impact head 20 would be at a fixed distance from the surrounding housing 10,10' said distance would be predetermined to provide the most amount of shear force to the fluid as it passes through the gap between the impact head 20 and the housing 10,10'. Though as previously mentioned these channels, or gaps, are at risk of becoming blocked, usually due to debris as the impact head 20 becomes worn. In the claimed invention, this problem can be avoided by adding further pneumatic systems, which will allow the impact head to move both vertically and horizontally. This way the impact head gains the above-mentioned benefit of allowing the impact head to move vertically, to change the fluid velocity at the point of impact. While also allowing the impact head to move horizontally, to increase the size of the gap/channel between the impact head 20 and the housing 10,10', to remove any blockages that have formed. This allows the operator a means to remove blockages from the homogeniser without needing to halt any ongoing processes, thereby allowing the homogeniser to continue operations while the blockage is removed. This should allow the user to minimise the yield losses caused by such blockages.

In another embodiment, the impact head 20 may be sloped, or angled, instead of flat, liked the impact head 40 depicted in Figure 2. This angled impact head 40, may have one or more sloped/angled faces facing towards the sides of the housing 10,10', with the narrower end of the impact head facing the fluid flow. These angled surfaces may allow the user to change the size of the gap/channel around the impact head, by moving the impact head vertically.

For, as the narrow end of the impact head is moved towards the fluid source, the base of the impact head, within the walls of the housing, becomes wider, thereby reducing the size of the gap between said impact head 40 and the housing 10,10'. Similarly, by moving the end of the impact head 40 away from the fluid source, the base of the impact head, within the house, becomes narrower, thereby making the gap between the impact head 40 and the housing 10,10' wider. This mechanism may be used to widen the channels to remove blockages, thereby removing the need for the horizontal movements described above. This mechanism may also be used to adjust the size of the gap to an ideal size, wherein said ideal size produces the optimal amount of shear force for the fluid being processed, thereby producing a higher yield. This may be necessary in processes where different fluids will pass through the same homogeniser, or in systems where a fluid is processed and then feed back into the system for further processing cycles. As the average molecule size within the different fluids may require different shear forces for the desired homogenising reaction. Likewise, when a fluid is fed back into the homogeniser for further processing, it would be understood that the processed fluid would contain smaller molecules on average compared to the original fluid, and therefore more shear force may be needed to react the unreacted fluid from the original cycle of the process, or to cause a further desired reaction within the processed fluid, which requires a different level of shear forced compared to the original reaction.

Figure 3 depicts an embodiment wherein the impact head 50 is flat, and instead it is the sides of the housing 60,60' that are sloped/angled. Note that in this embodiment, the narrow ends of the housing walls, meaning the end of the housing with the largest gap between the housing walls, faces the impact head 50. With this arrangement, the impact head can still change the size of the gap between the impact head 50 and the housing 60,60' by moving vertically, and as before the gap will become smaller as the impact head 50 moves towards the fluid source, and the gap becoming wider as the impact head 50 moves away from the fluid source.

It should be noted that in both of these sloped embodiments, the corners of the impact head 20,40,50 may cause a problem. Specifically, the corners of the impact head 20,40,50 may be prone to wear, as these areas will be relatively thin compared to the bulk of the impact head 20,40,50. And if the corners are worn down, or broken off by the force of the fluid flow, they will likely create enough debris to block the channels between the impact head 20,40,50 and the housing 10,10',60,60'. And if the corner has broken off entirely, the broken piece of the impact head may be significantly large that the channel, and therefore cannot be unblocked by moving the impact head 20,40,50 alone, thereby requiring the process to be stopped as the blockage is removed, which will cause the operator to lose processing time and therefore reduce the yield of the process. This is likely to be a problem in the embodiment of Figure 3, as the angled housing 60,60' is directing the fluid flow directly towards the corners of the impact head 50, putting said corners under increased pressure, increasing the chance of wear and the risk of the corner breaking. One way to address this issue may be to use an impact head with a rounded shape, such as the cylindrical impact head 20 in Fig.1, or the frustro-conical shaped impact head 40 of Fig.2, as such rounded impact head would not have these vulnerable corners, though it is noted that the edges of the impact surface may still be prone to wear.

To address this issue a further embodiment may use both an angled/sloped impact head 70, and an angled/sloped housing 60,60', thereby removing the corners that were most at risk of breaking, such as the example depicted in Figure 4. As with the previous embodiments, the impact head 70 may move vertically, to change the size of the gap between the impact head 70 and the surrounding housing 60,60', to change the shear force acting on the fluid as it flows through said gap. However, this configuration has removed the impact head corners proximate the housing, replacing them with an angled surface, which is less likely to wear under the force of the fluid flow within the gap. This in turn reduces the risk of the gap/channel between the impact head 70 and the housing 60,60' becoming blocked.

Figures 5A and 5B depicts another embodiment on the invention, wherein the impact head has a frustro-conical shape, similar to the one shown in Fig.2, and the surrounding housing 60 has sloped walls, however In Fig.5A slopes of the impact head 40 and housing walls 60,60' are parallel, like the depiction in Fig.2, while in Fig. 5B the slope of the impact head 40, and the housing 60, are not parallel. This means in the embodiment of Fig.53, the width of the channels between the impact head 40 and the housing 60 is not constant, but instead becomes narrower up to a choke-point/bottle neck formed between the housing 60 and the base of the impact head. In the other embodiments the channels still comprised this choke point at the base of the impact head, which would move as the impact head is moved within the housing, however the channel width before and after this point would be constant if the slopes of the impact head 40 and housing 60 were parallel. However, with these nonparallel slopes the channels become narrower as they approach the choke-point. Such channels may be used increase the pressure of the fluid as it flows through the channel, as this may help increase the amount of frictional/shearing force exerted on the fluid as it reaches the choke-point, thereby adding force gradually over the length of the channel, rather than a single sudden impact of force at the choke-point, wherein the gap/channel is at its narrowest. This may help to improve the overall yield by increasing the probability of a successful homogenising reaction within the channel.

It should also be noted that each of the depicted impact heads 20,40,50,70 have a flat impact surface on the side facing the fluid flow, with the sloped surfaces surrounding the impact surface. It is noted that this is preferable, as the flat surface provides more frictional force for the initial impact increasing the yield of said impact, also because if the tip of the impact head was a narrow edge, or point, it may be prone to wear, and may possibly break off, thereby blocking the gap around the impact head. Therefore, it is preferable that the impact head has a flat impact surface, more preferably with a width, or radius, similar to that of the fluid flow, so that all of the initial impact occur on the flat impact surface.

Figure 6 depicts an embodiment similar to that of figures 2 and 5, however in this example the impact head 80, has a conical geometry, specifically a cone with a rounded, or domed, point. As previously mentioned, if an impact head 20,40,50,70,80 was to have any points, corners or edges within the fluid flow these points could form weak points that are prone to wear, and may even break off entirely blocking the gap between the impact head 20,40,50,70,80 and the housing with the debris formed. One way to help reduce the risk of this happening, as previously mentioned, was to allow the impact head 20.40.50.70.80 to rotate within the housing to help spread the force exerted on the impact head over a larger area. Another possibility is to round off these potential weak points, like the point of the cone in Fig. 6. This way again the force of the fluid flow is spread over a wider area, thereby reducing the force on these potential weak points, reducing the risk of wear. One potential drawback of such designs is that the rounded points would exert less force onto the fluid during an impact, so a user would need to calculate if the reduce maintenance costs caused by the reduces wear on the impact head 80, would counteract the potential loss of yield caused by the reduced force, for as stated a flat impact surface provides the most force during the initial impact. However, in regards to corners and edges, or any points that are not on the initial impact surface, this round should have little effect on the yield, and as stated may reduce the cost of maintenance by extending the operational lifespan of the impact head 20,40,50,70,80, due to the reduced wear.

Another means of reducing wear mentioned above, was to include a tough material layer, or to embed particulate of such a tough material into the surface of the impact head 20,40,50,70,80, and for the surface of the housing walls 10,10',60,60'. However, such layers can be difficult to form on curved surfaces, such as the curved sides of a conical, or fustroconical impact head, instead it would be preferable to have an impact head with flat surfaces that these protective layers could be easily grafted onto. For this purpose, a pyramid, or fustro-pyramid shape may be preferred. Further, it may also be preferable that these pyramidal shaped impact heads have a base with many sides, such as the example impact head 90 depicted in Figure 7. For such a pyramidal shape will have more obtuse, or wider, angles between the flat faces, such edges would be less prone to wear compared to narrower, more acute, edges. Note that such impact heads 90 may also utilise rounded corners/edges, and impact head rotations to further reduce wear.

In summary the claimed invention provides an improve impact head, configured for use in a homogeniser, by providing an impact head that includes a pneumatic system for repositioning the impact head within the homogeniser, without stopping the process. And by using a sloped impacted head, sloped housing walls, or both to allow the size of the gaps between the impact head and the surrounding housing to be adjusted. These adjustments may include widening the gap to remove any blockages, or narrowing the gap to increase the force applied to the fluid entering the gap, as this increased force will increase the probability of the desired homogenising reaction occurring in the fluid as it flows through the homogeniser.

Claims

Claims: 1) A homogenizer comprising: An impact head (20,50); A housing (10,10') surrounding the impact head, in a manner to form a gap between the impact head and the housing through which a fluid may flow; wherein the impact head (20,50) comprises a sloped impact head (40,70) with a sloped geometry.
2) The homogenizer of claim 1, wherein the sloped impact head has a sloped geometry comprising one of the following: conical, pyramidal, frustro-conical, or frustro-pyramidal geometry.
3) The homogenizer of claims 1 and 2, wherein the impact head (20) further comprises a pneumatic mechanism configured to move the impact head (20) within the housing (10,10').
4) The homogenizer of any preceding claim, wherein the housing (10,10') comprises one or more sloped housing walls (60,60'), so as to form a sloped space in which the impact head is placed.
5) the homogenizer of claim 4, wherein the sloped space formed by the sloped housing walls (60.60') has one of a conical, a pyramidal, a frustro-conical, or a frustro-pyramidal geometry.
6) the homogenizer of claims 1 to 5, wherein the sides of the housing walls (10,10',60,60') and the slopped sides of the impact head (20,40,50,70) are non-parallel.
7) The homogenizer of any preceding claim, wherein the impact head (20, 40,50,70) is configured to rotate within the housing (10,10').
8) The homogenizer of claim 7, wherein the impact head (20,40,50,70) is configured to rotate freely, or to be driven to rotate at specific intervals, or both.
9) The homogenizer of any preceding claim, wherein the impact head (20,40,50,70) comprises at least one flat impact surface.
10) The homogenizer of any preceding claim, wherein the impact head (20,40,50,70), and/or housing walls (10,10',60.60') are formed from a tough material, or comprises a protective layer over their impact surfaces, that comprises either a layer placed over the impact surface, or small particles embedded within the impact surface.
11) The homogenizer of claim 10, wherein the tough material comprises at least one of tungsten carbide, zirconia, silicon nitride, alumina silicon carbide, boron nitride or diamond.
12) The homogenizer of any preceding claim, wherein the homogenizer is configured to produce graphene, graphene nanoplates (GNP), or similar atomic scale materials, by the delaminafion of a bulk material.
13) The homogenizer of claim 12, wherein the atomic scale material, comprises a laminar material.
14) The homogenizer of claims 12 and 13, wherein the bulk material comprises solid particles of at least one of graphite, hexagonal boron nitride or molybdenum disulphide, or an aqueous suspension of graphite.
15) A method for using the homogeniser of any preceding claim, wherein the homogeniser receives a fluid from a fluid source; The flow of the received fluid is directed towards the impact surface of the impact head (20,40,50,70); After impacting the impact head (20,40,50,70), the fluid flows over the impact head (20,40,50,70) towards the walls of the housing (10,10',60,60'), wherein the fluid impacts the housing walls (10,10,60,60'); The fluid then flows into a gap between the impact head (20,40,50,70) and the housing (10,10,60,60') to exit the homogeniser.
16) The method of claim 15, wherein the impact head (20,40,50,70) may be moved via a pneumatic system, to widen or narrow the gap between the impact head (20,40,50,70) and the housing (10,10,60,60').
17) the method of claims 15 or 16, wherein the impact head (20,40,50,70) may also be moved closer to, or further from the fluid source, to alter the force generated when the fluid impacts upon the impact surface.
18) the method of claims 15 to 17, wherein on determining that the gap between the impact head (20,40,50,70) and the housing (10,10',60,60') is blocked, or partially blocked, the pneumatic system will move the impact head (20,40,50,70) in a manner to widen the gap and allow the blockage to pass through the homogeniser.
19) the method of any preceding claim, wherein the pneumatic system moves the impact head (20,40,50,70) to narrow the gap between the impact head (20,40,50,70) and the housing (10,10,60,60'), to increase the shear force applied to fluid flowing through the gap 20) the method of any preceding claim, wherein some or all of the fluid exiting the homogeniser, flows back to the fluid source to re-enter the homogeniser; and On determining the fluid is re-entering the homogeniser the pneumatic system automatically, moves the impact head (20,40,50,60) to narrow the gap between the impact head (20,40,50,70) and the housing (10,10,60,60'), to increase the shear force applied to fluid flowing through the gap.21) the method of any preceding claim, wherein different fluids enter the homogeniser at different times in a process; VVherein the pneumatic system automatically adjusts the position of the impact head (20,40,50,70), to provide a predetermined amount of force to each fluid as it enters the homogeniser.