GB2619033A

GB2619033A - Densification apparatus and method

Info

Publication number: GB2619033A
Application number: GB2207609.5A
Authority: GB
Inventors: Bristoe Flockhart Kenneth
Original assignee: Changeover Tech Ltd
Current assignee: Changeover Tech Ltd
Priority date: 2022-05-24
Filing date: 2022-05-24
Publication date: 2023-11-29
Also published as: WO2023227878A1; GB202207609D0

Abstract

A densification apparatus (118) for densifying a mixture comprising carbonaceous particulates and water, having a densification unit 160 comprising: a densification chamber 168 and at least one densifying member 182 configured to apply a kneading, shearing and spatulating action. The densifying member(s) may comprise a wheel 182 arranged to roll along an inner surface of the densification chamber, and a mixer member 194 arranged to rotate within the chamber. Also claimed is a method of densifying a mixture comprising carbonaceous particulates and water, comprising: supplying the mixture to a densification chamber of a densification unit; and actuating a densifying member such that kneading, shearing and spatulating action is applied to increase the mixture’s density. The mixture may comprise not less than 10 wt.% water, and a binder (e.g. polysaccharide or polyvinyl alcohol binder; 0.1-2 wt.% of dry mixture) and cross-linker (e.g. bis-aldehyde, bis-acid; 0.01-10 wt.%) may also be added.

Description

DENSIFICATION APPARATUS AND METHOD

Technical Field

The present invention relates to a densification apparatus and method for densifying a mixture comprising carbonaceous particulates.

Background

A continuing problem in many solid-based fuel extraction processes is dealing with waste 'fine' materials. As much as 40% of run-of-mine coal can end up as fine (generally about <3mm) or ultrafine (generally about <0.1mm) coal dust. This fine coal is often unsuitable for the end process, and, even where the size is not a problem, retains large amounts of water (10%-30%) which can make it "sticky", difficult to process, and inefficient to handle transport and burn.

One solution has been to form briquettes. Another solution is to agglomerate carbonaceous fines using various processes, including pelletising and extruding. Some processes involve the need for some sort of treatment of the pellets after their formation, generally drying at an elevated temperature, so as to provide the final form of the pellets.

Another problem is the weight of moisture. High moisture levels in coal make transportation and combustion inefficient. Sub-bituminous coals, which comprise a large and valuable part of the world's coal reserves, contain "chemically attached" moisture within the coal structure (up to 20%-30% moisture). This "moisture" severely limits the use and value of sub-bituminous coals. For example, for every three truckloads of coal that is transported, one truckload of water must also be transported. That moisture also takes (i.e. robs) energy from the flame (to turn the water into steam) as the coal is burnt. Attempts to drive the moisture out by heating have proved unsuccessful because the coal falls apart as it dries, and also becomes susceptible to spontaneous combustion. As a result, very little sub-bituminous coal is traded internationally.

A further problem is using additives which may lead to an increase in the formation of environmentally harmful substances or gases upon burning, in particular sulphur gases such as sulphur dioxide, and various nitrogen gases generally termed 'NOX' gases.

W02006/003354A1 and W02006/003444A1 describe a process for producing fuel pellets based on mixing a particulate carbon-based material and a binder, and agglomerating the mixture by the action of tumbling.

W02021/094784A1 and W02021/094786A1 describe a pelletisable formula and process for forming a fuel pellet from a particulate carbonaceous material.

It is an object of the present invention to provide an improvement to the process of forming a fuel pellet from a mixture of particulate carbonaceous material and water, in particular a mixture of particulate carbonaceous material and water having not less than 10wt% water.

Summary of the Invention

According to a first aspect of the invention there is provided a densification apparatus for densifying a mixture comprising carbonaceous particulates and water, the densification apparatus having a densification unit comprising: a densification chamber; and at least one densifying member configured to apply a kneading, shearing and spatulating action to a mixture comprising carbonaceous particulates and water within the densification chamber.

Optionally, the densification chamber has an inner surface and the at least one densifying member comprises a wheel arranged to roll along an inner surface of the densification chamber.

Optionally, the at least one densifying member further comprises a mixer member arranged to move within the densification chamber such that the mixture is moved upwardly within the densification chamber by the mixer member.

Optionally, the mixer member is arranged to rotate within the densification chamber about a rotational axis.

Optionally, the rotational axis of the mixer member extends vertically within the densification chamber.

Optionally, the inner surface is a lower surface of the densification chamber and the densification chamber has a second inner surface which extends upwardly from the lower surface, and wherein the mixer member is spaced from the lower surface and the second inner surface.

Optionally, the mixer member is spaced from the lower inner surface by a predetermined distance which is not less than 5mm. Optionally, the mixer member is spaced from the lower inner surface by a predetermined distance which is not greater than 100mm, such as not greater than 30mm.

Optionally, the mixer member is spaced from all inner surfaces of the densification chamber.

Optionally, the densification apparatus further comprising a first scraper arranged to contact the lower surface.

Optionally, the densification apparatus further comprising a second scraper arranged to contact the second inner surface.

Optionally, the second inner surface is cylindrical.

Optionally, the densification apparatus further comprises an agitation unit having an agitation chamber and an agitating member configured to agitate a mixture comprising carbonaceous particulates and water within the agitation chamber prior to supply of the mixture to the densification unit.

Optionally, the agitating member comprises a plurality of paddles arranged to rotate within the agitation chamber.

Optionally, the densification chamber is a first densification chamber and the densifying member is a first densifying member, and the densification unit further comprises a second densification chamber and a second densification member configured to apply a kneading, shearing and spatulating action to a mixture comprising carbonaceous particulates and water within the second densification chamber, the first densification chamber and the second densification chamber being in fluid communication with each other via a transition opening such that a mixture can move through the transition opening during use.

Optionally, the densification apparatus further comprises a moisture analyser configured to determine a water content of said mixture comprising carbonaceous particulates and water being supplied to the densification chamber.

Optionally, the densification apparatus further comprises a liquid supply apparatus arranged to supply liquid to said mixture comprising carbonaceous particulates and water. The liquid supply apparatus may be configured to supply a liquid comprising water and/or a cross-linker.

According to a second aspect of the invention there is provided a method of densifying a mixture comprising carbonaceous particulates and water using a densification apparatus having a densification unit comprising a densification chamber and at least one densifying member configured to apply a kneading, shearing and spatulating action to a mixture within the densification chamber, the method comprising the steps: supplying a mixture comprising carbonaceous particulates and water to the densification chamber of the densification unit; and actuating the densifying member of the densification unit such that a kneading, shearing and spatulating action is applied by the densifying member to the mixture thereby increasing the density of the mixture.

Optionally, the mixture comprises not less than 10wt% water, such as not less than 20wt% water. In certain embodiments, particularly with mixtures comprising a biomass, the mixture may comprise not less than 40wt% water, such as not less than 50wt% water.

Optionally, the carbonaceous particulates have a particle size which is not greater than 1mm.

Optionally, the carbonaceous particulates have a particle size which is not greater than 0.5mm.

Optionally, the method further comprises the step of adding a binder to the mixture.

Optionally, the binder comprises 0.1wt% to 2wt% of the total dry weight of the mixture of carbonaceous particulates and binder. For example, the binder may comprise 0.2wt% to 0.7wt% of the total dry weight of the mixture of carbonaceous particulates and binder.

Optionally, the binder comprises a polysaccharide or a polyvinyl alcohol binder.

Optionally, the binder is added to the mixture before supplying the mixture to the densification chamber. Optionally, the binder may be added during an agitation step prior before supplying the mixture to the densification chamber.

Optionally, the method further comprises the step of adding a cross-linker to the mixture.

Optionally, the cross-linker is a bifunctional reagent able to co-ordinate two separate polymer chains, such as at least one of bis-aldehyde; a bis-acid; a carbonate or a borate containing one or more ions of the group comprising: titanium, sodium, ammonia, zirconium, potassium or calcium; zirconium carbonate and sodium borate.

Optionally, the cross-linker is added to the mixture at a weight ratio of between 1g and 1kg of cross linker per 10kg of dry weight of the mixture.

Optionally, the cross-linker is added to the mixture prior to actuation of the densifying member.

Optionally, the method further comprises the step of supplying a liquid comprising water to the mixture of carbonaceous particulates and water.

Optionally, the densification apparatus further comprises an agitation unit comprising an agitation chamber and at least one agitation member configured to agitate the mixture, and the method further comprises the steps: supplying the mixture to the agitation chamber of an agitation unit; and actuating an agitation member of the agitation unit thereby agitating the mixture. Optionally, the cross-linker is added to the mixture prior to and/or during agitation of the mixture by the agitation member.

Optionally, the densification apparatus is the densification apparatus of the first aspect of the invention.

In the context of the invention, the 'particle size' of a particle, such as a particle having an irregular shape, may be defined as a diameter of a representative sphere having the same volume as the particle.

In the context of the invention, reference to particulates having a particular 'particle size', particularly when used in reference to carbonaceous particulates, means a particulates having no more than 10%w/w greater than the stated particle size in mm. Furthermore, the term having a particle size or 'having a particle size which is not greater than 1mmi, particularly when used in reference to carbonaceous particulates, means particulates having no more than 10%w/w >1.0mm, and having no less than 5%w/w <38pm (microns). A particle size distribution may, in particular, be determined in accordance with ISO 13320:2020.

Certain aspects of the invention provide an economic means for converting coal fines into useable pellets.

Various further features and aspects of the invention are defined in the claims.

Unless defined otherwise, all technical and scientific terms used herein have the meaning commonly understood by a person skilled in the art to which this invention belongs.

Brief Description of the Drawings

Embodiments of the present invention will now be described by way of example with reference to the accompanying drawings where like parts are provided with corresponding reference numerals and in which: Figure 1 is a representative view of a facility for pelletising a particulate carbonaceous material; Figure 2 is a representative view of selected apparatus of the facility shown in Figure 1; Figure 3 is a perspective view of a densification apparatus; Figure 4 is a perspective sectional view of an agitation system of the densification apparatus shown in Figure 3; Figure 5 is a perspective sectional view of a densification system of the densification apparatus shown in Figure 3; Figure 6 is a sectional view of a portion of a densification system shown in Figure 5; and Figure 7 is a representative view of selected apparatus of the facility shown in Figure 1.

Detailed Description

Figure 1 is a schematic illustration of a facility 102 for pelletising a particulate carbonaceous material.

The facility 102 comprises a particulates storage station 104, a densification station 106, a pelletising station 108, a sorting station 110 and a pellet storage station 112.

The particulates storage station 104 comprises a shelter in which particulate carbonaceous material P, such as coal fines, is stored prior to processing.

With reference to Figures 2 and 3, the densification station 106 comprises an access ramp 114, a feed-regulator 116, a densification apparatus 118 and a shelter 120. The densification apparatus 118 shown in Figures 2 and 3 is representative only.

The feed-regulator 116 comprises a hopper 122 and a lateral conveyor 124. The hopper 122 is arranged adjacent the top of the access ramp 114 such that a vehicle V mounting the access ramp 114 can deposit particulate carbonaceous material from the vehicle V into the hopper 122. The lateral conveyor 124 is arranged below the hopper 122 such that particulate carbonaceous material exiting from the bottom of the hopper 122 is transported to the densification apparatus 118.

With additional reference to Figures 3 and 4, the densification apparatus 118 comprises a feed conveyor 126 (shown in Figure 2), an agitation system 128 and a densification system 130. The feed conveyor 126 is arranged to receive particulate carbonaceous material from the lateral conveyor 124 transport it to the agitation system 128.

The agitation system 128 comprises an agitation unit 131 having a lower wall 132, an upper wall 134 and a side wall 136 extending therebetween.

The lower wall 132, upper wall 134 and side wall 136 define an agitation chamber 138.

The agitation chamber 138 is generally cylindrical having a longitudinal axis that extends vertically. An inlet chute 139 is provided at a side of the agitation chamber 138. A moisture analyser (not shown) is provided at the inlet chute 139. The moisture analyser is configured to determine the moisture content of a mixture as it enters the agitation system 128. The moisture analyser may be an infrared (IR) moisture analyser such as a near-infrared moisture analyser that determines the moisture content of a mixture based on a the amount of IR light reflected by a mixture as it passes through the inlet chute 139.

The agitation chamber 138 has an outlet opening 140 provided in the lower wall 132 diametrically opposite the inlet chute 139 such that a mixture may flow from the agitation chamber 138 onto a second feed conveyor 142 arranged below the outlet opening 140.

An outlet door 144 is disposed at the outlet opening 140 and arranged to control and/or prevent flow of a mixture from the agitation chamber 138 onto the second feed conveyor 142. The outlet door 144 is substantially planar and shaped to occlude the outlet opening 140. The outlet door 144 is arranged to rotate between an open configuration in which the outlet door 144 is rotated outwardly from below the agitation chamber 138 and a closed configuration in which the outlet door 144 occludes the outlet opening 140. The outlet door 144 is controlled by a first actuator 146 disposed externally of the agitation unit 131. The first actuator 146 may be any suitable actuator such as a hydraulic actuator, a pneumatic actuator or an electromechanical actuator.

An agitation member 148 is disposed within the agitation chamber 138. The agitation member 148 comprises a rotor 150, four upper paddles 152, four lower paddles 154, four mid paddles 156 and two scrapers 158. The upper paddles 152 and mid paddles 156 are spaced equidistantly around the rotor 150 and extend radially outwardly from the rotor 150 from offset positions. The lower paddles 154 are spaced diametrically opposite each other and extend radially outwardly from the rotor 150 from offset positions. The two scrapers 158 are disposed between the four lower paddles 154 and extend directly radially outwardly from the rotor 150. The rotor 150 is arranged to rotate around a rotational axis that extends coaxially with the longitudinal axis of the agitation chamber 138. The upper paddles 152, lower paddles 154 and mid paddles 156 are arranged to agitate a mixture within the agitation chamber 138 as the agitation member 148 rotates. The two scrapers 158 are arranged to scrape the lower surface of the agitation chamber 138 as the agitation member 148 rotates.

The densification system 130 comprises a densification unit 160 having a lower wall 162, an upper wall 164 and a side wall 166 extending therebetween.

With additional reference to Figures Sand 6, the lower wall 162, upper wall 164 and side wall 166 define a first densification chamber 168 and a second densification chamber 170.

Each of the first densification chamber 168 and second densification chamber 170 is generally cylindrical having a longitudinal axis that extends vertically.

The first densification chamber 168 is connected to the second densification chamber 170 via a transition opening 172. An inlet chute 174 is provided at the side of the first densification chamber 168 diametrically opposite the transition opening 172. An inlet hopper 173 is disposed above the chute 174 and arranged to receive a mixture from the second feed conveyor 142. A spray bar 175 of a liquid supply apparatus is disposed at an upper region of the inlet hopper 173. The spray bar 175 comprises nozzles 175a which are arranged to direct a liquid into the inlet hopper 173. An outlet opening 176 is provided in the lower wall 162 of the second densification chamber 170 diametrically opposite the transition opening 172.

An outlet door 178 is disposed at the outlet opening 176 and arranged to control and/or prevent flow of a mixture from the second densification chamber 170 out of the densification unit 160 through the outlet opening 176. The outlet door 178 is substantially planar and shaped to occlude the outlet opening 176. The outlet door 178 is arranged to rotate between an open configuration in which the outlet door 178 is rotated outwardly from below the second densification chamber 170 and a closed configuration in which the outlet door 178 occludes the outlet opening 176. The outlet door 178 is controlled by a second actuator 180 disposed externally of the densification unit 160. The second actuator 180 may be any suitable actuator such as a hydraulic actuator, a pneumatic actuator or an electromechanical actuator.

A first densifying member 182 is disposed within the first densification chamber 168. The first densifying member 182 comprises a rotor 184, a first densifying wheel 186, a second densifying wheel 188, a side wall scraper 190, a lower wall scraper 192 and a mixer member 194.

The rotor 184 is arranged to rotate around a rotational axis that extends coaxially with the longitudinal axis of the first densification chamber 168.

The first densifying wheel 186 is secured to the rotor by a support structure 196 which allows the first densifying wheel 186 to pivot up and down in an arc about a pivot axis which is perpendicular to the rotational axis of the rotor 184 and spaced from the rotational axis of the rotor 184 by an amount which allows the rotor 184 to accommodate varying depths of material within the first densification chamber 168 and to exert a kneading action on the mixture as the first densifying wheel 186 rolls within the first densification chamber 168. The first densifying wheel 186 is arranged to rotate freely about its rotational axis and such that, as the rotor 184 is rotated, the first densifying wheel 186 is fee to roll along the lower surface first densification chamber 168 in a circular path. The rotational axis of the first densifying wheel 186 itself extends perpendicular to the rotational axis of the rotor 184 and is slightly offset to the rotational axis of the rotor 184 so as to exert a shearing action when the first densifying wheel 186 rolls within the first densification chamber 168. The first densifying wheel 186 has a width relative to the distance of the wheel from the rotational axis of the rotor 184 which results in the first densifying wheel 186 generating a spatulating action across the face of the first densifying wheel 186.

The second densifying wheel 188 has the same construction as the first densifying wheel 186 and is secured to the rotor by the support structure 196 in the same manner as the first densifying wheel 186, but is disposed diametrically opposite the first densifying wheel 186.

The second densifying wheel 188 is therefore arranged to exert a kneading, shearing and spatulating action on a mixture within the first densification chamber 168 as the second densifying wheel 188 rolls within the first densification chamber 168 about the rotational axis of the rotor 184.

The side wall scraper 190 is supported by the support structure 196 and extends parallel with the rotational axis of the rotor 184 in contact with the side wall 136. The side wall scraper 190 is therefore arranged to scrape the upwardly extending inner surface of the first densification chamber 168. The lower wall scraper 192 is supported by the support structure 196 and extends radially outwardly from the rotational axis of the rotor 184 in an arc and in contact with the lower wall 132. The lower wall scraper 192 is therefore arranged to scrape the horizontal lower inner surface of the first densification chamber 168.

The mixer member 194 is supported by the support structure 196 and comprises a beam that extends perpendicularly to the rotational axis of the rotor 184 between the first densifying wheel 186 and the second densifying wheel 188. The mixer member 194 is spaced from the lower wall 132 and the side wall 136 such that it does not contact the inner surfaces of the first densification chamber 168. In particular, the 194 is spaced from the lower wall 132 by a predetermined distance which is not less than 5mm and may be not greater than 100mm, such as not less than Smm and not greater than 30mm. The mixer member 194 is substantially planar and extends in a plane which is parallel with the lower internal wall of the first densification chamber 168 formed by the lower wall 132. The mixer member 194 has an inclined leading edge 198, as shown in Figure 6, which is arranged to direct mixture upwardly within the first densification chamber 168 as the mixer member 194 is rotated.

A second densifying member 282 is disposed within the second densification chamber 170.

The second densifying member 282 is identical to the first densifying member 182 and so comprises a rotor 284, a first densifying wheel 286, a second densifying wheel 288, a side wall scraper 290, a lower wall scraper 292, a mixer member 294 and a support structure 296 which are arranged in accordance with the first densifying member 182. The second densifying member 282 is, however, arranged to be out of phase with the first densifying member 182.

That is to say, the rotational axes of the first and second densifying wheels 186, 188 of the first densifying member 182 extend perpendicularly to the rotational axes of the rotational axes of the first and second densifying wheels 286, 288 of the second densifying member 282.

With reference to Figure 7, which is a representative view of a pelletising station and a sorting station which may be used in the facility shown in Figure 1, the pelletising station 108 comprises a feed conveyor 302 and a pelletising apparatus 304 comprising a rotatable drum 306 in which the mixture is tumbled by fins disposed along the inside of the drum 306 as the mixture moves along the drum 306.

The sorting station 110 comprises a feed conveyor 402 and a grizzly hopper 404 which is configured to select pellets having a size within a predetermined range, such as not less than 3mm and not greater than 12mm for drying and storage. It will be appreciated that the selected pellet size will be dependent on the intended purpose of the pellets. In general, a predetermined range of pellet size will be not less than 3mm and not greater than 75mm, but a suitable sub-range may be selected depending on the carbonaceous material and the intended purpose of the pellets. The predetermined range of not less than 3mm and not greater than 12mm is considered particularly suitable for coal fines.

Referring again to Figure 1, the pellet storage station 112 comprises a pellet feed-regulator 502 comprising a feed conveyor 504, a hopper 506, storage conveyor 508 and storage area 510. The feed conveyor 504 is arranged to transport pellets selected by the sorting station 110 to the hopper 506, which delivers them to the storage conveyor 508 and a predetermined rate. The storage conveyor 508 is arranged to transport the pellets to the storage area 510 for storage and drying.

In use, a mixture of particulate carbonaceous material and water is collected from the particulates storage station 104 by a vehicle V, such as a vehicle having a mechanical shovel, and deposited in the hopper 122 of the feed-regulator 116. In the embodiment shown, the mixture is a mixture of coal fines having a particle size which is not greater than 1mm and a water content of not less than 10% and not greater than 40%. The density of the mixture is typically between 600 Kg/m3 and 700Kg/m3.

Other forms of particulate carbonaceous material include peat, lignite through to sub-bituminous coals, metallurgical coal, anthracite fines, and petroleum coke fines could be used. Optionally, the particulate carbonaceous material includes a minority amount (<50wt%) of another material or materials, including sewerage wastes, biomass, animal wastes and other hydrocarbon materials that could be considered a fuel source. Biomass is generally also carbon based, and includes one or more of the group comprising; wastewater sludge, sewerage sludge, agricultural litter such as chicken litter, bonemeal, spent mushroom compost, wood, wood chippings etc, plant residues including rape seed, hemp seed, corn and sugar residues, and including by-products of industrial processes.

A mixture comprising a biomass, such as bio carbons in the form of biocha rcoa Is, may have a moisture content which is between 50% and 70% water.

The mixture is then transported by the lateral conveyor 124 to the feed conveyor 126 of the densification apparatus 118, where it is then transported by the feed conveyor 126 upwardly and deposited into the agitation chamber 138 through the inlet chute 139. As the mixture passes through the chute 139 the moisture content of the mixture is determined using the moisture analyser. The actual moisture content is then compared against a predetermined moisture content which known to be optimal for effective densification. A difference between the actual moisture content and the predetermined moisture content is determined and used to generate a pre-set amount of liquid to be added to the mixture which, in the embodiment described, is a pre-set flow rate of liquid that corresponds with the rate of transfer of the mixture to the densification apparatus 118. The predetermined moisture content may be a water content greater than 10wt%, such as a water content which is not less than 20wt%, for example, not less than 40wt% For example, if the predetermined moisture content is 40wt% and the actual moister content is 25wt% then a pre-set amount of liquid is generated which will increase the moisture content by 15wt% to 40wt%.

The outlet door 144 is in its closed configuration thereby retaining the mixture within the agitation chamber 138. A dry binder is added to the agitation chamber 138 for mixing with the mixture, but in other embodiments may be combined with the mixture before the mixture is added to the agitation chamber 138. The binder comprises a polysaccharide or a polyvinyl alcohol binder. An amount of dry binder is selected which, when added, comprises between 0.1wt% to 2wt% based on total dry weight of the particulate carbonaceous material, such as between 0.2wt% to 0.7wt% based on total dry weight of the particulate carbonaceous material.

The mixture is then agitated by rotating the agitation member 148 within the agitation chamber 138 about the rotational axis of the rotor 150 using suitable drive means. This causes the upper paddles 152, lower paddles 154 and mid paddles 156 to rotate within the agitation chamber 138 thus agitating the mixture by pushing the mixture upwardly within the agitation chamber 138. The agitation process reduces the density of the mixture and causes the mixture to 'fluff up'. The two scrapers 158 remove any material deposited on the lower surface of the agitation chamber 138 to be directed upwardly within the agitation chamber 138. Once the density of the mixture has been reduced to a predetermine density, such as a density not greater than 300 Kg/m3, the outlet door 144 is moved to its open configuration to allow the mixture to move through the outlet opening 140 onto the second feed conveyor 142. It is understood that the process of agitating the mixture to reduce its density makes it more susceptible to the subsequent densification process, as explained below.

The mixture is transported by the second feed conveyor 142 to the densification unit 160 and deposited into the inlet hopper 173. At the same time, a liquid comprising a cross-linker and optionally water is added to the mixture via the nozzles 17a of the spray bar 175. If water is require to be added to increase the moisture content of the mixture, the liquid is added at the pre-set flow rate determined previously based on the moisture content of the mixture.

In the described embodiment, the cross-linker is a bifunctional reagent able to co-ordinate two separate polymer chains. For example, the cross-linker may comprise bis-aldehyde; a bisacid; a carbonate or a borate containing one or more ions of the group comprising: titanium, sodium, ammonia, zirconium, potassium or calcium; zirconium carbonate and sodium borate.

The composition of the liquid and the pre-set flow rate is determined such that the cross-linker is added to the mixture at a weight ratio of between 1g and 1kg of cross linker per 10kg of dry weight of the mixture. The combined mixture passes from the inlet hopper 173 through the inlet chute 174 into the first densification chamber 168. The mixture is densified within the first densification chamber 168 by rotating the rotor 184 about its rotational axis using suitable drive means (not shown). This causes the first and second densifying wheels 186, 188 to roll along the inner lower surface of the first densification chamber 168 thereby exerting a kneading, shearing and spatulating action on the mixture. The kneading, shearing and spatulating action reduces both the size of the particles of carbonaceous material and also the size of voids between the particles of carbonaceous material thereby increasing the density of the mixture.

The mixture is free to move through the transition opening 172 into the second densification chamber 170 where the first and second densifying wheels 286, 288 of the second densifying member 282 exert a comparable kneading, shearing and spatulating action on the mixture. It is observed that the combined action of the first densifying member 182 and the second densifying member 282 causes the mixture to move from the first densification chamber 168 to the second densification chamber 170 in a generally figure-of-eight path. This enhances the densification process by reducing the time taken to achieve a predetermined density, and increasing the uniformity of the particle size. Once the density of the mixture has been increased to a predetermined density, such as a density not less than 1200 Kg/m', the outlet door 178 is moved to its open configuration to allow the mixture to exit the second densification chamber 170 through the outlet opening 176 and deposited on the feed conveyor 302 of the pelletising station 108.

The feed conveyor 302 transports the mixture to the rotatable drum 306 of the pelletising apparatus 304. The mixture is tumbled by the fins disposed along the inside of the drum 306 as the mixture moves along the drum 306. The rising and falling action of the mixture within the drum causes the mixture to coagulate into pellets.

As the pellets exit the drum 306 they are deposited on the feed conveyor 402 of the sorting station 110. The feed conveyor 402 transports the pellets to the grizzly hopper 404 which is selects pellets having a size within a predetermined range, such as not less than 3mm and not greater than 12mm for drying and storage. Unselected pellets may be returned to the densification apparatus 118 for reprocessing.

Selected pellets are transported by the feed conveyor 504 of the sorting station 110, to the hopper 506 which deposits the pellets at a predetermined rate on the storage conveyor 508.

The storage conveyor 508 then transports the pellets to the storage area 510 for stacking. The pellets are stored for a predetermined period of time, or until the pellets have a predetermined moisture content before being ready for further processing.

As the pellets are left to stand, the cross-linker is understood to draw the particles of carbonaceous material within each pellet together as the cross-linker cures thereby expelling water from the pellet. This assists with reducing the overall water/moisture content of the pellet and/or reduces drying time.

All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive. Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features. The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

With respect to the use of substantially any plural and/or singular terms herein, those having skill in the art can translate from the plural to the singular and/or from the singular to the plural as is appropriate to the context and/or application. The various singular/plural permutations may be expressly set forth herein forsake of clarity.

It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims are generally intended as "open" terms (e.g., the term "including" or "comprising" should be interpreted as "including but not limited to," the term "having"should be interpreted as "having at least," the term "includes" should be interpreted as "includes but is not limited to," etc.). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases "at least one" and "one or more" to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles "a" or "an" limits any particular claim containing such introduced claim recitation to embodiments containing only one such recitation, even when the same claim includes the introductory phrases "one or more" or "at least one" and indefinite articles such as "a" or "an" (e.g., "a" and/or "an" should be interpreted to mean "at least one" or "one or more"); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should be interpreted to mean at least the recited number (e.g., the bare recitation of "two recitations," without other modifiers, means at least two recitations, or two or more recitations).

It will be appreciated that various embodiments of the present disclosure have been described herein for purposes of illustration, and that various modifications may be made without departing from the scope of the present disclosure. Accordingly, the various embodiments disclosed herein are not intended to be limiting, with the true scope being indicated by the following claims.

Claims

CLAIMS1. A densification apparatus for densifying a mixture comprising carbonaceous particulates and water, the densification apparatus having a densification unit comprising: a densification chamber; and at least one densifying member configured to apply a kneading, shearing and spatulating action to a mixture comprising carbonaceous particulates and water within the densification chamber.
2. The densification apparatus of claim 1, wherein the densification chamber has an inner surface and the at least one densifying member comprises a wheel arranged to roll along an inner surface of the densification chamber.
3. The densification apparatus of claim 2, wherein the at least one densifying member further comprises a mixer member arranged to move within the densification chamber such that the mixture is moved upwardly within the densification chamber by the mixer member.
4. The densification apparatus of claim 3, wherein the mixer member is arranged to rotate within the densification chamber about a rotational axis.
5. The densification apparatus of claim 4, wherein the rotational axis of the mixer member extends vertically within the densification chamber.
6. The densification apparatus of any one of claims 3 to 5, wherein the inner surface is a lower surface of the densification chamber and the densification chamber has a second inner surface which extends upwardly from the lower surface, and wherein the mixer member is spaced from the lower surface and the second inner surface.
7. The densification apparatus of claim 6, wherein the mixer member is spaced from the lower inner surface by a predetermined distance which is not less than Smm.
8. The densification apparatus of claim 6 or 7, wherein the mixer member is spaced from all inner surfaces of the densification chamber.
9. The densification apparatus of anyone of claims 6 to 8, the densification apparatus further comprising a first scraper arranged to contact the lower surface.
10. The densification apparatus of claim 9, the densification apparatus further comprising a second scraper arranged to contact the second inner surface.
11. The densification apparatus of any one of claims 6 to 10, wherein the second inner surface is cylindrical.
12. The densification apparatus of any one of the preceding claims, wherein the densification apparatus further comprises an agitation unit having an agitation chamber and an agitating member configured to agitate a mixture comprising carbonaceous particulates and water within the agitation chamber prior to supply of the mixture to the densification unit.
13. The densification apparatus of claim 12, wherein the agitating member comprises a plurality of paddles arranged to rotate within the agitation chamber.
14. The densification apparatus of any one of the preceding claims, wherein the densification chamber is a first densification chamber and the densifying member is a first densifying member, and the densification unit further comprises a second densification chamber and a second densification member configured to apply a kneading, shearing and spatulating action to a mixture comprising carbonaceous particulates and water within the second densification chamber, the first densification chamber and the second densification chamber being in fluid communication with each other via a transition opening such that a mixture can move through the transition opening during use.
15. The densification apparatus of any one of the preceding claims, further comprising a moisture analyser configured to determine a water content of said mixture comprising carbonaceous particulates and water being supplied to the densification chamber.
16. The densification apparatus of any one of the preceding claims, further comprising a liquid supply apparatus arranged to supply liquid to said mixture comprising carbonaceous particulates and water.
17. A method of densifying a mixture comprising carbonaceous particulates and water using a densification apparatus having a densification unit comprising a densification chamber and at least one densifying member configured to apply a kneading, shearing and spatulating action to a mixture within the densification chamber, the method comprising the steps: supplying a mixture comprising carbonaceous particulates and water to the densification chamber of the densification unit; and actuating the densifying member of the densification unit such that a kneading, shearing and spatulating action is applied by the densifying member to the mixture thereby increasing the density of the mixture.
18. The method of claim 17, wherein the mixture comprises not less than 10wt% water, such as not less than 20wt% water.
19. The method of claim 17 or 18, wherein the carbonaceous particulates have a particle size which is not greater than 1mm, such as not greater than 0.5mm.
20. The method of any one of claims 17 to 19, wherein the method further comprises the step of adding a binder to the mixture.
21. The method of claim 20, wherein the binder comprises 0.1wt% to 2wt% of the total dry weight of the mixture of carbonaceous particulates and binder, such as 0.2wt% to 0.7wt% of the total dry weight of the mixture of carbonaceous particulates and binder.
22. The method of claim 20 or 21, wherein the binder comprises a polysaccharide or a polyvinyl alcohol binder.
23. The step of any one of claims 20 to 19, wherein the binder is added to the mixture before supplying the mixture to the densification chamber.
24. The method of any one of claims 17 to 23, wherein the method further comprises the step of adding a cross-linker to the mixture.
25. The method of claim 24, wherein the cross-linker is a bifunctional reagent able to co-ordinate two separate polymer chains, such as at least one of bis-aldehyde; a bis-acid; a carbonate or a borate containing one or more ions of the group comprising: titanium, sodium, ammonia, zirconium, potassium or calcium; zirconium carbonate and sodium borate.
26. The method of claim 24 or 25, wherein the cross-linker is added to the mixture at a weight ratio of between 1g and 1kg of cross linker per 10kg of dry weight of the mixture.
27. The method of any one of claims 24 to 26, wherein the cross-linker is added to the mixture prior to actuation of the densifying member.
28. The method of any one of claims 17 to 27, further comprising the step of supplying a liquid comprising water to the mixture of carbonaceous particulates and water.
29. The method of any one of claims 17 to 28, wherein the densification apparatus further comprises an agitation unit comprising an agitation chamber and at least one agitation member configured to agitate the mixture, and the method further comprises the steps: supplying the mixture to the agitation chamber of an agitation unit; and actuating an agitation member of the agitation unit thereby agitating the mixture.
30. The method of any one of claims 17 to 29, wherein the densification apparatus is the densification apparatus of any one of claims 1 to 16.