AU2018274977A1 - A system for providing a continuous stream of foamed cement product and a Mixing and Pump Apparatus, System and an Associated Method for Providing a Stream of Foamed Cement Material - Google Patents

Abstract

Abstract A system for providing a continuous stream of foamed cement product and a Mixing and Pump Apparatus, System and an Associated Method for Providing a Stream of Foamed Cement Material wherein the mixing and pumping apparatus including: a continuous mixer adapted to mix a dry feed material with water to provide a cement paste material; a pump assembly including a pump arranged to receive the cement paste material and pump the cement paste material through a cement paste outlet; and a foam generator assembly including a further pump arranged to provide a foaming substance through a foaming substance outlet, wherein the mixing and pumping apparatus includes a control system configured to control the flow of the cement paste and the foaming substance so as to be mixable with one-another to provide a foamed cement product.

Description

A system for providing a continuous stream of foamed cement product and a Mixing and Pump Apparatus, System and an

Associated Method for Providing a Stream of Foamed Cement Material

Technical Field [001] The invention relates to a system for providing a continuous stream of foamed cement product.

[002] The invention relates to a mixing and pump apparatus.

[003] The invention in a particularly preferred form relates to a mixing and pump apparatus, system and associated method for providing a continuous stream of foamed cement material to form a wall or plug seal in an underground environment.

[004] The invention relates to a method for providing a stream of foamed cement material to form a wall or plug seal in an underground environment.

Background [005] Plug seals (also known as monolithic seals) are used in underground coal mining to seal or close a mine tunnel, roadway or shaft. Such plug seals may be formed from variety of methods and typically such methods involve mixing a cement based feed stock with water and a foaming additive to from a foam cement product which is applied in-situ to form the plug seal.

[006] One method of forming a foamed cement product for a plug seal includes using 25kg bags of cement which typically include about 40% Portland cement, 30% aluminum cement and foaming additives that when water is added produces hydrogen bubbles in the mix. The 25 kg bags are opened and tipped manually into the hopper on top of the Langley placer pump. The product runs through a wet ring where it is mixed with water to form a wet cement product. A horizontal auger then feeds it into a wet box where it is pumped by a worm shaft (also known as a screw shaft) arrangement into delivery lines which are arranged to deliver the wet foamed cement product to an emplacement site to form the plug seal. The delivery lines are typically a minimum 60 metres long for gel time and a have a maximum length of 150 metres. The density of the

2018274977 06 Dec 2018 foamed cement product produced falls between about 0.6 to 0.8 S.G (Specific Gravity).

[007] A problem with the above method is that manual handling is required to open and tip the 25kg cement bags into the hopper and dust is produced during this process.

[008] Another problem is that the above method only allows a narrow range of Specific Gravity of the foamed wet cement product.

[009] Another problem with the above method is that wet cement product gels quickly which may block the lines and results in the delivery lines having a limited length of about 150 metres.

[0010] Another problem with the above method is that water has a significant effect on the concrete strength and the compressive strength may be limited in the range of about 2 to 3 mPa.

[0011] Another problem with the above method is the speed of application that limits the tonnes of the foamed cement product that may be produced in a single shift, which in underground mining, may be about 10 hours.

[0012] Another problem can arise when using continuous mixers that are incapable of operating at high speed I RPM. For such mixers, when using 100% Portland cement containing no sands or aggregate, the cement and water mix balls together and blocks the mixer.

[0013] The invention disclosed herein seeks to overcome one or more of the above identified problems or at least provide a useful alternative.

Summary [0014] In accordance with a first main aspect, there is provided a mixing and pumping apparatus including: a continuous mixer adapted to mix a dry feed material with water to provide a cement paste material; a pump assembly including a pump arranged to receive the cement paste material and pump the cement paste material through a cement paste outlet; and a foam generator assembly including a further pump arranged to provide a foaming

2018274977 06 Dec 2018 substance through a foaming substance outlet, wherein the mixing and pumping apparatus includes a control system configured to control the flow of the cement paste and the foaming substance so as to be mixable with one-another to provide a foamed cement product.

[0015] In one aspect, the control system is a hydraulic control system configured to be connectable to an external hydraulic power to hydraulically power and control the continuous mixer, the pump assembly and the foam generator assembly.

[0016] In another aspect, the apparatus further includes a feed conveyor arranged to continuously convey the dry feed material to the continuous mixer, wherein the control system is configured to control the feed rate of the dry feed material from the feed conveyor to the continuous mixer.

[0017] In another aspect, the apparatus is an integral unit including a supporting body having a base supporting the feed conveyor, continuous mixer, the pump assembly, the foam generator assembly and the control system.

[0018] In another aspect, the continuous mixer includes a mixer body arranged substantially horizontally relative to the base, the continuous mixer including a shaft arranged lengthwise along the supporting body, the shaft being driven by a motor to rotate a series of blades carried by the shaft and being configured to mix the dry feed material with the water to provide the cement paste material.

[0019] In another aspect, the mixer body includes a dry feed material inlet, a cement paste outlet and a water inlet between the dry feed material inlet and the cement paste outlet.

[0020] In another aspect, the blades are arranged in a staggered arrangement so as to form a staggered spiral along the length of the shaft between the dry feed material inlet and the cement paste outlet and wherein the blades are angled so as to urge the cement paste material toward the cement paste outlet.

[0021] In another aspect, the water inlet is angled toward the cement paste outlet.

[0022] In another aspect, the mixer body includes a removable cover.

2018274977 06 Dec 2018 [0023] In another aspect, the cover forms an upper half of the mixer body and includes handles.

[0024] In another aspect, the supporting body of the apparatus supports a dry feed material hopper which feeds the feed conveyor.

[0025] In another aspect, the supporting body of the apparatus supports a further hopper located between the continuous mixer and the pump assembly.

[0026] In another aspect, the feed hopper and further hopper are located toward opposing ends of the body relative to one another.

[0027] In another aspect, the pump assembly is located beneath the further hopper.

[0028] In another aspect, a control valve is located between the pump assembly and the cement paste outlet, wherein the control valve in operate commination with the control system so as to control the flow of cement paste product.

[0029] In accordance with a second main aspect, there is provided a system for providing a continuous stream of foamed cement product including: a mixing and pumping apparatus as defined above, and a foam mixer arranged to receive and mix the continuous stream of cement paste and a continuous stream of foaming substance from the apparatus so as to provide the continuous stream of foamed cement product.

[0030] In one aspect, the foam mixer is located remote to the apparatus with a foam substance conduit extending between a foaming substance outlet of the apparatus and a foaming substance inlet of the foam mixer, and a cement paste conduit extending between the cement paste outlet of the apparatus and a cement paste inlet of the foam mixer.

[0031] In another aspect, the foam mixer includes a foam generator in fluid communication with a static mixer, the foam generator including the foaming substance inlet and a foam outlet arranged to deliver a foam product into the static mixer, and wherein the static mixer includes the cement paste inlet, a foamed cement product outlet and baffles arranged to mix the cement paste product and the foam product.

2018274977 06 Dec 2018 [0032] In accordance with a third main aspect there is provided, a method for providing a continuous stream of foamed cement material to form a wall using a system as described above, the method including the steps of: Feeding, at a controlled rate, substantially dry feed cement material to the continuous mixer; Mixing, in the continuous mixer, the dry cement material with water to form the wet mixed cement material or cement paste material; Pumping, via the pump assembly, the wet mixed cement material or cement paste material to the foam mixer; Mixing, in the foam mixer, a foaming substance so as to provide the continuous stream of foamed cement material to form the wall.

[0033] In one aspect, wherein the step of feeding includes feeding the substantially dry feed cement material with a feed conveyer and actuating a control system in communication with the feed conveyer to control a feed rate of the substantially dry feed cement into the continuous mixer.

[0034] In another aspect, the substantially dry feed cement material is at least one of Portland cement type one, Portland cement type two and micro-fine cement, and wherein the foaming substance includes a foaming agent which includes a surfactant.

[0035] In another aspect, the foaming substance includes a mixture of water, air and a forming agent. The foaming substance may include a base foaming agent or concentrate that is mixed with water and air to form the foaming substance.

[0036] In another aspect, the method includes the step of monitoring the specific gravity of at least one of the mixed cement material and the stream of foamed cement material, and controlling at least one of the feed rate of the substantially dry material and a water feed rate into the continuous mixer such that the specific gravity is within a pre-determined range.

[0037] In another aspect, the pre-determined range for the mixed cement material is between a specific gravity of about 1500 to 1800 at which the mixed cement material has a paste like consistency.

[0038] In accordance with a fourth main aspect, there is provided a mixing and pumping system for providing a foamed cement product, the system including: a mixer adapted to mix a dry feed material with water to provide a

2018274977 06 Dec 2018 cement paste material; a pump assembly including a pump arranged to receive the cement paste material and pump the cement paste material through a cement paste outlet; and a foam generator assembly including a further pump arranged to provide a foaming substance through a foaming substance outlet, wherein the mixing and pumping apparatus includes a control system configured to control the flow of the cement paste and the foaming substance so as to be mixable with one-another to provide the foamed cement product.

Brief Description of the Figures [0039] The invention is described, by way of non-limiting example only, by reference to the accompanying figures, in which:

Figure 1 is a diagram illustrating a system including a pumping and mixing apparatus and a foam mixing assembly;

Figure 2 is a schematic process flow diagram illustrating components of the system as shown in Figure 1;

Figure 3 is front or feed end perspective view illustrating the pumping and mixing apparatus;

Figure 4 is rear or discharge end perspective view illustrating the pumping and mixing apparatus;

Figure 5 is a side view illustrating the pumping and mixing apparatus;

Figure 6 is a top view illustrating the pumping and mixing apparatus;

Figure 7 is a front view illustrating the pumping and mixing apparatus;

Figure 8 is an end view illustrating the pumping and mixing apparatus;

Figure 9 is a view of the foam mixing assembly including a static mixer and a foam generator showing internal structure;

Figure 10 is a perspective view of the high-speed mixer;

Figure 11 is a top hidden detail view of the high-speed mixer;

Figure 12 is a side hidden detail view of the high-speed mixer; and

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Figure 13 is a sectional view of the high-speed mixer along section A-A as shown in Figure 12.

Detailed Description [0040] Referring to Figure 1, there is shown a system 5 for use in the underground mining environment to form walls, plugs or seals to close or seal a mining tunnel, roadway or shaft.

[0041] The system 5 includes and utilises a cement mixing unit or apparatus 10 in communication with a remotely located foam mixer assembly 2. The cement mixing unit or apparatus 10 includes a feed assembly 11 including a feed hopper 14 and an auger 18, a mixer 20 in the form of a high-speed continuous mixer 22, and a concrete pump assembly 27 which discharges a concrete paste product, via a concrete paste conduit or line 4, to the foam mixer assembly 2. The system 5 also includes foam conduit or line 7 that communicates a foam generation system 35 (shown in Figure 2) within the apparatus 10 with the foam mixer assembly 2. The foam mixer assembly 2 includes a foam generator 8 that discharges into a static mixer 9. The concrete paste line 4 is coupled to the static mixer 9 and mixes with a foaming agent or substance to form a foamed cement product that is discharged from an outlet or nozzle 3 of the static mixer 9.

[0042] Referring now additionally to Figure 2, the system 5 includes a dry feed material delivery arrangement 11 for feeding dry feed cement material to the mixer 20 in the form of the high-speed continuous mixer 22. The dry feed material delivery arrangement 11 may include feeding the high-speed mixer 22 directly from a bulk bin feeder system 21 or feeding material into a feed hopper 14, and then via a materials transport apparatus 16 in the form of an auger 18 (also known as a screw conveyor) which coveys, elevates and delivers the feed material to the high-speed mixed 22.

[0043] The bulk bin feeder system 21 may have an integrated auger (not shown) which discharges directly to the high-speed mixer 22. The bin system 21 may be filled with dry cement product and transported to the pump site and positioned over the mixer 22. In this example, the feed hopper 14 is utilised and may be fed by hand loading bags 13, by machine fed bag system

2018274977 06 Dec 2018 or by bulk bag feed system 17. In either system, the auger 18 or integrated auger (as shown in Figure 3) is controlled by the cement mixing unit or apparatus 10 that has a hydraulic power and control system 40 as is further detailed below.

[0044] The dry feed material, water and additive, if required, are fed into the continuous mixer 22 that spins mixing paddles to mix the product and ejects a mixed cement slurry or paste product to a further hopper 24. The continuous high-speed mixer 22 accepts input water from a mix water supply 29. The continuous high-speed mixer 22 is controlled and powered by the hydraulic power and control system 40 as is further detailed below. The further hopper 24 accepts the mixed cement paste product from the high-speed mixer 22 before the mixed cement paste product enters the pumping stage. The further hopper 24 may be a standard collection hopper or any collection point for the slurry so that it can then be pumped. No sooner than the slurry goes in to hopper 24 it may be pumped out, without a settling period allowed for, all the while maintaining a certain level of slurry in the hopper 24 so that air is not pumped through the system.

[0045] The pumping stage includes a swing tube valve unit 26 and a concrete pump assembly 27. The concrete pump assembly 27 may include a twin cylinder double acting reversible concrete pump or a squeeze pump unit (peristaltic) that is mounted within the cement mixing unit or apparatus 10. The concrete pump assembly 27 is controlled and powered by the hydraulic power and control system 40 as is further detailed below. The concrete pump 27 discharges the mixed concrete slurry or paste product to the paste conduit or line 4 (shown in Figure 1) to the static mixer 9 which is used to mix the mixed concrete slurry product with foam from the foam generation system 35. The static mixer 9 then discharges a final aerated or foamed cement product for forming the wall, plug or seals as required.

[0046] The foam generation system 35 includes a single or double hydraulic motor 37 which drives a water pump 39 and foaming agent pump 41 at the same time or simultaneously. The water pump 39 and foaming agent pump 41 are sized to output the correct ratio of water and foaming agent at any speed.

2018274977 06 Dec 2018

The foam-generating pump has on/off and speed controls on the operators panel 53 (as shown in Figure 5). Compressed air 43 is injected into the water/foam mix when it leaves the pumps 39, 41. The compressed air 43 is controlled and powered by the hydraulic power and control system 40 as is further detailed below. The water pump 39 may be connected to the water supply 29 and the foaming agent pump 41 may be connected to the foam agent supply 33 which may include a base or concentrate foaming agent including a surfactant. The water supply 29 and foam agent supply 33 may be tanks outside or inside the apparatus or unit 10. In this example, the apparatus 10 includes a tank beneath the foaming agent pump 41. A suitable foaming agent may be a Magna™ foam concentrate commercially available from Cellcete Technologies Inc™. The quantity to be added to the cement paste may be in accordance with manufactures specifications, the water dilution, the specific application and the specific gravity of the final foamed cement product.

[0047] The foam generation system 35 provides a foaming substance including a mixture of the water, the foaming agent and the air mixture. The foaming substance is pumped through the line 7 to the foam injection unit or foam generator 8 that aids the mixing of the foaming substance (which includes water, foaming agent and air) to cause an expansion of the mixed product into a foam like consistency. The water, foaming agent and air mixture may be referred to as a foaming agent mixture or simply a foaming substance that is delivered to the foam generator 8.

[0048] Once foamed, the foamed foaming substance product then leaves the foam injection unit 8 and is piped directly into the static mixer 9 where it is mixed with the cement slurry or paste material being pumped via the cement paste conduit 4 from the main concrete pump assembly 27 mounted in the main unit

10. This forms an aerated foamed cement product which is then piped from the static mixer 9 to the emplacement site to form the wall, plug or seal as required.

[0049] Referring additionally to Figures 3 to 8, an example of a cement mixing unit or apparatus 10 is now described in further detail.

[0050] The cement mixing unit 10 includes a supporting frame or body 12

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2018274977 06 Dec 2018 which supports or houses the feed hopper 14, the auger 18 (as known as a screw conveyor), the high-speed continuous mixer 22, the further hopper 24, the valve unit 26, the concrete pump assembly 27, the foam generation system 35, the hydraulic power and control system 40 and the services connectors.

[0051] The hydraulic power and control system 40 includes a hydraulic manifold 51 and a control panel 53 (shown on Figure 3) which is operable by a user to control the pump and mixing unit 10. The hydraulic power and control system 40 is coupled to the components and parts that require power such as the auger 18, mixer 20 and concrete pump assembly 27 (as is shown by dashed lines in Figure 2). The hydraulic power and control system 40 is connected to an external hydraulic supply service 31 (shown on Figure 2). The services connectors are water supply in, compressed air supply in, hydraulic supply in, hydraulic return out as shown on Figure 2.

[0052] The supporting frame or body 12 includes a base skid 28 having apertures 30 therein arranged to receive forks of a forklift (or similar machine) for moving the cement mixing unit 10. Covers or body plates 23 are also fitted to at least partially enclose the supporting frame or body 12. Accordingly, the unit 10 may be readily transported as a complete or integral skid mounted unit. The supporting frame 12 is designed to comply with the required MDG (Mining Design Guidelines) guidelines and standard engineering practices. The body 12 is generally formed from mild-steel. The body 12 has an overall length and width with suitable for passage along and manoeuvring within a mineshaft, tunnel or road. The body 12 width being suitably narrow for carriage by a forklift.

[0053] The feed hopper 14 is located toward a first end 32 of the cement mixing unit 10 and is arranged receive and temporarily store the feed material, which may be in the form of dry cement material and the auger 18 is configured to transfer the feed material to the high-speed mixer 22. In this example, the feed hopper is generally rectangular in shape and has a capacity of about 80kg.

[0054] The auger 18 includes a motor 19 powered and controlled by the hydraulic power and control system 40. In this example, the motor 19 is a 160cc (cubic centimetre) Gear Motion hydraulic type motor. In this example, the

2018274977 06 Dec 2018 auger 18 has a capacity of about between about 10 tonnes per hour.

[0055] The auger 18 spans and is angled upwardly from the first end 32 to a second opposing end 34 of the cement mixing unit 10. Accordingly, the auger 18 raises the feed material and then delivers the feed material into the highspeed mixer 22 that is positioned below the auger 18. The auger 18 has controls, located on the control panel 51 including on/off, forward/reverse and feed rate control. The auger 18 motor is connected, via the hydraulic power and control system 40, to the pump assembly 27 for feed rate control.

[0056] The high-speed mixer 22 is located in an elevated position, relative to the feed hopper 14 and concrete pump assembly 26, located at the second end 34 of the cement-mixing unit 10. The high-speed mixer 22 is configured to mix the dry feed material with water and, if required further additives, to form a cement slurry or paste material. The high-speed mixer 22 includes a barrel shaped body 36 arranged transverse to the auger 18 and spanning generally horizontally between opposing sides 38 of the cement-mixing unit 10 and a shaft 60 (shown in Figure 11) which carries rotating mixing blades or paddles 63 (shown in Figure 11) extending lengthwise along the barrel shaped body 36.

[0057] The shaft 60 is driven by a mixer motor 65 to continuously rotate the shaft 60 and paddles 63 within the barrel shaped body 36. The high-speed mixer 22 includes an inlet end 61 located toward one of the opposing sides 38 which receives the dry cement feed material and water, and an outlet or discharge end 62 located toward an opposing one of the sides 38. The highspeed mixer 22 is powered and controlled by the hydraulic power and control system 40. The high-speed mixer on/off, forward/reverse, speed and water supply is controlled from the control panel 51. The high-speed mixer 22 discharges via the discharge end 62 directly via gravity into the further hopper 24 located below the discharge end 62.

In this example, the mixer 22 is sized to handle a cement slurry paste having a specific gravity of between about 1600 sg to 1800 sg (specific gravity) and to 3 3 provide an output capacity of between about 1 m per and hour 6m per hour. The motor 65 is a 12.5cc (cubic centimetre) Gear Motion hydraulic type motor. The motor 65 drives the shaft at about between 1 rpm and 1000 rpm

2018274977 06 Dec 2018 (revolutions per minute). The mixer 22 may be formed from CM1000 model mixer in which the auger section is removed and replaced with additional mixing blades available from Warill Engineering Sales™ or similar manufacturers. The mixer 22 is described in further detail below with reference to Figures 10 to 13.

[0058]The further hopper 24 discharges to the swing tube valve unit 26 which is located directly beneath the further hopper 24. The swing tube valve unit 26 controls the entry and exit from the concrete pump assembly 27. The swing tube valve unit 26 may be a Transcrete™ brand Alpha S Tube.

[0059] In this example, the concrete pump assembly 27 may include twin cylinder double acting reversible concrete pumps 67 arranged lengthwise between first 32 and second 34 ends of the body 12. The concrete pump assembly 27 is controlled from the control panel 51 and has variable speed, forward/reverse and on/off control. The pump assembly 27 discharges via concrete slurry discharge 69 which then proceeds via the slurry line 4 to the static mixer 9. The static mixer 9 is located remotely to the unit 10. The pump 3 3 assembly 27 has a capacity of about 1 m per hour to 20m per hour. An example of a suitable pump 67 is a Putzmeister™ TK15.

[0060] The apparatus or unit 10 also houses the foam generation system 35 including the single or double hydraulic motor 37 which drives the water pump 39 and foaming agent pump 41. The hydraulic motor 37 and compressed air 43 delivery are controlled via the control panel 51. The foam generation system 35 discharges via a foam discharge 71 via the foam conduit or line 7 to the foam generator 8 of the foam mixer assembly 9 that is located remotely to the unit 10. The hydraulic motor 37 may be a 26cc Gear Motor such as a Boden™ HP-2AOD, the water pump 39 and foaming agent pump 41 are each Boden™ BKBO5A100 pumps which have a capacity of 25cc. Such pumps are commonly available.

[0061] Turning to the hydraulic power and control system 40 in more detail, the hydraulic power and control system 40 is coupled to an external compatible hydraulic pump (not shown), connected by suitable hydraulic hoses supplying at least 105 LPM (Litres per Minute) at 120 Bar pressure. The hydraulic power and

2018274977 06 Dec 2018 control system 40 includes isolating valves (not shown) mounted inside the body 12 and an oil filter (not shown). Hydraulic supply continues from the isolating valve the control panel valve bank or manifold which controls the following functions: Feed Auger Motor 19 which is a 160cc Gear Motion motor; Highspeed Mixer Motor 65 which is a 12.5cc Gear Motor & Lube Unit; Swing Tube 26 Valve Cylinders; Concrete Pump 67 Cylinders; Water/Foaming Pump Motor 37 which is a 26cc Gear Motor. The return Hydraulic oil is returned to the external compatible hydraulic pump unit via a return line oil-cooling unit.

[0062] The control panel 51 has hydraulic pressure gauges and water flow meters to monitor the unit or machine 10 status and assist the operator. The control panel 51 also includes a series of hand operable levers and dials which are coupled to an actuate the valves of the control panel valve bank to control the motors and pumps of the apparatus 10 as described above. Such hydraulic control arrangements are well known and are not further detailed herein.

[0063] Referring now to Figure 9, an example of the foam mixer assembly 2 is shown. The foam mixer assembly 2 includes the foam generator 8 that discharges into the static mixer 9. The static mixer 9 includes a cylindrical body 80 including an inlet end 81, an outlet end 82 and internal fixed mixing plates or baffles 84 arranged to providing mixing of the cement paste product and the foaming substance. The foam generator 8 includes an inlet end 86 coupled to the foam line 7 and an outlet end 88 coupled to the static mixer 9 toward or at the inlet end 81 of the static mixer 9. The foam generator 8 includes a generally cylindrical body 90 extending between the inlet end 86 and the outlet end 88, and an arrangement internal ceramic apertures or donuts 92 configured to assist foam generation.

[0064] Referring now to Figures 10 to 13, the continuous high-speed mixer 22 is described in further detail. The barrel shaped mixer body 36 is formed in two halves with the upper half being a removable section 66 extending along the length of the mixer body 36 and the lower half being a fixed section 64. The removable section 66 includes handles 67 for removal and carriage of the removable section 66 and flanges 68 extending along opposing sides thereof for

2018274977 06 Dec 2018 coupling, via fasteners 69, with a corresponding flanges 70 of the fixed section 64.

[0065] The mixer body 36 includes two spaced apart water inlets 71 which are angled such that the water enters the mixer body 36 co-current or in the direction of the material flow. The water inlets 71 are located on the lower fixed section 64 and are about intermediate the cement inlet 61 and product outlet 62 of the mixer 22.

[0066] Turning now to the shaft 60 and paddles or blades 63 in more detail. The mixing blades 63 are arranged in a dual start spiral arrangement designed to give a cross mixing action. The blades 63 are arranged to extend radially from the shaft 60 and terminate just short of the inner walls 75 of the mixer body 36. Each of the blades 63 includes a blade body 72 which is coupled to and angled relative to the shaft 60 to provide forward motion and urge the cement paste product from the inlet 61 to the outlet 62. The blade body 72 is coupled to the shaft 60 via adjustable couplings 76 that is configured to allow the pitch or angle of the blades 63 to be adjustable to provide variation to suit the requirements of the material being mixed.

[0067] The tips 73 of the blades 63 are curved to clear and fit with the inner walls 75 of the mixer body 36. The blades 63 are generally spaced apart along the shaft 60 with alternating blades 63 being at 90 degrees to one another along the length of the shaft 60. Accordingly, the mixing blades 63 are arranged in a dual start spiral arrangement designed to give a cross-mixing action whist urging the mixing cement paste product toward the cement paste outlet 62.

[0068] Advantageously, the unit or apparatus 10 is compact and may be easily moved around the underground coalmine environment. The unit 10 is safe to use in a hazardous environment according to Australian coal mining guidelines and may be powered from various types of hydraulic power supplies. The unit 10 is operated from the control panel 53 thus removing the operator from possible interaction with machinery.

[0069] Further advantageously, the unit 10 is designed to continuously mix and supply cement-based products through the high-speed continuous mixer thus allowing the process to continue without the needed to stop the process to

2018274977 06 Dec 2018 makes fresh batches of cement. This also means that wastage is minimal, as excess batch product is not wasted. In particular, the use of the high-speed mixer with internal paddles having a high-speed of rotation the unit 10 is able to provide a well-mixed product in a compact unit. The unit 10 capable of changing the mix density (specific gravity) whilst in operation and allows for on-site changes to the product supplied.

[0070] In use, the system 5 including the unit 10 and the static mixer 9 are typically located underground and near to the wall, plug or seal that is to be formed. The distance between the unit 10 and the wall, plug or seal that is to be formed may be 1 to 1000m depending on the length of the supply lines. The cement slurry line and the foam mix line are each connected from the pump unit 10 to the static mixer 9. The static mixer 9 is located proximate to or near to the wall, plug or seal that is to be formed.

[0071] Once the system 5 is in place, the unit 10 is coupled to the required hydraulic, water and pneumatic services. A method to operate the system 5 is as follows. The water supply valve on the unit 10 is opened and set via the control panel 51 to the recommend flow rate, which may be between about 1

3 m per hour to 6 m per hour. The water is allowed to flow through to the main discharge hopper 24. Once the water flow rate has been achieved, the control panel 51 is actuated by a user to activate the high-speed mixer 22. The pitch of the blades 63 is adjustable to provide variation to suit the requirements of the material being mixed.

[0072] The control panel 51 is then used to set the overall feed rate of the feed material via the motor speed of the auger. The dry feed material may be Portland cement type one & two or micro-fine cement and the foaming agent may be a synthetic surfactant with a density range of product 450 sg to 1500 sg. In some example, fibres may be added to the dry feed material to change the end product properties to suit requirements.

[0073] The dry feed material is then introduced into the feed hopper 14 and conveyed by the auger 18 into the high-speed mixer 22 where it is mixed with water to form the slurry paste cement product. The speed of the auger 18 is increased or decreased to adjust the flow of the dry feed material into high-16

2018274977 06 Dec 2018 speed mixer 22 until the desired specific gravity or density weight is reached. The specific gravity may be measured from weighting a 1 litre of the product with scales, for example, if the 1 litre container weighs 600grams you have 600kgs/m3. Preferably, the auger speed is adjusted to obtain a cement paste with a 1500 sg to 1800 sg (specific gravity). It is noted that the speed of the mixer 22 may be adjusted via the motor speed of the mixer and the feed rate of the water into the mixer 22 may also be adjusted as required.

[0074] Once the desired specific gravity or density weight of the cement slurry has been achieved, the main concrete pump 27 is then activated with the control panel 51 to commence pumping the cement slurry product to the static mixer 9. The foaming system 35 is then also activated in conjunction with the air supply from the control panel 51. Once the foam is injected into the concrete slurry, re-calibration of the desired specific gravity or density weight will have to be repeated. This may be sampled from the main delivery hose coupled to the output 82 of the static mixer 9. Once desired density has been reached the pumping is continued until completion of task.

[0075] The above described system 5, apparatus or unit 10 and method of operation allow for the following advantages:

• Plug seals can now be made between 30 to 60% cheaper due to cheaper raw materials and less labor required to operate. The materials may be cheaper because the cement feed material does not essentially require a foaming additive as is the case with existing systems;

• OH & S issues solved - Reduction and elimination of manual handling tasks by use of the pumps interaction with machinery. Massive reduction in dust make due to all processes being enclosed.

• Quality control issues - Other methods of producing lightweight products require very strict quality control regimes as product ratio content greatly affects the final strength. In contrast, the above-disclosed method is only slightly affected and is easily monitored by weight of the product. The mix may be adjusted to adapt to individual project requirements.

• Handling mine water issues during construction. The density of the cement product may be changed on “the run”. This enables us the option to

2018274977 06 Dec 2018 adjust the specific gravity of the mix and control the water make. It is noted that know methods may not be able to be installed in a wet environment.

• The concrete product mix (specific gravity) may be adjusted to individual • project requirements allows the mine site significant savings as the ventilation devices, seals and bulkheads. The system 5 or unit 10 may be used in conjunction with the mine strata control plan and eliminate additional costly strata control mechanisms that the mine site would otherwise need to install using other ventilation control devices.

[0076] Throughout this specification and the claims which follow, the term “wall” is intended to mean any wall like structure formed in an underground environment including plug seals (also known as monolithic seals) used in underground coal mining to seal or close a mine tunnel, roadway or shaft.

[0077] Throughout this specification and the claims which follow, unless the context requires otherwise, the word comprise, and variations such as comprises and comprising, will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

[0078] The reference in this specification to any known matter or any prior publication is not, and should not be taken to be, an acknowledgment or admission or suggestion that the known matter or prior art publication forms part of the common general knowledge in the field to which this specification relates.

[0079] While specific examples of the invention have been described, it will be understood that the invention extends to alternative combinations of the features disclosed or evident from the disclosure provided herein.

[0080] Many and various modifications will be apparent to those skilled in the art without departing from the scope of the invention disclosed or evident from the disclosure provided herein.

Claims (9)

1. The claims defining the invention are as follows:

   1. A compact integral mixing and pumping unit suitable for use in an underground mining tunnel, roadway or shaft, for providing a continuous stream of cement paste material and a continuous stream of foaming substance that are mixable via a remote foam mixer assembly communicable with the mixing and pumping unit to provide a continuous stream of foam cement product, the mixing and pumping unit including:

   a. a feed hopper arranged to receive a dry cement feed material;

   b. a high-speed continuous mixer adapted to mix the dry cement feed material with water to provide the continuous stream of cement paste material; wherein the continuous mixer includes a mixer body, a dry feed material inlet, a cement paste outlet, a water inlet, and a shaft arranged along the mixer body, the shaft being driven by a motor at high speed to rotate a series of blades carried by the shaft that are configured to mix the dry cement feed material with the water to provide the continuous stream of cement paste material

   c. a feed conveyor arranged to convey the dry cement feed material from the feed hopper to the continuous mixer;

   d. a further hopper arranged to receive the continuous stream of cement paste material from the continuous mixer;

   e. a concrete pump assembly including a pump arranged to receive the continuous stream of cement paste material from the further hopper and pump the cement paste material through a cement paste outlet for subsequent mixing by the remote foam mixer assembly;

   f. a foaming substance assembly for providing the foaming substance as a mixture including water, foaming agent and/or air, the foaming substance assembly including a further pump arranged to

   2018274977 06 Dec 2018 provide the continuous stream of foaming substance through a foaming substance outlet for subsequent mixing by the remote foam mixer assembly;

   g. a control system configured to control the flow of the continuous stream of cement paste material and the continuous stream of foaming substance so as to be mixable via the foam mixer assembly to provide the continuous stream of foamed cement product; and

   h. a supporting frame or body comprising a base adapted to support the feed hopper, the continuous mixer, the feed conveyor, the further hopper, the pump assembly, the foaming substance assembly and the control system so as to be moveable as an integral unit, the frame or body having an overall length and width suitable for passage along and manoeuvring within the underground mining tunnel, roadway or shaft.
2. 2. The mixing and pumping unit according to claim 1, wherein the continuous mixer is elevated relative to the further hopper such that the continuous stream of cement paste material is dischargeable via gravity from the continuous mixer to the further hopper.
3. 3. The mixing and pumping unit according to claim 1 or claim 2, wherein the mixer body is arranged substantially horizontally relative to the base, and the shaft is arranged lengthwise along the mixer body.
4. 4. The mixing and pumping unit according to any one of the previous claims, wherein the water inlet is angled such that the water is directed toward the cement paste outlet, and wherein the blades are arranged to form a staggered spiral along the length of the shaft between the dry feed material inlet and the cement paste outlet and, wherein the blades are angled so as to urge the

   2018274977 06 Dec 2018 continuous stream of cement paste material toward the cement paste outlet.
5. 5. The mixing and pumping unit according to any one of the previous claims, wherein the control system includes a hydraulic control system configured to be connectable to an external hydraulic power source to hydraulically power and control the continuous mixer, the feed conveyor and the foaming substance assembly, and wherein the control system is configured to control the feed rate of the dry cement feed material from the feed conveyor to the continuous mixer thereby enabling the specific gravity of the continuous stream of cement paste material to be controllable.
6. 6. The mixing and pumping unit according to any one of the previous claims, wherein the feed conveyer comprises an auger which is angled upwardly from the feed hopper, the auger being arranged to convey, elevate and deliver the feed material to the high-speed mixer, which high-speed mixer is positioned below the auger.
7. 7. The mixing and pumping unit according to any one of the previous claims, wherein the base has apertures therein arranged to receive forks of a forklift or similar machine for moving the cement mixing unit.
8. 8. The mixing and pumping unit according to any one of the previous claims, wherein the dry cement feed material consists of at least one of Portland cement type one, Portland cement type two and micro-fine cement.
9. 9. The mixing and pumping unit according to any one of the previous claims, wherein the foaming substance mixture consists of water, foaming agent and air.