AU2016262764B2

AU2016262764B2 - Improved sampling apparatus and method

Info

Publication number: AU2016262764B2
Application number: AU2016262764A
Authority: AU
Inventors: Colin Howard
Original assignee: Oscillation Pty Ltd
Current assignee: Oscillation Pty Ltd
Priority date: 2016-11-25
Filing date: 2016-11-25
Publication date: 2021-08-12
Anticipated expiration: 2036-11-25
Also published as: AU2016102043A4; AU2016262764A1; AU2016102042A4

Abstract

The invention provides generally a method for analysing a high density tailings feed of a mechanical dewatering system, the method comprising the steps of: opening a process valve, thereby to permit fluid communication of the tailings feed to a control apparatus; analysing the flocculation and coagulation characteristics of the tailings feed within the control apparatus to give rise to scatter output; communicating the scatter output to a control panel associated with a flocculant pump and a coagulant pump; comparing the scatter output with user-defined reference values for flocculation and coagulation; and adjusting the dosage levels of the flocculation and coagulation pumps accordingly such that a defined amount of flocculant and/or coagulant is then provided to the mechanical dewatering system based upon an algorithm relating the ratio of scatter number to the reference value. (Figure 4) -4/4 .. .. ... .. .---.. . . --- --- -- --- --- -- --- -- --- --- -- --- --- -N--- - -------- N \ N /Wx 4/4 ......... ... N FI'UR 4"

Description

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IMPROVED SAMPLING APPARATUS AND METHOD

Field of the Invention The present invention relates to a device and method for the determination of the rate of sedimentation of particles in a sample of a liquid and controlling the addition of a flocculant to a body of the liquid from which the sample was drawn in accordance with the sedimentation rate so determined. In preferred embodiments, the invention relates to an apparatus and method for obtaining a sample volume of a liquid. The inventive system monitors high density tailings rather than predominantly liquid slurries. Previously, the various capture techniques resulted in a fixed volume of sample and examined the settling characteristics under gravity. In the present invention, a sample is spread on the scatter plate and the chemical flocculation reaction is examined; there remains a gravity component. More particularly, the present invention has been designed for continual online analysis of the tailings feed from mechanical dewatering systems such as belt press filters and centrifuges. From this analysis, the chemical addition to the tailings is automatically controllable. Other features of the system are that it is safe, non-intrusive and self-cleaning. Most importantly, the inventive system stands to optimise and reduce chemical usage. It may also eliminate the requirement for operators to continually check tailings quality for the manual adjustment of the chemical pass.

Background of the Invention Any discussion of the prior art throughout the specification should in no way be considered as an admission that such prior art is widely known or forms part of common general knowledge in the field. Many processes require a sample volume of liquid to be obtained from a larger body of that liquid for analysis. From the analysis of the sample volume calculations can be undertaken to determine/estimate the properties of the liquid in the larger body. There are many occasions in the mining industry, in agriculture and in waste water treatment (indeed, any industry utilising flocculants and coagulants - such as paper, plastics and sewage) when it is necessary to separate fine particulate matter from a body of a liquid such as water. This is often achieved by a process of sedimentation or settling. The rate of sedimentation of particles is partly dependent upon their mass and it is therefore advantageous in many cases to add a flocculant to the body of water to induce the fine particles to aggregate or "floc" together. This increases the mass of the particles and hence their sedimentation rate. As flocculant chemicals are expensive and as there may be adverse environmental effects from excessive flocculant addition, it is both environmentally and economically desirable to add only sufficient flocculant to the body of liquid to impart the desired rate of sedimentation to the particles in the liquid. It is known to periodically measure the sedimentation rate of particles in a body of a liquid and to control the rate of addition of the flocculant to the body of liquid in accordance with the rate of sedimentation of the particles. If the particles are not sedimenting at the desired rate then more flocculant is added. If the particles are settling faster than is required then the addition of flocculant may be slowed or stopped completely. In known devices for such purpose a sample of the liquid is drawn up into a sample container by the induction of a reduced pressure in the sample container. Once the liquid level in the container has reached a desired level a pinch valve in the lower end of the sample tube is closed and the vacuum applied to the sample container is released. The pinch valve serves to hold the liquid level constant in the sample container until the rate of sedimentation of the particles in the liquid has been determined. The pinch valve is then opened to release the sample from the sample container and to allow it to flow back into the body of the liquid. It has been considered necessary by those working in the field to use a pinch valve or some similar mechanical valve means to hold the sample in the sample container. This perception is based on the need to hold the level of the liquid in the sample container with absolute certainty. If the level of the sample in the sample container were allowed to drop over the period during which the sedimentation measurements were taking place, the accuracy of the measurement would be seriously compromised. The use of such a mechanical valve, however, has a number of disadvantages. It has in fact proven difficult to provide a guaranteed seal in the pinch valve despite substantial efforts over many years to provide a satisfactory mechanical seal. The vibration caused by the opening and closing of the pinch valve have been found to adversely affect electronic control equipment associated with the device. It has also been found that in the field where the valve is required to open and close many times each day for years on end the deterioration of the components of the valve parts present a serious maintenance load. In previous work, the present inventor found that the presence of a pinch valve or some similar mechanical valve at the bottom of the sample container is, in fact, not necessary. This inventor then surprisingly found that it is possible to hold the sample in the sample container with an acceptable accuracy merely by holding the reduced pressure above the sample for the duration of the period during which the sedimentation rate of particles in the sample is determined. This approach substantially reduces the cost of the device and avoids many of the problems associated with the prior art arrangements. In order to obtain an accurate measure of the rate of sedimentation the sample must be taken carefully, that is without undue turbulence, to avoid damaging the sample (i.e., by breaking up the aggregated particles), which could lead to skewed calculations. Further, regular samples are taken to enable real-time information relating to the rate of sedimentation, to enable the amount of flocculant to be added to be adjusted as the characteristics of the inflow stream vary. It is an object of the present invention to overcome or ameliorate at least one of the disadvantages of the prior art, or to provide a useful alternative. It is an object of an especially preferred form of the present invention to provide for a system the enables continuous online monitoring of the tailings feed to mechanical dewatering systems. Ideally, the system is safe, non-intrusive and self-cleaning. Most desirably, it may stand to optimise and reduce flocculant usage. Even more preferably, the inventive system may stand to eliminate the labour and time requirement for operators to continually check tailings quality for the manual adjustment for the chemical dosing pumps. Unless the context clearly requires otherwise, throughout the description and the claims, the words "comprise", "comprising", and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is to say, in the sense of "including, but not limited to". Although the invention will be described with reference to specific examples it will be appreciated by those skilled in the art that the invention may be embodied in many other forms.

Summary of the Invention The present invention relates to an apparatus and method for obtaining a sample volume of a liquid. The inventive system monitors high density tailings rather than predominantly liquid slurries. Previously, the various capture techniques resulted in a fixed volume of sample and examined the settling characteristics under gravity. In the present invention, a sample is spread on the scatter plate and the chemical flocculation reaction is examined; there remains a gravity component. The inventive system is defined by three physical components: Firstly, the main control apparatus and the associated drainage tray; secondly, the operator control panel, which houses both the operator touch screen and the PLC; and thirdly, the control valve assembly which comprises the main process valve, the water valve and the specially manufactured live connection piece. Each of these will be explained in the ensuing description, below. According to a first aspect of the present invention there is provided a method when used for analysing a tailings feed having an elevated concentration of dispersed particles therein of a mechanical dewatering system, the method comprising the steps of: opening a process valve, thereby to permit fluid communication of the tailings feed to and across a scatter plate of a control apparatus; analysing the flocculation and coagulation characteristics of the tailings feed as it spreads across the scatter plate by obtaining a monochromatic image of the tailings feed, counting the pixels in the image and applying an algorithm to give rise to a scatter number; communicating the scatter number to a control panel associated with a flocculant pump and a coagulant pump; comparing the scatter number with user-defined reference values for flocculation and coagulation; and adjusting the dosage levels of the flocculation and coagulation pumps accordingly such that a defined amount of flocculant and/or coagulant is then provided to the mechanical dewatering system based upon the scatter number. In an embodiment, the tailings feed is returned to the mechanical dewatering system following analysis, by way of a drainage tray in fluid communication with the mechanical dewatering system. In an embodiment, the analysis is substantially continuous. In an embodiment, the method further comprises a washing step, wherein the control apparatus and associated conduits are periodically flushed with water. In an embodiment, the washing step is associated with a water valve and an air solenoid in fluid communication with a water source. The inventive method is substantially as herein described with reference to any one of the embodiments of the invention illustrated in the accompanying drawings and/or examples. According to a second aspect of the present invention there is provided an apparatus when used for analysing a tailings feed having an elevated concentration of dispersed particles therein of a mechanical dewatering system, the apparatus comprising: means for opening a process valve, thereby to permit fluid communication of the tailings feed to and across a scatter plate of a control apparatus; means for analysing the flocculation and coagulation characteristics of the tailings feed as it spreads across the scatter plate by obtaining a monochromatic image of the tailings feed, counting the pixels in the image and applying an algorithm to give rise to a scatter number; means for communicating the scatter number to a control panel associated with a flocculant pump and a coagulant pump; means for comparing the scatter number with user-defined reference values for flocculation and coagulation; and means for adjusting the dosage levels of the flocculation and coagulation pumps accordingly such that a defined amount of flocculant and/or coagulant is then provided to the mechanical dewatering system

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based upon the scatter number. The analysis step is performed using a novel camera technique. A digital camera is mounted adjacent a scatter plate, and is used to produce a monochrome image of the tailings as they spread out across the scatter plate. In certain forms, the monochrome image may be up to 350,000 pixels in resolution. The pixels are then counted according the sample and divided down to give practical number between 1 and around 275; this is colloquially termed the "scatter number". The scatter number is then correlated against known/measured standards, and the output determined against such standards. Because the inventive system monitors high density tailings, whereas known systems monitor predominantly liquid slurries, this analytical technique is both novel and inventive. In an embodiment, the apparatus further comprises means, in the form of a drainage tray in fluid communication with the mechanical dewatering system for returning the tailings feed to the mechanical dewatering system following analysis. In an embodiment, the analysis is substantially continuous. In an embodiment, the means for analysing the flocculation and coagulation characteristics of the tailings feed relates optical characteristics of the tailings feed with predetermined standards, thereby to determine the dosage levels of the flocculation and/or coagulation pump/s. In an embodiment, the analysis relates optical characteristics of the tailings feed with predetermined standards, thereby to determine the dosage levels of the flocculation and/or coagulation pump/s. In an embodiment, the apparatus further comprises means for effecting a washing step, wherein the control apparatus and associated conduits are periodically flushed with water. In an embodiment, the means for effecting the washing step is associated with a water valve and an air solenoid in fluid communication with a water source. In an embodiment, the inventive apparatus is substantially as herein described with reference to any one of the embodiments of the invention illustrated in the accompanying drawings and/or examples. The present invention consists generally in a three-way relationship between the following three components: the sample apparatus, which provides a means of continually monitoring the effect of chemical dosing levels of the tailings feed to mechanical dewatering systems such as belt press filters and centrifuges. By analysing the tailings, the flocculent and coagulant pumps can be closely controlled; the process valve, in which a sample from the tailings line is fed into the sample apparatus where the chemical reaction is examined. This is a new technique, with the measurement referred to as "sample scatter". The process sample line is flushed after each operation; and the control panel, which is mounted adjacent the sample apparatus and includes a touch screen interface. Three 4-20 mA signals (flocculant and coagulation pumps plus sample scatter) are produced for monitoring and control by the plant supervisory system. By this arrangement, through analysing the tailings, the flocculent and coagulant pumps can be closely controlled. In other forms, the present invention relates generally to a device for the determination of the rate of sedimentation of particles in a sample of a liquid and controlling the addition of a flocculant to the liquid in accordance with the rate of sedimentation so determined; the rate of sedimentation being so-determined by the inventive sampling process as opposed to manual sampling, as has characterised the prior art. The device comprises a sample container, an inlet duct in fluid communication with the sample container and extending downwardly from a lower end thereof and adapted to extend into a body of liquid to be sampled, suction means in fluid communication with an upper end of the sample container and adapted to create a reduced pressure in the sample container such that a sample of the liquid is drawn into the sample container, means to measure the rate of sedimentation of particles in the liquid sample, flocculant addition means adapted to add flocculant to the body of liquid from which the sample was drawn and means adapted to control the addition of flocculant from the flocculant addition means into the body of liquid in accordance with the rate of sedimentation (determined as a result of the inventive process) of the particles in the liquid sample, the device being characterised in that the sample container and the suction means are adapted to hold the sample within the sample container, while the rate of sedimentation of the particles is determined analytically, by maintenance of the reduced pressure in the sample container above the liquid sample. In another form, the present invention relates generally to a process for controlling the sedimentation of particles in a body of a liquid comprising the steps of drawing a sample of the liquid into a sample container through an inlet duct in fluid communication with a lower end of the sample container and with the body of liquid by the creation of a reduced pressure in the sample container, analytically determining the rate of sedimentation of particles in the sample and controlling the addition of flocculant from a flocculant addition means into the body of liquid in accordance with the rate of sedimentation of the particles in the sample, the process being characterised in that the sample is retained in the sample container throughout the determination of the sedimentation rate of particles in the sample solely by maintenance of the reduced pressure in the sample container above the sample. The device and process according to the invention may be applied to controlling the clarification of water in a wide range of industries including mining, agriculture and sewage treatment. It is particularly useful in coal washeries in which coal washwater is admitted to a thickener to induce settlement of the very fine coal and gangue particles entrained in the washwater. Once it has been clarified the washwater may be recycled through the coal washery while the fines settled out of the washwater are disposed of into tailing dams or stockpiles. Prior to the development of the present invention, the rate of sedimentation of the particles was carried out manually. One suitable manual means includes a light disposed on one side of the sample container and a photoelectric cell disposed in the path of the light on the other side of the sample container. A timer is actuated as soon as a sample reaches a desired level in the sample container and is stopped when the particles in the container have settled to a level which allows the light to pass through the container and the liquid therein sufficiently to be registered by the photoelectric cell. The rate of addition of the flocculant to the body of the liquid was then controlled in accordance with an algorithm based on the time recorded on the timer. The suction means comprised an air pump or vacuum generator which created a reduced pressure in the sample container by pumping air therefrom and was controlled electronically. It could, however, comprise mechanical piston adapted to move in a cylinder in fluid communication with the sample container to control the air pressure therein. The suction means and the sample container must have been constructed such that the reduced pressure in the sample container above the sample may be maintained such that there is no unacceptable change in the level of the liquid in the sample container throughout the determination of the sedimentation rate. According to another form of the present invention there is provided a sampling apparatus for obtaining a sample volume of a liquid from a body of liquid and delivering the sample volume to an external vessel, the apparatus including: a gravity feed sample chamber adapted to be located below a liquid surface level of the body of liquid; a sample inlet from which liquid from the body of liquid can enter the gravity feed sample chamber; a sample outlet providing for fluid communication between the gravity feed sample chamber and external vessel; a gravity feed sample chamber pressure adjustment means operable to adjust pressure in the gravity feed sample chamber; wherein operation of the gravity feed sample chamber pressure adjustment means is used to apply a positive pressure to the gravity feed sample chamber to thereby cause the sample volume to be evacuated from the gravity feed sample chamber to the external vessel via the sample outlet; wherein the gravity feed sample chamber operates such that the liquid is not drawn by vacuum, thereby to facilitate operation in high temperature environments without boiling the liquid; and analytical means, by way of a sample apparatus, which provides a means of continually monitoring the effect of chemical dosing levels of the tailings feed. By analysing the tailings, the flocculent and coagulant pumps can be closely controlled. According to a another form of the present invention there is provided a method for obtaining a sample volume of a liquid from a body of liquid using a sampling apparatus, the sampling apparatus including a gravity feed sample chamber located below a liquid surface level of the body of liquid and in fluid communication with an external vessel, wherein the gravity feed sample chamber operates such that the liquid is not drawn by vacuum, thereby to facilitate operation in high temperature environments without boiling the liquid, the method including: charging the gravity feed sample chamber with at least the sample volume of the liquid by: opening the sampling apparatus to atmospheric pressure; and opening a sample inlet valve through which liquid from the body of liquid can enter the gravity feed sample chamber; evacuating the sample volume of the liquid from the gravity feed sample chamber to the external vessel by: closing the sample inlet valve; applying positive pressure to the gravity feed sample chamber to force the sample volume out of the gravity feed sample chamber and into the external vessel, wherein the rate of sedimentation is determined by analytical means, by way of a sample apparatus, which provides a means of continually monitoring the effect of chemical dosing levels of the tailings feed. By analysing the tailings, the flocculent and coagulant pumps can be closely controlled. Yet another form the present invention provides a sampling apparatus for obtaining a sample volume of a liquid from a body of liquid and delivering the sample volume to an external vessel, the apparatus including: a sample chamber adapted to be located below a liquid surface level of the body of liquid; a sample inlet from which liquid from the body of liquid can enter the sample chamber; a sample outlet providing for fluid communication between the sample chamber and external vessel; a sample chamber pressure adjustment means operable to adjust pressure in the sample chamber; wherein operation of the sample chamber pressure adjustment means is used to apply a positive pressure to the sample chamber to thereby cause the sample volume to be evacuated from the sample chamber to the external vessel via the sample outlet; wherein the rate of sedimentation is determined by analytical means, by way of a sample apparatus, which provides a means of continually monitoring the effect of chemical dosing levels of the tailings feed. By analysing the tailings, the flocculent and coagulant pumps can be closely controlled. The sample inlet may include an inlet valve selectively operable to open the sample chamber to allow fluid flow between the body of liquid and sample chamber and to close the sample chamber to prevent fluid flow between the body of liquid and sample chamber. The sample chamber pressure adjustment means may include a sample chamber atmosphere valve by means of which the sample chamber can be opened to atmospheric pressure and a sample chamber pressure valve through which compressed gas can be directed into the sample chamber. The external vessel may include an external vessel pressure adjustment means. The external vessel pressure adjustment means may include an external vessel atmosphere valve by which the external vessel can be opened to atmospheric pressure and an external vessel pressure valve through which compressed air can be directed into the external vessel. The sampling apparatus may further include a sample controller, the sample controller configured to charge the sample chamber with at least the sample volume by opening the sampling apparatus to atmospheric pressure and opening the sample inlet. Opening the sampling apparatus to atmospheric pressure may include opening the sample chamber atmosphere valve and opening the external vessel atmosphere valve. The sample controller may be configured to evacuate the sample volume from the sample chamber to the external vessel via the sample outlet by closing the sample chamber atmosphere valve, closing the sample inlet, opening the external vessel atmosphere valve, and applying compressed gas into the sample chamber via the sample chamber pressure valve. The sample chamber may include a first sub-chamber and a second sub chamber, the first and second sub-chambers being in fluid communication with each other. The sample chamber pressure adjustment means may be directly connected to the first sub-chamber and the sample outlet may be formed in the second sub-chamber. The sample chamber may be immersed in the body of liquid. The external vessel may include an external vessel outlet through which any liquid in the external vessel may be drained away. The external vessel may include a cleaning solution supply operable to flush a cleaning solution though the external vessel. In another form of the present invention provides a method for obtaining a sample volume of a liquid from a body of liquid using a sampling apparatus, the sampling apparatus including a sample chamber located below a liquid surface level of the body of liquid and in fluid communication with an external vessel, the method including: charging the sample chamber with at least the sample volume of the liquid by opening the sampling apparatus to atmospheric pressure; and opening a sample inlet valve through which liquid from the body of liquid can enter the sample chamber; evacuating the sample volume of the liquid from the sample chamber to the external vessel by closing the sample inlet valve; applying positive pressure to the sample chamber to force the sample volume out of the sample chamber and into the external vessel. The step of opening the sampling apparatus to atmospheric pressure may include opening the sample chamber to atmospheric pressure and opening the external vessel to atmospheric pressure. The step of evacuating the sample volume of the liquid from the sample chamber to the external vessel may include opening the external vessel to atmospheric pressure. The step of applying positive pressure to the sample chamber may include introducing compressed air into the sample chamber. The method may further include: evacuating the sample volume of the liquid from the external vessel; and clearing the sampling apparatus. The step of evacuating the sample volume of the liquid from the external vessel may include: opening the external vessel to atmosphere; and opening an external vessel outlet through which the sample volume drains from the external vessel. The step of clearing the sampling apparatus may include: closing the external vessel to atmosphere; opening the sample inlet valve; introducing compressed gas into the external vessel, the compressed gas flushing any residual liquid in the sampling apparatus out through the sample inlet valve.

Definitions For the purpose of the ensuing disclosure, the slurry feed entering the thickener is defined as "low solids" and the tailings exiting the thickener are defined as "high solids". The standard proprietary "Clarometer" apparatus draws the sample from the centre well and examines the settling characteristics of the slurry in-feed. From this measurement, the chemical dosing to the thickener is automatically controlled. The tailings feed exiting the thickener, having much higher solids content, requires a unique technique, which has given rise to the present invention.

Brief Description of the Drawings A preferred embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings in which: Figure 1 is a photograph of an example of the sample apparatus. The "Clarometer" provides a means of continually monitoring the effect of chemical dosing levels of the tailings feed to mechanical dewatering systems such as belt press filters and centrifuges. By analysing the tailings, the flocculant and coagulant pumps can be closely controlled. Figure 2 is a photograph of a process valve according to the present invention. A sample from the tailings line is fed into the Clarometer apparatus wherein the chemical reaction is examined. This step embodies the inventive technique, with the measurement referred to as "sample scatter". The process sample line is flushed after each operation. Figure 3 is a photograph of a control panel according to the present invention. The operator control panel is mounted adjacent to the Clarometer apparatus and includes a touch screen interface. In a preferred embodiment, three 4-20 mA signals; flocculant and coagulant pumps, plus "scatter", are produced for monitoring and control by the plant supervisory system. Figure 4 is a schematic diagram showing the association of the inventive process within a mechanical dewatering system. The three-way interaction of the sample apparatus, process valve and control panel is shown.

Detailed Description of a Preferred Embodiment The sampling apparatus and method of the present invention will be described in relation to the continual online analysis of the tailings feed from mechanical dewatering systems such as felt press filters and centrifuges. From this analysis, the chemical addition to the tailings is automatically controllable. Having regard to Figure 4 of the accompanying drawings, to obtain a sample, the process valve (1) is attached to the tailings feed line (2) via an appropriate conduit (3), in this case, a one inch British Standard Pipe (BSP). When the process valve (1) opens, a tailings sample (4) will flow through the conduit (5) to the control apparatus (6). There is also a water valve (7) which acts to flush the system on the completion of every sample. The process valve (1) and the water valve (7) are each actuated by air solenoids (8) and (9), respectively. The analysis is achieved through the control apparatus (6). It has two components: the main control apparatus (10) and the drainage tray (11). In an embodiment, they are mounted on a mobile trolley (not shown). On site, the drainage tray (11) may be bolted permanently to the floor through four mounting clamps (not shown). The tailings feed (4) enters the control apparatus (6) through the inlet (12). The conduit (5) from the process valve (1) is simply inserted into the inlet (12). The tailings feed (4) then passes through the apparatus (6) and into the drainage tray(11). At the base (13) of the drainage tray (11) there is a three inch BSB connection (not shown) for the return of the tailings (4) to the tailings feed line (2). In an embodiment, and as best shown in Figure 1, two support arms (14) attached to the drainage tray (11) provide a pivot point (15) to rotate the apparatus (6). In this embodiment, there are nine pivot points which enable easy adjustment of the flow angle. The apparatus (6) is then locked in position. The tailings (4) enter the inlet (12) and flow onto an item termed the scatter plate (not shown). As the tailings (4) spread on the scatter plate, they are analysed which results in a unique "scatter number" output, which is communicated via ethernet to the electrical control panel (16) This measured number is then compared to a reference value, the result of which automatically controls the chemical dosing pumps comprising the flocculant pump (17) and the coagulant pump (18). On completion of the process, the system is flushed with clean water via the water valve (7). It will be appreciated that the time interval between successive samples is adjustable. The control panel (16) contains the PLC (programmable logic controller) and operator touch screen (not shown). The control panel (16) is mounted adjacent the control apparatus (6) and communication between them is by means of an ethernet connection (19). The operator touch screen is a menu-driven system where all calibration variables are adjustable. There is an integral test facility where all components can be easily checked for correct operation. The inventive scatter technique involves a simple calibration procedure which is implemented through the touch screen. The analysis step, performed within the main control apparatus (10) is performed using a novel camera technique. A digital camera (not shown) is mounted adjacent a scatter plate (not shown) within the control apparatus (10), and is used to produce a monochrome image of the tailings as they spread out across the scatter plate. In certain forms, the monochrome image may be up to 350,000 pixels in resolution. The pixels are then counted according the sample and an algorithm is applied to give, in this exemplary instance, a practical number between 1 and around 275; this is colloquially termed the "scatter number". The scatter number is then correlated against known/measured standards, and the output determined against such standards. Simply, if the coagulation is beneath a predetermined standard value, more coagulant is injected into the system. Similarly, if the flocculation is beneath a predetermined standard value, more flocculant is added. Because the inventive system monitors high density tailings, whereas known systems monitor predominantly liquid slurries, this analytical technique is both novel and inventive. In summary, the inventive system provides continuous online monitoring of a high density tailings feed (4) to mechanical dewatering systems. It is safe, non intrusive (as the sample is returned to the process) and self-cleaning. Most importantly, it stands to optimise and reduce flocculant usage. It eliminates the labour and time requirement for operators to continually check tailings quality for the manual adjustment for the chemical dosing pumps. It will be understood that the invention disclosed and defined in this specification extends to all alternative combinations of two or more of the individual features mentioned or evident from the text or drawings. All of these different combinations constitute various alternative aspects of the invention. It will be further understood that the inventive system stands to optimise the amount of flocculant and/or coagulant added to high density tailings feed lines of mechanical dewatering systems. This has both economic and environmental implications and benefits. Although the invention has been described with reference to specific examples it will be appreciated by those skilled in the art that the invention may be embodied in many other forms.

Claims

THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:

1. A method when used for analysing a tailings feed having an elevated concentration of dispersed particles therein of a mechanical dewatering system, the method comprising the steps of: opening a process valve, thereby to permit fluid communication of the tailings feed to and across a scatter plate of a control apparatus; analysing the flocculation and coagulation characteristics of the tailings feed as it spreads across the scatter plate by obtaining a monochromatic image of the tailings feed, counting the pixels in the image and applying an algorithm to give rise to a scatter number; communicating the scatter number to a control panel associated with a flocculant pump and a coagulant pump; comparing the scatter number with user-defined reference values for flocculation and coagulation; and adjusting the dosage levels of the flocculation and coagulation pumps accordingly such that a defined amount of flocculant and/or coagulant is then provided to the mechanical dewatering system based upon the scatter number.

2. A method according to claim 1, wherein the tailings feed is returned to the mechanical dewatering system following analysis, by way of a drainage tray in fluid communication with the mechanical dewatering system.

3. A method according to claim 1 or claim 2, wherein the analysis is substantially continuous, or takes place at predetermined intervals.

4. A method according to any one of the preceding claims, further comprising a washing step, wherein the control apparatus and associated conduits are periodically flushed with water.

5. A method according to any one of the preceding claims, wherein the washing step is associated with a water valve and an air solenoid in fluid communication with a water source.

6. An apparatus when used for analysing a tailings feed having an elevated concentration of dispersed particles therein of a mechanical dewatering system, the apparatus comprising: means for opening a process valve, thereby to permit fluid communication of the tailings feed to and across a scatter plate of a control apparatus; means for analysing the flocculation and coagulation characteristics of the tailings feed as it spreads across the scatter plate by obtaining a monochromatic image of the tailings feed, counting the pixels in the image and applying an algorithm to give rise to a scatter number; means for communicating the scatter number to a control panel associated with a flocculant pump and a coagulant pump; means for comparing the scatter number with user-defined reference values for flocculation and coagulation; and means for adjusting the dosage levels of the flocculation and coagulation pumps accordingly such that a defined amount of flocculant and/or coagulant is then provided to the mechanical dewatering system based upon the scatter number.

7. An apparatus according to claim 6, further comprising means, in the form of a drainage tray in fluid communication with the mechanical dewatering system for returning the tailings feed to the mechanical dewatering system following analysis.

8. An apparatus according to claim 6 or claim 7, wherein the analysis is substantially continuous, or takes place at predetermined intervals.

9. An apparatus according to any one of claims 6 to 8, further comprising means for effecting a washing step, wherein the control apparatus and associated conduits are periodically flushed with water.

10. An apparatus according to any one of claims 6 to 9, wherein the means for effecting the washing step is associated with a water valve and an air solenoid in fluid communication with a water source.

Dated this 24th day of June 2021 Shelston IP Attorneys for: Oscillation Pty Ltd