Priority Cross-Reference

[0001] The present application claims priority from Australian Provisional Patent Application No. 2022902446 filed 26 August 2022 the contents of which is to be considered to be incorporated into this specification by this reference.

Technical Field

[0002] The present invention relates to a sensor apparatus for sensing or measuring physical and/or chemical parameters of a saturated environment, such as a body of liquid, including liquid suspensions, dilute suspensions, or slurries. The present invention has been developed primarily for use in the mining industry in leaching applications, in relation to the analysis of leach solution collected from in situ leaching, column leaching and heap leaching operations and it will be convenient to describe the invention in relation to leaching applications.

[0003] However, it is to be appreciated that the present invention could have wider application such as in the areas of natural water monitoring, processed water monitoring, fish pond water monitoring, acid mine drainage, environmental remediation including soil remediation, oil recovery, geologic carbon sequestration, migration and remediation of nonaqueous phase liquids in sub-ground surface environments, and in infiltration/flooding phenomena in extreme weather events to name examples only. Accordingly, the invention is not to be understood as being restricted to mining applications or leaching applications only.

Background of the Invention

[0004] The following discussion of the background to the invention is intended to facilitate an understanding of the invention. However, it should be appreciated that the discussion is not an acknowledgement or admission that any aspect of the discussion was part of the common general knowledge as at the priority date of the application.

[0005] In certain sectors of the mining industry, minerals are extracted from ores by a process known as “heap leaching”, which involves laying very large bodies of mined or crushed ore into a heap on an impervious sheet liner (rubber liner for example) and irrigating the heap from above with a solvent liquid (typically sulfuric acid) to liberate/dissolve minerals and/or metals from the ore. The solvent passes through or percolates the ore from top to bottom, liberating/dissolving minerals and/or metals from the ore as it flows, and forming a ‘pregnant’ leach solution (PLS). The PLS flows along the sheet liner to a collection point or area where it is removed for subsequent processing in a treatment facility to isolate the target minerals/metals.

[0006] The optimum mineral/metal extraction rate in a heap leaching process will be dependent on such parameters as temperature, pH, redox potential (Eh, or oxidation-reduction potential (ORP)), solution chemistry, oxygen level and conductivity, amongst others. Heap leaching operators monitor the input lixiviant and the PLS continuously during to the leaching process, which is carried out over months or years. Over this time, the monitored parameters will continuously change as the chemical reactions taking place in the heap change during the leaching process. For example, the dissolution of copper ore from the heap can consume the sulfuric acid, the ferric and oxygen, but will produce a side product that includes acid, sulphur and jarosite.

[0007] In order to meet or approach an optimum mineral/metal extraction rate in a particular heap leaching process, the leaching process can be modelled or simulated in column leaching facilities in a laboratory. These facilities are testing apparatus consisting of one or more vertical columns containing a sample of the ore from the ore heap in which a solvent liquid is introduced onto the top of the ore within the column and which flows through the ore for collection at the base of the column. The liquid is collected for subsequent analyses to measure or determine the interaction between the ore and the solvent, and this can assist to understand or predict interactions between the ore and the solvent in the actual heap and enables taking action (remedial or otherwise) based on the analysis.

[0008] While column leaching in a laboratory setting can provide useful information for a heap leaching process, column leaching facilities available to date do not always provide a sufficiently useful simulation of leaching within a heap. One problem with existing column leaching facilities is that there is a lag between sampling the liquid that is collected at the base of the column, analysing the sample and taking action (remedial or otherwise) based on the analysis. This lag time does not support prompt responsiveness to environmental or process issues relating to leaching occurring in the actual heap.

[0009] It is therefore an aim of the present invention to provide an improved or alternative sensor apparatus for use with column leaching facilities and within a heap itself, which reduces the time lag between sampling and analysing a leach solution. More broadly, the present invention aims to provide an improved or alternative sensor apparatus compared to relevant existing arrangements, or which provides an alternative choice for operators of liquid testing systems, such as column leaching facilities.

Summary of the Invention

[0010] According to the present invention there is provided a sensor apparatus having: a sensor mount for mounting one or more sensors in a body of liquid, the sensor mount having a mounting portion to which one or more sensors are mounted, so that a sensing portion of the one or more sensors projects from the mounting portion for immersion in the body of liquid, a filter assembly extending about the sensing portion of the one or more sensors to filter flow of particulate within the body of liquid into contact with the sensing portion of the one or more sensors.

[0011] The sensor apparatus is intended for use with a body of liquid and clearly, such a body can be the liquid output from a heap, or from a column leaching facility, such as from an individual column of a column leaching facility. However, the sensor apparatus of the present invention can be used with many different liquids including those that contain low levels of particulate, such as dilute suspensions or slurries. The body of liquid can alternatively be any other suitable liquid that is collected in a container and that requires analysis. The body of liquid could for example, be a naturally occurring body, such as a dam (a tailings dam at a mine site for example), a river, a pond, the sea (for example a sea-based fish farm). Accordingly, the sensor apparatus according to the invention can be employed in any suitable liquid environment. [0012] Moreover, the sensor apparatus of the present invention can operate to measure physical and/or chemical parameters of a liquid in situ and continuously.

[0013] When the sensor apparatus of the present invention is employed with the liquid output from a heap, or from a column leaching facility, the output, such as from an individual column of a column leaching facility, can discharge into a container, which can be as simple as a bucket, or alternatively can be a more complex container. Regardless, a body of liquid is provided in the container and the sensor apparatus can be placed relative to the liquid to immerse the sensing portions of the one or more sensors in the liquid to commence the sensing, analysis, or measurement process.

[0014] The sensor mount is provided to mount the one or more sensors of the sensor apparatus in a body of liquid. This can involve the sensor mount connecting with a container in which the body of liquid is contained or connecting to a structure, such as framework of a facility positioned relative to the body of liquid. This can involve direct connection of the sensor mount with the container or the structure of a suitable facility, or indirect connection such as by suspension of the sensor mount relative to a body of liquid by struts, flexible connectors (cables, chain, etc) or feet for example. It is not necessary that the entire sensor be immersed in the body of liquid, although that might be appropriate, but usually, it is a portion of the sensor that is immersed.

[0015] Alternatively, the sensor mount can be provided to mount the sensors of the sensor apparatus and an alternate part of the sensor apparatus can be arranged for interaction with or connection to the container or the structure of a suitable facility, to locate the sensor apparatus and thus the sensor mount and the sensors of the sensor apparatus in position relative to a body of liquid. In some embodiments of the present invention, the sensor mount is connected to the filter assembly and the filter assembly is configured for seating on the base of a container and with the filter assembly seated on the base of a container, the sensor mount is located in position such that the sensors of the sensor apparatus become immersed in a body of liquid contained in the container. By seating the sensor apparatus on the base of a container and without otherwise confining the sensor apparatus, the sensor apparatus can be manipulated easily, such as to move the sensor apparatus into and out of a container that contains, or is going to contain, a body of liquid.

[0016] The sensor mount may include a base that allows the sensor mount to stand up in a container in which a body of liquid has been collected. The base may be configured to sit on the base of the container and may for example, have a flat bottom surface.

[0017] Alternatively, the base may be configured to positively cooperate with the base of a container. The base of the sensor mount may, for example include an opening to receive a boss or spigot that extends upwardly from the base of the container.

[0018] Alternatively, the sensor mount can be configured for fixing to the base of the container, such as by screws. For this, the base of the sensor mount can include a flange through which screws can extend.

[0019] Alternatively, the sensor mount can be top-mounted or side-mounted to a container, or two or more of base, top and side mounting may be provided to increase the options for mounting or to increase the stability by which the sensor mount mounts within a container. A top mount may include a flange for securing an upper portion of the sensor mount to a container lid or to part of the frame of the column leaching facility for example.

[0020] Still further alternatives for mounting the sensor apparatus relative to a body of liquid include connecting one or more of the sensors to the container or the structure of a suitable facility, so that the sensor mount itself is not directly connected to the container or the structure of a suitable facility, but rather, the sensors, or more likely cables associated with the sensors, secure the sensor apparatus in position. In this arrangement, the sensing portions of the one or more sensors will project from one side or in one direction from the sensor mount for immersion in the body of liquid and trailing portions of the one or more sensors will usually project or extend from the sensor mount in a different and usually opposite direction for connection to data collection, transmission or processing equipment, such as by cable connection. In these forms of the invention, the trailing portions of one or more of the sensors can be secured or connected in a manner that the sensor mount is suspended relative to the body of liquid and the sensing portions of the one or more sensors are immersed in the body of liquid.

[0021] In alternative arrangements, the sensor apparatus can have a buoyancy such that it can float upright in a body of liquid. Any part of the sensor apparatus can provide that buoyancy and for example, in some forms of the invention, the sensor mount has a hollow portion that defines an interior within which the mounting portions of the one or more sensors are enclosed. In some forms of the invention, the sensor mount can be formed as a tube or cylinder. In these forms of the invention, the hollow portion can provide buoyancy, or the hollow portion can be partly or fully filled with a buoyant material such as an expandible foam. This is discussed in more detail later herein. In these arrangements, additional connection of the sensor apparatus to the container or other structure may not be necessary.

[0022] It is to be noted that at least for the example where the sensor apparatus is intended for use in a body of liquid which is the liquid output from a column leaching facility, the body of liquid collected within a container from the outlet of a column will in general not be particularly turbulent and so highly secure mounting of the sensor mount within the container is not necessarily required. In prototype testing to date, the sensor apparatus is suitably secured within a container of PLS by the apparatus having a base that sits or rests on the base of the container and by the trailing portions of the sensors being in connection with suitable data collection, transmission or processing equipment, such as by cable connection. Advantageously, this means that the sensor apparatus can be connected to the relevant data collection, transmission or processing prior to being inserted into the container and flexible cables connecting the sensor apparatus to that equipment allows easy insertion of the sensor apparatus into the container.

[0023] It is to be understood that while the body of liquid may not be particularly turbulent in most uses of the sensor apparatus according to the invention, the body of liquid will be a flowing body, or a replenishing body, in that liquid will continuously be flowing into and out of the container and thus flowing through the sensor apparatus and so the sensor apparatus will be subject to liquid flow loads. Typically therefore, some form of retention of the sensor apparatus will be required, although in some uses of the sensor apparatus, it will be allowed to move freely within the body of liquid based on where the current within the body of liquid takes it.

[0024] The sensor mount may itself be immersible within the body of liquid, so that in use, each of the sensor mount and the sensing portions of the one or more sensors are immersed within the body of liquid. Alternatively, the sensor mount may be arranged to sit above the body of liquid but to position the sensing portions of the one or more sensors for immersion within the body of liquid. In prototype forms of the present invention, there has been at least partial immersion of the sensor mount in the body of liquid when the sensing portions of the one or more sensors are immersed in a body of liquid.

[0025] In a simple form of the invention, the sensor mount may be a disc, a plate, a block, a wire, a mesh or a spiral to which the one or more sensors are mounted, or through which the one or more sensors extend. The portion of the one or more of the sensors that interacts with the sensor mount can be a mounting portion. The sensor mount may include openings for extension of the one or more sensors through the sensor mount. These openings may be provided in the mounting portion of the sensor mount. The sensor mount may be formed by a settable liquid, such as a resin or foam, being set about the mounting portions of the one or more sensors.

Alternatively, the sensor mount may include clips or catches for attachment of the one or more sensors to the sensor mount, or it may allow fastening of the one or more sensors to the sensor mount, such as by screw connector.

[0026] The sensor mount can be made from any material that is suitable for exposure to the body of liquid that the sensing portions are to be immersed in, either through the sensor mount being partially or fully immersed in the body of liquid, or by it being exposed to splashing from the liquid or to vapours emitted by the liquid.

[0027] In one form of the invention, the sensor mount has a body portion provided to enclose or accommodate mounting portions of the one or more sensors. The mounting portions can be mounted within the body portion against contact with liquid in the body of liquid while the sensing portions of the one or more sensors are positioned outside the body portion for immersion in a body of liquid. [0028] As indicated above, in some forms of the invention, the body portion of the sensor mount has a hollow portion that defines an interior within which the mounting portions of the one or more sensors are enclosed. In some forms of the invention, the body portion can be formed as a tube or cylinder. The hollow portion can be closed at least in the region where the one or more sensors project out of the body portion for immersion of the sensing portions of the one or more sensors in the body of liquid. The hollow portion can be closed by a base that forms a closure and the mounting portion of the sensor mount, and where the body portion is a tube or cylinder, the base can extend across the tube or cylinder and can be located at a bottom end of the tube or cylinder. The base or closure prevents liquid in the body of liquid entering the interior of the hollow portion and this protects the mounting portions of the one or more sensors from contact with the liquid. The base or closure can include openings through which the one or more sensors can extend.

[0029] While protection of the mounting portions from contact with the body of liquid can be beneficial against damage, particularly where the body of liquid is aggressive and corrosive, a different benefit of the body portion is that it neatly captures the one or more sensors in a confined space. Accordingly, the body portion can form a sensor containment area having a base and a generally square, rectangular, or cylindrical wall, or any other shape of continuous wall, which is upstanding from the base and within which the hollow portion is formed.

[0030] Where the body portion of the sensor mount has a hollow portion that defines an interior within which the mounting portions of the one or more sensors are enclosed, the interior can be open, for accommodating the mounting portions of the one or more sensors. In this form of the invention, the mounting portions of the sensors can extend through a base of the body portion and can be secured by extension through the base. Alternatively, the interior can be filled, such as with a liquid settable filler that extends or flows about the mounting portions of the one or more sensors within the interior so that the hollow portion is no longer hollow, but rather, is solid. Advantageously, the filler can form the mounting portion of the sensor mount and securely locates the one or more sensors within the sensor mount, in particular against movement relative to each other, while the filler can also protect the one or more sensors from contact with the body of liquid. In some forms of the invention, the filler can be buoyant for providing buoyancy to the sensor apparatus. [0031] The hollow portion can be closed by a closure such as base as discussed above, and in those arrangements, the filler fills the hollow portion from the base upwards. Alternatively, the hollow portion can be open at each end (an open ended tube for example) and the filler can form a closure at each end once it sets. In this form of the invention, the filler is exposed to the body of liquid when the sensing portions of the one or more sensors are immersed in a body of liquid and so the filler is chosen to have characteristics suitable not to degrade or fail when exposed to the body of liquid.

[0032] In the above form of the invention, the sensors can first be installed within the hollow portion of the body portion and then a suitable settable filler can be fed into the hollow portion to fill the hollow portion about the mounting portions of the one or more sensors. Where the body portion includes a base, the mounting portions of the one or more sensors can be fed through openings in the base and if appropriate, can also be fixed to the base prior to the filler being introduced. This locates the one or more sensors prior to the filler being introduced. The filler can fill the hollow portion so that there are no gaps within the hollow portion. Moreover, because the filler can fill the hollow portion, there may be no need for the sensor containment area to be closed by a base. Rather, the sensor containment area can comprise a wall and the hollow portion can be closed where the one or more sensors project out of the body portion by a base surface or terminal end formed by the set filler.

[0033] The settable filler can be any suitable filler, such as one that will not degrade or fail if exposed to the body of liquid. Different fillers may therefore be appropriate for different liquid environments. The leach solution that would be collected from a heap or a column leaching facility will typically be a particularly aggressive liquid, being strongly acidic and highly oxidative. In addition, the sensor apparatus can be exposed to high temperatures. In this environment, suitable fillers include epoxy resins, E30, E60, and general silicone sealants/silastics of different types. Liquified polymers such as PLA, PVC, polycarbonate can also be employed using thermal arrangements to flow the fillers into position.

[0034] In other environments, less robust fillers might be suitable and for example, include expandible foams, which can be buoyant foams. Advantageously, these foams can be used to create a lower density portion of the body portion and the sensor apparatus to create a self-orientating buoyancy effect to retain the sensor apparatus upright within a body of liquid.

[0035] As discussed above the sensors can be inserted into the hollow portion of the body portion before a suitable settable filler is fed into the hollow portion to fill the hollow portion about the mounting portions of the one or more sensors. Alternatively, the hollow portion can be filled first and the one or more sensors, or their connecting cables, then pushed through the filler prior to it setting. This latter arrangement allows the hollow portion to be properly filled before the sensors are introduced into the hollow portion.

[0036] The hollow portion of the body portion can be filled completely from one end to the other with the settable filler, or it can be partially filled. All that is required is that the sensors mounted in the hollow portion are securely mounted. Accordingly, a portion of the hollow portion can remain hollow after the settable filler has been introduced. This can allow, for example, the sensors to be connected to transmission cables within the remaining hollow portion, providing protection to the connections. This can also allow for wireless transmission components of the one or more sensors to be housed within the remaining hollow portion, again, for providing protection to those components. Alternatively, the sensors can extend out of the hollow portion for connection to transmission cables or the wireless transmission components can be positioned out of the hollow portion.

[0037] The one or more sensors described above have mounting and sensing portions. These may just be different sections along the length of a sensor. For example, a sensor may include a transmission connection or a wireless transmission component for transmitting sensed data at one end and a relevant sensing component at the opposite end and a cable extending therebetween. The mounting portion could then be one part of the cable and the sensing portion could include another part of the cable and the sensing component. The expressions “mounting portions” and “sensing portions” do not necessarily require distinctly different component parts.

[0038] In some forms of the invention, the one or more sensors have a connection portion that extends from the sensor mount for connection to transmission wires or cables or other suitable connectors for transmitting sensed data to data collection, transmission or processing equipment, such as a computer. In other forms of the invention, the one or more sensors have wireless transmission components for the same purpose. Thus, the one or more sensors can alternatively connect wirelessly to data collection, transmission or processing equipment, such as a computer, for transmitting sensed data to the data collection, transmission or processing equipment wirelessly. Wireless sensors do not need to have the connection portion discussed above, but rather, the portion of the sensors that extends from the sensor mount can have a wireless transmission facility. A sensor apparatus according to the invention can have a mixture of these types of sensors. For simplicity, reference hereinafter to “connection portions” is to be understood as encompassing any form of connection of a sensor to data collection, transmission or processing equipment, and includes wireless transmission components for wireless connection to such equipment.

[0039] The connection portions of the one or more sensors can extend in an opposite direction to the sensing portions of the one or more sensors and in some forms of the invention, the one or more sensors can extend generally straight through or linearly through or past the sensor mount, or the mounting portion of the sensor mount, so that the sensing and connection portions extend from opposite ends or sides of the sensor mount , or the mounting portion of the sensor mount, and in opposite directions. It is expected that the connection portions of the one or more sensors will be sufficiently distanced from the body of liquid by the intervening body portion that protection of the sensors beyond normal protective casings will not be required.

[0040] The connection portions of the one or more sensors may only need to project from the body portion a short amount for connection to relevant transmission wires or cables or other suitable devices, or, as discussed above, the connection portions can remain within the body portion for connection within the body portion.

[0041] In some forms of the invention, the one or more sensors are mounted by the sensor mount generally vertically in a body of liquid, so that the sensing portions of the one or more sensors extend downwardly from the sensor mount generally vertically for immersion in a body of liquid and the connection portions of the one or more sensors extend upwardly from the sensor mount generally vertically, such as for connection to transmission wires or cables or other suitable devices.

[0042] In some forms of the invention, the sensor mount, the mounting portion of the sensor mount, or the body portion of the sensor mount, connects to a support that terminates in a base and the base is of the form that can sit or rest on or connect to the base of a container that contains the body of liquid within which the sensing portions of the one or more sensors are to be immersed, or the base can connect to the filter assembly, thus connecting the sensor mount to the filter assembly. The support can be a stem or other member and the base can be enlarged relative to the dimensions of the support to support the sensor mount in an upright position within a container. The sensing portions of the one or more sensors can extend from the sensor mount adjacent to the support and on either side of the support. The support could comprise a pair of support members, such as that extend from opposite sides of the sensor mount. The support can be used to support or locate one or more of the sensing portions of the one or more sensors.

[0043] The filter assembly that extends about the sensing portions of the one or more sensors is provided to restrict flow of particulate within the body of liquid into contact with the sensing portions of the one or more sensors in order to minimise or eliminate the formation of precipitants or depositions that would otherwise foul the sensors. The filter assembly has a protective function to protect the sensing portions of the one or more sensors against build-up of particulate on the sensing portions so that the sensors can function properly for an acceptable period of time.

[0044] The filter assembly can take any suitable form, but must allow access of the liquid in the body of liquid to the sensing portions of the one or more sensors, so that the sensors can perform the sensing function in relation to the body of liquid. The filter assembly operates to minimise the formation of precipitation and biofouling on the sensing portions of the one or more sensors. As indicated above, the liquid in the body of liquid will typically be flowing or dynamic rather than static and so the filter assembly needs to allow flow of liquid through it, but at the same time filtering particulates that might otherwise deposit on the sensors from reaching the sensors. [0045] In some forms of the invention, the filter assembly includes a filter that extends about the group of sensing portions of the one or more sensors and which is intended to extend about the sensing portions in all directions or routes that liquid in the body of liquid can take to access the sensing portions. In this form of filter assembly, the filter assembly extends about the entire group of sensing portions and differs from arrangements in which individual filters extend about individual sensing portions.

[0046] The filter can be a filter material. This can be a mesh or sponge material, or a foam material and the filter can be of a single material or of a composite material. For example, the filter material can include one or more of (i) mesh to filter coarse particles, (ii) sponge, such as inside of the mesh to filter or retain finer particles, and (iii) filter film and fibres, such as immediately inside of the sponge and adjacent the sensing portions of the one or more sensors to filter or retain ultra-fine particles. Example materials for use as filter materials include filter paper, polymer membrane or foams and fabric. Specific materials include nylon, polypropylene, polyester, viscose cellulose esters, PMMA, Teflon, HDPE, glass fibre, and graphitic polymer mixed filter materials. The filter materials can be mixtures of one or more of these materials. The filter can be a sponge and can include the combination of hydrophobic fibres and hydrophilic fibres, while graphitic material could also be used.

[0047] The mesh of the filter material that filters coarse particles can be provided to filter particulates sized larger than approximately 6 mm in width or diameter. The sponge of the filter material that filters or retains finer particles can be provided to filter or retain particulates sized in the range of 10 micrometre to 2 mm. The filter film and fibres that filters or retains ultra-fine particles sized in the range of <1 micrometre to 100 micrometres.

[0048] The selected filter, such as a sponge filter, can have particular chemical or physical properties, or can be modified to have such properties, which allows the filter material to not only act as a particulate filter but to provide inherent chemical or physical properties which enhance selective capture or adsorption of particular particulates by the filter material, ie a “smart sponge”. Examples of sponge materials that have appropriate properties include a positively charged sponge material, which can provide enhanced electrostatic adsorption of negatively charged particulates (or vice versa), or a hydrophobic filter material (sponge) may be beneficial in the attraction of hydrophobic particulates (or vice versa). A filter material coated with specific chemical functional groups may be beneficial in the chemisorption or chelating of particular particulates with particular surface chemistry or a filter material coated or loaded with a specific surfactant or flocculant or filter aid which aids or promotes the aggregation of ultrafine particles, which would otherwise pass thru the filter material, into larger agglomerates which will be captured. Still further, a filter material having a particular morphology such as sponge particle shape, porosity, or surface area that promotes entrapment or capture or attraction of particular particulates of specific shape or size or molecular structure could also be beneficial.

[0049] The filter type and pore size can be selected based on the expected size of the particulate in the body of liquid, such as the minimum expected size, so that a majority of the particulate is caught by the filter before the liquid gains access to the sensing portions. In this respect, the liquid collected from a heap, or a column leaching facility and other bodies of liquid that the sensor apparatus of the present invention is intended to be used with, will typically be in continuous flow so that the liquid will be constantly entering or exiting the sensing area or location, rather than the liquid being a stagnant body of liquid, and so the liquid will be constantly flowing through the filter assembly. The sensor apparatus advantageously provides real time sensing to sense the changing properties of the body of liquid over time, but the filter assembly will be constantly filtering and so the filter assembly will need to be cleaned or changed periodically depending on the level of particulate captured by the filter assembly and the degree to which this clogs the filter.

[0050] In some forms of the invention, filter material can be secured by or within a frame or cage. An example frame can include one or more layers of perforated wall that extend about the sensing portions of the one or more sensors and the filter material can be secured to the perforated wall either on the inside of the wall or the outside. The perforated wall can form a skirt about the sensing portions of the one or more sensors and the skirt can be circular or cylindrical for example. The wall is perforated to allow travel of liquid through it. The perforations can be of a size that has a filtering effect that is in addition to the filtering effect of any filter material, or the perforations can be sized so that they have no filtering effect. For example, in some environments, there may be need to filter large particles as well as fine particles and the filter assembly might be arranged with a filter material inside of the perforated wall, so that large particles are filtered by the perforated wall (or the perforated wall forms a barrier to the passage of large particles past the perforated wall) and fine particles pass through the perforated wall and are filtered by the filter material. The perforated wall may filter coarse particles of the size range discussed above, or the perforated wall may filter larger particles, so that the coarse particles of the size range discussed above pass through the perforated wall and are filtered or retained by the filter material.

[0051] The perforated wall can be formed as a generally square, rectangular, circular or cylindrical wall, or any other shape of continuous wall. The perforated wall can be upstanding from a base. The base can be solid or perforated. The base can be configured to sit on the base of a container in which a body of liquid is to be collected and so may for example, have a flat bottom surface. Liquid within the body of liquid is therefore prevented from flowing into the interior of the frame or cage through the base and can only flow through the perforated wall. Therefore, with the filter material on the inside of the perforated wall, the liquid must flow through the perforated wall and then through the filter material before it reaches the sensing portions of the one or more sensors for sensing. The liquid is thus filtered prior to reaching the sensing portions and so the sensing portions are protected from particulate material that would otherwise reach and possibly collect or deposit on and foul the sensing portions.

[0052] In some forms of the invention, filter material is located or sandwiched between inner and outer perforated walls. These can be walls having the same general shape but with the inner wall fitting inside the outer wall with a gap between them to accommodate the filter material. The inner and outer perforated walls can both be cylindrical for example.

[0053] The perforated wall can be formed with openings which have edges of that are shaped to shed particulate material to prevent or minimise the collection and build-up of particulate material on the walls. By shedding particulate material, the material will not block the openings in the perforated wall and will more likely precipitate downwards to collect on the bottom of the container containing the body of liquid for later disposal. The openings can be arranged particularly to shed coarse and medium sized particulate material away from any filter material that may be located adjacent to a perforated wall, or that is sandwiched between inner and outer perforated walls. In some forms of the invention, the edges of the openings are inclined so that any particulate that lands on the edges tends to shift off the edges by the action of gravity and agitation caused by the flow of liquid through or about the perforated wall. The direction of inclination depends on the construction of the filter assembly, but where the filter assembly includes an outer perforated wall and an inner filter material, the openings could be inclined away from the filter material. Where the filter assembly includes spaced apart outer and inner perforated walls and a filter material between them, the openings of the respective outer and inner perforated walls could be inclined in different directions and both away from the filter material. Openings that shed particulate material can have different shapes, but in some forms of the invention, the openings have a diamond shape.

[0054] The frame or cage might have no filtering effect at all in some environments where the particulate material is very fine so that filtering is conducted by filter material alone. In these environments, the frame will form a support or mount for the filter material and the wall perforations will be provided only for the purpose of allowing liquid flow through the frame to the filter material and on to the sensing portions of the one or more sensors.

[0055] The filter assembly can connect to the sensor mount to secure the filter assembly to the sensor mount. The connection can be a releasable connection. For example, the connection can be a quick release connection to make the filter assembly easily and quickly replaceable or removable for cleaning in case filter material of the filter assembly accumulates excessive filtered particulate materials. Alternatively, the filter assembly can be permanently fixed to the sensor mount, but with a removable filter material which can be removed for cleaning or replacement.

[0056] The sensor apparatus according to the present invention can also include a vibration device to impart vibration to the sensing portions of the one or more sensors, to displace particulate material that deposits, precipitates, crystallizes, lodges or grows on the sensing portions. The vibration device can be housed within or on the sensor mount with the mounting portions of the one or more sensors, and vibration of the vibration device will impart vibration to the sensor mount that will translate to the mounting portions of the one or more sensors connected to the sensor mount (such as connected to the mounting portion of the sensor mount) and that will translate to the sensing portions on which particulate material may have deposited, lodged or grown. Alternatively, the vibration device can be located adjacent the sensing portions of the one or more sensors to impart vibration directly to the sensing portions.

[0057] The vibration device can operate continuously, or intermittently. Where it operates intermittently, the frequency of operation can be selected based on the amount and the rate of the formation of precipitation on the sensing portions, either known (measured for example) or estimated. For example, in a heap or a column leaching facility, higher frequency operation will likely be required in higher temperature and/or high pH leaching environments (typically high precipitation environments), and this might require operation once or multiple times per hour over a period of months. The frequency at which the vibration device vibrates can be in the range of 30 to 60 Hz. The vibration device can have a power requirement of about 3 Watts.

[0058] It is anticipated that despite the provision of a filter assembly, particulate material will still pass through the filter assembly and into proximity to the sensing portions of the one or more sensors. That particulate material could be ultra-fine material for example. That particulate material can be dislodged from deposit or collection on the sensing portions by vibration of the vibration device and can be collected or accumulated within the filter assembly for later removal. In some forms of the invention described above, the frame or cage includes a base and an upstanding perforated wall, and particulate material can accumulate on the base within the perforated wall. Perforations in the perforated wall can commence above the base, so that there is a solid portion of the perforated wall in connection with the base that forms a surrounding wall and the base and the solid portion of the perforated wall form a containment area for collecting the particulate material.

[0059] The sensor apparatus according to the present invention can also include an arrangement to generate liquid flow about the sensor portions of the one or more sensors. This can be useful where the sensor apparatus is employed in stagnant bodies of liquid or in bodies of liquid with low or insufficient liquid flow, or irregular liquid flow about the sensing portions. The use of liquid flow generation allows a sensor apparatus, according to the present invention, to ensure liquid flow about the sensor portions at required or preferred flow rates. The generated flow may also be through the filter assembly so that the generated flow causes ingress and egress of liquid to and from the filter assembly. The sensor apparatus may include porting or openings for liquid flow and can for example, include an inlet port or opening and an outlet port or opening through the filter assembly. These may be the same port or opening or may be separate ports or openings. Either of an inlet or outlet port or opening may have a suction device, such as a suction pump, associated with it to suck liquid into or out of the area about the sensor portions. Suction associated with the inlet or outlet ports or openings may be part of a suction or pumping system associated with the body of liquid with which the sensor apparatus is employed, such that the body of liquid may be subject to pumping to generate or supplement liquid flow or movement and that pumping may also generate liquid flow or movement in the area about the sensor portions.

[0060] A sensor apparatus according to the present invention can sense and process data close to the sensing source (the body of liquid) so that the analysis of the data commences as the data is collected or established and so the data is up to date and immediate. The sensor apparatus can be built to be readily portable and the components of the sensor apparatus can be readily removable for cleaning or replacement. Importantly, prototypes created to date are also robust and capable of operation in aggressive chemical environments.

Brief Description of the Drawings

[0061] In order that the invention may be more fully understood, some embodiments will now be described with reference to the figures in which:

[0062] Figure 1 is a front view of a sensor apparatus according to one embodiment of the present invention.

[0063] Figure 2 is a front view of the sensor apparatus of Figure 1 , partially dismantled. [0064] Figure 3 is a bottom end view of the sensor apparatus of Figure 1 , while

Figure 7a is a view of the Figure 3 arrangement from the opposite end,

[0065] Figure 4 is a perspective view of a sensor mount of the sensor apparatus of Figure 1

[0066] Figures 5 to 9 are front perspective, side, rear perspective, front and top views of the sensor mount of Figure 4.

[0067] Figure 10 is a view of the sensors mounted in the sensor apparatus of Figure 1 .

Detailed Description

[0068] Figure 1 is a perspective view of a sensor apparatus 10 according to one embodiment of the present invention. The sensor apparatus 10 includes a sensor mount 12 and a filter assembly 14, while upper ends of a plurality of sensors 16 project out of an upper end of the sensor mount 12.

[0069] The filter assembly 14 forms a frame or cage about bottom or sensing portions or ends of the sensors 16 (which are obscured from view in Figure 1 ) and comprises an outer cylindrical skirt or tube 18 and an inner cylindrical skirt or tube 20. The tube 20 is visible in Figure 2 which shows the sensor apparatus 10 with the outer tube 18 removed. The respective tubes 18 and 20 are coaxial and the inner diameter of the tube 18 is greater than the outer diameter of the tube 20 (as shown in Figure 3) to create a cylindrical gap G between the respective tubes 18 and 20. The gap G is provided for receipt of a filter material (not shown) of any of the kinds described earlier herein.

[0070] The filter assembly 14 can protect the bottom or sensing portions of the sensors 16 that are mounted in the sensor mount 12. The bottom or sensing portions of the sensors 16 are sensing devices 17 as shown in Figures 4 and 10. Figure 4 shows the sensor mount 12 in isolation with the sensors 16 shown mounted within the body portion 22 of the sensor mount 12. Figure 4 shows that the body portion 22 is formed as a cylinder so that the interior of the body portion 22 is hollow. As shown in Figure 4, the sensors 16 extend from above the body portion 22 and through the interior of the body portion 22 to exit through the bottom end 24 of the body portion 22. The hollow interior of the body portion 22 thus forms a sensor containment area within which a mounting portion of the sensors 16 (a middle portion as shown in Figure 4), is contained. It will be described later herein that the hollow interior of the body portion 22 is partially filled with a settable fill material to locate and fix the sensors 16 within the body portion 22 and to seal the bottom end of the interior of the body portion 22 against ingress of liquid when the sensor assembly 10 is immersed in a body of liquid. In this illustrated embodiment, the settable fill material forms a mounting portion of the sensor mount 12.

[0071] The sensor mount 12 includes a base 26 which connects to the body portion 22 by a support 28 which is a generally rectangular stem. This construction is shown in the other Figures 5 to 8 which show the sensor mount 12 in isolation and in different orientations. The base 26 has a flat bottom surface 30 which can connect to or rest on the inside of the base 44 of the tube 20. The base 44 allows the sensor apparatus 10 to sit or rest on the base of a container that is used to collect the body of liquid to be analysed, although the sensor apparatus 10 can alternatively be suspended within a container and thus not engage the base of the container. The base 26 is shaped as a truncated irregular cone and the angle of the cone is selected to assist to shed contaminant/particles that dislodge from the sensor surfaces and accumulate on the cone surface. The cone shape also assists to slow down the flow of the liquid through the sensor apparatus 10.

[0072] The upper end of the body portion 22 includes a square flange 32 (although it could be shaped otherwise) and such a flange can be used for mounting components associated with the sensor assembly 10, such as electronics suitable for processing sensor signals (analogue signals for example) close to the sensing source (to reduce noise), or electronics suitable for pre-processing of analogue signals to enable digital output. Current prototypes house suitable electronics within the body portion 22 to conduct signal processing and coversion to a digital output through a single plug at the top of the body portion 22, such as via CAN bus communication.

[0073] In other embodiments of the invention, it will be appreciated that further structure can be included with the sensor mount 12 for fixing it in relation to specific installations. For example, struts could extend laterally from the body portion 22 for connection to walls of a liquid collection container, or for connection to framework associated with the body of liquid. In some uses of the invention, the sensor assembly 10 might be immersed in a body of liquid that is not in a container, such as if the sensor assembly 10 is immersed in river or sea water. Other supporting arrangements may then be provided. These can include suspension or floating arrangements for example and for floating arrangements, the body portion 22 can be filled with a low density expanding foam that provides buoyancy.

[0074] The group or array of sensors 16 of Figure 1 is shown in isolation in Figure 10. The sensors 16 can be suitable to sense temperature, pH, ORP/redox, conductivity, metal ion concentration, dissolved oxygen concentration for example. Other sensors can be provided, and the arrangement of Figure 10 is an example only. The sensors 16 generally comprise a sensing device 17 that connects to a cable. Each sensing device 17 is specific to the characteristic being sensed and the sensed data transmits through the cable to suitable diagnostic equipment. The sensing devices 17 are located at the bottom end and form the sensing ends of the sensors 16 for immersion in a body of liquid and the form of sensor dictates the shape and configuration of the sensing devices 17. Various different shaped sensing devices 17 are shown in Figure 10 and each connects to a cable for data transmission, although it will be appreciated that wireless data transmission is also possible.

[0075] In the sensor apparatus 10, a portion of each of the sensing devices 17 and the cables of each sensor 16 that are connected to the sensing devices 17, is secured within the body portion 22 of the sensor mount 12 in a settable liquid. The settable liquid sets about the sensors 16 and fills the body portion 22 about halfway up from the bottom end 24 of the body portion 22. The upward extent of the settable liquid from the bottom end 24 is not particularly important other than sufficient settable liquid needs to be employed to secure the sensors 16 in position within the body portion 22 and to preferably ensure a liquid tight seal. The settable liquid secures the sensors 16 against movement relative to each other and the sensors 16 can be located relative to each other to minimise interference between them.

[0076] The sensors 16 are removed for illustrative purposes in Figures 7 and 9 (noting that in practice, once the settable liquid has been introduced into the body portion 22 about the sensors 16, the sensors 16 are not removable from the body portion 22) and show openings 36 in the settable liquid 38. These openings 36 are formed in accordance with the shape of the sensors 16 depending on whether the settable liquid forms about the enlarged sensing devices 17 or about the cables connected to the sensing devices 17.

[0077] Also included amongst the array of sensors 16 is a vibration device 34 (see Figure 10). The vibration device 34 is not a sensor, but when activated, can vibrate within the body portion 22 and within the settable liquid within the body portion 22, and vibrations are translated through the settable liquid to the sensors 16 and in particular, to the sensing portions or the sensing devices 17 of the sensors 16 that extend out of the bottom end 24 of the body portion 22. As explained earlier herein, the portions of the sensors 16 that extend out of the bottom end 24 of the body portion 22 are the sensing devices 17 that are exposed to liquid within the body of liquid and so those portions can be exposed to particulate within the body of liquid despite the provision of the filter assembly 14 to filter particulate material. The particulate can accumulate on the exposed portions of the sensing devices 17, and so the vibration device 34 is provided as a facility to dislodge that particulate by vibrating the sensors 16 and in particular the exposed, sensing devices 17 of the sensors 16. The vibration device 34 does not need to extend out of the bottom end 24 of the body portion 22, but rather, the vibration device 34 can terminate partially within or completely within the settable liquid in the body portion 22.

[0078] Returning to Figure 4, this shows the sensors 16 of the sensor array of Figure 10 located within the sensor mount 12 and shows the projection of the bottom, sensing devices 17 of the sensors 16 out from the bottom end 24 of the body portion 22. When the sensor assembly 10 is deployed in a body of liquid, the intention is that the upper level of the body of liquid extend upwardly to the bottom end 24 of the body portion 22, so that the bottom portions of the sensors 16 that extend from the bottom end 24 of the body portion 22, primarily the sensing devices 17, are completely immersed in the body of liquid. The upper level of the body of liquid can be above the bottom end 24 the body portion 22, but liquid from the body of liquid will be prevented from entering the interior of the body portion 22 either by the bottom end 24 of the body portion 22 being closed by a base, or by the bottom end 24 being closed by the settable liquid within the interior of the body portion 22, or both. It should be appreciated however, that ingress of liquid into the interior of the body portion 22 can be tolerated and so is not essential to prevent, as the sensors 16 can be suitably protected from the liquid of the body of liquid by suitable casing, sheathing or cabling. It is acceptable, for example, that the entire sensor apparatus 10 be immersed in a body of liquid as long as the sensors 16 have been suitably protected.

[0079] Figure 7 shows the bottom end 24 of the body portion 22 in perspective view while Figure 9 shows the body portion 22 looking through the open top end at the flange 32. As discussed above, these figures show precise voids 36 through which the sensors 16 travel through the settable fill material within the hollow interior of the body portion 22. Thus, the settable fill material 38 is shown with formed voids 36 which illustrate the passages through which the sensors 16 extend through the body portion 22. However, it should be appreciated that the voids 36 are not formed prior to the sensors 16 being inserted through the body portion 22, but rather, either the sensors 16 are inserted into the hollow interior of the body portion 22 first and thereafter the settable fill material 38 is introduced into the hollow interior to set about the sensors 16, or the settable fill material 38 is introduced into the hollow interior first and the sensors 16 are subsequently pushed through the settable fill material 38 before the fill material sets. Accordingly, it is important to understand that these voids 36 are not formed in a settable liquid for later introduction of the sensors 16, but rather, the voids 36 are formed by the settable fill material flowing around the sensors 16 either as it is introduced into the hollow interior of the body portion 22 in which the sensors 16 have already been installed, or as the sensors 16 or sensor cables push through it prior to setting. This allows the settable fill material 38 to fill all gaps within hollow interior about the sensors 16 and properly and securely locate the sensors 16 within the sensor mount 12.

[0080] In the illustrated embodiments, the settable fill material 38 fills the sensor mount 12 and holds the sensors 16 in position once the fill material 38 sets. The outer surfaces of the sensors 16 be shaped or can include suitable projections or openings to interact with the fill material 38 to lock into the fill material.

[0081] The tube 20 of the filter assembly 14 connects to the bottom end 24 of the sensor mount 12 by a friction fit and by keyway interaction with the body portion 22. Figure 4 illustrates a protruding key 40 positioned at the bottom end 24 of the body portion 22 and the upper edge 42 of the tube 20 includes a corresponding groove 41 (see Figure 7a) on the inside diameter thereof, for accepting the key 40. The key and groove extend axially and so it is a simple matter of pushing the tube 20 axially over the base 26 and the support 28 for the groove of the upper edge 42 of the tube 20 to engage the key 40. Once the key 40 is engaged, the tube 20 is located against rotation relative to the sensor mount 12, while the tube 20 is a tight, friction fit to the upper edge 42 with the bottom end 24 of the body portion 22.

[0082] As shown in Figure 3, the tube 20 is closed at the bottom end by the base 44. The diameter of the edge 46 of the base 26 of the sensor mount 12 is about the same as the inside diameter of the base 44, so that the edge 46 of the base 26 is a close or even friction fit within the tube 20 at the base 44. Figure 7 illustrates an opening 48 within the base 26 and this is provided to receive a boss or spigot which is upstanding from the inside surface of the base 44 of the tube 20 again, to locate the base 26 relative to the base 44 and to resist vertical movement between the tube 20 and the sensor mount 12. Figure 7a is a view of the Figure 3 arrangement but from the opposite end and shows the boss or spigot 49. The opening 48 can be a tight, friction fit with the boss or spigot 49.

[0083] The tube 18 and the tube 20 are preferably formed integrally and connect at the upper neck 50. This integral formation can be achieved by 3D printing, or by injection moulding for example. The tube 18 and the tube 20 could alternatively be formed separately and connected together, such as by threaded connection.

[0084] As indicated above, the provision of the pair of tubes 18 and 20 is to provide a cylindrical gap G between them to locate or capture a filter material so that liquid that travels through the tubes 18 and 20 will travel through the filter material and be filtered prior to arriving at or being exposed to the sensing devices 17 of the sensors 16. The types of relevant filter materials have been described in detail earlier herein. The gap G allows a filter material to be installed between the tubes 52 and 54 and to be removed for cleaning, or to be completely replaced, periodically as required.

[0085] A feature of each of the tubes 18 and 20 is therefore the openings or perforations that are formed in the cylindrical walls of the tubes 18 and 20 and these allow free flow of liquid through the tubes 18 and 20 to the inside of the tube 20 where the sensing portions of the sensors 16, the sensing devices 17, are located.

However, a major focus of the present invention has been to minimise the amount of particulate contained within the body of liquid reaching the inside of the tube 20 so that the particulate does not reach the sensors 16 to foul them such as by settling on them and affecting their sensing performance. Accordingly, the perforations or openings shown in the cylindrical walls 52 and 54 of the tubes 18 and 20 are formed in a way to minimise the likelihood of particulate settling within the openings so as to minimise the likelihood of that particulate subsequently travelling through to the inside of the tube 20 with flow of liquid through the openings or for the openings to become blocked or clogged. Each of the openings in the walls 52 and 54 is formed in a diamond shape with sloping edges 55 that resist particulate from settling on the walls, while the edges all slope outwardly from the inner diameter or inner surface of the tubes to the outer diameter or outer surface, again to promote travel of any particulate that lands on an edge of an opening to the outside of the respective tubes 18 and 20.

[0086] It is to be noted that with the sensor mount 12 extending into the tube 20 and with the bottom end of the tube 20 closed by the base 44, liquid can only access the inside of the tube 20 through the perforated side wall 54. Any liquid that enters the inside of the tube 20 thus will pass through the walls 52 and 54 and any filter material positioned between those walls. Despite this filtering, it is expected that particulate material that is sufficiently fine as to pass the tubes 18 and 20 and filter material sandwiched between those tubes, will flow into the inside of the tube 20, and that material will potentially settle on or foul the sensing devices 17 within the tube 20. To dislodge that particulate material from the sensing devices 17, the vibration device 34 can be operated periodically, or continuously and where such material is displaced from the surface of any of the sensing devices 17 by vibration, it will likely accumulate on the inside of the base 44 of the tube 20. This is acceptable, as there is sufficient volume for the shed particulate material to accumulate away from the sensing devices 17 of the sensors 16. However, this means that over time, particulate material may build up on the base 44 and so periodic cleaning of the sensor apparatus 10 may be required. Nevertheless, the expected build-up of particulate material is not expected to be great, particularly when used in column leaching facilities, and so the removal of particulate material from within the tube 20 is likely to be only necessary during standard scheduled maintenance.

[0087] The sensor apparatus 10 can carry electronics suitable for processing sensor signals close to the sensing source by mounting suitable electronics to the flange 32 or elsewhere, i.e. inside the body portion 22, while the sensors 16 can be connected to cabling for data transmission. Importantly, the sensing data is thus processed almost simultaneously as the data is collected or established. The sensor apparatus 10 is readily portable and the components are readily removed for cleaning or replacement. Prototypes created to date are also robust and capable of operation in aggressive environments.

[0088] Where any or all of the terms "comprise", "comprises", "comprised" or "comprising" are used in this specification (including the claims) they are to be interpreted as specifying the presence of the stated features, integers, steps or components, but not precluding the presence of one or more other features, integers, steps or components.

[0089] Those skilled in the art will appreciate that the invention described herein is susceptible to variations and modifications other than those specifically described. It is understood that the invention includes all such variations and modifications which fall within the spirit and scope of the present invention.