Sensor device for partially saturated porous media applications

Abstract

The present disclosure relates to a sensor device (10) positionable within the region of a porous medium (72) to acquire data from a liquid L within the porous medium (72). The apparatus (10) comprises a sensor housing (14) comprising an inlet (18) for receiving the liquid L from the porous medium (72) into the sensor housing (14) and an outlet (34) for the received liquid L out of the sensor housing (14). The apparatus (10) is configured for flowing the received liquid L through the sensor housing (14) along a predetermined flow path between the inlet (18) and the outlet (34). The sensor device (10) further comprises sensor means (38) located within the sensor housing (14) for acquiring flow data of the liquid L between the inlet (14) and the outlet (34). The sensor device (38) includes one or more sensors positioned along the flow path to contact the liquid L and configured to measure one or more properties of the liquid L to obtain data representative of the liquid L at the porous media region (72). The sensor device (10) further comprises a filtering device (86) configured for removing particles from the liquid L prior to contacting the one or more sensors.

Description

[0001] Priority Cross - Reference

[0002] This application claims priority to Australian Provisional Patent Application 2022902445, filed on August 26, 2022, the entire content of which is incorporated herein by reference. Technical Field

[0003] This application relates to in - situ continuous monitoring of physical and / or chemical parameters of liquids within porous media in industrial, environmental, and experimental processes. More specifically, the present invention relates to a sensor device for monitoring physical and / or chemical parameters of liquids in unsaturated or partially saturated porous media environments, such as in areas including heap leaching, in - situ leaching, stockpile leaching, soil remediation, material / energy recovery processes, and the migration and remediation of the aqueous phase in subsurface environments. The present invention also relates to laboratory equipment for simulating the above - mentioned environments and conditions, such as laboratory columns for simulating heap leaching. Background Art

[0004] The following discussion of the background of the invention is intended to facilitate an understanding of the invention. However, it should be understood that the discussion does not admit or recognize that any aspect of the discussion is part of the common general knowledge as of the priority date of the application.

[0005] Various experimental and industrial processes require monitoring of liquids within porous media. Heap leaching is an example of such an industrial process, in which a solvent liquid (usually an acid) is passed through a pile of crushed ore so that the liquid releases / dissolves the target mineral from the ore and is then collected at the bottom of the pile as "pregnant liquor" or concentrated leach solution (PLS) for further processing to isolate / extract the target metal.

[0006] Another example of porous media liquid monitoring is column leaching, which involves an experimental apparatus consisting of a vertical column containing a porous media, where a liquid leaching agent is poured onto the top of the column and passes through the media, and is again collected at the bottom of the column for subsequent analysis and recovery to measure or determine the degree of interaction between the media and the liquid. Column leaching has a wide range of applications, including being used as a test system for heap leaching applications and municipal water testing applications. Other example applications that require monitoring of porous media liquids include tank leaching and vat leaching, mine waste remediation, and soil remediation.

[0007] The problem with existing methods for testing and analyzing porous media liquids is that the testing of sample liquids is typically performed ex - situ after the liquid has been extracted or collected from the media. For example, sample liquids can be collected from within a ore pile and pumped to the surface for testing. Alternatively, liquids can be collected at the bottom of the pile (or column leaching apparatus) and then transported to a testing laboratory in a different part of the facility, or even off - site.

[0008] Since the chemical and physical properties of a sample liquid may change between sampling and testing, delays between sampling and analysis can introduce inaccuracies. For example, the oxygen reduction potential (redox) is a time-sensitive parameter, and thus the in-situ redox level of a sample may differ significantly from the redox level measured after removing the sample from the medium and exposing it to oxygen or air for a period of time prior to analysis.

[0009] In addition, off-site and off-site laboratory analyses take time, and there is a lag time between sampling, analysis, and taking action, which is not conducive to a timely response to environmental or process problems. In some cases, the act of extracting liquid from a porous medium may interfere with process parameters (e.g., excavation or introducing a sampling path or channel into a material pile). Summary of the Invention

[0010] Accordingly, it is desirable to provide an alternative sensor device for porous media applications that addresses at least some of the above disadvantages of existing systems, or provides an alternative option for operators of liquid monitoring and testing systems.

[0011] In one aspect of the present invention, there is provided a sensor device that can be positioned within a region of a porous medium for obtaining data from a liquid within the porous medium. The device includes: a sensor housing that includes an inlet for receiving liquid from the porous medium into the sensor housing and an outlet for allowing the received liquid to flow out of the sensor housing, the device being configured to cause the received liquid to flow through the sensor housing along a predetermined flow path between the inlet and the outlet; a sensor device within the sensor housing for obtaining data from the liquid flow between the inlet and the outlet, the sensor device including one or more sensors positioned in the flow path to contact the liquid and configured to measure one or more properties of the liquid to obtain data representative of the liquid at the region of the porous medium; and a filtering device configured to remove particles from the liquid before the liquid contacts the one or more sensors.

[0012] Advantageously, the present invention provides a sensor device that is configured to be positioned within a region of a porous medium to be analyzed and enables in-situ real-time acquisition of data regarding the liquid in that region. Compared to existing systems and devices that test samples after extracting them from a porous medium, the present invention provides the operator with up-to-date information regarding the chemical and physical properties of the liquid within the region of interest. In addition, the present invention can reduce the lag time between sampling and data acquisition, making the data obtained more representative of the liquid within the medium and reducing the chance of changes in the chemical or physical properties of the sample between sampling and testing.

[0013] Accordingly, the present invention can permit time - continuous monitoring of a liquid within a porous medium without the need to periodically obtain samples and transport the samples to a test laboratory. For example, the present invention can permit obtaining data from a liquid within a porous medium within seconds of entry into the inlet of the sensor housing and transmitting the data to a suitable receiving hub. The reduced lag time can provide more actionable information and can enable an operator to react more quickly to changing conditions within the porous medium in certain applications (such as industrial processes). Thereby, the present invention can also facilitate closed - loop process control.

[0014] The present invention advantageously permits a liquid received through an inlet to flow through the sensor housing between the inlet and the outlet and permits measurement of the liquid between the inlet and the outlet. At the outlet, the received liquid can typically return to the porous medium and continue its natural flow path. In this regard, the present invention is advantageously configured to not interfere with or disrupt the bulk flow field and typically samples and measures the liquid passing through the sensor housing and returns the measured liquid to the porous medium region. The size of the sensor device according to the present invention can also be relatively small to minimize interference within the flow field. For example, in a particular embodiment, the width of the sensor housing is 45 mm and the length is 80 mm.

[0015] The porous medium suitable for the present invention can be any such porous material through which a liquid flows and for which analysis of the liquid is desired. Depending on the application, examples of possible porous media can be mined ore, mined ore waste, crushed and / or agglomerated ore, soil, dirt, rock, industrial particles, industrial waste (including e - waste), coal, clay, or ash / fly ash.

[0016] The present invention is particularly applicable to systems for heap leaching or simulated heap leaching, such as, for example, crib or column leaching equipment. It can be understood that the heap leaching process involves placing crushed ore on a liner and then irrigating with a leaching agent to provide a leachate, which is then collected in a pond or tank. Depending on the ore, the location and type of the heap, environmental conditions, etc., many parameters in heap leaching will determine the effectiveness of the heap leaching, the metal dissolution rate, the amount of consumables used in the heap leaching, etc. Crib and column arrangements are mainly used to simulate and model large - scale heap leaching applications in a laboratory environment. Currently, the analysis of crib and column arrangements is limited to determining parameters after the leachate is extracted and collected at the bottom of the crib or column. This method provides only limited or even no insight into in - situ and real - time heap leaching operations. Therefore, the present invention can permit real - time insight into the heap leaching operation both spatially and temporally.

[0017] The present invention advantageously enables in-situ data to be obtained from a heap or from a tank or column leaching device before collecting leachate from the bottom of the column or heap. Thus, the present invention can provide insights to the operator that can inform adjustments to one or more parameters of heap leaching to improve operation. For example, the chemical properties of the fluid over time within a material region can be monitored, which can inform adjustments to chemical parameters to improve metal extraction from the ore. Similarly, data obtained from in-situ measurements of the liquid within the heap or column device can inform the optimization of physical parameters such as irrigation drip rate, oxidation flow rate, etc.

[0018] The present invention can allow for continuous monitoring of the bioleaching process and, in certain applications, can enable spatial monitoring of the bioleaching heap. For example, the sensor device of the present invention can be used in the monitoring system described in the applicant's prior international patent publication WO2018 / 068087, where multiple sensor devices can be distributed in a two-dimensional or three-dimensional spatial arrangement within a porous material (such as an ore heap) to obtain data from various regions within the bulk material heap.

[0019] The present invention can also be applied to smaller-scale leaching applications, such as tank leaching and cell leaching, as well as large-scale heap leaching. The present invention provides continuous spatial monitoring over time of the leaching heap and its chemical parameters. This in turn allows for real-time control of parameters in heap leaching, such as temperature, chemical parameters, chemical concentration (such as acid), air flow rate, liquid flow rate, aeration, irrigation spacing, etc. Advantageously, real-time control of these parameters can increase leaching recovery and efficiency, enable remedial measures to be taken in response to changes in the heap quickly, and reduce consumables (i.e., the materials used for leaching).

[0020] A particular advantage of the present invention is that it can be used in a partially saturated porous medium environment with non-steady state and slow flow. For example, an environment where liquid gradually penetrates through the medium (such as moist particles), for example, an irrigated leach solution slowly flowing downward through an ore heap. The present invention can advantageously create local saturation conditions within the device sensor housing to facilitate sensor measurements that otherwise cannot be made by the sensor in a partially saturated environment due to insufficient contact interface between the liquid and the sensor. In this regard, the device can be configured to perform a flow collection operation to collect, block / obstruct a limited amount of the received flow and direct it in a specific direction to enable or facilitate sensor measurements.

[0021] In this regard, embodiments of the present invention provide a device configured to be positioned within a region of a partially saturated porous medium and to create local saturation conditions for at least one sensor of the sensor device to facilitate data acquisition by the sensor device. Thus, the device can operate to collect liquid from the relatively slowly flowing liquid passing through the porous medium and block / obstruct a limited amount of the liquid at the sensor device to enable data to be obtained from the liquid.

[0022] According to an embodiment of the present invention, the flow between the inlet and the outlet is configured for gravity feeding, wherein the inlet is located at a higher level than the outlet, and the sensor device is located at a level lower than the inlet and higher than the outlet. For example, the inlet may be positioned on the upper side of the sensor housing and oriented to face upwards within the porous medium region. In one form of the present invention, the inlet extends along most of the upper side of the sensor housing, and wherein, in use, the inlet faces upwards. In a particular form of the present invention, the inlet has a planar configuration and is approximately horizontal in use.

[0023] In an alternative configuration, the liquid flow can be facilitated by means other than gravity feeding (such as capillary (i.e., "wicking") flow or via a pump). In this regard, it is contemplated that the inlet does not necessarily have to be located above the sensor device, but can be located at other positions relative to the sensor device and have an appropriate configuration to allow the liquid to be received or drawn in through the inlet and flow towards the sensor device.

[0024] In an embodiment of the present invention, the interior of the sensor housing provides a sensor chamber in which the sensor device is accommodated. In an embodiment, the inlet can be located above the sensor chamber, and in particular, vertically above the sensor chamber. The size, shape, or configuration of the inlet can be configured to maximize the amount of liquid received by the inlet and delivered to the sensor chamber. In an embodiment, the inlet is configured to occupy all or almost all or most of the upper side of the sensor housing. In an embodiment, the inlet is configured with an area approximately equal to the two-dimensional footprint of the sensor chamber. Thus, the inlet can be sized to span the entire length and width of the sensor chamber.

[0025] In an alternative embodiment that may be desirable for porous medium applications with particularly low liquid flow rates, the device can be provided with an area larger than the footprint of the sensor chamber. Alternatively, the device can include a collection means that has an area larger than the inlet and captures the collected liquid and directs it towards the inlet. For example, the device can include one or more collection members that extend outwards (and possibly upwards) from the inlet, which provide a collection area larger than the area of the inlet and are inclined relative to the horizontal to direct the collected liquid towards the inlet.

[0026] In an embodiment of the present invention, in the case where the fluid flow rate in the system is very low or abnormally low and may result in the formation of adverse saturation conditions in the sensing chamber, the inlet is configured to have a funnel shape or a ramp shape and extends to a region wider than the housing to capture and accumulate more liquid and maintain the correct local saturation conditions in the sensor chamber.

[0027] In addition to the sensor chamber below the inlet that houses the sensor device, the apparatus may include one or more additional chambers that house electrical components, such as a printed circuit board (PCB) or other electrical components, which are configured to receive electrical signals from the sensor and / or transmit sensor data to a connected receiving hub via a wired or wireless connection. The sensor chamber may be fluidically isolated (i.e., fluid-sealed) from the electrical component chamber to prevent sensitive electrical components from being exposed to leachate solutions or potentially corrosive liquids (such as the leachant in the porous medium and the sensor chamber).

[0028] The sensor device within the sensor chamber may be connected to a corresponding electrical component within the electrical component chamber via a data cable that extends through a wall or partition between the sensor chamber and the electrical component chamber. In an alternative configuration, one or more sensors may extend through a wall or partition between the sensor chamber and the electrical component chamber such that the sensing portion of the sensor is located within the sensor chamber to be exposed to the received liquid, and the non-sensing portion or other portions of the sensor are located within the electrical component chamber.

[0029] The electrical component chamber may include electronics configured to convert analog signals received from one or more sensors into digital signals. In embodiments where the sensor device of the present invention includes a dissolved metal ion sensor, the chamber may include a local PCB with electronics configured to perform electrochemical or optical measurements required for dissolved metal ion and dissolved oxygen sensing.

[0030] The outlet may be located at the base of the sensor housing, such as at the base of the aforementioned sensor chamber, such that liquid flows generally downward through the sensor chamber and out the outlet. In one form of the present invention, the outlet is configured to facilitate the accumulation of a relatively small amount of liquid at the outlet. In a particular embodiment, the area of the outlet is smaller than the area of the inlet to delay the outflow of fluid from the sensor housing. The relatively small outlet area may restrict or impede or block the flow rate of the outflowing fluid and cause the accumulation of liquid upstream of the outlet. This configuration may facilitate the operation of certain types of sensors that require exposure to a large amount of fluid or more saturated conditions or are optimized therefor. Thus, this configuration may be desirable in certain fluid monitoring applications and not necessary in others. The ratio of the outlet area to the inlet area may also vary depending on the application and the amount of fluid accumulation (if any) desired.

[0031] In a particular form of the present invention, the sensor device includes a conductivity sensor located at the base of the sensor housing. The conductivity sensor may be positioned to be exposed to a pool of liquid at the base of the housing. In use, the conductivity sensor may be partially surrounded or potentially submerged in the pool of liquid at the outlet.

[0032] The configuration of the sensor housing can be such that the sensor chamber within the sensor housing is sealed relative to the porous material, except for the inlet and outlet. For example, the sensor housing may have no other external openings except for the inlet and outlet. In this way, in use, potentially corrosive and erosive liquids and chemicals present in the porous material are only allowed to pass through the housing via the inlet and only via a predetermined flow path. Thus, the device can be configured to manage or control the exposure of the sensor device to (potentially erosive) liquids for analysis. The flow path allowed to pass through the sensor housing can be configured / designed or customized such that a particular sensor is in direct contact with the received liquid and other sensors are kept out of direct contact.

[0033] In this regard, the sensor device can include one or more sensors that do not come into contact with the flow path. For example, sensors that can operate under fully unsaturated conditions. The sensor device can include a temperature sensor spaced apart from the flow path and configured to measure the internal temperature within the sensor chamber, which is similar to the temperature of the liquid within the porous medium and thus also similar to the temperature of the porous medium (e.g., the temperature of the stack). In an alternative embodiment, the temperature sensor can be placed in direct contact with the liquid flow or almost in direct contact with the liquid.

[0034] In a particular embodiment of the present invention, the device is provided with guiding means configured to direct the liquid received through the inlet towards the sensor device. The guiding means can be configured to direct or converge the received liquid towards the sensor device. The guiding means can be configured to converge the received liquid at a particular location, such as a particular location on the sensor device. The predetermined flow path provided by the device can be at least partially managed by the guiding means, which can help to direct or facilitate the flow through the sensor housing along a preferred flow path.

[0035] In an embodiment of the present invention, the guiding means is located between the inlet and the sensor device and is configured to converge the liquid collected from the inlet towards the sensor device. For example, the guiding means can operate to converge the received liquid collected across a larger volume or area through a relatively smaller gap or channel in order to direct the received liquid towards the sensor device and in order to maximize the volume of liquid available for measurement at the sensor device. Thereby, the guiding means can operate to increase or maintain saturated conditions at the sensing site and enable the sensor to operate correctly.

[0036] The guiding device can have various configurations. In a particular embodiment of the present invention, the guiding device includes at least one inclined surface that extends below the inlet and terminates at a lower edge oriented towards the sensor device, wherein, in use, the liquid flow is collected or formed on the inclined surface and flows towards the lower edge and from the lower edge towards the sensor device. The inclined surface can be curved or can form part of a conical structure. Alternatively, in a particular form of the present invention, the inclined surface is generally planar.

[0037] Thus, the inclined surface can provide such a surface below the inlet: the liquid received through the inlet is collected at this surface and then flows downward under the influence of gravity towards the lower edge of the inclined surface, and then it can immediately contact the sensor device, or can fall (e.g., drip or flow) from the lower edge onto the sensor device.

[0038] In a particular form of the present invention, the guiding device includes a pair of inclined surfaces. For example, the lower edge of the first inclined surface can terminate above the second and lower inclined surface, so as to guide the liquid collected on the first inclined surface to the second inclined surface and then towards the sensor device. The first and second inclined surfaces can extend below separate portions of the inlet, such that the entire inlet is located above one or both of the inclined surfaces. This configuration can advantageously allow the received fluid to be collected on one or both of the inclined surfaces across the entire width of the inlet, and depending on the length and position of the lower one of the two inclined surfaces, guide the fluid to the sensor device at various positions within the sensor housing.

[0039] In a particular form of the present invention, the sensor housing includes one or more internal crossbars for supporting the fluid guiding device. For example, the sensor housing can be provided with a pair of internal crossbars at the upper portion of the sensor chamber, which are configured to each support one of a pair of inclined surfaces of the guiding device. The crossbars can be provided at different levels within the sensor chamber to correspond to different levels of the inclined surfaces. The sensor housing can be generally elongated. Thus, the internal crossbars and the inclined surfaces of the fluid guiding device can also be generally elongated.

[0040] As described above, one or more sensors of the sensor device are located at the flow path for contacting the liquid in order to obtain sensor data from the liquid. Depending on the number and type of sensors provided in the sensor housing, which may depend on the particular liquid monitoring application, a predetermined flow path can be configured to flow over or past one or more sensors at a sufficiently high volume or flow rate to ensure accurate sensor performance. However, according to a particular embodiment of the present invention, the device may include a wetting material in contact with the one or more sensors of the sensor device, the wetting material being positioned within the flow path and configured to maintain a wet or saturated condition at the one or more sensors in order to facilitate the one or more sensors in measuring one or more properties of the liquid.

[0041] In cases where the flow rate is too low or inconsistent, the wetting material can advantageously ensure that the sensors remain in a saturated condition to provide the necessary sensor saturation required for accurate sensor operation. Thus, in all applications such as those where the flow rate within a porous medium is sufficiently high, a wetting material may not be required. In addition to facilitating saturated conditions at low flow rates, the wetting material can also advantageously increase the saturated area available for measurement, thereby enabling the use of additional sensors and / or optimizing the physical arrangement / position of the sensors.

[0042] For example, in a particular embodiment of the present invention, the sensor device includes a plurality of sensors in contact with the wetting material, wherein at least one sensor contacts a first side of the wetting material and at least one sensor contacts a second, opposite side of the wetting material. The first and second sides of the wetting material can be, for example, an upper side and a lower side. Thus, the wetting material can facilitate positioning of sensors on respective sides of the wetting material, thereby providing an increased saturated surface area available for sensor measurement. The wetting material can be positioned in a gap or space between sensors on opposite sides of the flow path. The wetting material can have a generally elongated shape and, in particular, can have a generally planar, elongated shape.

[0043] The wetting material can have a material configuration that allows the liquid to be distributed throughout the wetting material via capillary action, but at the same time also allows the flow to continue through the wetting material and allows the flow to exit the lower side of the wetting material and continue along the flow path towards the outlet.

[0044] Therefore, it should be understood that the liquid "flow" referred to herein is intended to encompass relatively slow-moving and non-steady-state flows such as diffusion or capillary flow or wicking.

[0045] The wetting material can have further advantages as it can be configured as part of the filtration device to remove relatively fine particles (solids, such as fine powders and clays) from the liquid. This aspect will be discussed in more detail later when the filtration device is described in more detail.

[0046] Depending on the particular liquid monitoring application for which the sensor device is targeted, the sensor device can include one or more of a variety of sensors. The sensor device can include one or more of a pH sensor, a dissolved metal ion sensor, a temperature sensor, a redox potential sensor, a dissolved oxygen sensor, or a conductivity sensor. In a particular form of the present invention, the sensor device includes all six of these sensor types. In a particular form of the present invention, one or more of the six sensor types can include a plurality of discrete sensors. For example, a plurality of metal ion sensors can be provided to detect various metal ions. Thus, it should be understood that the sensor device can include more than six sensors.

[0047] It should be understood that the sensor can take any suitable form depending on the physical and / or chemical phenomenon to be measured, such as ion-selective electrodes, voltammetric electrodes, amperometric sensors, and optical sensors, such as dissolved metal ion, dissolved oxygen, and sulfide sensors.

[0048] The sensor device can include a reference electrode, wherein one or more sensors of the sensor device are associated with the reference electrode. The present invention can utilize any suitable reference electrode having sufficient chemical stability, acid resistance, thermal stability, and mechanical stability. In a particular form of the present invention, the sensor device includes a solid-state reference electrode, which provides improved lifetime, robustness, and resistance to chemicals, high temperatures, and mechanical shock. The solid-state reference electrode can take any form, such as the type described in the applicant's earlier international patent publication WO2018 / 201200.

[0049] The reference electrode can be used in combination with one or more sensors for electrochemical measurements. In one form of the present invention, the reference electrode is associated with the pH sensor in the sensor device for measuring the pH value of the received liquid.

[0050] In an embodiment of the present invention, the sensor device includes a solid-state pH sensor. A typical pH sensor is an ion-selective glass electrode, which usually has an internal reference electrode. Glass pH electrodes have a high impedance and require special electronics to record signals - they also exhibit an alkaline error in high pH environments and an acid error at very low pH values. They are also fragile and require constant calibration due to drift and instability. In addition, some solid-state sensors (such as ion-sensitive field-effect transistor ISFET sensors) are also affected by drift and hysteresis effects and are light-sensitive. Since the operating environment of the present invention is harsh, the use of a solid-state pH sensor may be particularly desirable. The solid-state pH sensor can be in any form and can be, for example, of the type of metal oxide pH sensor described in the applicant's earlier international patent publication WO2016 / 033632.

[0051] In a particular form of the present invention, the sensor device includes a pH sensor configured to measure the pH value of the received liquid, and the pH sensor is positioned along the lower side of the flow path. The pH sensor may include a sensing surface having an inclined orientation configured to cause the liquid flow to move above the sensing surface. In one form of the present invention, the direction of the flow path above the sensing surface is diagonally downward through the sensor housing. In a particular embodiment, the sensing surface is oriented at an angle of approximately 30° to the horizontal direction (and also at 30° to the planar inlet of the sensor housing). It should be understood that various inclinations / orientations are possible. The inclination of the sensing surface of the pH sensor promotes the downward flow of the fluid and across the sensing surface, thereby reducing or eliminating flow stagnation, which may lead to precipitate formation and / or may start to compromise data accuracy as the sensor is no longer exposed to newly received liquid from within the porous region. Various configurations or geometries of the pH sensor and the sensing surface of the pH sensor can be envisioned. In an embodiment, the sensing surface of the pH sensor is curved, for example, arcuate. In a particular embodiment, the pH sensor has a cylindrical configuration. In a particular embodiment, the sensing surface of the pH sensor is cylindrical or configured as a section of a cylinder. In an alternative embodiment, the sensing surface of the pH sensor is generally planar.

[0052] In an embodiment of the present invention, the sensor device includes one or more additional sensors spaced apart from the sensing surface of the pH sensor by a gap, and the flow path extends through the gap between the sensing surface and the one or more additional sensors. In a particular embodiment of the present invention, the solid-state reference electrode and the dissolved metal ion sensor are positioned along the upper side of the flow path. The solid-state reference electrode and the dissolved metal ion sensor may be positioned on the side of the flow path opposite to the sensing surface of the pH sensor. The sensor device may further include a redox sensor positioned along the upper side of the flow path.

[0053] In an embodiment of the present invention, a wetting material may be located on the sensing surface of the pH sensor. The shape or size of the wetting material may be configured to extend along most or substantially all of the sensing surface. Thus, the wetting material may be inclined at the same inclination as the sensing surface and, in particular, may be inclined at about 30° with respect to the horizontal direction during use. The received liquid may thus flow obliquely downward through the wetting material. In this regard, the upper end of the wetting material may be the 'upstream' side of the wetting material, while the lower end of the wetting material may be the 'downstream' side of the wetting material. The upstream end of the wetting material may be located at or may cover the upper portion of the sensing surface, and the downstream end of the wetting material may be located at or may cover the lower portion of the sensing surface.

[0054] In an embodiment of the present invention, the upstream end of the wetting material is located below (e.g., vertically below) the guiding device such that the guiding device converges the flow onto the upstream end of the wetting material. For example, the lower edge of the inclined surface of the guiding device may be vertically positioned above the upstream end of the wetting material such that the received liquid will drip or flow from the guiding device onto the wetting material.

[0055] Subsequently, the received liquid may diffuse through the wetting material and provide / create saturated conditions for all sensors in contact with the wetting material to facilitate the sensors to measure the liquid properties.

[0056] The wetting material can filter fine particles by allowing the diffusion of liquid rather than solid particles. In this way, the fluid can pass through the wetting material from the upstream (i.e., upper) end of the wetting material to the downstream (i.e., lower) end of the wetting material, while the particulate matter is captured by the wetting material and generally does not diffuse towards the outer surface of the wetting material where the sensor is located. Thus, the wetting material can serve to prevent or reduce the exposure of the sensor to the fine particles that have passed through the first and second filters. The sponge filter is a combination of hydrophobic fibers and hydrophilic fibers. The mass ratio is adjusted to allow the liquid to reach the sensor surface for sensing, but also not to block the liquid for too long and miss the changes in the body. The filter material can be the following materials themselves or mixtures: nylon, polypropylene, polycarbonate, polyester, viscose cellulose ester, PMMA, Teflon, HDPE, fiberglass, quartz fiber, and graphite polymer mixed filtration or membrane materials.

[0057] The downstream end of the wetting material can be located at a level higher than the outlet. In a particular form of the present invention, the outlet can be located at the base of the sensor housing. The downstream end of the wetting material can be located above the base such that the fluid leaving the downstream end of the wetting material will flow or drip from the downstream end towards the base under the influence of gravity.

[0058] The present invention advantageously is provided with a filtering device to prevent or reduce the entry of particles from the porous medium into the sensor housing, which over time may contaminate or damage the sensor or impede the flow path of the liquid through the sensor housing. The filtering device is advantageously configured to remove particles (i.e., remove at least some particles) from the liquid before the liquid contacts one or more sensors. It should be understood that the function of the filtering device is to reduce or minimize the amount of particles to which the sensor is exposed. Thus, it should be understood that the filtering device does not necessarily need to remove all particles and a certain level of relatively small particles may still remain that have passed through the filtering device. In such a case, compared to the amount of particle exposure of the sensor without the filtering device, the filtering device has served to reduce the particle exposure of the sensor.

[0059] The filtering device can take a variety of configurations. In an embodiment of the present invention, the filtering device includes a first-stage filter located at the inlet and configured to prevent relatively large particles from entering from the porous medium. In a particular embodiment, the first-stage filter includes a rigid mesh located at the inlet, the rigid mesh including openings sized to prevent particles having a width or diameter greater than about 2 millimeters from entering. In one form of the present invention, the rigid mesh includes a plurality of inlet openings that only allow liquid and particles of a small enough size to be received into the sensor housing. The inlet openings can be sized to prevent relatively large-sized particles within the porous medium from entering.

[0060] Thus, the rigid mesh can act as a primary filter for large-sized particles but allows liquids and smaller particles to enter the sensor housing. In an embodiment of the present invention, the rigid mesh is integrally formed with the sensor housing. The inlet opening of the rigid mesh can have various shapes or configurations, such as being circular, or can be square, triangular, or diamond-shaped. The width or diameter of the inlet opening can have an average size of about 1 to 2 millimeters. In an embodiment of the present invention, the average size of the inlet opening is approximately 2 millimeters in length × 2 millimeters in width, or alternatively, the diameter is approximately 2 millimeters.

[0061] The rigid mesh can have a generally planar configuration, and the plane of the rigid mesh is substantially horizontal in use to capture the liquid moving downward within the porous medium. The inlet opening of the rigid mesh provides a passage that is approximately vertical or substantially perpendicular to the plane of the rigid mesh.

[0062] As previously described, the inlet can be provided with an area spanning the entire footprint of the sensor chamber within the sensor housing. Thus, the rigid mesh can be sized to span the width and / or length of the sensor chamber. The rigid mesh can extend all the way or substantially all the way to one or more sidewalls of the sensor housing. The rigid mesh can cover the entire or substantially the entire top side of the sensor housing.

[0063] In an embodiment of the present invention, the filtering device includes a multi-stage configuration for removing particles of different sizes. In a particular embodiment, the filtering device includes a second-stage filter configured to filter the material that has passed through the first-stage filter and remove particles smaller in size than those removed by the first-stage filter. The second-stage filter can be located below the first-stage filter. In an embodiment of the present invention, the second-stage filter is located vertically below the first-stage filter. The second-stage filter can have an elongated configuration and can extend substantially horizontally along the bottom surface of the first-stage filter. The second-stage filter can be sized to extend across all or substantially all of the bottom surface of the inlet. In this way, all the material passing through the first-stage filter can be received by the second-stage filter.

[0064] The second-stage filter can be a sponge or sponge-like filtering material. The second-stage filter can include a nylon sponge filtering material. The second-stage filter can have an elastic configuration that allows the second-stage filter to be elastically compressed, and thus the second-stage filter is elastically compressed into the volume of the sensor chamber below the inlet. The size, shape, elasticity, or other parameters of the second-stage filter can be configured for insertion into the upper portion of the sensor chamber within the sensor housing. The second-stage filter can be configured to remove particles having a size in the range of 10 micrometers to 2 millimeters.

[0065] The filter material can be the following materials themselves or mixtures: nylon, polypropylene, polycarbonate, polyester, viscose cellulose ester, PMMA, Teflon, HDPE, glass fiber, quartz fiber, and graphite polymer hybrid filtration or membrane materials.

[0066] The secondary filter can include one or more of the following materials: nylon, polypropylene, polycarbonate, polyester, viscose cellulose ester, PMMA, Teflon, HDPE, glass fiber, quartz fiber, and graphite polymer hybrid filtration or membrane materials. The material for the secondary filter can be selected to withstand the specific nature of the leaching solution of the leaching agent used in the intended application of the sensor device.

[0067] In an embodiment of the present invention, the filtering device includes a tertiary filter that is configured to filter the liquid that has passed through the secondary filter and remove particles smaller in size than those removed by the secondary filter. The tertiary filter can be configured to remove particles having a size in the range of <1 micron to 100 microns.

[0068] In an embodiment of the present invention, the tertiary filter is provided with an anti-fouling property to reduce or resist biofouling at the sensor device. The tertiary filter can be provided with anti-fouling fibers selected for bactericidal and / or fungicidal and / or algicidal properties. For example, the tertiary filter can include silver-based fibers or silver-based compounds to provide an inhibitory effect on microbial growth at or near the sensor device. The tertiary filter can include a composite of different materials that are selected to provide specific filtration and / or wetting and / or liquid diffusion and / or anti-fouling properties to the filter. The tertiary filter can include a nylon or wool sponge-type structure with anti-fouling fibers incorporated.

[0069] The tertiary filter can include a combination of hydrophobic and hydrophilic fibers. In a particular embodiment, the mass ratio can be configured to allow the liquid to reach the sensor surface for sensing, but also not impede or restrict the flow of the liquid through the filter. The filter material can include one or more of the following materials: nylon, polypropylene, polycarbonate, polyester, viscose cellulose ester, PMMA, Teflon, HDPE, glass fiber, quartz fiber, and graphite polymer hybrid filtration or membrane materials.

[0070] In an embodiment of the present invention, the second-stage and / or third-stage filters may have chemical or physical properties that enhance the selective capture or adsorption of specific particles. For example, the second-stage and / or third-stage filters may include a positively or negatively charged material configured to electrostatically adsorb negatively or positively charged particles. The second-stage and / or third-stage filters may be provided with hydrophobic properties to attract hydrophobic particles (and vice versa). In another example, the second-stage and / or third-stage filters may be provided with a specific chemical coating that allows for chemisorption or chelation of specific particles with certain surface chemistries. In another example, the second-stage and / or third-stage filters may be coated with a specific surfactant or flocculant that aids or promotes the aggregation of ultrafine particles into larger agglomerates of sufficient size to be captured by the second-stage and / or third-stage filters. The second-stage and / or third-stage filters may have a specific morphology (e.g., sponge particle shape), porosity, or surface area to facilitate the interception, capture, or attraction of specific particles of a specific shape, size, or molecular structure.

[0071] In a particular embodiment, one or more of the above filter characteristics are provided in the second-stage filter and one or more different filter characteristics of the above are provided in the third-stage filter. For example, some of the above filter characteristics may be more compatible with the second-stage filter configured to capture less fine particles compared to the third-stage filter that is more likely to become blocked. In a particular non-limiting example, the second-stage filter (but not the third-stage filter) may be coated with a flocculant to aid or promote the aggregation of particles.

[0072] As described above, a wetting material may be used to promote saturation conditions at one or more sensors, and in a particular form of the present invention, the wetting material may be configured as part of the filtration device. In a particular embodiment, the third-stage filter of the filtration device is provided by the wetting material. Thus, the wetting material may be configured to act both as a filter for relatively fine particles and as a material for infiltrating or wetting a diffusing liquid (e.g., via capillary flow) to promote a moist or saturated condition at one or more sensors. For example, to moisten the sensor surface in contact with the wetting material. The wetting material may be configured with a third function of inhibiting biofouling as long as it can be provided with antifouling properties of the above type.

[0073] The physical or material properties of the wetting material with a desired diffusion level may be selected to promote or maintain a desired humidity or saturation to facilitate sensor operation while also having a desired level of permeability that allows flow through the wetting material and continuation along the flow path towards the outlet.

[0074] In an embodiment of the present invention, the outlet can be provided by a rigid mesh structure. The outlet mesh structure can include a plurality of outlet openings that allow liquid to flow out of the sensor housing while preventing relatively large particles from entering via the outlet, for example, during installation of the sensor device into a porous medium.

[0075] From the discussion of the above filtration device, it can be understood that the sensor device according to the present invention can be configured to be submerged or buried within a porous medium. The region of the porous medium where the sensor device is located can be below the surface of the porous medium. According to an embodiment of the present invention, the entire sensor device can be configured to be buried or submerged within a porous medium.

[0076] The sensor housing can be formed from a variety of materials, and the material selected can vary depending on the intended application of the sensor device, particularly depending on whether the device is intended to be used in an erosive or corrosive environment. In a particular form of the present invention, the housing includes a corrosion-resistant polymer material. In a particular embodiment, the sensor housing is formed from a polycarbonate material. In a particular form of the present invention, the sensor housing includes a metal material. For example, a corrosion-resistant metal material. In a particular form of the present invention, the sensor housing includes a titanium material, such as a titanium alloy material. In a particular form of the present invention, the housing is formed via additive manufacturing. Using additive manufacturing can facilitate custom production of the rigid mesh structures for the housing inlet and housing outlet and can allow the inlet and outlet to be integrally formed with the sensor housing. In a particular embodiment, the sensor housing is produced via additive manufacturing of a metal material.

[0077] In a particular embodiment, the sensor housing includes a strengthening or reinforcing means. More specifically, the sensor housing can include strengthening ribs to reinforce the housing against the relatively high loads when used in high ore pillars. In a particular embodiment, the strengthening ribs are formed from stainless steel. The strengthening ribs can be fully encapsulated within the polycarbonate material of the sensor housing. In a particular embodiment, the sensor housing is formed by additive manufacturing (e.g., 3D printing) having voids that are configured for subsequent insertion of the strengthening ribs and then sealed with resin.

[0078] In a particular form of the present invention, the sensor housing can be selectively opened to enable access to the sensor chamber. This configuration can advantageously allow access to the sensor chamber to inspect, clean, maintain, repair, or replace the sensor or other internal components, such as a secondary filter or wetting material. For example, if the secondary filter and wetting material become blocked with filtered particles over time, cleaning or replacement is required.

[0079] The sensor housing can be configured with removable components, such as a removable lid or end. In a particular embodiment, the sensor housing can include a removable end. In one form of the invention, the removable end includes fluid guiding means such that removal of the removable end also removes the fluid guiding means from the sensor housing. For example, one or two inclined surfaces of the fluid guiding means can extend from the removable end and can in particular be integrally formed with the removable end.

[0080] Thus, in an embodiment of the invention, the guiding means can be removed from the sensor housing. In an alternative embodiment, the guiding means can be integrated with the sensor housing. For example, the guiding means can be non-removably integrated with the sensor housing. In particular, the guiding means can be integrally formed with the sensor housing, and the inclined surface can be integrally formed with the wall of the sensor housing.

[0081] The device can be provided with a suitable sealing configuration at the interface between the removable end and the remainder of the sensor housing. The engagement between the removable end and the remainder of the sensor housing can be provided by an interference fit, a snap fit, a locking mechanism, a clamping mechanism, or any other mechanism or configuration suitable for allowing selective disconnection and then reconnection between the removable end and the remainder of the housing.

[0082] From the above, it can be understood that embodiments of the present invention advantageously provide a sensor device that is configured to receive a relatively limited liquid flow in a porous medium and guide the received fluid along a managed flow path, aiming to maximize the fluid availability for sensor measurement. In certain embodiments, the predetermined flow path can include:

[0083] a. Entering through the sensor housing inlet, which also operates as a first-stage filter to prevent relatively large particles from entering;

[0084] b. Passing through a second-stage filter, which is configured to filter medium-sized particles from the liquid;

[0085] c. Passing through a diversion device, which is configured to direct the liquid leaving the second-stage filter towards the sensor device, particularly towards the upstream end of the wetting material located on the sensing surface of the pH sensor;

[0086] d. The liquid diffuses through the wetting material to bring one or more sensors arranged in contact with the wetting material to a more saturated condition;

[0087] e. Passing through the downstream end of the wetting material and then blocking / obstructing the liquid at the housing base adjacent to the outlet;

[0088] f. Flow out through the sensor housing outlet and return to the porous medium, particularly the porous medium portion below the sensor housing.

[0089] As can be understood from the above, the predetermined fluid flow path allows the sensor device to be configured according to the specific requirements / applications of certain sensors. For example, certain sensors that require wet or saturated operating conditions can be positioned in contact with the wetting material or at the base of the housing. The sensor can be positioned on the opposite side of the wetting material to utilize the saturated surface area of the wetting material. Other sensors that do not require direct contact with the liquid can be positioned at other locations within the sensor housing.

[0090] It can also be understood from the above discussion that embodiments of the present invention are configured to maintain liquid flow through the sensor housing (e.g., via the inclined pH sensor and the wetting material) to prevent or minimize the occurrence of stagnant zones that may promote contamination and result in measuring liquid samples that were not recently collected from the porous medium and may thus not represent the true characteristics of the liquid flowing through the porous medium at that time.

[0091] Accordingly, embodiments of the present invention provide near real-time data acquisition of the chemical and physical properties of liquid samples, which are received in-situ as compared to non-in-situ liquid samples (e.g., samples collected at the bottom of a column or heap), and are thus more representative of the true conditions within the porous medium, as the properties of the liquid may change since leaving the porous medium.

[0092] In addition, in certain applications, the properties of the liquid may change after leaving the region of the porous medium that needs to be analyzed. For example, in certain applications, it may be desirable to obtain liquid data from a relatively shallow region of a ore heap and before the liquid has passed through the entire depth of the ore heap and been collected at the bottom. The present invention can allow data to be collected at different depths within the porous material and enables comparison of liquid properties across the changing spatial aspects of the bulk porous medium.

[0093] In this regard, another aspect of the present invention provides a system for obtaining data from a liquid in a heap leaching application, the system comprising a plurality of the above-described sensor devices, wherein the sensor devices are distributed throughout the regions of the heap leaching material to be analyzed, and the sensor devices are configured to obtain sensor data regarding the liquid within the region of each sensor device and transmit the sensor data to one or more hubs. For example, a plurality of sensor devices according to the present invention can be positioned at different regions corresponding to different depths of the stacked material in order to obtain in-situ data from discrete regions.

[0094] Another aspect of the present invention can provide a column leaching device, the column leaching device including a straight column having a peripheral wall, the peripheral wall including an opening, and the column leaching device further including the sensor device as described above, wherein the sensor device extends through the opening in the peripheral wall and into the interior of the column. The opening of the straight column can be configured to receive the sensor housing and provide a seal between the edge of the opening and the sensor housing. In a particular embodiment, a part of the sensor device (such as the sensor housing) can be located inside the column, while a part of the sensor device (such as the electrical component chamber) can be located outside the column and connected to a receiving hub via one or more data cables, the receiving hub being configured to receive data about the liquid inside the column from the sensor housing.

[0095] In some columns in a laboratory environment, an external water jacket is arranged around the column for facilitating the conveyance of a hot fluid or a cold fluid (mainly using water) around the column to maintain a specific temperature inside the column. In this embodiment, the sensor device can be configured to extend through the jacket lining and into the column as described above without causing any interference or perturbation to the jacket heating system or fluid flow.

[0096] Another aspect of the present invention can provide a method for obtaining data from a liquid inside a porous medium to be analyzed, the method including the steps of: positioning one or more of the above-described sensor devices inside the porous medium, the one or more sensor devices being configured to periodically obtain sensor data related to the chemical or physical properties of the fluid around the sensor over a predetermined period of time, and periodically transmitting the sensor data to one or more hubs via a data link. For example, the sensor data can be collected and transmitted in the manner described in the applicant's earlier international patent publication WO2018 / 068087. BRIEF DESCRIPTION OF THE DRAWINGS

[0097] The present invention will now be described with reference to the accompanying drawings, which illustrate preferred embodiments of the present invention, wherein:

[0098] Figure 1 is a perspective view of a sensor device and a column leaching device according to an embodiment of the present invention;

[0099] Figure 2 is Figure 1 a perspective view of the sensor device and the column leaching device in

[0100] Figure 3 after the sensor device is inserted into the column leaching device; Figure 1 and Figure 2 is a perspective view of the sensor housing of the sensor device in

[0101] Figure 4is a bottom view of the sensor housing in the previous figures, illustrating the base of the sensor housing;

[0102] Figure 5 is an end view of the sensor housing in the previous figures, with the end cap removed;

[0103] Figure 6 is an exploded view of the sensor housing in the previous figures, illustrating the insertion of the end cap into the sensor housing;

[0104] Figure 7 is a sectional end view of the sensor device in the previous figures located within a porous medium;

[0105] Figure 8 illustrates Figure 7 the sensor device in

[0106] Figure 9 through which liquid within the porous medium flows;

[0107] Figure 10 illustrates the use of the sensor device in the previous figures within a column leaching apparatus; and DETAILED DESCRIPTION

[0108] Figure 1 and Figure 2 illustrate the sensor device 10 and the column 12 of the column leaching apparatus. The sensor device 10 includes a sensor housing 14 configured to be inserted through an opening 16 in the column 12. Figure 1 illustrates the sensor device 10 removed from the column 12.

[0109] Figure 2 illustrates the sensor device inserted into the column 12 such that the sensor housing 14 is located inside the column 12. A portion 13 of the sensor device 10 remains outside the column 12 and will be discussed in further detail Figure 9 below.

[0110] Figures 3 to 6 Provides various closer views of the sensor housing 14.

[0111] Referring to Figure 3, the sensor housing 14 includes an upward-facing inlet 18 that is occupied by a rigid mesh 20. The rigid mesh 20 has a generally planar configuration and includes a plurality of openings 22 to allow liquid to pass through the rigid mesh 20 and into the sensor housing. The openings 22 are sized to prevent relatively large solids (such as stones, rocks, or clods of earth or dirt, ore, clay, etc.) from entering. Thus, the rigid mesh 20 is configured as a first-stage filter to prevent or limit relatively large particles from entering the porous medium where the sensor housing is located during use.

[0112] The sensor housing 14 and the inlet 18 can generally be used in the orientation shown in the illustrated embodiment, where the inlet is oriented generally horizontally. Thus, herein, the inlet 18 can be described as being oriented upward or upward-facing. When the inlet 18 is in a horizontal orientation, the area of the inlet 18 perpendicular to gravity is maximized to maximize the amount of liquid that can be collected through the inlet 18 from within the porous medium, which is drawn downward through the medium under the influence of gravity.

[0113] As Figure 3 shown, the area of the inlet 18 occupies all or almost all or most of the upper side of the sensor housing 14. As best illustrated with reference to Figure 7 , the inlet 18 is configured to have an area approximately equal to the two-dimensional footprint of the sensor chamber 24 within the sensor housing 14. In the particular embodiment shown, the inlet 18 is sized to span the entire length and width of the sensor chamber 24. Returning to Figure 3 , the upper side of the sensor housing 14 can be configured to have only a thin bevel or edge 26 around the rigid mesh 20 to again maximize the amount of liquid received through the inlet 18 from the porous medium.

[0114] The sensor housing 14 has an inverted arch profile that has a flat or planar upper side consisting essentially of the inlet 18 and a curved base 28. The sensor housing 14 includes a pair of generally planar wall portions 30 located on opposite sides of the sensor housing 14, and the pair of wall portions 30 are connected by the curved base 28. Figure 3 Only one of the wall portions 30 is visible in Figure 6 . Thus, the wall portions 30 and the curved base 28 are part of a single arched surface. The sensor housing 14 also includes an arched planar end wall 32 located at the distal end of the sensor housing 14. The end wall 32 can be selectively removed to provide access to the interior of the sensor housing 14 (i.e., the sensor chamber 24). The removability of the end wall 32 will be discussed in more detail later when

[0115] Turning to Figure 4, the curved lower side of the sensor housing 14 includes an outlet 34. Similar to the inlet 18, the outlet 34 is also occupied by a rigid mesh 35, which provides a series of outlet openings 36 that allow liquid to flow out of the sensor housing back into the porous medium. The area of the outlet 34 is smaller than the area of the inlet 18, thereby partially restricting the flow of liquid from the sensor housing back into the porous medium. Similar to the rigid mesh 20 at the inlet 18, the rigid mesh 35 at the outlet 34 is configured to prevent relatively large particles (such as rocks, stones, or clods of earth) from entering the sensor housing 14. The outlet 34 has a generally elongated configuration that substantially extends the length of the sensor housing 14.

[0116] Go to Figure 5 and Figure 6 , the sensor housing 14 is shown in the figure, where the end wall 32 has been removed and the sensor chamber 24 is exposed. The interior of the sensor housing 14 is provided with a sensor chamber 24, and the sensor device 38 is located in the sensor chamber 24. The sensor device 38 is located in the lower part 40 of the sensor chamber having a generally cylindrical profile. The sensor chamber 24 also includes an upper part 42 of the sensor chamber directly below the inlet 18. The upper part 42 of the sensor chamber has a generally rectangular profile. The upper part 42 and the lower part 40 are defined by a pair of crossbars 44 extending inwardly from opposite sides of the sensor chamber 24.

[0117] Figure 5 Illustrates the position of the sensor device 38 within the sensor chamber 24. The exact number, position, and configuration of the sensor devices may vary. In the illustrated embodiment, the sensor device 38 includes a plurality of sensors, particularly including a pH sensor 46, a dissolved metal ion sensor 48, a temperature sensor 50, a redox (oxygen reduction potential) sensor 52, a dissolved oxygen sensor 54, and a conductivity sensor 56. The sensor device also includes a solid-state reference electrode 58, such as that described in the applicant's International Patent Publication WO2018 / 201200.

[0118] The components of the sensor device 38 are arranged to facilitate the flow path of the liquid through the sensor housing 14 and promote contact between the liquid flow and the sensors. The sensors can be configured to measure the chemical or physical properties of the liquid. As Figure 5 (and Figure 7) As shown, the pH sensor 46 is generally in a planar configuration and includes a planar sensing surface 47 facing upward, which is inclined by about 30° relative to the planar inlet 18 and is inclined relative to the horizontal direction during use. The planar sensing surface 47 is recessed in the inclined surface 82 of the pH sensor. The pH sensor 46 is mounted on the inclined support 39 by resin bonding, and the inclined support occupies the volume of the sensor chamber 24 diagonally below the pH sensor 46. The support 39 is configured to occupy a part of the volume within the sensor chamber 24, thereby raising the level of condensate blocked within the chamber 24. Thus, the support 39 can facilitate the correct operation of one or more sensors (e.g., the conductivity sensor 56).

[0119] The dissolved metal ion sensor 48 includes a planar sensing surface 49 facing downward. The reference electrode 58 includes a planar sensing surface 59 facing downward. The dissolved metal ion sensor 48 and the reference electrode are spaced apart from and located above the pH sensor planar sensing surface 47 to provide an elongated gap 74 extending between the pH sensor 46 and the metal ion sensor and the reference electrode 58. The reference electrode 58 is positioned diagonally downward toward the dissolved metal ion sensor 48.

[0120] The temperature sensor 50 is configured to measure the air temperature in the sensor chamber 50 and is thus generally located above the reference electrode 58 and outside the liquid flow path. Measuring the air temperature in the sensor chamber will generally be similar to the liquid temperature within the porous medium and thus also similar to the temperature of the porous medium (e.g., the temperature of the stack). As Figure 7 As best shown, the redox sensor 52 is positioned diagonally downward toward the reference electrode 58 and generally along the diagonal axis defined by the dissolved metal ion sensor 48 and the reference electrode 58. The dissolved oxygen sensor 54 is spaced apart from the lower end of the pH sensor 46 and is located diagonally below the lower end of the pH sensor 46. The dissolved oxygen sensor is generally aligned with the pH sensor along a plane oriented diagonally. In particular, the dissolved oxygen sensor 54 includes an inclined surface 84 that is generally coplanar with the inclined surface 82 of the pH sensor 46. Both the pH sensor inclined surface 82 and the dissolved oxygen sensor inclined surface 84 are inclined by about 30° relative to the inlet 18 and are inclined relative to the horizontal direction during use.

[0121] The redox sensor 52 is spaced from the dissolved oxygen sensor 54 by approximately the same distance as the reference electrode 58 and the dissolved metal ion sensor 48 are spaced from the pH sensor 46. The elongated gap 74 thus continues diagonally downward along and above the pH sensor and the dissolved oxygen sensor. The conductivity sensor 56 is positioned within the base 28 of the sensor housing and is vertically above the outlet 34.

[0122] Figure 6An exploded view of the end wall 32 removed from the sensor housing 14 is illustrated. To also illustrate the inside of the outlet 34 at the base 28 of the sensor housing 14, Figure 6 the sensor device 38 is not shown in Figure 6 .

[0123] As Figure 6 shown, the sensor device 10 further includes a guiding device 60 extending from the inward-facing side 62 of the removable end wall 32. The guiding device 60 is configured to be inserted into the upper part 42 of the sensor chamber when the end wall 32 is positioned at the open end 70 of the sensor housing 14. The end wall 32 is removably connected at the open end 70 by resin bonding. Alternatively, the end wall 32 can be removably connected by a press fit or an interference fit. The guiding device 60 can be located directly below the inlet 18 so as to receive and guide the liquid received through the inlet 18 to flow along a predetermined flow path, which will be described in more detail in conjunction with Figure 8 .

[0124] Referring to Figure 6 and Figure 7 , the guiding device 60 includes a pair of triangular protrusions 61, 63 which extend from the inward-facing side 62 of the end wall 32 and provide an upper inclined surface 64 and a lower inclined surface 66. The upper inclined surface extends downward until it terminates at a lower edge 65. The lower inclined surface extends downward until it terminates at a lower edge 67. The lower edge 65 of the upper inclined surface 64 is positioned at a higher level than the lower edge 67 of the lower inclined surface 66 such that the liquid flow from the upper inclined surface 64 will fall onto the lower inclined surface 66 during use, and in particular will fall near the lower edge 67 of the lower inclined surface 66.

[0125] According to the configuration of this particular embodiment, the liquid captured across the length of the upper inclined surface 64 tends to move downward along the upper inclined surface 64 and is guided onto the lower inclined surface 66, and then is guided by the lower edge 67 of the lower inclined surface 66 towards the sensor device 38 (e.g., onto the sensor device 38). In particular, the lower edge 67 of the lower inclined surface 66 is configured to guide the fluid captured by the fluid guiding device to the upper part of the sensor device 38, and more particularly, to the upper part of the inclined portion of the sensor device 38.

[0126] Figure 7 A cross-sectional view of the sensor housing 14 is provided, in which the sensor device 38 and the guiding device 60 are in their respective positions within the sensor chamber 24. The sensor housing 14 is shown located within a porous medium 72, such as a heap of ore in an industrial heap leaching process.

[0127] As shown in the figure, the upper inclined surface 64 and the lower inclined surface 66 collectively extend across the entire width of the inlet 18. The second-stage filter 86 is located between the inlet 18 and the inclined surfaces 64, 66. Thus, the second-stage filter 86 is located directly below the first-stage filter including the rigid mesh 20. The second-stage filter 86 may have a spongy structure that allows elastic deformation, whereby the filter material 86 can be compressed between the inlet 18 and the inclined surfaces 64, 66, thereby substantially occupying the volume of the upper portion 42 of the sensor chamber above the inclined surfaces 64, 66.

[0128] The second-stage filter 86 is positioned to receive the liquid that has passed through the rigid mesh 20 at the inlet 18, which acts as a first-stage filter to prevent relatively large particles from entering. The second-stage filter 86 can be used to capture medium-sized particles and remove them from the liquid flow leaving the second-stage filter 86, which is collected by the inclined surfaces 64, 66 of the guiding device 60. In this way, the flow formed or collected at the guiding device 60 has been filtered through the first-stage and second-stage filters 20, 86, thereby removing large-sized and medium-sized particles.

[0129] The lower edges 65, 67 of the inclined surfaces 64, 66 of the guiding device 60 are vertically located above the upper part of the sensor device 38, and particularly above the upper end of the wetting material 76, which, in use, defines the upstream end 78 of the wetting material 76. The guiding device 60 is thus configured to direct the liquid onto the upstream end 78 of the wetting material 76. In particular, the guiding device 60 includes an opening 68 located between the lower edges 65, 67 of the inclined surfaces 64, 66, through which the received liquid converges. The opening 68 is vertically positioned above the upstream end 78 of the wetting material 76.

[0130] The wetting material 76 includes a spongy structure that is configured to allow the liquid to diffuse while also allowing the liquid to flow from the upstream end 78 to the downstream end 80 of the wetting material 76. The wetting material 76 has a generally planar or sheet-like configuration. The wetting material 76 extends through the above-mentioned gap 74. The wetting material 76 covers the inclined surface 82 of the pH sensor 46 and the inclined surface 84 of the dissolved oxygen sensor 54. The wetting material 76 provides a flow channel for the received liquid. Thus, the wetting material 76 coincides with a part of the predetermined flow path through the sensor housing 14.

[0131] From Figure 7As can be seen, the sensor device 38 includes sensors positioned on opposite upper and lower sides of the wetting material 76, and thus on opposite upper and lower sides of the flow path. In particular, the metal ion sensor 48, the reference electrode 58, and the redox sensor 52 are positioned along the upper side of the flow path, while the pH sensor 46 and the dissolved oxygen sensor 54 are positioned along the lower side of the flow path. For a given number of sensors, this configuration allows the sensor device 38 to be contained in a smaller volume compared to alternative configurations where the sensors are positioned in rows on the same side of the flow path.

[0132] The wetting material 76 can have an elastic configuration that enables it to be partially compressed into the gap 74. The wetting material 76 contacts a plurality of components within the sensor device to maintain a wet or saturated condition for these components. Thereby, the wetting material 76 wets the surfaces of the sensors that contact the wetting material 76. In particular, the wetting material contacts and wets the pH sensor 46 and its planar sensing surface 47 (as Figure 5 shown). The wetting material 76 contacts and wets the planar sensing surface 49 of the dissolved metal ion sensor 48. The wetting material 76 contacts and wets the planar sensing surface 59 of the reference electrode 58. The wetting material also contacts and wets the inclined surface 84 of the dissolved oxygen sensor 54. In addition, the wetting material 76 contacts and wets the redox sensor 52.

[0133] The downstream end 80 (i.e., the lower end) of the wetting material 76 is generally located near the base 28 of the sensor housing 14, such that the liquid exiting from the downstream end 80 will be captured inside the base 28 and pool around the outlet 34, and subsequently the conductivity sensor 56 contacts the pooled or blocked liquid.

[0134] The components of the sensor housing 14 have been described above. Now referring to Figure 8 , which illustrates the operation of the sensor device 10, particularly the flow of liquid through the sensor housing 14 along a predetermined flow path from within the porous medium 72.

[0135] Figure 8 Illustrates a side cross-section of the sensor device 10, particularly the sensor housing 14 located within the region of the porous medium 72, through which the liquid L moves downward under the action of gravity. The liquid passes through the horizontal inlet 18 and through the rigid mesh 20 within the inlet 18, which serves as a first-stage filter to prevent relatively large particles from entering the sensor housing 14. The liquid received through the inlet 18 passes downward through a second-stage filter 86 located below (i.e., inside) the inlet 18, which serves as a second-stage filter to remove medium-sized particles captured from the liquid by the second-stage filter 86.

[0136] The received liquid passing through the second - stage filter 86 is directed by the upper inclined surface 64 and the lower inclined surface 66 of the guiding device 60 towards the lower edge 67 of the lower inclined surface 66. The received liquid is collected by the inclined surfaces 64, 66 and passes through the opening 68 between the lower edges 65, 67, and then reaches the upstream end 78 of the wetting material 76 covering the pH sensor 46. The received liquid diffuses through the wetting material 76 to moisten the surface of the sensor in contact with the wetting material 76, enabling the measurement of liquid properties. In particular, the pH sensor 46, the metal - ion sensor 48, the reference electrode 58, the redox sensor 52, and the dissolved - oxygen sensor 54 are all in contact with the wetting material 76, and thus are all positioned along the flow path of the received liquid from the upstream end 78 to the downstream end 80 of the wetting material 76.

[0137] Still referring to Figure 8 , the flow path of the received liquid exits the downstream end 80 of the wetting material 76 and forms a pool 88 inside the base 28. In the illustrated embodiment, the conductivity sensor 56 is submerged in the pool 88. It should be understood that the conductivity sensor 56 does not necessarily need to be submerged and can simply be in contact with the received liquid. It should also be understood that the liquid - level of the pool 88 at the base 28 can vary according to the flow rate of the liquid through the porous medium 72. The pool 88 is located above the outlet 34 such that the liquid flows from the pool 88 through the outlet 34 to flow out of the sensor chamber 24 and back to the porous medium 72.

[0138] The size of the outlet 34 (especially its size relative to the inlet 18) can be selected based on the intended application and / or the expected liquid flow rate through the porous medium 72. The size of the outlet 34 can be selected to provide a desired restriction on the outflow rate, thereby providing or maintaining a desired liquid - level in the pool 88 within the base 28. For example, in applications where the expected liquid flow rate through the porous medium is relatively low, the outlet 34 may be configured with a smaller size than in the illustrated embodiment. Similarly, for use in a porous medium with a higher expected liquid flow rate, the outlet 34 can be provided with a larger area to increase the outflow rate.

[0139] In a particular application, the outflow rate may initially be less than the inflow rate, but as the liquid accumulates or is blocked at the base of the sensor housing, the outflow rate may increase. The inlet flow rate may vary over time, depending on the irrigation pattern applied to the top of the ore pile and may also affect the liquid flow through the medium due to the decomposition of the ore over time.

[0140] In a particular embodiment (not shown), the outlet can be configured with a variable aperture to allow adjustment of the outlet size and to allow the device to be selectively configured for the expected liquid flow rate of a particular application.

[0141] Turning to Figure 9, shows the device 10 being used with a column leaching device 11, which column leaching device 11 includes a column 12 previously shown in Figure 1 and Figure 2 . The interior of the column 12 is occupied by a porous medium 90. The column leaching device includes a gas supply pipe 92 for injecting a gas such as air, O 2 , CO 2 or N 2 into the base of the column 12 to assist the leaching kinetics.

[0142] Liquid L is poured onto the top of the porous medium and flows downward through the column 12 under the action of gravity. A sensor housing 14 is located within the porous medium 90 and is positioned to receive a sample of the liquid L through an inlet 18 horizontally oriented within the porous medium 90. The sampled liquid flows through the sensor housing 14 along a predetermined flow path discussed previously so that a sensor device ( Figure 9 , not visible in the figure) can obtain data representative of the liquid L.

[0143] As described with reference to Figure 2 , a portion 13 of the sensor device 11 remains outside the column 12 and includes an electrical component housing 15 that contains one or more PCBs configured to receive electrical signals from the sensor and / or transmit sensor data to a connected receiving hub via a wired or wireless connection. The sensor chamber within the sensor housing 12 is fluidically isolated from the electrical components within the electrical component chamber 15.

[0144] Figure 10 Illustrated are multiple sensor devices 10 distributed in various regions of a bulk ore heap 94 during an industrial heap leaching process. The multiple sensor devices 10 are immersed within the bulk ore heap 94. The multiple sensor devices 10 can be connected to each other and / or to a receiving hub via a data link cable, which receiving hub is configured to receive data obtained regarding the liquid sampled by each sensor device. Alternatively, the multiple sensor devices can be configured for wireless connection to a suitable receiving hub. Thus, the multiple sensor devices 10 can be used to obtain in-situ data regarding different parts of the bulk ore heap 94, e.g., data regarding different depths of the bulk ore heap 94. Data in a two-dimensional or three-dimensional spatial arrangement can be collected in the manner described in the applicant's earlier international patent publication WO2018 / 068087.

[0145] Those skilled in the art will recognize that the invention described herein can be subject to other variations and modifications in addition to those specifically described. It is to be understood that the invention includes all such variations and modifications that fall within the spirit and scope of the invention.

[0146] When any or all of the terms "comprise" or "include" are used in this specification (including the claims), they shall be interpreted as specifying the presence of the stated feature, integer, step or component, but not precluding the presence of one or more other features, integers, steps or components.

[0147] When the terms "comprise" and "include" are used in the specification (including the claims), they shall be interpreted as specifying the stated feature, integer, step or component, but not precluding the presence of one or more other features, integers, steps or components or groups thereof.

Claims

1. A sensor device that can be positioned within a region of a porous medium for obtaining data from a liquid within the porous medium, the device comprises: · A sensor housing that includes an inlet for receiving liquid from the porous medium into the sensor housing and an outlet for allowing the received liquid to flow out of the sensor housing, the device being configured to cause the received liquid to flow through the sensor housing along a predetermined flow path between the inlet and the outlet; · A sensor device within the sensor housing for obtaining data from the liquid flow between the inlet and the outlet, the sensor device including one or more sensors positioned along the flow path to contact the liquid and configured to measure one or more properties of the liquid to obtain data representative of the liquid at the region of the porous medium; and · A filtering device configured to remove particles from the liquid before the liquid contacts the one or more sensors.

2. The device according to claim 1, wherein the device is configured to be positioned within a region of a partially saturated porous medium and to create local saturation conditions for at least one sensor of the sensor device to facilitate data collection by the sensor device.

3. The device according to any one of the preceding claims, wherein the flow between the inlet and the outlet is configured as gravity feed, wherein the inlet is located at a higher level than the outlet, and the sensor device is located at a level lower than the inlet and higher than the outlet.

4. The device according to any one of the preceding claims, the device includes a guiding device configured to direct the liquid received through the inlet towards the sensor device.

5. The device according to claim 4, the guiding device is located between the inlet and the sensor device and is configured to converge the liquid collected from the inlet towards the sensor device.

6. The device according to claim 4 or 5, the guiding device includes at least one inclined surface that extends below the inlet and terminates at a lower edge oriented towards the sensor device, wherein in use, the liquid flow is collected or formed on the inclined surface and flows towards the lower edge and from the lower edge towards the sensor device.

7. The device according to claim 6, the guiding device includes a pair of inclined surfaces.

8. The device according to any one of claims 4 to 7, the guiding device is removable from the sensor housing.

9. The device according to any one of claims 4 to 7, the guiding device is integrated with the sensor housing.

10. The device according to any one of the preceding claims, the device comprising a wetting material in contact with the one or more sensors of the sensor device, the wetting material being positioned within the flow path and configured to maintain a wet or saturated condition at the one or more sensors to facilitate measurement by the one or more sensors of one or more properties of the liquid.

11. The device according to claim 10, the sensor device comprising a plurality of sensors in contact with the wetting material, wherein, at least one sensor contacts a first side of the wetting material and at least one sensor contacts a second, opposite side of the wetting material.

12. The device according to claim 10 or 11, wherein, the wetting material is further configured as part of the filtration device to remove particles from the received liquid.

13. The device according to claim 12, wherein, the wetting material is configured to remove relatively fine particles having a size in the range of <1 micron to 100 microns from the received liquid.

14. The device according to any one of claims 10 to 13, wherein, the flow of the liquid through the wetting material comprises capillary flow.

15. The device according to any one of the preceding claims, the sensor device comprising a plurality of sensors positioned along the flow path, wherein, at least one sensor is positioned along the lower side of the flow path and at least one sensor is positioned along the upper side of the flow path.

16. The device according to claim 15, the sensor device comprising a pH sensor configured to measure the pH value of the received liquid, the pH sensor being positioned along the lower side of the flow path.

17. The device according to claim 16, the pH sensor comprising a sensing surface having an inclined orientation configured to cause the liquid flow to move above the sensing surface.

18. The device according to claim 17, the sensor device comprising one or more additional sensors spaced apart from the sensing surface of the pH sensor by a gap, wherein, the flow path extends through the gap between the sensing surface and the one or more additional sensors.

19. The sensing surface of the pH sensor according to claim 17 or 18 is planar.

20. The sensing surface of the pH sensor according to claim 17 or 18 is non-planar.

21. The sensing surface of the pH sensor according to claim 20 is curved.

22. The device according to any one of the preceding claims, the sensor device comprising a solid-state reference electrode, wherein, one or more sensors of the sensor device are associated with the solid-state reference electrode.

23. The device according to any one of the preceding claims, the sensor device comprising at least one sensor that does not contact the liquid.

24. The device according to any one of the preceding claims, wherein, The filtration device includes a first-stage filter, which is located at the inlet and configured to prevent relatively large particles from entering through the porous medium.

25. The device according to claim 24, wherein, the first-stage filter includes a rigid mesh located at the inlet, and the rigid mesh includes openings sized to prevent particles with a width or diameter greater than about 2 mm from entering.

26. The device according to claim 24 or 25, wherein the filtration device includes a second-stage filter configured to filter the material that has passed through the first-stage filter and remove particles with a smaller size than the first-stage filter.

27. The device according to claim 26, wherein the second-stage filter is located below the first-stage filter.

28. The device according to claim 26 or 27, wherein the second-stage filter includes a sponge or sponge-like filtering material.

29. The device according to any one of claims 24 to 28, wherein the second-stage filter is configured to remove particles with a size in the range of 2 mm to 10 microns.

30. The device according to any one of claims 24 to 29, wherein the filtration device includes a third-stage filter for filtering the liquid that has passed through the second-stage filter and removing particles with a smaller size than the second-stage filter.

31. The device according to claim 30, wherein the third-stage filter is configured to remove particles with a size in the range of <1 micron to 100 microns.

32. The device according to any one of claims 30 or 31, wherein the second-stage filter and / or the third-stage filter has an anti-fouling property to reduce or resist biofouling at the sensor device.

33. The device according to any one of claims 30 to 32 when dependent on one of claims 10 to 14, wherein, the third-stage filter is provided by the wetting material.

34. The device according to any one of the preceding claims, wherein, the inlet extends along most of the upper side of the sensor housing, and wherein, in use, the inlet faces upward.

35. The device according to any one of the preceding claims, wherein, the outlet is configured to facilitate the accumulation of a relatively small volume of liquid at the outlet.

36. The device according to claim 35, wherein, the outlet is configured with an area smaller than the inlet to delay the outflow of fluid from the sensor housing.

37. The device according to any one of the preceding claims, wherein, the sensor device includes one or more of a pH sensor, a dissolved metal ion sensor, a temperature sensor, a redox sensor, a dissolved oxygen sensor, or a conductivity sensor.

38. The device according to any one of the preceding claims, wherein, the sensor device is configured to transmit sensor data to one or more hubs via a wired connection.

39. The device according to any one of the preceding claims, wherein, the sensor device is configured to transmit sensor data to one or more hubs via a wireless connection.

40. The device according to any one of the preceding claims, wherein, the sensor housing comprises a corrosion-resistant polymer material.

41. The device according to any one of the preceding claims, wherein, the sensor housing comprises a metallic material.

42. The device according to any one of the preceding claims, wherein, the sensor housing is produced by additive manufacturing.

43. The device according to any one of the preceding claims, wherein, the filtration device comprises a multi-stage configuration for removing particles of different sizes.

44. The device according to any one of claims 30 to 33, wherein, the second-stage filter and / or the third-stage filter may comprise a positively charged sponge, or a hydrophobic sponge, or a filter material coated with specific chemical functional groups for chemically adsorbing or chelating specific particles, or a filter material coated with or loaded with specific surfactants or flocculants, or a filter material or an aid that helps or promotes the aggregation of ultrafine particles for capture, or a filter material having a specific morphology (such as a sponge particle shape), porosity, or surface area that promotes the interception, capture, or attraction of specific particles of a specific shape, size, or molecular structure.

45. A column leaching device, the column leaching device comprising a straight column having a peripheral wall, the peripheral wall comprising an opening, and the column leaching device further comprising a sensor device according to any one of the preceding claims, wherein, the sensor device extends through the opening in the peripheral wall and into the interior of the column.

46. A system for obtaining data from a liquid in a heap leaching application, the system comprising a plurality of sensor devices, the sensor devices being the sensor devices according to any one of claims 1 to 44, wherein, the sensor devices are distributed throughout regions of the heap leaching material to be analyzed, and the sensor devices are configured to obtain sensor data regarding the liquid within the region of each sensor device and transmit the sensor data to one or more hubs.

47. A method for obtaining data from a liquid within a porous medium to be analyzed, the method comprising the steps of: positioning one or more sensor devices according to any one of claims 1 to 44 within the porous medium, the one or more sensor devices being configured to periodically obtain sensor data related to the chemical or physical properties of the fluid surrounding the sensor over a predetermined time period and periodically transmit the sensor data to one or more hubs via a data link.

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