A conductivity measuring device and method based on a multi-channel selection electrode array

Abstract

The application discloses a conductivity measuring device and method based on a multi-channel selection electrode array, and relates to the technical field of conductivity measurement. The conductivity measuring device comprises a control system, a multi-channel selection module and a detection module. The multi-channel selection module adopts two multiplexing chips. The detection module comprises n uniformly arranged electrodes arranged in a measured object. The electrodes are ring electrodes. The control system comprises a first excitation current output module and a second excitation current output module. A controller controls the kth electrode to be connected with the first excitation current and the k+1th electrode to be connected with the second excitation current through a control end A0-Ai, and obtains current conductivity data from the kth electrode or the k+1th electrode. k is sequentially taken as 1 to n-1. Finally, n-1 groups of conductivity data are obtained. The conductivity measuring device and method based on the multi-channel selection electrode array can quickly measure the conductivity of a measured object and are easy to implement.

Description

Technical Field

[0001] The invention relates to a conductivity measuring device and method based on a multi-channel selective electrode array. Background Art

[0002] Flotation is the process of removing specific mineral fines through bubbles under the action of reagents, depending on the properties of the minerals, to achieve the purpose of mineral processing. The thickness of the foam layer has a direct impact on the recovery rate and concentrate grade. During the flotation process, the foam layer thickness must be accurately measured to control the foam layer thickness to remain constant within the optimal range, enhance secondary enrichment, and ensure concentrate quality. Therefore, accurate measurement of the foam layer thickness is particularly important in the flotation process of mining and metallurgy. Traditional flotation foam layer thickness refers to the distance from the interface between the slurry and foam to the overflow of the flotation cell. Because the foam layer thickness and the slurry level correspond to the same position, foam layer thickness detection is also called slurry level detection. Existing foam layer thickness detection methods include float detection, pressure detection, capacitance detection, and visual image detection. However, due to the difficulty of cleaning, large steady-state errors, complex processes, and time-consuming nature of these methods, the accuracy and reliability of existing foam layer thickness detection are relatively low.

[0003] As for the foam layer thickness detection control circuit during the flotation process, some larger flotation machines have been promoted and used abroad and are equipped with corresponding automatic control systems. However, China still lacks long-term and reliable use examples in the automatic control of slurry flotation, and there are no standardized products suitable for slurry foam thickness measurement and automatic control. The flotation machines used in many mines lack automatic control systems and still generally use inefficient manual control. This method has the problems of high labor intensity and low flotation efficiency.

[0004] To detect the thickness of the foam layer, a key step is to measure the conductivity of the object; therefore, it is necessary to design a conductivity measurement device and method based on a multi-channel selective electrode array. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a conductivity measuring device and method based on a multi-channel selective electrode array. The conductivity measuring device and method based on the multi-channel selective electrode array can quickly measure the conductivity of the object being measured and are easy to implement.

[0006] The technical solutions of the invention are as follows:

[0007] A conductivity measuring device based on a multi-channel selective electrode array, comprising a control system, a multi-channel selection module and a detection module;

[0008] The multi-channel selection module uses two multiplexing chips: a first multiplexing chip and a second multiplexing chip;

[0009] The detection module includes n evenly spaced electrodes arranged in the object to be detected; the electrodes are ring electrodes;

[0010] The control system includes a first excitation current output module and a second excitation current output module;

[0011] The first excitation current output module is connected to the input terminal D of the first multiplexing chip, and the n output terminals S1-Sn of the first multiplexing chip are respectively connected to n electrodes; the control terminals A0-Ai of the first multiplexing chip are respectively connected to the (i+1) IO ports of the controller in the control system; the relationship between i and n is: ^i≤n≤

[0012] 2^(i+1);

[0013] The second excitation current output module is connected to the input terminal D of the second multiplexing chip, and the n output terminals S1-Sn of the second multiplexing chip are respectively connected to n electrodes; the control terminals A0-Ai of the second multiplexing chip are respectively connected to the (i+1) IO ports of the controller in the control system; the relationship between i and n is: 2^i≤

[0014] n≤2^(i+1);

[0015] The controller controls the kth electrode to be connected to the first excitation current and the k+1th electrode to be connected to the second excitation current through the control terminals A0-Ai, and obtains the current conductivity data from the kth electrode or the k+1th electrode; k takes values ​​from 1 to n-1 in sequence; and finally obtains n-1 sets of conductivity data.

[0016] The object to be measured is ore pulp.

[0017] The electrode is an electrode-type conductivity sensor, comprising: a cylindrical base, a plurality of metal electrode rings, and a plurality of isolation rings; the plurality of isolation rings are mounted on the cylindrical base and are coaxial with the cylindrical base; the plurality of metal electrode rings are embedded in the gaps between the isolation rings (i.e., a metal electrode ring is provided between each two adjacent isolation rings) and are coaxial with the cylindrical base; a wire is led out from each metal electrode ring. The cylindrical base is made by pouring transparent epoxy resin glue into a reinforcing tube (3-3).

[0018] The detection module is located in a liquid pool (2-7) composed of multiphase flows with different conductivities to realize conductivity detection, and a detection sensor is fixed by a fixing bracket (2-8).

[0019] n is 12 or 16, and i is 3.

[0020] A conductivity measurement method based on a multi-channel selective electrode array uses the aforementioned conductivity measurement device based on a multi-channel selective electrode array to perform conductivity measurement.

[0021] Beneficial effects:

[0022] The present invention's conductivity measurement device and method based on a multi-channel selective electrode array measures the conductivity distribution within a slurry using a multi-channel selective electrode array. This method boasts a simple structure, ease of implementation, high measurement accuracy, and rapid computational speed. This detection method facilitates rapid, real-time signal detection and processing, as well as embedded system implementation, enabling continuous, long-term signal detection. This method enables rapid, real-time detection and calculation of conductivity parameters, providing a scientific basis for studying froth thickness, liquid level, and beneficiation accuracy in slurry flotation.

[0023] The conductivity detection method adopted by the present invention is a method for determining the interface between the ore pulp and the foam by utilizing the conductive properties of the ore pulp, and calculating the thickness of the foam layer during the flotation process. Domestic researchers such as He Shengchun proposed a conductivity probe structure in which multiple electrode spirals are evenly arranged and four common electrodes form a measurement circuit, which enables conductivity measurement at different positions in the flotation machine, but does not define the ore pulp layer and the foam layer. The present invention uses a single-probe annular electrode for measurement, which has a simple structure and improves efficiency. The annular electrode can adapt to slurries and corrosive substances, thereby avoiding errors caused by solid sedimentation on the electrode surface. The ore pulp layer and the foam layer can be defined according to the measurement curve, effectively solving the problems of adapting to ore pulp corrosion and low accuracy in the flotation foam layer thickness measurement process (further calculation of the foam layer thickness by conductivity is not within the scope of the present invention). BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of a multi-channel selection module according to an embodiment of the present invention.

[0025] Figure 2 It is a schematic front view of the sensor detection device.

[0026] Figure 3 It is a longitudinal (along the electrode axis) cross-sectional view of the sensor detection device.

[0027] Figure 4 It is a display of the test data (curve) of a small flotation machine.

[0028] In the figure: 1-1-control system, 1-2-multiplexing switch chip, 1-3-detection module, 2-1-wire, 2-2-annular metal ring electrode unit, 2-3-isolation ring, 2-4-process hole, 2-5-isolation ring cover, 2-6-isolation ring bottom, 2-7-flotation cell, 2-8-fixed bracket, 3-1-reinforcement tube. DETAILED DESCRIPTION

[0029] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments:

[0030] Example 1: Figure 1-3 ,like Figure 1 As shown, this is a schematic diagram of a multi-channel selection module according to an embodiment of the present invention. There are two multiplexing switch chips 1-2. The control system 1-1 is connected to the input terminal D, address terminals A0, A1, A2, and A3 of the corresponding chip, respectively. The 12 single channels of each chip are connected to the annular array electrodes 2-3 in the detection module 1-3 in sequence.

[0031] Among them, the annular array electrodes 2-3 in the detection module 1-3 are divided into odd-numbered annular metal ring electrode monomers and even-numbered annular metal ring electrode monomers, and the multiplex switch chip 1-2 realizes the conversion of the measuring electrode pair by changing the address bit. The specific embodiment is as follows: Assume that the multi-channel detection device for slurry level starts detection in the first detection cycle, the 12 single-channel outputs of the multiplex switch chip a are connected to the odd-numbered electrodes, and the 12 single-channel outputs of the multiplex switch chip b are connected to the even-numbered electrodes. When the first detection cycle arrives, the control system controls the two multiplex switch chips to simultaneously select electrode 1 and electrode 2 , at this time, electrode 1 and electrode 2 constitute a liquid level detection electrode pair; when the second detection cycle arrives, the control system inputs the address bit of the multiplexing switch chip a plus one, while the address bit input to the multiplexing switch chip b remains unchanged, so that electrode 2 and electrode 3 are selected and constitute a liquid level detection electrode pair; when the third detection cycle arrives, the control system inputs the address bit of the multiplexing switch chip b plus one, while the address bit input to the multiplexing switch chip a remains unchanged, thereby selecting the next pair of electrodes, and so on, until the last electrode is selected, and a measurement cycle ends. In the embodiment of the present invention, the scanning frequency is 400ms

[0032] like Figure 2 FIG. 1 is a schematic front view of a sensor detection device. Figure 3 This is a schematic cross-sectional view of a sensor detection device. The detection module is an electrode-type conductivity sensor, comprising a wire 2-1 with an outer sheath, an annular metal ring electrode unit (also known as a metal electrode ring body) 2-2, an isolation ring (also known as an isolation ring body) 2-3, a process hole 2-4, an isolation ring cover 2-5, an isolation ring base 2-6, and a reinforcement tube 3-1. The isolation ring cover, annular metal ring electrode unit, isolation ring, process hole, and isolation ring base are sequentially connected. The annular metal ring electrode unit and the isolation ring are equidistantly and staggeredly embedded in the sensor probe. The detection module is located in a liquid pool 2-7 composed of multiphase flow with different conductivities to perform conductivity detection, and the detection sensor is fixed by a fixing bracket 2-8.

[0033] The overall length of the probe electrode in this embodiment is set to 1200mm, with connecting screws, a reinforcing tube 3-1 inserted inside, the wire 2-1 passes through the reinforcing tube, and is connected to the bottom of the isolation ring with a thread and to the connecting seat with a pin. The reinforcing tube is insulated and isolated by filling epoxy resin glue through the process holes, and the process holes on the outside of the part are sealed with epoxy resin glue, and the surface is smooth, neat and not deformed.

[0034] The isolation ring cover 2-5 and the isolation ring bottom 2-6 are located at the top and bottom of the sensor probe respectively, and are made of POM plastic, black in color, with a smooth surface without burrs, an inner diameter of 50mm, an outer diameter of 60mm, and a ring height of 27mm.

[0035] The annular metal ring electrode monomers 2-2 and the isolation rings 2-3 are staggered and equidistantly inlaid on the surface of the sensor probe, wherein the number of the annular metal ring electrode monomers is 24, the material is stainless steel, the surface is smooth and burr-free, the inner diameter of the ring is 50mm, the outer diameter of the ring is 60mm, and the ring height is 10mm. Each ring electrode has a wire for signal transmission; the number of the isolation rings is 23, the material is POM plastic, the color is black, the surface is smooth and burr-free, the inner diameter of the ring is 50mm, the outer diameter of the ring is 60mm, and the ring height is 43mm. The isolation rings are connected to the upper and lower annular metal ring electrode monomers; the metal ring electrodes are grouped in pairs to form a liquid level detection electrode pair, and the control system controls the multi-channel selection module to realize the detection switching of each pair of electrodes.

[0036] The process holes 2-4 are located in the center of the 23 isolation rings, isolation cup covers, and isolation cup bottoms. They are process holes generated during the processing of the probe electrodes, and epoxy resin is poured through the process holes.

[0037] The number of wires 2-1 is 24, and the wire diameter is 0.5mm. 2 , the outer diameter is no more than 1mm, and the overall product wire is led out through an aviation plug; the detection module is located in the flotation cell 2-7 composed of fluids with different electrical conductivities to realize detection. The flotation cell contains the pulp layer and foam layer of the mining and metallurgy flotation process. Due to the action of reagents and mechanical stirring, the foam layer is located at the upper part of the flotation cell and the pulp layer is located at the lower part of the flotation layer. The probe electrode must pass through the foam layer and be placed in the pulp layer.

[0038] The sensor detection device is an electrode-type conductivity sensor with n ring electrodes. Under the control of the multi-channel selection module, an excitation current in the range of 0.1mA-20mA is applied to the flotation cell and the measured voltage values ​​of (n-1) groups of fluids with different conductivities are obtained. According to Ohm's law and the inverse relationship between conductivity and resistivity, the relationship between the conductivity σ of the measured object and the excitation current I, the measured voltage U, the length l of the measured conductor, and the cross-sectional area A of the measured conductor is as follows:

[0039]

[0040] like Figure 4 The following figure shows test data for a small flotation machine. The horizontal axis represents 23 electrode pairs, and the vertical axis represents the measured voltage. The measured voltage curve shows that the measured voltage values ​​for the 1st to 4th electrode groups (A to B) are small and stable, representing the slurry layer. This is because the slurry contains some target minerals, which, under the influence of the excitation, has stronger conductivity and less impact on the stability of the conductivity of the portion of the sensor unit in contact with the slurry. The measured voltage values ​​for the 12th to 23rd electrode groups (C to D) are large and stable, representing the air layer. This is because the electrodes are almost disconnected in the air layer. Due to hardware characteristics, the measured voltage value is close to 4.038V. The conductivity of the foam layer varies significantly, as shown by the measured voltage values ​​for the 4th to 12th electrode groups (B to C). This is because the bubbles in the foam layer gradually increase in size as they float upward, increasing their resistance to current flow and reducing the conductivity of the foam layer. The thicker the foam layer, the slower this change. Point B is the interface between the slurry layer and the foam layer, and point C is the interface between the foam layer and the air layer. Based on the above analysis, the measurement voltage result curve of the present invention can simply and intuitively define the slurry layer and the foam layer, thereby determining the position of the interface (interface) and thus determining the thickness of the foam layer; the scanning frequency is 400ms per cycle, realizing a highly efficient, highly accurate, simple and intuitive multi-channel selective electrode array conductivity measurement device and method, on this basis, the thickness of the foam layer can be further calculated or determined.

Claims

1. A conductivity measuring device based on a multi-channel selective electrode array, characterized in that: Including control system, multi-channel selection module and detection module; The multi-channel selection module uses two multiplexing chips: a first multiplexing chip and a second multiplexing chip; The detection module includes n evenly spaced electrodes arranged in the object to be detected; the electrodes are ring electrodes; The control system includes a first excitation current output module and a second excitation current output module; The first excitation current output module is connected to the input terminal D of the first multiplexing chip, and the n output terminals S1-Sn of the first multiplexing chip are respectively connected to n electrodes; the control terminals A0-Ai of the first multiplexing chip are respectively connected to the i+1 IO ports of the controller in the control system; the relationship between i and n is: 2^i≤n≤2^(i+1); The second excitation current output module is connected to the input terminal D of the second multiplexing chip, and the n output terminals S1-Sn of the second multiplexing chip are respectively connected to n electrodes; the control terminals A0-Ai of the second multiplexing chip are respectively connected to the i+1 IO ports of the controller in the control system; the relationship between i and n is: 2^i≤n≤2^(i+1); The controller controls the kth electrode to be connected to the first excitation current and the k+1th electrode to be connected to the second excitation current through the control terminals A0-Ai, and obtains the current conductivity data from the kth electrode or the k+1th electrode; k takes values ​​from 1 to n-1 in sequence; and finally obtains n-1 sets of conductivity data.

2. The conductivity measuring device based on a multi-channel selective electrode array according to claim 1, characterized in that: The object to be measured is ore pulp.

3. The conductivity measuring device based on a multi-channel selective electrode array according to claim 1, characterized in that: The electrode is an electrode-type conductivity sensor, including: a cylindrical base, multiple metal electrode rings and multiple isolation rings; the multiple isolation rings are mounted on the cylindrical base and are coaxial with the cylindrical base; the multiple metal electrode rings are embedded in the gaps of the isolation rings and are coaxial with the cylindrical base; each metal electrode ring has a lead wire.

4. The conductivity measuring device based on a multi-channel selective electrode array according to claim 1, characterized in that: The detection module is located in a liquid pool (2-7) composed of multiphase flows with different conductivities to realize conductivity detection, and a detection sensor is fixed by a fixing bracket (2-8).

5. The conductivity measuring device based on a multi-channel selective electrode array according to any one of claims 1 to 4, characterized in that: n is 12 or 16, and i is 3.

6. A conductivity measurement method based on a multi-channel selective electrode array, characterized in that: Conductivity measurement is performed using the conductivity measuring device based on the multi-channel selective electrode array described in any one of claims 1 to 5.

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