Conductivity measuring device and method based on multi-channel selective electrode array

Abstract

The invention discloses a conductivity measuring device and method based on a multi-channel selection electrode array. 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 detected object; the electrode is an annular electrode; the control system comprises a first excitation current output module and a second excitation current output module. The controller controls the k-th electrode to be connected with the first excitation current through the control ends A0-Ai, controls the (k + 1)-th electrode to be connected with the second excitation current at the same time, and obtains current conductivity data from the k-th electrode or the (k + 1)-th electrode; k is from 1 to n-1 in sequence; and (n-1) groups of conductivity data are finally obtained. The conductivity measuring device and method based on the multi-channel selective electrode array can quickly measure the conductivity of the 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 refers to the process of taking away the specified mineral powder through bubbles under the action of reagents due to the different properties of minerals to achieve the purpose of mineral processing. The thickness of the foam layer has a direct impact on the recovery rate and the grade of the concentrate. During the flotation process, the thickness of the foam layer needs to be accurately measured to control the thickness of the foam layer to be constant in the optimal range, strengthen the secondary enrichment effect, and ensure the quality of the concentrate. Therefore, in the flotation process of mining and metallurgy, the accurate detection of the thickness of the foam layer is particularly important. The thickness of the traditional flotation foam layer refers to the distance from the interface between the slurry and the foam to the overflow port of the flotation tank. Since the thickness of the foam layer corresponds to the same position as the slurry level, the foam layer thickness detection is also called the slurry level detection. Existing foam layer thickness detection methods include float detection method, pressure detection method, capacitance detection method, visual image detection method, etc. However, due to the difficulty of cleaning, large steady-state error, complex process, time-consuming and other reasons of such methods, the accuracy and reliability of the existing foam layer thickness detection are low.

[0003] As for the froth layer thickness detection control circuit in the flotation process, some larger flotation machines have been promoted and used abroad and are equipped with corresponding automatic control systems. However, there is still a lack of long-term and reliable use examples in the automatic control of slurry flotation in China, and there are no standardized products suitable for slurry froth thickness measurement and automatic control. The flotation machines used in flotation 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 link 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, which can quickly measure the conductivity of a measured object and is easy to implement.

[0006] The technical solution of the invention is as follows:

[0007] A conductivity measuring device based on a multi-channel selection 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 uniformly arranged 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 through the control terminal A0-Ai, and controls the k+1th electrode to be connected to the second excitation current, 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 groups of conductivity data.

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

[0017] The electrode is an electrode type conductivity sensor, comprising: a cylindrical substrate, a plurality of metal electrode rings and a plurality of isolation rings; the plurality of isolation rings are mounted on the cylindrical substrate and are coaxial with the cylindrical substrate; the plurality of metal electrode rings are embedded in the gaps of the isolation rings (i.e., a metal electrode ring is arranged between each two adjacent isolation rings) and are coaxial with the cylindrical substrate; each metal electrode ring has a lead wire. The cylindrical substrate 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 conductivity measuring device and method based on the multi-channel selective electrode array of the present invention measures the conductivity distribution inside the slurry by using the multi-channel selective electrode array; the method has a simple structure, is easy to implement, has high measurement accuracy, and has a fast calculation speed. The detection method is convenient for fast real-time detection and processing of signals and implementation of embedded systems, and can continuously and long-term detect the measured signal. The method can realize fast real-time detection and calculation of conductivity parameters, and provide a scientific basis for studying the thickness of slurry flotation foam and liquid level and ore dressing accuracy.

[0023] The conductivity detection method adopted by the present invention is to use the conductive properties of the slurry to determine the interface between the slurry and the foam, and to calculate the thickness of the foam layer during flotation. He Shengchun et al. proposed a conductivity probe structure in which multiple electrode spirals are evenly arranged and four common electrodes form a measurement loop, which realizes the conductivity measurement of different positions in the flotation machine, but does not define the slurry 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 slurry and corrosive substances, thereby avoiding errors caused by solid sedimentation on the electrode surface, and can define the slurry layer and the foam layer according to the measurement curve, effectively solving the problems of adapting to slurry corrosion and low accuracy in the flotation foam layer thickness measurement process (further calculating 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-conducting wire, 2-2-annular metal ring electrode monomer, 2-3-isolation ring, 2-4-process hole, 2-5-isolation ring cover, 2-6-isolation ring bottom, 2-7-flotation tank, 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, it is a schematic diagram of a multi-channel selection module of an embodiment of the present invention. There are two multiplex switch chips 1-2, and the control system 1-1 is respectively connected to the input terminal D, address terminals A0, A1, A2, and A3 of the corresponding chip. The 12 single channels of each chip are respectively connected to the annular array electrodes 2-3 in the detection module 1-3 in sequence.

[0031] Among them, the annular array electrode 2-3 in the detection module 1-3 is 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 implementation example 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. The scanning frequency in the embodiment of the present invention is 400ms

[0032] like Figure 2 , which is a schematic front view of the sensor detection device, Figure 3 It is a schematic cross-sectional view of a sensor detection device, wherein the detection module is an electrode-type conductivity sensor, comprising a wire 2-1 with an outer skin, an annular metal ring electrode monomer (also called a metal electrode ring body) 2-2, an isolation ring (also called an isolation ring body) 2-3, a process hole 2-4, an isolation ring cover 2-5, an isolation ring bottom 2-6, and a reinforcing tube 3-1; the isolation ring cover, the annular metal ring electrode monomer, the isolation ring, the process hole, and the isolation ring bottom are sequentially connected; the annular metal ring electrode monomer and the isolation ring are equidistantly and staggeredly inlaid in the sensor probe; the detection module is located in a liquid pool 2-7 composed of multiphase flows of different conductivities to realize conductivity detection, and the detection sensor is fixed by a fixed 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 by threads and connected to the connecting seat by pins. The reinforcing tube is insulated and isolated by epoxy resin glue filled through process holes, and the process holes on the outside of the parts 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 respectively located at the top and bottom of the sensor probe, 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, the height of the ring is 10mm, and 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 height of the ring is 43mm, and the isolation ring is 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, and are process holes generated during the processing of the probe electrodes, and epoxy resin is injected 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 not more than 1mm, and the whole product wire is led out through the 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 the foam layer of the mining and metallurgical 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, which has n annular 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 conductivity are obtained. According to Ohm's law and the inverse relationship between conductivity and resistivity, the relationship between the conductivity σ of the object being measured and the excitation current I, the measurement voltage U, the length l of the conductor being measured, and the cross-sectional area A of the conductor being measured is:

[0039]

[0040] like Figure 4 As shown in the figure, it is the test data of a small flotation machine. The horizontal axis is the 23-channel electrode pair, and the vertical axis is the measured voltage value. From the measured voltage curve, the measured voltage value of the AB segment, i.e. the 1st to 4th electrode group, is small and stable, which is the pulp layer. This is because the pulp contains some target minerals. Under the influence of excitation, it has stronger conductivity and has little effect on the stability of the conductivity of the part in contact with the pulp near the sensor unit. The measured voltage value of the CD segment, i.e. the 12th to 23rd electrode group, is large and stable, which is the air layer. This is because the electrode is almost open in the air layer. Due to the hardware characteristics, the measured voltage value is close to 4.038v. The conductivity between the foam layers changes significantly, which is shown in the measured voltage value of the BC segment, i.e. the 4th to 12th electrode group. As the bubbles in the foam layer gradually increase as they float up, the obstruction to the current increases, reducing the conductivity of the foam layer. The thicker the foam layer, the slower the change trend. 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, 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: It includes a control system, a multi-channel selection module and a 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 uniformly arranged 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 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 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 through the control terminal A0-Ai, and controls the k+1th electrode to be connected to the second excitation current, 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 groups 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 substrate, multiple metal electrode rings and multiple isolation rings; the multiple isolation rings are mounted on the cylindrical substrate and are coaxial with the cylindrical substrate; the multiple metal electrode rings are embedded in the gaps of the isolation rings and are coaxial with the cylindrical substrate; 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 measurement device based on a multi-channel selective electrode array as described in any one of claims 1 to 5.

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