A test device for the resistivity of a column of semi-coke granules used in ferroalloy smelting.

Abstract

This utility model discloses a testing device for the resistivity of a column of semi-coke particles used in ferroalloy smelting, relating to the field of resistivity testing technology. It includes a conductive rod, a cylinder open at both ends, and a conductive counterweight fitted with the cylinder with a clearance fit. The lower end of the cylinder is fixed in a conductive base. The cylinder is used to hold the column of semi-coke particles to be tested. Screw lifting mechanisms are provided on both sides of the conductive base. A lifting beam, cooperating with the screw, is provided on the screw of the lifting mechanism. The lifting beam is located above the cylinder. The lower end of the conductive rod passes through the lifting beam and overlaps it. The upper end of the conductive counterweight is fixed to the lower end of the conductive rod. The central axis of the conductive counterweight coincides with the central axis of the cylinder. A displacement sensor is located directly above the conductive rod. A resistance measurement module is connected between the conductive rod and the conductive base.

Description

Technical Field

[0001] This utility model relates to the field of resistivity testing technology, specifically to a device for testing the resistivity of a column of semi-coke particles used in ferroalloy smelting. Technical Background

[0002] The resistivity of carbonaceous reducing agents plays a decisive role in the resistivity of ferroalloy furnace charge. High resistivity allows for deeper and more stable electrode insertion into the charge. When the resistivity of semi-coke is low, the increased current flowing through the charge causes the electrode to rise, resulting in a shallower electrode insertion depth. The resistivity of semi-coke used in ferroalloy smelting comprises two distinct resistivities: the intrinsic resistivity of the semi-coke itself (R1) and the resistivity of the packing column formed by the varying packing density of the semi-coke within the furnace (R2). R1 ​​depends on the pore structure of the semi-coke and the dry distillation temperature; R2 depends on the particle size of the semi-coke entering the furnace and its packing pattern within the furnace. The size of the semi-coke particles affects the resistivity; the larger the particle contact area, the higher the resistivity.

[0003] Currently, there is no suitable device for measuring the resistivity of granular coke piles used in ferroalloy smelting. This is because our understanding of coke resistivity has remained limited to the realm of powder resistivity. A utility model patent with authorization announcement number CN214335069U discloses a powder resistivity testing device, comprising a base plate, columns, and a cylindrical shell. Two columns are fixed to both sides of the base plate, which has a groove on which a pad is slidably mounted. A lower electrode plate is sealed at the bottom of the cylindrical shell, which has a circular cavity inside. Fixing blocks are fixed to the columns, and a connecting plate connects the fixing blocks on the two columns. A threaded hole is formed in the middle of the connecting plate, through which a screw is connected. The screw has threads on its outer circumference and is threadedly connected to the connecting plate. The bottom end of the screw is a connector. The voltage drop parameter of the powder material within the cylindrical shell varies with the height of the powder column.

[0004] While the device is simple to operate and can perform multiple measurements, it has significant shortcomings in the measurement process. The device rotates a screw via a handwheel, which in turn pushes a pressure plug into the cylindrical housing, applying pressure to the powder material. However, the device cannot precisely determine the specific pressure applied to the powder material, nor can it achieve accurate automated measurement of the material height. Furthermore, the device is primarily designed for free-flowing powder materials, while semi-coke used in ferroalloy smelting is a highly porous granular carbonaceous material, whose pore structure has a crucial impact on resistivity. Crushing semi-coke into powder would destroy its original pore structure, thus affecting the accuracy of the measurement results. Utility Model Content

[0005] To address the problems existing in the prior art, this utility model provides a testing device for the resistivity of a column of semi-coke granules used in ferroalloy smelting, in order to solve the problems of current devices being unable to clearly know the applied pressure, unable to achieve accurate automated measurement of material height, and damaging the original pore structure of semi-coke.

[0006] This utility model is achieved through the following technical solution:

[0007] A device for testing the resistivity of a column of semi-coke particles used in ferroalloy smelting includes a conductive rod, a cylinder with open ends, and a conductive counterweight that is fitted with the cylinder with a gap.

[0008] The lower end of the material cylinder is fixed in the conductive base. The material cylinder is used to place the pile of semi-coke particles to be tested. The conductive base is provided with screw lifting mechanisms on both sides. The screw of the screw lifting mechanism is provided with a lifting beam that cooperates with the screw. The lifting beam is located above the material cylinder. The lower end of the conductive rod passes through the lifting beam and overlaps the lifting beam. The upper end of the conductive counterweight is fixed to the lower end of the conductive rod.

[0009] The central axis of the conductive counterweight coincides with the central axis of the material cylinder. A displacement sensor is installed directly above the conductive rod, and a resistance measurement module is connected between the conductive rod and the conductive base.

[0010] The further improvement of this utility model is as follows:

[0011] The diameter of the conductive counterweight is 0.8 to 1.2 mm smaller than the inner diameter of the barrel.

[0012] There are two lead screws, which are symmetrically distributed along the central axis of the barrel.

[0013] The lifting beam has two circular ends, and the inner wall of the circular ends is provided with an internal thread that rotates with the external thread of the lead screw. The circular ends of the lifting beam are rotatably mounted on the corresponding lead screws.

[0014] A sleeve extends downward from the lower end of the center of the lifting beam. A frustum-shaped through hole communicating with the sleeve is provided at the center of the lifting beam. The upper end face of the through hole is larger than the lower end face, and the inner diameter of the lower end face is equal to the inner diameter of the sleeve.

[0015] The conductive rod includes a rod head and a rod column with an integral structure. The main structure of the rod head is cylindrical. A frustum section extends downward from the lower end of the rod head. The upper end face of the frustum section is larger than the lower end face. The upper end face is the same as the outer diameter of the lower end of the rod head, and the lower end face is the same as the outer diameter of the rod column. The frustum section is inserted into a through hole. The diameter of the rod column is smaller than the inner diameter of the sleeve, and the length of the rod column is greater than the length of the sleeve.

[0016] After the boom column passes through the through hole and the sleeve in sequence, the frustum section at the lower end of the boom head is inserted into the through hole. The boom head is located on the upper surface of the lifting beam, and the upper end of the conductive counterweight is fixed to the end of the boom column.

[0017] The outer wall of the lower end of the material cylinder is provided with an external thread, and the upper surface of the conductive base is provided with a groove for inserting and engaging with the material cylinder. The side wall of the groove is provided with an internal thread that rotates and engages with the external thread of the lower end of the material cylinder. The lower end of the material cylinder is fixedly connected to the groove of the conductive base by the thread.

[0018] The conductive base has a T-shaped longitudinal section, with the upper end being larger than the lower end. The lower end of the conductive base is embedded in a cylindrical conductive limiting groove, the outer wall of which is flush with the material cylinder. The conductive base is connected to the resistance measurement module through the conductive limiting groove.

[0019] The conductive limiting groove is fixed on a cylindrical insulating platform, which is flush with the material cylinder.

[0020] It also includes an outer housing, in which the lead screw lifting mechanism and the insulated storage platform are arranged, and the displacement sensor is fixed to the top of the inner wall of the outer housing.

[0021] The resistance measurement module is fixed on the outer wall of the outer casing, higher than the material cylinder and lower than the displacement sensor.

[0022] Compared with the prior art, the present invention has the following beneficial technical effects:

[0023] This invention provides a device for measuring the resistivity of a semi-coke granule stack for ferroalloy smelting. Driven by a lead screw, a conductive counterweight gradually moves downwards before and after placing the semi-coke granule sample, contacting the bottom of the conductive limiting groove and the sample respectively. This ensures controllable and uniform contact pressure between the conductive counterweight and the semi-coke stack. A displacement sensor accurately measures the downward distance of the conductive rod, thus obtaining the stack height. The resistance measurement module monitors the resistance between the conductive rod and the conductive base in real time, accurately obtaining the resistance data of the semi-coke granule stack under different pressures, ultimately yielding the resistivity of the stack. This design, through automated control of the applied pressure, avoids the errors of traditional manual measurement. Simultaneously, it maintains the natural stacking state of the semi-coke granules, making the resistivity measurement more closely resemble actual production conditions, thus improving the reliability and applicability of the test results. The system employs replaceable counterweights, allowing for the selection of different specifications of pressure-applying counterweights based on the pressure requirements of various furnace charges (precisely controlling the pressure applied to the charge column to simulate the actual packing pressure of semi-coke particles within the furnace). This enables precise pressure control and simplifies replacement. Using conductive counterweights as contact electrodes increases the contact area between the semi-coke and the measuring electrode, resulting in more stable and effective resistance measurement. Equipped with a displacement sensor and resistance measurement module, it achieves automated measurement and resistivity determination, improving measurement efficiency and accuracy. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the main internal structure of the testing device described in this utility model;

[0025] Figure 2 This is a schematic diagram of the structure of the testing device described in this utility model when the lifting beam moves to the lower limit position.

[0026] Figure 3 This is a left view of the testing device described in this utility model.

[0027] Figure 4 This is a schematic diagram of the structure of the testing device described in this utility model when the lifting beam is in the upper limit position.

[0028] Figure 5 This is a schematic diagram of the lifting beam described in this utility model.

[0029] Figure 6 This is a schematic diagram of the conductive suspension rod described in this utility model.

[0030] In the diagram: 1. Conductive lifting rod; 2. Lifting beam; 3. Lead screw; 4. External housing; 5. Conductive counterweight; 6. Material cylinder; 7. Conductive base; 8. Conductive limiting groove; 9. Insulating storage platform; 10. Displacement sensor; 11. Wire; 12. Resistance measurement module; 13. Loading height limit mark; 21. Sleeve; 22. Through hole; 41. Handle; 42. Side door; 101. Lifting rod head; 102. Lifting rod column. Detailed Implementation

[0031] The present invention will be further described below with reference to specific embodiments. These embodiments are for illustrative purposes only and are not intended to limit the scope of the present invention. Furthermore, it should be understood that after reading the description of the present invention, those skilled in the art can make various alterations or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0032] This utility model discloses a testing device for the resistivity of a column of semi-coke granules used in ferroalloy smelting. It mainly includes a conductive rod 1, an outer housing 4, a screw lifting mechanism, a cylinder 6 with open ends, wires 11, a resistance measuring module 12, a displacement sensor 10, and a conductive counterweight 5 that is fitted with the cylinder 6 with a gap. The conductive counterweight 5 is made of high-density conductive materials such as brass and has both pressure and conductivity functions. The cylinder 6 is made of alumina.

[0033] like Figure 1 and Figure 4 As shown, the lower end of the feed cylinder 6 is fixed in the conductive base 7. A column of semi-coke particles to be tested is placed in the feed cylinder 6. The conductive base 7 has screw-driven lifting mechanisms on both sides. A lifting beam 2, which rotates and engages with the screw 3, is mounted on the screw 3. The lifting beam 2 is located above the feed cylinder 6. The lower end of the conductive rod 1 passes through the lifting beam 2 and overlaps its upper surface. The upper end of the conductive counterweight 5 is fixed to the lower end of the conductive rod 1. The conductive counterweight 5 coincides with the central axis of the feed cylinder 6. A displacement sensor 10 is located directly above the conductive rod 1. A resistance measurement module 12 is electrically connected between the conductive rod 1 and the conductive base 7. The screw-driven lifting mechanism precisely controls the pressure of the conductive counterweight 5 on the semi-coke particle column, ensuring consistent measurement conditions. A closed circuit is formed by the conductive rod 1 and the conductive base 7, and the resistance value of the column is measured by the resistance measurement module 12. This embodiment achieves accurate measurement of the resistivity of the semi-coke particle column, providing data support for optimizing the ferroalloy smelting process. In other embodiments, the material and shape of the counterweight can be adjusted to accommodate different types of particulate materials.

[0034] Specifically, there are two lead screws 3, symmetrically distributed along the central axis of the feed cylinder 6. This double-lead screw design ensures the smoothness and symmetry of the movement of the lifting beam 2. The synchronous rotation of the symmetrically distributed lead screws 3 achieves uniform pressure application above the feed cylinder 6. This embodiment ensures uniform pressure on the stacked column of semi-coke particles, improving the accuracy of resistivity measurements.

[0035] In a preferred embodiment, the two ends of the lifting beam 2 are designed as annular rings, with internal threads on the inner wall of the rings that rotatably engage with the external threads of the lead screw 3. Therefore, the annular rings at both ends of the lifting beam 2 are rotatably mounted on the corresponding lead screws 3. The annular design ensures the stability and smooth rotation of the lifting beam 2 on the lead screw 3. Through the engagement of the internal and external threads, precise control of the up-and-down movement of the lifting beam 2 along the lead screw 3 is achieved. This embodiment ensures that the conductive counterweight 5 can smoothly apply pressure to the semi-coke granule accumulation column, avoiding vibration interference during the measurement process.

[0036] Furthermore, such as Figure 5 and Figure 6 As shown, a sleeve 21 extends downward from the lower end of the center of the lifting beam 2. A frustum-shaped through hole 22 communicating with the sleeve 21 is provided at the center of the lifting beam 2. The upper end face of the through hole 22 is larger than the lower end face, and the inner diameter of the lower end face is equal to the inner diameter of the sleeve 21. The conductive rod 1 includes a rod head 101 and a rod column 102, which are integral structures. The main structure of the rod head 101 is cylindrical. A frustum-shaped section extends downward from the lower end of the rod head 101. The upper end face of the frustum-shaped section is larger than the lower end face, and the upper end face is the same as the outer diameter of the lower end of the rod head 101. The lower end face is equal to the outer diameter of the rod column 102. The outer diameters of the two sections are the same, and the frustum section is inserted into the through hole 22. The diameter of the lifting rod 102 is smaller than the inner diameter of the sleeve 21, and the length of the lifting rod 102 is greater than the length of the sleeve 21. After the lifting rod 102 passes through the through hole 22 and the sleeve 21 in sequence, the frustum section at the lower end of the lifting rod head 101 is inserted into the through hole 22. The lifting rod head 101 is located on the upper surface of the lifting beam 2 and is suspended on the lifting beam 2. The upper end of the conductive counterweight 5 has an internally threaded circular hole at its center, and the end of the lifting rod 102 has an external thread. The upper end of the conductive counterweight 5 is fixed to the end of the lifting rod 102 by the thread. This structural design ensures a stable connection between the conductive lifting rod 1 and the lifting beam 2, while allowing the lifting beam 2 to move vertically on the conductive lifting rod 1. This allows the conductive counterweight 5 to stop moving after contacting the semi-coke particles, while allowing the lifting beam 2 to move to the lower limit position. The conductive counterweight 5 can be replaced with counterweights of different masses as needed for testing. Specifically, the height of the counterweight is calculated according to the required pressure using the formula obtained by existing methods.

[0037]

[0038] In the formula:

[0039] H—Height of the counterweight, mm;

[0040] P 目标 —Target pressure, Pa;

[0041] P0 — The pressure exerted by the weight of the boom on the material column, in Pa;

[0042] ρ — density of the counterweight, kg / m³ 3 ;

[0043] g — acceleration due to gravity, m / s² 2 .

[0044] The derivation process (4 basic formulas) is as follows:

[0045] (1. Pressure calculation); F = mg (2. Pressure calculation);

[0046] (3. Density calculation); V = SH (4. Volume calculation);

[0047] therefore,

[0048] Unit conversion from m to mm

[0049] Since the weight of the conductive rod 1 is known, the pressure it exerts on the material column is P0, and the pressure exerted by the counterweight on the material column is P = P 目标 -P0, therefore, the height of the counterweight.

[0050] In this invention, the diameter of the conductive counterweight 5 is 0.8–1.2 mm smaller than the inner diameter of the cylinder 6. This design ensures that the conductive counterweight 5 can fall freely within the cylinder 6 while maintaining good contact with the particle column, avoiding measurement errors caused by poor contact. By controlling the gap between the counterweight 5 and the inner wall of the cylinder 6, the uniformity of pressure transmission is ensured, improving measurement accuracy. This embodiment effectively reduces interference factors during the measurement process and improves the stability of resistivity measurement. In other embodiments, the gap between the diameter of the conductive counterweight 5 and the inner diameter of the cylinder 6 can be adjusted within this range to accommodate semi-coke particles of different sizes.

[0051] Specifically, this invention features an external thread on the outer wall of the lower end of the material cylinder 6, and a groove on the upper surface of the conductive base 7 for insertion and engagement with the material cylinder 6. The side wall of this groove has an internal thread that rotatably engages with the external thread on the outer wall of the lower end of the material cylinder 6. The lower end of the material cylinder 6 is fixed in the groove of the conductive base 7 via the thread. This threaded connection ensures a tight fixation between the material cylinder 6 and the conductive base 7, preventing loosening during measurement. The inner wall of the material cylinder 6 has a loading height limit mark 13, specifically upper and lower height limit marks. After the semi-coke particles to be tested are placed and form an accumulated column, they can be directly electrically connected to the conductive base 7. The material cylinder 6 will not shift under pressure, improving the accuracy of resistivity measurement. In other embodiments, the number and depth of the threads can be increased to enhance the connection strength and solve the problem of minor displacement of the material cylinder 6 during measurement.

[0052] To ensure a good electrical connection between the semi-coke particles in the feed cylinder 6 and the resistance measurement module 12, and to improve the stability of resistivity measurement, this invention designs the longitudinal section of the conductive base 7 as T-shaped, with its upper end larger than its lower end. The lower end of the conductive base 7 is embedded in the conductive limiting groove 8, which is cylindrical and made of copper, along with the conductive base 7. The outer wall of the conductive limiting groove 8 is flush with the feed cylinder 6, allowing the conductive base 7 to be electrically connected to the resistance measurement module 12 through the conductive limiting groove 8. The T-shaped cross-section design ensures the stable positioning of the conductive base 7 in the conductive limiting groove 8 while providing sufficient contact area. The contact between the conductive limiting groove 8 and the conductive base 7 forms a closed electrical measurement circuit. In other embodiments, the contact method between the conductive base 7 and the conductive limiting groove 8 can be improved, for example, by adding contact pieces, to enhance the reliability and conductivity of the electrical connection and solve potential contact problems during measurement.

[0053] To ensure electrical isolation between the conductive limiting groove 8 and the external environment and avoid external interference, this invention fixes the conductive limiting groove 8 onto a cylindrical insulating platform 9, which is flush with the material cylinder 6. The insulating platform 9 provides support, achieving the positioning and stability of the conductive limiting groove 8. This embodiment ensures the safety and accuracy of the electrical system during measurement. In other embodiments, insulating platforms 9 made of different materials can be selected to adapt to different working environments and temperature conditions, addressing the potential problem of decreased insulation performance during measurement.

[0054] This utility model's device for testing the resistivity of a semi-coke granule stack for ferroalloy smelting also includes an outer housing 4. The lead screw lifting mechanism and the insulating platform 9 are arranged on the lower surface of the outer housing 4. The displacement sensor 10 is fixed to the top of the inner wall of the outer housing 4, and the two lead screws 3 of the lead screw lifting mechanism are fixed to the lower surface of the outer housing 4. The outer housing 4 provides structural support and protection for the entire testing device, ensuring the stable operation of all components. The fixed position of the displacement sensor 10 ensures that it can accurately measure the descent distance of the conductive counterweight 5, facilitating the determination of the height of the semi-coke granule stack.

[0055] Specifically, the resistance measurement module 12 can be a high-precision ohmmeter, fixed to the outer wall of the outer housing 4. It needs to be positioned higher than the material cylinder 6 and lower than the displacement sensor 10. The wires 11 at both ends of the resistance measurement module 12 are connected to the upper surface of the suspension rod 1 and the side wall of the conductive limiting groove 8, respectively. The positional design of the resistance measurement module 12 ensures easy electrical connection with the conductive suspension rod 1 and the conductive base 7, while also facilitating maintenance and operation. The fixed position of the resistance measurement module 12 enables continuous monitoring of the resistivity of the semi-coke granule stack. This embodiment ensures the real-time performance and convenience of resistance measurement, improving the overall performance of the testing device.

[0056] As a specific example, the outer casing 4 has a length of 280mm, a height of 400mm, and a width of 60mm. The diameter of the boom head 101 is 15mm. The distance between the conductive counterweight 5 and the sleeve 21 on the boom column 102 is 150mm. The diameter of the conductive counterweight 5 is 99mm. The inner diameter of the cylinder 6 is 100mm, the wall thickness of the cylinder 6 is 15mm, and the height is 130mm. The thickness of the lower end of the conductive base 7 is 30mm, and the outer diameter of the conductive limiting groove 8 is 130mm. Figure 3 As shown, a side door 42 is provided on the left side, with a height of 170mm and a width of 140mm, to facilitate the transfer of the aforementioned components. The side door 42 is equipped with a handle 41 for easy operation.

[0057] The resistivity testing device for semi-coke granular stockpiles used in ferroalloy smelting of this application operates according to the following steps:

[0058] (1) With a target pressure of 4MPa, the height H of the counterweight is calculated to be 46.8mm using the above formula, and it is suspended on the conductive rod 1.

[0059] (2) Thoroughly clean the inside of the material cylinder 6 using a long-handled short-bristled brush. Place the cleaned material cylinder on the conductive limiting groove 8. Start the screw lifting mechanism. Driven by the screw 3, the conductive counterweight 5 gradually moves down to contact the bottom of the conductive limiting groove 8. The displacement sensor 10 records the downward movement distance of the conductive counterweight 5. The conductive rod 1 and the conductive base 7 form a closed circuit, allowing current to flow. The screw 3 continues to move to the lower limit position. When the current is flowing, the resistance measurement module 12 measures the resistance value. After stabilization, the resistance value (Ri) is recorded on the main unit. Start the screw lifting mechanism again, and the lifting beam 2 moves to the upper limit position again. Start the screw lifting mechanism again and repeat the above operation 4 times. Measure the average resistance (R). I ).

[0060] (3) Use a long-handled short-bristled brush to thoroughly clean the inside of the material cylinder 6. Weigh the semi-coke sample and place it in the material cylinder 6. Vibrate the material cylinder for 5 minutes using a standard vibrating screen machine, and then place the material cylinder on the conductive limiting groove 8.

[0061] (4) Start the screw lifting mechanism. Driven by the screw 3, the lifting beam 2 moves downward, and the conductive counterweight 5 gradually moves down to contact the sample, applying pressure to the semi-coke particle accumulation column. The displacement sensor 10 records the downward distance of the conductive counterweight 5. The conductive rod 1 and the conductive base 7 form a closed circuit, and the lifting beam 2 continues to move until it reaches the lower limit position. Figure 2 As shown. When the current is turned on, the resistance measurement module 12 measures the resistance value, and after it stabilizes, records the resistance value (R) on the host. N The main unit first calculates the material column stacking height (L). N Then the resistivity value (ρ) is calculated. N Start the screw lifting mechanism, and the lifting beam 2 moves back to the upper limit position. Start the screw lifting mechanism again, and repeat the above operation 4 times. Take the average resistivity of the 5 measurements as the resistivity value (ρ) of the stock column in this experiment. C ),

[0062]

[0063] (5) Repeat steps (3) and (4) twice, and measure ρ using the three repeated experiments. C The average value is used as the resistivity (ρ) of the semi-coke stockpile. a The specific results are shown in Table 1.

[0064]

[0065] Throughout the process, different smelting conditions can be simulated, enabling precise measurement of the resistivity of the semi-coke particle stack. This provides important data support for optimizing ferroalloy smelting processes, thereby allowing for a more comprehensive evaluation of the performance of semi-coke particles and laying the foundation for improving the quality and production efficiency of ferroalloy products.

[0066] Table 1 summarizes the relevant data above.

[0067]

Claims

1. A device for testing the electrical resistivity of a column of packed particles of green coal for ferroalloy smelting, characterised in that, It includes a conductive rod (1), a material cylinder (6) with open ends, and a conductive counterweight (5) that is fitted with the material cylinder (6) with a clearance. The lower end of the material cylinder (6) is fixed in the conductive base (7). The material cylinder (6) is used to place the pile of semi-coke particles to be tested. The conductive base (7) is provided with a screw lifting mechanism on both sides. The screw (3) of the screw lifting mechanism is provided with a lifting beam (2) that cooperates with the screw (3). The lifting beam (2) is located above the material cylinder (6). The lower end of the conductive rod (1) passes through the lifting beam (2) and overlaps on the lifting beam (2). The upper end of the conductive counterweight (5) is fixed to the lower end of the conductive rod (1). The central axis of the conductive counterweight (5) coincides with the central axis of the cylinder (6). A displacement sensor (10) is installed directly above the conductive rod (1). A resistance measurement module (12) is connected between the conductive rod (1) and the conductive base (7).

2. The apparatus for testing the electrical resistivity of a packed column of green coal particles for ferroalloy smelting according to claim 1, characterized in that, The diameter of the conductive counterweight (5) is 0.8 to 1.2 mm smaller than the inner diameter of the barrel (6).

3. The apparatus for testing the electrical resistivity of a packed column of green coal particles for ferroalloy smelting according to claim 1, characterized in that, There are two lead screws (3), which are symmetrically distributed along the central axis of the barrel (6).

4. The apparatus for testing the electrical resistivity of a packed column of green coal particles for ferroalloy smelting according to claim 3, characterized in that, The lifting beam (2) has two circular rings at both ends. The inner wall of the rings is provided with an internal thread that rotates with the external thread of the lead screw (3). The circular rings at both ends of the lifting beam (2) are rotatably mounted on the corresponding lead screw (3).

5. The apparatus for testing the resistivity of a column of semi-coke granules used in ferroalloy smelting according to claim 4, characterized in that, A sleeve (21) extends downward from the lower end of the center of the lifting beam (2). A frustum-shaped through hole (22) communicating with the sleeve (21) is provided at the center of the lifting beam (2). The upper end face of the through hole (22) is larger than the lower end face, and the inner diameter of the lower end face is equal to the inner diameter of the sleeve (21). The conductive rod (1) includes a rod head (101) and a rod column (102) with an integral structure. The main structure of the rod head (101) is a cylinder. The lower end of the rod head (101) extends downward to provide a frustum section. The upper end face of the frustum section is larger than the lower end face, and the upper end face is the same as the outer diameter of the lower end of the rod head (101). The lower end face is the same as the outer diameter of the rod column (102). The frustum section is inserted into the through hole (22). The diameter of the rod column (102) is smaller than the inner diameter of the sleeve (21), and the length of the rod column (102) is greater than the length of the sleeve (21). After the boom column (102) passes through the through hole (22) and the sleeve (21) in sequence, the frustum section at the lower end of the boom head (101) is inserted into the through hole (22). The boom head (101) is located on the upper surface of the lifting beam (2), and the upper end of the conductive counterweight (5) is fixed to the end of the boom column (102).

6. The apparatus for testing the electrical resistivity of a packed column of green coal particles for ferroalloy smelting according to claim 1, characterized in that, The lower end of the material cylinder (6) is provided with an external thread on its outer wall. The upper surface of the conductive base (7) is provided with a groove that is inserted and engaged with the material cylinder (6). The side wall of the groove is provided with an internal thread that is rotatably engaged with the external thread of the lower end of the material cylinder (6). The lower end of the material cylinder (6) is fixedly connected to the groove of the conductive base (7) by the thread.

7. The apparatus for testing the electrical resistivity of a packed column of green coal particles for ferroalloy smelting according to claim 6, characterised in that, The conductive base (7) has a T-shaped longitudinal section with the upper end being larger than the lower end. The lower end of the conductive base (7) is embedded in a cylindrical conductive limiting groove (8). The outer wall of the conductive limiting groove (8) is flush with the material cylinder (6). The conductive base (7) is connected to the resistance measurement module (12) through the conductive limiting groove (8).

8. The apparatus for testing the electrical resistivity of a packed column of green coal particles for ferroalloy smelting according to claim 7, characterized in that, The conductive limiting groove (8) is fixed on the cylindrical insulating platform (9), which is flush with the material cylinder (6).

9. The apparatus for testing the electrical resistivity of a packed column of green coal particles for ferroalloy smelting according to claim 8, characterized in that, It also includes an outer housing (4), in which the screw lifting mechanism and the insulating storage platform (9) are arranged, and the displacement sensor (10) is fixed to the top of the inner wall of the outer housing (4).

10. The apparatus for testing the electrical resistivity of a packed column of green coal particles for ferroalloy smelting according to claim 9, characterized in that, The resistance measurement module (12) is fixed on the outer wall of the outer box (4), and is higher than the material cylinder (6) and lower than the displacement sensor (10).

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