All-electric melting shaft kiln for basalt fiber production and melting wire drawing method

Abstract

The invention relates to the field of inorganic nonmetal fiber manufacturing, and discloses an all-electric melting shaft kiln for basalt fiber production and a melting wire drawing method. The vertical electric melting furnace body is sequentially provided with a melting area, a clarifying area and a wire drawing area along the height direction, each area is provided with a plurality of groups of molybdenum electrodes and is supplied with energy by a transformer and a power adjusting unit in a partitioned manner, and a thermocouple-temperature controller is matched to form closed-loop temperature control; a platinum-rhodium alloy bushing plate is arranged at the bottom of the kiln to serve as a discharging component, and the molten liquid level is detected by a probe and is linked with an automatic feeding device to be kept constant. The system realizes continuous and stable wire drawing under the condition of no fuel gas, basalt continuous fibers with the diameter of 5.5-22 microns can be prepared, the comprehensive utilization rate of raw materials is greater than or equal to 95%, and the system has the advantages of low energy consumption, high melt quality, environmental protection, remarkable reduction of waste gas emission and the like.

Description

Technical Field

[0001] This invention belongs to the field of inorganic non-metallic material production technology, specifically relating to an all-electric melting kiln and melting drawing method for basalt fiber production. Background Technology

[0002] Basalt fiber is made from natural basalt ore. After high-temperature melting, clarification, and purification, it flows out stably through a porous discharge component. During the traction and oiling process, it forms continuous monofilaments and is wound into finished products. Commonly used melting equipment in engineering practice includes: combustion-heated tank kilns / flame kilns, combined heating kilns using resistance or electrode-assisted melting, and all-electric melting furnaces.

[0003] Continuous wire drawing demands high stability in the temperature-viscosity window at the discharge point, as well as in the stability of chemical composition and redox state, control of bubbles and inclusions, and consistency of liquid level and flow rate. Traditional combustion-type tank kilns typically use side or top burners for heating, relying on radiation and natural convection for melting and clarification, and have discharge channels (such as ceramic nozzles or metal baffles) at the kiln bottom or side walls. While these solutions are equipped with temperature detection and gas / power regulation, and some even incorporate multi-point temperature measurement and power distribution, the lateral and longitudinal temperature uniformity is limited by the flame organization and kiln flow field. Combustion products also disturb the kiln atmosphere and the redox state of the melt, making it difficult to meet the production requirements of continuous wire drawing. In contrast, electro-assisted melting / full electro-melting solutions, by arranging electrodes (such as molybdenum electrodes) within the molten pool or using resistance heating components, can achieve zoned energy supply and on-demand energy distribution. Combined with liquid level linkage control and porous precious metal components to improve discharge consistency, this is beneficial for the realization of continuous wire drawing production. Furthermore, with the increasing demand for energy conservation, emission reduction, and product consistency, all-electric melting and vertical furnace bodies are gradually gaining attention in order to shorten the melt residence path, improve the longitudinal temperature field distribution, and reduce combustion emissions.

[0004] However, most fully electric vertical kilns still have thermal coupling between temperature zones, which leads to mutual influence in control and difficulty in maintaining a stable and reproducible longitudinal temperature gradient in the long term; at the same time, local uneven temperature in the discharge zone can easily cause viscosity difference and flow mismatch in the pores. Overall, existing technologies focus more on improving heating methods, adding control points and optimizing discharge materials, but are still insufficient for the coordinated control of the three stages of "melting-clarification-discharge" and the integrated control of "temperature / liquid level dual closed loop" under the vertical compact structure. The main problems include: (1) Insufficient process stability and discharge consistency: the longitudinal temperature gradient is difficult to stabilize in the long term, and thermal coupling between temperature zones and local uneven temperature in the discharge zone coexist; the lag in liquid level control causes fluctuations in static pressure head, resulting in viscosity drift, pore mismatch and wire diameter fluctuations, which can easily lead to wire breakage and pore blockage. (2) Limited melt quality and clarification: fluctuations in raw materials and redox states superimposed on temperature field disturbances reduce clarification efficiency, and bubbles and inclusions rise to the discharge zone, forming surface defects and affecting the stability of continuous wire drawing. (3) Energy efficiency and operation and maintenance pressure are relatively high: combustion type has high energy consumption and heavy emissions; some electric fluxing has high unit energy consumption due to heat preservation and structural size limitations; the life of furnace lining, electrodes and precious metal parts is constrained by high temperature and chemical environment, and maintenance is frequent and lacks modular and online replacement support.

[0005] Based on the above issues, the industry urgently needs a compact vertical electrofusion equipment that combines temperature / liquid level dual closed-loop coordinated control with a porous precious metal spinneret for temperature uniformity and insulation design. This would improve melt quality and outflow consistency from the source, achieve long-term stability of continuous wire drawing, and simultaneously take into account energy efficiency and environmental protection. Summary of the Invention

[0006] To address the problems in the background technology, this paper provides a fully electric melting furnace and melting and drawing method for basalt fiber production, solving the problems of unstable temperature field and liquid level, insufficient melt cleanliness and drawing continuity, and high energy consumption and emissions in existing technologies. The technical solution is as follows: A fully electric vertical furnace for basalt fiber production includes: a vertical furnace body, wherein a melting zone, a refining zone, and a drawing zone are sequentially arranged along the height direction within the furnace body; multiple sets of molybdenum electrodes arranged in each zone, wherein the molybdenum electrodes are connected to a power supply via transformers and power regulators to form a zoned heating system; thermocouples and temperature control units arranged in each zone to form a closed-loop control of the temperature of each zone; a liquid level probe for detecting the liquid level in the molten pool, wherein the liquid level probe is linked with an automatic feeding mechanism to maintain a preset liquid level; a temperature-controlled discharge chamber and a drawing unit connected to the drawing zone; and a precious metal porous baffle plate arranged at the bottom of the temperature-controlled discharge chamber, wherein an array of perforations is provided for the outflow of molten basalt. Preferably, the working temperatures of the melting zone, the clarifying zone, and the drawing zone are 1500–1600℃, 1400–1480℃, and 1350–1450℃, respectively, with the working temperature of the drawing zone being lower than that of the clarifying zone.

[0007] Preferably, the precious metal porous stencil is made of Pt, and the diameter of the pores on the precious metal porous stencil is 1.6–2.2 mm, and the number of pores is 800–2000.

[0008] Preferably, the target liquid level height of the molten pool is 360–400 mm.

[0009] Preferably, it also includes a waste wire recycling and remelting channel, which is used to return the waste wire generated during the wire drawing process to the furnace for remelting, so that the overall raw material utilization rate is not less than 95%.

[0010] Preferably, the temperature control unit and the power regulator constitute a zoned power programmable control to form a stable temperature gradient along the height direction.

[0011] Preferably, the temperature-controlled discharge chamber is equipped with temperature equalization and insulation components to ensure that the temperature difference between the upstream and downstream of the precious metal porous sprue is ≤10℃, thereby improving the temperature uniformity of the precious metal porous sprue area; the temperature equalization and insulation components include a first molybdenum electrode, a first thermocouple, and a water-cooling pipe.

[0012] Preferably, the multiple sets of molybdenum electrodes are arranged symmetrically in layers along the height direction, with the molybdenum electrode in the melting zone being the main power supply electrode, the molybdenum electrode in the clarifying zone being the auxiliary electrode, and the molybdenum electrode in the drawing zone being the fine-tuning electrode.

[0013] A method for melting and drawing basalt fibers includes the following steps: S1. Basalt granular raw material is added to the vertical furnace body; S2. Under the action of multiple sets of molybdenum electrodes providing energy in zones and closed-loop temperature control, the raw material is melted in the melting zone, purified in the clarification zone, and the discharge temperature is kept stable in the drawing zone, forming a temperature gradient along the height direction; S3. The liquid level in the molten pool is maintained by the liquid level probe and the automatic feeding mechanism; S4. The molten basalt is discharged through the array of perforations of the precious metal porous perforated plate at the bottom of the furnace; S5. Under the action of the temperature-controlled discharge chamber and the drawing unit, the discharged molten basalt is stretched, oiled, and wound to obtain continuous basalt fibers.

[0014] Preferably, step S3 uses a proportional-integral-derivative (PID) or equivalent control algorithm for liquid level and feeding linkage.

[0015] The beneficial effects of this invention are as follows: (1) The present invention constructs a programmable longitudinal temperature gradient by partitioned heating and closed-loop temperature control, stabilizes the melt viscosity window, and improves the stability of continuous wire drawing; (2) The present invention achieves constant liquid level control by linking the liquid level probe with the automatic feeding structure, and the precious metal porous baffle is combined with the constant liquid level to improve the consistency of outflow from each hole and narrow the fiber diameter distribution. (3) The present invention uses an all-electric melting heat source, which does not produce combustion exhaust gas, significantly reduces exhaust gas emissions, and reduces system energy consumption; (4) The modular electrode / furnace lining of the present invention facilitates online maintenance and long-term operation, and the overall raw material utilization rate is ≥95%. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the three-dimensional structure of the all-electric melting vertical kiln of the present invention; Figure 2 This is a side view of the internal structure of the vertical furnace body of the present invention; Figure 3 This is a top view of the internal structure of the vertical furnace body of the present invention; Figure 4 This is a schematic diagram of the temperature-controlled discharge chamber structure of the present invention.

[0017] The following are the labels in the diagram: 1. Vertical furnace body; 2. Thermocouple; 3. Molybdenum electrode; 4. First thermocouple; 5. First molybdenum electrode; 6. Temperature-controlled discharge chamber; 7. Water-cooled pipe; 8. Leakage hole; 9. Waste wire recycling and remelting channel; 10. Melting zone; 11. Clarification zone; 12. Wire drawing zone; 13. Feed port. Detailed Implementation

[0018] To make the present invention clearer and more understandable, the technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the given embodiments are only one of the implementation methods and do not represent all embodiments.

[0019] In this article, terms such as "inner," "outer," "upper," and "lower" are established based on the positional relationships shown in the attached drawings. Depending on the attached drawings, the corresponding positional relationships may also change. Therefore, they should not be interpreted as an absolute limitation on the scope of protection.

[0020] Example 1 Combined with appendix Figure 1 - Appendix Figure 4 A fully electric vertical furnace for basalt fiber production includes: a vertical furnace body 1, wherein a melting zone 10, a refining zone 11, and a drawing zone 12 are arranged sequentially along the height direction within the furnace body 1, and the melting zone 10, the refining zone 11, and the drawing zone 12 are specifically arranged in a stepped manner; multiple sets of molybdenum electrodes 3 arranged in each zone, the molybdenum electrodes 3 being connected to a power supply via transformers and power regulators to form a zoned power supply and power adjustable heating system; thermocouples 2 and temperature control units arranged in each zone for real-time temperature monitoring and forming a closed-loop control of the temperature in each zone, with temperature detection and closed-loop adjustment forming a stable longitudinal gradient temperature field; a liquid level probe for detecting the liquid level in the molten pool, the liquid level probe being linked with an automatic feeding mechanism to maintain a preset liquid level; a temperature-controlled discharge chamber 6 connected to the drawing zone 12 and a drawing unit; and a precious metal porous baffle plate arranged at the bottom of the temperature-controlled discharge chamber 6, on which an array of perforations 8 for the outflow of molten basalt.

[0021] Specifically, there are four sets of molybdenum electrodes 3, which are located in the melting zone 10, the clarifying zone 11, the drawing zone 12, and the temperature-controlled discharge chamber 6, respectively. The four sets of molybdenum electrodes 3 provide energy in separate zones, forming a programmable longitudinal temperature gradient.

[0022] Specifically, the automatic feeding mechanism is a vibrating feeder; the vertical furnace body 1 is covered with an insulation layer, the frame of the vertical furnace body 1 is supported by a steel structure, and the total height of the vertical furnace body 1 is 1-2m.

[0023] The wire drawing unit includes traction, oiling, and winding units. The molybdenum electrode 3 is replaceable independently, and the vertical furnace body 1 adopts a modular structure for easy maintenance. The top of the vertical furnace body 1 corresponding to the melting zone 10 is provided with a feeding port 13 for adding materials.

[0024] The precious metal porous stencil is made of Pt, and the diameter of the stencil holes 8 on the precious metal porous stencil is 1.6–2.2 mm, and the number of holes is 800–2000.

[0025] Specifically, it also includes a waste wire recycling and remelting channel 9, which is used to return the waste wire generated during the wire drawing process to the furnace body for remelting, so that the overall raw material utilization rate is not less than 95%.

[0026] Specifically, the temperature control unit and the power regulator constitute a zoned power programmable control to form a stable temperature gradient along the height direction.

[0027] Specifically, it also includes a host computer and a control cabinet. The control cabinet is connected to the host computer, transformer, liquid level probe, automatic feeding mechanism, power regulator, molybdenum electrode 3, thermocouple 2, temperature control unit, and wire drawing unit (traction, oiling, winding) to control the entire wire drawing system. The wire drawing system includes a vertical furnace body 1, host computer / control cabinet, power transformer and power regulator, automatic feeding mechanism, wire drawing unit, and waste wire recycling and remelting channel 9, forming a continuous production line.

[0028] Operation process: Cold furnace heating → Empty furnace heat preservation → Small batch raw material feeding → Temperature / liquid level dual closed loop opening (full electric melting → clarification and purification → liquid level closed loop stabilization) → Stable outflow of molten basalt → Wire drawing, oiling, winding → Waste wire recycling and remelting.

[0029] Using the above-mentioned all-electric melting vertical kiln, the discharge temperature-viscosity window can be kept stable, and basalt fibers can be continuously drawn. The production line can run continuously for more than 1500 hours.

[0030] Example 2 Based on the all-electric melting vertical kiln described in Example 1, the liquid level probe is installed at a relatively stable flow position upstream of the discharge zone, combined with the PID control of the upper computer to control the feeding duty cycle; a minimum lag time and a small step limit are set to avoid "over-adjustment-oscillation". The liquid level probe is linked with the automatic feeding mechanism, and the target liquid level height is preferably maintained at 380±5mm.

[0031] Specifically, if the liquid level deviates from the target by ±2 mm, fine-tune the feeding (step ≤3%); if it deviates by ±5 mm, initiate rapid correction (shortly increase the duty cycle and limit the change in traction speed).

[0032] Based on the above-mentioned liquid level probe regulation, the instantaneous flow difference of each hole in the sprue is significantly reduced, and the uniformity of fiber bundle linear density is improved; the short-term fluctuation of filament diameter is reduced by more than 30%, and the stability of long-cycle continuous filament drawing is significantly improved.

[0033] Example 3 A method for melting and drawing basalt fibers includes the following steps: S1. Add basalt granular raw material to vertical furnace body 1; Basalt particles with a diameter of 10–30 mm are selected and fed evenly into the upper melting zone 10 of the vertical all-electric furnace body 1 via a vibrating feeder through a feeding hopper. To suppress static pressure head fluctuations, a liquid level probe monitors the molten pool level in real time and works in conjunction with the feeder to maintain the target liquid level at 380±5 mm.

[0034] S2. Under the power supply and closed-loop temperature control of multiple molybdenum electrodes in three zones, the raw material is melted in the melting zone 10, purified in the clarification zone 11, and the discharge temperature is kept stable in the drawing zone 12, forming a temperature gradient along the height direction. The vertical furnace body 1 consists of three zones from top to bottom: melting zone 10, refining zone 11, and drawing zone 12. Four sets of molybdenum electrodes 3 are arranged for zone-based power supply. The temperatures of each zone are set to 1480±10℃, 1450±10℃, and 1400±10℃, respectively. Multi-point thermocouples 2 collect the temperatures of each zone, and the control cabinet uses a closed-loop adjustment system to regulate the output power of the power regulator, forming a stable temperature-viscosity gradient along the height direction.

[0035] S3. Maintain a constant liquid level in the molten pool through a liquid level probe and an automatic feeding mechanism; When the liquid level deviates from the set value, the host computer will adjust the feeding duty cycle in small steps according to the deviation, and limit the change of traction speed if necessary, to ensure that the liquid level of the molten pool fluctuates within ±5 mm and the static pressure head of each hole is basically consistent.

[0036] S4. The molten basalt flows out through the array of holes 8 of the precious metal porous strainer plate at the bottom of the furnace. The bottom of the vertical furnace body 1 is equipped with a Pt precious metal porous stencil with a hole diameter of 1.8 mm and a hole count of no less than 800.

[0037] S5. Under the action of temperature-controlled discharge chamber 6 and drawing unit, the outflowing molten basalt is stretched, oiled and wound to obtain continuous basalt fibers. Molten basalt flows steadily out of the drain hole 8 into the wire drawing zone 12, where it works in conjunction with the wire drawing machine of the wire drawing unit to complete the traction. After being oiled in the upper oil tank, it is wound into shape by the winding head.

[0038] Under the above conditions, continuous and stable filament drawing is achieved, and the typical diameter of the resulting continuous basalt fiber is about 11μm (based on online diameter measurement and sampling statistics). The fiber diameter distribution is narrow and the COV is small. The production line has been running continuously for more than 1500 hours, and the outflow consistency and end breakage control meet the requirements of stable industrial production.

[0039] Specifically, step S3 uses a proportional-integral-derivative (PID) or equivalent control algorithm to perform liquid level-feed linkage.

[0040] Example 4 A vertical electric melting kiln for basalt fiber melting and drawing, based on the structure of the vertical electric melting kiln in Embodiment 1, wherein the temperature control discharge chamber 6 is equipped with temperature equalization and heat preservation components to ensure that the temperature difference between the upstream and downstream of the precious metal porous sprue is ≤10℃, thereby improving the temperature uniformity of the precious metal porous sprue area; the temperature equalization and heat preservation components include a first molybdenum electrode 5, a first thermocouple 4, and a water-cooling pipe 7.

[0041] To obtain fine denier fibers, the set temperature of the drawing zone 12 was slightly increased under uniform temperature and heat preservation conditions, and the traction speed was increased simultaneously to maintain the outlet viscosity within the target window. The kiln bottom used a Pt porous perforated plate with a pore diameter of approximately 1.8 mm and a pore count of ≥800.

[0042] Process conditions: The molten pool level is 380±5 mm, the temperature difference between the upstream and downstream of the temperature-controlled discharge chamber 6 and the precious metal porous sprue is controlled within ≤10℃, and the traction speed is linearly fine-tuned according to the target wire diameter.

[0043] Based on the above process, fine denier fibers with a diameter of φ5.5–9μm can be stably obtained; the filament diameter distribution is narrowed, and the breakage rate is further reduced. If local pore flow rate attenuation occurs, the precious metal porous stencil can be thermally cleaned or quickly replaced in the "low tension heat preservation" mode, and the steady state can be restored within 30–45 minutes.

[0044] Example 5 A fully electric vertical kiln for melting and drawing basalt fibers, based on the fully electric vertical kiln structure of Example 1, shows that the electrode layers and discharge chamber are uniformly heated in the side view structure. Multiple sets of molybdenum electrodes 3 are arranged symmetrically in layers along the height direction. The molybdenum electrodes 3 in the melting zone 10 are the main power supply, the molybdenum electrodes 3 in the clarification zone 11 are auxiliary, and the molybdenum electrodes 3 in the drawing zone 12 are for fine adjustment. The temperature-controlled discharge chamber 6 is equipped with an external heat insulation cover.

[0045] While keeping the overall settings unchanged, the temperature of the drawing zone 12 is slightly adjusted by ±5 to 10℃ to eliminate the upstream and downstream temperature difference between the temperature-controlled discharge chamber 6 and the precious metal porous baffle plate; the power ratio of the molybdenum electrode 3 (example): 50 kW for the melting zone 10, 30 kW for the clarifying zone 11, and 10 kW for the drawing zone 12, and is automatically corrected according to the feeding load.

[0046] Based on the above process, the transverse temperature difference in the porous precious metal baffle area is reduced, and the outflow is more consistent; by adjusting the traction speed within the range of φ9–12μm, the breakage rate is reduced by more than 20% compared with no temperature equalization measures.

[0047] Comparative Example 1 Compared with Example 1 (vertical all-electric melting + zoned heating + double closed loop), the difference is that the vertical all-electric melting furnace is replaced with a combustion tank furnace (with a front chamber) and multiple burners are used for heating; the temperature is controlled in only two zones; the same production cycle and target wire diameter (about 11μm) are maintained, and manual timed feeding is still used (open loop).

[0048] result: D50 / COV: 11.2μm / 6.5% (Example 1: 11.0μm / 3.0%) Decapitation frequency: 9.8 times / 10 6 m (Example 1: 3.2 times / 10) 6 m); Hole plugging: 8 times / (1000 holes·24 h) (Example 1: 1 time / (1000 holes·24 h)); Energy consumption: 8.7 MWh / t (Example 1: 6.4 MWh / t); Continuous operating time: ~600 h (Example 1: >1500 h); Defect rate: 2.1% (Example 1: 0.7%).

[0049] Conclusion: Combustion heat transfer results in poor temperature field uniformity and atmosphere stability. In addition, the open-loop feeding causes liquid level fluctuations, and the consistency and continuity of the outflow are significantly inferior to the system of this invention.

[0050] Comparative Example 2 Compared with Example 3 (liquid level-feeding dual closed-loop steady flow), the difference is that, with the vertical full electrofusion and zone temperature control unchanged, the liquid level probe and PID linkage are turned off, and timed / quantitative feeding is changed to open loop.

[0051] result: D50 / COV: 11.1 μm / 5.2% (Example 3: 11.0 μm / 3.4%) Decapitation frequency: 8.1 times / 10 6m (Example 3: 4.1 times / 10) 6 m); Hole plugging: 6 times / (1000 holes·24 h) (Example 3: 2 times / (1000 holes·24 h)); Continuous operating time: ~900 h (Example 3: >1500 h); Defect rate: 1.6% (Example 3: 0.9%) Conclusion: In the absence of liquid level closed loop, the periodic fluctuation of static pressure head causes inconsistent flow rates in each hole of the multi-hole baffle, directly amplifying the fluctuations in wire diameter and wire breakage.

[0052] Comparative Example 3 The difference from Examples 2 / 4 is that: a Pt porous perforated plate (pore diameter of about 1.8 mm and number of pores ≥800) is still used, but the temperature control discharge chamber 6 temperature equalization and heat preservation components are removed.

[0053] result: Temperature difference between upstream and downstream / lateral sides of the perforated plate: ~18℃ (Example: ≤10℃); D50 / COV: 9.2 μm / 4.7% (Example: 9.0 μm / 3.1%) Hole plugging: 5 times / (1000 holes·24 h) (Example: 2 times / (1000 holes·24 h)); Frequency of decapitation: 6.9 times / 10 6 m (Example: 4.5 times / 10) 6 m); Defect rate: 1.4% (Example: 0.8%) Conclusion: Without uniform temperature insulation, localized temperature unevenness leads to viscosity differences, causing an imbalance in the distribution of flow rate and tensile force in the pores, resulting in decreased stability under fine denier conditions.

[0054] Comparative Example 4 Compared with the Pt perforated plate in the embodiment, the difference is that the Pt porous perforated plate is replaced with a high-alumina ceramic or Fe–Ni–Cr alloy (800 series) porous component; the temperature zone setting and liquid level closed loop remain unchanged, and the target wire diameter is 11μm.

[0055] result: After running at 1200–1400℃ for 200–300 h, microcracks and penetration appeared in ceramic parts, and obvious corrosion / penetration appeared in Fe–Ni–Cr parts; D50 / COV: 11.3μm / 6.0% (Pt: 11.0μm / 3.0%); Hole plugging: 12 times / (1000 holes·24 h) (Pt: 1–2 times / (1000 holes·24 h)); Frequency of decapitation: 12.4 times / 10 6 m(Pt: 3–4 times / 10) 6 m); Defect rate: 2.5% (Pt: 0.7–0.9%); Maintenance frequency: Frequent load reduction or shutdown is required for replacement (Pt: quick replacement 30–45 min, >1500 h cycle); Conclusion: Non-precious metal parts have insufficient corrosion resistance and thermal stability in basalt melt, which easily induces pore blockage and defect accumulation, and is not conducive to long-term stable wire drawing.

[0056] Although embodiments of the invention have been shown and described, those skilled in the art will be able to make various changes, modifications, substitutions and alterations to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A fully electric melting vertical kiln for basalt fiber production, characterized in that, include: A vertical furnace body (1) is provided with a melting zone (10), a clarifying zone (11) and a drawing zone (12) arranged sequentially along the height direction; multiple sets of molybdenum electrodes (3) are arranged in each zone, and the molybdenum electrodes (3) are connected to the power supply via transformers and power regulators to form a zoned heating system; thermocouples (2) and temperature control units are set in each zone to form a closed-loop control of the temperature of each zone; a liquid level probe is used to detect the liquid level of the molten pool, and the liquid level probe is linked with the automatic feeding mechanism to maintain the preset liquid level; a temperature-controlled discharge chamber (6) and a drawing unit are connected to the drawing zone (12); a precious metal porous baffle plate is set at the bottom of the temperature-controlled discharge chamber (6), and an array of baffles (8) for the outflow of molten basalt is provided on it.

2. The all-electric melting vertical kiln for basalt fiber production according to claim 1, characterized in that: The working temperatures of the melting zone (10), the clarifying zone (11) and the drawing zone (12) are 1500–1600℃, 1400–1480℃ and 1350–1450℃, respectively; the working temperature of the drawing zone (12) is lower than that of the clarifying zone (11).

3. A fully electric melting vertical kiln for basalt fiber production according to claim 1 or 2, characterized in that: The precious metal porous sprue is made of Pt, and the pore diameter of the pores (8) on the precious metal porous sprue is 1.6–2.2 mm, and the number of pores is 800–2000.

4. A fully electric melting vertical kiln for basalt fiber production according to claim 1, characterized in that: The target liquid level height of the molten pool is 360–400 mm.

5. A fully electric melting vertical kiln for basalt fiber production according to claim 1, characterized in that: It also includes a waste wire recycling and remelting channel (9), which is used to return the waste wire generated during the wire drawing process to the furnace body for remelting, so that the overall raw material utilization rate is not less than 95%.

6. The all-electric melting vertical kiln for basalt fiber production according to claim 1, characterized in that: The temperature control unit and the power regulator constitute a zoned power programmable control to form a stable temperature gradient along the height direction.

7. A fully electric melting vertical kiln for basalt fiber production according to claim 1, characterized in that: The temperature-controlled discharge chamber (6) is equipped with temperature equalization and heat preservation components to ensure that the temperature difference between the upstream and downstream of the precious metal porous sluice plate is ≤10℃, thereby improving the temperature uniformity of the area of ​​the precious metal porous sluice plate. The temperature equalization and heat preservation components include a first molybdenum electrode (5), a first thermocouple (4), and a water-cooling pipe (7).

8. A fully electric melting vertical kiln for basalt fiber production according to claim 1, characterized in that: The multiple sets of molybdenum electrodes (3) are arranged symmetrically in layers along the height direction. The molybdenum electrode (3) in the melting zone (10) is the main power supply electrode, the molybdenum electrode (3) in the clarifying zone (11) is the auxiliary electrode, and the molybdenum electrode (3) in the drawing zone (12) is the fine-tuning electrode.

9. A method for melting and drawing basalt fibers, based on the all-electric melting kiln for basalt fiber production as described in claim 1, characterized in that, Includes the following steps: S1. Add basalt granular raw material to the vertical furnace body (1). S2. Under the zoned energy supply and closed-loop temperature control of multiple molybdenum electrodes (3), the raw material is melted in the melting zone (10), purified in the clarification zone (11), and the discharge temperature is kept stable in the drawing zone (12), forming a temperature gradient along the height direction. S3. Maintain a constant liquid level in the molten pool through a liquid level probe and an automatic feeding mechanism; S4. The molten basalt flows out through the array of perforations (8) of the precious metal porous baffle plate at the bottom of the furnace; S5. Under the action of the temperature-controlled discharge chamber (6) and the drawing unit, the outflowing molten basalt is stretched, oiled and wound to obtain continuous basalt fibers.

10. The basalt fiber melt drawing method according to claim 9, characterized in that: Step S3 uses a proportional-integral-derivative or equivalent control algorithm to perform liquid level-feed linkage.

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