Control method for automatic oxygen blowing refining of industrial silicon

Abstract

The invention relates to the technical field of non-ferrous metal smelting, in particular to a control method for automatic oxygen blowing refining of industrial silicon. Comprising the following steps: monitoring the melt temperature in the refining furnace in real time through an infrared temperature measuring device, and continuously collecting the CO concentration in the furnace through a gas analyzer. Establishing a two-parameter oxygen blowing trigger mechanism based on the melt temperature change rate and the CO concentration threshold; when the triggering condition is met, the initial oxygen blowing rate and the spray gun insertion depth are automatically calculated according to the current working condition; gradient oxygen blowing is implemented through multi-stage distributed spray guns, and the oxygen supply amount of each spray gun is independently adjusted according to the temperature distribution of an area where the spray gun is located; dynamically monitoring the state change of the slag, and correcting oxygen blowing parameters in real time according to the thickness and fluidity of a slag layer; a pressure compensation algorithm is adopted to keep the pressure of the oxygen blowing system stable, and the influence of pipeline pressure fluctuation on oxygen supply precision is eliminated. According to the invention, the problems of low control precision, high energy consumption and large product quality fluctuation in the prior art are solved, and the requirements of large-scale production of high-purity industrial silicon are met.

Description

Technical Field

[0001] The invention relates to the technical field of nonferrous metal smelting, and in particular to a control method for automatic oxygen blowing refining of industrial silicon. Background Art

[0002] Industrial silicon is a key raw material for photovoltaics, electronics, and alloys. Its refining purity directly impacts the performance of downstream products. Traditional industrial silicon refining relies on an oxygen decarburization process, where oxygen is blown into the molten silicon to oxidize impurities and form slag, achieving purification.

[0003] However, existing technologies have significant drawbacks in practical application: conventional methods often rely on manual experience or a single parameter (such as temperature or CO concentration) to trigger oxygen blowing, lacking a comprehensive understanding of the dynamic reactions of the melt, which can easily lead to insufficient oxidation or over-blowing. Traditional fixed lance layouts struggle to adapt to spatial variations in temperature gradients and reaction rates within the furnace, leading to an imbalance in oxidation reactions between the center and edge regions, easily causing localized overheating or uneven slag distribution, affecting refining consistency. Summary of the Invention

[0004] The present invention provides an industrial silicon automatic oxygen blowing refining control method that can integrate multi-dimensional parameters such as melt temperature, gas concentration and slag layer state, and has adaptive adjustment capabilities, so as to solve the problems of low control accuracy, high energy consumption and large fluctuations in product quality in the existing technology, and meet the needs of large-scale production of high-purity industrial silicon.

[0005] The technical solution adopted by the present invention is: a control method for automatic oxygen blowing refining of industrial silicon, comprising the following steps:

[0006] Step 1: Monitor the melt temperature in the refining furnace in real time using an infrared temperature measuring device, and continuously collect the CO concentration in the furnace using a gas analyzer;

[0007] Step 2: Establish a dual-parameter oxygen blowing trigger mechanism based on the melt temperature change rate and CO concentration threshold;

[0008] Step 3: When the trigger conditions are met, the initial oxygen blowing rate and the lance insertion depth are automatically calculated according to the current working conditions;

[0009] Step 4: Gradient oxygen blowing is implemented through multi-stage distributed spray guns, and each spray gun independently adjusts the oxygen supply according to the temperature distribution in the area;

[0010] Step 5: Dynamically monitor changes in slag state and modify oxygen blowing parameters in real time based on slag layer thickness and fluidity;

[0011] Step 6: Use pressure compensation algorithm to maintain stable pressure of oxygen blowing system and eliminate the influence of pipeline pressure fluctuation on oxygen supply accuracy.

[0012] As a further improvement of the present invention, the dual-parameter trigger mechanism in step 2 is specifically as follows: when the melt temperature rise rate exceeds 0.8-1.2°C / s and the CO concentration is lower than 3.5-4.5vol%, the first stage of oxygen blowing is started; when the melt temperature reaches 1520-1550°C and the CO concentration is higher than 6.5-7.5vol%, the second stage of enhanced oxygen blowing is started.

[0013] As a further improvement of the present invention, when the second stage of enhanced oxygen blowing is implemented, the gas stirring device arranged at the bottom of the furnace is synchronously activated, and the stirring intensity is increased in a step-by-step manner as the CO concentration increases. When the CO concentration reaches the upper limit of 7.5 vol%, the maximum stirring power is started.

[0014] As a further improvement of the present invention, the gradient oxygen blowing in step 4 specifically includes: dividing the spray gun array into three control areas: a central area, a transition area, and an edge area; the spray gun in the central area adopts pulsed oxygen supply, with a single oxygen supply duration of 8-12 seconds and an interval time of 3-5 seconds; the spray gun in the transition area implements continuous oxygen supply, and the oxygen supply rate is set at 60-80% of the oxygen supply in the central area; the spray gun in the edge area performs intermittent oxygen supply according to the furnace wall temperature monitoring value.

[0015] As a further improvement of the present invention, the transition zone spray gun is equipped with a rotating oxygen supply mechanism. When the cumulative oxygen supply of the edge zone spray gun reaches a set threshold, the transition zone spray gun is controlled to radially swing at a speed of 5-8r / min to supply oxygen.

[0016] As a further improvement of the present invention, the duration of the pulsed oxygen supply is dynamically correlated with the real-time temperature of the melt. When the temperature exceeds 1500°C, the duration of the single oxygen supply is shortened by 0.8-1.2 seconds for every 10°C increase in temperature.

[0017] As a further improvement of the present invention, the slag layer status monitoring in step five is performed; a microwave thickness measuring device installed on the side wall of the furnace body measures the slag layer thickness in real time; the slag layer fluidity is indirectly judged by analyzing the furnace mouth flame morphological characteristics through an image recognition system; and the mechanical slag removal program is automatically started when the slag layer thickness exceeds 120-150mm.

[0018] As a further improvement of the present invention, during the execution of the mechanical slag removal program, the oxygen supply angle of the edge area spray gun is adjusted to an elevation angle of 45-60 degrees, and the insertion depth of the center area spray gun is increased by 20-30 mm to form a protective air curtain.

[0019] As a further improvement of the present invention, the image recognition system is equipped with a spectrum analysis module, which automatically triggers the emergency oxygen stop program and starts nitrogen inerting protection when a sudden increase in the light intensity of 590-620nm wavelength in the flame is detected.

[0020] Beneficial effects of the present invention:

[0021] (1) This invention establishes a dual-parameter trigger mechanism based on the melt temperature change rate and the CO concentration threshold, and dynamically adjusts the oxygen blowing strategy based on real-time working conditions, effectively solving the problem of insufficient or over-oxidation caused by traditional methods that rely on a single parameter. The dual-stage oxygen blowing mode (basic oxygen blowing in the first stage and enhanced oxygen blowing in the second stage) is linked with the gas stirring device in a stepped manner, significantly accelerating the oxidation reaction of impurities, shortening the refining cycle, while avoiding excessive oxidation loss of silicon liquid and improving metal yield.

[0022] (2) The present invention uses a multi-stage distributed spray gun array to divide the control area, combines pulsed, continuous, and intermittent gradient oxygen supply strategies, and introduces a rotating oxygen supply mechanism to dynamically adjust the oxygen supply mode, accurately matching the temperature distribution and reaction requirements of different areas within the furnace. The synergistic effect of the protective air curtain in the center area and the angled oxygen supply in the edge area further suppresses local overheating and uneven slag layer distribution, ensuring a uniform and stable melt oxidation reaction, and improving product composition consistency by more than 15%.

[0023] (3) The present invention uses microwave thickness measurement, image recognition, and spectral analysis technology to monitor the slag layer status and flame characteristics in real time, and forms a closed-loop linkage control with oxygen blowing parameters and mechanical slag removal procedures. The pressure compensation algorithm and dynamic oxygen supply adjustment mechanism effectively eliminate system interference, achieving an oxygen supply pressure fluctuation range of ≤±2%. Under abnormal operating conditions (such as abnormal flame spectrum), emergency oxygen shutdown and inerting protection are automatically triggered, significantly improving production safety and process controllability, and reducing the need for manual intervention by more than 30%. DETAILED DESCRIPTION

[0024] In order to make the technical problems, technical solutions and beneficial effects to be solved by this application more clearly understood, this application is further described in detail below in conjunction with the embodiments. It should be understood that the embodiments described herein are only used to explain this application and are not intended to limit this application.

[0025] The present invention provides a control method for automatic oxygen blowing refining of industrial silicon, comprising the following steps:

[0026] Step 1: Monitor the melt temperature in the refining furnace in real time using an infrared temperature measuring device, and continuously collect the CO concentration in the furnace using a gas analyzer;

[0027] Step 2: Establish a dual-parameter oxygen blowing trigger mechanism based on the melt temperature change rate and CO concentration threshold;

[0028] Step 3: When the trigger conditions are met, the initial oxygen blowing rate and the lance insertion depth are automatically calculated according to the current working conditions;

[0029] Step 4: Gradient oxygen blowing is implemented through multi-stage distributed spray guns, and each spray gun independently adjusts the oxygen supply according to the temperature distribution in the area;

[0030] Step 5: Dynamically monitor changes in slag state and modify oxygen blowing parameters in real time based on slag layer thickness and fluidity;

[0031] Step 6: Use pressure compensation algorithm to maintain stable pressure of oxygen blowing system and eliminate the influence of pipeline pressure fluctuation on oxygen supply accuracy.

[0032] In the present invention, the dual-parameter trigger mechanism in step 2 is specifically as follows: when the melt temperature rise rate exceeds 0.8-1.2°C / s and the CO concentration is lower than 3.5-4.5vol%, the first stage of oxygen blowing is started; when the melt temperature reaches 1520-1550°C and the CO concentration is higher than 6.5-7.5vol%, the second stage of enhanced oxygen blowing is started; when the second stage of enhanced oxygen blowing is implemented, the gas stirring device arranged at the bottom of the furnace is synchronously activated, and the stirring intensity increases in a step-by-step manner with the increase of CO concentration. When the CO concentration reaches the upper limit of 7.5vol%, the maximum stirring power is started.

[0033] In the present invention, the gradient oxygen blowing in step 4 specifically includes: dividing the spray gun array into three control areas: a central area, a transition area, and an edge area; the spray gun in the central area adopts pulsed oxygen supply, with a single oxygen supply duration of 8-12 seconds and an interval time of 3-5 seconds; the spray gun in the transition area implements continuous oxygen supply, and the oxygen supply rate is set at 60-80% of the oxygen supply in the central area; the spray gun in the edge area performs intermittent oxygen supply according to the furnace wall temperature monitoring value.

[0034] In the present invention, the transition zone spray gun is equipped with a rotating oxygen supply mechanism. When the cumulative oxygen supply of the edge zone spray gun reaches a set threshold, the transition zone spray gun is controlled to radially swing at a speed of 5-8 r / min to supply oxygen.

[0035] In the present invention, the duration of the pulsed oxygen supply is dynamically correlated with the real-time temperature of the melt. When the temperature exceeds 1500°C, the duration of the single oxygen supply is shortened by 0.8-1.2 seconds for every 10°C increase in temperature.

[0036] In the present invention, the slag layer status monitoring in step five is passed; a microwave thickness measuring device installed on the side wall of the furnace body measures the slag layer thickness in real time; the slag layer fluidity is indirectly judged by analyzing the furnace mouth flame morphological characteristics through an image recognition system; and the mechanical slag removal program is automatically started when the slag layer thickness exceeds 120-150mm.

[0037] In the present invention, during the execution of the mechanical slag removal program, the oxygen supply angle of the edge zone spray gun is adjusted to an elevation angle of 45-60 degrees, and the insertion depth of the center zone spray gun is increased by 20-30 mm to form a protective air curtain.

[0038] In the present invention, the image recognition system is equipped with a spectrum analysis module, which automatically triggers the emergency oxygen stop program and starts nitrogen inerting protection when a sudden increase in the light intensity of 590-620nm wavelength in the flame is detected.

[0039] Example:

[0040] A refining workshop with an annual output of 100,000 tons of high-purity industrial silicon adopts this control method to implement oxygen blowing refining. The specific implementation process is as follows.

[0041] (1) Initial parameter configuration and device startup

[0042] Three infrared thermometers (KLEIBER 815-LO, ±2°C accuracy) were installed at different levels within the furnace, and a gas analyzer (SIEMENS ULTRAMAT 23) was sampled at a rate of 1 time per second. The spray gun array consisted of 12 water-cooled guns, arranged concentrically into a central zone (4), a transition zone (4), and an edge zone (4). The guns were equipped with a motorized lift mechanism (±1mm accuracy) and a rotary actuator. Six gas agitators (adjustable power from 0 to 30kW) were installed in a circular arrangement at the furnace bottom.

[0043] (2) First stage oxygen blowing trigger

[0044] When the initial melt temperature was 1480°C, the temperature rise rate was detected to be 1.0°C / s (exceeding the set threshold of 0.8°C / s), and the CO concentration dropped to 4.0 vol% (below the threshold of 4.2 vol%). The control system immediately executed the following actions: (1) The central zone spray gun was started in pulse mode, with a single oxygen supply of 10 seconds (oxygen flow rate of 12m 3 / h), with an interval of 4 seconds; (2) The transition zone is supplied with oxygen continuously at 70% of the flow rate of the central zone (8.4m 3 (3) In the edge zone, intermittent oxygen supply (oxygen supply 5 seconds / stop 15 seconds) is started according to the furnace wall temperature (monitored value 1420°C). At this time, the injection depth of the spray gun is set to 150mm in the center zone, 120mm in the transition zone, and 100mm in the edge zone.

[0045] (3) Dynamic parameter adjustment

[0046] When the melt temperature rises to 1510°C, the system automatically shortens the pulse oxygen supply time: (1) For every 10°C increase in temperature, the single oxygen supply time is reduced by 1 second; (2) the current temperature is 10°C higher than the baseline (1500°C), so the pulse oxygen supply time is adjusted to 9 seconds. At the same time, the temperature gradient difference at the edge of the transition zone is detected to be 35°C, triggering the rotary oxygen supply condition: the transition zone spray gun is radially oscillated at 6 rpm to expand the oxygen coverage area.

[0047] (IV) Second stage of enhanced oxygen blowing

[0048] When the temperature reaches 1535℃ and the CO concentration rises to 7.0vol%: (1) the central zone spray gun is switched to continuous oxygen supply (the flow rate is increased to 15m 3 / h); (2) Activate the furnace bottom gas stirring device and start secondary stirring (18kW) at a CO concentration of 7.0vol%; (3) Increase the penetration depth of the spray gun: 170mm in the center area and 140mm in the transition area, to achieve deep penetration.

[0049] (5) Collaborative control of slag layer

[0050] When the microwave thickness measuring device (MTS-600) monitors the slag layer thickness at 135 mm: (1) the mechanical slag scraper is automatically started at a scraping speed of 0.5 m / s; (2) the spray gun in the edge area is adjusted to a 55° elevation angle, and the insertion depth of the spray gun in the center area is increased to 200 mm; (3) the oxygen supply in the transition zone is maintained at 50% during the scraping process to prevent secondary oxidation of the melt.

[0051] (6) Handling of abnormal working conditions

[0052] At the end of refining, the image recognition system detected that the intensity of the 605nm wavelength light in the flame suddenly increased by 300% within 2 seconds, which was determined to be abnormal oxidation: (1) immediately cut off the oxygen supply to all spray guns (response time < 0.5 seconds); (2) turned on the nitrogen inerting system (flow rate 40m 3 / min, for 30 seconds); (3) trigger the sound and light alarm and upload the abnormal data to the central control system.

[0053] (7) Refining results

[0054] After refining, the test shows:

[0055] index Traditional crafts Process of the present invention Improvement effect Refining cycle 210 minutes 165min 21.4％ Silicon liquid oxygen content 520ppm 285ppm 45.2％ Slag layer uniformity 62％ 89％ 43.5％ Ton of silicon oxygen consumption <![CDATA[48m 3 ]]> <![CDATA[37m 3 ]]> 22.9％

[0056] Through coordinated control of multiple parameters, this embodiment achieved an increase in the oxidation rate of impurity elements from 88.7% in the traditional process to 96.3%, while reducing the silicon loss rate from 4.2% to 2.8%, verifying the significant advantages of this control method in improving product quality and reducing energy consumption.

[0057] In summary, the automatic oxygen blowing refining control method for industrial silicon of the present invention achieves adaptive and precise control of the refining process by integrating multi-dimensional parameters such as melt temperature, gas concentration, and slag layer state. This method not only significantly shortens the refining cycle, reduces the oxygen content of silicon liquid and the oxygen consumption per ton of silicon, but also significantly improves the uniformity of the slag layer and product quality. In addition, the application of this control method effectively reduces the need for manual intervention, improves production safety and process controllability, and provides strong technical support for the large-scale production of high-purity industrial silicon.

[0058] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A control method for automatic oxygen blowing refining of industrial silicon, characterized in that: The following steps are involved: Step 1: Monitor the melt temperature in the refining furnace in real time using an infrared temperature measuring device, and continuously collect the CO concentration in the furnace using a gas analyzer; Step 2: Establish a dual-parameter oxygen blowing trigger mechanism based on the melt temperature change rate and CO concentration threshold; Step 3: When the trigger conditions are met, the initial oxygen blowing rate and the lance insertion depth are automatically calculated according to the current working conditions; Step 4: Gradient oxygen blowing is implemented through multi-stage distributed spray guns, and each spray gun independently adjusts the oxygen supply according to the temperature distribution in the area; Step 5: Dynamically monitor changes in slag state and modify oxygen blowing parameters in real time based on slag layer thickness and fluidity; Step 6: Use pressure compensation algorithm to maintain stable pressure of oxygen blowing system and eliminate the influence of pipeline pressure fluctuation on oxygen supply accuracy.

2. The control method for automatic oxygen blowing refining of industrial silicon according to claim 1, characterized in that: The dual-parameter trigger mechanism in step 2 is specifically as follows: when the melt temperature rise rate exceeds 0.8-1.2°C / s and the CO concentration is lower than 3.5-4.5vol%, the first stage of oxygen blowing is started; when the melt temperature reaches 1520-1550°C and the CO concentration is higher than 6.5-7.5vol%, the second stage of enhanced oxygen blowing is started.

3. The control method for automatic oxygen blowing refining of industrial silicon according to claim 2, characterized in that: When the second stage of enhanced oxygen blowing is implemented, the gas stirring device arranged at the bottom of the furnace is simultaneously activated. The stirring intensity increases in a step-by-step manner as the CO concentration increases, and the maximum stirring power is started when the CO concentration reaches the upper limit of 7.5 vol%.

4. The control method for automatic oxygen blowing refining of industrial silicon according to claim 1, characterized in that: The gradient oxygen blowing in step 4 specifically includes: dividing the spray gun array into three control areas: a central area, a transition area, and an edge area; the spray gun in the central area adopts pulsed oxygen supply, with a single oxygen supply duration of 8-12 seconds and an interval time of 3-5 seconds; the spray gun in the transition area implements continuous oxygen supply, and the oxygen supply rate is set at 60-80% of the oxygen supply in the central area; the spray gun in the edge area performs intermittent oxygen supply according to the furnace wall temperature monitoring value.

5. The control method for automatic oxygen blowing refining of industrial silicon according to claim 4, characterized in that: The transition zone spray gun is equipped with a rotating oxygen supply mechanism. When the cumulative oxygen supply of the edge zone spray gun reaches a set threshold, the transition zone spray gun is controlled to radially swing at a speed of 5-8 r / min to supply oxygen.

6. The control method for automatic oxygen blowing refining of industrial silicon according to claim 4, characterized in that: The duration of the pulsed oxygen supply is dynamically correlated with the real-time temperature of the melt. When the temperature exceeds 1500°C, the duration of the single oxygen supply is shortened by 0.8-1.2 seconds for every 10°C increase in temperature.

7. The control method for automatic oxygen blowing refining of industrial silicon according to claim 1, characterized in that: The slag layer status monitoring in step 5 is passed; a microwave thickness measuring device installed on the side wall of the furnace body measures the slag layer thickness in real time; the slag layer fluidity is indirectly determined by analyzing the furnace mouth flame morphological characteristics through an image recognition system; and the mechanical slag removal program is automatically started when the slag layer thickness exceeds 120-150mm.

8. The control method for automatic oxygen blowing refining of industrial silicon according to claim 7, characterized in that: During the execution of the mechanical slag removal procedure, the oxygen supply angle of the edge area spray gun is adjusted to an elevation angle of 45-60 degrees, and the insertion depth of the center area spray gun is increased by 20-30 mm to form a protective air curtain.

9. The control method for automatic oxygen blowing refining of industrial silicon according to claim 7, characterized in that: The image recognition system is equipped with a spectrum analysis module, which automatically triggers the emergency oxygen stop program and starts nitrogen inerting protection when a sudden increase in the light intensity of 590-620nm wavelength in the flame is detected.