A tin smelting combined blown furnace and smelting method thereof

Abstract

This invention discloses a tin smelting double-blown furnace and its smelting method, including a tin smelting double-blown furnace, an air storage unit, an oxygen-enriched air storage unit, and a gas conveying unit; the gas conveying unit includes a branch conveying pipe; a jetting unit is disposed at the outlet end of the branch conveying pipe, including a first nozzle disposed on the bottom wall of the tin smelting double-blown furnace and a second nozzle disposed on the side wall of the tin smelting double-blown furnace; the inlet ends of both the first nozzle and the second nozzle are connected to the branch conveying pipe. This invention enhances the stirring ability of the melt in the corner area of ​​the furnace by adding a first nozzle as a bottom blowing device at the bottom of the tin smelting double-blown furnace, reducing the occurrence of melt scouring in this area; by adding a second nozzle as a side blowing device on the side wall of the tin smelting double-blown furnace, when the molten pool level increases, it can not only strongly stir the molten pool, maximize the metallurgical kinetic conditions, and increase the processing capacity per unit furnace bed area, but also reduce the melt splashing phenomenon caused by bottom blowing by utilizing the high-speed airflow of the side blowing.

Description

Technical Field

[0001] This invention belongs to the field of crude tin smelting technology, and specifically relates to a tin smelting double-blown furnace and its smelting method. Background Technology

[0002] Tin smelting processes mainly include electric furnace smelting, reverberatory furnace smelting, and imported Osmette furnace smelting. Electric furnace smelting is highly adaptable to raw materials, especially superior for tin concentrates containing high melting points such as tungsten, tantalum, and niobium. It produces less flue gas and has a tin volatilization rate as low as 1.3%. Its disadvantage is that the reducing atmosphere is too strong, making it unsuitable for tin concentrates with an iron content higher than 5%. Reverberatory furnace smelting is the traditional tin smelting method and the most widely used equipment for reducing and smelting tin concentrates. It has advantages such as low investment cost, simple structure, convenient operation, and strong adaptability to raw materials. However, with the advancement of other smelting technologies, such as flash smelting and pool smelting, it has inherent drawbacks such as low furnace bed efficiency, low heat utilization, high labor intensity, poor environmental conditions, and poor technical and economic indicators. Furthermore, as the grade of tin concentrate decreases, the impurities become more complex and abundant, resulting in a high rate of ethylene tin and hardened ends during the smelting process, leading to a very long subsequent refining process and persistently high smelting costs. The imported Osmet tin smelting process has the advantages of molten pool smelting, such as high bed energy efficiency and low energy consumption. However, the technology import cost is high, the service life of the spray gun is only 5-7 days, the oxygen enrichment concentration is only 30%, the furnace life is only 1-2 years, and there are problems such as dead zone of stirring, nozzle wear, and uneven gas distribution during the smelting process.

[0003] Therefore, providing a low-cost, efficient, and energy-saving smelting furnace and smelting process for crude tin is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0004] The purpose of this invention is to provide a tin smelting furnace and its smelting method, so as to solve the problems of uneven gas distribution, the existence of dead zones in stirring, local cooling of the molten pool, uneven reaction effect, and unstable temperature and chemical reaction in the tin smelting process.

[0005] To achieve the above objectives, the present invention provides a tin smelting double-blown furnace, comprising: Tin smelting double-blown furnace; An air storage unit is located on one side of the tin smelting reblowing furnace and is used to store air; An oxygen-enriched air storage unit is disposed on one side of the air storage unit and is used to store oxygen-enriched air; The gas delivery unit includes a branch delivery pipe connected to the air storage unit and the oxygen-enriched air storage unit, and the branch delivery pipe is connected to the tin smelting reblowing furnace. The jetting unit, located at the outlet end of the diversion conveying pipe, includes multiple first nozzles located on the bottom wall of the tin smelting reblown furnace and multiple second nozzles located on the side wall of the tin smelting reblown furnace; the inlet ends of the first and second nozzles are both connected to the diversion conveying pipe.

[0006] Preferably, the air storage unit includes an air storage chamber, an air inlet is provided at the upper end of the air storage chamber, an air outlet is provided at the lower end of the air storage chamber, and a first valve is provided on the air outlet.

[0007] Preferably, the oxygen-enriched air storage unit includes an oxygen-enriched air storage chamber, an oxygen-enriched air inlet is provided at the upper end of the oxygen-enriched air storage chamber, an oxygen-enriched air outlet is provided at the lower end of the oxygen-enriched air storage chamber, and a second valve is provided on the oxygen-enriched air outlet.

[0008] Preferably, both the air outlet and the oxygen-enriched air outlet are connected to the diversion and delivery pipe, which collects the air and the oxygen-enriched air within it.

[0009] Preferably, the plurality of first nozzles are all tapered nozzles, and are equally spaced at the junction of the bottom wall and the side wall of the tin smelting blown furnace; the angle between the center line of the first nozzle and the bottom wall of the tin smelting blown furnace is 45°, and the angle between the centers of two adjacent first nozzles is 90°.

[0010] Preferably, the plurality of second nozzles are all tapered nozzles, and are vertically arranged at equal intervals on the side wall of the tin smelting reblown furnace; the included angle between the centers of each two adjacent second nozzles is 90°, and the distance between the second nozzle and the bottom wall of the tin smelting reblown furnace is one-tenth of the overall height of the tin smelting reblown furnace.

[0011] Preferably, an air pump is installed on the diversion and delivery pipe, and the air pump has a delivery speed of 15,000-40,000 Nm. 3 / h, conveying pressure is 0.5-1MPa.

[0012] Preferably, the tin smelting reblowing furnace is provided with a belt conveyor feed inlet, a top blowing gun is provided on one side of the belt conveyor feed inlet, and a furnace top sampling rod is provided on one side of the top blowing gun.

[0013] A tin smelting method using a double-blown furnace, specifically comprising the following steps: The bottom material is fed into the tin smelting furnace through the belt conveyor inlet. Once the bottom material reaches a predetermined height, tin-containing raw materials, flux, and reducing coal are fed into the furnace through the belt conveyor inlet. Simultaneously, one or more of compressed air mixed with fuel, oxygen, and oxygen-enriched gas are injected into the furnace through the top-blown nozzle, causing the melt to vortex and churn. Simultaneously, one or more of air and oxygen-enriched air are injected through the first nozzle, causing the melt to churn and form numerous dispersed bubbles, allowing the melt to... A violent reaction occurs in the pool area, initiating the first stage of weak reduction reaction. Reducing coal continues to be fed into the furnace through the conveyor belt feed port to maintain the reducing atmosphere. If the second nozzle is immersed in the melt, it also injects one or more types of air and oxygen-enriched air, causing the melt to swirl and churn. Feeding is stopped, and the reduction stage begins. Slag samples are taken during the smelting process using a sampling rod at the top of the furnace for analysis to determine the tin and slag discharge stages and the degree of smelting progress. When the analysis shows that the tin content in the slag is ≤5%, tin and slag discharge begins, and the discharged crude tin is sent to the refining process for processing.

[0014] Compared with the prior art, the beneficial effects of the present invention are: This invention enhances the stirring ability of the melt in the corner area of ​​the tin smelting double-blown furnace by adding a first nozzle as a bottom-blowing device, reducing melt scouring in this area and effectively extending the furnace's service life. A second nozzle is added to the side wall of the tin smelting double-blown furnace as a side-blowing device. When the molten pool level increases, it not only strongly stirs the molten pool, maximizing metallurgical kinetics and increasing the processing capacity per unit furnace bed area, but also uses high-speed side-blowing airflow to reduce melt splashing caused by bottom blowing. The furnace top sampling rod can sample and test the slag composition in the core reaction area of ​​the top-blown furnace at any time, allowing for better assessment of the reaction conditions and whether the generated crude tin meets industrial requirements. This top-bottom-side double-blown furnace and process effectively improves existing problems in top-blown furnaces, such as dead zones, uneven gas distribution, and nozzle wear. It also provides better thermodynamic and kinetic conditions, increasing bed capacity and production efficiency, improving tin recovery rate, enhancing environmental protection, and reducing production and operating costs. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 For the present invention Figure 1 Schematic diagram of the middle-diversion delivery pipe structure.

[0016] Reference numerals: 1. Top-blown spray gun; 2. Sampling rod at the top of the furnace; 3. Belt conveyor feed inlet; 4. Tin smelting re-blowing furnace; 5. Second nozzle; 6. First nozzle; 8. Air pump; 9. Diverting conveying pipe; 10. Air storage unit; 101. Air inlet; 102. Air storage chamber; 103. Air outlet; 11. Oxygen-enriched air storage unit; 111. Oxygen-enriched air inlet; 112. Oxygen-enriched air storage chamber; 113. Oxygen-enriched air outlet. Detailed Implementation

[0017] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Example 1

[0018] This embodiment provides a tin smelting double-blown furnace, including: a tin smelting double-blown furnace 4, an air storage unit 10, an oxygen-enriched air storage unit 11, a gas conveying unit, and a jetting unit.

[0019] Specifically, participate Figure 1 The furnace includes a tin smelting reblown furnace 4, an air storage unit 10 for storing air disposed on one side of the tin smelting reblown furnace, an oxygen-enriched air storage unit 11 for storing oxygen-enriched air disposed on one side of the air storage unit 10, a gas conveying unit including a diversion conveying pipe 9 connected to the air storage unit 10 and the oxygen-enriched air storage unit 11, the diversion conveying pipe 9 being connected to the tin smelting reblown furnace, and an air jetting unit disposed at the outlet end of the diversion conveying pipe 9, including a plurality of first nozzles 6 disposed on the bottom wall of the tin smelting reblown furnace, and a plurality of second nozzles 5 disposed on the side wall of the tin smelting reblown furnace; the inlet ends of the first nozzles 6 and the second nozzles 5 are both connected to the diversion conveying pipe.

[0020] Optionally, the height of the tin smelting double-blown furnace 4 is 12m.

[0021] Existing tin smelting double-blown furnaces suffer from problems during tin smelting due to uneven gas distribution, the presence of dead zones leading to localized cooling of the molten pool, uneven reaction effects, and unstable temperature and chemical reactions. To address these issues, a first nozzle 6 is added to the bottom of the existing top-blown tin smelting furnace 4 as a bottom-blowing device. This enhances the stirring ability of the melt in the corner areas of the furnace, reducing melt scouring in these areas and effectively extending the furnace's service life. A second nozzle 5 is added to the side wall of the tin smelting double-blown furnace 4 as a side-blowing device. When the molten pool level increases, this not only strongly stirs the molten pool, maximizing metallurgical kinetics and increasing the processing capacity per unit furnace bed area, but also reduces melt splashing caused by bottom blowing using high-speed side-blowing airflow. The furnace top sampling rod 2 allows for continuous sampling and testing of the slag composition in the core reaction zone of the top-blown furnace, enabling better assessment of the reaction conditions within the furnace and whether the produced crude tin meets industrial requirements. The top-bottom-side combined blowing furnace and process method for tin smelting can effectively improve the problems of dead zones, uneven gas distribution, and nozzle wear in existing top-blown furnaces. It also has better thermodynamic and kinetic conditions, improved bed capacity and production efficiency, increased tin recovery rate, better environmental protection effect, and reduced production and operating costs.

[0022] As a further improvement to this embodiment, the air storage unit 10 includes an air storage chamber 102, with an air inlet 101 at the upper end and an air outlet 103 at the lower end. A first valve is provided on the air outlet 103. The oxygen-enriched air storage unit 11 includes an oxygen-enriched air storage chamber 112, with an oxygen-enriched air inlet 111 at the upper end and an oxygen-enriched air outlet 113 at the lower end. A second valve is provided on the oxygen-enriched air outlet 113.

[0023] Specifically, the air storage unit 10 and the oxygen-enriched air storage unit 11 are set to output unit time and output delivery speed through the DCS control system, and quantitatively deliver the first valve on the air outlet 103 and the second valve on the oxygen-enriched air outlet 113 to the diversion delivery pipe 9.

[0024] As a further improvement to this embodiment, both the air outlet 103 and the oxygen-enriched air outlet 113 are connected to the diversion and conveying pipe 9, which collects the air and oxygen-enriched air. The air and oxygen-enriched air flow into the diversion and conveying pipe 9 and are then transported to the tin smelting reblowing furnace 4 through the diversion and conveying pipe 9.

[0025] As a further improvement of this embodiment, the plurality of first nozzles 6 are all tapered nozzles, and are equally spaced at the junction of the bottom wall and the side wall of the tin smelting double-blown furnace 4; the angle between the center line of the first nozzle 6 and the bottom wall of the tin smelting double-blown furnace 4 is 45°, and the angle between the centers of two adjacent first nozzles 6 is 90°.

[0026] Specifically, the first nozzle 6 serves as a bottom blowing device, and four nozzles are optimally set. The center points of the four nozzles are connected sequentially to form a square. The angle between the center line of the first nozzle 6 and the bottom wall of the tin smelting combined blowing furnace 4 is 45°. When the center angle between two adjacent first nozzles 6 is 90°, the angle is set optimally. This can significantly enhance the stirring ability of the melt in the corner area of ​​the furnace body, reduce the occurrence of melt scouring in this area, and effectively enhance the service life of the furnace body.

[0027] As a further improvement of this embodiment, the plurality of second nozzles 5 are all tapered nozzles, and are vertically arranged at equal intervals on the side wall of the tin smelting reblown furnace 4; the included angle between the centers of each pair of adjacent second nozzles 5 is 90°, and the distance between the second nozzles 5 and the bottom wall of the tin smelting reblown furnace 4 is one-tenth of the overall height of the tin smelting reblown furnace 4.

[0028] Specifically, the optimal distance between the second nozzle 5 and the bottom wall of the tin smelting combined blowing furnace 4 is one-tenth of the overall height of the tin smelting combined blowing furnace 4. The optimal angle between the centers of any two adjacent second nozzles 5 is also 90°. When the molten pool level increases, it not only strongly stirs the molten pool, maximizing the metallurgical kinetics and increasing the processing capacity per unit furnace area, but also reduces molten splashing caused by bottom blowing by utilizing high-speed side-blowing airflow.

[0029] As a further improvement to this embodiment, an air pump 8 is installed on the diversion and delivery pipe 9, and the delivery speed of the air pump 8 is 15000-40000 Nm. 3 / h, conveying pressure is 0.5-1MPa.

[0030] Specifically, during the process of stopping feeding at the belt conveyor feed inlet 3 and entering the reduction stage, the air pump 8 continues to inject air and oxygen-enriched air through the second nozzle 5 and the first nozzle 6 to prevent the material feed nozzle from being blocked by the slag in the furnace and the melt from churning and forming a large number of dispersed bubbles, thereby strengthening the stirring of the molten pool area, top blowing, and raising the position of the first nozzle.

[0031] As a further improvement of this embodiment, a belt conveyor feed inlet 3 is provided on the tin smelting reblowing furnace 4, a top blowing gun 1 is provided on one side of the belt conveyor feed inlet 3, and a furnace top sampling rod 2 is provided on one side of the top blowing gun 1.

[0032] Specifically, the top-blown lance 1 extends from the outside of the tin smelting double-blown furnace 4, perpendicular to the center of the furnace body, to the bottom of the furnace 4; the top sampling rod 2 extends from the outside of the tin smelting double-blown furnace 4, perpendicular to the wall surface, along the center line of the furnace 4 to below the slag line. The top sampling rod 2 can sample and test the slag composition in the core reaction zone of the top-blown furnace at any time, which can better determine the reaction conditions inside the furnace and whether the generated crude tin meets industrial requirements. Example 2

[0033] The specific workflow of the bottom-feed top-blown furnace treatment method for tin smelting according to an embodiment of the present invention is as follows: Tin-containing materials, flux, and reducing coal are fed into the smelting furnace through the top belt conveyor feed inlet 3. The flux consists of quartz and iron ore. The slag ratio is controlled as Fe:SiO2 = 1.25 and CaO:SiO2 = 0.35. Oxygen-enriched air and fuel are injected into the smelting furnace through the top blowing lance 1. The volume concentration of oxygen in the oxygen-enriched air is 35%.

[0034] When the molten pool depth is 500-700mm, close the second nozzle 5 on the side wall and open the first nozzle 6 at the bottom. Use the DCS control system to open the first valve on the air outlet 103 and the second valve on the oxygen-enriched air outlet 113. Adjust the air pump's delivery pressure to 0.8MPa and the delivery speed to 30000Nm. 3 / h, the airflow converges into the diversion and conveying pipe 9, and then is injected into the molten pool through four bottom first nozzles 6 to melt and stir the melt, promote the melting of the material, and carry out the first stage of weak reduction reaction.

[0035] During the smelting process, feed continues through the controlled belt conveyor feed inlet 3, with reducing coal continuously added to maintain the reducing atmosphere inside the furnace. At regular intervals, the top sampling rod 2 is lowered to observe the amount of raw material carried by the slag sample brought out by the top sampling rod 2, determining the timing for entering the strong reduction stage. Once the strong reduction stage is entered, the amount of reducing coal is increased. After a certain reduction time, the top sampling rod 2 is lowered to collect a slag sample for rapid analysis of the tin content. When the slag sample contains <5% Sn, the tin and slag discharge stage begins, completing the single-furnace smelting process, after which the next furnace cycle begins. Example 3

[0036] Tin smelting methods using a double-blown furnace include: Tin-containing materials, flux, and reducing coal are fed into a 1700mm tin smelting double-blown furnace 4 at a mass ratio of 100:9.5:12.5. The flux consists of quartz and iron ore. The slag ratio is controlled as Fe:SiO2 = 1.25 and CaO:SiO2 = 0.35. The materials are fed into the furnace 4 through a belt conveyor inlet. Oxygen-enriched air and fuel are injected into the furnace 4 through a top-blown lance 1. The volume concentration of oxygen in the oxygen-enriched air is 35%.

[0037] When the depth of the tin smelting blown furnace 4 is 500-700mm, close the second nozzle 5 on the side wall and open the first nozzle 6 at the bottom. Use the DCS control system to open the first valve on the air outlet 103 and the second valve on the oxygen-enriched air outlet 113. Adjust the air pump's delivery pressure to 0.8MPa and the delivery speed to 30000Nm. 3 / h, the airflow converges into the diversion and conveying pipe 9, and then is injected into the molten pool through four bottom first nozzles 6 to melt and stir the melt, promote the melting of the material, and carry out the first stage of weak reduction reaction.

[0038] When the bottom material is continuously fed until the depth of the molten pool is >700mm, open the second nozzle 5 on the side wall, adjust the air pump's delivery pressure to 0.7MPa, and the delivery speed to 20000Nm. 3 At a speed of / h, the airflow is split through the diversion and conveying pipe 9 and then injected into the molten pool through four bottom first nozzles 6 and four side wall second nozzles 5 to melt and stir the molten material, promoting melting. When the bottom material reaches a depth of 1400mm in the molten pool, the feeding of tin-containing materials is stopped. As melting progresses, the gas-liquid interface fluctuates continuously. The second nozzles 5 and the first nozzles 6 continuously inject air and oxygen-enriched air to suppress axial splashing of the molten material while enhancing lateral momentum transmission and expanding the stirring area.

[0039] During the smelting process, feed continues through the controlled belt conveyor feed inlet 3, with reducing coal continuously added to maintain the reducing atmosphere inside the furnace. At regular intervals, the top sampling rod 2 is lowered to observe the amount of raw material carried by the slag sample brought out by the top sampling rod 2, determining the timing for entering the strong reduction stage. Once the strong reduction stage is entered, the amount of reducing coal is increased. After a certain reduction time, the top sampling rod 2 is lowered to collect a slag sample for rapid analysis of the tin content. When the slag sample contains <5% Sn, the tin and slag discharge stage begins, completing the single-furnace smelting process, after which the next furnace cycle begins.

[0040] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0041] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made 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 tin smelting double-blown furnace, characterized in that, include: Tin smelting double-blown furnace (4); An air storage unit (10) is disposed on one side of the tin smelting reblowing furnace and is used to store air; An oxygen-enriched air storage unit (11) is disposed on one side of the air storage unit (10) and is used to store oxygen-enriched air; The gas delivery unit includes a diversion delivery pipe (9) connected to the air storage unit (10) and the oxygen-enriched air storage unit (11), and the diversion delivery pipe (9) is connected to the tin smelting reblowing furnace. The jetting unit is located at the outlet end of the diversion conveying pipe (9) and includes a plurality of first nozzles (6) located on the bottom wall of the tin smelting reblowing furnace and a plurality of second nozzles (5) located on the side wall of the tin smelting reblowing furnace; the inlet ends of the first nozzles (6) and the second nozzles (5) are connected to the diversion conveying pipe. The air storage unit (10) includes an air storage chamber (102), an air inlet (101) is provided at the upper end of the air storage chamber (102), an air outlet (103) is provided at the lower end of the air storage chamber (102), and a first valve is provided on the air outlet (103); The oxygen-enriched air storage unit (11) includes an oxygen-enriched air storage chamber (112), an oxygen-enriched air inlet (111) is provided at the upper end of the oxygen-enriched air storage chamber (112), an oxygen-enriched air outlet (113) is provided at the lower end of the oxygen-enriched air storage chamber (112), and a second valve is provided on the oxygen-enriched air outlet (113). The air outlet (103) and the oxygen-enriched air outlet (113) are both connected to the diversion and delivery pipe (9), which collects the air and the oxygen-enriched air. The first nozzles (6) are all tapered nozzles, and are equally spaced at the junction of the bottom wall and the side wall of the tin smelting reblown furnace (4); the angle between the center line of the first nozzle (6) and the bottom wall of the tin smelting reblown furnace (4) is 45°, and the angle between the centers of two adjacent first nozzles (6) is 90°. Multiple second nozzles (5) are tapered nozzles, and are vertically arranged at equal intervals on the side wall of the tin smelting reblown furnace (4); the included angle between the centers of each two adjacent second nozzles (5) is 90°, and the distance between the second nozzles (5) and the bottom wall of the tin smelting reblown furnace (4) is one-tenth of the overall height of the tin smelting reblown furnace (4); An air pump (8) is installed on the diversion and delivery pipe (9), and the delivery speed of the air pump (8) is 15000-40000 Nm. 3 / h, conveying pressure is 0.5-1MPa; The tin smelting reblowing furnace (4) is provided with a belt conveyor feed inlet (3), a top blowing gun (1) is provided on one side of the belt conveyor feed inlet (3), and a furnace top sampling rod (2) is provided on one side of the top blowing gun (1).

2. A tin smelting method using a double-blown furnace, characterized in that, The smelting process using the tin smelting furnace as described in claim 1 specifically includes the following steps: The bottom material is fed into the tin smelting reblown furnace (4) through the belt conveyor feed inlet (3); when the bottom material in the tin smelting reblown furnace (4) reaches the predetermined height, tin-containing raw materials, flux and reducing coal are fed into the tin smelting reblown furnace (4) through the belt conveyor feed inlet (3); at the same time, one or more of compressed air, oxygen and oxygen-enriched gas mixed with fuel are injected into the tin smelting reblown furnace (4) through the top blowing gun (1) to make the melt vortex and churn; at the same time, one or more of air and oxygen-enriched air are injected into the first nozzle (6) to make the melt churn and form a large number of particles. Disperse the bubbles to cause a violent reaction in the molten pool area and carry out the first stage of weak reduction reaction; continue to feed reducing coal through the feed inlet (3) to maintain the reducing atmosphere in the furnace. If the second nozzle (5) is immersed in the melt, the second nozzle (5) also sprays one or more of air and oxygen-enriched air to make the melt vortex and churn; stop feeding and enter the reduction stage. Take slag samples through the furnace top sampling rod (2) during the smelting process to determine the tin discharge and slag discharge stages and determine the degree of smelting progress; when the analysis shows that the tin content of the molten slag is ≤5%, start tin discharge and slag discharge. The discharged crude tin is sent to the refining process for processing.

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