A method of converting a smelting furnace

Abstract

This invention discloses a smelting method for a fuming furnace. When the slag outlet of the fuming furnace is opened to discharge slag, a certain thickness of bottom slag is left. This bottom slag is mixed with high-temperature slag of approximately 1300°C produced by a Kifset furnace. During the feeding stage, the slag is fed rapidly for 10 minutes to the maximum reduction coal feed rate. After entering the reduction stage, oxygen is introduced into the secondary air of the fuming furnace to form an oxygen-rich state, ensuring the activity of the high-temperature slag in the fuming furnace. The slag reduction rate decreases more slowly, further enhancing the reduction effect. The metal content of the tail slag decreases, and the metal recovery rate increases.

Description

Technical Field

[0001] This invention relates to the field of reduction blowing technology in pyrometallurgical processes, specifically a blowing method for a pyrometallurgical furnace. Background Technology

[0002] The fuming furnace is a supporting system for the Kifset furnace direct lead smelting process. It employs a continuous slag feeding and continuous blowing operation mode to recover lead and zinc metals from the slag. The fuming process is essentially a reduction and volatilization process. A mixture of pulverized coal and air is blown into the liquid, high-temperature slag inside the fuming furnace, causing the lead and zinc oxides in the slag to be reduced into lead and zinc vapors. Lead oxides and lead sulfides with higher vapor pressures may also volatilize directly in compound form. The metal vapors, metal sulfides, and oxides enter the upper space of the furnace along with the flue gas, where they are re-oxidized into secondary zinc oxide by specially introduced air and collected in a dust collection device for recovery as secondary zinc oxide flue dust products.

[0003] In the prior art, the blowing method of the fuming furnace is as follows: (1) Feeding: High-temperature slag at approximately 1100°C is introduced into the fuming furnace by means of slag chute or steel ladle hoisting; (2) Heating: Turn on the pulverized coal metering device and start blowing pulverized coal into the furnace (oxygen can also be introduced into the secondary air of the fuming furnace at the same time to form an oxygen-rich state) to carry out heating operation, so that the temperature of the high-temperature slag rises to above 1300℃. (3) Reduction: Pulverized coal and air are blown into the fuming furnace (at this time, the secondary air of the fuming furnace stops supplying oxygen) to reduce and volatilize the lead and zinc oxides in the high-temperature slag, and then the zinc oxide dust is oxidized by air. At this time, ensure that the temperature of the high-temperature slag is maintained at 1200-1250℃. (4) Slag discharge: After the processing time is reached, the reduction blowing ends. At this time, the coal feed rate is reduced to 1 / 2 of the reduction coal feed rate. Then, the slag outlet is opened to discharge the high-temperature slag. After the slag discharge is completed, the pulverized coal is stopped and the next feeding is waited for.

[0004] The above-mentioned blowing method requires heating the high-temperature slag to the reduction temperature before increasing the coal feed rate for reduction blowing. During the reduction stage, the slag temperature drops rapidly, and the reduction rate decreases rapidly as a result. Under the same slag processing volume and pulverized coal consumption, the reduction effect is not good, and the metal content of the tailings is basically around 1.2%. Summary of the Invention

[0005] This invention discloses a smelting method for a fuming furnace. When the slag outlet of the fuming furnace is opened to discharge slag, a certain thickness of bottom slag is left. This bottom slag is mixed with high-temperature slag of approximately 1300°C produced by a Kifset furnace. During the feeding stage, the slag is fed rapidly for 10 minutes to the maximum reduction coal feed rate. After entering the reduction stage, oxygen is introduced into the secondary air of the fuming furnace to form an oxygen-rich state, ensuring the activity of the high-temperature slag in the fuming furnace. The slag reduction rate decreases more slowly, further enhancing the reduction effect. The metal content of the tail slag decreases, and the metal recovery rate increases.

[0006] A method for blowing in a fuming furnace, characterized in that: the method for blowing in the fuming furnace is specifically as follows: (1) Feeding: The high-temperature slag produced by the Kifset furnace at about 1300°C is introduced into the fuming furnace through the slag chute. At this time, a certain thickness of bottom slag is left in the fuming furnace. When feeding, the maximum reduction coal feed rate is reached by "rapid coal feeding every 10 minutes".

[0007] (2) Reduction: Pulverized coal is continuously blown into the fuming furnace at the highest reduction coal feed rate. At the same time, oxygen is introduced into the secondary air of the fuming furnace to form an oxygen-rich state, so that the lead and zinc oxides in the high-temperature slag are reduced and volatilized, and then oxidized by air into secondary zinc oxide dust.

[0008] (3) Slag discharge: After the processing time is reached, the reduction blowing ends. At this time, the coal feed rate is reduced to 1 / 3 of the maximum reduction coal feed rate, and oxygen is stopped from being introduced into the secondary air of the fuming furnace. Then, the slag outlet is opened to discharge the high-temperature slag and leave a certain thickness of bottom slag, waiting for the next feeding.

[0009] The processing time of the above-mentioned fuming furnace blowing method is determined by the first furnace, and the endpoint of the determination is that the total content of lead and zinc in the slag is ≤1%.

[0010] In the above-mentioned fuming furnace blowing method, "10-minute rapid coal feeding" means that the coal feeding rate increases by 0.5t / h for every minute of feeding until the maximum reduction coal feeding rate is reached; the oxygen enrichment rate of the secondary air oxygen-enriched state in the reduction stage of the fuming furnace is 23%.

[0011] Advantages of this invention: 1. This invention allows for rapid coal feeding at the beginning of the fuming furnace feeding period, up to the maximum reduction coal feed rate within 10 minutes, quickly entering the reduction state and effectively extending the reduction time under the same blowing cycle.

[0012] 2. In this invention, after the fuming furnace enters the reduction period, oxygen is introduced into the secondary air of the fuming furnace to form an oxygen-rich state, which ensures the activity of the high-temperature slag in the fuming furnace, slows down the decrease in the slag reduction rate, and further enhances the reduction effect.

[0013] 3. When the slag processing volume and pulverized coal consumption are the same in the same blowing cycle of the fuming furnace, the present invention uses the above two measures to reduce the metal content of the tailings and increase the metal recovery rate, which generates huge economic benefits for enterprises. Attached Figure Description

[0014] Figure 1 To illustrate the background technology, a flowchart of the refining process is provided. Figure 2 This is a flowchart of the reduction blowing method of Embodiment 1 of the present invention; Figure 3 This is a schematic diagram of "10-minute rapid coal feeding" in Embodiment 1 of the present invention; Figure 4 This is a schematic diagram of uniform coal feeding in the background technology. Detailed Implementation

[0015] The present invention will be further described in detail below through embodiments, but the scope of the present invention is not limited to these embodiments. Example 1

[0016] A method for blowing in a fuming furnace, wherein the specific method is as follows: (1) Feeding: The high-temperature slag produced by the Kifset furnace at about 1300°C is introduced into the fuming furnace through the slag chute. At this time, a certain thickness of bottom slag is left in the fuming furnace. When feeding, the maximum reduction coal feed rate is reached by "rapid coal feeding every 10 minutes".

[0017] (2) Reduction: Pulverized coal is continuously blown into the fuming furnace at the highest reduction coal feed rate. At the same time, oxygen is introduced into the secondary air of the fuming furnace to form an oxygen-rich state, so that the lead and zinc oxides in the high-temperature slag are reduced and volatilized, and then oxidized by air into secondary zinc oxide dust.

[0018] (3) Slag discharge: After the processing time is reached, the reduction blowing ends. At this time, the coal feed rate is reduced to 1 / 3 of the maximum reduction coal feed rate, and oxygen is stopped from being introduced into the secondary air of the fuming furnace. Then, the slag outlet is opened to discharge the high-temperature slag and leave a certain thickness of bottom slag, waiting for the next feeding.

[0019] In our actual production, the high-temperature slag fed into each furnace is approximately 60 tons, the bottom ash remaining in the fuming furnace is approximately 9 tons, and the air injection rate is 26,000 Nm. 3 The maximum reduction coal feed rate is 7.5 t / h, the pulverized coal consumption per furnace is 12 t, and the number of furnaces per day is 13. Compared with the prior art reduction blowing method, the above embodiment can reduce the metal content of the fuming furnace tail slag by 0.2-0.3%.

[0020] In conclusion, the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for smelting in a fuming furnace, characterized in that: The specific method for blowing in the fuming furnace is as follows: (1) Feeding: The high-temperature slag produced by the Kifset furnace at about 1300°C is introduced into the fuming furnace through the slag chute. At this time, a certain thickness of bottom slag is left in the fuming furnace. When feeding, the maximum reduction coal feed rate is reached by "rapid coal feeding every 10 minutes". (2) Reduction: Pulverized coal is continuously blown into the fuming furnace at the highest reduction coal feed rate. At the same time, oxygen is introduced into the secondary air of the fuming furnace to form an oxygen-rich state, so that the lead and zinc oxides in the high-temperature slag are reduced and volatilized, and then oxidized by air into secondary zinc oxide dust. (3) Slag discharge: After the processing time is reached, the reduction blowing ends. At this time, the coal feed rate is reduced to 1 / 3 of the maximum reduction coal feed rate, and oxygen is stopped from being introduced into the secondary air of the fuming furnace. Then, the slag outlet is opened to discharge the high-temperature slag and leave a certain thickness of bottom slag, waiting for the next feeding.

2. The smelting method in a fuming furnace according to claim 1, characterized in that: (1) "10-minute rapid coal feeding" means that the coal feeding rate increases by 0.5t / h for every minute of feeding until the maximum reduction coal feeding rate is reached; (2) The oxygen enrichment rate of the secondary air in the reduction stage of the fuming furnace is 23%.

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