A direct reduction smelting process

Abstract

The application develops a direct reduction and blowing process of a fuming furnace, which leaves a certain thickness of bottom slag when the slag port of the fuming furnace is opened to discharge slag, mixes the high-temperature furnace slag of about 1300 DEG C produced by the Kivcet furnace, and directly carries out reduction and blowing by quickly increasing the powder coal blowing amount without a temperature rising step; the process method shortens the treatment cycle when the same amount of furnace slag is treated, and can effectively improve the treatment amount and treatment speed of the fuming furnace.

Description

Technical Field

[0001] This invention relates to the field of reduction blowing technology in pyrometallurgical furnaces, specifically a direct reduction blowing process in 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 products.

[0003] In the existing technology, the reduction blowing process of the fuming furnace is as follows:

[0004] (1) Feeding: High-temperature slag at approximately 1100°C is introduced into the fuming furnace by means of slag chute or steel ladle hoisting;

[0005] (2) Heating: Turn on the pulverized coal metering device and start blowing pulverized coal into the furnace to raise the temperature of the high-temperature slag to 1200-1250℃.

[0006] (3) Reduction: Pulverized coal and air are blown into the fuming furnace to reduce and volatilize the lead and zinc oxides in the high-temperature slag, and then the zinc oxide is oxidized by air. At this time, ensure that the temperature of the high-temperature slag is maintained at 1200-1250℃.

[0007] (4) Slag discharge: After the processing time is reached, the reduction blowing ends. At this time, the amount of pulverized coal is reduced to 1 / 2 of the original amount. 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.

[0008] The aforementioned reduction blowing process requires heating the high-temperature slag to the reduction temperature before pulverized coal is blown in for reduction blowing. This process has a long processing cycle for the same amount of slag, which limits the processing capacity of the fuming furnace. Summary of the Invention

[0009] This invention develops a direct reduction blowing process for a fuming furnace. By leaving a certain thickness of bottom ash when opening the slag outlet of the fuming furnace, and mixing it with high-temperature slag of approximately 1300°C produced by the Kifset furnace, the process can quickly increase the amount of pulverized coal fed in for direct reduction blowing without the need for a heating step. This process shortens the processing cycle for the same amount of slag and can effectively improve the processing capacity and speed of the fuming furnace.

[0010] A direct reduction blowing process in a fuming furnace, the specific details of which are as follows:

[0011] (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.

[0012] (2) Reduction: Pulverized coal and air are continuously blown into the fuming furnace to reduce and volatilize the lead and zinc oxides in the high-temperature slag, and then they are oxidized by air to form secondary zinc oxide. At this time, ensure that the temperature of the high-temperature slag is maintained at 1200-1250℃.

[0013] (3) Slag discharge: After the processing time is reached, the reduction blowing ends. At this time, the amount of pulverized coal is reduced to 1 / 2 of the original amount. 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.

[0014] A direct reduction blowing process in a fuming furnace, the specific details of which are as follows:

[0015] (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.

[0016] (2) Primary reduction: Pulverized coal and air are continuously blown into the fuming furnace to reduce and volatilize the lead and zinc oxides in the high-temperature slag, and then they are oxidized by air into secondary zinc oxide.

[0017] (3) Heating: When the shaking of the fuming furnace body increases, reduce the amount of pulverized coal injected to 1 / 2 of the original amount and carry out heating operation. The heating time is 5-10 minutes.

[0018] (4) Secondary reduction: The continuously injected pulverized coal and air reduce and volatilize the lead and zinc oxides in the high-temperature slag, and then they are oxidized by air into secondary zinc oxide.

[0019] (5) Slag discharge: After the processing time is reached, the reduction blowing ends. At this time, the amount of pulverized coal is reduced to 1 / 2 of the original amount. 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.

[0020] The processing time for the two direct reduction blowing processes in the above-mentioned fuming furnaces was determined for the first furnace, and the endpoint of the determination was that the total lead and zinc content in the slag was ≤1.2%.

[0021] In the two direct reduction blowing processes of the above-mentioned fuming furnace, the mass ratio of the bottom ash remaining in the fuming furnace to the high-temperature slag fed in is 10%-20%.

[0022] The determination of the heating point in step (3) of the above-mentioned second type of direct reduction blowing process of fuming furnace is mainly achieved by observing the shaking of the fuming furnace body: Since the high temperature slag in the fuming furnace is difficult to measure directly by temperature sensor, after the temperature of the liquid high temperature slag drops and becomes viscous, the resistance to the pulverized coal and air blown into the furnace increases, resulting in greater shaking of the fuming furnace body, which is ultimately used as the basis for the heating point.

[0023] Advantages of this invention:

[0024] 1. Since the high-temperature slag produced by our Kifset furnace has a temperature of approximately 1300℃, which is higher than the reduction blowing temperature, a certain thickness of bottom slag is left in the fuming furnace. This allows the fuming furnace to quickly increase the amount of pulverized coal injected after feeding without the need for a heating step, and directly carry out reduction blowing. This process method shortens the processing cycle for the same amount of slag and can effectively improve the processing capacity and speed of the fuming furnace.

[0025] 2. This invention can form two reduction blowing processes: The first is to start reduction blowing directly after feeding, maintaining the temperature of the high-temperature slag during the reduction blowing process until the reduction blowing is completed, and then opening the slag outlet to discharge the slag; The second is to start primary reduction directly after feeding, and when the shaking of the fuming furnace body increases, the amount of pulverized coal injected is reduced to 1 / 2 of the original injection amount and the temperature is increased. After the temperature is increased, a secondary reduction is performed until the secondary reduction is completed, and then the slag outlet is opened to discharge the slag; The above reduction blowing processes can effectively improve the processing capacity and processing speed of the fuming furnace;

[0026] 3. The second type of direct reduction blowing process in the fuming furnace is a supplement to the first type of direct reduction blowing process in the fuming furnace: when the temperature of the liquid high-temperature slag drops and becomes viscous during reduction blowing, the furnace body of the fuming furnace shakes more. At this time, it is necessary to raise the temperature of the fuming furnace, that is, to switch from the first process to the second process. Attached Figure Description

[0027] Figure 1 To illustrate the background technology, a flow chart of the blowing process is provided.

[0028] Figure 2 This is a flow chart of the reduction blowing process in Embodiment 1 of the present invention;

[0029] Figure 3 This is a flow chart of the reduction blowing process in Embodiment 2 of the present invention. Detailed Implementation

[0030] Example 1

[0031] A direct reduction blowing process in a fuming furnace, the specific details of which are as follows:

[0032] (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.

[0033] (2) Reduction: Pulverized coal and air are continuously blown into the fuming furnace to reduce and volatilize the lead and zinc oxides in the high-temperature slag, and then they are oxidized by air to form secondary zinc oxide. At this time, ensure that the temperature of the high-temperature slag is maintained at 1200-1250℃.

[0034] (3) Slag discharge: After the processing time is reached, the reduction blowing ends. At this time, the amount of pulverized coal is reduced to 1 / 2 of the original amount. 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.

[0035] Example 2

[0036] A direct reduction blowing process in a fuming furnace, the specific details of which are as follows:

[0037] (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.

[0038] (2) Primary reduction: Pulverized coal and air are continuously blown into the fuming furnace to reduce and volatilize the lead and zinc oxides in the high-temperature slag, and then they are oxidized by air into secondary zinc oxide.

[0039] (3) Heating: When the shaking of the fuming furnace body increases, reduce the amount of pulverized coal injected to 1 / 2 of the original amount and carry out heating operation. The heating time is 5-10 minutes.

[0040] (4) Secondary reduction: The continuously injected pulverized coal and air reduce and volatilize the lead and zinc oxides in the high-temperature slag, and then they are oxidized by air into secondary zinc oxide.

[0041] (5) Slag discharge: After the processing time is reached, the reduction blowing ends. At this time, the amount of pulverized coal is reduced to 1 / 2 of the original amount. 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.

[0042] 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 24,500 Nm. 3 / h, the pulverized coal injection rate (PV) is 6.5t / h. When a certain batch does not experience significant furnace shaking in the fuming furnace, the method of Example 1 is used directly; when a certain batch experiences significant furnace shaking in the fuming furnace, the method of Example 2 is used.

[0043] In practice, when using the reduction blowing process described in the above embodiments, our company processes 12 furnaces per day. Compared to the prior art reduction blowing process, the above embodiments can increase the throughput of the fuming furnace by 10%-20%.

[0044] 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 direct reduction blowing process in a fuming furnace, characterized in that: The specific details of the direct reduction blowing process in the fuming furnace are as follows: (1) Feeding: The high-temperature slag produced by the Kifset furnace 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. (2) Primary reduction: Pulverized coal and air are continuously blown into the fuming furnace to reduce and volatilize the lead and zinc oxides in the high-temperature slag, and then they are oxidized by air into secondary zinc oxide; (3) Heating: When the shaking of the fuming furnace body increases, reduce the amount of pulverized coal injected to 1 / 2 of the original amount and carry out heating operation. The heating time is 5-10 minutes. (4) Secondary reduction: The continuously injected pulverized coal and air reduce and volatilize the lead and zinc oxides in the high-temperature slag, and then they are oxidized by air into secondary zinc oxide; (5) Slag discharge: After the processing time is reached, the reduction blowing ends. At this time, the amount of pulverized coal is reduced to 1 / 2 of the original amount. 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. The bottom slag left in the fuming furnace: the mass ratio of the high-temperature slag fed is 10%-20%.

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