A smelting method of hot slag side-blowing reduction furnace

Abstract

The present invention relates to a smelting method of a hot slag side-blown reduction furnace, and belongs to the technical field of lead smelting. In the process of putting raw materials into the reduction furnace, by continuously adding crushed coal and generating foam slag on the molten pool, by controlling the amount of crushed coal added, the height of the foam slag is controlled, the molten pool height and the slag volume are raised, the penetration speed of CO gas generated by carbon and metal oxides in the molten pool is prolonged, and the penetration speed of high-temperature gas generated by natural gas combustion in the molten pool is also prolonged, the fuel utilization efficiency and the heat transfer efficiency of the molten pool are increased, the temperature increase speed is increased, the smelting cycle is shortened, the bed capacity of the side-blown reduction furnace is improved, and the comprehensive energy consumption of lead smelting is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of lead smelting, and in particular relates to a smelting method of a hot slag side-blown reduction furnace. Background Art

[0002] The reduction furnace process belongs to molten pool smelting. The feeding methods include hot materials and cold materials. The hot material is the lead-rich slag produced by the Isa furnace, and the cold material is the cold lead-rich slag, solvent, and reducing agent. The hot material enters the hot material port of the reduction furnace through the Isa furnace slag tank, undergoes a reduction reaction in the furnace, and produces crude lead. The entire reaction tends to be a reduction reaction. The reaction process will cause the temperature of the molten pool to decrease. When the temperature of the molten pool is too low, the slag temperature will be too low. The natural gas combustion gas and the gas produced by the reduction reaction cannot be released normally, causing the molten pool to rise. After rising to a certain extent, during the stirring of the molten pool, the low-temperature slag flows to the arc precipitation area and accumulates too much, causing a large amount of foam slag to be generated around the inclined cover of the reduction furnace. The foam slag overflows from the slag exploration port and around the inclined cover. When the foam slag is generated, it is easy to get out of control if it is not handled properly, causing serious safety and environmental problems.

[0003] To avoid safety issues, the original process cannot produce foamy slag, and only diced coke can be used as a solid reducing agent. The reaction speed of diced coke is slow, and there is no foamy slag in the entire molten pool, which reduces the contact area between metals such as lead and silver in the slag and the reducing agent. If a large amount of diced coke is added to increase the contact area, it will cause excessive addition of diced coke, affecting the slag discharge and slag heating time, extending the smelting cycle, and affecting the bed capacity of the metallurgical furnace and the energy consumption of lead metal products in the molten pool smelting process. Summary of the invention

[0004] In order to solve the above problems, the present invention proposes a smelting method of a hot slag side-blown reduction furnace, which effectively shortens the lead smelting cycle, improves the bed capacity of the side-blown reduction furnace, and reduces the comprehensive energy consumption of lead smelting from 187kgce / t to 128kgce / t.

[0005] To achieve the above object, the present invention is implemented according to the following technical scheme:

[0006] A smelting method of a hot slag side-blown reduction furnace comprises the following steps:

[0007] S1, add 60-80t of hot lead-rich slag into the reduction furnace, and at the same time add 2-3t / h of limestone and 1-1.5t / h of coke into the hot slag side-blowing reduction furnace through the DCS control system; the lead liquid level at the siphon port rises continuously, and when it reaches the flow height of the lead liquid at the siphon port, lead is discharged from the siphon port, and the lead liquid is put into the crude lead ingot casting machine for ingot casting;

[0008] S2, during the material addition process, crushed coal is continuously added through the DCS control system to form foam slag in the molten pool, and the height of the foam slag in the molten pool is controlled to be maintained at 0.3-0.5m by controlling the amount of crushed coal added;

[0009] S3, after all the hot lead-rich slag is added to the reduction furnace, the temperature in the furnace is controlled at 950-1200°C for continuous smelting, and the height of the foam slag in the molten pool is maintained at 0.3-0.5m;

[0010] S4. With the progress of the reduction reaction, the slag temperature gradually decreases. The lead content of the slag is observed through the slag probe. If the lead content of the slag is below 2.2%, and the height of the foam slag in the molten pool is maintained at 0.3-0.5m; after the temperature is raised for 0.5h, the slag discharge operation is carried out.

[0011] Preferably, in step S1, the natural gas flow rate of the reduction furnace is controlled at 250-300 Nm3 / h, the oxygen flow rate is controlled at 750-900 Nm3 / h, the compressed air flow rate is controlled at 600-800 Nm3 / h, the molten pool temperature is controlled at 950-1200°C, and the negative pressure in the furnace is controlled at -20--40 Pa.

[0012] Preferably, the Si:Fe ratio in the hot lead-rich slag is 0.8 to 1.0.

[0013] Preferably, in step S2, the amount of crushed coal added is 0.5-1.2 t / h.

[0014] Preferably, in step S3, the amount of crushed coal added is 1.5-2.5 t / h.

[0015] Preferably, in step S4, the amount of crushed coal added is 0.3-0.6 t / h.

[0016] Preferably, the particle size of the crushed coal is 100 to 300 mm.

[0017] Beneficial effects of the present invention:

[0018] In the process of feeding raw materials into the reduction furnace, the present invention continuously adds crushed coal and generates foamy slag on the molten pool. By controlling the amount of crushed coal added, the height of the foamy slag is controlled, the height of the molten pool and the volume of the slag are raised, the penetration speed of CO gas generated by carbon and metal oxides in the molten pool is prolonged, and the penetration speed of high-temperature gas generated by natural gas combustion in the molten pool is also prolonged, thereby increasing the fuel utilization efficiency and the heat transfer efficiency of the molten pool, increasing the heating speed, shortening the smelting cycle, improving the bed capacity of the side-blown reduction furnace, and reducing the comprehensive energy consumption of lead smelting. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. It is obvious that the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0020] Figure 1 It is a process flow chart of the present invention; DETAILED DESCRIPTION

[0021] In order to make the objectives, technical solutions and beneficial effects of the present invention more clear, the preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings to facilitate understanding by technicians.

[0022] Principle of foam slag height adjustment: The reduction furnace is heated by natural gas, and the natural gas heating in the furnace is quantitative. During the reaction process, crushed coal is continuously added. The reaction speed of crushed coal is fast. The reduction endothermic reaction of crushed coal can quickly reduce the temperature of the molten pool. By controlling the amount of crushed coal added, the temperature in the molten pool can be kept stable at the required temperature, so that a certain amount of foam slag is generated on the molten pool. At the same time, the reaction generates a large amount of CO and CO2 in the molten slag, which increases the height of the foam slag.

[0023] Example:

[0024] 60t of hot lead-rich slag is added to the reduction furnace, 2t / h of limestone and 1t / h of crushed coal are added to the hot slag side-blowing reduction furnace through the DCS control system; the natural gas flow rate of the reduction furnace is controlled at 250Nm 3 / h, oxygen flow control 750Nm 3 / h, compressed air 600Nm 3 / h, the molten pool temperature is controlled at 950℃, and the negative pressure in the furnace is controlled at -20pa; during the material adding process, the amount of crushed coal added is continuously adjusted to control the height of the foam slag in the molten pool to 0.3-0.5m, and the lead liquid level at the siphon port continues to rise. After reaching the flow height of the lead liquid at the siphon port, lead is discharged from the siphon port, and the lead liquid is put into the crude lead ingot casting machine for ingot casting; after all the hot lead-rich slag is added to the reduction furnace, the temperature in the furnace is controlled at 950℃ for continuous smelting, and 1.5t / h of crushed coal is continuously added at the same time; as the reduction reaction proceeds, the slag temperature gradually decreases, and the lead content in the slag is observed by the slag probe. If the lead content in the slag is below 2.2%, the amount of crushed coal is reduced to 0.3t / h, and the temperature is raised for 0.5h; slag discharge operation is carried out.

[0025] Comparison table of raw material consumption at different foam slag heights

[0026]

[0027] Preferably, the Si:Fe ratio in the hot lead-rich slag is 0.8-1.0, which reduces the Fe3O4 content in the slag, avoids a rapid increase in the viscosity of the slag, allows the gas fed into the molten pool and the gas generated by the reaction to be released in time, and effectively avoids the generation of severe foamy slag.

[0028] Comparative Example: (the process of adding materials and smelting in the original process, and using coke as the solid reducing agent)

[0029] 60t of hot lead-rich slag is added to the reduction furnace, and at the same time, 1.5t / h of limestone, 3t / h of iron roasted sand, 2t / h of coke and 0.8t / h of crushed coal are added to the hot slag side-blown reduction furnace through the DCS control system; during the addition of hot lead-rich slag, the lead liquid level at the siphon port continues to rise, and when it reaches the flow height of the lead liquid at the siphon port, lead is released from the siphon port, and the lead liquid is put into the crude lead ingot casting machine for ingot casting; 2.2t of limestone, 3t of iron roasted sand, 2t of coke and 2.5t of crushed coal are added to each furnace; the gas flow rate is controlled at 3200~3600Nm 3 / h, oxygen flow rate is controlled at 950~1200Nm 3 / h, the molten pool temperature is controlled within 1100 ~ 1300 ℃, and the negative pressure in the furnace is controlled at -20 ~

[0030] -40pa; after all the hot lead-rich slag is added into the reduction furnace, crushed coal is continuously added for smelting at a temperature of 1000-1250°C for 1-2h. As the reduction reaction proceeds, the slag temperature gradually decreases. The lead content in the slag is observed by a slag probe. If the lead content in the slag is below 2.2%, the amount of crushed coal is reduced. After the temperature is raised for 0.5h, the slag discharge operation is carried out.

[0031] Comparison table of different process capabilities

[0032] Bed capacity t / m2.d Comprehensive energy consumption of lead smelting Smelting cycle Comparative Example 39.8 187kgce / t 4.5h Example 50.6 128kgce / t 3.5h

[0033] It can be seen from the above table that in the current smelting process, the smelting performance has been improved, the smelting cycle has been effectively shortened, and the smelting cost has been reduced.

[0034] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made in form and details without departing from the scope defined by the claims of the present invention; the dimensions of the drawings are independent of the specific objects, and the dimensions of the objects can be changed arbitrarily.

Claims

1. A smelting method of a hot slag side-blown reduction furnace, characterized in that: The specific steps include: S1, add 60-80t of hot lead-rich slag into the reduction furnace, and at the same time add 2-3t / h of limestone and 1-1.5t / h of coke into the hot slag side-blowing reduction furnace through the DCS control system; the lead liquid level at the siphon port rises continuously, and when it reaches the flow height of the lead liquid at the siphon port, lead is discharged from the siphon port, and the lead liquid is put into the crude lead ingot casting machine for ingot casting; S2, during the material addition process, crushed coal is continuously added through the DCS control system, the amount of crushed coal added is 0.5-1.2t / h, foam slag is formed in the molten pool, and the height of the foam slag in the molten pool is controlled to be maintained at 0.3-0.5m by controlling the amount of crushed coal added; S3, after all the hot lead-rich slag is added to the reduction furnace, the temperature in the furnace is controlled at 950-1200°C for continuous smelting, the amount of crushed coal added is 1.5-2.5t / h, and the height of the foam slag in the molten pool is maintained at 0.3-0.5m; S4. As the reduction reaction proceeds, the slag temperature gradually decreases. The lead content in the slag is observed through the slag probe. If the lead content in the slag is below 2.2%, the amount of crushed coal added is 0.3-0.6t / h, and the height of the foam slag in the molten pool is maintained at 0.3-0.5m; after the temperature is raised for 0.5h, the slag discharge operation is carried out.

2. The smelting method of a hot slag side-blown reduction furnace according to claim 1, characterized in that: In step S1, the natural gas flow rate of the reduction furnace is controlled at 250-300Nm3 / h, the oxygen flow rate is controlled at 750-900Nm3 / h, the compressed air flow rate is controlled at 600-800Nm3 / h, the molten pool temperature is controlled at 950-1200℃, and the negative pressure in the furnace is controlled at -20--40Pa.

3. The smelting method of a hot slag side-blown reduction furnace according to claim 1, characterized in that: In step S1, the Si:Fe ratio in the hot lead-rich slag is 0.8-1.

0.

4. The smelting method of a hot slag side-blown reduction furnace according to claim 1, characterized in that: The particle size of crushed coal is 100-300mm.

Images