Composite heat preservation process for high-temperature waste steel

Abstract

The invention belongs to the technical field of ferrous metallurgy, and particularly relates to a composite heat preservation process for high-temperature waste steel. The heat preservation process comprises the following steps that a, 20-30 s before preheating of the scrap steel is finished, a layer of mixture of CaO and Al2O3 is spread on the surface of the scrap steel to serve as a heating consolidation heat preservation layer; b, 15-25 s after spreading is finished, the mixture of CaO and Al2O3 is melted and solidified on the surface of the waste steel, and then the mixture of MgO-C and SiC is spread to serve as a radiation heat insulation layer; and c, the tightly-wrapped high-temperature preheated waste steel is loaded into a waste steel tank and transferred to a converter through a waste steel tank car. The heating consolidation heat preservation layer and the radiation heat insulation layer are laid and scattered to conduct heat preservation on the waste steel, and the problem of temperature loss of the waste steel in the conveying and transferring process can be solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of iron and steel metallurgy, and particularly relates to a composite heat preservation process for high-temperature scrap steel. Background Art

[0002] With the increase of the iron and steel accumulation in China, steel enterprises have increased the scrap ratio in the production process. However, the low temperature and high residual elements of scrap steel have greatly limited the increase of the scrap ratio. Therefore, in the research and development of a clean heating process to increase the temperature of scrap steel, how to minimize the temperature loss of scrap steel during the transmission and transfer process has become an urgent need for current steel enterprises.

[0003] Chinese Patent with publication number CN208936788U discloses a scrap steel heating device and the utilization of waste heat from the flue gas of an electric arc furnace. This invention sends the high-temperature flue gas from the top of the electric arc furnace to each area of the scrap steel heating bed through a high-temperature main flue pipe, effectively improving the scrap steel heating effect, ensuring the temperature of the scrap steel discharged from the scrap steel heating bed, improving the smelting effect of the electric arc furnace, and reducing energy consumption; by setting a smoke suction hood at the bottom of the scrap steel heating bed, the flue gas can vertically penetrate the scrap steel layer, improving the heating efficiency and effect of the scrap steel.

[0004] Chinese Patent with publication number CN115572791A discloses an intelligent bucket-type scrap steel heating system. This method is the most direct and obvious way to increase the molten steel production, which can increase the amount of scrap steel added while increasing the temperature of the scrap steel entering the furnace, and at the same time will not extend the process cycle of the converter. It is the most direct and effective way to reduce the molten iron consumption in the steel mill. This process has the advantages of a large amount of scrap steel added and low heat loss.

[0005] The above methods have great limitations. They only simply preheat the scrap steel and do not mention how to minimize the temperature loss of the scrap steel during the transmission and transfer process.

[0006] Therefore, there is an urgent need for a composite heat preservation process for high-temperature scrap steel to solve the problem of serious temperature loss of scrap steel during the transmission and transfer process. Summary of the Invention

[0007] To overcome the defects of the prior art, the technical problem solved by the present invention is to provide a composite heat preservation process for high-temperature scrap steel. The present invention insulates the scrap steel by spreading a heat-generating consolidated heat preservation layer + a radiation heat insulation layer, and can solve the problem of temperature loss of the scrap steel during the transmission and transfer process.

[0008] To achieve the above object, the present invention is realized by adopting the following technical solutions:

[0009] A composite heat preservation process for high-temperature scrap steel, the heat preservation process having the following steps:

[0010] a. 20 - 30 s before the end of the scrap preheating, spread a layer of the mixture of CaO and Al2O3 on the surface of the scrap as the heat - generating consolidation insulation layer;

[0011] b. After 15 - 25 s from the end of spreading, the mixture of CaO and Al2O3 melts and consolidates on the surface of the scrap, and then spread the mixture of MgO - C and SiC as the radiation heat - insulation layer;

[0012] c. Load the well - wrapped high - temperature preheated scrap into the scrap trough and transfer it to the converter by the scrap trough car.

[0013] In the step a, the particle size of the scrap is 20 - 150 mm.

[0014] In the step a, the preheating temperature of the scrap is 400 - 600 °C.

[0015] In the step a, by mass percentage, the ratio of CaO to Al2O3 is 1:(0.44 - 0.65).

[0016] In the step a, the spreading thickness of the CaO and Al2O3 mixture is 2 - 4 cm.

[0017] In the step b, by mass percentage, the ratio of MgO - C to SiC is 1:(0.35 - 0.55).

[0018] In the step b, the spreading thickness of the CaO and Al2O3 mixture is 3 - 5 cm.

[0019] In the step c, quartz sand or lime with a spreading thickness of 3 - 5 cm is evenly spread in advance in the scrap trough car.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] 1) Through the composite heat - insulation process of the radiation heat - insulation layer and the heat - generating consolidation insulation layer, the present invention can reduce the temperature loss of the scrap during the transmission and transfer processes. In addition, the introduced components will not cause a burden on the converter smelting, and have low cost, environmental friendliness and high production efficiency.

[0022] 2) By evenly spreading quartz sand in advance in the scrap trough car, the present invention can further reduce the temperature loss of the scrap during the transmission and transfer processes. Detailed implementation manners

[0023] The following further describes the detailed implementation manners of the present invention:

[0024] Example 1

[0025] The present invention provides a composite heat - insulation process for high - temperature scrap, and the heat - insulation process has the following steps:

[0026] a. 20 s before the end of scrap preheating, spread a layer of CaO and Al2O3 mixture with a thickness of 2 cm on the surface of the scrap as a heat-generating consolidation insulation layer. By mass percentage, the ratio of CaO to Al2O3 is 1:0.44; among them, the particle size of the scrap is 20 mm, and the preheating temperature of the scrap is 400 °C.

[0027] b. 15 s after the spreading is completed, the CaO and Al2O3 mixture melts and consolidates on the surface of the scrap, and then spread a mixture of MgO-C and SiC as a radiation insulation layer. By mass percentage, the ratio of MgO-C to SiC is 1:0.35;

[0028] c. Load the well-wrapped high-temperature preheated scrap into the scrap trough. Uniformly spread quartz sand with a thickness of 3 cm in the scrap trough car in advance, and transfer it to the converter through the scrap trough car.

[0029] Under these process conditions, the temperature loss of the scrap during transmission and transfer is 25 °C.

[0030] Example 2

[0031] The present invention provides a composite insulation process for high-temperature scrap, and the insulation process has the following steps:

[0032] a. 30 s before the end of scrap preheating, spread a layer of CaO and Al2O3 mixture with a thickness of 4 cm on the surface of the scrap as a heat-generating consolidation insulation layer. By mass percentage, the ratio of CaO to Al2O3 is 1:0.65; among them, the particle size of the scrap is 150 mm, and the preheating temperature of the scrap is 600 °C.

[0033] b. 25 s after the spreading is completed, the CaO and Al2O3 mixture melts and consolidates on the surface of the scrap, and then spread a mixture of MgO-C and SiC as a radiation insulation layer. By mass percentage, the ratio of MgO-C to SiC is 1:0.55;

[0034] c. Load the well-wrapped high-temperature preheated scrap into the scrap trough. Uniformly spread quartz sand with a thickness of 5 cm in the scrap trough car in advance, and transfer it to the converter through the scrap trough car.

[0035] Under these process conditions, the temperature loss of the scrap during transmission and transfer is 19 °C.

[0036] Example 3

[0037] The present invention provides a composite insulation process for high-temperature scrap, and the insulation process has the following steps:

[0038] a. 25 s before the end of the scrap preheating, a layer of CaO and Al2O3 mixture with a thickness of 3 cm is spread on the surface of the scrap as a heat-generating consolidation insulation layer. By mass percentage, the ratio of CaO to Al2O3 is 1:0.49. Among them, the particle size of the scrap is 90 mm, and the preheating temperature of the scrap is 500 °C.

[0039] b. 19 s after the spreading is completed, the CaO and Al2O3 mixture melts and consolidates on the surface of the scrap, and then a mixture of MgO-C and SiC is spread as a radiation insulation layer. By mass percentage, the ratio of MgO-C to SiC is 1:0.44.

[0040] c. The well-wrapped high-temperature preheated scrap is loaded into the scrap trough, and lime with a thickness of 4 cm is evenly spread in the scrap trough car in advance, and then it is transported to the converter through the scrap trough car.

[0041] Under these process conditions, the temperature loss of the scrap during transmission and transfer is 23 °C.

[0042] It can be seen from the above that the present invention provides a composite insulation process for high-temperature scrap, which can solve the problem of serious temperature loss of existing scrap during transmission and transfer, will significantly reduce the production cost of steelmaking, and has important engineering application value for the improvement of the metallurgical process flow.

[0043] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, and these simple modifications all belong to the protection scope of the present invention. In addition, it should be noted that, in the above specific embodiments, the various specific technical features described can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the present invention will not separately describe various possible combination methods. In addition, any combination can be made between different embodiments of the present invention as long as it does not violate the idea of the present invention, and it should also be regarded as the content disclosed by the present invention.

Claims

1. A composite heat preservation process for high-temperature scrap steel, characterized in that, The heat preservation process has the following steps: a. 20 - 30 s before the end of the scrap preheating, spread a layer of mixture of CaO and Al2O3 on the surface of the scrap as a heat - generating consolidation heat - preservation layer; b. 15 - 25 s after the spreading is completed, the mixture of CaO and Al2O3 melts and consolidates on the surface of the scrap, and then spread a mixture of MgO - C and SiC as a radiation heat - insulation layer; c. Load the tightly - wrapped high - temperature preheated scrap into the scrap trough and transport it to the converter by the scrap trough car.

2. The composite heat preservation process for high-temperature scrap steel according to claim 1, wherein In step a, the particle size of the scrap is 20 - 150 mm.

3. The composite heat preservation process for high-temperature scrap steel according to claim 1, characterized in that, In step a, the preheating temperature of the scrap is 400 - 600 °C.

4. The composite heat preservation process for high-temperature scrap steel according to claim 1, characterized in that, In step a, by mass percentage, the ratio of CaO to Al2O3 is 1:(0.44 - 0.65).

5. The composite heat preservation process for high-temperature scrap steel according to claim 1, characterized in that In step a, the spreading thickness of the CaO and Al2O3 mixture is 2 - 4 cm.

6. The composite heat preservation process for high-temperature scrap steel according to claim 1, characterized in that In step b, by mass percentage, the ratio of MgO - C to SiC is 1:(0.35 - 0.55).

7. A composite heat preservation process for high-temperature scrap steel according to claim 1, characterized in that, In step b, the spreading thickness of the CaO and Al2O3 mixture is 3 - 5 cm.

8. The composite heat preservation process for high-temperature scrap steel according to claim 1, characterized in that, In step c, quartz sand or lime with a spreading thickness of 3 - 5 cm is evenly spread in advance in the scrap trough car.