Weakly acidic furnace slag as well as preparation method and use method thereof

Abstract

The invention relates to a weakly acidic slag charge, a preparation method and a use method, the slag charge mainly comprises the following components in percentage by weight: 92-95% of coal slime, 1.5-3.5% of manganese ore ash and 3-5% of alkaline sintered ore ash. The preparation method mainly comprises the steps of material preparation, fermentation, air drying, crushing and the like. The method comprises the following steps: mixing the raw materials in proportion, adding 50-70% of the coal slime into a fermentation tank containing a proper amount of water, adding all the alkaline sinter, the residual coal slime and the manganese ore ash, uniformly stirring, and fermenting at normal temperature until the pH value reaches 6.1-6.7 to obtain the slag material. And air-drying the furnace slag until the water content is 7.9-9.8%, and finally crushing the furnace slag until the particle size is 10-20mm. After the slag charge is used, the acid-base balance degree of the slag is maintained, the slag amount is slightly increased, stable operation of the blast furnace is facilitated, accumulation of alkali metal in a hearth area can be effectively reduced, the hearth is remarkably protected, and the service life of the blast furnace is prolonged.

Description

Technical Field

[0001] The invention belongs to the technical field of blast furnace ironmaking technology, and in particular relates to a weakly acidic slag material, a preparation method and a use method. Background Art

[0002] In the blast furnace ironmaking process, the lining is a key component that protects the blast furnace body and maintains the high temperature and high pressure environment in the furnace. Its stability and durability directly affect the operating efficiency and life of the blast furnace. However, in actual production, the blast furnace lining is often severely eroded due to a variety of factors, among which alkali metal corrosion is one of the important reasons for the early overhaul of the lining.

[0003] In recent years, with the increasing trend of large-scale blast furnaces, higher requirements have been placed on the corrosion resistance of blast furnace linings. The phenomenon of alkali metals (such as potassium, sodium, etc.) circulating and enriching in blast furnaces is difficult to avoid. These alkali metals react with furnace materials, coke, etc. at high temperatures to generate destructive compounds that corrode the lining materials. Especially in the hearth area, due to the dual effects of molten iron scouring and alkali metals, the lining erosion is more serious, often leading to premature overhaul of the blast furnace, causing huge economic losses to the company.

[0004] In the prior art, the alkali metal corrosion problem of blast furnace lining is mainly solved by controlling the alkali load of the raw materials entering the furnace and improving the alkali removal capacity of the slag. However, due to the influence of various factors such as fluctuations in raw material composition and changes in the atmosphere in the furnace, these measures have limited effects in practical applications and are difficult to fundamentally solve the alkali metal corrosion problem of the blast furnace lining.

[0005] In addition, with the enhancement of environmental awareness and the popularization of the concept of resource recycling, how to turn waste into treasure and convert waste in the blast furnace production process into valuable resources has become a new direction for the development of blast furnace ironmaking technology. Therefore, the development of a blast furnace lining protection technology that can effectively reduce alkali metal corrosion, extend the service life of the blast furnace, and achieve resource recycling has important practical significance and application value. Summary of the invention

[0006] In view of the problems existing in the prior art, the present invention provides a weakly acidic slag material for protecting blast furnace lining from alkali metal corrosion and recycling resources, a preparation method and a use method thereof.

[0007] The present invention is implemented in this way. A weakly acidic slag material is characterized by comprising coal slime, manganese ore ash and alkaline sintered ore ash. According to weight percentage, the coal slime accounts for 92-95%; the manganese ore ash accounts for 1.5-3.5; and the alkaline sintered ore ash accounts for 3-5%.

[0008] Further preferably, the coal slime is selected from coal slime having a content of particles smaller than 200 meshes of about 75% to 85%, and the coal slime is weakly acidic, and its pH value is between 6-8.

[0009] Further preferably, the coal slime contains coal slime with a silicon dioxide content higher than alumina.

[0010] Further preferably, the manganese ore ash has a particle size of less than 5 mm and is in the form of granules or powder.

[0011] Further preferably, the manganese content in the manganese ore ash is greater than 30%, and the ratio of phosphorus to manganese in the manganese ore ash is less than 0.5%.

[0012] Further preferably, the basic sintered ash is high-basicity sintered ash with a basicity of 1.9 or more and a particle size of 5 mm or less.

[0013] The present invention also discloses a method for preparing the weakly acidic slag material, which comprises the following preparation process:

[0014] S1. Material preparation: Take the raw materials according to the following weight proportions, wherein the coal slime accounts for 92-95%, the manganese ore ash accounts for 1.5-3.5% and the basic sintered ash accounts for 3-5% for standby;

[0015] S2, add 50% to 70% of the coal slime into the fermentation tank, the water content in the fermentation tank covers 20cm of water above the material; then add all the alkaline sintered ore, then add the remaining coal slime, and finally add manganese ore ash;

[0016] S3, start the stirring equipment of the fermentation tank, stir evenly, ferment for a certain period of time at room temperature, and measure the pH value between 6.1 and 6.7;

[0017] Stop fermentation, discharge the upper solution after precipitation, and obtain slag material;

[0018] S4, air-drying the slag material at room temperature to make its moisture content between 7.9% and 9.8%;

[0019] S5. The air-dried slag material is crushed to a particle size of 10 to 20 mm, and a weakly acidic slag material is finally obtained.

[0020] Based on the method for using the weakly acidic slag material prepared above, the crushed slag material is conveyed to the coal injection inlet of the blast furnace through a belt, mixed with coal powder and sprayed into the blast furnace.

[0021] The method of using the above-mentioned weakly acidic slag material is as follows: due to the addition of the slag material, the coal powder injection amount is reduced from the normal injection amount of 50 tons / hour, and the coal powder supply amount is reduced to N, 45<N≤48, wherein N is the coal powder supply amount per hour, unit t / hour; the slag material supply amount M is 50-N; at this time, it does not affect the normal supply air volume, and the normal supply air volume is 3900m3 / min.

[0022] The above-mentioned weakly acidic slag material is used in a method where the pulverized coal injection rate is reduced from the normal 50 tons / hour to 45 tons / hour when the slag material is added, and the air intake rate is reduced from 3900m 3 / min adjusted to 4020m 3 / min.

[0023] The invention has the advantages and technical effects: the weakly acidic slag material made of coal slime, manganese ore ash and alkaline sintered ore is used, and its technical effect is remarkable. The slag material produces organic components through the fermentation process, plays a chemical catalytic role, promotes the increase of chemical heat and enthalpy change, effectively feeds back the loss of physical heat, and thus stabilizes the quality requirements of pig iron for steelmaking. At the same time, the weakly acidic environment is more conducive to fungal fermentation, and the obtained large molecular weight organisms further promote the chemical exothermic reaction and improve the smelting efficiency. After using the slag material, the original acid-base balance of the slag is not broken, and the slag volume is measured to increase by about 2% to 4% compared with when it is not used, which helps to maintain the stable operation of the blast furnace. More importantly, through the use of alkali-discharging slag, the technology can effectively reduce the accumulation of alkali metals in the furnace area, reduce the alkali metal content in stages, play a significant protective role on the furnace, and help to extend the service life of the blast furnace. In addition, the preparation process of the slag material makes full use of industrial wastes such as coal slime, manganese ore ash and alkaline sintered ore, realizing the recycling of resources, which not only reduces production costs, but also reduces environmental pollution, reflecting good environmental benefits. In summary, the technology of using this weakly acidic slag material has shown significant advantages in improving smelting efficiency, stabilizing pig iron quality, maintaining the operation status of blast furnaces, extending the life of blast furnaces, and realizing the resource utilization of industrial wastes, providing a new technical approach for the optimization and sustainable development of blast furnace ironmaking processes. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0025] A weakly acidic slag material, characterized in that it comprises coal slime, manganese ore ash and alkaline sintered ore ash, wherein, by weight percentage, the coal slime accounts for 92-95%, the manganese ore ash accounts for 1.5-3.5%, and the alkaline sintered ore ash accounts for 3-5%.

[0026] Preferably, the coal slime is selected from coal slime with a content of particles smaller than 200 mesh accounting for about 75% to 85%, and the coal slime is weakly acidic with a pH value between 6 and 8.

[0027] Preferably, the coal slime contains coal slime with a silicon dioxide content higher than alumina.

[0028] Preferably, the manganese ore ash has a particle size of less than 5 mm and is in the form of granules or powder.

[0029] Preferably, the manganese content in the manganese ore ash is greater than 30%, and the ratio of phosphorus to manganese in the manganese ore ash is less than 0.5%.

[0030] Preferably, the alkaline sintered ash is high-basicity sintered ash with a basicity of 1.9 or more and a particle size of 5 mm or less.

[0031] Comparative experiment was carried out according to weight percentage:

[0032] Material combination ratio Slime Manganese ore ash Basic sintered ash Ph value Add ratio 1 95 1.5 3 6.5 Addition ratio 2 93 2.5 3.5 6.7 Addition ratio 3 92 3.5 4.5 6.8

[0033] The method for preparing the above-mentioned weakly acidic slag material comprises the following preparation process:

[0034] S1. Material preparation: Take the raw materials according to the following weight proportions, wherein the coal slime accounts for 92-95%, the manganese ore ash accounts for 1.5-3.5% and the basic sintered ash accounts for 3-5% for standby;

[0035] S2, add 50% to 70% of the coal slime into the fermentation tank, the water content in the fermentation tank covers 20cm of water above the material; then add all the alkaline sintered ore, then add the remaining coal slime, and finally add manganese ore ash;

[0036] S3, start the stirring equipment of the fermentation tank, stir evenly, ferment for a certain period of time at room temperature, and measure the pH value between 6.1 and 6.7;

[0037] Stop fermentation, discharge the upper solution after precipitation, and obtain slag material;

[0038] S4, air-drying the slag material at room temperature to make its moisture content between 7.9% and 9.8%;

[0039] S5. The air-dried slag material is crushed to a particle size of 10 to 20 mm, and a weakly acidic slag material is finally obtained.

[0040] Based on the method for using the weakly acidic slag material prepared above, the crushed slag material is conveyed to the coal injection inlet of the blast furnace through a belt, mixed with coal powder and sprayed into the blast furnace.

[0041] The above-mentioned weakly acidic slag material usage method, due to the addition of slag material, the coal powder injection amount is reduced from the normal injection amount of 50 tons / hour, and the coal powder supply amount is reduced to N, 45<N≤48, where N is the coal powder supply amount per hour, unit t / hour; the slag material supply amount M is 50-N; at this time, it does not affect the normal supply air volume, and the normal supply air volume is 3900m3 / min. The above-mentioned weakly acidic slag material usage method, when the slag material is added to reduce the coal powder injection amount from the normal injection amount of 50 tons / hour to 45 tons / hour, the air intake volume is 3900m 3 / min adjusted to 4020m 3 / min.

[0042] By comparing the slag components of the slag without alkali removal and the slag with alkali removal, the alkaline oxides in the latter are significantly higher than those in the former.

[0043] Test 1:

[0044] Soda slag Usage (hours) <![CDATA[K2O(%)]]> <![CDATA[Na2O(%)]]> <![CDATA[K2O+Na2O]]> Use the residue ingredients 3 tons 0.47 0.51 0.98 No slag components used 0.41 0.44 0.85

[0045] Test 2:

[0046] Soda slag Usage (hours) <![CDATA[K2O(%)]]> <![CDATA[Na2O(%)]]> <![CDATA[K2O+Na2O]]> Use the residue ingredients 5 tons 0.53 0.57 1.1 No slag components used 0.41 0.44 0.85

[0047] This type of slag can effectively increase the amount of alkali metal discharged from the furnace and reduce the erosion of alkali metal on the furnace lining. Through the use of observation test 1, the test results of the alkaline harmful elements in the slag increased significantly. The amount of slag increased significantly after 2 to 3 hours of use, indicating that the slag material quickly merged with the original slag in the high-temperature area of ​​the tuyere. At the same time, we increased the amount of slag and brought out an increase in the content of alkali metals, and the amount of slag also increased. It was observed that there was no abnormal change in the various indicators of the furnace condition. In this case, it was 1780m 3 Blast furnace, initial air volume 3900m 3 / hour, in test 2, after 4 hours of use, the physical heat of molten iron was measured to be reduced from 1507℃ to 1503℃, and it was further used for 4 hours, so the air volume was increased to 4020m3 / hour until the test was completed without any abnormal situation. Based on the above findings, the slag is easy to slag quickly, merge with the slag, increase the fluidity of the slag, avoid the regional enrichment of alkali metals, bring out more harmful elements, and play a role in discharging them out of the furnace. This slag also promotes the reduction of sulfur and zinc in the furnace.

[0048] 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 and improvements made within the spirit and principles of the present invention, such as adding fluxing materials, coke ash, limestone powder, dolomite powder and other adjustments, should be included in the protection scope of the present invention.

Claims

1. A weakly acidic slag material, characterized in that: It includes coal slime, manganese ore ash and alkaline sintered ore ash. According to weight percentage, the coal slime accounts for 92-95%; the manganese ore ash accounts for 1.5-3.5; and the alkaline sintered ore ash accounts for 3-5%.

2. The weakly acidic slag material according to claim 1, characterized in that: The coal slime is selected from coal slime with a particle content of about 75% to 85% of particles smaller than 200 meshes. The coal slime is weakly acidic and has a pH value between 6 and 8.

3. The weakly acidic slag material according to claim 2, characterized in that: The coal slime contains coal slime whose silicon dioxide content is higher than that of aluminum oxide.

4. The weakly acidic slag material according to claim 1, characterized in that: The manganese ore ash has a particle size of less than 5 mm and powder.

5. The weakly acidic slag material according to claim 1, characterized in that: The manganese content in the manganese ore ash is greater than 30%, and the ratio of phosphorus to manganese in the manganese ore ash is less than 0.5%.

6. The weakly acidic slag material according to claim 2, characterized in that: The alkaline sintered ash is selected from high-alkalinity sintered ash with a basicity of more than 1.9 and a particle size of less than 5 mm.

7. The method for producing the weakly acidic slag material according to any one of claims 1 to 6, characterized in that: The production process includes the following: S1. Material preparation: Take the raw materials according to the following weight proportions, wherein the coal slime accounts for 92-95%, the manganese ore ash accounts for 1.5-3.5% and the basic sintered ash accounts for 3-5% for standby; S2, add 50% to 70% of the coal slime into the fermentation tank, the water content in the fermentation tank covers 20cm of water above the material; then add all the alkaline sintered ore, then add the remaining coal slime, and finally add manganese ore ash; S3, start the stirring equipment of the fermentation tank, stir evenly, ferment for a certain period of time at room temperature, and measure the pH value between 6.1 and 6.7; Stop fermentation, discharge the upper solution after precipitation, and obtain slag material; S4, air-drying the slag material at room temperature to make its moisture content between 7.9% and 9.8%; S5. The air-dried slag material is crushed to a particle size of 10 to 20 mm, and a weakly acidic slag material is finally obtained.

8. A method for using the weakly acidic slag material prepared according to claim 7, characterized in that: The crushed slag material is conveyed to the coal injection inlet of the blast furnace by a belt, mixed with coal powder and sprayed into the blast furnace.

9. The method for using the weakly acidic slag material according to claim 8, characterized in that: Due to the addition of slag, the coal powder injection amount is reduced from the normal injection amount of 50 tons / hour, and the coal powder supply is reduced to N, 45<N≤48, where N is the coal powder supply amount per hour, unit t / hour; the slag material supply amount M is 50-N; at this time, it does not affect the normal supply air volume, and the normal supply air volume is 3900m3 / min.

10. The method for using the weakly acidic slag material according to claim 8, characterized in that: When slag is added, the pulverized coal injection rate is reduced from the normal 50 tons / hour to 45 tons / hour, and the air intake volume is reduced from 3900m 3 / min adjusted to 4020m 3 / min.