CN110835677A - A method for improving sintered ore phase structure - Google Patents

Abstract

A method for improving the mineral phase structure of sintered ore, adding an additive to the sintering mixture, and the additive is composed of the following parts by mass: H ₃ BO ₃ 10-20, CaCl ₂ 67-85, NaCl 5-10, KMnO ₄ 1‑3. The present invention designs an additive through in-depth research and repeated tests aimed at improving the quality of sintered ore. Adding the aqueous solution of the additive to the sintering mixture can promote the bonding of Fe3O4 with calcium ferrite and dicalcium silicate to form an interwoven erosion structure during the sintering process, reducing the sintered ore porphyritic structure and increasing the stability of the sintered ore phase. , reduce the formation of dicalcium silicate, and obviously promote the formation of acicular calcium ferrite, increase the uniformity of the sintered ore phase, effectively improve the sintered ore microstructure, and improve the quality of the sintered ore.

Description

A method for improving sintered ore phase structure

technical field

The invention relates to a sintering technology, in particular to a method for improving the mineral phase structure of sintered ore, and belongs to the technical field of iron and steel smelting.

Background technique

Sinter is the main raw material of blast furnace. With the continuous progress and development of the iron and steel industry, the quality requirements for sinter are getting higher and higher. The ore phase composition and microstructure of sinter determine the quality of sinter. At present, the mineral phase composition of high-basicity sintered ore includes: metal phases such as hematite, magnetite, and calcareous fonite, and binder phases such as calcium ferrite, silicate, and glass. Among them, calcium ferrite is an important binder phase for high basicity sintering. Calcium ferrite has good reducibility and compressive strength. The quantity and structure of calcium ferrite in the sinter play a decisive role in the strength and metallurgical properties of the sinter. effect. In addition, dicalcium silicate is also a common binder phase in sinter. Dicalcium silicate includes 4 variants, namely α, α', β, and γ types, but β and γ types usually appear in sinter. Dicalcium silicate, in the process of high temperature sinter cooling, β-type dicalcium silicate will be transformed into γ-type dicalcium silicate, volume expansion, resulting in automatic pulverization of sinter, reducing the strength and quality of sinter. The effective way to improve the quality of sintered ore by adding suitable additives to the sintering mixture is also a key project researched by industry insiders.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a method for improving the mineral phase structure of sintered ore by adding additives in proportion to the sintered material, thereby effectively improving the quantity and structure of calcium ferrite in the sintering ore, and achieving the purpose of improving the quality of the sintering ore.

In order to achieve the above object, the technical scheme adopted in the present invention is as follows:

A method for improving the mineral phase structure of sintered ore, adding an additive to the sintering mixture, the additive is composed of the following parts by mass: H ₃ BO ₃ 10-20, CaCl ₂ 67-85, NaCl 5-10, KMnO ₄ 1-3.

In the above method for improving the mineral phase structure of sintered ore, the amount of additive added is 0.4‰-0.6‰ of the sintering mixture.

In the above-mentioned method for improving the mineral phase structure of sintered ore, the adding method of the additive is as follows: weighing the additive according to the proportion; mixing the additive and water according to the proportioning ratio of the additive and water 1:100, and fully stirring to make the additive solution; During the first mixing process of sintering, all the additives are added to the sintered material and fully mixed, and then the second mixing is performed.

The present invention designs an additive through in-depth research and repeated tests aimed at improving the quality of sintered ore. Adding the aqueous solution of the additive to the sintering mixture can promote the bonding of Fe3O4 with calcium ferrite and dicalcium silicate to form an interwoven erosion structure during the sintering process, reduce the spot-like structure in the sintered ore, and increase the stability of the sintered ore ore phase , reduce the formation of dicalcium silicate, and obviously promote the formation of acicular calcium ferrite, increase the uniformity of the sintered ore phase, effectively improve the sintered ore microstructure, and improve the quality of the sintered ore.

Description of drawings

Figure 1(a) shows the mineral phase of hematite in the sintered ore as it is;

Figure 1(b) shows the mineral phase of the sintered ore as it is with a porphyritic-granular structure;

Figure 1(c) shows the mineral phase of the sintered ore as it is, showing the cemented structure of magnetite and silicate;

Figure 2(a) is a comparative example showing the mineral phase of the eroded structure and the concentrated distribution of calcium ferrite;

Figure 2(b) is a comparative example showing the mineral phase of skeletal hematite;

Fig. 3 (a) shows the mineral phase of concentrated distribution of plate-like and fibrous calcium ferrite in Example 1;

Fig. 3(b) is the mineral phase of hematite showing hematite distribution of hetmorphic-hydrite distribution in Example 1;

Figure 4(a) shows the mineral phase of concentrated acicular and fibrous calcium ferrite in Example 2;

Figure 4(b) shows the mineral phase of Example 2 showing the erosion structure.

Detailed ways

The technical point of the present invention is to add an additive which can effectively improve the quality of sintered ore into the sintering mixture. The components of the additive consist of the following parts by mass: H ₃ BO ₃ 10-20, CaCl ₂ 67-85, NaCl 5-10, KMnO ₄ 1-3. In the additive, H ₃ BO ₃ enters the lattice space lattice of calcium ferrite to form a solid solution under high temperature conditions, which increases the stability of calcium ferrite; the role of CaCl ₂ is to prevent the reduction and pulverization of sinter; Ca element is more active, adding a certain amount of NaCl in the additive is proved to be beneficial to the process of sintering and mineralization;

The role of KMnO ₄ in the additive is: KMnO ₄ is a strong oxidant, which can release oxygen at high temperature, ensure the oxidizing atmosphere in the sintering process, and promote the oxidation of low-price iron oxidation, especially the oxidation of magnetite. This is because Fe3O4 It cannot directly react with CaO to form calcium ferrite. If magnetite cannot be oxidized to hematite, the obtained sinter is mainly composed of magnetite and silicate. The KMnO4 in this additive can ensure that the magnetite is oxidized during the sintering process, and Fe3O4 is oxidized to Fe2O3. The newly oxidized Fe2O3 has a stronger reaction ability with CaO, and will generate more at higher basicity and lower sintering temperature. The acicular calcium ferrite improves the quality of sinter.

Experiments show that KMnO4 can show its effect when the addition amount of KMnO4 exceeds ₁ %, but KMnO4 is a non-ferrous substance, and too much addition will reduce the iron content of the sintered ore. In addition, KMnO4 is a strong oxidant and is relatively expensive. From the perspective of cost and sinter quality, the content of KMnO ₄ is controlled at 3%. Experiments show that the main advantage of the present invention is that it can promote the bonding of Fe3O4 with calcium ferrite and dicalcium silicate to form an interwoven erosion structure during the sintering process, reduce the spot-like structure in the sintered ore, increase the stability of the sintered ore ore phase, and reduce the amount of sintered ore. The formation of dicalcium silicate promotes the formation of acicular calcium ferrite, increases the uniformity of the sintered ore phase, and effectively improves the microstructure of the sintered ore.

The following examples will further illustrate the present invention.

Example 1: Prepare additives according to the following parts by mass: 15 parts of H ₃ BO ₃ , 72 parts of CaCl ₂ , 10 parts of NaCl, 2 parts of KMnO ₄ ; take 0.02 kg of additives and dissolve them in 2 kg of water to make an additive solution; sintered cup test : Use 50kg sintering cup, 40kg sintering mixture, add the prepared additive solution during the first mixing and mix well, and use the drum pelletizing machine for the second mixing. about. In order to prevent the liquid phase adhesion of the grate bars generated during the sintering process, 1kg of sintered ore with a particle size of 10-16mm is placed on the grate bars of the sintering cup before the sintering process begins, and the charging amount of the sintering mixture is controlled at about 40kg. The layer thickness is controlled to 650mm. Using petroleum liquefied gas for sintering ignition, the sintering ignition temperature is controlled to 1100 ℃, the sintering ignition time is 1.5min, the sintering ignition negative pressure is controlled to 8KPa, the negative pressure of sintering and sintering process is controlled to 12KPa, and the sintering waste gas temperature starts to decrease from the highest point. At the end of sintering, the sintering ends when the exhaust gas temperature drops by 150° C. from the highest point, and the sintered ore of Example 1 is prepared.

Example 2: The additives were prepared according to the following parts by mass: 10 parts of H ₃ BO ₃ , 85 parts of CaCl ₂ , 5 parts of NaCl, and 3 parts of KMnO ₄ ; 0.02 kg of additives were dissolved in 2 kg of water to prepare an additive solution; sintered cup test : Use 50kg sintering cup, 40kg sintering mixture, add the prepared additive solution during the first mixing and mix well, and use the drum pelletizing machine for the second mixing. about. In order to prevent the liquid phase adhesion of the grate bars generated during the sintering process, 1kg of sintered ore with a particle size of 10-16mm is placed on the grate bars of the sintering cup before the sintering process begins, and the charging amount of the sintering mixture is controlled at about 40kg. The layer thickness is controlled to 650mm. Using petroleum liquefied gas for sintering ignition, the sintering ignition temperature is controlled at 1100 ℃, the sintering ignition time is 1.5min, the sintering ignition negative pressure is controlled at 8KPa, the sintering and sintering process negative pressure is controlled at 12KPa, and the sintering exhaust gas temperature starts to decrease from the highest point. At the end of sintering, the sintering ends when the exhaust gas temperature drops by 150°C from the highest point, and the sintered ore of Example 2 is prepared.

Example 3: The additives were prepared according to the following parts by mass: 20 parts of H ₃ BO ₃ , 67 parts of CaCl ₂ , 7 parts of NaCl, 1 part of KMnO ₄ ; 0.02 kg of additives were dissolved in 2 kg of water to prepare an additive solution; sintered cup test : Use 50kg sintering cup, 40kg sintering mixture, add the prepared additive solution during the first mixing and mix well, and use a roller ball making machine for the second mixing. about. In order to prevent the liquid phase adhesion of the grate bars generated during the sintering process, 1kg of sintered ore with a particle size of 10-16mm was placed on the grate bars of the sintering cup before the sintering started, and the charging amount of the sintering mixture was controlled at about 40kg. The layer thickness is controlled to 650mm. Using petroleum liquefied gas for sintering ignition, the sintering ignition temperature is controlled to 1100 ℃, the sintering ignition time is 1.5min, the sintering ignition negative pressure is controlled to 8KPa, the negative pressure of sintering and sintering process is controlled to 12KPa, and the sintering waste gas temperature starts to decrease from the highest point. At the end of sintering, the sintering ends when the exhaust gas temperature drops by 150° C. from the highest point, and the sintered ore of Example 3 is prepared.

Comparative example: take 15 parts of H ₃ BO ₃ and 85 parts of CaCl ₂ , prepare the additive of the comparative example, take 0.02 kg of the additive of the comparative example and dissolve it in 2 kg of water to make the additive solution of the comparative example; Test method The sintered ore of the comparative example was prepared.

Take the sintered ore of Examples 1 and 2 above, the sintered ore of the comparative example and the original sintered ore without any additives for mineral phase analysis and detection, and the detection results are shown in the following table (volume percentage).

Mineral composition content %

It can be seen from the above table that the main binding phases of the original sinter are calcium ferrite and dicalcium silicate, and the dicalcium silicate will undergo phase change and volume expansion during the reduction process of the sinter, which affects the reduction and pulverization performance of the sinter. . Compared with the original, the amount of calcium ferrite increased, the amount of dicalcium silicate and magnetite decreased, and the glass content did not change much. Compared with the comparative example, the amount of calcium ferrite in the example of the present invention is increased, and the amount of dicalcium silicate is decreased.

The mineral phase analysis of the sinter was carried out, and the sinter of the example, the sinter of the comparative example and the sinter without any additives were taken as optical thin slices, and the sinter was systematically identified by the Leica DM4P polarizing microscope. Among them, various mineral compositions are identified based on the knowledge of petrographic and mineralogy, mineral crystallography and crystal optics, according to the microstructure, microscopic appearance and color of various minerals. The mineral content refers to its volume percentage content, which is determined by the image analysis software of the Leica DM4P polarizing microscope using chromatic aberration analysis.

Fig. 1(a), Fig. 1(b), Fig. 1(c) The original mineral phase of the sintered ore. It can be seen from the figure that the original structure of the sintered ore is uneven, mainly in the spot-like structure, and partially in the interwoven erosion structure. The size of the pores is different, the distribution is uneven, the pores are many and the shape is irregular, and the porosity is 30%-35%. The content of calcium ferrite in the sinter is less, and the calcium ferrite is distributed in the form of plates and blocks; the amount of hematite is large, and the hematite is mostly heteromorphic, semi-hedromorphic, and skeletal structure, except that it is distributed in the sinter. The edge is also distributed in the middle of the sinter, as shown in Figure 1(a). This structure has a greater impact on the strength of the sinter. Magnetite is mainly semihedral-hedromorphic crystal, with a large content of silicate glass phase, and part of hyomorphic magnetite is cemented by glass to form a spot-like structure, as shown in Figure 1(c).

Figures 2(a) and 2(b) are the mineral phases of the comparative example. It can be seen from the figure that the mineral phase structure of the sintered ore of the comparative example is not uniform, mostly in the form of spot-like and sheet-like structures, and partially interwoven erosion structures. The pores are of different sizes, uneven distribution, many pores and irregular shapes, and the porosity is 35%-40%. By comparing Fig. 1(a), Fig. 1(b), Fig. 1(c), the content of calcium ferrite in the sintered ore of the comparative example has increased, the calcium ferrite is mostly fibrous and plate-like, and the magnetite is mainly semi Self-shaped and other-shaped crystals, and some other-shaped magnetites are cemented by calcium ferrite and dicalcium silicate to form an interwoven erosion structure, as shown in Figure 2(a). Hematite is mostly euhedral and has a skeletal structure, which is mostly distributed at the edge of the ore sample or the edge of the pores, as shown in Figure 2(b).

Figures 3(a) and 3(b) are the mineral phases of Example 1 of the present invention. It can be seen from the figure that the mineral phase structure of sinter is relatively uniform, mostly calcium ferrite and magnetite with interwoven erosion structure, and a small amount of porphyritic structure is distributed. The size of the pores is different, the distribution is uneven, the shape is irregular, the pores are mostly connected, and the porosity is 30%-35%. Calcium ferrite in sinter is mostly short plate-like and fibrous calcium ferrite structure. The amount of magnetite is mainly heteromorphic and semihedromorphic, and forms an eroded structure with calcium ferrite. Hematite is hematite-semihedral, which appears locally at the edge of pores or sinter, as shown in Figure 3(b).

Figure 4(a) and Figure 4(b) are mineral phases of Example 2 of the present invention. It can be seen from the figure that the mineral phase structure of the sinter is relatively uniform, and the interwoven erosion structure formed by calcium ferrite and magnetite is the main mineral phase, which is beneficial to increase the strength of the sinter. The stomata vary in size, regular in shape, and uneven in distribution, with a porosity of 35% to 40%. The content of calcium ferrite in the sinter is high, and it forms an erosion structure with magnetite, and the calcium ferrite is mostly needle-like and fibrous. Magnetite is mainly heteromorphic, mostly cemented by calcium ferrite, dicalcium silicate, calcium forsterite and vitreous to form a porphyritic-granular structure; hematite is mainly heteromorphic, with less content, and only occurs locally in mineral samples edge, as shown in Figure 4(b).

Example Compared with the original and the comparative example, the uniformity of the mineral phase structure of the sintered ore is increased, the amount of calcium ferrite is significantly increased, and the structure develops from massive and short plate to needle-like and fibrous. Dicalcium acid, vitreous, etc. are cemented to form an eroded structure, and the strength is increased. However, the proportion of porphyritic-granular structure with lower medium strength decreased, and the mineral phase structure of sinter was improved.

Claims (3)

1. A method for improving the phase structure of a sinter ore, which is characterized by comprising the following steps: adding an additive into the sintering mixture, wherein the additive comprises the following substances in parts by mass: h₃BO₃10-20，CaCl₂67-85，NaCl5-10，KMnO₄1-3。

2. The method of improving the phase structure of a sinter ore according to claim 1, wherein: the addition amount of the additive is 0.4-0.6 per mill of the sintering mixture.

3. The method of improving the phase structure of a sinter ore according to claim 2, wherein: the addition method of the additive comprises the following steps: weighing the additive according to the mixture ratio; mixing the additive and water according to the proportion of 1:100 of the additive and water, and fully stirring the mixture to prepare an additive solution; and in the sintering and first mixing process, all the additives are added into the sintering material and fully mixed, and then the second mixing and pelletizing are carried out.

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