Sintering mixture containing Laotian powder, sintering method thereof, and sintered ore

Abstract

This invention discloses a sintering mixture containing Lao powder, its sintering method, and the resulting sinter. The sintering mixture is prepared by mixing mixture I and mixture II twice. Mixture I includes Lao powder, direct-supply concentrate, Chengchao concentrate, and a first fuel. Mixture II includes iron ore powder, flux, and a second fuel. The iron ore powder includes PB powder, BRBF powder, FMG mixed powder, domestic iron concentrate, Brazilian concentrate, iron smelting gas ash, iron oxide scale, blast furnace return ore, lump ore return powder, dust collector ash, sludge, steel slag magnetic separation powder, and South African powder. The sintering mixture is then distributed, ignited, sintered, and screened to obtain the sinter. The sinter prepared by this invention has high basicity, good RDI performance, and a particle size of less than 10 mm, with less than 20% being sintered.

Description

Technical Field

[0001] This invention relates to the field of metallurgical sintering technology, and particularly to a sintering mixture containing Lao powder, a sintering method thereof, and sintered ore. Background Technology

[0002] Sintering is a process in which various powdered iron-containing raw materials are mixed with appropriate amounts of fuel and flux, and water. After mixing and pelletizing, the materials undergo a series of physicochemical changes on sintering equipment, agglomerating the mineral powder particles into lumps. Iron concentrate refers to the concentrate powder obtained from natural ore through crushing, grinding, and beneficiation. It is characterized by high grade, low S and P impurities, and low loss on ignition. It is an essential component of iron-containing materials in sintering blends and helps improve the yield. However, iron concentrate has a loss on ignition of 1.7% and a particle size of 0.1-0.2 mm. When too much is added, its pelletizing performance deteriorates due to the lack of pelletizing nuclei, reducing the permeability of the material layer. At the same time, its price is relatively high, increasing the cost of sintering blends. Lao powder has become an excellent substitute for iron concentrate in recent years, but its high silica content can easily lead to a decrease in the basicity of the sinter during sintering, resulting in a reduction in the low-temperature reduction pulverization (RDI) performance of the sinter.

[0003] Therefore, it is essential to study a sintering method that can reduce the cost of ore blending while improving the basicity and RDI performance of sinter and reducing the particle size of finished ore below 10 mm. Summary of the Invention

[0004] To address the shortcomings of the existing technologies, this invention provides a mixture containing Lao powder for sintering, a sintering method thereof, and sintered ore, comprising the following technical solutions:

[0005] A sintering mixture containing Lao powder includes mixture I and mixture II. Mixture I is mixed with water for the first time, then mixture II is added, and water is added for the second time to obtain the sintering mixture.

[0006] Mixture I includes Lao powder, direct-supply concentrate, Chengchao concentrate, and the first fuel; Mixture II includes iron ore powder, flux, and the second fuel. Based on the mass of the iron-containing raw materials as 100%, Mixture I includes 2-4% Lao powder, 5-9% direct-supply concentrate, and 1-3% Chengchao concentrate; Mixture II includes 88% iron ore powder. The mass of the iron-containing raw materials is calculated as the sum of the masses of Lao powder, direct-supply concentrate, Chengchao concentrate in Mixture I, and iron ore powder in Mixture II. The mass of the first fuel is greater than that of the second fuel.

[0007] Preferably, the mass ratio of iron-containing raw materials, flux and fuel is (82-83):(12.5-13):(4.6-4.7), and the fuel includes a first fuel and a second fuel;

[0008] Preferably, before the second mixing, in addition to adding mixture II, sintered return ore is also added, and the mass of sintered return ore is 25% of the total mass of mixture I and mixture II.

[0009] Preferably, the iron ore powder in mixture II includes 36% PB powder, 28% BRBF powder, 23% FMG mixed powder, 3% domestic iron concentrate, 4% Brazilian concentrate, 1% iron smelting gas ash, 0.6% iron oxide scale, 1.1% blast furnace return ore, 0.4% lump ore return powder, 0.1% dust collector ash, 0.7% sludge, 1.3% steel slag magnetic separation powder, and 0.8% South African powder.

[0010] Preferably, the proportion of iron-containing raw materials with a particle size greater than 10 mm is less than 3%.

[0011] Preferably, both the first fuel and the second fuel are mixtures of coke powder and alumina, with a fuel particle size of <25mm, alumina moisture content of <10%, and ≥70% of the coke powder having a particle size of less than 3mm.

[0012] Preferably, the flux is a combination of quicklime, limestone, or dolomite, wherein ≥90% of the quicklime, limestone, or dolomite has a particle size of less than 3mm; the quicklime contains ≥83% CaO and has an activity of ≥220; the limestone has a moisture content of ≤5%; and the dolomite has a moisture content of ≤5%.

[0013] Preferably, the initial water addition is 8-10 t / h, the filling rate is 10-13%, the mixing time is 2-4 min, and the mixing speed is 6-8 r / min.

[0014] Preferably, the second mixing water addition is 2-4 t / h, the filling rate is 11-15%, the mixing time is 3-6 min, and the mixing speed is 6-8 r / min.

[0015] The present invention also provides a sintering method for the above-mentioned sintering mixture containing Lao powder, comprising the following steps:

[0016] The sintering mixture is placed on a trolley with a base material, and the particle size of the sintering mixture gradually increases from top to bottom; after ignition, sintering, cooling, and screening, sintered ore is obtained.

[0017] Preferably, the base material is made of sintered ore with a particle size of 10-20 mm and a thickness of 30-40 mm.

[0018] Preferably, the ignition temperature is 1050–1200℃, the ignition time is 40–70s, and the holding time is 60–120s.

[0019] Preferably, the sintering negative pressure is 16–20 kPa.

[0020] The present invention also provides a sinter containing Lao powder, wherein the sinter contains, by mass fraction, 56-57% TFe, 4.86-5.25% SiO2, 1.98-2.22% Al2O3, 9.91-10.45% CaO, 2.01-2.18% MgO, and 8.62-9.82% FeO.

[0021] Compared with the prior art, the advantages of the present invention are:

[0022] 1. The first uniform mixing of Lao powder, direct-supply concentrate, Chengchao concentrate, and some fuel can serve as an excellent pelletizing core. The addition of large particles allows the blended ore obtained after the adhering of mix I to mix II to increase the permeability of the fabric layer while generating more low-eutectic-point substances. This increases the amount of liquid phase in the sintering combustion zone, ensuring sufficient liquid phase solidification and improving the low-temperature reduction pulverization (RDI) performance of the sinter, reaching 68.4%. It also increases the basicity of the sinter (R = CaO / SiO2) to 2.0–2.1. Simultaneously, the proportion of sinter particles smaller than 10mm is less than 20%, thus improving the overall quality of the sinter. The addition of Lao powder reduces the amount of iron concentrate used, resulting in high-quality sinter while lowering blending costs.

[0023] 2. When the sintering mixture is distributed, the particle size is gradually increased from top to bottom. This can increase the air permeability of the material layer and facilitate the complete combustion of the first and second fuels during sintering. It also increases the heat storage temperature of the sintering material layer and increases the amount of liquid phase generated during overall sintering. This is beneficial to further improving the sintering yield, sintering RDI, and drum strength.

[0024] 3. The return ore in the sintering process is a defective product from the previous sintering. It is mixed a second time before this sintering, which helps to improve the permeability of the sintering material layer. Since it contains iron, re-firing is environmentally friendly and economical, and also avoids the waste of iron. Detailed Implementation

[0025] To further illustrate the present invention, the technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0026] This invention provides a preferred sintering method for a mixture containing Lao powder for sintering, specifically including the following steps:

[0027] Mixture I is fed into a cylindrical mixer, and water is added at a rate of 8–10 t / h for the first mixing, with a filling rate of 10–13%, a mixing time of 2–4 min, and a mixer speed of 6–8 r / min. Then, mixture II is added, and water is added at a rate of 2–4 t / h for the second mixing, with a filling rate of 11–15%, a mixing time of 3–6 min, and a mixer speed of 6–8 r / min, to obtain the sintering mixture. The sintering mixture is evenly fed into the mixing trough of the sintering machine using a shuttle feeder, and then evenly distributed on a trolley with a bottom material laid by a roller feeder and a nine-roller feeder. The bottom material consists of sintered ore with a particle size of 10–20 mm and a thickness of 30–40 mm. The particle size of the sintering mixture segregates from top to bottom, gradually increasing in size. After ignition, sintering, cooling, and screening, sintered ore is obtained.

[0028] Mixture I includes Lao powder, direct-supply concentrate, Chengchao concentrate, and primary fuel; Mixture II includes iron ore powder, flux, and secondary fuel. Based on the iron-containing raw material mass of 100%, Mixture I includes 2–4% Lao powder, 5–9% direct-supply concentrate, and 1–3% Chengchao concentrate; Mixture II includes 88% iron ore powder. The mass of the iron-containing raw material refers to the total mass of Lao powder, direct-supply concentrate, Chengchao concentrate in Mixture I, and iron ore powder in Mixture II.

[0029] The iron ore powder includes 36% PB powder, 28% BRBF powder, 23% FMG mixed powder, 3% domestic iron concentrate, 4% Brazilian concentrate, 1% iron smelting gas ash, 0.6% iron oxide scale, 1.1% blast furnace return ore, 0.4% lump ore return powder, 0.1% dust collector ash, 0.7% sludge, 1.3% steel slag magnetic separation powder, and 0.8% South African powder;

[0030] Both the first fuel and the second fuel are mixtures of coke powder and alumina, with the first fuel having a larger mass than the second fuel; the flux consists of various types of quicklime, limestone, and dolomite.

[0031] The technical solution of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] Examples 1-5

[0033] Examples 1-5 provide a sintering method for a mixture containing Lao powder for sintering, specifically including the following steps:

[0034] Mixture I is added to a cylindrical mixer, water is added for the first mixing, then mixture II is added, water is added for the second mixing, and a sintering mixture is obtained. A shuttle feeder is used to evenly feed the sintering mixture into the mixing trough of the sintering machine, and then a roller feeder and a nine-roller feeder are used to evenly distribute the mixture on a trolley with a base material. The sintering mixture segregates from top to bottom, gradually increasing in size. After ignition, sintering, cooling, and screening, sintered ore is obtained.

[0035] The data of iron-containing raw materials used in Examples 1 to 5 are shown in Table 1, the specific raw material ratios are shown in Table 2, the process parameters for sintering are shown in Tables 3 and 4, and the chemical composition and performance indicators of the prepared sinter are shown in Table 5.

[0036] Example 6

[0037] Example 6 provides a sintering method for a mixture containing Lao powder for sintering, which is basically the same as Example 1. The difference is that before the second mixing, in addition to adding mixture II, sintering return ore is also added. The mass of sintering return ore is 25% of the total mass of mixture I and mixture II.

[0038] The data of the iron-containing raw materials used in Example 6 are shown in Table 1, the specific raw material ratio is shown in Table 2, the process parameters for sintering are shown in Tables 3 and 4, and the chemical composition and performance indicators of the prepared sinter are shown in Table 5.

[0039] Comparative Example 1

[0040] Comparative Example 1 provides a sintering method for a sintering mixture, which is basically the same as that of Example 1, except that the Lao powder in mixture I is replaced entirely with directly supplied refined powder.

[0041] The data of iron-containing raw materials used in Comparative Example 1 are shown in Table 1, the specific raw material ratio is shown in Table 2, the process parameters for sintering are shown in Tables 3 and 4, and the chemical composition and performance indicators of the prepared sinter are shown in Table 5.

[0042] Comparative Example 2

[0043] Comparative Example 2 provides a sintering method for a sintering mixture, which is basically the same as that of Example 1, except that the mixture I containing Lao powder is not pre-pelletized, but the mixture I and the mixture II are put into the mixer for total mixing.

[0044] The data of iron-containing raw materials used in Comparative Example 2 are shown in Table 1, the specific raw material ratio is shown in Table 2, the process parameters for sintering are shown in Tables 3 and 4, and the chemical composition and performance indicators of the prepared sinter are shown in Table 5.

[0045] Table 1 Data on iron-containing raw materials

[0046]

[0047]

[0048] The particle size in Table 1 represents the combined particle size of each iron-containing raw material.

[0049] Table 2 Raw material ratio

[0050]

[0051] In Table 2, the iron ore powder in Examples 1-6 and Comparative Examples 1-2 is composed of 36% PB powder, 28% BRB F powder, 23% FMG mixed powder, 3% domestic iron concentrate, 4% Brazilian concentrate, 1% iron smelting gas ash, 0.6% iron oxide scale, 1.1% blast furnace return ore, 0.4% lump ore return powder, 0.1% dust collector ash, 0.7% sludge, 1.3% steel slag magnetic separation powder, and 0.8% South African powder, so it is omitted from the table.

[0052] In Table 2, the flux is a variety of quicklime, limestone, and dolomite. For example, in some examples, the flux is a mixture of quicklime and limestone; in other examples, the flux is a mixture of quicklime, limestone, and dolomite.

[0053] In Table 2, the fuel includes the first fuel of mixture I and the second fuel of mixture II, with the first fuel having a larger mass than the second fuel. Both the first and second fuels are mixtures of coke powder and albite. For example, in some examples, the first fuel accounts for 75% of the total fuel and the second fuel accounts for 25% of the total fuel; in other examples, the first fuel is 2.3 to 3.1 times the mass of the second fuel.

[0054] Table 3 Control of process parameters during sintering

[0055]

[0056] Table 4 is a continuation of Table 3.

[0057]

[0058] Table 5 Chemical composition and performance indicators of sintered ore

[0059]

[0060] As shown in Table 5, the basicity of the sinter prepared in Examples 1 to 6 was 2.0 to 2.1, the drum strength all exceeded 77, the RDI reached more than 62%, and the proportion of sinter particles with a diameter <10mm was less than 20%. This indicates that by reducing the amount of iron concentrate and adding Lao powder, the low-temperature reduction pulverization and drum strength performance of the sinter can be improved. At the same time, the sinter prepared has high basicity and a small proportion of particles with a diameter less than 10mm, thus reducing the cost of ore blending.

[0061] Compared with Example 1, the basicity R, drum strength, and low-temperature reduction pulverization RDI performance of the sinter in Comparative Example 1 decreased significantly, and the proportion of particles with a diameter <10mm in the sinter exceeded 40%. This was because the lack of large-diameter Lao powder and the use of fine powder instead resulted in unsatisfactory pelletizing effect during the mixing process, which in turn led to poor permeability of the material layer, low liquid phase content, and incomplete fuel combustion during the sintering process, ultimately resulting in poor sinter quality.

[0062] Compared with Example 1, the basicity R, drum strength, and low-temperature reduction pulverization (RDI) performance of the sinter in Comparative Example 2 decreased to a certain extent, and the proportion of sinter with a particle size <10mm reached 36.45%. This is because the mixture I containing Lao powder was not pre-pelletized, but was instead mixed together with mixture II in the mixer. This resulted in poor pelletizing effect, and the material layer could not provide good air permeability during the sintering process after the material was distributed. The amount of liquid phase generated was small, the consolidation effect was poor, and ultimately the quality of the sinter was poor.

[0063] The above detailed embodiments describe the implementation of the present invention; however, the present invention is not limited to the specific details described in the above embodiments. Within the scope of the claims and technical concept of the present invention, various simple modifications and changes can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

Claims

1. A sintering mixture containing Lao powder, characterized in that, Mixing material I with water for the first time, then adding material II and mixing with water for the second time, yields the final product; Mixture I comprises Lao powder, direct-supply concentrate, Chengchao concentrate, and a first fuel; Mixture II comprises iron ore powder, flux, and a second fuel. Based on the mass of the iron-containing raw materials as 100%, Mixture I comprises 2-4% Lao powder, 5-9% direct-supply concentrate, and 1-3% Chengchao concentrate; Mixture II comprises 88% iron ore powder. The mass of the iron-containing raw materials is calculated as the sum of the masses of the Lao powder, direct-supply concentrate, Chengchao concentrate in Mixture I, and the iron ore powder in Mixture II. The mass of the first fuel is greater than that of the second fuel. The iron ore powder in Mixture II includes 36% PB powder, 28% BRBF powder, 23% FMG mixed powder, 3% domestic iron concentrate, 4% Brazilian concentrate, 1% iron smelting gas ash, 0.6% iron oxide scale, 1.1% blast furnace return ore, 0.4% lump ore return powder, 0.1% dust collector ash, 0.7% sludge, 1.3% steel slag magnetic separation powder, and 0.8% South African powder.

2. The sintering mixture according to claim 1, characterized in that, The mass ratio of the iron-containing raw material, the flux, and the fuel is (82~83):(12.5~13):(4.6~4.7), and the fuel includes the first fuel and the second fuel.

3. The sintering mixture according to claim 1, characterized in that, Before the second mixing, in addition to adding the mixture II, sintered return ore was also added, and the mass of the sintered return ore was 25% of the total mass of the mixture I and the mixture II.

4. The sintering mixture according to claim 1, characterized in that, The initial mixing water addition is 8-10 t / h, the filling rate is 10-13%, the mixing time is 2-4 min, and the mixing speed is 6-8 r / min.

5. The sintering mixture according to claim 1, characterized in that, The second mixing water addition is 2~4t / h, the filling rate is 11~15%, the mixing time is 3~6min, and the mixing speed is 6~8r / min.

6. A sintering method for a sintering mixture containing Lao powder, characterized in that, The application of the sintering mixture according to any one of claims 1 to 5 includes the following steps: The sintering mixture is placed on top of the bottom material layer, and the particle size of the sintering mixture gradually increases from top to bottom during the placement process; after ignition, sintering, cooling, and screening, sintered ore is obtained.

7. The sintering method according to claim 6, characterized in that, The temperature during the ignition process is 1050~1200℃, the ignition time is 40~70s, and the holding time is 60~120s.

8. A sintered ore containing Lao powder, characterized in that, Prepared by the method described in claim 6 or 7.

9. The sintered ore according to claim 8, characterized in that, The sintered ore contains, by mass percentage, 56-57% TFe, 4.86-5.25% SiO2, 1.98-2.22% Al2O3, 9.91-10.45% CaO, 2.01-2.18% MgO, and 8.62-9.82% FeO.

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