A kind of ore-returning inlay sintering process

Abstract

The present invention provides a return ore inlay sintering process, comprising the following steps: batching, first mixing, second mixing granulation, material distribution, ignition, sintering, crushing cooling, screening, and sintered ore index detection; wherein, the base material equipped in the batching includes: by weight, return ore (30-35) parts, coke powder (3.5-4.0) parts, quicklime (5.5-7.0) parts, dolomite powder (2.0-3.0) parts, and mixed powder (51-53 parts); before the first mixing step, the return ore is screened, and the return ore with a particle size of 0-3 mm is first mixed with the coke powder, quicklime, dolomite powder, and mixed powder for first mixing and second mixing granulation to obtain a second mixed sintering material, and then the return ore with a particle size of 3-7 mm is mixed with the second mixed sintering material, and then the subsequent process is carried out. The process of the present invention makes the sintering output, sintering strength and metallurgical properties all maintain relatively good at the same time.

Description

Technical Field

[0001] The invention relates to the technical field of iron and steel metallurgy, in particular to a return ore inlay sintering process. Background Art

[0002] With the gradual improvement of blast furnace production requirements for sintered ore and quality, the efficient use of mineral resources has become a consensus among researchers. Return ore is the internal circulation material in the sintering process. Sintered ore return ore refers to the sintered ore that is not completely burned, including the sintered ore along the sides and surface of the sintering machine trolley, the powder produced after mechanical load, the dust and mud recovered by environmental dust removal, and other fine powders that need to be returned to the sintering process. They are generally less than 5-6mm. A high proportion of return ore addition will have a significant impact on the sintering process and the quality of the sintered ore.

[0003] Return ore mosaic sintering is a new sintering process. The mosaic iron ore sintering technology was first proposed by Eiki Kasai of Tohoku University in Japan. This process uses Malamamba ore to prepare green balls and distributes them evenly in the sintering material layer, so that the sintering material layer forms a suitable void structure, achieving the effect of changing the quality of sintered ore and increasing the output of sintered ore.

[0004] However, there is relatively little research on the existing technology of return ore inlay sintering. Studying the return ore inlay process suitable for the current raw material and fuel conditions, further improving the permeability of the material layer and the sintering efficiency, strengthening the sintering effect, and increasing the sintering output are the key to reducing the production pressure of the sintering plant. Summary of the invention

[0005] In order to solve the defects in the prior art, the present invention provides a return ore inlay sintering process, so that the sintering output, sintering strength and metallurgical properties are all maintained at a relatively good level at the same time.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] The invention provides a return ore inlay sintering process, comprising the following steps: batching, first mixing, second mixing granulation, material distribution, ignition, sintering, crushing cooling, screening, and sintered ore index detection; wherein the base material prepared in the batching comprises: in parts by weight, return ore (30-35) parts, coke powder (3.5-4.0) parts, quicklime (5.5-7.0) parts, dolomite powder (2.0-3.0) parts, and mixed powder (51-53) parts; before the first mixing step, the return ore is screened, and the return ore with a particle size of 0-3 mm is firstly mixed with the coke powder, quicklime, dolomite powder, and mixed powder for first mixing and second mixing granulation to obtain a second mixing sintering material, and then the return ore with a particle size of 3-7 mm is mixed with the second mixing sintering material, and then subsequent processes are carried out. That is, in the present invention, the return ore with a particle size of 3 to 7 mm does not participate in the first and second mixing granulation steps, but is directly added to the sintered material after the second mixing granulation.

[0008] Preferably, the return ore in the base material is a sintered ore with a particle size less than 7 mm.

[0009] Preferably, the mixed powder is composed of the following by weight percentage: 68% fine powder, 19% mineral powder, 11% iron-containing recycled materials, and 2% steel slag.

[0010] Preferably, the base material prepared in the batch includes: in parts by weight, 35 parts of return ore, 3.9 parts of coke powder, 6.8 parts of quicklime, 2.8 parts of dolomite powder, and 51.5 parts of mixed powder.

[0011] Preferably, the chemical composition of the sintered ore of the base material is as follows: basicity R is (2.2-2.7), TFe (47.0-50.0)%, SiO2 (5.0-5.8)%, CaO (13-17)%, MgO (2.6-3.0)%, Al2O3 (2.5-3.5)%, S (0.07-0.12)%, P (0.06-0.12)%, TiO2 (4.0-5.8)%, V2O5 (0.3-0.45)%. R refers to the basicity of the sintered ore, that is, the percentage of CaO / SiO2 in the sintered ore, R=CaO / SiO2.

[0012] More preferably, the chemical composition of the sintered ore of the base material is: basicity R is 2.64, TFe 48.51%, SiO2 5.66%, CaO 14.91%, MgO 2.81%, Al2O3 2.7%, S 0.09%, P 0.083%, TiO2 4.26%, and V2O5 0.38%.

[0013] It should be noted that the return ore with a particle size of 3 to 7 mm is mixed evenly with the second mixed sintering material, which is the return ore inlay, and the particle size is the return ore inlay particle size.

[0014] Preferably, the particle size of the returned ore inlay is 3 to 5 mm.

[0015] Preferably, the returned ore inlay ratio is 40% to 100%, that is, 40% to 100% of the returned ore with a particle size of 3 to 7 mm is used for inlay. More preferably, the returned ore inlay ratio is 40% to 80%, and more preferably, the returned ore inlay ratio is 80%.

[0016] Among them, the sintering material layer is evenly divided into three layers of upper, middle and lower, and the returned ore is embedded in different layers.

[0017] Preferably, the return ore embedding position is the lower layer or the lower-middle layer of the sintered layer.

[0018] More preferably, the return ore embedding position is the middle and lower layers of the sintered layer.

[0019] In the ore-returning inlay sintering process of the present invention:

[0020] Preferably, the mixing time is 4 minutes.

[0021] Preferably, the amount of water added in the first mixing process is 7% of the mass of the base material.

[0022] Preferably, the second mixing granulation time is 5 minutes.

[0023] Preferably, 0.5% to 1% of the mass of water of the first mixed material is added during the second mixing granulation process.

[0024] Preferably, the thickness of the sintering material layer during the sintering process is 750-800 mm.

[0025] Preferably, during the ignition process, the ignition temperature is 1150° C., the ignition time is 1 min, and the ignition negative pressure is 11 kPa.

[0026] Preferably, the sintering negative pressure during the sintering process is 16 kPa.

[0027] The beneficial effects of the present invention are:

[0028] In the return ore inlay process of the present invention, when the inlaid return ore particle size is 3-7 mm, the return ore can form a suitable void structure with the sintered material after the second mixing granulation, and the vertical sintering speed and the utilization coefficient can be kept relatively good, indicating that a relatively good sintering yield is achieved at this time, wherein the best is achieved when the inlaid return ore particle size is 3-5 mm; the return ore inlay particle size is 3-7 mm return ore, while maintaining a relatively high sintering yield, the sintered ore can obtain better strength, and the sintered ore particle size distribution is more uniform, wherein the best is achieved when the inlaid return ore particle size is 3-5 mm, and the strength is about 67%, and the return ore inlay particle size has no obvious effect on the metallurgical properties of the sintered ore, and the return ore with a particle size of 3-7 mm can make the sintered ore have good metallurgical properties.

[0029] The present invention studies different ratios of return ore inlay. As the inlay ratio increases, the air permeability of the entire material layer gradually improves. The higher the inlay ratio, the better the air permeability of the material layer. To obtain a good sintering yield and sintering strength at the same time, the return ore inlay ratio should be 40% to 100%. Among them, as the return ore inlay ratio increases from 20% to 80%, the vertical sintering speed and sintering utilization coefficient show an upward trend. The vertical sintering speed increases by about 4.5mm / min, and the sintering utilization coefficient increases by about 0.5t / m 2h. When the return ore inlay ratio is 80%, the vertical sintering speed and sintering utilization coefficient are the highest. The anti-wear index shows an overall increasing trend. When the return ore inlay ratio is 40%-100%, the anti-wear index increases. With the increase of the return ore inlay ratio, the sintered ore with a particle size of <10mm decreases, and the sintered ore with a particle size of 10-16mm, 16-25mm and 25-40mm increases, and the particle size distribution of the sintered ore is more reasonable.

[0030] The present invention explores the position of return ore inlay. When the return ore inlay is close to the lower part and the middle and lower part, the sintering speed and utilization coefficient are better than those of the upper part; when the return ore inlay is close to the lower part, the strength of the sintered ore decreases slightly, which may be due to the accelerated sintering speed and shortened high-temperature holding time, resulting in reduced strength. The sintering strength of the middle and lower part is higher than that of the lower part, while the wear resistance index of the upper, middle and lower parts is equivalent to that of the lower part, which is significantly better than other positions; on the whole, when the return ore is inlaid in the lower part and the middle and lower part of the sintering material layer, the reducibility of the sintered ore is higher than that of the sintered ore only inlaid in the upper part; in summary, when the return ore inlay is in the middle and lower part, the sintering output, sintering strength and metallurgical properties of the sintered ore are all better. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is the vertical sintering speed of different returned ore inlay particle sizes;

[0032] Figure 2 is the sintering utilization coefficient of different returned ore inlay particle sizes;

[0033] Figure 3 The firing rate of different returned ore inlay particle sizes;

[0034] Figure 4 The drum strength of different returned ore inlay particle sizes;

[0035] Figure 5 The particle size distribution of finished ore with different returned ore inlay particle sizes;

[0036] Figure 6 High temperature softening performance of sintered ore with different return ore inlay particle sizes;

[0037] Figure 7 The droplet performance of sintered ore with different return ore inlay particle sizes;

[0038] Figure 8 is the softening temperature of sintered ore with different return ore inlay particle sizes;

[0039] Fig. 9 is the air permeability index of different return ore inlay ratios;

[0040] Fig.10 is the vertical sintering speed of different return ore inlay ratios (0% to 50%);

[0041] Fig.11The vertical sintering speed of different return ore inlay ratios (20% to 80%);

[0042] Fig.12 is the sintering utilization coefficient of different return ore inlay ratios (20% to 80%);

[0043] Fig.13 is the firing rate of different return ore inlay ratios;

[0044] Fig.14 The strength of the drum with different return ore inlay ratios;

[0045] Fig.15 is the anti-wear index of different return ore inlay ratios;

[0046] Fig.16 The particle size distribution of finished ore with different return ore inlay ratios;

[0047] Fig.17 To test the reducibility of sintered ore with different return ore inlay ratios;

[0048] Fig.18 To test the molten dripping performance of different return ore inlay ratios;

[0049] Fig.19 To test the softening performance of different return ore inlay ratios;

[0050] Fig. 20 is the vertical sintering speed at different return ore embedding positions;

[0051] Fig.21 is the sintering utilization coefficient of different return ore embedding positions;

[0052] Fig. 22 is the firing rate of different return ore inlay positions;

[0053] Fig.23 The drum strength at different return ore embedding positions;

[0054] Fig.24 is the anti-wear index of different return ore embedding positions;

[0055] Fig.25 The particle size distribution of finished ore at different return ore inlay positions;

[0056] Fig.26 To test the reducibility of sintered ore at different return ore embedding positions;

[0057] Fig. 27 is the softening temperature of sintered ore at different return ore embedding positions. DETAILED DESCRIPTION

[0058] In order to enable those skilled in the art to better understand the technical solution of the invention, the present invention is further described in detail below in conjunction with specific implementation methods.

[0059] Example 1

[0060] The ore-returning inlay sintering process of this embodiment is as follows:

[0061] (1) The ore blending scheme of this embodiment is shown in Table 1, wherein the composition and ingredients of the mixed powder 28# ore powder are shown in Table 2 (all of which are ore powders known in the art and commercially available), and the chemical composition of the sintered ore of the base material is shown in Table 3;

[0062] (2) Return ore screening: Sintered ore with a particle size of less than 7 mm is screened out as return ore, which is then screened into return ore with a particle size of 0 to 3 mm and return ore with a particle size of 3 to 7 mm;

[0063] (3) First mixing: the returned ore with a particle size of 0 to 3 mm, the coke powder, quicklime, dolomite powder and mixed powder are put into a mixer and mixed for 4 minutes, and 7% of the mass of the base material is added with water;

[0064] (4) Secondary mixing and granulation: the material obtained in the first mixing of step (3) is added to the secondary mixing drum machine for mixing and granulation for 5 minutes, and water accounting for 0.5% to 1% of the mass of the first mixed material is added to obtain a second mixed sintered material; at this time, the return ore with a particle size of 3 to 7 mm is mixed with the second mixed sintered material;

[0065] (5) Material distribution: The material obtained in step (4) is loaded into the sintering trolley through a material distributor, and the material layer thickness is controlled to be 800 mm;

[0066] (6) Ignition: The sintering trolley is ignited at 1150°C for 1 min, and the ignition negative pressure is controlled to be 11 kPa;

[0067] (7) Sintering: After ignition is completed, adjust the sintering negative pressure to 16 kPa;

[0068] (8) Crushing and cooling;

[0069] (9) Screening: The sintered ore after cooling and crushing is screened to obtain sintered ore with a particle size of less than 7 mm as return ore; (10) Sintered ore index detection: see effect examples 1 to 3.

[0070] Table 1 Ore blending scheme (mass fraction %)

[0071]

[0072] Table 2 Composition and ingredients of mixed powder 28#

[0073]

[0074]

[0075] Table 3 Chemical composition of sintered ore (mass fraction%)

[0076]

[0077] Example 2

[0078] The ore return inlay sintering process of this embodiment is the same as that of embodiment 1, the only difference being the different ore blending scheme. The ore blending scheme of this embodiment is shown in Table 4, and the chemical composition of the sintered ore of the base material is shown in Table 5.

[0079] Table 4 Ore blending scheme (mass fraction %)

[0080]

[0081] Table 5 Chemical composition of sintered ore (mass fraction%)

[0082]

[0083] Example 3

[0084] The ore-returning and inlaying sintering process of this embodiment is the same as that of embodiment 1, and the only difference is the ore blending scheme. The ore blending scheme of this embodiment is shown in Table 6, and the chemical composition of the sintered ore of the base material is shown in Table 7.

[0085] Table 6 Ore blending scheme (mass fraction %)

[0086]

[0087] Table 7 Chemical composition of sintered ore (mass fraction%)

[0088]

[0089] Effect Example 1 Effect of different returned ore inlay particle sizes on sintering process indicators

[0090] The returned ore inlay particle sizes of <1mm, 1-3mm, 3-5mm, 5-7mm and >7mm were selected for testing, the inlay ratio was controlled to 100%, and the returned ore was inlaid into the entire sintering material layer. The test adopted the on-site production plan:

[0091] 1. The influence of the particle size of returned ore on sintering output

[0092] Depend on Figure 1 and Figure 2It can be seen that as the particle size of the returned ore gradually increases, the vertical sintering speed and utilization factor show a trend of first increasing and then decreasing. On the whole, the vertical sintering speed and utilization factor of the particle size greater than 1 mm are higher than those of the particle size less than 1 mm. When the particle size of the returned ore is 3-5 mm, the vertical sintering speed and utilization factor are optimal. This is because when the returned ore of appropriate particle size is inlaid, the returned ore can form a suitable void structure with the sintered material after the second mixing granulation, thereby increasing the vertical sintering speed. When the returned ore particle size is too large or too small, it is quite different from the particle size of the iron ore powder after the second mixing granulation, and an effective void cannot be formed, resulting in a decrease in the permeability of the sintering material layer, which in turn leads to a decrease in the sintering speed and utilization factor.

[0093] Depend on Figure 3 It can be seen that as the particle size of the returned ore gradually increases, there is no obvious change in the firing of the sintered ore overall, indicating that the particle size of the returned ore has no obvious effect on the firing rate.

[0094] 2. Effect of returned ore embedding particle size on sintering strength

[0095] Depend on Figure 4 It can be seen that the strength of the sintered ore with the returned ore with a particle size greater than 1mm is higher than that of the returned ore with a particle size <1mm. Among them, the sintered ore with the returned ore with a particle size of 1-3 and 3-5mm has a better strength, which is about 67%, while the strength of the sintered ore with the returned ore with a particle size of 5-7 and >7mm is not much different.

[0096] Depend on Figure 5 It can be seen that compared with the inlaid particle size of return ore <1mm, after inlaying the return ore with larger particle size, the sintered ore with particle size <10mm decreases, the sintered ore with particle size of 10-16mm increases, and the particle size distribution of the sintered ore is more uniform. When the inlaid particle size of the return ore is 3-5mm, the particle size distribution of the sintered ore is the most uniform.

[0097] 3. Effect of returned ore embedding particle size on the metallurgical properties of sintered ore

[0098] Depend on Figure 6 to Figure 8 It can be seen that the inlay of return ore with different particle sizes has no obvious effect on the high-temperature softening performance and molten drop performance of the sintered ore; after inlaying return ore with different particle sizes, the softening start temperature of the finished sintered ore is 1098±10℃, the softening range is 100±4℃, the melting start temperature is 1210±10℃, and the melting range is about 240℃. There is no obvious change in the high-temperature metallurgical properties, indicating that the inlay particle size of the return ore has no obvious effect on the metallurgical properties of the sintered ore.

[0099] In summary, if you want to obtain better sintering yield, sintering strength and metallurgical properties at the same time, the returned ore inlay particle size should be 3-7 mm; further, the returned ore inlay particle size should be 3-5 mm.

[0100] Effect Example 2 Effect of different return ore inlay ratios on sintering process indicators

[0101] Different ratios of return ore inlay were selected for testing, the return ore particle size was controlled to be 3-7 mm, and the return ore was inlaid into the entire sintering material layer. The test adopted the on-site production plan:

[0102] 1. The influence of return ore inlay ratio on sintering process

[0103] Depend on Fig. 9 It can be seen that with the increase of the inlay ratio, the air permeability of the entire material layer gradually improves, especially in the first half of sintering (750 seconds), the higher the inlay ratio, the better the air permeability of the material layer; in the second half of sintering, the air permeability of the material layer after inlaying the return ore is generally better than that of the sintered material layer without inlaying the return ore. This is because the inlay of the sintered material layer with the return ore can form a suitable void structure during the sintering process, improve the air permeability of the material layer, and utilize the edge effect near the large particle return ore to improve the air permeability of the material layer. At the same time, the large particle return ore itself will not be over-melted, and finally the sintered material layer can form a better void structure, ensuring good sintering permeability and sintering effect.

[0104] Depend on Fig.10 It can be seen that as the embedding ratio increases from 0% to 50%, the vertical sintering speed shows an overall upward trend, increasing from about 22 mm / min to 27 mm / min, and the sintering speed is significantly improved.

[0105] 2. The influence of return ore inlay ratio on sintering output

[0106] Depend on Fig.11 and Fig.12 It can be seen that as the return ore inlay ratio increases from 20% to 80%, the vertical sintering speed and sintering utilization factor show an upward trend, among which the vertical sintering speed increases by about 4.5mm / min, and the sintering utilization factor increases by about 0.5t / m 2 ·h, the vertical sintering speed and sintering utilization coefficient are the highest when the return ore embedding ratio is 80%.

[0107] Depend on Fig.13 It can be seen that with the increase of the inlay ratio, the firing rate decreases slightly. This may be because, with the increase of the return ore inlay ratio, the permeability of the material layer becomes better, the sintering speed is accelerated, and the insulation time is shortened, resulting in a slight decrease in the firing rate, but the overall impact is not significant.

[0108] 3. Effect of return ore inlay ratio on sintering strength

[0109] Depend on Fig.14 It can be seen that as the return ore inlay ratio increases from 0% to 100%, the sintered ore drum strength decreases slightly (by 3%), indicating that the inlay of return ore during the sintering process will affect the drum strength to a certain extent, but the overall impact is not significant. When the return ore inlay ratio is 80%, the impact is the smallest and the drum strength is the best.

[0110] Depend on Fig.15 It can be seen that the anti-wear index shows an overall increasing trend. When the return ore inlay ratio is 20%, the anti-wear index will decrease, and when the return ore inlay ratio is 40% to 100%, the anti-wear index increases.

[0111] Depend on Fig.16 It can be seen that with the increase of the return ore inlay ratio, the sintered ore with a particle size of <10mm decreases, the sintered ore with a particle size of 10-16mm, 16-25mm and 25-40mm increases, and the particle size distribution of the sintered ore becomes more reasonable. When the return ore inlay ratio is 80%, the particle size distribution of the sintered ore is the most reasonable.

[0112] 4. Effect of return ore embedding ratio on metallurgical properties of sintered ore

[0113] Depend on Fig.17 It can be seen that as the return ore embedding ratio increases from 0% to 100%, the RI of the sintered ore increases slightly, but remains basically unchanged at about 66%. The low-temperature reduction powder index RDI of the sintered ore is +3.15 and RDI -0.5 There is no obvious change, and they remain at about 69% and 8.6% respectively, indicating that the return ore inlay sintering has no obvious effect on the high-temperature metallurgical properties of the finished sintered ore.

[0114] Depend on Fig.18 and Fig.19 It can be seen that after inlaying different proportions of return ore, the softening performance and melting dripping performance of the sintered ore remain basically unchanged. The softening start temperature is maintained at about 1040℃, the softening range is about 110℃, the melting start temperature is about 1230℃, and the melting range is about 175℃; this shows that inlaying return ore has little effect on the soft melting performance of the sintered ore.

[0115] In summary, in order to obtain better sintering yield and sintering strength at the same time, the return ore inlay ratio should be 40% to 100%; preferably, the return ore inlay ratio is 40% to 80%; further, the return ore inlay ratio is 80%.

[0116] Effect Example 3 Effect of different return ore inlay ratios on sintering process indicators

[0117] The 800mm thick sintered material layer is evenly divided into three layers: upper, middle and lower. The return ore is embedded in different layers, and the embedding ratio is controlled to be 100%. The particle size of the return ore is 3-7mm.

[0118] 1. The influence of the return ore embedding position on the sintering output

[0119] Depend on Fig. 20 and Fig.21It can be seen that when the return ore is inlaid close to the lower part and the lower middle part, the sintering speed and utilization coefficient are better than the upper part, the sintering speed is increased by 2mm / min, and the sintering utilization coefficient is increased by an average of 0.1t / m2·h; the position priority is: lower middle > lower > middle > upper middle > upper, because the return ore is inlaid at the lower part, which is beneficial to improve the air permeability of the lower part of the material layer and reduce the influence of excessive moisture in the lower part of the material layer on the sintering effect during ventilation sintering.

[0120] Depend on Fig. 22 It can be seen that when the return ore is embedded in the middle or upper-middle part, the firing rate is slightly higher than that in the lower part, but overall the firing rate does not change much.

[0121] 2. The influence of the return ore embedding position on the sintering strength

[0122] Depend on Fig.23 It can be seen that when the return ore embedding position is close to the lower part, the strength of the sintered ore decreases slightly. This may be due to the faster sintering speed and shorter high-temperature holding time, which leads to a decrease in strength. The position priority is: upper middle > upper > lower middle > middle > lower; Fig.24 It can be seen from the anti-wear test that the position priority of the anti-wear index is lower middle = lower > upper middle = upper > middle.

[0123] Depend on Fig.25 It can be seen that when the return ore inlay position is in the middle and upper part, there are fewer sintered ores with a particle size of <10 mm, and the particle size of the sintered ore is more uniform, followed by the middle and middle and lower positions.

[0124] 3. Influence of the return ore embedding position on the metallurgical properties of sintered ore

[0125] Depend on Fig.26 It can be seen that, on the whole, the return ore is embedded in the lower part of the sintering material layer, and the reducibility of the sintered ore is higher than that of the sintered ore only embedded in the upper part. Among them, the reducibility is best when the return ore is embedded in the middle and lower parts. This is because the return ore is embedded in the lower part, which can alleviate the poor air permeability caused by the over-humidification of the lower layer of the material due to ventilation, which is conducive to the ore powder being easier to contact with air to generate Fe2O3 during the sintering process, thereby improving the reducibility.

[0126] Depend on Fig. 27 It can be seen that after the return ore is inlaid in different positions, the softening performance and melting dripping performance of the sintered ore do not change significantly, the softening start temperature remains at about 1060°C, the softening range is about 98°C, the melting start temperature is about 1230°C, and the melting range is about 180°C. This shows that changing the position of the inlaid return ore has no obvious effect on the soft melting performance of the sintered ore.

[0127] In summary, if the sintering output, sintering strength and metallurgical properties of sintered ore are to be optimized, the best effect is achieved when the return ore embedding position is in the middle and lower part.

[0128] The above are only preferred embodiments of the present invention. It should be noted that the above preferred embodiments should not be regarded as limiting the present invention, and the protection scope of the present invention should be based on the scope defined by the claims. For ordinary technicians in this technical field, several improvements and modifications can be made without departing from the spirit and scope of the present invention, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A sintering process for returning ore, comprising the following steps: Batching, first-mixing, second-mixing granulation, material distribution, ignition, sintering, crushing and cooling, screening, and sintered ore index detection; characterized in that the base material prepared in the batching includes: in parts by weight, return ore (30-35) parts, coke powder (3.5-4.0) parts, quicklime (5.5-7.0) parts, dolomite powder (2.0-3.0) parts, and mixed powder (51-53) parts; wherein, before the first-mixing step, the return ore is screened, and the return ore with a particle size of 0-3 mm is first mixed with the coke powder, quicklime, dolomite powder, and mixed powder for first and second-mixing granulation to obtain a second-mixed sintering material, and then the return ore with a particle size of 3-5 mm is mixed with the second-mixed sintering material, and then subsequent processes are carried out; the inlay ratio of the return ore is 40%-100%, and the inlay position of the return ore is the middle and lower layers of the sintering layer.

2. The ore-returning inlay sintering process according to claim 1, characterized in that: The mixed powder is composed of the following by weight percentage: 68% of fine powder, 19% of mineral powder, 11% of iron-containing recycled materials, and 2% of steel slag.

3. The ore-returning inlay sintering process according to claim 1, characterized in that: The chemical composition of the sintered ore of the base material is: basicity R is (2.2-2.7), TFe (47.0-50.0)%, SiO2 (5.0-5.8)%, CaO (13-17)%, MgO (2.6-3.0)%, Al2O3 (2.5-3.5)%, S (0.07-0.12)%, P (0.06-0.12)%, TiO2 (4.0-5.8)%, V2O5 (0.3-0.45)%.

4. The ore-returning inlay sintering process according to claim 1, characterized in that: The amount of water added during the first mixing process is 7% of the mass of the base material.

5. The ore-returning inlay sintering process according to claim 1, characterized in that: The thickness of the sintering material layer during the sintering process is 750-800 mm.

6. The ore-returning inlay sintering process according to claim 1, characterized in that: During the ignition process, the ignition temperature is 1150° C., the ignition time is 1 min, and the ignition negative pressure is 11 kPa.

7. The ore-returning inlay sintering process according to claim 1, characterized in that: The sintering negative pressure during the sintering process is 16 kPa.

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