Abstract:Based on the present material condition of N0.3 sintering plant of Magang, the effects of different basicitys and SiO 2 and MgO contents in sinter on production and quality of sinter are studied. The results show that, with increas ing the sinter basicitys And SiO 2 contents, the sinter strength is improved, but after increasing the MgO contents in sinter, all sinter technical-economic indexes are worsened., the sinter basicity should be 2.0, SiO 2 content should be 4.95%, MgO content should be Reduced to the best of its ability in practical production.
Alkalinity sinter, MgO and SiO 2 content directly affects the level of sinter ore grade, strength, yield and metallurgical properties. In order to understand the impact of their changes on sintering technology indicators, Ma On Shan steel Co., Ltd. (Magang) were different laboratory sintered MgO sinter, SiO 2 content and experiment with different levels of alkalinity.
1. Raw material composition and sintering process system
The iron content of the test was taken from the production site of the Hong Kong Raw Materials Plant and the Maanshan No. 3 Sintering Plant. The chemical composition is listed in Table 1. The sintering test was carried out on a Φ300mm sintering cup with a material layer height of 580 mm, an ignition negative pressure of 6 kPa, an ignition time of 1.5 min, and a sintered exhaust negative pressure of 12 kPa. After the sintered cake was cooled on the machine, it was subjected to drop and ISO drum test, and then sampled for chemical analysis and metallurgical performance test. Each set of tests was repeated several times under the same conditions, and the average of two tests within the allowable error range was the test result to ensure the reproducibility of the test results.
Table 1 Chemical composition analysis of iron-containing raw materials
Powder mine name | TFe | FeO | SiO 2 | CaO | Al 2 O 3 | MgO | TiO 2 | S | P | Burnt out |
Gu Jing | 57.41 | 0.50 | 12.09 | 0.823 | 1.15 | 0.299 | 0.225 | 0.012 | 0.250 | 2.25 |
CVRD powder | 65.28 | 0.23 | 3.74 | 0.355 | 0.78 | 0.089 | 0.054 | 0.012 | 0.019 | 0.72 |
Yang Jifen | 58.71 | 0.31 | 4.35 | 0.102 | 1.35 | 0.104 | 0.049 | 0.003 | 0.050 | 10.47 |
Tian Pu Le powder | 62.36 | 1.76 | 3.84 | 0.029 | 1.94 | 0.067 | 0.115 | 0.003 | 0.049 | 4.47 |
Chaina powder | 63.01 | 0.31 | 3.97 | 0.130 | 2.12 | 0.085 | 0.104 | 0.012 | 0.065 | 3.19 |
FTC powder | 66.01 | 0.31 | 3.10 | 0.078 | 0.89 | 0.043 | 0.118 | 0.99 | 0.029 | 1.22 |
MBR powder | 67.00 | 0.42 | 1.46 | 0.120 | 1.20 | 0.060 | 0.19 | 0.010 | 0.050 | 1.30 |
Second, the test plan
A total of 7 groups were performed in this trial. The ratio of the sintered iron-containing material used in the design is basically consistent with the current production mix ratio of the third sintering plant of Maanshan Iron & Steel Co., Ltd., mainly by the ratio of the higher content of SiO 2 and the addition of limestone and dolomite. The adjustment makes the alkalinity, MgO and SiO 2 content of the sinter meet the requirements of each test level. The levels of test factors for each group are shown in Table 2. The mix ratio and grouping of each group are shown in Table 3. The iron content of the mixture is 100%, and the fuel and flux percentages are externally matched.
Table 2 Levels of test factors in each group %
Group No | SiO 2 | R | MgO | Remarks |
1 | 4.95 | 1.85 | 2.10 | Baseline group |
2 | 4.95 | 1.65 | 2.10 | Low alkalinity |
3 | 4.95 | 2.05 | 2.10 | High alkalinity |
4 | 4.95 | 1.85 | 2.40 | High MgO content |
5 | 4.95 | 1.85 | 1.80 | Low MgO content |
6 | 4.80 | 1.85 | 2.10 | Low SiO 2 content |
7 | 5.15 | 1.85 | 2.10 | High SiO 2 content |
Table 3 Mixing ratio and grouping of the mixture %
Group No | Gu Jing | CVRD powder | Yang Jifen | Tian Pu Le powder | Chaina powder | FTC powder | dolomite | limestone |
1 | 13.6 | 30 | 12 | 11 | 17 | 16.4 | 10.09 | 7.10 |
2 | 13.2 | 30 | 12 | 11 | 17 | 16.8 | 10.06 | 4.87 |
3 | 14.0 | 30 | 12 | 11 | 17 | 16.0 | 10.13 | 9.38 |
4 | 13.7 | 30 | 12 | 11 | 17 | 16.3 | 11.80 | 6.20 |
5 | 13.5 | 30 | 12 | 11 | 17 | 16.5 | 8.40 | 7.99 |
6 | 11.7 | 30 | 12 | 11 | 17 | 18.3 | 10.11 | 6.50 |
7 | 16.2 | 30 | 12 | 11 | 17 | 13.8 | 10.07 | 7.92 |
Third, test results and analysis
The chemical composition of the sinter is listed in Table 4, and the results of the metallurgical properties test are shown in Table 5.
Table 4 Chemical composition of sinter ore %
Group No | TFe | FeO | SiO 2 | CaO | MgO | Al 2 O 3 | TiO 2 | S | P | C/S |
1 | 57.73 | 8.44 | 5.02 | 9.23 | 2.10 | 1.46 | 0.106 | 0.011 | 0.065 | 1.84 |
2 | 57.97 | 7.96 | 5.09 | 8.53 | 2.11 | 1.54 | 0.103 | 0.010 | 0.063 | 1.67 |
3 | 57.13 | 7.46 | 5.04 | 9.98 | 2.07 | 1.58 | 0.120 | 0.014 | 0.068 | 1.98 |
4 | 57.58 | 8.73 | 5.00 | 9.41 | 2.30 | 1.56 | 0.104 | 0.012 | 0.069 | 1.88 |
5 | 57.68 | 9.25 | 4.94 | 9.27 | 1.89 | 1.41 | 0.107 | 0.99 | 0.065 | 1.88 |
6 | 58.15 | 8.56 | 4.81 | 9.05 | 2.10 | 1.55 | 0.102 | 0.99 | 0.065 | 1.88 |
7 | 57.62 | 7.75 | 5.15 | 9.35 | 2.03 | 1.50 | 0.117 | 0.013 | 0.071 | 1.82 |
Table 5 Results of reduction, reduction pulverization and droplet performance test
Group No | Reducing powder test result /% | Degree of reduction (RI)/% for different reduction times | Start softening temperature Ts/°C | Start melting temperature Tm/°C | Start dropping temperature T D /°C | Highest pressure difference ΔPmax | Gas permeability index S/ | Drop amount M D | |||||||
RDI +6.3 | RDI +3.15 | RDI | 30min | 60min | 90min | 120min | 150min | 180min | |||||||
1 | 25.36 | 58.76 | 7.53 | 30.36 | 46.24 | 58.15 | 66.46 | 71.20 | 75.14 | 1108 | 1335 | 1495 | 4.609 | 418 | 41.5 |
2 | 23.56 | 54.92 | 8.37 | 28.39 | 44.90 | 55.52 | 60.96 | 68.47 | 71.98 | 1128 | 1324 | 1440 | 2.157 | 157 | 80.3 |
3 | 26.24 | 59.63 | 7.55 | 29.96 | 45.13 | 57.93 | 67.92 | 75.71 | 81.09 | 1115 | 1345 | 1520 | 3.530 | 342 | 1.5 |
4 | 28.09 | 61.79 | 6.68 | 28.88 | 43.32 | 54.14 | 63.75 | 69.75 | 74.13 | 1130 | 1330 | 1505 | 2.157 | 320 | 85.0 |
5 | 32.78 | 62.71 | 7.45 | 25.77 | 41.28 | 54.00 | 64.32 | 73.05 | 79.39 | 1082 | 1324 | 1465 | 4.707 | 339 | 79.1 |
6 | 26.41 | 59.55 | 7.40 | 24.79 | 39.51 | 51.44 | 61.78 | 70.52 | 78.06 | 1108 | 1310 | 1480 | 7.747 | 778 | 43.1 |
7 | 24.80 | 57.42 | 8.13 | 27.96 | 44.37 | 57.98 | 68.37 | 76.76 | 81.93 | 1126 | 1342 | 1510 | 3.138 | 197 | 41.4 |
(1) Influence of different sinter mineral alkalinity
Different sinter alkalinity levels were tested by Group 2, Group 1 and Group 3. It can be seen from the test results that when the SiO 2 content of the sinter is constant, the sintering productivity and the sinter strength index increase with the increase of alkalinity. When the alkalinity is increased from 1.65 to 2.05, the vertical sintering speed is slightly increased (from 18.78 mm/min to 19.51 mm/min), and the yield of sintered ore is increased (from 76.42% to 78.17%) to cause sintering. The productivity increased from 1.231 t/m 2 .h to 1.253 t/m 2 .h, and the strength index of the sintered ore was also improved, and the drum index was also increased from 65.39% to 67.88%. This is mainly because the calcium ferrite in the sinter binder phase is further developed after the alkalinity is increased. At the same time, as the sintering yield increases with the increase of alkalinity, the burning solid burning consumption of the ore mine decreases from 68.24kg to 66.65kg. The grade of sintered ore decreased from 57.97% to 57.13%.
With the increase of alkalinity, RDI +6.3 increased continuously, RDI +3.15 also increased, RDI -0.5 decreased, but the first and third groups were very close; the reduction improved significantly, the alkalinity increased by 0.1, and the RI 180min increased by nearly 3.2. %, the softening temperature did not change significantly, the melting and dropping temperatures continued to increase, and the amount of dripping gradually decreased.
(B) the effect of sinter SiO 2 content
The SiO 2 content test of the sintered ore was composed of the sixth group, the first group and the seventh group. Under certain conditions of sinter alkalinity, with the increase of SiO 2 content, the bonded phase of sinter increased and the strength index became better. When the content of sinter SiO 2 increased from 4.80% to 5.15%, the drum index increased from 64.80% to 67.70%, the increase was about 2.9 percentage points, and the sintering yield increased by 1 percentage point. The sintering productivity showed a downward trend, from 1.300 t/m 2 .h to 1.247 t/. The reason for the decrease in productivity is that when the binder phase of the sintered ore increases, the gas permeability of the sintering process deteriorates and the sintering speed decreases. In addition, this test is to meet the different levels of sinter SiO 2 content by adjusting the higher content of sulphide concentrate containing SiO 2 . Increasing the content of SiO 2 in sinter ore requires adding more concentrates, and the increase in fine powder rate also directly affects the productivity of sinter.
With the increase of SiO 2 content, the grade of sintered ore decreased from 58.15% to 57.62%. This is because the amount of high-silicon self-produced concentrate is increased in the raw materials, and the imported high-grade Brazilian FTC mine is reduced, and the ratio of limestone is also improved.
The SiO 2 content of the three groups 1 , 6, and 7 is from low to high, and the corresponding reduction pulverization and reduction indexes are basically similar, while the softening, melting and dropping temperatures are also increasing, and the T D -Ts and T D -T m intervals The difference is not large, the highest pressure difference and the gas permeability S value are continuously reduced, and there is no significant difference in the amount of dripping.
(III) Influence of MgO content in different sintered ores
From the fifth group, the first group and the fourth group, the different MgO content tests of the sintered ore were formed. From the test results, it is known that with the increase of MgO content, the sinter output and drum strength decrease, and the solid fuel consumption increases. When the sinter MgO content increased from 1.8% to 2.4%, the productivity decreased from 1.281t/m 2 .h to 1.240t/m 2 .h, and the sinter drum strength decreased from 67.07% to 65.67%; The fuel consumption increased from 68.04kg to 69.20kg. There are the following reasons for the deterioration of the technical indicators of sintering economy:
1. The decomposition of dolomite in the sintering process is an endothermic reaction, so it is unfavorable for the formation of new compounds after decomposition of MgO mineralization. Microscopic analysis found that many unreacted round granular MgO is formed around the periclase . The magnesium ferrite (MgO·Fe 2 O 3 ) is cemented in the liquid phase.
2. This sintering test and on-site production are all equipped with coarse-grained dolomite (only 40% of -4mm content), resulting in a large number of dolomite "white spots" in the sinter.
3. Dolomite and silicate minerals are often mixed together to form forsterite and calcium olivine. The crystals are fine, generally exist in the vitreous phase, and fine cracks are found in the glass phase. With the addition of dolomite, The sinter glass phase is greatly increased. 
4. In the dolomite, Mg ++ easily penetrates into the Fe 3 O 4 crystal lattice and stabilizes the Fe 3 O 4 mineral phase, which makes it difficult for Fe 3 O 4 to transform into Fe 2 O 3 to form calcium ferrite. The more MgO is added, the more More Mg ++ penetrates into the Fe 3 O 4 lattice, limiting the development of the calcium ferrite system.
It can be seen from Table 5 that as the MgO content increases, the reduction pulverization index slightly deteriorates, the degree of reduction decreases, and the softening, melting, and dropping temperatures gradually increase.
Fourth, the conclusion
(1) Under certain conditions of sinter SiO 2 content, with the increase of sinter alkalinity, the sintering productivity and sinter strength index can be improved, and the reduction pulverization index is improved. Therefore, under the condition that the alkalinity of the existing blast furnace materials is balanced, the third sintering plant of Maanshan Iron and Steel Co., Ltd. should be organized according to the alkalinity of 2.0 to meet the requirements of the iron ore plant for sinter minerals and quality.
(2) Increasing the SiO 2 content of the sinter can also increase the strength of the sinter, the remelting temperature of the sinter increases, and the other metallurgical properties have no obvious change, but at the same time, the sinter grade and productivity are decreasing. Therefore, under the current conditions, the sinter SiO 2 content should be stabilized at 4.95% to ensure the strength of the sinter.
(3) When the content of MgO increases, the technical and economic indicators of sintering deteriorate, and the reduction and reduction of sinter are slightly worse. It can be seen that under the premise of ensuring the fluidity of the blast furnace slag, the MgO content in the sintered ore should be reduced as much as possible.
Pin Load Selection Machines,Shoulder and Shoulder Muscle Exercise Machine,Sitting posture supine shoulder trainer,Gym Shoulder Pushing Trainer
kangerte , https://www.corertefit.com