復合粘結劑對球團高溫固結的影響及機理

韓鳳光; 楊濤; 趙賀喜; 汪名赫; 王毅璠; 龍紅明; 雷杰; 姜濤

doi:10.13374/j.issn2095-9389.2022.11.17.003

復合粘結劑對球團高溫固結的影響及機理

doi: 10.13374/j.issn2095-9389.2022.11.17.003

韓鳳光^{1, 2},
楊濤^3,,
趙賀喜³,
汪名赫³,
王毅璠³,
龍紅明^3, ,,
雷杰^3, ,,
姜濤¹

1.
中南大學資源加工與生物工程學院，長沙 410083
2.
寶鋼股份中央研究院梅鋼技術中心，南京 210039
3.
安徽工業大學冶金工程學院，馬鞍山 243032

基金項目: 國家自然科學基金資助項目（52174290）；安徽省自然科學基金杰出青年資助項目（2208085J19）

詳細信息

通訊作者:
龍紅明, E-mail: yaflhm@126.com

雷杰, E-mail: leijie@ahut.edu.cn

中圖分類號: TQ132.32
計量
- 文章訪問數: 323
- HTML全文瀏覽量: 130
- PDF下載量: 102
- 被引次數: 0
出版歷程
- 收稿日期: 2022-11-17
- 網絡出版日期: 2023-01-31
- 刊出日期: 2023-09-25

Effects and mechanism of composite binder on high-temperature consolidation of pellets

HAN Fengguang^{1, 2},
YANG Tao^3
,,
ZHAO Hexi³,
WANG Minghe³,
WANG Yifan³,
LONG Hongming^{3
, ,},
LEI Jie^{3
, ,},
JIANG Tao¹

1.
School of Minerals Processing and Bioengineering, Central South University, Changsha 410083, China
2.
Meigang Technology Center, Central Research Institute of Baosteel Corporation, Nanjing 210039, China
3.
School of Metallurgical Engineering, Anhui University of Technology, Maanshan 243032, China

More Information

Corresponding author: LONG Hongming, E-mail: yaflhm@126.com; LEI Jie, E-mail: leijie@ahut.edu.cn

摘要

摘要: 膨潤土是球團礦生產過程中的主要粘結劑，能顯著改善原料成球性、提升球團質量，但較高的SiO₂和Al₂O₃含量會造成煉鐵生產渣量增加。添加少量有機粘結劑替代部分膨潤土已成為改善球團性能的必要手段。本文考察了有機粘結劑P替代部分膨潤土對球團高溫強度的影響，結合激光閃射法和熱重法（TG）研究了有機粘結劑對磁鐵礦球團內部結構及傳熱、傳質的影響。結果表明，復合粘結劑可以替代部分膨潤土，適量有機組分的增加有利于預熱球、焙燒球強度的提升和球團的氧化。主要原因是有機粘結劑P經過高溫后熱解，并在球團內部形成適量孔隙，球團熱傳導系數降低，內部升溫梯度減緩，避免了球團表層因過快氧化結晶而形成致密的氧化層。同時，細小的孔隙有利于氧氣進入球團內部，促進Fe₃O₄氧化成Fe₂O₃，氧化分數$ f $_TGA隨著有機粘結劑P的添加而逐漸升高，由90.80%提至92.17%。
- 球團 /
- 膨潤土 /
- 有機粘結劑 /
- 氧化固結 /
- 孔隙率
Abstract: Iron ore pellets have several substantial advantages, such as high iron grade, low harmful elements, low smelting slag, and low pollution in the production process. Rapidly developing the pelleting process and improving the quality of pellet ores is crucial for achieving the goals of carbon peaking and carbon neutrality in the steel industry. Bentonite, a major binder in the pellet ore production process, can significantly improve the sphericity of raw materials and enhance the pellet quality; however, the higher SiO₂ and Al₂O₃ content will cause an increase in the slag volume of ironmaking production. An organic binder has the advantages of low dosage and less harmful impurities, which can improve the pellet ore grade and the expansion rate of pellets. Thus, adding a small amount of organic binder to replace part of the bentonite is essential to improving the pellet performance. This study investigates the effect of organic binder P replacing part of bentonite on the high-temperature strength of pellets. The laser flash and thermogravimetric methods were employed to investigate the effects of organic binder on the internal structure, heat transfer, and mass transfer of pellets. The results indicated that bentonite was beneficial in reducing the porosity and high-temperature consolidation of pellets because it could promote the generation of a low-melting-point liquid phase. With increasing bentonite addition, the strength of preheated and roasted pellets increased, and the porosity decreased from 21.82% to 15.68% when bentonite addition increased from 1.1% to 2.0%. Thus, the composite binder could replace a part of the bentonite and significantly improve the strength of preheated and roasted pellets with increasing addition. Moreover, the organic binder P was pyrolyzed at a high temperature and formed pores inside the pellet, resulting in a lower thermal conductivity and a slower internal heating gradient. The thermal diffusivity reduced from 0.321 to 0.266 mm²·s^?1, and the heat transfer coefficient decreased gradually from 0.551 to 0.454 J·g^?1·K^?1. Thus, the formation of a dense oxide layer on the surface of the pellets owing to rapid oxidation was avoided, and the oxidation of hematite inside the pellets was promoted, thus enhancing the pellet strength. Moreover, the tiny pores facilitated oxygen transfer to the interior of the pellets and promoted the oxidation of Fe₃O₄ to Fe₂O₃. The oxidation fraction $ f $_TGA gradually increased from 90.80% to 92.17% with the addition of organic binder P.
- pellets /
- bentonite /
- organic binder /
- oxidation consolidation /
- porosity

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圖 1 有機粘結劑P的顆粒微觀形貌

Figure 1. Partical micromorphology of organic binder P

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圖 2 有機粘結劑P熱重分析和差熱分析

Figure 2. Thermogravimetric and differential thermal analysis of organic binder P

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圖 3 膨潤土F添加量對預熱、焙燒球強度的影響

Figure 3. Effect of bentonite F addition on the compressive strength of preheated and roasted pellets

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圖 4 不同膨潤土F添加量焙燒球團的顯微結構. (a) 1.1%F; (b) 1.2%F; (c) 1.3%F; (d) 1.4%F; (e) 2.0%F

Figure 4. Microstructure of roasted pellets with different bentonite F additions: (a) 1.1%F; (b) 1.2%F; (c) 1.3%F; (d) 1.4%F; (e) 2.0%F

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圖 5 復合粘結劑添加量對預熱、焙燒球強度的影響

Figure 5. Effect of compound binder P addition on the strength of preheated and roasted pellets

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圖 6 不同復合粘結劑添加量焙燒球團的顯微結構. (a) 1.2%F; (b) 1.2%F + 0.02%P; (c) 1.2%F + 0.024%P; (d) 1.2%F + 0.028%P

Figure 6. Microstructure of roasted pellets with different composite binder additions: (a)1.2%F; (b) 1.2%F + 0.02%P; (c) 1.2%F + 0.024%P; (d) 1.2%F + 0.028%P

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圖 7 添加復合粘結劑的磁鐵礦球團氧化未反應核收縮模型

Figure 7. Oxidized unreacted nuclear contraction model for magnetite pellets with the addition of a composite binder

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圖 8 激光閃射法示意圖

Figure 8. Schematic of laser flash method

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圖 9 不同復合粘結劑添加量焙燒球團的氧化區域.（a）球團外層（1—1.2% F，2—1.2% F + 0.02% P，3—1.2% F + 0.04% P，4—1.2% F + 0.06% P）;（b）球團內部（1—1.2% F，2—1.2% F + 0.02% P，3—1.2% F + 0.04% P，4—1.2% F + 0.06% P）

Figure 9. Oxidation zone of roasted pellets with different compound binder additions: (a) outer layer of pellets (1—1.2% F, 2—1.2% F + 0.02% P, 3—1.2% F + 0.04% P, 4—1.2% F + 0.06% P）; (b) inner layer of pellets (1—1.2% F, 2—1.2% F + 0.02% P, 3—1.2% F + 0.04% P, 4—1.2% F + 0.06% P)

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圖 10 不同有機粘結劑組分球團的TG曲線（a）和相應的氧化分數$ f $_TGA（b）

Figure 10. TG curves (a) and oxidation fraction $ f $_TGA (b) of pellets with different organic binder additions

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表 1 原料化學成分及配比（質量分數）

Table 1. Chemical composition and ratio of raw materials %

Iron ore	TFe	FeO	SiO₂	Al₂O₃	CaO	MgO	P₂O₅	S_x	LOI	Ratio
ore-A	65.15	24.89	4.95	1.66	0.40	0.54	0.01	0.08	?0.74	55
ore-B	65.46	25.83	3.76	0.63	1.02	1.62	0.10	0.20	?1.91	25
ore-C	65.75	26.50	6.57	0.84	0.30	0.48	0.01	0.05	?0.47	20

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表 2 原料的粒度分布及比表面積

Table 2. Particle size composition and specific surface area of raw materials

Iron ore	Particle size composition (mass fraction)/%			Specific surface area/(cm²?g^?1)
Iron ore	+74 μm	?74 μm～+45 μm	?45 μm	Specific surface area/(cm²?g^?1)
ore-A	6.0	15.2	78.8	1408
ore-B	0.5	4.7	94.8	1466
ore-C	6.4	13.3	80.3	1568

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表 3 膨潤土F物化特性

Table 3. Physical and chemical properties of bentonite F

Mass fraction of montmorillonite/%	Methylene blue adsorbed (per 100 g)/g	Water absorption (2 h)/%	Swelling coefficient/(mL·g^?1)	Colloid index (per 15 g)/mL
49.07	21.69	496	25	580

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表 4 不同膨潤土F添加量的焙燒球團孔隙度

Table 4. Porosity of roasted pellets with different bentonite F additions

Mass fraction of Bentonite F/%	Porosity/%
1.1	21.82
1.2	20.05
1.3	19.42
1.4	19.42
2.0	15.68

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表 5 復合粘結劑添加量的焙燒球團孔隙度

Table 5. Porosity of roasted pellets with different composite binder additions

Mass fraction of composite binder /%	Porosity/%
0.000	20.05
0.020	17.82
0.024	16.56
0.028	16.02

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表 6 復合粘結劑對球團的傳熱性能的影響

Table 6. Effect of composite binder on the heat transfer performance of pellets

Mass fraction of composite binder	Sample thickness/ mm	Sample density/ (g·cm^?3)	Thermal diffusivity/ (mm²·s^?1)	Heat transfer coefficient/ (W·m^?1·K^?1)	Specific heat capacity/ (J·g^?1·K^?1)
1.2% F	2.42	3.4	0.321	0.551	0.505
1.2% F + 0.02% P	2.46	3.3	0.309	0.530	0.504
1.2% F + 0.04% P	2.46	3.4	0.282	0.481	0.502
1.2% F + 0.06% P	2.46	3.4	0.266	0.454	0.502

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