硅酸盐学报

轻烧温度及球磨工艺对盐湖Mg（OH）₂制备镁砂烧结行为影响

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徐义彪 ¹ , 李亚伟 ¹ , 鄢文 ¹ , 周芬 ²

硅酸盐学报 | 研究论文 2024,52(9): 3003-3011

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硅酸盐学报 |研究论文 2024 , 52 (9) : 3003 -3011

轻烧温度及球磨工艺对盐湖Mg（OH）₂制备镁砂烧结行为影响

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徐义彪¹, 李亚伟¹, 鄢文¹, 周芬²

作者信息

^1．武汉科技大学，省部共建耐火材料与冶金国家重点实验室，武汉 430081

^2．武汉钢铁集团耐火材料有限责任公司，武汉 430082

作者简介:

徐义彪（1986—），男，博士，副教授。

Effects of Calcination Temperature and Ball Milling on Sintering Behavior of Magnesia from Salt Lake Mg(OH)₂

Yibiao XU¹, Yawei LI¹, Wen YAN¹, Fen ZHOU²

Affiliations

^1.The State Key Laboratory of Refractories and Metallurgy, Wuhan University of Science and Technology, Wuhan 430081, China

^2.Wugang Refractory Co. Ltd., Wuhan 430082, China

XU Yibiao (1986-), male, Ph.D., Associate Professor E-mail: xuyibiao@wust.edu.cn

出版时间: 2024-09-20 doi: 10.14062/j.issn.0454-5648.20230942

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摘要

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以盐湖氢氧化镁为原料，经650、750、850 ℃和950 ℃保温1 h轻烧，随后将轻烧MgO团聚体球磨（0.5、1.0、3.0、5.0、12.0、24.0 h）破碎，压制成型后于1600 ℃保温3 h制备了烧结镁砂，探讨了轻烧温度及球磨时间对镁砂显微结构及烧结性能的影响。结果表明：随轻烧温度由650 ℃升高到850 ℃，轻烧MgO团聚体内微晶平均尺寸由138 nm增加至180 nm，尽管微晶活性降低，但残余氢氧化镁减少，镁砂致密性呈增大趋势。轻烧温度升高至950 ℃，MgO微晶平均尺寸迅速增加至320 nm，活性大幅降低，镁砂晶粒尺寸及致密性显著降低。球磨工艺可以有效破坏轻烧MgO团聚体，其平均尺寸球磨0.5 h后由55.90 μm迅速降至2.69 μm，并随研磨时间增加至12 h逐渐降至1.72 μm，但进一步增加球磨时间团聚体尺寸基本不变。MgO团聚体的破坏减少了生坯中大气孔，提高了晶粒接触程度及传质速率，促进了晶粒长大及样品致密化。850 ℃制备的轻烧MgO球磨12 h压制的生坯，经1600 ℃保温3 h烧结，可制备平均晶粒30.4 μm，体积密度达3.42 g/cm³的致密镁砂。

关键词

盐湖氢氧化镁 / 烧结镁砂 / 轻烧温度 / 晶粒尺寸 / 致密化

Abstract

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Introduction

Magnesia, acted as a refractory material, is widely used in industrial metallurgical furnaces owing to its high refractoriness and excellent corrosion resistance to basic slag and metal melt. Generally, the fabrication of high-quality magnesia aggregates with high purity and high bulk densities (>3.40 g/cm³) plays a critical role in producing MgO-based refractories that show satisfying mechanical properties and corrosion resistance. In China, magnesite is mainly used as a raw material to produce sintered magnesia at high-temperature. while, as the generally coarse-grained of magnesite, it is difficult to produce high density magnesia even sintered at high temperatures, being due to the poor sintering property. As reported that the introduction of oxides additives such as TiO₂, Al₂O₃ ZrO₂, etc. could effectively promote the sintering of magnesia. However, the additives also resulted in a low melting phase formation, which significantly reduced the high-temperature performance of magnesia. In fact, besides magnesite, China also has abundant magnesium resources in salt lakes. Compared to magnesite, magnesia derived from salt lake owns the advantage of higher purity and without CO₂ emissions during the production process. In this work, magnesium hydroxide produced from salt lake was used as raw material to prepare the high-purity dense magnesia via a two-step method. Effects of calcination temperature and grinding time on the morphology and sintering activity of MgO were studied, microstructure and densification behavior of magnesia sintering at high-temperature were investigated also.

Methods

Magnesium hydroxide powder [Mg(OH)₂] was used as raw material. Firstly, it was lightly-burned to produce MgO when calcined at 650, 750, 850 ℃ and 950 ℃ with a holding time of 1 h and a heating rate of 5 ℃/min, repetitively. Secondly, the obtained powder was finely ground using mechanical ball milling for 0.5, 1.0, 3.0, 5.0, 12.0 ℃ and 24.0 h, respectively, here, zirconia balls acted as the media and anhydrous ethanol as solvent. Thirdly, the finely ground and dried powders were pressed into a green body with a size of Φ20 mm × 20 mm under a pressure of 100 MPa. Finally, the green body was sintered at 1 600 ℃ for 3 h to prepare the magnesia samples.

Results and discussion

Mg(OH)₂ would decompose into MgO agglomerates with crystallite and nano-pores when calcined at 650-850 ℃. The crystal size of MgO continuously increased with the increase of calcination temperature, and rapidly increased to 320 nm when temperature reached to 950 ℃. Correspondingly, the specific surface area of calcined MgO decreased with the increase of the temperature. In addition, a small amount of undecomposed Mg(OH)₂ still existed in lightly-burned MgO even treated at 750 ℃. When calcined at 850 ℃, the Mg(OH)₂ decomposed completely and the obtained MgO crystallite possessed high activity and best sintering properties. With the increase of grinding time, the number of MgO agglomerates decreased continuously and well disappeared when the grinding time reached to 12 h, and the average size of MgO agglomerates decreased to 1.72 μm. However, by further increasing the grinding time to 24 h, the average size of MgO agglomerates only decreased to 1.70 μm. The destruction of MgO aggregates could reduce the number of large pores and improve the contact between agglomerates in the green specimens, both could enhance the densification of the sintered specimens.

Conclusions

When the calcination temperature increased from 650 ℃ to 850 ℃, the sintering activity of crystallite in MgO agglomerations reduced slightly due to the increase of average size of MgO crystallite from 138 nm to 180 nm, while the density of sintered magnesia exhibited an increasing trend as content of residual Mg(OH)₂ in MgO agglomerations reduced. When calcined at 950 ℃, the sintering activity of the crystallite reduced dramatically and average size sharply increased to 320 nm, which obviously decreased the sintering activity and reduced the grain size and density of the specimens. The MgO agglomerations can be effectively crushed via the ball milling process, whose average size sharply reduced from 55.90 to 2.69 μm when ball milling for 0.5 h, and then this value decreased slowly to 1.72 μm when ball milling increasing to 12 h. However, a further increase of ball milling time would not produce the average size. The crush of MgO agglomerations could reduce the large pores in green compacts and enhanced the bonding between MgO crystallites, therefore enhancing the grain growth and densification of the specimens. When calcination temperature and milling time were 850 ℃ and 12 h, respectively, a dense magnesia with an average grain size of 30.4 μm and bulk density of 3.42 g/cm³ could be prepared when sintered at 1 600 ℃ for 3 h.

Key words

salt lake magnesium hydroxide / sintered magnesia / calcination temperature / grain size / densification

引用本文

徐义彪, 李亚伟, 鄢文, 周芬. 轻烧温度及球磨工艺对盐湖Mg（OH）₂制备镁砂烧结行为影响. 硅酸盐学报, 2024 , 52 (9) : 3003 -3011 . DOI: 10.14062/j.issn.0454-5648.20230942

Yibiao XU, Yawei LI, Wen YAN, Fen ZHOU. Effects of Calcination Temperature and Ball Milling on Sintering Behavior of Magnesia from Salt Lake Mg(OH)₂[J]. Journal of the Chinese Ceramic Society, 2024 , 52 (9) : 3003 -3011 . DOI: 10.14062/j.issn.0454-5648.20230942

基金

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青海省科技成果转化专项项目(2023-GX-10)
国家自然科学基金联合基金重点项目(U21A2058)

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2024年第52卷第9期

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文章信息

doi: 10.14062/j.issn.0454-5648.20230942

接收时间：2023-12-03
首发时间：2026-10-22
出版时间：2024-09-20

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收稿日期：2023-12-03
修回日期：2023-12-22

基金

青海省科技成果转化专项项目(2023-GX-10)

国家自然科学基金联合基金重点项目(U21A2058)

作者信息

^1．武汉科技大学，省部共建耐火材料与冶金国家重点实验室，武汉 430081

^2．武汉钢铁集团耐火材料有限责任公司，武汉 430082

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https://castjournals.cast.org.cn/joweb/gsyxb/CN/10.14062/j.issn.0454-5648.20230942

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2种不同金属材料的力学参数

科 Family	属数 Number of genus	种数 Number of species	占总种数比例 Percentage of total species (%)	属 Genus	种数 Number of species	占总种数比例 Percentage of total species (%)
鹅膏菌科Amanitaceae	2	11	5.26	鹅膏菌属 Amanita	10	4.78
小菇科 Mycenaceae	2	12	5.74	丝盖伞属 Inocybe	5	2.39
多孔菌科 Polyporaceae	8	14	6.70	蜡蘑属 Laccaria	5	2.39
红菇科 Russulaceae	3	23	11.00	小皮伞属 Marasmius	6	2.87
				小菇属 Mycena	11	5.26
				光柄菇属 Pluteus	5	2.39
				红菇属 Russula	17	8.13
				栓菌属 Trametes	5	2.39

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