硅酸盐学报

熔融时间对模拟高放玻璃熔体中Ru析出物空间分布的影响

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徐立言 ¹^,² , 牛晨晨 ¹^,² , 徐凯 ¹^,² , 胡开文 ¹ , 贾子强 ¹ , 陈爱清 ³

硅酸盐学报 | 研究论文 2024,52(9): 3019-3026

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硅酸盐学报 |研究论文 2024 , 52 (9) : 3019 -3026

熔融时间对模拟高放玻璃熔体中Ru析出物空间分布的影响

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徐立言¹^,², 牛晨晨¹^,², 徐凯¹^,², 胡开文¹, 贾子强¹, 陈爱清³

作者信息

^1．武汉理工大学硅酸盐建筑材料国家重点实验室，武汉 430070

^2．中国核电工程有限公司，武汉理工大学玻璃固化技术联合实验室，北京 100840

^3．三峡大学分析测试中心，湖北宜昌 443002

通讯作者:

徐凯（1982—），男，博士，研究员。

作者简介:

徐立言（1999—），男，硕士研究生。

Study on the Influence of Melting Time on the Spatial Distribution of Ru Precipitates in Simulated High-Level Waste Glass Melts

Liyan XU¹^,², Chenchen NIU¹^,², Kai XU¹^,², Kaiwen HU¹, Ziqiang JIA¹, Aiqing CHEN³

Affiliations

^1.State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology, Wuhan 430070, China

^2.CNPE-WHUT Joint Laboratory of Nuclear Waste Vitrification Technology, Beijing 100840, China

^3.Analysis and Testing Center, China Three Gorges University, Yichang 443002, Hubei, China

Corresponding Author:

XU Kai (1982—), male, Ph.D., Professor. E-mail: kaixu@whut.edu.cn

XU Liyan (1999-), male, Master candidate. E-mail: 2636843456@qq.com

出版时间: 2024-09-20 doi: 10.14062/j.issn.0454-5648.20240168

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摘要

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陶瓷电熔炉技术是工业化应用最为广泛的高放废液玻璃固化处理技术，然而在其玻璃固化过程中低溶解度、高导电率的铂系金属（Ru、Rh及Pd）沉积问题是限制其发展的问题之一。本工作将1%（质量分数）RuO₂与模拟简化高放玻璃粉末在1200 ℃熔融制得铂系金属掺杂玻璃固化体样品，利用XRD与SEM表征Ru析出物的物相及微观形貌，并利用XRM分析Ru析出物在玻璃熔体中的分布特征及尺寸变化规律。结果表明Ru主要以RuO₂的物相析出，并伴随有少量Ru单质；样品中析出物颗粒体积分数随熔融时间延长而增加，而析出物团聚体平均尺寸随熔融时间呈现先增大后较小的趋势；此外，析出物在样品中的空间分布呈底层多、表层少的规律，底层析出物颗粒体积分数随熔融时间延长而增加，且其沉降速率随熔融时间延长而减小。

关键词

高放废液 / 玻璃固化 / 铂系金属 / 空间分布 / 沉积

Abstract

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Introduction

Platinum group metals (PGM), including ruthenium (Ru), rhodium (Rh), and palladium (Pd) are enriched in high-level liquid waste (HLLW) during the reprocessing of spent nuclear fuels. Vitrification is currently the only practical technology to immobilize HLLW. However, the high density and low solubility of PGM in glass cause them to settle down during vitrification process, resulting in the increased viscosity and conductivity of the glass melt at the bottom of the melter. This would potentially lead to concerned issues such as blockages in the discharge port and damage of electrodes. Therefore, understanding the deposition of PGM during vitrification is quite crucial in the management of HLLW. However, few research focused on the deposition process and the spatial distribution of PGM particles in glass melts. Thus, this work took Ru as the representative of PGM and investigated spatial distribution of Ru precipitates in glass melts.

Methods

A simplified simulated waste glass with the composition of 50.00%SiO₂-18.89%B₂O₃-2.79%Li₂O-5.00%CaO-13.30%Na₂O-6.68%Al₂O₃-3.34%ZrO₂ (mass fraction) was formulated. Batches were thoroughly mixed and placed in corundum crucibles, and then melted at 1200 ℃ for 1 h in a muffle furnace. The molten glass was quenched in air and then crushed to obtain the glass frits with the size smaller than 70 μm. Subsequently, glass frits and additional 1.00%RuO₂ (mass fraction) were then fully mixed. 3 g of mixtures was placed in a corundum crucible with a lid to prevent Ru volatilization, and remelted at 1200 ℃ for 0.5 h, 1 h, 2 h and 4 h, respectively, and then annealed at 500 ℃ for 2 h to release the thermal stress.

XRD was used to analyze the precipitated crystalline phases of the Ru-containing glasses. SEM-EDS was utilized to examine the morphology of Ru precipitates in glass samples and determine the distribution density of Ru precipitates particles in agglomerates. The glass samples were then cut into blocks with the size of 7 mm ×7 mm ×6 mm, and XRM was applied to detect the content of Ru precipitates, as well as changes in the size and quantity of agglomerates.

Result and discussion

XRD analysis suggested that RuO₂ and Ru precipitated from the glasses in different melting durations. SEM showed both RuO₂ and Ru formed the agglomerates, but RuO₂ agglomerates exhibited higher content and the larger sizes compared to Ru agglomerates. Through calculating the distribution density of RuO₂ particles in the agglomerates, it was determined that RuO₂ particles in the agglomerates coarsened and the RuO₂ agglomerates became more compact as the melting time increased.

Results from SEM and XRM indicate that RuO₂ particles aggregated into a larger size (~20 μm) in the short-time stage (t <1 h), and the content of precipitated RuO₂ and Ru increased rapidly and reached to its added level. In the middle-time stage (1 h< t <2 h), the coalescence of the agglomerates occurred and aggregated to a much larger size (>130 μm). Consequently, the number density of agglomerates decreased, whereas the volume fraction of agglomerates remained relatively stable. In the long-time stage (2 h< t <4 h), the agglomerates turn to the denser one. This led to the increase of particles distribution density and the decrease of agglomerates size. At this stage, the number density of agglomerates remained even.

The three-dimensional images reconstructed from XRM were segmented into 12 layers from top to bottom. The analysis focused on the content of Ru precipitates in each layer of glasses melted for different durations. The samples were categorized into three regions: the surface layer (0~1.5 mm), middle layer (1.5~5 mm), and bottom layer (5~6 mm). The content of precipitated particles in the bottom layer were notably larger compared to those in the middle and surface layers, when the melting time was the same. Furthermore, the content of precipitated particles in the bottom layer increased with prolonged melting time, and approximately 50% of the precipitates settled down in the crucible bottom after 4 h melting. The rate of precipitates deposition decreased as the melting time increased.

Conclusion

Ruthenium primarily precipitates as the form of RuO₂ particles in the simulated waste glass. As the melting time is prolonged, the Ru precipitates undergo various processes, including formation of agglomerates, coalescence between agglomerates, and densification of agglomerates. The content of precipitates in the bottom layer was larger than those in the middle and surface layers. The volume fraction of precipitates in the bottom layer increases with extended melting time, and the rate of deposition of precipitates decreases as melting time increases.

Key words

high-level liquid waste / vitrification / platinum group metals / spatial distribution / deposition

引用本文

徐立言, 牛晨晨, 徐凯, 胡开文, 贾子强, 陈爱清. 熔融时间对模拟高放玻璃熔体中Ru析出物空间分布的影响. 硅酸盐学报, 2024 , 52 (9) : 3019 -3026 . DOI: 10.14062/j.issn.0454-5648.20240168

Liyan XU, Chenchen NIU, Kai XU, Kaiwen HU, Ziqiang JIA, Aiqing CHEN. Study on the Influence of Melting Time on the Spatial Distribution of Ru Precipitates in Simulated High-Level Waste Glass Melts[J]. Journal of the Chinese Ceramic Society, 2024 , 52 (9) : 3019 -3026 . DOI: 10.14062/j.issn.0454-5648.20240168

基金

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国家自然科学基金(U2241290)

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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.0454-5648.20240168

接收时间：2024-02-29
首发时间：2026-10-22
出版时间：2024-09-20

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收稿日期：2024-02-29
修回日期：2024-03-29

基金

国家自然科学基金(U2241290)

作者信息

^1．武汉理工大学硅酸盐建筑材料国家重点实验室，武汉 430070

^2．中国核电工程有限公司，武汉理工大学玻璃固化技术联合实验室，北京 100840

^3．三峡大学分析测试中心，湖北宜昌 443002

通讯作者:

徐凯（1982—），男，博士，研究员。

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https://castjournals.cast.org.cn/joweb/gsyxb/CN/10.14062/j.issn.0454-5648.20240168

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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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