Preparation activated tailings by pH swing process: Towards yielding cemented tailings backfill and in-situ CO2 mineralization

IF 10.8 1区工程技术 Q1 CONSTRUCTION & BUILDING TECHNOLOGY

Cement & concrete composites Pub Date : 2024-09-21 DOI:10.1016/j.cemconcomp.2024.105767

Sijia Liu , Haiyun Gu , Ken Yang , Junyuan Guo , Kai Wu , Lijie Guo , Zhenghong Yang , Linglin Xu

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引用次数: 0

Abstract

In-situ CO₂ mineralization of tailings holds great potential for large-scale CO₂ sequestration, but its development is seriously limited by the low CO₂ conversion rate. This study proposed an innovative pH swing process to produce activated tailings through magnesium extraction from raw tailings and subsequent leachate precipitation. By the combination of activated tailings and high-belite calcium sulfoaluminate cement, a new type of cemented activated tailings backfill (CATB) was developed. The results demonstrate that 82.33 % of magnesium is extracted from raw tailings and precipitates in the form of Mg(OH)₂ serving as the dominating carbonation active phase during the pH swing process. Besides the aragonite forms in the carbonated cemented raw tailings backfill (CRTB), carbonated CATB also contains calcite, nesquehonite, and hydromagnesite. Substituting activated tailings for raw tailings results in a higher CO₂ absorption capability (ranging from 8.88 % to 14.17 % with various binder-to-tailings ratios). These indicate that the activated tailings have a promising application scenario in large scale in-situ CO₂ mineralization.

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通过 pH 值摆动法制备活性尾矿：实现胶结尾矿回填和就地二氧化碳矿化

尾矿原位二氧化碳矿化在大规模二氧化碳封存方面具有巨大潜力，但由于二氧化碳转化率低，其发展受到严重限制。本研究提出了一种创新的 pH 值摆动工艺，通过从原尾矿中提取镁，然后将浸出液沉淀，生产出活化尾矿。通过将活性尾矿与高白矾酸钙硫铝酸盐水泥相结合，开发出一种新型胶结活性尾矿回填（CATB）。结果表明，82.33% 的镁从原尾矿中提取出来，并在 pH 变化过程中以 Mg(OH)2 的形式沉淀，成为主要的碳化活性相。除了在碳化胶结原尾矿回填物（CRTB）中形成文石外，碳化 CATB 还含有方解石、菱镁矿和水镁石。用活性尾矿代替原尾矿可提高二氧化碳吸收能力（在不同的粘结剂与尾矿比率下，吸收能力从 8.88 % 到 14.17 % 不等）。这表明活化尾矿在大规模原地二氧化碳矿化方面具有广阔的应用前景。

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来源期刊

Cement & concrete composites 工程技术-材料科学：复合

CiteScore

18.70

自引率

11.40%

发文量

459

审稿时长

65 days

期刊介绍： Cement & concrete composites focuses on advancements in cement-concrete composite technology and the production, use, and performance of cement-based construction materials. It covers a wide range of materials, including fiber-reinforced composites, polymer composites, ferrocement, and those incorporating special aggregates or waste materials. Major themes include microstructure, material properties, testing, durability, mechanics, modeling, design, fabrication, and practical applications. The journal welcomes papers on structural behavior, field studies, repair and maintenance, serviceability, and sustainability. It aims to enhance understanding, provide a platform for unconventional materials, promote low-cost energy-saving materials, and bridge the gap between materials science, engineering, and construction. Special issues on emerging topics are also published to encourage collaboration between materials scientists, engineers, designers, and fabricators.