{"title":"Study on the radon exhalation rate of phyllite under thermal effects","authors":"","doi":"10.1016/j.psep.2024.09.076","DOIUrl":null,"url":null,"abstract":"<div><p>As a result of human underground mining activities, phyllite has been extensively reused to make raw ceramic materials and concrete aggregates. Building materials are a significant source of indoor radon, and radon gas emitted from phyllite poses radiation risks to humans. High temperatures can alter the structural properties of rocks, impacting radon exhalation. Thus, this study examined phyllite's radon exhalation rate after heat treatment ranging from 25 °C to 1000 °C. The effects of changes in pore structure and mineral composition on phyllite's radon exhalation were analyzed in detail using nuclear magnetic resonance (NMR), polarizing optical microscopy (POM), three-dimensional microscopy (3DM), and scanning electron microscopy (SEM). Results indicate that the radon exhalation rate initially increases and then decreases with rising temperature. This rate correlates positively with both total porosity and micropore porosity. Processes such as free water evaporation, pyrite oxidation, quartz phase transformation, and chlorite dehydroxylation within phyllite contribute to pore development and the movement of free radon within pore spaces. The highest total porosity and radon exhalation rate occur at 700 °C, measuring 8.6 % and 6.14 Bq/m<sup>2</sup>·h, respectively—4.30 times and 1.18 times higher than at 25 °C. Additionally, mineral decomposition and melting reduce pore connectivity and effective porosity, hindering radon migration. These findings offer guidance for assessing radon radiation risks and indoor radon potential in phyllite-based building materials.</p></div>","PeriodicalId":20743,"journal":{"name":"Process Safety and Environmental Protection","volume":null,"pages":null},"PeriodicalIF":6.9000,"publicationDate":"2024-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Process Safety and Environmental Protection","FirstCategoryId":"93","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0957582024012163","RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"ENGINEERING, CHEMICAL","Score":null,"Total":0}
引用次数: 0
Abstract
As a result of human underground mining activities, phyllite has been extensively reused to make raw ceramic materials and concrete aggregates. Building materials are a significant source of indoor radon, and radon gas emitted from phyllite poses radiation risks to humans. High temperatures can alter the structural properties of rocks, impacting radon exhalation. Thus, this study examined phyllite's radon exhalation rate after heat treatment ranging from 25 °C to 1000 °C. The effects of changes in pore structure and mineral composition on phyllite's radon exhalation were analyzed in detail using nuclear magnetic resonance (NMR), polarizing optical microscopy (POM), three-dimensional microscopy (3DM), and scanning electron microscopy (SEM). Results indicate that the radon exhalation rate initially increases and then decreases with rising temperature. This rate correlates positively with both total porosity and micropore porosity. Processes such as free water evaporation, pyrite oxidation, quartz phase transformation, and chlorite dehydroxylation within phyllite contribute to pore development and the movement of free radon within pore spaces. The highest total porosity and radon exhalation rate occur at 700 °C, measuring 8.6 % and 6.14 Bq/m2·h, respectively—4.30 times and 1.18 times higher than at 25 °C. Additionally, mineral decomposition and melting reduce pore connectivity and effective porosity, hindering radon migration. These findings offer guidance for assessing radon radiation risks and indoor radon potential in phyllite-based building materials.
期刊介绍:
The Process Safety and Environmental Protection (PSEP) journal is a leading international publication that focuses on the publication of high-quality, original research papers in the field of engineering, specifically those related to the safety of industrial processes and environmental protection. The journal encourages submissions that present new developments in safety and environmental aspects, particularly those that show how research findings can be applied in process engineering design and practice.
PSEP is particularly interested in research that brings fresh perspectives to established engineering principles, identifies unsolved problems, or suggests directions for future research. The journal also values contributions that push the boundaries of traditional engineering and welcomes multidisciplinary papers.
PSEP's articles are abstracted and indexed by a range of databases and services, which helps to ensure that the journal's research is accessible and recognized in the academic and professional communities. These databases include ANTE, Chemical Abstracts, Chemical Hazards in Industry, Current Contents, Elsevier Engineering Information database, Pascal Francis, Web of Science, Scopus, Engineering Information Database EnCompass LIT (Elsevier), and INSPEC. This wide coverage facilitates the dissemination of the journal's content to a global audience interested in process safety and environmental engineering.