NaOH-HF stepwise extraction method for extracting high-purity calcium fluoride from fluoride-containing sludge: A sustainable approach

IF 9 1区工程技术 Q1 ENGINEERING, CHEMICAL Separation and Purification Technology Pub Date : 2025-08-30 Epub Date: 2025-03-09 DOI:10.1016/j.seppur.2025.132437

Jiangjie Fang , Huifen Yang , Pu Gao , Qiwei Sun , Dong Lin , Zhenguo Song

{"title":"NaOH-HF stepwise extraction method for extracting high-purity calcium fluoride from fluoride-containing sludge: A sustainable approach","authors":"Jiangjie Fang , Huifen Yang , Pu Gao , Qiwei Sun , Dong Lin , Zhenguo Song","doi":"10.1016/j.seppur.2025.132437","DOIUrl":null,"url":null,"abstract":"<div><div>Fluoride-containing sludge (FCS), a hazardous waste, poses significant environmental challenges, while the growing shortage of fluorite minerals makes the recovery of CaF<sub>2</sub> from FCS an attractive solution. This study presents a novel two-step extraction process for the purification and recovery of CaF<sub>2</sub>. After optimizing reagent formulations, the process involves an initial reaction with 6 % NaOH, followed by a second reaction with 3 % HF. Under optimal conditions—3h reaction time, 40 °C, solid-to-liquid ratio of 1:2.5, and stirring speed of 250 r/min for the first stage, and 1 h reaction time with identical conditions for the second stage—a CaF<sub>2</sub> product with 70.30 % purity and 90.3 % recovery was achieved. X-ray diffraction (XRD) analysis confirmed that the reagents transformed impurities in the sludge into more soluble phases. Thermodynamic analysis further validated the feasibility of the chemical extraction process. The cost analysis showed that the total extraction cost was 758.125 CNY/t, yielding a profit of 686.675 CNY/t. In conclusion, this process is an efficient and cost-effective method for defluorination and CaF<sub>2</sub> recovery in the fluoride chemical industry, providing both theoretical and practical support for FCS purification and impurity removal.</div></div>","PeriodicalId":427,"journal":{"name":"Separation and Purification Technology","volume":"364 ","pages":"Article 132437"},"PeriodicalIF":9.0000,"publicationDate":"2025-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Separation and Purification Technology","FirstCategoryId":"5","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S1383586625010342","RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"2025/3/9 0:00:00","PubModel":"Epub","JCR":"Q1","JCRName":"ENGINEERING, CHEMICAL","Score":null,"Total":0}

引用次数: 0

Abstract

Fluoride-containing sludge (FCS), a hazardous waste, poses significant environmental challenges, while the growing shortage of fluorite minerals makes the recovery of CaF₂ from FCS an attractive solution. This study presents a novel two-step extraction process for the purification and recovery of CaF₂. After optimizing reagent formulations, the process involves an initial reaction with 6 % NaOH, followed by a second reaction with 3 % HF. Under optimal conditions—3h reaction time, 40 °C, solid-to-liquid ratio of 1:2.5, and stirring speed of 250 r/min for the first stage, and 1 h reaction time with identical conditions for the second stage—a CaF₂ product with 70.30 % purity and 90.3 % recovery was achieved. X-ray diffraction (XRD) analysis confirmed that the reagents transformed impurities in the sludge into more soluble phases. Thermodynamic analysis further validated the feasibility of the chemical extraction process. The cost analysis showed that the total extraction cost was 758.125 CNY/t, yielding a profit of 686.675 CNY/t. In conclusion, this process is an efficient and cost-effective method for defluorination and CaF₂ recovery in the fluoride chemical industry, providing both theoretical and practical support for FCS purification and impurity removal.

Abstract Image

查看原文

微信好友朋友圈 QQ好友复制链接

本刊更多论文

NaOH-HF分步萃取法从含氟污泥中提取高纯氟化钙的可持续途径

含氟污泥（FCS）是一种危险废物，对环境构成重大挑战，而萤石矿物的日益短缺使得从含氟污泥中回收CaF2成为一种有吸引力的解决方案。本研究提出了一种新的两步萃取工艺来提纯和回收CaF2。在优化试剂配方后，该过程包括6 % NaOH的初始反应，然后是3 % HF的第二次反应。在反应时间3h，反应温度40 °C，料液比1:25 .5，一级搅拌速度250 r/min，二级反应时间1 h，反应条件相同的条件下，可得到纯度为70.30 %，回收率为90.3 %的CaF2产品。x射线衍射（XRD）分析证实，这些试剂将污泥中的杂质转化为更易溶解的相。热力学分析进一步验证了化学萃取工艺的可行性。成本分析表明，总提取成本为758.125元/t，利润为686.675元/t。综上所述，该工艺是一种高效、经济的氟化工脱氟和CaF2回收方法，为FCS净化和除杂提供了理论和实践支持。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

求助全文

约1分钟内获得全文去求助

来源期刊

Separation and Purification Technology 工程技术-工程：化工

CiteScore

14.00

自引率

12.80%

发文量

2347

审稿时长

43 days

期刊介绍： Separation and Purification Technology is a premier journal committed to sharing innovative methods for separation and purification in chemical and environmental engineering, encompassing both homogeneous solutions and heterogeneous mixtures. Our scope includes the separation and/or purification of liquids, vapors, and gases, as well as carbon capture and separation techniques. However, it's important to note that methods solely intended for analytical purposes are not within the scope of the journal. Additionally, disciplines such as soil science, polymer science, and metallurgy fall outside the purview of Separation and Purification Technology. Join us in advancing the field of separation and purification methods for sustainable solutions in chemical and environmental engineering.