Radionuclide Transfer in the Zirconium Oxychloride Production Process and the Radiation Effect in a Typical Chinese Enterprise

Shoulong Xu,Feng Yuan,Xiaogang Li,Liangying Tu,Qifan Wu

doi:10.3390/su11215906

Shoulong Xu, Feng Yuan + Show 3 more

Open Access

https://doi.org/10.3390/su11215906

Copy DOI

Journal: Sustainability	Publication Date: Oct 24, 2019
Citations: 2	License type: CC BY 4.0

Affiliation: University of South China, Tsinghua University

Abstract

The radiation impact on the environment from naturally-occurring radioactive materials in zircon sand is an important issue for zirconium product manufacturing enterprises. In this paper, a typical oxychloride production enterprise has been taken as an example to study the radiation effect and environmental pollution during the whole production process. The transfer and enrichment of radionuclides in zircon sand was studied by analyzing their concentrations in samples, such as products and wastes, which were sampled from every studied workshop, so that the dose rate in the environment and typical facility surfaces of each workshop could be measured. The study results show that the transfer and enrichment of radionuclides occur mainly in workshops of acidification, dissolution, concentration and crystallization. Silicon slag adsorbed some radionuclides, but most of the radionuclides in raw materials are transferred and enriched in waste acid by the concentration and crystallization process. Sludge and wastewater still contain a large quantity of radionuclides after treatment by wastewater treatment plants. This results in a significant increase in U-238 and Th-232 concentrations in river water near the main outlet. The average effective dose of all employees in the studied enterprises was 0.94 mSv, and workers from the wastewater treatment plants had the largest annual effective dose at 11 mSv.

Highlights

Zirconium oxychloride, as the basic raw material for zirconium metallurgy and chemical zirconium, is mainly produced by a chemical production process with zirconium sand [1]
Zircon sand is the only raw material, but this originates from different countries and places, and all the process links have their own discharged and produced products
The results show that the activity concentrations of U-238, Th-232 and Ra-226 in zirconium hydroxide are similar to those in zircon sand, indicating that radionuclides have not been transferred by alkali melting decomposition, washing, and the conversion processes

Summary

Introduction

As the basic raw material for zirconium metallurgy and chemical zirconium, is mainly produced by a chemical production process with zirconium sand [1]. The naturally-occurring radioactive materials in zircon sand are transferred and enriched with the chemical separation process, and discharged into the environment in the form of wastewater or solid waste [9,10]. ZZiirrccoonn ssaanndd,, ssooddiiuumm hhyyddrrooxxiiddee,, hhyyddrroocchhlloorriicc aacciidd aanndd wwaatteerr aarree tthhee mmaatteerriiaallss rreeqquuiirreedd ffoorr tthhee aacciidd––aallkkaallii zziirrccoonniiuumm ooxxyycchhlloorriiddee pprroodduuccttiioonn mmeetthhoodd. Zircon sand is the only raw material, but this originates from different countries and places, and all the process links have their own discharged and produced products. Based on the amount of used raw materials and yielded products, the irradiation effect and the irradiation exposure of workers were investigated and studied by the methods of both sampling and detection. The radiation dose rate of the public environment in the factory was detected

Radionuclides Transfer

External Dose Measurement and Dose Assessment

Findings

Conclusions