Separation of Thorium from Zirconium Carbide Waste by Liquid–Liquid Extraction Using Tri-n-octylamine Solvent after Selective Acid Leaching

Abstract

Separation of thorium from zirconium carbide waste is reported. The waste typically contains zirconium, yttrium, uranium, and thorium, along with other impurities including rare earth elements (REEs), iron, calcium, aluminum, hafnium, and titanium. The first step in the separation was selective leaching of zirconium, uranium, and most other impurities with HNO 3 −HF, leaving thorium and REEs as insoluble fluorides. The effective parameters such as HNO 3 and HF concentrations, temperature, and time were optimized for achieving the maximum leaching of zirconium and the minimum leaching of thorium, using central composite design and a multiple response optimization algorithm. Thorium and REEs were leached from the residual solid with H 2 SO 4 , followed by their precipitation with ammonia, dissolution of the precipitate in HNO 3 , and extraction of thorium with tri-noctylamine−kerosene. The factors affecting the extraction of thorium were optimized with respect to HNO 3 , TOA, diluent, V org /V aq , and extraction time. Using the above sample preparation and extraction methods, thorium could be extracted with an efficiency of 95.6%.

Preparation of Quaternary Ammonium Separation Material based on Coupling Agent Chloromethyl Trimethoxysilane (KH-150) and Its Adsorption and Separation Properties in Studies of Th(IV)

“…Hassan S. Ghaziaskar successfully separated thorium from zirconium carbide waste residue by liquid-liquid extraction with trioctylamine after acid leaching. Chuanqin Xia designed and synthesized a ditriamide extractant, which has high selectivity for Th(IV) [9,10]. However, the extraction separation method requires meticulous operations such as shaking and phase separation, leading to long operation times and complex processes.…”

Selective Liquid–Liquid Extraction of Thorium(IV) from Rare-Earth Element Mixtures

“…In this study, we developed a straightforward, selective Th­(IV) extraction system that responds to the growing need for improved f-element separations. While promising Th­(IV) extraction results have been documented using a variety of creative methods, − these approaches remain limited by complex ligand synthetic procedures or extraction conditions requiring mixtures of additional chelators/ionic liquids, large extractant or nitric acid concentrations, or intricate protocols which may hinder practical application. Important to our approach is the utilization of the liquid–liquid extraction technique that is well-established for practical metal separation systems. , When this process is applied in industry, the aqueous metal solution generated from the dissolution of raw materials is mixed with an organic solvent containing chelator molecules designed to bind the metal ions of interest and extract them into the organic solvent.…”