Novel Aqueous Processing of the Reverted Turbine-Blade Superalloy for Rhenium Recovery

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• 作者：Rajiv Ranjan Srivastava ; Min-seuk Kim ; Jae-chun Lee
• 刊名：Industrial & Engineering Chemistry Research
• 出版年：2016
• 出版时间：July 27, 2016
• 年：2016
• 卷：55
• 期：29
• 页码：8191-8199
• 全文大小：537K
• 年卷期：0
• ISSN：1520-5045

文摘

A preliminary study on the hydrometallurgical recovery of rhenium from an engine-reverted superalloy, CMSX-4, was performed. The novelty of this work dealt with (i) the applicability of electro-generated Cl₂ in rhenium leaching and (ii) the maneuvering of the organic extractants based on the metal speciation in leach liquor. In a two-step HCl leaching, more than 98% rhenium was selectively leached in the presence of dissolved chlorine (Cl_2aq. and Cl_3aq.^–) in the second step, which was performed after a leaching of thermal-barrier and base-alloy elements in 4 mol L^–1 HCl. The leaching kinetics of rhenium indicated a shift from surface diffusion to a chemically controlled reaction with a variance in temperature from 313 to 353 K. The first use of phosphinic acid in molybdenum separation from rhenium in the leach liquor yielded a high separation value (β_Mo/Re = 839) using 0.067 mol L^–1 extractant; whereas the mixed-phosphine oxides showed a tremendous selectivity for separating rhenium from the base-metal impurities in the Mo-depleted solution. The extraction of rhenium increased from 9% to 98% with an increase in extractant concentration from 0.005 to 0.08 mol L^–1 in the organic phase. On a metal-to-metal basis, the recovery value of 93% rhenium as NH₄ReO₄ (9.5 g L^–1 Re in the solution) demonstrated the potential of the present process.