Determinación de tiourea para el proceso de lixiviación de metales preciosos por titulación con yodato

Translated title of the contribution: Thiourea determination for the precious metals leaching process by iodate titration

D. Calla-Choque, F. Nava-Alonso

Research output: Contribution to journalArticle

Abstract

The thiourea leaching process for precious metals recovery has been studied as an alternative process to cyanidation. The accurate and simple determination of thiourea is important to guarantee the efficiency of the process and to evaluate the thiourea consumption during the gold and silver leaching from minerals; however, there is not, until now, a trustable method to determine the thiourea concentration for the high levels used in the extractive metallurgy industry. The present work, performed at CINVESTAV Saltillo, studies thermodynamically and experimentally, the thiourea determination by iodate titration in the search of a precise technique appropriate for the high thiourea concentrations used in the leaching of precious metals. The thiourea titration by iodate in acid media permits the precise determination of high thiourea concentrations (up to 10,000 ppm). The acidification of thiourea (CS(NH2)2) produces protonated thiourea (HCS(NH2)+2) which reacts with iodate to form the protonated formamidine disulfide ([CS(NH2)2]2+ 2). The presence of oxidant ions like cupric or ferric ions can oxidize the thiourea to formamidine disulfide (FDS2+), reducing the leaching strength of the solution. The iodate titration determines only the free thiourea that is available for the leaching of precious metals, and not the metal-thiourea complexes. When zinc dust is added to the solution before the titration, zinc reduces FDS2+ by regenerating the thiourea.

Original languageSpanish
Pages (from-to)275-284
Number of pages10
JournalRevista Mexicana de Ingeniera Quimica
Volume19
Issue number1
DOIs
StatePublished - 1 Jan 2020

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Iodates
Thiourea
Thioureas
Precious metals
Titration
Leaching
Disulfides
Zinc
Extractive metallurgy
Ions
Metal recovery
Acidification

Cite this

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title = "Determinaci{\'o}n de tiourea para el proceso de lixiviaci{\'o}n de metales preciosos por titulaci{\'o}n con yodato",
abstract = "The thiourea leaching process for precious metals recovery has been studied as an alternative process to cyanidation. The accurate and simple determination of thiourea is important to guarantee the efficiency of the process and to evaluate the thiourea consumption during the gold and silver leaching from minerals; however, there is not, until now, a trustable method to determine the thiourea concentration for the high levels used in the extractive metallurgy industry. The present work, performed at CINVESTAV Saltillo, studies thermodynamically and experimentally, the thiourea determination by iodate titration in the search of a precise technique appropriate for the high thiourea concentrations used in the leaching of precious metals. The thiourea titration by iodate in acid media permits the precise determination of high thiourea concentrations (up to 10,000 ppm). The acidification of thiourea (CS(NH2)2) produces protonated thiourea (HCS(NH2)+2) which reacts with iodate to form the protonated formamidine disulfide ([CS(NH2)2]2+ 2). The presence of oxidant ions like cupric or ferric ions can oxidize the thiourea to formamidine disulfide (FDS2+), reducing the leaching strength of the solution. The iodate titration determines only the free thiourea that is available for the leaching of precious metals, and not the metal-thiourea complexes. When zinc dust is added to the solution before the titration, zinc reduces FDS2+ by regenerating the thiourea.",
keywords = "Formamidine disulfide, Iodate titration, Precious metals leaching, Thiourea determination",
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Determinación de tiourea para el proceso de lixiviación de metales preciosos por titulación con yodato. / Calla-Choque, D.; Nava-Alonso, F.

In: Revista Mexicana de Ingeniera Quimica, Vol. 19, No. 1, 01.01.2020, p. 275-284.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Determinación de tiourea para el proceso de lixiviación de metales preciosos por titulación con yodato

AU - Calla-Choque, D.

AU - Nava-Alonso, F.

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N2 - The thiourea leaching process for precious metals recovery has been studied as an alternative process to cyanidation. The accurate and simple determination of thiourea is important to guarantee the efficiency of the process and to evaluate the thiourea consumption during the gold and silver leaching from minerals; however, there is not, until now, a trustable method to determine the thiourea concentration for the high levels used in the extractive metallurgy industry. The present work, performed at CINVESTAV Saltillo, studies thermodynamically and experimentally, the thiourea determination by iodate titration in the search of a precise technique appropriate for the high thiourea concentrations used in the leaching of precious metals. The thiourea titration by iodate in acid media permits the precise determination of high thiourea concentrations (up to 10,000 ppm). The acidification of thiourea (CS(NH2)2) produces protonated thiourea (HCS(NH2)+2) which reacts with iodate to form the protonated formamidine disulfide ([CS(NH2)2]2+ 2). The presence of oxidant ions like cupric or ferric ions can oxidize the thiourea to formamidine disulfide (FDS2+), reducing the leaching strength of the solution. The iodate titration determines only the free thiourea that is available for the leaching of precious metals, and not the metal-thiourea complexes. When zinc dust is added to the solution before the titration, zinc reduces FDS2+ by regenerating the thiourea.

AB - The thiourea leaching process for precious metals recovery has been studied as an alternative process to cyanidation. The accurate and simple determination of thiourea is important to guarantee the efficiency of the process and to evaluate the thiourea consumption during the gold and silver leaching from minerals; however, there is not, until now, a trustable method to determine the thiourea concentration for the high levels used in the extractive metallurgy industry. The present work, performed at CINVESTAV Saltillo, studies thermodynamically and experimentally, the thiourea determination by iodate titration in the search of a precise technique appropriate for the high thiourea concentrations used in the leaching of precious metals. The thiourea titration by iodate in acid media permits the precise determination of high thiourea concentrations (up to 10,000 ppm). The acidification of thiourea (CS(NH2)2) produces protonated thiourea (HCS(NH2)+2) which reacts with iodate to form the protonated formamidine disulfide ([CS(NH2)2]2+ 2). The presence of oxidant ions like cupric or ferric ions can oxidize the thiourea to formamidine disulfide (FDS2+), reducing the leaching strength of the solution. The iodate titration determines only the free thiourea that is available for the leaching of precious metals, and not the metal-thiourea complexes. When zinc dust is added to the solution before the titration, zinc reduces FDS2+ by regenerating the thiourea.

KW - Formamidine disulfide

KW - Iodate titration

KW - Precious metals leaching

KW - Thiourea determination

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JO - Revista Mexicana de Ingeniera Quimica

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