ISSN 2594-5327
55º Congresso anual — Vol. 55 , num. 1 (2000)
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A bibliographic search showed that thiourea have several applications in the fields of engineering and health, a fact reflected by the existence of the 866 american patents issued in the 1970-1999 period, at the same time 3964 scientific papers have been published in ISI indexed periodicals. In the domain of gold extractive metallurgy, the interest has grown in direct proportion to the efforts made in order to avoid polluting compounds and hazardous agents (mercury and cyanides). The issued patents and scientific developments are concentrated in the following directions: leaching with thiourea in acid medium in order to provide a leach liquor containing about 0.2 molar acid thiourea, alkaline leaching with thiourea containing Na₂CO₃ and Na₂S₂O₅, solvent extraction of gold from chloride solutions using thiourea derivatives and some other alternatives. If from experimental viewpoint and industrial application it is recognized the advance gained by the thiourea technology, from other hand thermodynamics of the thiourea-gold-water system continues underdeveloped. In view of this fact, the present paper tried to give new contributions to the thermodynamics of the thiourea-gold-water system. Potential-pH and activity-pH diagrams were calculated, constructed and analyzed for this system at 25 and 80°C. The diagrams obtained can explain the existing experimental data and will help henceforth in the planning of future research work in this scientific and technological line of interest.
A bibliographic search showed that thiourea have several applications in the fields of engineering and health, a fact reflected by the existence of the 866 american patents issued in the 1970-1999 period, at the same time 3964 scientific papers have been published in ISI indexed periodicals. In the domain of gold extractive metallurgy, the interest has grown in direct proportion to the efforts made in order to avoid polluting compounds and hazardous agents (mercury and cyanides). The issued patents and scientific developments are concentrated in the following directions: leaching with thiourea in acid medium in order to provide a leach liquor containing about 0.2 molar acid thiourea, alkaline leaching with thiourea containing Na₂CO₃ and Na₂S₂O₅, solvent extraction of gold from chloride solutions using thiourea derivatives and some other alternatives. If from experimental viewpoint and industrial application it is recognized the advance gained by the thiourea technology, from other hand thermodynamics of the thiourea-gold-water system continues underdeveloped. In view of this fact, the present paper tried to give new contributions to the thermodynamics of the thiourea-gold-water system. Potential-pH and activity-pH diagrams were calculated, constructed and analyzed for this system at 25 and 80°C. The diagrams obtained can explain the existing experimental data and will help henceforth in the planning of future research work in this scientific and technological line of interest.
Palavras-chave
thiourea, gold, leaching.
thiourea, gold, leaching.
Como citar
Silva, Flávio Teixeira da; Dutra, Achilles Junqueira Bourdort; Almendra, Ericksson Rocha e; Ogasawara, Tsuneharu.
EXTRACTION OF GOLD WITH THIOUREA: THERMODYNAMIC ANALYSIS OF THE THIOUREA-WATER AND THIOUREA-GOLD-WATER SYSTEMS,
p. 30-39.
In: 55º Congresso anual,
Rio de Janeiro, Brasil,
2000.
ISSN: 2594-5327, DOI 10.5151/2594-5327-C00744
