Noncyanide leaching of an auriferous pyrite ore from Ecuador

Direct leach approaches to Platinum Group Metal (PGM) ores and concentrates: A review

“…One of the important features of thiourea [SC(NH 2 ) 2 , or Tu] gold dissolution is that the leaching can be performed in acidic media, enabling the use of soluble oxidizing agents such as ferric salts (Eq. (44)) (Li and Miller, 2006;Munoz and Miller, 1999). The leach reaction is rapid and according to Prasad et al (1991), gold extractions of up to 99% can be achieved in acidic conditions (solution pH of about 1.4) within 10-15 min.…”

Investigate of Effective Factors on Extraction of Silver from Tailings of Lead Flotation Plant Using Thiourea Leaching

“…Cyanidation has become the most popular method of gold and silver recycling from mineral resources because of the simplicity and economical reasons for more than a century (Wei et al, [1]; Yang et al, [2]- [4]). Being toxic and environmental restrictions may increase using of new reagents such as halogens (Gurung et al, [5]), thiocyanide (Kholmogorov et al, [6]), thiosulfate (Abbruzzese et al, [7]; Ficeriová et al, [8]; Hiskey and Atluri, [9]) and thiourea are alternatives (Çelik, [10]; Chen et al, [11]; De Andrade Lima and Hodouin, [12]; Ficeriová et al, [13]; Hilson and Monhemius, [14]; Kononova et al, [15]; Lacoste et al, [16]; Li and Miller, [17]; Muir and Aylmore, [18]; Muñoz and Miller, [19]; Murthy, [20] [21]). Some of these methods are not only ecofriendly but also their leaching rates are higher than the conventional cyanidation method (Chen et al, [11]; Ficeriová et al, [16]; Agma et al, [22]; Groenewald, [23]).…”

Using Electrochemical Impedance Spectroscopy to Investigate Gold Dissolution in Thiourea and Thiocyanate Acid Solutions

“…Due to the toxicity of cyanide and associated environment concerns, considerable efforts have been made to search for alternative gold lixiviants. (2)(3)(4)(5)(6)(7)(8). Thiourea is proven to provide fast initial gold leaching rates and lower toxicity (9)(10)(11)(12)(13), but is unstable and easily decomposes into other complex compounds, which passivate the gold surface and slow down the gold dissolution rate (14).…”

“…The application of this technique to understand gold dissolution in the presence of thiourea has been reported in recent years (20). A number of studies of gold anodic oxidation in thiocyanate solution have been reported (7,(15)(16)(17)(18)21). No EIS characterization of gold in the presence of thiourea and thiocyanate has been reported.…”