Mercurous salts as reductimetric reagents for titrations in alkaline medium

Selective Removal of Arsenic and Antimony from Pb-Ag Sulfide Concentrates by Alkaline Leaching: Thermodynamic and Kinetic Studies

“…This indirectly indicates their high reactivity as they are unstable. As2S3 and Sb2S3 are soluble in alkali polysulfides [25]. The dissolution reactions caused by the polysulfides formed from the dosed sulfur can be described by Equations ( 8)- (11).…”

Recovery of gallium and vanadium from gasification fly ash

“…Combining the leachate content and XRD spectra of the solid residues, it is deduced that the precipitation of Na (as Na 2 SO 4 ) and Si, probably as amorphous silica [23] (SiO 2 nH 2 O), results in a progressive reduction of the alkalinity during the subsequent re-circulation steps. In this way, alkalinity is reduced to 0.5 M NaOH by the 7th re-circulation step.…”

“…Since 50:50% coal/petcoke blend is gasified in Puertollano IGCC plant, fly ash is predictably enriched in V (up to >6000 mg/kg). Although the main proportion of V (>90%) is in the third valence state into the Al-Si fly ash matrix [17], it may be oxidised to V 4+ and V 5+ during NaOH leaching, then extracted as highly soluble vanadates in alkaline media [22][23]. This paper reports on the evaluation of the potential recovery of Ga and V from IGCC Puertollano fly ash using several NaOHbased extraction tests under different temperatures, NaOH concentrations, NaOH-solution/fly ash ratios (NaOH/FA) and extraction times (t).…”

Determinación del contenido de escorias en los cementos siderúrgicos

“…La determinación se realiza por transformación de los compuestos de manganeso (II) en Mn04~ utilizando como agente oxidante una disolución de persulfato amónico en medio nítrico y en presencia de Ag (I), procedente de una disolución de AgNOg, que actúa como catalizador (42). El permanganato formado se valora con una disolución patrón de arsenito sódico expresando el resultado en %, en peso, de MnO (elemento trazador o guía).…”