World of Metallurgy – ERZMETALL 62 (2009) No. 3 255 Levente Becze et al.: Characterization and Dissolution Behaviour of a Cl-containing Ag Material in Nitric Acid Solution 1 Introduction Chemical separation of metals by chlorination has been extensively studied [1-6]. Of particular interest here is the refining of gold from alloys containing silver and copper [7]. In the first stage of this process, chlorine gas is introduced to a reactor aimed at converting Ag to AgCl and Cu to CuCl, while gold remains in metallic state. As a further step, selec- tive leaching involving the use of hydrochloric acid (in the presence of air to convert cuprous to water soluble cupric) and subsequently ammonium hydroxide (to dissolve silver Characterization and Dissolution Behaviour of a Chloride-containing Silver Material in Nitric Acid Solution Levente Becze, Mario A. Gomez, George P. Demopoulos In this work an industrial chloride-containing silver mate- rial is characterized and its dissolution behaviour in nitric acid solutions is studied. For characterization of the silver- containing material, several techniques were employed in- cluding XRD, SEM-EDX, Raman, ATR-IR and solid state NMR. Based on the revealed phases, a diagnostic leaching method, consisting of ammonium hydroxide and nitric acid digestion steps followed by sedimentation, was developed that enabled to determine the quantity of the constituent phases: AgCl: 18 %, CuCl: 10 %, NaCl: 18 %, Fe x Ni y Zn z Mn v : 3.5 %, SiO 2 : 4 %, Ag: 37 %, Au: 3 %, Cu: 0.5 %, Fe: 1.5 %. In addition, the dissolution behaviour of this silver material was investigated in HNO 3 solutions, which led to the pro- duction of a chloride-free silver nitrate solution suitable for downstream precious metal recovery. An overview of this study is presented in this paper. Keywords: Silver recovery – Diagnostic leaching – Nitric acid diges- tion – Characterization – Hydrometallurgy Charakterisierung und Lösungsverhalten eines chloridhaltigen Silbermaterials in einer Salpetersäurelösung In dieser Arbeit wird industrielles chloridhaltiges Silber- material charakterisiert und sein Lösungsverhalten in Sal- petersäurelösungen untersucht. Zur Charakterisierung des silberhaltigen Materials hat man sich unterschiedlicher Verfahren bedient, u.a. XRD, SEM-EDX, Raman, ATR-IR und Festkörper-NMR. Auf der Grundlage der entstehe- nden Phasen wurde eine diagnostische Laugungsmethode entwickelt, die aus Aufschließungsstufen mittels Ammoni- umhydroxid und Salpetersäure mit anschließender Sedi- mentation besteht. Dies ermöglichte die Quantifizierung der Mengen der anteiligen Phasen: AgCl: 18 %, CuCl: 10 %, NaCl: 18 %, Fe x Ni y Zn z Mn v : 3,5 %, SiO 2 : 4 %, Ag: 37 %, Au: 3 %, Cu: 0,5 %, Fe: 1,5 %. Weiterhin wurde das Lösungsverhalten dieses Silbermaterials in HNO 3 - Lösungen untersucht, was zum Erhalt einer chloridfreien Nitratlösung führte, die sich für eine spätere Rückgewin- nung der Edelmetalle eignet. Diese Arbeit bietet einen Überblick über diese Untersuchungen. Schlagwörter: Silberrückgewinnung – Diagnostische Laugung – Sal- petersäureaufschluss – Charakterisierung – Hydrometal- lurgie Caractérisation et comportement de dissolution d’une matière d’argent chloruré dans une solution d’acide nitrique Caracterización y comportamiento de disolución de materiales argénteos que contienen cloruros en soluciones ácido nítrico Paper to be presented on the occasion of the European Metallurgical Conference EMC 2009, June 28 to July 1, 2009 in Innsbruck, Austria. chloride) is applied to recover metallic gold in high purity (>99.9 %) [7]. By this extractive metallurgical process, the recovery of pure gold from alloys such as doré, jewellery or electronic scrap can also be accomplished [7]. During chlorination considerable amounts of precious metals report to slag. One such slag consisting predomi- nantly of 30 % Ag (as AgCl), 20 % Cu (as CuCl), 1 % to 5 % Au and 1 % to 5 % Ag was subjected to a mini-pilot scale operation with the purpose of converting silver chlo- ride to metallic silver. This process consisted of dissolu-