Characterization of Gold Ores – The Basis of Gold Traceability

by Barbara Beck (presenting author)1, Stefan Ansermet2, Jonathan Jodry3, Massimo Chiaradia4, Suren Erkman1


1: University of Lausanne, Switzerland; 2: Geological Museum of Lausanne, Switzerland; 3: Metalor Technologies SA, Switzerland; 4: University of Geneva, Switzerland

 

The global gold value chain is attracting scrutiny, in relation to environmental, social, and geopolitical issues. Switzerland plays a central role in this value chain, being the main hub for trade and refining: 60-70% of the primary gold extracted worldwide is shipped to Switzerland to be refined and re-exported. The supply chain of primary gold suffers from a poor reputation: the situation in artisanal mines is often criticized, both humanly and environmentally; and even the supply of gold from large mines is not always free from doubt. Despite the intervention of Swiss Human Rights NGOs, the Federal Council decided in 2018 not to take any legal action, leaving responsibility to companies.

Our project it is a joint initiative between Metalor (Switzerland), the worldwide most important refiner of gold, and Universities of Lausanne and Geneva, with support from Innosuisse.

We address a crucial aspect of the gold value chain: the traceability of primary gold. By developing a scientific methodology – a kind of analytical fingerprint (AFP) based on isotopic and chemical characteristics, we attempt to determine the origin of gold with a high degree of reliability.

Our preliminary study focus on the first metallurgical processes – from ore to doré (unrefined gold ingot). On behalf of the AFP, we aim at answering the following questions: Is it possible to distinguish between different types of ore deposits? What are the influences of metallurgical processes on the AFP? Is there a «memory» of the metallurgical processes, thus making it possible to distinguish gold extracted by gravimetric enrichment from gold extracted by amalgamation?

Our research is based on the study of three mining sites in Peru: La Rinconada in the Andean Cordillera (primary deposit, amalgamation enrichment), Ananea in the Altiplano and Hueypethue in the Amazonian Basin (both secondary deposits with gravimetric and amalgamation enrichment).