Gold ores are frequently amenable to some degree of particle sorting when sulphide or quartz is associated with the gold. As regards the complex combination of sulphide associated with gold, the pre-concentration of the ore in the early stages of the production process via sensor-based ore sorting is best achieved by X-ray-transmission (XRT).
XRT sorting technology is based on a planar projection of data derived from the X-ray attenuation of a flowing particle stream. Where metals are present in ores, the elements with higher atomic numbers will be identified, but gold itself will not be recognized by the XRT sensor because it occurs in such low concentrations. However, the metals which occur in higher concentrations, such as Fe and Cu, can be present as sulphide mineral phases. And if these sulphide mineral phases are associated with gold, and are also found in sufficient size and concentration, they can be recovered with TOMRA´s XRT sorting technology.
EVEN BETTER RESULTS WITH TWO-STAGE SENSOR-BASED ORE SORTING
Particle sorting of gold ores, using XRT and/or laser sensing, is generally an effective method. For instance, a two-stage sorting flow-sheet utilizing an XRT rougher and a laser scavenger (or this same combination in reverse) has already delivered an optimized recovery for a range of deposits. It should be noted that, even for quartz-type gold deposits, the gold is typically associated with pyrites inside the quartz vein and in a ‘halo effect’ around the edge, as well as in the quartz itself – though mostly in smaller concentrations. Two-step particle sorting flow-sheets using these types of configuration have regularly accomplished ore recoveries of more than 90% and mass removal of between 30 – 60%.
Because of the complex nature of gold ores, it is essential to fully investigate and understand their sorting feasibility in order to make informed decisions and manage any potential risks. Thus application knowledge and experience will always play a critical role in the development of an optimally functioning process. If you want to increase your productivity, contact us today to find out how TOMRA’s ore sorting technology can add significant value to your gold operation.