Ore sorting could be the panacea for nuggety conglomerate gold projects that are notoriously hard to develop after Novo Resources reported very positive gold recovery numbers from its Egina conglomerate gold project in the Pilbara. Novo is rapidly gaining credibility as a conglomerate specialist as it looks to add this new ore sorting technology to its suite of tools to effectively process its various styles of conglomerate mineralisation.
Canadian listed Novo Resources and engineering firm, Steinert, have been working together to develop some innovative new technology to recover very fine gold particles from its Egina conglomerate hosted ores at the TSX listed company’s Pilbara gold project. Steinert’s proprietary technology successfully extracted gold nuggets as small as 0.4mm from Novo’s dirt during the trials.
This new processing solution uses “induction sensors” to detect very fine gold and it is therefore a “dry and chemical-free” recovery method. An inductive sensor uses electromagnetic induction to detect or measure objects, including gold. Gold generates a magnetic field when current flows through it and the sensor senses it.
Novo successful trialled an ‘eddy current separator’ recently to recover gold nuggets ranging in size from 1mm to 10mm from waste rock.
This process is also “dry” and does not require any chemicals, providing a low capital cost solution utilising plant that is low maintenance, scalable and readily mobile.
Last year, the company excavated a bulk 150-tonne sample from the gold-bearing alluvial gravel horizon at Egina and this material was treated through Novo’s gravity gold plant. The simple technology uses gravity separation techniques to extract fine gold and coarse gold nuggets from the excavated materials.
Last year, the company trialled this gravity sorting technique with great success, recovering about 3.5 ounces of fine gold and small nuggets from the test, with portable XRF analyses indicating a purity of approximately 91-93% gold.
High tech x-ray transmission sorting of the conglomerates is also another option that has been tested by Novo. This process can split samples containing gold from the waste rock, based on gold’s characteristic high atomic mass and ease of electrical conductivity – the test resulted in 99.7% rejection of waste materials, which results in an extraordinarily high concentration of gold.
Gold at Novo’s Egina deposit is predominantly in the form of free nuggets, which generally exceed 1mm and the company is rapidly gaining credibility as an industry-leading conglomerate innovator as it looks to add this latest ore sorting mechanism to its suite of tools designed to process the various styles of mineralisation at its Pilbara gold project.
Rob Humphryson, CEO of Novo said: “Our recent tests on sortability of fine gold nuggets are very encouraging.
Novo is experimenting with a number of waterless, chemical-free processing techniques to handle the unique nuggety gold in our Pilbara conglomerates and lag gravels.
Tests over the past few months with Steinert mechanical sorters fitted with induction sensors have shown that we can now reliably identify gold particles orders of magnitude smaller than possible only a year ago.
… Whilst we have been assured that a detected gold particle can be reliably ejected, field testing of these technologies in 2020 will be the next critical step to prove this technology and gain an operational understanding of productivities, costs and detection size limits.”
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