mechanical sorting Archives - International Mining

Novo Resources Corp has advised that Phase 2 mechanical sorter trials using a Steinert KSS 100F LIXT fine mechanical sorting unit have commenced at the Nullagine gold project, in Western Australia.

Over recent weeks, the sorter infrastructure has been mobilised, constructed and commissioned adjacent to the company’s Golden Eagle processing plant at Nullagine. Fifty samples from the company’s Comet Well, Purdy’s Reward, Egina, and Talga Talga projects ranging in size from 800 kg to around 5 t have been delivered to the site for crushing and screening ahead of Phase 2 sorter test work.

The test work program in late 2021 and early 2022 is designed to achieve multiple objectives:

Construct and commission the sorter and associated infrastructure (Phase 1 – complete);
Tune the sorter to the various geological regimes and size fractions and train Novo operators in its use;
Process samples from multiple Novo projects around the Pilbara to field test mass pull to concentrate;
Establish assay protocols for sorter concentrate ‘accepts’ and waste ‘rejects’. Smaller concentrate mass will be processed by Chrysos PhotonAssay technology at Intertek’s laboratory in Perth, Western Australia. The Acacia reactor and electrowinning apparatus in the gold room at the Nullagine is being commissioned to accept larger masses of material from accepts and reject samples. This will be particularly important as the test work program moves to Phase 3 at the company’s Comet Well project in 2022 to test bulk samples (up to 20,000 t of potentially mineralised material from the Comet Well and Purdy’s Reward projects).

The sorter infrastructure, designed and constructed by OPS Screening and Crushing Equipment, is a fully modular and containerised turnkey plant deployable to any of Novo’s tenements in the future for test work and potential large bulk sampling and processing, the company said. The sorter includes feed and product transfer conveyors, allowing the sorter to produce gold-bearing concentrates in a single pass for further upgrading or downstream processing.

“This Phase 2 trial of the sorter within the Golden Eagle processing facility area is the culmination of several years of test work conducted by Novo to determine the amenability of mechanical sorting to its 13,250 sq.km of tenements across Western Australia,” the company said. “Mechanical sensor-based sorting utilises X-ray technology, 3D colour laser and metal induction to identify gold-bearing material. A high-pressure air jet ‘shoots’ these gold bearing particles into a collection system to produce a concentrate for further downstream processing.”

Next steps at the project include:

Phase 2 completion prior to May 2022 – complete processing and assaying of all outstanding coarse, mid and fines samples from the company’s Comet Well, Purdy’s Reward, Egina and Talga Talga projects and establish operating protocols for processing larger mass; and
Phase 3 commencing May 2022 (subject to approval from the Western Australian Department of Water and Environmental Regulation) – relocate the sorter and infrastructure to the Comet Well project for bulk test work.

Rob Humphryson, CEO and a Director of Novo, said: “Novo is delighted to see the sorter in operation at the Nullagine gold project. This represents the culmination of considerable planning involving a dedicated consortium of mechanical, electrical, geological and processing experts aiming to maximise the likelihood of success of an innovative application for sorting in the gold industry.

“Results from Phase 3 bulk sampling program set to commence in 2022 at the Comet Well and Purdy’s Reward projects, together with the results of the Phase 2 trials at the Nullagine gold project this year, are expected to provide sufficient geological and operating certainty to enable Novo to progress towards commercial operations at Novo’s nuggety gold deposits.”

Novo Resources says it has completed encouraging processing trials on gravels extracted from its joint venture Egina gold project, in the Pilbara of Western Australia, at Steinert’s testing facility in Cologne, Germany.

Phase one of the company’s joint venture with Sumitomo Corp at the Egina gold project centres around gaining a better understanding of geology (grade, continuity, controls, gold particle size distribution, gold location within gravels, gold genesis, etc.) but also involves high level desktop studies and trials to develop potential future processing and mining methodologies.

Preliminary tests of eddy current separator (ECS) technology indicate promising potential to directly extract gold nuggets from gravel, the company said. This is one of several dry processing methodologies being considered by Novo for gold recovery at the project.

Tests conducted on a spectrum of nugget sizes ranging from 1-10 mm demonstrated consistently high gold nugget recovery via ECS technology. Nuggets that underwent testing were recently extracted from gravels at Egina, the company said.

ECSs are predominantly used to recover select metals in the scrap metal industry. Material is fed onto a conveyor, the head pulley of which contains an adjustable high-powered magnet spinning at very high rotation rates, 4,000 rpm in Novo’s tests, independent of the speed of the conveyor, Novo said. This spinning magnet induces an alternating magnetic field that differentially repels non-magnetic metals such as gold.

This magnetic repulsion causes gold nuggets to lift, or fling, off the end of the conveyor belt where they can be separated from waste material by a steel plate. These trials were designed to establish whether Egina gold nuggets react sufficiently to reliably be separated from waste material.

Novo said: “Gold at Egina predominantly occurs as free nuggets of which most are above 1 mm in size. This presents opportunity to explore innovative technologies, some used commercially in other applications such as ECS technology, to assess their efficacy for use at the Egina gold project.”

In addition to ECS technology, Novo conducted initial testing of Steinert mechanical sorting technology to detect small gold nuggets utilising an Argos EM electro-magnetic sensor, it said. Fine gold nuggets, around 1 mm, were consistently and readily detected indicating potential for direct mechanical sorting of gold nuggets, Novo said.

As a result, a combination of mechanical sorting and ECS technology is also being considered as a potentially viable means of dry processing at Egina, the company said.

Rob Humphryson, CEO and Director of Novo, said: “We are very encouraged by these initial laboratory test results utilising ECS technology. Our mantra when testing new technology and its application to our projects is to ‘test quickly and test cheaply’, and we now have in hand sufficient encouragement from these tests to consider ECS technology highly prospective for application in the field.”

The company said this preliminary testing shows ECS technology can play an important role at Egina, with potential application as a processing solution or an exploration tool, or both. “This technology generates significant inherent advantages: it requires no water, no chemicals, is of low capital cost and is readily mobile. It can also be employed along with other technologies and is scalable,” the company said.

Novo thinks field tests are warranted at larger scale to better understand recovery efficiencies, operating costs and throughput rates and the Company plans further work with Steinert to study schemes in which ECS machines, or ECS machines in combination with mechanical sorting technology, can achieve efficient recovery of gold nuggets at Egina.

The company concluded: “As Novo learns more about gold size particle and mass distribution of gold in Egina gravels, the company can then begin to estimate gold recovery.”

Steinert mechanical ore sorter starts up at Novo’s Nullagine gold project

Novo looks to scrap metal industry for Egina gold nugget separation options