Avalon Advanced Materials has moved a step closer to incorporating sensor-based ore sorting into its plans at the East Kemptville tin project in Nova Scotia, Canada, after the latest testwork came back with positive results.
As recently as July, the company said ore-sorting technology had the potential to upgrade the feed material to the processing plant, thereby reducing both capital and operating costs and the volume of tailings generated, and it has stuck by that assessment after the latest batch of work.
Sensor-based ore-sorting (an example from Outotec shown above) is an emerging technology seeing increasing application in the mining industry. It involves the scanning of individual rock particles on a conveyor using various types of available sensor technologies.
Depending on the chemical, mineralogical or physical characteristics, the particles of value are individually identified and separated from the ‘rejects’ by applying either a mechanical, hydraulic or, in the case of East Kemptville, pneumatic process.
The most recent work, which comes on the back of similar preliminary work in 2017, was conducted by Cronimet Mining Processing, which is providing technical and metallurgical services to Avalon.
Drill core samples from the in-ground resources at East Kemptville were delivered in July to a test facility in Kentucky, US, in order to determine the amenability of East Kemptville tin mineralisation for beneficiation using sorting technology.
Samples varying from relatively high-grade to low-grade tin concentrations were scanned using a multisensory sorter platform. Based on these scans, an algorithm was developed to allow for the separation of the material during tests.
The feedstock used during the test campaign contained 0.11% Sn, 0.06% Cu and 0.11% Zn. The first step of the testwork produced an upgraded product containing 0.47% Sn and a product mass yield of 12%.
Recovery versus grade data also showed ore sorting can be used to recover the zinc ore mineral sphalerite (which also contains indium) from this resource. The zinc-indium feed was successfully upgraded to 0.23% Zn in the first step, while copper content remained low.
Similar positive results were achieved in a preliminary ore sorting test programme conducted in 2017 using material from the low-grade stockpile, Avalon said. This confirms the technology can be successfully employed to upgrade both the in-ground tin resource as well as the stockpiled material.
Based on these results, Cronimet has recommend a detailed sampling campaign be conducted on the low-grade stockpile, followed by an extensive bulk testwork programme using a pilot-scale ore sorting plant to test the recovery of valuable minerals on a pilot scale.
Cronimet will be visiting the East Kemptville site in September to meet with Avalon and site representatives in order to design and schedule the sampling programme likely to involve the extraction of a bulk (circa-10 t) composite sample sometime in October.
The test programme, including writing of the technical report, is expected to take five to six months to complete. This will be combined with a confirmation drilling programme on the stockpile, which will be used to finalise the small-scale site re-development model to the feasibility level of confidence, following which it is contemplated Avalon and Cronimet would enter into a partnership for the joint development of the project.
In July, Cronimet started carrying out the installation of ore sorting equipment at Almonty Industries’ Panasqueira mine in Portugal. This particular installation was aimed at reclaiming coarse fraction tailings and would result in a production increase of about 10%, according to Almomty.