Technical Review and Evaluation of Ore Sorting Technologies on Precious Metals Operations

Brent Hilscher, Preetham Nayak, Leo Lorio, Nawoong Yoon

49th Annual Conference of Metallurgists, Vancouver, Canada, August 27-30, 2017.


Mining has been a staple to technological advancement ever since the dawn of time. By harnessing the different physical and chemical properties that each mining commodity brings to the table, more and more innovation is developed and manufactured. As these non-renewable resources continue to be extracted, the industry as a whole faces a challenge in finding the next economical deposit as well as declining grade at the current operations. By means of pre-concentration, ore sorting aims to separate the barren material from the valuable ore to reduce energy consumption and tailings generation, while increasing the feed grade, concentrate grade, mill recovery, and revenue. In addition, ore sorting allows the modification of deposit geometallurgy in order to allow the creation of an optimal mill feed.

This paper evaluates the applicability and challenges of ore sorting by utilizing the results from four different mines, and reviews them in detail. The mines include one underground and three open pit mines that are precious metal operations. In order to understand the applicability of ore sorting in these operations, initial rock-by-rock test results and different types of assays (atomic adsorption [AA], inductively coupled plasma [ICP], and fire assay) are utilized. Using the assay results, the grade recovery curves for ore sorting are generated and they are further improved by using and developing an ore sorting algorithm, which is discussed in this paper. The application and evaluation of ore sorting in greenfield and brownfield properties will also be discussed.

The state of the art ore sorting technologies for both rock-by-rock and bulk sorting are also reviewed in this paper. The future technologies on the horizon, including different combinations of sensors, are explained. The sorting technologies include X-ray transmission (XRT), X-ray fluorescence (XRF), colour, infrared, electromagnetic, and laser induced breakdown spectroscopy (LIBS).


CEEC acknowledges and thanks the Canadian Institute of Mining, Metallurgy and Petroleum (CIM), the Metallury and Materials Society (MetSoc) and organising committee for organising the COM 2017 Conference of Metallurgists hosting World Gold and Nickel-Cobalt.

Abstracts can be found at the CIM website (

Full papers published in the Conference Proceedings will be available on, and CEEC directs readers to to access and purchase published papers.