Increasing project value with ore sorting
Extracting valuable metals from the earth’s crust involves mining and processing a large amount of material. This typically involves putting a lot of energy into a huge amount of rock to liberate and extract the small amount of valuable metal contained within. Most base metal mines have approximately 99% waste (1% metal) and precious metal mines have approximately 99.99% waste (0.01% metal).
Ore sorting takes a different approach to traditional recovery methods. The ore is preconcentrated (i.e., separation of the economically valuable rock (ore) from the non-valuable rock (waste)), by rejecting the waste early in the process cycle before further processing. The benefits can be numerous including the following: reduced energy and water consumption (per tonne of produced metal); expansion of resource by cut-off grade reduction and potential increase in mine life; increase in total metal production; reduction in capital expenditure with smaller plant size and reduced footprint; and decreased tailings storage and associated risk.
Sorting provides an opportunity to improve the project NPV by increasing the amount of valuable metal processed with time. This approach brings cash forward, significantly increasing the viability of the operation.
Types of Ore Sorting
There are a range of technologies, sensors and applications available for ore sorting depending on the deposit and project economics. There are two main types of sorting - bulk and particle.
Bulk sorting is suitable for low grade and medium grade large tonnage operations. A sensor and diverter remove packets of low-value material from the run of mine (ROM) on a conveyor belt based on pre-determined grade. This method preconcentrates the ore at a very low operating cost by classifying small blocks of material (ranging from 1t to 10t) at 10’s - 1000's t/h throughput. Bulk sorting has proven to be successful at several base metal operations. In certain cases, bulk sorting has turned previously uneconomic greenfield projects or uneconomic satellite deposits, viable.
Particle sorting is suitable for low throughput operations with high value ore. A particle sorter scans individual 1-3” rocks and separates the rocks with a specially tailored algorithm at 10-100 t/h throughputs per machine. Particle sorting is a highly selective method of preconcentration that can reject the waste while achieving very high recoveries. This sorting method has seen applications at both base metal and precious metal mines.
Ore sorting at a copper-gold mine in Brazil
We recently performed a heterogeneity assessment at a large copper-gold mine in Brazil. Our assessment identified a way to sort and upgrade the marginal grade stockpile much earlier in the life of the mine, resulting in increasing the cashflow of the project. By adopting ore sorting, material previously categorized uneconomical was converted into economical ore which could be processed immediately. The feed grade of the mill increased and the NPV of the project was improved.
At another copper operation in Brazil, our familiarity with various sensing technologies and experience in bulk, as well as particle sorting, led us to use the client’s evaluation of particle sorting to identify a different approach. Our evaluation showed that the project saw the greatest benefit by combining both bulk and particle sorting technologies. The project is now progressing to the pilot scale of evaluation before implementation at production scale.
Ore sorting technology evaluation study adds value for client
A client in Australia engaged us to explore value-adding opportunities and technologies for a greenfield development of a copper mine and concentrator. By taking a holistic approach to the entire project’s economic evaluation, we were able to deliver a significantly better outcome. Our team’s strong understanding of ore sorting technologies and the rest of the process plant, enabled us to provide outcomes that improved the performance of the entire plant and the project. Our bulk sorting solution increased the revenue by over 10% and the project NPV by $400M AUD.
Let our ore sorting experts help you #FindABetterWay
With extensive project and technology evaluation experience, numerous studies, detailed engineering work, and the design and delivery of ore sorting projects in North and South America, we are here to help you find the right solution for your ore sorting project.
By looking at the whole operation and assessing the impact of different ore sorting technologies – from mining face to tailings management, we can unlock value. Working with brownfield operations, we’ve implemented strategies to reduce OPEX or increase metal production, while on greenfield projects, we’ve unlocked stronger project economics and lowered capital.
For more on ore sorting, and how we can help you with your project, contact Preetham Nayak.