JV Q&A: SRK’s independent lens on smarter ore processing

Key Concepts

Preconcentration (or Course Beneficiation): Separating valuable material from waste at an earlier stage of the mining process, before extensive grinding and processing.
Tailings: The waste material left over after the valuable minerals have been extracted from ore.
Ore Grade: The concentration of valuable minerals within the ore.
Metal Recovery: The percentage of valuable metal that is successfully extracted from the ore.
Sensor-Based Sorting: Using sensors (e.g., X-ray transmissive technology) to identify and separate particles based on their properties.
Discrete Event Simulation: A modeling technique used to represent and analyze systems where events occur at discrete points in time.

Preconcentration: A Paradigm Shift in Mineral Processing

Mining companies globally are facing increasing pressure to optimize resource utilization and minimize waste. This imperative drives the adoption of preconcentration, also known as course beneficiation. This approach focuses on separating valuable material from waste earlier in the processing chain, before the ore is subjected to energy-intensive grinding and extensive plant processing. The primary goals are to reduce the environmental impact associated with tailings, lower operational costs, and enhance investor returns.

The Traditional Mineral Processing Flowsheet and its Limitations

Traditionally, mineral processing begins with grinding the ore to a very fine size. This stage is a significant consumer of power and water. When valuable minerals are not recovered at this fine stage, they contribute to the large tailings ponds, which represent a substantial environmental burden and economic loss.

The industry's typical response to declining ore grades and increasingly challenging metal recoveries has been to increase the size of the processing plant to achieve economies of scale. However, this approach often fails to leverage the growing body of knowledge about ore bodies, which is increasingly informed by detailed measurements and data, potentially enhanced by AI.

The Core Principle of Preconcentration

Preconcentration aims to reject waste material before applying significant energy and water. By increasing the grade of the material that enters the main processing plant and reducing the overall volume of material processed, the size of the plant required to produce the same amount of metal can be significantly reduced. This is a critical tool for reversing the trend of processing lower-grade ores and facing more difficult metal recovery challenges.

Understanding Ore Variability and the Role of Data

The concept of "ore" itself is defined as material that can be processed economically. However, not all ore is created equal. It is often a mixture of high-value material and dilution or waste that has entered the process. Preconcentration allows for the segregation and isolation of these different value streams before they are processed. This approach leverages the increased density of data available today, enabling a more nuanced and sophisticated understanding of ore bodies and processing strategies, moving beyond a single, undifferentiated flow sheet.

The Importance of Independent Assessment

A crucial aspect of implementing preconcentration is the need for unbiased assessment, rather than relying solely on equipment vendors. SRK Consulting Group, as an independent consultancy, emphasizes its expertise in various disciplines, including preconcentration and bulk or particle sorting.

While equipment manufacturers possess valuable historical knowledge of what works, their expertise may be rooted in other industries (like recycling) and may not fully encompass the specific nuances of the mining industry. SRK's approach prioritizes understanding the economic opportunity and potential for value addition before engaging in material testing. This is critical because preconcentration does not always add value, and in many cases, it does not.

SRK's methodology involves:

Economic Evaluation: Assessing if there is a genuine opportunity to add value through preconcentration.
Targeted Testing: Once the potential benefits ("size the prize") are understood, clients can proceed with testing, guided by SRK's methods.
Informed Vendor Engagement: Clients can then approach equipment manufacturers with a clear context and understanding, allowing for more efficient application of vendor expertise.

Addressing Challenges in Ore Upgrading and Recovery

Miners face challenges in upgrading ore and improving recovery due to falling ore grades and increasing complexity. A key information gap has been understanding where the metal of interest occurs at a coarse particle size (e.g., 2 inches or 50 mm). Traditionally, to determine grade, material must be pulverized, destroying this valuable coarse-particle information.

Preconcentration efforts now focus on understanding how material presents itself immediately after crushing to the coarsest possible size. This includes identifying if metal is concentrated in fines, associated with softer material, or distributed differently.

Less Intrusive Sensor-Based Testing

Sensor-based testing, particularly using technologies like X-ray transmissive (XRT) technology, allows for non-destructive analysis of particles to determine the location of metals. SRK has developed a laboratory-based technology that can analyze relatively small samples to understand material hardness, breakage characteristics, metal distribution, and amenability to sensor sorting.

This approach is designed to be non-disruptive to standard metallurgical evaluations and overcomes the limitations of early-stage project samples (often only half drill core). Unlike traditional vendor testing, which might require 500 kg to 2 tons of material for a single large composite sample, SRK's method focuses on testing tens, if not dozens, of smaller mass samples. This allows for a comprehensive understanding of variability within the deposit.

Cost-Effectiveness of SRK's Approach

SRK has invested in its own sensor unit to conduct independent testing as cost-effectively as possible. They are also transparent with their protocols, aiming to reduce the cost per test, enabling clients to conduct extensive sampling and understand variability.

A novel outcome of SRK's testing procedure is the ability to simulate how a preconcentration circuit would perform. By adjusting circuit parameters and simulating different material flows, they can demonstrate the value addition of dynamic and variable circuit operation, going beyond static assumptions. This is achieved through discrete event simulation, utilizing SRK's team in Sudbury, led by Pierre Lereck. This dynamic simulation model is being tested to show how variable and dynamic circuit operation can add even more value than static assumptions.

This approach represents an exciting period for demonstrating the value of preconcentration to clients in a dynamic and variable manner.