Turning Rock into Metal

Turning Rock into Metal

Turning Rock into Metal: Stages of Metallurgical Development For Exploration Projects

hrl-newsletterThe development of a processing flowsheet for an exploration project is no small task. The process can take many years, and a certain amount of arduous meandering is inevitable as the project considers competing options.  For some projects this process can look more like flailing, as the project swings back and forth between process options, unsure of its bearings.
The key to making headway is careful and informed investment at the beginning of the project, ensuring later stages of investment are strategically targeted in a technically informed way.




Broadly speaking, the metallurgical development of a project occurs across three key stages:


The goal of metallurgical investigations in the early stages of a project is to provide early indications of a likely viable recovery process, along with possible operating costs.  The hope at this stage is to increase investor and technical confidence in the project, and lay a foundation for further development.

It is easy at this stage to do either too little testwork (a couple of tests should do!) or too much (let’s test everything!).  The key here is to start with testwork that has been carefully designed around the mineralogy and different geological domains of the resources. This can significantly reduce false starts for projects, which can lead to costly back tracking.


The outcome from the scoping study is likely to be a short list of possible process options.  This list needs to be shortened further, and a leading process option identified and optimised across the range of geological variability (domains) in the ore body.  It is this narrowing, optimising and variability testing work that typically occurs as part the Preliminary Feasibility Study.

Testwork in the PFS should remain disciplined and not be distracted by process options that may work in a laboratory but are too complex or narrowly defined to be viable in an actual operation.  The aim is not to come up with an optimised process, but an optimised process that can realistically be taken forward with the project.

In the PFS, more detailed information is obtained about the comparative trade-offs and costs associated with the flowsheet being considered.  Variability testwork enables a life of mine plan to begin to be developed, linking plant performance and product quality to the geological variability of the ore body.  In this stage of the project, it becomes more important for a strong process engineering group with a focus on practical outcomes to be designing and directing the testwork.


Metallurgical work in the Definitive Feasibility Study stage of a project’s development is dependent on the complexity of the ore body and the process being considered.  For simple ore bodies utilising very well established technologies, bench scale DFS testwork, similar to PFS testwork, can sometimes provide data of sufficient robustness to design a processing plant.

Complex ore bodies or unproven technologies will require the process to be tested in an integrated and continuous pilot programme.  The design and operation of these pilot programmes are both onerous and critical to the success of the project.

We strongly believe that testwork and piloting at the DFS stage should be coupled tightly with the process engineering for the project.  The metallurgical programme must be very tightly defined to drive out specific metallurgical parameters needed for process design, environmental approvals and permitting, as well as key information for the resource block model.  A flabby scope for metallurgical work in the DFS stage will not only be un-necessarily expensive, it will also fail to ultimately fulfil the technical due-diligence requirements for the project to be successfully implemented.

For more than three decades, Core has been assisting projects across all these stages of metallurgical development.  We help projects find economical and technically feasible options for their project, and help keep those projects moving.  The business is owned and managed by professionals with strong operational histories, with a focus on finding the solutions that work.