A discussion resource for process mineralogy using todays technologies
The steady increase in gold price over the last year or two has led to a renewed interest in the yellow metal and I thought it might be time to write a little about one of MinAssist’s favorite topics. I have spent many years now looking at all aspects of gold deportment programs and I wanted to share some brief concepts I find useful when implementing these types of programs.
Welcome back! I apologise for the long delay between posts. Things have been busy at MinAssist and the blossoming mining industry has kept demand for value added mineralogical analysis high and time for sharing our thoughts low.
Today I wanted to share some more thoughts on the usefulness of ore typing to mining and mineral processing operations. I have recently been working on a the beginnings of a geometallurgical program for an open pit operation where the whole processing chain from mining, through processing and to smelting is included. This has given me a unique opportunity to view ore typing from the perspective that although the mill is the direct customer of the mines ore types, consideration must be made for the effect that changing ore type can have on products fed to a smelter.
Welcome to another exciting year for the minerals industry. Compared to this time last year optimism is high and the drive to make the most of what appears to be a continuing boom in the mining industry is certainly there. At MinAssist we have seen increased confidence and optimism since the middle of last year and it seems that forward thinking mining companies are continuing to embrace mineralogy as a driver in many process optimisation and development projects.
The theoretical grade-recovery curve for an ore is a definition of the maximum expected recovery by flotation of a mineral or element at a given grade. This is defined by the surface area liberation of the value minerals and is consequently directly related to the grind size utilised in the process. The theoretical grade-recovery can be readily used to quickly identify potential recovery increases that can be gained through optimisation of flotation circuits and whether the process is running efficiently.
Ore characterisation is a very broad term that is viewed differently by geologists, mineralogists and metallurgists. It does however fundamentally cover the concept of defining the building blocks of an ore, giving insight into how best to deal with it.
The use of process mineralogy in comprehensive ore characterisation has always been a benchmark application. The depth of understanding that mineralogy can give us into the fundamental parameters of an ore can be invaluable in devising the most effective method for winning value from it. The advent of new mineralogical technologies, such as the e-beam based QEMSCAN and MLA, has made this even more accessible, opening up possibilities for comprehensive characterisation of ores at any stage in the mine life cycle.
Today I had a question about the need to use X-Ray Diffraction (XRD) for bulk mineralogy on a head sample destined for detailed QEMSCAN mineralogical analysis. This is an excellent question as it encompasses some fundamental aspects of how QEMSCAN works and the relative strengths of e-beam systems for mineralogy as opposed to more traditional methods.
An effective process auditing program is an important part of maintaining consistent recoveries in mineral processing operations. Traditionally, process audits are completed using chemical and metallurgical methods to monitor recovery and elemental distribution. The development of automated mineralogy and more efficient process mineralogy analysis techniques means that mineralogy is now more accessible as an efficient and comprehensive auditing tool.
A significant benefit of process mineralogy is the advantage it can bring in reduction of technical risk in mineral processing. Site metallurgists and managers can use mineralogy to gain an in-depth understanding of the ore being fed to their operation and reduce the effect of ore variability on recoveries.
Smart use of mineralogy in defining ore types and then monitoring their behavior through the process can help in numerous ways to improve the efficiency of control and key processes such as ore blending.
Tailings evaluation using mineralogy is an area that I believe can define the actual losses in a plant, while simultaneously providing the first step in defining why they occur. There is massive scope to use an understanding of tailings to see what is and what isn’t working in your process.
I wanted to start our exploration of process mineralogy in the middle of the mine life cycle, with its use in process optimisation and troubleshooting. Why start here you ask? Well process mineralogy can have the biggest impact and finds the most use in this area so it is a great introduction.
As a rule, from my experience the mineralogy of an ore is given lip service in process design and is generally considered the realm of the geologists. Key ore minerals are usually identified but a deep understanding of the minor ore minerals and gangue is rarely obtained through feasibility, piloting and design. Invariably, once commissioning is completed and the plant is operational the name plate recoveries are not achieved and a process of optimisation and general troubleshooting is undertaken. It is at this point that smart project metallurgists get hold of a process mineralogist to help them dig into the fundamentals of why recovery is low or grade targets are not being achieved.
When done to support these optimisation or troubleshooting projects process mineralogy can often quickly and efficiently identify the fundamental cause of problems, hence allowing metallurgical testwork to focus on identifying and validating potential solutions. When used early in the process, mineralogy can effectively focus the program and allow faster progression to results, minimising guesswork and ensuring that improved recoveries are achieved in the shortest possible time.
MinAssist actively promotes the use of process mineralogy in todays mining industry. To find out more about how MinAssist can work with you to develop simple systems to add value through mineralogy visit us at MinAssist.com.au
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