Why we should consider operational mineralogy

In most operations we understand that minerals are being processed but we tend to almost exclusively rely on chemical assays to monitor the health of the process and make day-to-day decisions.  This often means that we are making decisions based on only one part of the puzzle and the ability to accurately identify issues and efficiently address them is compromised.  With lower grade and more complex resources becoming the norm it is becoming even more important to utilise all the tools available to maximise productivity and ensure that avoidable metal losses aren’t occurring.

Many operations recognise that to fully understand process behaviour mineralogical analysis is a useful or even necessary tool.  However, traditionally the only access to mineralogical analysis was through central technical centres or commercial laboratories, where turn around of results is at best measured in weeks and usually measured in months.  Often this means that by the time the results are generated mining has moved to a new area and little is gained from the exercise.

One solution to this is to bring the mineralogical analysis to the operation.   This concept, which we will refer to as Operational Mineralogy, is not new but has not received the kind of attention it should have in recent years due to difficulties in bringing suitable technology to site and more importantly retaining adequate expertise at operations to make the information useful.  A few attempts have been made to introduce automated mineralogy to operations, with examples such as Greens Creek and North Parkes, and more and more operations now send monthly composites for regular mineralogical analysis at central technical centres or commercial laboratories.  This is a great step forward but we still have a way to go before it is widely accepted that routine mineralogical information can make a difference to all operations.

We have been working on a number of Operational Mineralogy projects and over the next few articles will try to shed some light on what we have learned about where it can be useful and where more targeted mineralogical analysis is more applicable.

The approach

The approach that we have taken to Operational Mineralogy at MinAssist is to focus on generating mineralogical data that is useful for particular goals.  Essentially, what we want to know is when the process plant is underperforming, where that is occurring and whether the root cause can be attributed to an unexpected change in ore characteristics or an operational issue.

Where Operational Mineralogy can be incredibly useful is in increasing the efficiency of the Identify, Diagnose, Address cycle for continuous improvement.  This can be built using daily mineralogical analysis to identify potential issues and provide direction for diagnosis of the problem, which can then be used in more targeted projects for more detailed diagnosis and development of solutions.  Assessing mineralogical trends on daily composites can allow us to rapidly develop a process baseline, from which any fluctuations can flag that there may be an issue.

Day-to-day mineralogical monitoring data doesn’t need to be high resolution and can be easily generated for key streams in much shorter analysis times than would normally be used for detailed programs.  With a well setup program all of this can be achieved within 48 hours of the sample being taken, rather than waiting weeks or months for it to be sent away and analysed.

Of course, using lower resolution trend based mineralogical information is only useful if that data can be validated and it should be supported with more detailed analysis of monthly composites, along with regular audits of the whole process to ensure that systematic errors are not introduced.

Using this approach we have found that the use of mineralogical information can be normalised amongst the operational personnel, becoming a key tool in how they assess the operation.

Some benefits

The advantages of bringing mineralogy into the regular site monitoring program include:

• Fast response to changes in material behaviour fed to the operation.
• Embedment of an operational culture where mineralogy is used routinely to understand the fundamental cause of process issues.
• Elimination of the excuse that ‘the ore is the problem’ without any data to back up the claim.

Over time the mineralogical information for known ore types can be related to the resource model, allowing prediction of expected process behaviour at the mine planning stage.  The immediate change that we have noted on sites using operational mineralogy is that many of the assumptions that people make about process performance are very quickly confirmed or debunked.  This provides the operational personnel with a clarity of where to focus their efforts.   Even with only quite simple mineralogical data this rapidly changes how they look at the process and seek to address issues.

Some pitfalls

The benefits of operational mineralogy can be significant and rapidly achieved, however, without the right program structure there can be a risk that the information becomes overwhelming or is of such poor quality that it is of little use.  Some of the pitfalls that we have seen include:

• Insufficient attention to sample collection procedures can lead to poor quality samples and consequently poor quality data.
• Lack of expertise on-site can mean that the mineralogical data is considered too complex and isn’t used.
• Poor reporting structure and communication of results can mean that uptake of the outcomes with operational personnel is really poor.

These are all issues that can be addressed by setting the program up correctly and maintaining a strong focus on embedding the information in the culture of the operation.

One area that is more difficult to address is the difficulty in maintaining skilled personnel on site with the appropriate expertise to interpret mineralogical data.  This is especially true for remote operations and MinAssist has developed processes for remote support of operational mineralogy programs that addresses this issue well.

A better understanding

Overall, operational mineralogy, whether on a daily, weekly or monthly basis can provide sites with the missing tools for fully understanding process drivers.  It can be a relatively cheap solution when compared with the productivity benefits and we have yet to see an operation where the business case is not compelling.  While some care needs to be taken in the initial setup of a program there are enough examples out there now to show that it can be done and have great success.

If you have any questions feel free to contact us directly.  Also if you are interested in finding out more about process mineralogy make sure you download our digital book, which gives some more details on how to build mineralogical capability and start getting real value for your investment.