How a smart methodology improves mineral recovery

Louise Smyth

When a mineral processing operation encounters a reduction of performance where the efficiency of mineral recovery or the quality of concentrate falls below expectations, management usually resorts to a haphazard ‘tweak-test-tweak-test’ then repeat approach using baked-in corrections that might have worked in previous recovery operations. This type of shotgun approach to problem solving is not only time consuming and wasteful, but it also does not root out the specific mineralogical problem. Precisely identifying the mineralogical cause for process limitations enables operations to adjust the process with targeted solutions and enhance recovery without the trial-and-error approach. Nasaco’s Operational Mineralogy methodology does just that.

Techniques such as quantitative scanning electron microscopy, which is a tried and true technology for identifying the gangue minerals in flotation concentrates,  were previously only available to mineralogical researchers. Operational Mineralogy turns these advanced techniques into operational tools for completing in-situ mineralogical analysis.

After an operation detects a recovery problem, a Nasaco engineer samples process streams throughout the plant including feed, concentrate, trailing and waste streams. The engineer then completes a “bulk modal” analysis to identify which minerals are present in each stream. This preliminary investigation guides the engineer in creating an improvement plan. Next, using Nasaco’s proprietary software, an in-depth, second-stage analysis is completed as a starting point for dialling in solutions to improve the process at hand.

Of course, knowing the exact mineralogy of the ore does not improve recovery in and of itself. Operational Mineralogy makes enhanced recovery reality by improving the quality of concentrates. It addresses the mineral composition and mechanical structures with reagents and other chemicals prescribed for the exact ore in question. The secondary and more complicated analysis not only identifies minerals with precision, it also generates practical solutions for the efficient liberation of each mineral.

A whole-plant approach

Operational Mineralogy goes beyond compositional analysis. It also takes a whole-plant approach to implementing solutions. Engineers evaluate the current reagent and chemical schedules to determine how well the current process is working. The goal is to highlight areas where recovery is most successful and keep them. Engineers isolate the bottleneck points and focus on implementing solutions at pinch points where the current process has hit its limitations.

To eliminate the “trial and error” approach to recovery problems, Operational Mineralogy distinguishes itself with its ability to provide economical solutions for those pinch points. Using hard data, process improvements and alternative chemicals are proposed. Focused laboratory testing evaluates the recommended solutions for efficacy and more importantly, practical implementation.

Nasaco CEO Simon Isherwood explains, “Successful testing at this stage usually leads to a plant executing solutions that give a metallurgical result that is economical and can be realistically implemented.” Process solution testing is completed either at a customer’s site or at Nasaco’s South African laboratory, which boasts three Automated SEM units from the Field Electron and Ion Company to complete mineral liberation analysis.

In addition to precise mineralogy, engineers have expertise and experience in prescribing chemical and reagent formulation and blends. As a result, they can collaborate with an operation to design and provide custom formulations and blends of specific products tailored to a plant’s applications. Mineral processing plants benefit from the continuous support of through Operational Mineralogy services.

“The most obvious gains are in the metallurgical performance, improved recovery, improved quality of concentrate, and reduction of undesirable species, whether they are trace elements or gangue minerals,” Isherwood further clarifies.

However, the benefits are not just about improving concentrate composition. Improvements provided by Operational Mineralogy impact an entire mineral processing operation. Isherwood adds, “Changing or modifying a collector and frother suites often improves recovery, but is also reduces pH, uses a less hazardous product, reduces the amount of gangue floated and enhances the selectivity of the actual collector and frother suite by using a co-depressant.”

Recent Issues