The following article appeared in the July 2013 issue of Mining, People and the Environment. Thanks to author Graham White, and Ruth Green at Aspermont for a great feature.
Classic economic theory tells us that competition and the profit motive should herd every enterprise along the road to best practice.
If that is the case, there is a glitch in the mechanism when it comes to energy-efficient comminution, because the gulf between best practice and rank-and-file operators is considerable.
Studies by the Coalition for Eco-efficient Comminution (CEEC) suggest that the minerals industry could cut energy use in this area by 15-30% if current best practice were adopted industry-wide. Energy savings of up to 50% are achievable within a decade from introducing already-identified advances.
Improvements of this scale would both provide operational savings and make it possible to treat lower-grade or more complex ores in an economically viable way. They can also help companies meet requirements for lower carbon emissions, many of which can be implemented at modest cost.
So why are these relatively easy pickings not being taken up? That was one of the questions posed at a CEEC workshop at Noosa in Queensland, Australia, in 2012 that was run in collaboration with JK Tech Pty Ltd.
The prime purpose of the workshop was to develop a road map leading to substantial energy reductions per tonne of metal produced. The panel consisted of 37 experts representing mining companies, providers of mineral processing equipment, engineering companies, researchers and consultants.
Collectively, this team offered insights into current operating practice, available and emerging technologies and potential new developments. Separate teams were dedicated to short- and longer-term strategies.
Discussion in both groups quickly revealed that the challenges were not only technological: cultural and structural barriers to the adoption of available and emerging technologies were an equally significant factor.
The structural separation of different parts of the mining-comminution process within most companies and the lack of agreed measurement metrics makes it difficult for organisations to understand their level of energy efficiency.
Many have little idea of how far short of best practice they fall, since there is no recognised industry yardstick.
This, combined with a range of other factors, means that the issue generally has a low corporate priority, notwithstanding the potential for swift efficiency improvements and the benefits that follow.
The good news for the industry – and for individual companies – is that the road map teams found that none of these impediments is formidable: most can be readily and economically addressed.
One of the first points established by the road map teams was that energy efficiency cannot be measured only at the mill.
Blasting, sorting, blending and ore characterisation all have significant roles: indeed, as the workshop progressed, the potential to improve energy efficiency by better integration along this chain became increasingly apparent.
It was also acknowledged that a true measure of energy use includes not only energy directly consumed in size reduction, but also in the manufacture of comminution consumables such as steel grinding media and liners. While the need to include these was noted, the biggest focus was on direct operational savings.
The overall goal was to create a road map that: identifies the benefits of improved efficiency; defines the obstacles; and provides direction on how the industry broadly and companies specifically can improve performance.
Sub-elements of this included:
- identification or creation of tools and benchmarks to evaluate performance;
- promoting adoption of best practice and best technologies;
- identifying the key business drivers for improved energy efficiency and the managerial key performance indicators (KPIs) associated with these; and
- identifying communications strategies and tools to motivate companies to pursue these goals.
Most operations already have the capacity to make relatively swift and significant improvements. While technology is advancing on a range of fronts, there is no single technology evident at this stage that will deliver step-change improvement.
The big gains will come from the cumulative impact of integrating a range of available or identified advances. Cultural and organisational changes will bring the biggest benefit.
Given that the workshop group, which comprised industry professionals, equipment suppliers and engineers, was able to easily identify known but under-utilised opportunities for improving efficiency, the focus turned to the operational environment. What are the impediments to their speedier adoption? Why do they not have a higher internal priority?
One observation was that energy-efficiency strategies sometimes lack support from higher management. This may in turn be influenced by factors such as the absence of agreed measures of efficiency and of industry benchmarks.
There is no efficiency rating against which a plant can be easily measured. It is not considered a key performance indicator (KPI) for the relevant executives. In the absence of such measures, energy efficiency can be overshadowed by the focus on capacity and throughput and obscured by the higher energy demands required by lower-grade ores and complex mineralogy.
The massive investment required by mines and processing operations also makes companies risk-averse to any departure from established operational technologies and procedures.
Workshop members also raised the question of whether the net present value (NPV) formula used to evaluate competing options resulted in undue weighting of capital expenditure (capex) over operational expenditure (opex), given that the latter is often discounted over long periods. Given the enormous costs of new projects, the emphasis is often on minimising capex.
Blockages in information flows
There are two areas where inhibitions on information exchange hinder efficiency improvement.
Firstly, within companies there is commonly a lack of a unified approach. Work divisions can create a silo mentality and the lack of standardised metrics means that inadequate attention is given to how changes at one point in the materials flow (blasting, separation, characterisation) might affect energy use at subsequent stages. This may be exacerbated by a shortage of skilled and experienced people. There also appears to be a lack of understanding of the ease of implementing many changes, even where the effectiveness of these changes has been clearly established elsewhere.
Secondly, between companies there is inadequate sharing of information, often related to the perceived protection of intellectual property, or as some members described it, “IP hoarding”. More open exchange might create better benchmarks and do a great deal to improve the industry’s environmental impact and its resultant public image.
Both within companies and across the industry, a more holistic approach is needed.
1. Develop an energy rating system that can be used across all operations
Clear benchmarks and standards for use by process designers, equipment manufacturers and project operators need to be developed. This will allow site performance to be compared with industry standards and with other plants operating in similar circumstances. Operators could then measure themselves against best practice.
A key extension of this is the development of a four-star energy rating system, similar to that used on appliances. This can be used to audit:
- overall operational efficiency;
- planning systems;
- equipment efficiency;
- maintenance systems;
- control systems; and
- technical support systems
2. Adopt best -practice technology
As noted above, there is a substantial gap between the operational standards of the majority and industry best-practice.
These gaps occur across the chain, from the mine through subsequent processes, including ore sorting, classification or pre-concentration, reprocessing and product recovery.
An integrated approach across this value chain would produce very substantial improvements. The key recommendations that stand out from a rather more extensive list include measures to move size reduction upstream – as far as possible – from the more expensive final grinding stages. Possible actions include:
- intelligent blasting to optimise plant-feed size distribution;
- in-pit sorting and conveying to replace in-pit crushing;
- better blending/stockpile management;
- early waste-rejection strategies such as coarse flotation and coarse gravity separation; and
- low-grade pebble rejection from semi-autogenous grinding (SAG) product and pre-concentration by screening, ore-sorting or dense-medium separation (DMS).
There are also a number of other recommendations relating to optimising efficiency of equipment.
3. Identify and implement appropriate business drivers and KPIs
As noted above, many barriers to progress relate to business practices, rather than technology. Industry needs to work collaboratively to develop, implement and review appropriate energy metrics.
These metrics must be universal, well understood and auditable. It is also essential to put meaningful business drivers in place if improvements in energy efficiency are to be achieved. The process could be modelled on existing standards such as health-and-safety regulations.
4. Communicate the benefits, motivate, engage and train
A key recommendation of the workshop was the need to raise awareness and build support for improved energy efficiency within the industry. It is important to communicate the benefits of energy-efficient comminution to all stake-holders. This includes building an understanding of the potential for change and the skills required to implement it. It will also require the breaking down of disciplinary silos within companies and across the industry.
Grasp the opportunities
This need for motivation – built around an understanding of the benefits of greater energy efficiency and an awareness of the costs of failing to do so – emerged as one of the principal goals of the workshop group.
There was a widespread view that there is low awareness of the ease with which many of the recommended changes can be implemented, and a risk-averse mentality to change.
A tentative approach to new technology is in many ways understandable: orebodies are complex and in the face of this operators are cautious about adding a new variable in unfamiliar technology or process. In general, it can be said that operators are comfortable using existing technology.
This is unlikely to change as long as there are no simple, widely accepted metrics to tell them in undeniable terms that their performance falls short of benchmarks. Until there are such benchmarks, energy efficiency in comminution will not feature in executives’ KPIs. Faced with declining grades, the key focus is more often on expanding throughput than increasing energy efficiency.
Increased energy costs may create an added impetus to efficiency in the future, but for the moment other cost pressures tend to override it as an issue. This is regrettable because it slows the development of the practices and processes that may be required in the future while social and political pressures for energy reduction continue to mount.
Increased awareness and motivation may also be necessary to encourage greater co-operation within the industry, particularly in relation to intellectual property. There is a case for making information more widely available in the interests of improving the industry’s image.
Developing cross-team engagement and cross-disciplinary reviews within a company or operation was widely seen as a key step. It was acknowledged, however, that some of the impediments to better communication flows – particularly within companies – stem from the fly-in fly-out (FIFO) culture that inhibits the communication required for long-term optimisation.
These add challenges to the potential for cross-team engagement and cross-disciplinary reviews that were identified by the workshop as a key step to improvement. One proposed solution is the greater use of dedicated off-site experts that are able to access mine and plant data remotely. These could compensate for any shortage of on-site expertise.
Research and development
While much of the above relates to efficiency improvements that can be achieved within technologies that are currently available, the workshop groups identified a wide range of research priorities that could, should and, in some cases, are already being pursued.
Many of these priorities related to improved data communications and management systems to facilitate automatic adjustment of the ore-treatment and ore flows to maximise efficiency.
Others related to the development of improved equipment such as new-generation crushers, variations on high-pressure grinding rolls (HPGR), variations on IsaMill and the development of the grinding roller mill. Others looked to liberation by electric pulse fragmentation, microwave or ultrasound.
Like all good road maps, the one developed by the CEEC/JK Tech workshop groups has a ‘Start Here’ point that corresponds with where the industry is now. While it explores potential new technologies and approaches to energy reduction, it also acknowledges the cultural and operational environment in which current decisions are made – and offers practical directions on how to proceed from there.
Energy efficiency is already an important factor in mineral processing, with comminution being the biggest energy consumer. Improvements in this area will be key not just to operational efficiency but to community acceptance.
This workshop has pointed out just how accessible such improvements can be. As one well-known sports-goods company says: Just do it.
Graham White is a freelance writer with a long association with the minerals industry. For more information on the CEEC and the road map, visit www.ceecthefuture.org.