The speed of change in the mining industry today can mean potentially profitable efficiencies are being overlooked in the rush to meet production deadlines.
Because of pressures on staff to cope with day-to-day issues as production expands — and changing production needs – it can often happen that some technologies and equipment end up operating on duties different to those originally specified. This can result in some plants losing thousands of dollars per day, or per hour, simply by failing to ensure their processes and equipment are performing at optimum levels.
Outotec Pty Ltd (Australia) service products manager Michael Cook says process inefficiencies typically occurred where plants have experienced changes to their original design — be that in ore type, throughput or even duty.
“Typical warning signs of inefficiency occur when throughput volumes increase or when ore bodies changed dramatically,” Cook told Australian Mining.
“This puts additional loads on equipment that has been designed and configured for a specific duty based on original data. Equipment then doesn’t run efficiently because it’s out of its design criteria and the volume increased or change in feed composition is at a point where the equipment can’t cope.
“Plant operators then try to adjust and modify the existing equipment to suit the new duty, but there’s a limit to what can be done. Optimising plant efficiency requires moving to the next stage which often involves redesigning and reconfiguring or sometimes supplying a new system.”
Cook added that inefficiencies also occurred in operations with no formal or systematic optimisation program, at plants running antiquated equipment, and at operations whose experienced personnel had left, and new personnel are still untrained.
The key to enhancing performance, says Cook, begins with a site visit and an audit of the equipment. This should be carried out before inefficient equipment and processes increase the plant’s risk of breakdowns, but also before significant reductions in concentrate quality and recovery start to seriously affect the company’s bottom line.
“To enable an accurate and effective audit of your plant, our engineers work in collaboration with site personnel. The aim is to put ourselves in the shoes of the plant operators to understand their plant’s history and their company’s objectives. This is done during initial discussions with process and production personnel.”
During an initial site visit plant auditors observe equipment operation, review process trends, and record current equipment duty and performance.
If a full mechanical audit is required (in which all internals are inspected, drive monitoring systems and instruments are re-calibrated), then part of the audit needs to coincide with a plant shutdown.
“Basically, the initial site visit enables us to compare the differences in plant process performance based on the plant’s original specifications against changes that have since occurred,” Cook said.
“Using electronic design software, we look at what maximum capacity existing equipment can handle and the physical size will accommodate. If capacity falls within that range then we modify, adjust or retrofit to suit. If it falls out of that range then the equipment is never going to work and we look at completely different scenario and solution of removing and supplying a new piece of equipment.”
Once we identify the issues, bottlenecks or inefficiencies on site we can then determine the scope of supply and provide an accurate cost for an engineering study.
The engineering study commences using collated audit information as well as original specifications and test reports, as-built drawings and current equipment design and configuration.
After establishing differences in original specification and current duty, a new duty statement is compiled and used to determine changes that will result in more efficient equipment performance.
Deliverables in the engineering study may comprise of arrangement drawings, plant layout drawings, P & ID’s, geotechnical investigation and reports. It may also comprise definitive capital estimate for the proposed changes including design, supply, construction and commissioning. Relevant technical information such as technology data sheets, project management plans and construction program may also be included in the study.
“We also identify things like electrical and mechanical requirements and site access, HAZOP studies and safety requirements on site,” Cook said.
“Basically the initial site visit determines the picture while the engineering study grabs all those pieces of the jigsaw and puts it together.”
After determining the required modifications to the process and equipment, a process sample from the plant is obtained and lab-scaled dynamic testwork is carried out. Upon completion of the tests, the optimal equipment performance is determined and a comprehensive report is provided that includes all testwork data and any recommendations or modifications to the existing technology.
“The scope of this implementation can range from a simple modification or upgrade, to a full turnkey project including civil works, structural works, pumps, piping, electrical work and control systems.”
Cook’s key message to mine operators is not to assume that equipment is underperforming because it’s old and or hasn’t been properly maintained.
“The easiest way to identify a problem is to look at the big picture by comparing original performance against current performance and to go from there,” he said.
The best time to consider a process and performance audit, says Cook, is when anything has changed from the original design.
“Mine sites typically run ore bodies based on certain criteria. By the time the mine starts running that criteria’s often changed, albeit by a small percentage. In due time it will change in quantum leaps, depending on whether you’re trying to increase throughput, or it might just gradually shift. However, day-to-day incremental changes aren’t noticed,” Cook said.
“They just think things are slipping and things aren’t working as well as they did, but they don’t actually look back and identify the problem. They attribute it to operators and ore body changes and other things around the plant, but they don’t actually look at what has changed.
“The physical size of a piece of equipment and the configuration seldom changes, what does change is the operation techniques, technology, the orebody and the throughput. Operators should be conducting process audits annually, because annually it does change dramatically to a point where it’s going to affect overall performance and recovery.”
Service Products Manager
Outotec Pty Ltd (Australia)
08 9211 2226
0419 987 104
Outotec Australian Service Centre
02 9984 2500
Perth – 08 9211 2200