Case Studies

Drill-to-Mill plant optimisation projects help improve productivity and reduce total mining costs

During the past twenty years, some consultants and research centres have been involved in implementing a holistic methodology “Mine to Mill” to maximise the overall profitability of the operation rather than just optimising any individual process in a mining operation. These studies have shown that all the processes in the Mine to Mill value chain are inter-dependent and the results of the upstream mining processes have a significant impact on the efficiency of downstream milling processes such as crushing and grinding. Numerous Mine to Mill projects to date resulted in mill throughput increases of between 5 and 30 % depending on the ore strength and comminution properties.

In addition to the optimisation of existing mining and milling processes, this methodology has also been applied to greenfield studies and expansions. Our methodology requires intensive data collection – ore characterisation data, historical operating data, comprehensive drill&blast audits, surveys and benchmarking data. Site-specific mathematical models are developed for each process—blasting, crushing and grinding. By using these models, we can simulate a range of operating strategies for different types of ores in the mine and plant. EMC has worked in numerous Mine to Mill plant optimisation projects to date in which the mines achieved significant mill throughput increases. Please follow the below links for case studies.

We use the same methodology for our heap leaching projects, namely Blast-to-Leach. Barrick Veladero Gold and Eldorado Kisladag Gold are good examples of such projects focusing on productivity improvements, cost and recovery.

Ore characterisation data and blast domain definitions are used to develop mill throughput forecasting models. Life of Mine plan as well as long-term strategic mine planning are coupled to our Drill-to-Mill plant optimisation projects in order to maximize the profitability of the operation in the long term.

Drill-to-Mill Plant Optimization at Altynalmas Pustynnoye Gold MineEvaluating the Fragmentation Data from Copper and Gold MinesFragmentation Modelling and the Effects of ROM Fragmentation on Comminution CircuitsIntegration and Optimisation of Blasting and Comminution

Good final wall blast practices improve the safety of the mines and provide the opportunity of steepening the walls

The review of presplit and trim blasts and their results (crest loss/gain, toe gain/loss, half barrels, etc) as well as blast auditing offer to benchmark the operation. This process allows us to identify and recommend the opportunities to achieve improved results which should allow better slope stability, safety of the operation and may help explore the wall-steepening potential as a result of the improved wall-control practice.

Many different approaches exist to help achieve the desired end result of safe pit walls and compliance with pit slope design, suggesting that there is no single best-solution. EMC has developed skills in wall-control blast monitoring that can be tailored to site’s needs. With the application of advanced wall-control blasting practices and modelling, good results can be achieved while achieving significant opportunities for improved pit productivity and working efficiency.

We have worked at three major gold mines recently where we implemented novel measurement techniques, blast modelling and advanced wall-control practice. Crest loss and toe gains were minimised. Minor slope failures were prevented. All these operations commenced the opportunity of slope steepening after achieving good results with wall-control. They identified significant cost savings during the project.

Improving final wall and waste blasting results at Altynalmas Pustynnoye Gold mineImproving slope stability at Kışladağ Gold MineReducing Crest Loss at Barrick Cowal Gold Mine

Evaluation of the load/haul data provides some insights into the performance

We analyse the availability/utilisation of the mining equipments and their productivities. The analysis gives good insight into the shovel/loader performance and potential areas of improvement. Dispatch data is analysed in detail to understand the effects of blasting, rock properties, shovel type and operator influences on the instantaneous loading productivity. With improved blasting results, we help deliver increased dig rates, reduced maintenance and reduce the total mining cost. Analysis of blasting and load/haul data also provides insights to the optimisation of the waste blasts. Analysis of such data results in reduced total mining cost as well as helps understand the geology, shovel type and operator effects on the loading productivity. We have sufficient resources to conduct these analyses.

We have conducted a major study to optimise the waste mining cost at an Asian Gold Mine. This site was using one Hitachi EX1900, one Hitachi EX1200 and one CAT992. We have benchmarked the waste and wall-control blasts and improved the designs following our analyses. The study showed that

  • Blasts designs should be tailored to blast types (ore/waste/wall-control), rock strength/structure as well as loading equipment (shovel/loader).
  • Blast design templates were created based on above conditions. Initiation designs including delay timing were chosen for each condition.
  • Prior to the blast design changes, the mine was achieving 845tph and 638tph for EX1900 and EX1200 excavators, respectively. After the design changes, there was a significant change in dig rates (1100 tph for EX1900 and 798 tph for EX1200 excavators, respectively). It was shown that dig rates of the EX1900 and EX1200 excavators increased by 30.2% and 25.1, respectively.
  • The increases in dig rates resulted in significant cost savings to the Mine.
Monitoring and analysis of production waste blasts at the Cadia Hill Gold Mine

Vibration measurements and modelling are fundamental to control the vibration for Licence-to-Operate

We have proven methods of measuring blast vibrations at near-field and far-field as well as analysis tools to evaluate and control the blast vibrations considering the local regulations and site requirements. We have developed innovative blast designs by combining trim and production blasts to minimise the vibration and reduce the backbreaks in unfavourable rock mass conditions.

Case studies: Monitoring and modelling of blasting induced ground vibrationAn Alternative Approach to Determine the Holmberg–Persson Constants for Modelling Near Field Peak Particle Velocity Attenuation

Cast Blast Optimisation

We design cast blasts to deliver the required muckpile profile and the targeted cast percentage. Cost analyses are carried out to evaluate the value obtained by the alternative design options. Our approach has been used at several large open cast coal mines and resulted in increased cast percentage, improved muckpile profile and reduced total mining cost. We also carry out blast designs using dynamic buffering and some other methods for coal protection. Dynamic buffering helps reduce cost by removing need to buffer coal with trucks and dozers. Innovative blast designs utilising electronic blasting system help maximise coal recovery.

Muck Pile Shaping for Draglines and Dozers at Surface CoalminesImproving the Productivities of Surface Coal Mines in Australia

Explosive performance measurement and modelling

We have developed detonation codes to evaluate the realistic performances of the commercial explosives as a result of the industry sponsored research projects. We also have a large database of commercial explosives with their performances and bulk explosive product comparisons. These codes, databases and our experience help us provide independent explosive selection to the mining companies considering their needs.

A Non-Ideal Detonation Model for Evaluating the Performance of Explosives in Rock BlastingPrediction of the non-ideal detonation performance of commercial explosives using the DeNE and JWL++ codes

Managing ore loss and dilution using advanced blast designs

Having identified the ore and waste boundaries, one can use multiple initiation points to segregate ore and waste. Electronic blasting system is a great tool for such applications. Recent numerical simulations show improved ore/waste segregation when ore and waste move in different directions (see Preece et al, 2015).

We used segregation timing by adopting an advanced electronic initiation design. Below figure shows two initiation points which allow better segregation between ore and waste zones.

A recent work conducted at a gold mine identified the issue of throwing the ore into the pit void. Blast loading for the holes close to the free face was changed to minimise the powder factor around the pit edge. Blast timing was also changed to pull the material away from the pit edge. See the figures below. Ore loss was minimised using the alternative blast designs.