The ore size-reduction process is an integral part of each of the sub-processes from excavation of ore to the final finished particle size and includes: blasting, crushing, screening, grinding and separation.
Grinding prepares minerals for direct use, transport or further processing. In many cases, grinding is used to liberate valuable minerals from waste material.
The opportunity is to optimise the production chain to minimise the overall energy consumption but with consideration of product losses that can occur if waste is rejected earlier in the process.
The blasting design affects the energy required in crushing. The size achieved in crushing impacts the amount of material that cannot pass through screening and must be re-crushed. The size of material passing through the screen impacts on the energy use of milling. The amount of material rejected as waste between stages affects the energy use of the system and the potential amount of product lost in the waste stream.
Sectors and common applications
- Mining − comminution of various ores
- Estimated energy savings in 2014 was 18 PJ.
|1. Energy saving potential|
|1.1 Level of energy efficiency||12/15|
|1.2 Market prospect||2/10|
|1.3 Energy saving potential||5/10|
|2. Technical practicality|
|2.1 Innovative or advanced nature||15/25|
|3. Economic characteristics|
|3.1 Investment per unit energy||6/10|
|3.2 Payback period||10/10|
|3.3 % of Industry $ gross added value||5/5|
|4. Social characteristics||3/5|
BHP Billiton Ltd made energy efficiency gains through grinding optimisation in their SAG throughput for milling at their Nickel West mine. Analysis of the energy efficiency of SAG milling indicated that one module had consistently outperformed another. Investigations noted the design improvements to the pulp lifter and discharge grate, which were subsequently implemented on the other module. This resulted in an increased throughput and a reduction in energy consumption per tonne, corresponding to an annual energy saving of 59.6 TJ.
Other companies which have identified grinding optimisation as a source of energy savings can be found in the EEO Opportunities Register on EEX, including:
For more information, see:
Improving-Energy-Efficiency-in-Barrick-Grinding-Circuits (PDF, opens in new window)