Ways to save

Embed energy efficiency into corporate and site management practices

Achieving progress on energy efficiency is underpinned by corporate support and the formation of an energy management team to enable the design and implementation of a whole of mine energy management system. An energy management system provides a framework within which to undertake effective energy use measurement, analysis, as well as identification and implementation of energy efficiency opportunities.

Some examples of opportunities in this area are outlined below.

Use an energy-mass-balance assessment approach

Developing an energy-mass-balance (EMB) to model energy use provides a starting point to underpin an effective energy management system. An EMB assists understanding of the energy flows, mass flows, and other factors influencing energy use, to determine the efficiencies of processes and equipment. Thorough EMBs can reveal significant energy and cost savings by identifying:

  • how much energy is being used, wasted or lost through, for instance, fixed’ energy overheads (vehicle idle, ventilation, conveyors left on etc) and start-up/shut-down losses (eg truck cool-down)
  • whether systems and equipment are operating according to design and work schedules 
  • energy use variability and its underlying causes 
  • if useable waste heat is being produced—or processes could be powered by other energy sources.

An EMB requires a company to look at their mining site as a whole system. In the process, an EMB can help to identify ways of producing products or services with substantially lower energy and resource inputs.

For more information

Energy Mass Balance: Mining 2010

(PDF 2.2MB)

Department of the Environment and Energy

This guidance document outlines the key considerations and potential approaches for the development of an energy-mass balance for a mining operation.

Upgrade the ore concentration

Achieving optimal energy efficiency levels for mining operations requires accurate and timely information on the nature of the ore bodies and the rock feed provided for mineral extraction and comminution. Investing in understanding and characterising mineral ore bodies enables the highest concentration ore bodies to be targeted for blasting and extraction.

Selective blast design, combined with ore sorting and gangue rejection, significantly improves the grade of ore being fed to the crusher and grinding mill leading to large reductions energy usage compared to business-as-usual.

Some examples of opportunities in this area are outlined below.

Undertake resource characterisation

The level of ore concentration variability and other characteristics of rock types significantly influence ‘mine to mill’ design and operational efforts to minimise total energy usage. Typically, geologists’ predictions about the ore body and mineral processing performance from observations at the core scale are different to the reality faced by engineers.

Geometallurgy helps to address this difference by first performing many smaller volume (lower-cost) tests; then using the data obtained to construct a 3D geometallurgical model of the ore body. The 3D geometallurgical model is used to inform a smart blasting approach that targets the sections of the ore body with the highest ore grade concentration. Leading companies, which have partnered with the CRC ORE have shown that this process can reduce business as usual trends in energy use per tonne by 10–50% of metal.

3D geometallurgical models of the ore body can also enable the optimal design of mine to mill circuits and the integration of energy efficiency into the measurement and accounting of energy use per unit of metal produced. For example, the Sustainable Minerals Institute (SMI) at the University of Queensland, in partnership with Anglo Platinum, has developed the ‘Geology-Mine-Plant Management Tool’ to optimise the energy use, water use, and greenhouse gas emissions across the whole geology-mine-plant extraction process.

Implement selective smart blasting, ore sorting and waste removal

Selective smart blasting, ore-sorting and waste removal can be used to increase ore grade  ahead of crushing or grinding by removing coarse waste material (gangue). The CRC ORE at the University of Queensland has shown that it is possible to achieve as much as a 2.5 fold increase in average mineral ore concentration feed to the grinding mill through using smart blasting, ore sorting and gangue rejection.

Selective smart blasting

Conventional blasting blasts the entire block/region of a mine to achieve the top size that can be transported in haul trucks and processed through the primary crusher. Selective/smart blast design technology uses geometallurgical data to target relatively high ore concentration sections of the ore body with greater blast energy. This significantly improves the grade of ore being fed to the crusher and grinding mill. The net total energy consumed at the crushing and grinding stages is reduced as:

  • a reduction in the feed size to the primary crusher requires less energy to crush the ore to the same product size
  • additional macrofracturing and microfracturing within individual fragments from the blasting makes fragments easier to fracture further in the crushing and grinding phases
  • an increased percentage of relatively small mineral ore particles can bypass stages of crushing, decreasing the percentage of total tonnes crushed.

Research has been undertaken to consider blasting techniques which can achieve energy savings through the crushing and grinding process. Savings of up to 30% have been reported. Software packages are also available to assist in designing effective blasting techniques, including analysing and evaluating energy, scatter, vibration, damage and cost.

Ore-sorting and waste removal

Gangue usually occurs in the ore body as large clumps that contain little or no valuable mineral. It is usually harder than the valuable minerals because it usually contains a high concentration of silicates.

Ore sorting and rejection of gangue can help the progressive upgrade of ore concentration in the ore body undergoing comminution. This enables the mill to process material at a very high concentration of ore grade, without low grade material and gangue driving down the average. The sorting criteria should also be integrated with the mine plan and blast design (selective blasting and screening) to ensure that only the right parts of the ore-body are sent to the sorting section, and that they are blasted into a size distribution suited to sorting.

Once mined, gangue can be rejected by progressively processing the ore using a series of separation devices. These devices include ore sorting devices, screens, density separators (such as heavy media circuits or drum separators) and magnetic separators. Optical, radio metric, ex-ray and laser ore sorting devices can also be used for gangue rejection. The effectiveness of each device depends on the ore’s texture, defined by properties including mineralogy, mineral grain size, mineral shape and the association between minerals. A better understanding of ore texture is critical in the selection of a separation device. 

For more information

Coalition for Eco-Efficient Comminution

CEEC reviews and provides access to technical papers, conference papers and presentations from around the world. 

Adopt an integrated energy efficient comminution strategy

Comminution (crushing and grinding) is responsible for at least 40% of total energy usage in mining and mineral processing. Improving flow sheet design strategies reduce the direct and indirect energy usage for comminution through:

  • maximising the gangue rejection ahead of the next downstream step to reduce the amount of material that requires treatment by comminution
  • ensuring the use of most energy efficient crushing technologies ahead of the energy intensive grinding step 
  • ensuring the use of the most energy efficient grinding technologies.

There are many specific energy efficiency strategies for comminution, which are outlined below. Note that these energy efficiency strategies are best applied to the design of ‘greenfield’ comminution circuits, when an increase in capacity is required, or when a change in ore hardness is expected for an existing operating circuit.

Use more energy efficient grinding technologies

Studies show that in some mines the amount of input energy going into the grinding process can be improved by as much as 40% using the latest efficient equipment.Computer simulations using the Discrete Element Method show that most rocks larger than the discharge grate size do not break in the first collision. Instead, these rocks accumulate damage in multiple collisions before breaking, which is an inefficient use of energy.

A wide range of comminution equipment is available for many materials and for many different conditions. The choice of equipment and design of circuits has a significant influence on energy use. For example, the practical energy efficiency of a milling process, defined as the fraction of input energy that is utilised in breakage, is about 30-40% when using semi-autonomous grinding (SAG) equipment. The input energy could be halved, giving an energy efficiency of about 60–80% more, through using an efficient high pressure grinding roll (HPGR) circuit over the traditional semi-autogenous grinding (SAG) comminution circuit.

In addition, the combination of the use of energy efficient crushing and fine grinding equipment helps to reduce energy use by:

  • reducing the primary and secondary recirculating loads, leading to lower power requirements, a smaller volume of ore to handle, and potentially a switch to a smaller mill
  • creating a steeper distribution of particle sizes, leading to easier mineral liberation and more-efficient downstream processing
  • reducing the need to use grinding media which has high embodied energy, e.g. HPGR circuits eliminate the need for high embodied energy grinding media.
  1. Pokrajcic Z and Morrison R (2008) ‘A simulation methodology for the design of eco-efficient comminution circuits’ in Proceedings XXIV IMPC (eds: D Z Wang, C Y Sun, F L Wang, L C Zhang and L Han), vol 1. 
  2. Pokrajcic, Z., Morrison, R.D. and Johnson, N.W. (2009) Designing for a Reduced Carbon Footprint at Greenfield and Operating Comminution Plants. Conference Paper 
  3. Pokrajcic, Z and Morrison, R, 2008. A simulation methodology for the design of eco-efficient comminution circuits, in Proceedings XXIV IMPC (eds: D Z Wang, C Y Sun, F L Wang, L C Zhang and L Han), vol 1
  4. Powell MS and Morrison RD (2006) A new look at Breakage testing, 11th European Symposium on Comminution, 6 p (European  Federation of Chemical Engineers)
  5. Daniel M and Lewis-Gray E (2011) Comminution efficiency attracts attention AusIMM (Opens in a new window) PDF 14.9 MB
  6. Musa F and Morrison RD (2009) A more sustainable approach to assessing comminution efficiency, Minerals Engineering, vol 22, pp 593-601 
  7. Pokrajcic, Z and Morrison, R, 2008. A simulation methodology for the design of eco-efficient comminution circuits, in Proceedings XXIV IMPC (eds: D Z Wang, C Y Sun, F L Wang, L C Zhang and L Han), vol 1.
  8. Pokrajcic Z, Morrison RD and Johnson NW (2009) Designing for a reduced carbon footprint at Greenfield and operating comminution plants in Proceedings Mineral Processing Plant Design, Society for Mining, Metallurgy, and Exploration: Colorado
  9. Powell MS, Benzer H and Mainza AN (2011) Integrating the strengths of SAG and HPGR in flexible circuit designs, Fifth International Conference on Autogenous and Semiautogenous Grinding Technology, Vancouver, Canada, 25-28 September, 2011.and Daniel, M et al (2010) Efficiency, Economics, Energy and Emissions – Emerging Criteria for Comminution Circuit Decision Making
  10. Pokrajcic Z and Morrison R (2008) A simulation methodology for the design of eco-efficient comminution circuits, in Proceedings XXIV IMPC (eds: D Z Wang, C Y Sun, F L Wang, L C Zhang and L Han), vol 1
  11. Powell MS and Bye AR (2009) Beyond mine-to-mill: Circuit design for energy efficient resource utilisation, Proceedings of 10th Mill Operators Conference 2009, The Australasian Institute of Mining and Metallurgy, Adelaide, Australia, 12-14 October 2009, pp. 357-364, ISBN 978-1-921522-12-3 (CSRP Project 67, 2B1 Extension)
  12. Daniel M et al (2010) Efficiency, Economics, Energy and Emissions – Emerging Criteria for Comminution Circuit Decision Making

Select the coarsest possible grind size

The target product size, or grind size, has a large influence on the size and energy use of a comminution circuit. As the product becomes finer, the internal flaws in each particle become fewer, the particles become stronger, and the grinding energy increases.

An alternative approach for the selection of a target product size for multi-mineral ores is the progressive liberation strategy. This strategy involves liberating one mineral or one group of minerals at a time by applying the following concepts:

  • Multiple valuable minerals are grouped, increasing their effective concentration, and enabling the desired level of liberation to be achieved at coarser target product sizes.
  • Fully liberated particles (100% valuable mineral) are recoverable in a flotation process.
  • Particles containing at least 15% valuable mineral by sectional area are recoverable in a flotation process using the appropriate flotation conditions and flotation reagents.

If minerals are sufficiently liberated or recoverable (in composite particles), then they can be separated from the ore before further comminution. This strategy can also be used to remove gangue from the ore, leading to less grinding energy and more efficient separation in downstream processes. This strategy, however, requires a good understanding of the particle composition at different product sizes.

Optimise particle size

The reduction ratios for each successive crushing and grinding process influence the distribution of particle sizes and the energy use of the process. Energy use is relatively low when particle sizes are consistent. Finer particles, being harder, resist breaking and are instead displaced, causing energy to dissipate; they also lead to the generation of slimes. Larger particles reduce grinding efficiency.

Screens and filtering devices help to achieve a more-consistent particle size. A consistent distribution of particle sizes is expected to produce superior flotation performance.

Use more advanced and flexible comminution circuits

Using single comminution circuit with very large semi-autogenous grinding (SAG) mills has enabled companies to economically expand into large, low-grade ore bodies and treat large volumes of ore. A disadvantage of this approach is that comminution becomes less efficient as ore body concentrations decline but there is only one circuit operating. Therefore, many companies have moved to using comminution circuits with at least two (some, more than four) parallel milling circuits. This allows high and low grade ores to be processed simultaneously, but on separate circuits, enabling each grade to be ground closer to its optimal recovery size, increasing grinding efficiency and reducing energy use.

It is possible to optimise, design and build comminution equipment perfectly fitted for each ore body. Advances in modelling, by CSIRO and the University of Queensland, can now assist to determine and optimise the design of the most energy efficient comminution equipment. Research teams have developed theoretical approaches and software packages for modelling different combinations of comminution circuits to minimise overall energy use across the circuit.

Discrete element method (DEM) is increasingly useful as a tool that can help provide fundamental insights into comminution processes and into the behaviour of specific comminution machines.  It can contribute to the design and rapid manufacture of new comminution equipment, improvement of existing equipment, and increasing the operational efficiency of all comminution unit processes.  For example, the DEM modelling can now allow detailed exploration of the particle flow and breakage processes within comminution equipment. It can also assist in developing a clearer and more comprehensive understanding of the detailed processes occurring within.

Improve the efficiency of separation processes

Froth flotation is a method of mineral separation which relies on the different chemical properties of minerals compared to gangue. As such, optimising the chemistry in the flotation cells reduces energy intensity. Energy savings are possible through using more advanced froth flotation technologies and control engineering.

For example, technologies such as the Jameson cell produce smaller bubbles more consistently than previous flotation cells, enabling the process to be more energy efficient. Mixing and adhesion occur more quickly and in a smaller space footprint compared to traditional froth flotation cell. A higher percentage of mineral is recovered, improving the economics of a mine. The Jameson cell also has no need for a motor, air compressor or moving parts. See the Jameson Cell website for more details.

Improvements are also being made in control engineering of flotation systems to achieve further energy efficiency improvements.

Invest in materials movement energy efficiency opportunities

After comminution, materials movement tends to be the next largest area of energy usage, with materials movement consuming more than half of the energy used in mining sectors such as iron ore and bauxite.  Conventional hauling of mineral ore, overburden and waste using diesel powered trucks on gravel roads, increases rolling resistance. Rolling resistance also increases with the weight of a truck.

There are many energy efficiency strategies to improve the fuel efficiency of haul trucks through fleet optimisation and upgrades. There are also alternative material movement strategies to complement haul trucks, including in pit mobile crushers, conveyor systems, overburden slushers, electric draglines, lighter haul trucks and diesel-electric trolley haul trucks.

Some examples of opportunities in this area are outlined below.

Optimise hauling efficiency in existing truck fleets and mines

Actions that can improve the energy efficiency of existing haul truck fleets in mining include:

  • Optimising payload management – Payload management ensures that each haul truck carries the optimum tonnage of material to increase fuel efficiency. In some cases this approach can also reduce the number of trucks required to complete tasks. For example, Thiess implemented payload management systems, identifying energy efficiency opportunities which save up to 117,300 GJ and 8200 tonnes CO2-e emissions per year.
  • Implementing improved driver practices – Improved driver practices, or eco-driving, refers to a system of driving in which optimum fuel economy is achieved by the vehicle operator. The system incorporates a range of driving behaviours such as smoother driving, e.g. gentle acceleration and braking, and driving more slowly with less idling. Fortescue Metals Group quantified the energy costs associated with stopping haul trucks unnecessarily, which equated to 361 kL (13,935 GJ) of diesel per annum for the Caterpillar 777 fleet and 407 kL (15,710 GJ) of diesel per annum for the Terex 3700 AC fleet for a single stop sign per payload cycle. For more information see Improved Driver Practices.
  • Purchasing larger haul trucks – Jellinbah Resources Pty Ltd operates the Jellinbah East Mine in the Bowen Basin of central Queensland. The purchase of larger coal trucks will reduce the number of trucks in a circuit. This will reduce the number of trips to the pit to collect the coal potentially reducing fuel use by 151,893 litres of fuel or 5,863 GJ of energy per year. 
  • Measuring and analysing haul truck energy performance – Downer EDI Mining developed performance indicators that use an equivalent flat haul calculation to account for elevation changes on a specific mine route. The indicators provide a more consistent measure of true energy performance, enabling the company to track energy intensity over time. The Commodore open-cut coal mine in South East Queensland has been used as the pilot site for energy efficiency improvements. Energy intensity of the mine has improved by 18.2% over five years.
  • Benchmarking and comparing performance across the haul truck fleet – Leighton Contractors developed a Best Truck Ratio model to evaluate and benchmark the efficiency of fleet operations across a single site and multiple operations, where the nature of the work undertaken varied greatly. This model provides an indication of how efficient their fleet is in comparison with what is practically and realistically possible. It is providing a rigorous analytical tool which Leighton is using to support decision making processes.

For more information

Analyses of Diesel Use for Mine Haul and Transport Operations 2011

(PDF 1MB)

Department of the Environment and Energy

This case study aims to provide mining companies with examples of comprehensive analyses of diesel use in mining operations used by Fortescue Metals Group Ltd, Downer EDI Mining Pty Ltd and Leighton Contractors Pty Limited. This case study was developed as part of the Energy Efficiency Opportunities program.

Consider energy efficiency when upgrading haulage systems

When upgrading haul truck fleets the following options should be considered:

  • Use lightweight, hybrid diesel electric trucks which are more fuel efficient and can recover energy through regenerative braking on descent into a mine.
  • Use trolley trucks that use tram power lines to access or feed in electricity to enable energy to be recovered as the trolley trucks descend back into the mine. For example, RioTinto, at Rössing Uranium in Namibia, has adapted this idea to diesel electric trucks so they can save fuel and recover energy on their descent into the mine. At this mine, Rio Tinto has invested in overhead wires so that haul trucks with diesel-electric units can draw power like a trolley bus. This reduces fuel consumption with a payload of 182 tonnes from 350 litres an hour to 25 litres an hour. Although it consumes electricity, overall energy savings of up to 30% can be achieved.

Also consider the benefits of complementing the use of haul trucks with the following:

  • Conveyor belt systems – Conveyor belt systems have been shown to be significantly more energy efficient in transporting materials than haul trucks, using about 20% of the energy required by heavy-duty trucks.There is also scope to improve their performance through optimisation using simulation models and improved monitoring and management.
  • In-pit-crushing-conveyor (IPCC) systems – IPCC systems are the most energy efficient systems for hauling ore, overburden and waste from open cut mines. Innovations in IPCC system technologies in the last decade now see IPCC systems being used at most types of open cut mines. It is important to note that IPCC systems do have significantly larger upfront costs however compared to haul trucks.
  • Overburden slushers (OS) instead of electric draglines – An OS uses two winches, one on each side of the open cut, to drag a large bucket across the overburden, then to the top of the mine. Existing draglines can be converted.
  • Improve the efficiency of existing draglines – Electric motors can be upgraded, the ropes and motors strengthened and the bucket and rigging configuration revised to decrease the weight of the system whilst increasing the weight it can carry.

Improve the energy efficiency in product transport

Mineral ores are often transported long distances to mineral processing plants or to port for overseas shipment. There is potential to save energy through using the most energy efficient mode of transport as well as improving the efficiency of the mode chosen.

Conveyor belts across horizontal distances (or close to horizontal) are significantly more energy efficient than trucking on gravel roads. Freight rail also is more efficient than trucking. The design and operation of conveyor belts, trucking, and freight rail themselves can also all be made more energy efficient.

Analysis of freight movements can also lead to fuel efficiencies through improved scheduling and a reduction in stop/start events.

For more information see the Road transport sector page.

For more information

Analyses of Diesel Use for Mine Haul and Transport Operations 2011

(PDF 1MB)

Department of the Environment and Energy

This case study aims to provide mining companies with examples of comprehensive analyses of diesel use in mining operations used by Fortescue Metals Group Ltd, Downer EDI Mining Pty Ltd and Leighton Contractors Pty Limited. This case study was developed as part of the Energy Efficiency Opportunities program.

Implement air ventilation and conditioning opportunities

For underground mines, air ventilation is a significant area of energy usage. Energy savings can also be achieved through ensuring air ventilation supply matches demand, minimising energy use in air and water flows and through reducing the area required to be cooled. Often fan and pumping energy losses are high due to the long distances air and chilled water must be moved. Localised systems using the latest high efficiency air conditioners, fans and pumps can be more efficient.

Maintain and optimise fan system operations

Relatively low cost energy savings can be achieved through maintenance improvements. For example, fan impellers or blades should be regularly cleaned to avoid fouling in dusty environments, which causes static pressure losses.

Energy efficiency savings can also be achieved through ensuring air ventilation supply matches demand. Since air ventilation is a major health and safety issue, most mines run air ventilation systems harder than necessary. Mine ventilation systems are also subject to changing system characteristic curves as the workings move. This means a system that is initially optimised will deviate from this optimum over time.

For more information

Energy Mass Balance: Mining 2010

(PDF 2.2 MB)

Department of the Environment and Energy

This guidance document outlines the key considerations and potential approaches for the development of an energy-mass balance for a mining operation.

Minimise energy use in air and water flows

The largest savings in ventilation come from reducing the area cooled. Often fan and pumping energy losses are high due to the long distances air and chilled water must be moved.

Localised systems using the latest air conditioners, fans and pumps can be more efficient. Reducing air or water flows by even a few percent can offer disproportionately large energy savings, so variable speed controls can achieve large savings.

Researchers are working on lightweight personal cooling units, which may allow space conditioning to be reduced.

For coal mines, the economics of using ventilation exhaust air as an input to on-site electricity generation are also improving. Identifying areas of high flow resistance (pinched ducts or pipes, sharp corners, etc) can also add to savings.

Reduce energy demand and explore waste heat options

As oil prices increase, the traditional diesel generator is becoming expensive to run. Reducing onsite energy demand and recovering waste heat can achieve additional cost effective energy savings.

Demand management

Active demand management can help to avoid the need for investment in generation capacity. For example, slowing pumps, dimming lights and cycling non-essential air conditioners and other equipment can limit peak demand. Insulation and shading of buildings and equipment can also cut peak cooling loads. A lot of lighting is needed as often mines are run as 24 hour a day operations. Moving to more efficient lighting is a relatively simple step operationally that can yield rapid returns on investment to help fund other energy efficiency investments.

The energy efficiency of offices, staff facilities and accommodation can be maximised by using high efficiency lighting,  HVAC equipment and hot water systems. Selection of efficient office equipment and appropriate management of it can offer substantial savings.

In hot locations, additional insulation, shading, management of air leakage and light-coloured buildings can improve comfort and cut energy costs. Paying attention to thermal bridging (for example, heat leaking around insulation via metal framing connecting internal and external walls) can also pay large dividends. A thermal imaging camera can be used to identify heat leaks.

For more information, see Commercial buildings.

Waste heat recovery

Waste heat can be recovered to provide both electricity and steam. For example, Xstrata Copper has invested in waste heat recovery at its Mount Isa Mines copper smelter to produce steam and electricity to produce 77,000 MWh in 2009 thereby avoiding the consumption of 1.15 PJ of natural gas. Iluka Resources Limited’s South West synthetic rutile plant incorporates a waste heat recovery plant (WHRP) which uses the waste heat from the kiln to generate electricity for the rest of the operation. Kiln off gases are used to generate steam which drives a steam turbine generator that powers the downstream physical and chemical separation stages of the plant. Waste heat can also be recovered to provide cooling (via absorption or adsorption chillers).

  1. Queensland Resources Council (2012) The Queensland Resources Council’s Contribution to Reducing Carbon Emissions. QRC
  2. Department of Resources, Energy and Tourism (2011) Iluka Resources: Case study

Implement technology-specific energy-efficiency opportunities

Further energy efficiency opportunities can be achieved by implementing improvements in specific technologies, such as motors, pumps and fans, lighting and air compressor systems. These systems consume a significant amount of energy in mining and mineral processing.

For example, to improve their pumps, Xstrata Copper replaced ‘two thickener underflow pumps at the Mount Isa Mines copper smelter to improve pumping efficiency thereby reducing power consumption by approximately 1,325 GJ per annum. Xstrata also replaced ‘compressor cooling water pumps at the Xstrata Copper Townsville Refinery to deliver an estimate energy saving of 630 GJ per annum.

Compressed air systems are used to blast coal and to operate stopers, mucking machines and other equipment requiring pressured air flows. Compressed air energy efficiency can be improved by adhering to maintenance schedules, identifying and fixing leaks, using variable speed drives and selecting compressed air systems where they can run as close as possible to full load.

Implement energy/water efficiency nexus opportunities

Investments in resource characterisation, smart blasting and ore concentration upgrade can save water as well as energy in the comminution and mineral processing stages.

Where dewatering is required, the energy efficiency of pumping systems can be optimised by using efficient motors and pumps, using smooth pipes with a large diameter, and running the pumps continuously at low speed instead of short periods at high flow. In open-cut mines, rather that pumping water from the bottom of the mine up to the top, the water can be put into dust-suppression water tankers at the bottom, which tankers can use to spray water while driving uphill (tankers usually spray while driving downhill).

In underground mines, the energy used for dewatering can be partly offset by using a simple turbine to convert the potential energy of the down-flowing chilled water used for air-cooling or down-flowing water used for the mining process. Xstrata has invested in an underground Pelton Wheel generator at the Xstrata Mount Isa Mines copper operations. This 'acts as small hydro power station recovering potential energy from water dropped 800 metres underground. The generator added 2,500 MWh of electricity to the site’s power network in 2009 thereby avoiding the consumption of 37,500 GJ of natural gas.'

For more information, see Pumps and fans.

  1. Willier A (1977) Recovery of Energy from Water Going Down Mine Shafts. Journal of the South African Institute of Mining and Metallurgy. Pp183-186
  2. Queensland Resources Council (2010) The Queensland resource sector’s contribution to reducing carbon emissions