Energy Efficiency

Electricity consumption in mineral extraction and processing is significant, representing at a minimum 10% of the cost of production for mining operations in Canada. Mining extraction alone represents 60% of the energy consumption, while ore concentration at the mill is responsible for the difference. In addition to electricity, the energy consumption of a site includes electricity and fuels, such as natural gas, propane gas and diesel fuel. The major energy consuming processes in a Canadian mechanized mine are ventilation, the associated heating and cooling of intake air as well as ore transportation (mobile diesel equipment)

The Energy Efficiency research and innovation element addresses these issues directly under a set of three R&D themes, including Ventilation Efficiency, the Green Mining Vehicle Roadmap and the Diesel Engine Certification Program for underground mines.

Ventilation Efficiency

Heating, Ventilation & Air Conditioning (HVAC) can be the largest power user in underground mines and should operate efficiently. Using power creates emissions and represents a considerable expense. Mines can use 15-20 tonnes of air to mine 1 tonne of ore.

HVAC is required in mines to provide a suitable working environment for workers and machinery. Air is needed to dilute and remove harmful contaminants. Respirable dust is produced when breaking rock. Soot particles are a by-product of using diesel equipment. Dangerous gases can come from the rock mass (strata), mobile vehicle exhausts and explosives. Hot, or cold, conditions can exist due to the climate, using large equipment, the strata or natural compression of the air in a deep mine.

Ventilation Control

Managing the distribution of ventilation is complex as underground mines are never static. Ventilation circuits continually grow and change as the mine expands. Air may have to travel over 10km through numerous tunnels to each work place and old tunnels become potential leakage routes. The mining process is also very dynamic. The locations needing ventilation vary on a daily basis.

Flexible, robust and comprehensive HVAC control systems still need some development. Efficient ventilation control has many benefits but can be expensive to implement and maintain. Production rates and continuity of specific operations also vary greatly with mining cycles.

Delivering the right amount of air only when and where it is required in real-time can dramatically reduce energy requirements or allow increased production. Unlike a surface manufacturing plant, a mine recreates a new set of working locations every few years. Exactly matching air supply to instant demands, while ensuring worker safety, requires advanced monitoring and control systems throughout the mine.

Monitoring technology has to progress from a passive historical role to a proactive control function. Vehicles and personnel can be tracked, gas concentrations and airflows can be monitored, fans can be turned on or off and doors can be opened or closed. Surface technologies may use different communication architecture and may not be suited to harsh mine environments.

Addressing Demand

Eliminating the production of one contaminant can reduce its requirements of the HVAC systems but may not generate an overall benefit.

To make a more informed decision, production based event simulation can now be used to anticipate the benefit of a technology, such as the replacement of diesel equipment, on the whole economics of the mining process.

Currently the major demands for ventilation are to control diesel exhaust and heat loads, or thermal conditions, in a mine. Consequently, multi-faceted approaches are required to look at the control of each relative requirement and the logistics of any technological change to make the most dramatic changes in the actual volumes of air required.

The Green Mining Vehicles – Green Energy Roadmap

Owing to ever stricter workplace health regulations attached to diesel particulate matter, rising oil prices, and an emphasis on cutting carbon cost and emissions, the drive to ever cleaner diesel and the application of alternate energies has become more prominent in the mining sector. 

CanmetMINING’s expertise is being applied to help industry meet ongoing reduction in diesel engine emissions exposure values.  Alternatively, to keep energy costs under control and keep pace with surface vehicle clean energy adoption, CanmetMINING is helping mining companies plan for various alternative scenarios and apply a wide range of alternative vehicle power and related energy efficiency means. 

There are a large number of greener energy alternatives that are technologically ready for consideration, the most advanced and practical for mining vehicles are: diesel-rechargeable battery and hydrogen fuel cell-rechargeable battery hybrid power plants which have already been tested by CanmetMINING in underground loaders, with regulatory requirements being addressed.  Lithium ion batteries are also making headway, especially for smaller vehicle power plants.

In order to facilitate continuous cleaner diesel developments and make alternative power changeover a reality, a focused approach to support and make ready cleaner power technology and related energy efficiency (ventilation, refrigeration) in the key area of mine production and support vehicles is needed.  This will provide industry with a strategic and specific set of fully developed options, including a thorough review of regulatory impact.

CanmetMINING in partnership with key technology suppliers and mining stakeholders is facilitating an industry initiative called the Green Mining Vehicles-Green Energy Road Map to provide the necessary technological, financial and regulatory solutions for industry to make decisions on the adoption of the most advantageous cleaner diesel, and green power options for their operations.

The two year time horizon for the Road Map will see the completion of a number of studies and power plant projects, under the direction of mining companies.

Simply outlined, the Road Map will first establish the status and gaps of relevant technologies in current applications which will frame the basis upon which corporate and industry targets for energy efficiency and greener energy performance can be defined.  From this point, the key technology alternatives and related energy efficiency aspects can be defined for adoption, designed and tested to need (operational and regulatory), and the management systems for implementation specified.

Diesel Technology

Diesel equipment is extensively used in Canadian underground mines for the reasons of higher productivity and flexibility. The Diesel Emissions Research Laboratory was established in early seventy’s to test and certify diesel engines, to conduct research and provide expertise to mining companies, regulators and equipment manufacturers. Because of energy efficient vehicle requirements, and recent health hazard from diesel exhaust, a greater efforts are being made to reduce worker’s exposure to diesel emissions by promoting clean energy efficient technologies. Some of the current activities are:

• Research and development on diesel emissions control technologies with industry partners, assists the equipment manufacturers with the design and development of new products and alternative energy, fuels for the underground mining industry. Real-world vehicle duty cycles can be simulated in laboratory on our engine dynamometer, greatly reducing costs and complexity associated with field testing.
• Technical advisory role in the development of diesel emission standards in cooperation with Provinces/Territories, regulators, and industry.
• Research and development on particle number and size distribution for reduction in the exhaust emission in cooperation with national and international partners.
• Field evaluation of engine emissions and emission control technologies.

Energy Efficient Rock Fragmentation

The mine-to-mill holistic approach is an entire mining and processing optimization system from the blasting to the comminution circuit and attempts in economic and energy saving opportunities. More than 45% of the energy used in a typical open-pit mine operation is spent in rock size reduction and, worldwide, comminution consumes about 3% of the world electrical energy. Distribution of energy study shows that blasting accounts for 3 – 5%, crushing for 5 – 7%, and grinding for 90% of the total energy used. Energy efficiency is less than 1% in industrial grinding processes and it was shown by a number of studies that most of the energy is dissipated as heat in the rock, equipment and water and in the surrounding atmosphere. One of the causes of this high inefficiency of the grinding mill, which is targeted in this project, is the high variability of the run-of-mine ore hardness and size distribution feeding the grinding process. This natural variability of the run-of-mine ore is amplified significantly by ore segregation in muck piles and silos where the ore is accumulated before being transferred to the grinding process. The objective of the project is to develop, assess and test an integrated tool to track and monitor the hardness and the size distribution of the run-of-mine ore feeding the autogenous or semi-autogenous grinding mills and to adjust accordingly the feed ore preparation steps (blasting, crushing and blending) and the mill operating parameters (throughput and percent solids) for energy saving and increased productivity of the autogenous or semi-autogenous grinding mills.