African Mines are in Good Condition – and Safer

Ten years ago the Projects division of BBE had just completed two refrigeration and air cooling installations at AngloGold Ashanti’s Obuasi Mine in Ghana, and were busy with the first of two new installations at Acacia Mining’s Bulyanhulu Mine in Tanzania.

In the ensuing ten years BBE have installed more than 200 MW of cooling power into the hottest mines on the continent, in some of the hottest climates, providing safe and comfortable working conditions in the underground mining operations.

BBE, with its full spectrum of consultancy, automation, energy and projects divisions has been at the forefront of developing ventilation and cooling system technologies in the mining industry for decades, providing professional engineering support in the specialised field of mine ventilation and cooling, designing and selecting the optimum combination of equipment to suit each mine’s particular life-of-mine circumstances.

BBE have designed, supplied and built mine refrigeration and air-cooling systems across the African continent and beyond, on surface and underground, in Ghana, Tanzania, Mali, Zambia, USA, Canada, Brazil, Australia and of course their home country, South Africa.

Each mine, with its unique combination of location, climate, orebody type and mining method demands its own cooling solution. As an independent organisation, BBE’s professional engineers are able to offer unbiased, bespoke solutions utilising the optimum combination of available equipment.

The engineering designs begin with cooling systems at concept level where all aspects of energy efficiency and cooling efficacy are analysed to determine the best fit-for-purpose solution. Then equipment selection and specifications are detailed and taken through to either an EPCM-style project or to a complete design-and-build turnkey package.

In an era of rapid development of the global economy, the energy dependence is increasing rapidly. As the shallow mineral resources on Earth’s surface are being depleted, countries worldwide have successively begun to mine deep resources. As the mining depth increases, the virgin rock temperature increases, and the thermal consequences of the ground temperatures and other factors are amplified.

Ventilation and cooling systems are among the most important functions in a mining operation. Since ventilation directly affects the health and safety of employees working underground, mine owners take the regulation of air flow through a mine very seriously. Yet some may not realize how changes to ventilation and cooling practices can significantly – and positively – benefit the bottom line. The classic approach to ventilating and cooling the entire mine all of the time is a simplistic extravagance.

The rising costs of ventilating and cooling mines, safely and efficiently, dictate that operators have to implement optimized energy management and control strategies. Ventilation-on-demand and cooling-on-demand strategies have the potential to reduce both the capital and operating costs of mine ventilation and cooling systems, and the mechanisms required are technically feasible.

Reflecting on 30 years of business, BBE has a lot to be proud of, not only for its achievement in becoming a world leader in mine ventilation and cooling, but for remaining a proudly independent professional outfit built on vast experience.

Today, BBE comprises a team of well over 100 experienced professional consulting and project engineers, who are leaders in mine ventilation, refrigeration and cooling practices; measurement and control of underground pollutants (dust, diesel, methane, radiation, etc.); energy optimisation and energy recovery; and computer modelling and software for ventilation and cooling networks.

As underground mines reach greater depths, higher temperatures, higher humidity, and more gas emissions are encountered. This becomes a topic of interest to various audiences with very different viewpoints. Workers in the mines expect healthy and safe working conditions with an acceptable comfort level for a typically heavy workload. Mining operators wish to comply with regulations while minimizing the cost of investment and operation. Mining industry regulatory organizations demand compliance with standards for safety and health. Environmental and workers’ advocates wish to see improvements in working conditions as well as lower emission standards. Mining engineers try to design a mine within the constraints of all of the above.

Profitable exploitation must be secured amid the factors of ever-increasing energy costs, stricter conditions, and lower tolerance levels to health risks and accidents. In addition, ventilation engineers and technicians strategize to meet the demands of all parties and to provide safe and healthy working conditions underground at a minimum cost. This balancing act requires intimate familiarity with the nature of geology and the ore deposit as well as their interaction with the engineered mining operation.

The main purpose of mine ventilation systems is to maintain thermal comfort – and thereby improve safety – of underground personnel, remove heat from equipment, dilute mine contaminants, and provide fresh air for personnel to breathe. Underground mines need to be equipped with accurate, real-time, and intrinsically safe monitoring systems to be able to continuously assess the condition of a mine ventilation system. Underground mine workforce safety and workplace productivity rely significantly on the performance of mine ventilation and monitoring systems.

Ventilation within any type of underground mine functions in order to introduce fresh air into the work space of the workers, while simultaneously removing contaminated air from the same location. The removal of such air contaminants, heat, dust and gases, is also particularly important in maintaining an overall safe and healthy environment. The basic components of any type of mine ventilation system involve a combination of pipes, ducts, fans, cooling and heating systems, and occasionally air cleaning equipment.

Due to the extreme environment, underground mining operations make use of some of the largest ventilation and cooling systems in the world, incorporating  several types of cooling technology, such as evaporative condensers, mechanical refrigeration plants, pre-cooling towers and bulk air coolers, in order to ensure a safe mine temperature.

These cooling systems typically work by producing chilled water, occasionally ice, to reduce the temperature of the air entering the mine, or to be sent into the mine to reduce the ambient temperature within the mine. The systems can be installed on the surface, underground, or a combination of both, depending on the depth of the mine and various, logistical factors.

Undoubtedly, Africa is a hot continent. Even on surface ambient conditions can be uncomfortable, unproductive and even unsafe. And it only takes a short excursion underground where the additional heat from virgin rock and mobile equipment demand some form of a cooling system.

Equipped with a professional team of specialist engineers who are world leaders in mine ventilation, refrigeration and cooling, measurement and control of underground pollutants, energy optimisation and ventilation network simulation software, BBE Projects has built an excellent international reputation since inception as it is able to undertake a full range of projects from greenfield sites to plant extensions and upgrades, while offering optimal solutions using the best combination of available equipment, tailor-made to each client’s specific requirements.

Recent and current projects include a pair of refrigeration and surface bulk air cooling (BAC) stations at a mine in Mali; a surface refrigeration and underground BAC for a mine in Barberton, Mpumalanga province, South Africa; an extension to a refrigeration plant supplying a large surface BAC at a platinum mine near Rustenburg, South Africa; an underground plant and associated BACs at a large copper mine in South Africa; an underground plant, 2 600m below surface, supplying cold water to a closed-circuit network of cooling coils; a new surface refrigeration plant and BAC supplying cold air for a dedicated cold hole into a mine in Ghana; and construction is well-advanced for a similar facility at a diamond mine in Limpopo province, South Africa.

Although the building blocks appear similar, each system is discretely tailor-made and the operating parameters carefully tuned to suit each mine’s unique situational and evolving circumstances. For full-on turnkey packages, BBE Projects are familiar with logistics across and around the African continent.

BBE Projects has a long history of success on the African continent and its experience and expertise have been greatly bolstered by being part of the larger BBE group with which it shares all the values, the best staff, technologies and equipment on the continent that enables them to responsibly continue delivering excellence across the board and giving its clients a world class service, while confidently looking forward to another decade of not only providing efficient and economical solutions but also delivering exceptional and innovative professional engineering services wherever your hotspot is located.