Mining and Explosives
Early July is peak fireworks season in North America. Between Canada Day on July 1 and the Fourth of July celebrations in the United States, more than 100 million kilograms of fireworks explode in our skies, to the delight of onlookers celebrating.
But these spectacular fireworks represent a small fraction of the explosives, propellants and pyrotechnics that are used in a wide variety of applications everyday in Canada. Explosives are vital to the economy of Canada and the well-being of Canadians.
"Explosives are chemicals that can react in a self-sustained manner. In other words, there is no need for oxygen from ambient air," explains Jean-Luc Arpin, Canada's Chief Inspector of Explosives. "They are either molecular explosives or are a mixture of a fuel, for example aluminium or magnesium powders or carbon, and an oxidizer, such as potassium or ammonium nitrate."
According to the Canadian Explosives Research Laboratory, explosives are used by the mining industry to extract ore and discover orebodies. They are also used by oil and gas industries to build pipelines, the forestry sector to build roads and the construction industry to build infrastructure. The aerospace industry needs explosives to fuel the rockets that lift satellites into space. The propellants in car air bags and the control of avalanches also require explosives, and there are any more uses.
Canada is one of the largest manufacturers and users of commercial explosives, along with the United States, Australia, South Africa and China. The European Union is a smaller player relative to such countries. From a technology standpoint, Canada is one of the leaders, said Arpin — each year approximately 360,000 tonnes of commercial blasting explosives are manufactured and used here.
"Explosives are made to explode (detonate or deflagrate), whereas fireworks are formulated to create pyrotechnic effects using light, sound, heat and delay" said Arpin.
Raw materials in fireworks
The first fireworks were created in China over 1,000 years ago by mixing saltpetre (potassium nitrate), sulfur and charcoal to produce a black, flaky powder – the first "gunpowder." Today, gunpowder is still used as a propellant for fireworks, along with a wide range of raw materials to impart assorted colours and effects.
"The colours in fireworks are generated by the presence of metals such as copper, aluminium, magnesium, strontium and more," said Arpin. Copper compounds produce blue fireworks; aluminum makes silver and white flames and sparks; magnesium burns a very bright white; and strontium salts give fireworks their red colour.
Explosives and mining
Drill and blast mining is a common method used to break up 'benches' of rock in order to send the smaller pieces of rock containing ore to the processing plant to further separate the valuable ore from the waste rock. As the name suggests, holes are drilled into a section of rock – either above or below ground – and explosives placed in the drill holes.
The volume of explosive needed varies greatly between mine sites, depending on the mining method used as well as the rock type and hardness. For example, StrataGold Corporation's Eagle Gold Project, in Central Yukon, will use approximately 6,000 tonnes of explosives each year, according to an Explosives Management Plan that the company prepared and submitted to the Department of Energy, Mines and Resources and the Yukon Water Board.
Mining companies carefully monitor the amount of explosives used to extract each unit of ore. The goal is to use as little explosive as possible and send as little waste rock through the processing plant as possible, to increase productivity, reduce costs and improve environmental performance through better energy efficiency.
A large Canadian mining company, Teck Resources, tracks the movement of rock and ore during a blast using innovative sensors the size of a softball. The areas with more valuable ore are mapped before the blast, but can move during the blast. To ensure that the rocks and shovels are picking up the most valuable rock after the explosion, Teck Resources workers drop colourful, ball-shaped sensors into drill holes prior to detonation. Nestled inside each ball, protected by the durable outer casing and a shock-absorbing liquid inside, is a sensor that transmits its location. After the blast, handheld scanners determine where the balls have moved, and those data points are used to create a three-dimensional picture of how the ore body has shifted during blasting.
Safety and security
Explosives are serious business and potentially hazardous. As a result, the production, distribution, trade, movement and use of explosives in Canada is highly regulated with all levels of government having important roles to play. The provinces and territories regulate the use of explosives, specifically where mines and quarries are concerned with a focus on worker health and safety.
An example of using high-tech instruments to track and monitor the movement of ore before and after blasting
Where explosive terminology, storage or standards are concerned, provincial and territorial regulations usually link to the Explosives Act or other guidelines published by the federal government. Municipal bylaws regarding permissible fireworks often direct users to the List of Authorized Explosives, care of Natural Resources Canada.
The Explosives Act, which covers the issuing of licences, permits and certificates to facilities that store, import, export, manufacture, test and sell explosives, is supported by an inspection program, a research laboratory and regulations to control explosives and chemicals that could be used to make explosives.
The next time you light that Roman candle consider the larger role that more powerful explosives play in supporting the mining sector's efforts to extract the minerals we need to make those fireworks, and all the other metal bearing products we rely on every day.