It’s broadly accepted that the mining sector has to find a more sustainable way forward and not just try to counter the effects of global warming. According to the UN, the global population is set to increase from today’s 7.3 billion to 9.7 billion in 2050, fuelling the need for raw materials. Yet declining productivity, rising costs, pushback from governments and, in many cases a loss of public confidence are hampering the industry’s ability to meet this demand.
Finding methods and technologies that are cleaner, more popular with governments and citizens, but don’t place additional pressure on the bottom line is a major challenge. Some progress has been made over the past few years, for instance, with liquid membrane emulsion techniques which are increasingly proving their worth in separating metals from toxic wastewater. But a recently developed technique from Nippon Dragon Resources – a Canadian junior gold miner – looks to be one of the most significant breakthroughs yet.
The company is in the business of mining ‘high-grade, narrow vein precious metal deposits’, which is pretty much a necessity in an industry where the easy high-grade gold has been mined already and the quality ore remaining is difficult to reach. Although accessing these narrow veins is possible, it is very hard to do cheaply and without producing large amounts of waste. A new technique called thermal fragmentation, unveiled last November, may be able to do the job, and be a greener method.
Waste not want not
Thermal fragmentation has been in development since the early 2000s but the technique really came into maturity around seven years ago. Essentially, it involves using heat to shatter or ‘spall’ rocks. A conventional drill head creates a 150mm pilot hole in the mineralised structure and a thermal head is placed in the hole. The thermal head is ignited and compressed air pumped in to create a thermal cushion which slowly expands the pilot hole – a maximum width of 1,200mm is achievable in around ten minutes. From there the ore can be extracted with relative ease.
The method is superior to existing methods in a number of ways. Firstly, it calls for 4%-500% less dilution than shrinkage mining and it doesn’t require explosives, so little wall damage is caused. As the process produces only small amounts of waste, ore-handling and treatment costs are greatly reduced and, requiring only a two-man team drives them downfurther. All of these increases in efficiency add up to a considerable environmental benefit.
"There are a lot of explosives in conventional methods but when you talk about using those methods to extract narrow veins you have lots of problems with your dilution and you lose your grades," says Jean-Yves Therien, vice-president of development at Nippon Dragon Resources. "So the development of the technology was based on that…We don’t need crushers, you have much less rock to move, you reduce the energy consumption and also have less environmental impact. We are just extracting what we need to extract."
Rocmec 1: the test bed
Nippon Dragon’s main prospect is Rocmec 1 in the province of Quebec, and consists of a 100m-deep shaft and an 844m decline, with access points at 50m, 90m, 100m and 130m. The property is reported to hold 125,000oz in measured gold reserves and 360,000oz of inferred resources. According to a statement from the management, the project is ‘shovel ready’ , and due to start producing this year.
It was at this site that, back in 2007, Rocmec, as Nippon Dragon was then known, began testing thermal fragmentation in order to hone the technique and get a better idea of the quality of gold ore that lay in the prospect. It also employed the shrinkage method – drilling upwards through the rock – and compared the results, which showed that when extracting a 40m by 20m block of ore, thermal fragmentation removed 1,120t of rock, while the shrinkage method managed 4,032t. In addition, while shrinkage employed a dilution ratio of 260%, thermal fragmentation required 0%.
"The figure above shows that approximately four times less rock needs to be mined for the equivalent mineralised content. This innovative method of extraction allows mine operators to solely extract mineralised zones thus significantly reducing dilution factors and as a result, optimising mine operations," concludes the technical report.
The technology has been a long time in development but gained its major breakthroughs in 2015. In March, the company conducted three successful surface demonstrations in Japan with representatives of heavy industry, as well as the Japanese Government in attendance.
In April, Nippon Dragon entered into an agreement with Australian mining equipment provider Safescape for the distribution of thermal fragmentation equipment in Australia, New Zealand, Papua New Guinea, Indonesia and the Philippines. This was followed up in November by signing an exclusive agreement with mining contractor Don Bourgeois and Sons for the use and distribution of thermal fragmentation kits. The agreement covers the whole of Canada and will see profits shared equally between the two organisations.
A hard sell for a conservative industry
For Therien, such agreements have been hard fought. As well as being quite resistant to change, the mining industry’s high premium on secrecy has made it difficult to market thermal fragmentation. Firms trialling the technology often want the results to be kept private, which is hardly ideal when trying to validate the qualities of your new product. However, a partnership formed in September with IBM, to develop a cloud-based system that will collect data from sensors on the thermal fragmentation units, should provide convincing numbers that can be shared with potential customers.
"We’ve pushed hard to have recognition and we did lot of work in the past on different mines," Therien says. "The thing is we always get stuck with a confidential agreement because mining is not an open industry. For us it’s a major challenge. Normal investors [from outside the mining sector] look at it and think it should be like the software industry. They say, ‘if [thermal fragmentation] is so good then surely everyone should be using it.’"
In Therien’s view this is part of a mutual suspicion between mining companies that has to be overcome. They simply aren’t accustomed to working together to solve industry-wide problems, which is exacerbated by the present low profit environment that is making companies increasingly inward-looking.
"We are making lots of progress and we expect, not so far from now, there will be companies around the world who say that [Nippon Dragon] are helping to solve their challenge," He adds.
"Our technology is a tool that should be in every mine. It can’t save every company in the world and you don’t use our tool to do everything, but you should have one because one day you might need it."