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'Mohr' muscle, fragmentation, less emissions in Braeside trials

Blast trials at a southern Queensland quarry have delivered encouraging results for a potentially safer, environmentally friendlier explosive. Braeside Quarries owner Joanne Payne discusses the possible benefits of the award-winning crumbed rubber product for the extractive industry.

The IQA Gold Environment Award recognises a site’s contribution towards the advancement of environmental management in the extractive industry.

In 2017, the award, sponsored by Groundwork Plus, was conferred on Braeside Quarries, about 85km south of Toowoomba, in southern Queensland.

The quarry, independently owned by Joanne Payne, received the award for its successful use and testing of a new explosive utilising recycled rubber as a waterproof, safe and environmentally friendly alternative to ammonium nitrate fuel oil (ANFO) and emulsion products.

"Mohrpower product is safer to handle and can be transported more securely than traditional explosives."
Joanne Payne, the general manager of Sequel Drill & Blast and owner of Braeside Quarries.

This met the award’s criteria that stakeholders in the extractive industry should strive towards reducing their carbon footprints and greenhouse gas emissions through innovative, original, cost-effective and transferable projects and initiatives.

“Braeside started as a greenfield site in 2007 and it has been steadily increasing its footprint in the marketplace,” Payne said. “We manufacture a full range of products – roadbase, pugged and unpugged, blue metal products which can be pre-coated for road construction, and concrete aggregates. All other types of quarry materials are produced for sale. We have a small staff of five people.

“The quarry is a registered Key Resource Area site with a licence to extract up to a million tonnes per year. The current regional market has been limited, but is slowly increasing. The urban encroachment of metropolitan quarries will make Braeside a significant resource in years to come.”

Braeside Quarries has for several years conducted trials on its site in conjunction with crumbed rubber producer and recycler Chip Tyre. A new company was formed as the owner of the Mohrpower range of products, Blew Chip, to research, develop and deliver the ingredients for a crumbed rubber explosive.

Sequel Drill & Blast has a distributorship agreement with Blew Chip to market the explosive, and is also the only company licensed to handle, store and deliver the product. Braeside Quarries allows the trials and, in combination with Sequel, manages the drill and blast process within the quarry.

Diesel substitute

The concept of crumbed rubber explosives is not new to the extractive industry. Rio Tinto pioneered, experimented and patented the use of crumbed rubber to replace diesel in its explosives in 1994. However, despite cost-efficient results, the new technology didn’t earn widespread industry interest and the patent lapsed.

Mohrpower is a waterproof, safe and eco-friendly alternative to ANFO and emulsion products.
Mohrpower is a waterproof, safe and eco-friendly alternative to ANFO and emulsion products.

“My understanding is that the product was proved up by one of the majors,” Payne said, “but because they had all the infrastructure and trucks to use traditional types of explosives, at the time it was not commercially viable to invest any further funds.”

It was not until 2008 that the concept was revisited. David Mohr, the founder of Chip Tyre, applied for a Queensland Government grant to develop an improved version of crumbed rubber explosives.

Alan Twomey, the man assigned to review the grant application, met with Mohr to discuss the proposal. Twomey, a research scientist in food and waste to energy applications, and the head of his own consultancy BioAust Energy, subsequently partnered with Mohr to establish Blew Chip.

In 2015 the pair secured research funding from Tyre Stewardship Australia, a peak body of representatives from the tyre supply chain, to further trial and develop the product.1 It was at this point that Sequel Drill & Blast and Braeside Quarries entered the picture.

“We were approached by Chip Tyre, which was looking for ways to utilise recycled tyres, with a view to exporting to China,” Payne said. “In their research, they’d stumbled across the paperwork for previous trials using rubber. They obtained the patents and asked for Sequel’s assistance in developing a product in the explosives industry. As Chip Tyres did not have the licences and expertise in regard to the explosives, it was important for them to partner with Sequel and with Braeside quarry as the testing mechanism.

“We have developed the product with Blew Chip since the beginning. We have conducted all of the field trials through Braeside quarry right through from naming the product – Mohrpower – to the approval process.”

Similar densities, strength

According to Payne, the Mohrpower crumbed rubber explosive is distinctive because it maintains a density similar to ANFO and the bulk strength of emulsion products while still being exposed to water.

A bird’s eye view of the test site for the Mohrpower explosive at Braeside Quarry.
A bird’s eye view of the test site for the Mohrpower explosive at Braeside Quarry.

“In broad terms, ANFO is only suitable for dry holes and emulsion is used for wet holes,” she explained. “In our first trials, we proved the concept of eliminating the fuel from ANFO, thereby substituting it with rubber.

“While this was extremely successful, the cost is slightly higher than ANFO on a bench cubic metre (BCM) costing. The next stage was to waterproof the AN to make it equal to emulsion-type products. This is where the savings kick in because we can produce a significantly cheaper explosive.”

The aim was to develop an explosive that was fossil-free by substituting the diesel with recycled rubber and waterproofing the product with a polymer. The rubber, which was impregnated with iron, acted as a bulking agent that reduced the quantity of the AN by 22 per cent. The polymer would then attract the rubber to the AN to eliminate separation of the two products.

Further development was undertaken to waterproof the explosive by coating each grain of AN/rubber blend. The end result is an explosive that is a very good substitute for ANFO and whose density is lower than emulsion and very similar to AN.

Braeside and Sequel reported very similar fragmentation results between the crumbed rubber product and the emulsion product, as the former was delivered into the hole at a density of 0.9.

A blast powered by the Mohrpower test explosive.
A blast powered by the Mohrpower test explosive.

With a bulk strength similar to emulsion, the overall cost per BCM is therefore greatly reduced. The density can also be controlled through the addition of more iron into the rubber blend.

“In layman’s terms,” Payne said, “the density of the emulsion is around 1.2, so the usage of Mohpower results in using considerably less, resulting in a significant cost saving.”

Mohrpower is also a potentially safer product compared to regular explosives.

“Due to the elimination of diesel fuel, the flash point is lower and therefore the product is safer for the handler,” Payne said. “Mohrpower can be used in a much higher temperature ground, due to the lower flash point. Alternatively, the product can be used in much colder temperatures because the rubber does not freeze, whereas diesel can freeze at low temperatures.”

The reduction of the flash point also means the Mohrpower product is safer to handle and can be transported more securely than traditional explosives. There are also potential savings to be gained from manufacturing the product on-site (rather than the delivery of explosives) and from reducing the storage of conventional diesel explosives in a quarry.

Payne is also pleased that the trial achieved a goal to eliminate noxious gases that can be generated from water damage to ANFO.

The crater after the successful blast.
The crater after the successful blast.

“Noxious gases are a huge problem in the mining industry today,” she said. “We are confident that we can reduce and possibly eliminate any noxious gases.”

Payne believes there is huge potential for Mohrpower to be used in the quarrying industry, and for any other mining application worldwide. However, it is contingent on further tests of the product on other rock types and in different locations before a marketing and feasibility strategy is implemented.

“All of our trials have been conducted in the one type of ground at Braeside Quarries, and we have noticed a significant difference in fragmentation and heave in the dry hole product compared to straight ANFO,” Payne explained. “With the Mohrpower wet, we have very similar results to the emulsion products.

“We continually are looking for improvements in the products. However, the quarry is limited in its capacity due to being a small regional site. The approval process has been quite difficult and is continually evolving along with the product. Trials in different locations and rock types will be necessary to ensure our results, particularly with the elimination of noxious gases, are transferable to other sites.”

Gold environmental award

Braeside Quarries submitted the results from the recycled crumbed rubber explosives to the IQA for the Groundwork Plus Gold Environment Award in August 2017.

Joanne Payne (left) receives the Golden Environment Award from Groundwork Plus director Tegan Smith.
Joanne Payne (left) receives the Golden Environment Award from Groundwork Plus director Tegan Smith.

Applications for the award were considered by a panel of IQA and Groundwork Plus representatives, and Groundwork Plus director Tegan Smith presented Braeside Quarries with the award – which comprised a framed certificate and an engraved gold plated sprig of eucalypt leaves – at the IQA’s 60th national conference in Toowoomba on 6 October, 2017.

Payne accepted the Gold Environment Award on behalf of Braeside Quarries. It was the second award claimed by Braeside for the crumbed rubber product, after it also received the Cement Concrete Aggregate Australia Environmental Innovation Award.

“I was surprised we won,” Payne said of the Gold Environmental Award.

“I was aware of some significant projects carried out within the industry, all very worthy of contributing greatly to the bettering of our industry as a whole – and more pointedly, improving environmental awareness in our workplaces.

“It was an honour to be chosen out of a very illustrious group of colleagues. It has been a joint effort between Braeside, Sequel and Blew Chip. Winning the award validated the passion we have for the industry.

“It also gave our staff members pride in the work they have completed. This involves our quarry operators, co-operation from our site senior executive, Sequel shotfirers and technical personnel and the delivery of the rubber crumb and polymers from Blew Chip.

“It also raises awareness within the industry of our work. Now that the industry knows about the product, we look forward to trialling and demonstrating it to other professional quarry operators, once we have the final approval to do so.”

Payne encourages other quarries and quarry-related businesses to nominate their projects for consideration in the IQA’s annual awards.

“The sharing of new information and new technologies is vital for the continuous improvement of our industry,” Payne said. “By nominating projects that our industry has worked on, we promote the IQA’s vision of educating and connecting our extractive industry.

“Most of all, it is very satisfying and rewarding to be recognised for the work we do among our peers.”

Independent quarry owner, supplier GM

Joanne Payne has been involved in the quarrying industry for the best part of three decades and is the general manager of Sequel/Impact Drill & Blast.

Joanne Payne, the general manager of Sequel Drill & Blast and owner of Braeside Quarries.
Joanne Payne, the general manager of Sequel Drill & Blast and owner of Braeside Quarries.

She is a vice president on the board of the IQA and is also a member of Cement Concrete Aggregate Australia’s (CCAA) Queensland branch committee.

On the CCAA committee, Joanne is the only representative who is an independent quarry owner. Joanne and her family own Braeside Quarries, whose site is between Stanthorpe and Warwick, in southern Queensland.

Sequel Drill & Blast has more than 30 years’ combined experience in large open cut mining to small scale blasting in sensitive areas, and has predominantly operated in Queensland and northern New South Wales.

In 2014 the company acquired Impact Drill & Blast from industrial and safety giant Jeminex, and it now operates across NSW, the ACT, Queensland, South Australia and Victoria.

Sequel Drill & Blast has maintained the Sequel banner for its NSW, ACT and Queensland operations, and operates as Impact Drill & Blast in Victoria and South Australia.

Sequel offers full rock on ground services, including full blast management plans, blast design expertise, drilling, explosives, shotfiring, laser profiling and boretracking, and monitoring of air blast and ground vibration.

It has collaborated with a variety of blue-chip companies in the extractive industry, including Boral, Hanson, Holcim, Sibelco and Brisbane City Council, and provided its drill and blast services to a broad range of civil construction projects, including Brisbane’s Legacy Way tunnel, the Victorian Regional Rail Link, Adelaide’s Southern Expressway duplication and NSW’s Hunter Expressway, plus upgrades to sections of the Pacific Highway.

As previously reported in Quarry (Vol 23, No 3, March 2015), Sequel also provided drill and blast services to the Wagner Group’s Brisbane West Wellcamp Airport, Australia’s first privately funded aerodrome near Toowoomba.

On this project the group drilled more than eight million tonnes of basalt in two years and, armed with 108 tonnes of explosives, blasted more than 40 shots, the largest of which yielded 448,000 tonnes of basalt (considered to be at least the largest quarry blast in Australia, if not the world).

The blasted aggregate was subsequently used in the formation of the airport’s 2.7km long runway.

Sequel/Impact is also a keynote sponsor of the IQA’s North Queensland and South Australian branches and has also sponsored IQA activities throughout the country.

To find out more about the IQA Awards, including the Gold Environment Award, visit

Applications and nominations close on 31 July, 2018.

References & further reading

1 Explosive potential for tyre crumb. Waste Management Review; 12 December, 2016.

Thursday, 24 January, 2019 07:51am
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