DRA Global – December 2019

DELIVERING SUSTAINABLE OPTIMISATION

T KSS Multi-Sensor Systems

n Energy Costs and ve Process Efficiencies

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DRA GLOBAL: HELPING MINING COMPANIES REALISE THE BIG PICTURE FOR THEIR PROJECTS

DECEMBER 2019

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DRA GLOBAL

DRA GLOBAL IS DELIVERING INNOVATION TO THE MINING SITE, TURNING UNDERPERFORMING PROJECTS INTO OUTSTANDING ONES

D

RA Global (DRA) is a diversified global engineering, project delivery and operations management group. Founded

in 1984, its impressive track record spans over three decades. With expertise in the areas of 04

project development, mining, mineral processing, plant optimisation, operations & maintenance and related water, energy, and infrastructure requirements, the company successfully delivers comprehensive solutions to the resources sector.

DRA has detailed design and construction at its core but also supports major innovations to drive cost savings at the PEA (Predicted Energy Assessment) level while focused on guiding these projects through to construction.

Brent Hilscher, DRA’s Director of Process for Western Canada, was brought in to broaden the company’s global footprint and start its Vancouver office. Expanding DRA’s impressive array of services, Hilscher brings expertise in ore sorting, floatation, grinding and extraction. “Typically, when you look at a block model, there won’t be huge DECEMBER 2019

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DRA GLOBAL

C O M PA N Y FACT S

• 4,300 staff worldwide • 4,500+ projects completed globally • 3 decades of experience

variability in the grade of the deposit and every block looks like it’s 100% ore,” he explains. “But, when you take that block and you crush it, you normally find that half of the rocks that leave your gyratory are waste rocks. Extraction is a resource and cost intensive process, so, there’s a lot of potential to take that crushed material and reject a certain amount, allowing us to boost mill feed grade while using less power and water.”

DRA employs many distinct technologies for bulk and particle sorting.

For bulk sorting prompt gamma neutron

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activation analysis (PGNAA) is one of the most common, where the ore is scanned and exposed to neutrons.

Gamma rays are re-admitted from the

“ EVERY ROCK IS SCANNED INDIVIDUALLY WITH TECHNOLOGY CAPABLE OF ANALYSING EACH PARTICLE TO TELL YOU WHAT’S ORE AND WHAT’S WASTE” — Brent Hilscher, Director of Process, Western Canada, DRA Global

DECEMBER 2019

ore with specific signatures a result of the atoms contacted which can, for example, reveal how much copper is in the ore on the conveyor. “Particle sorting is where I probably spend most of my time,” adds Hilscher. “Every rock is scanned individually with technology capable of analysing each particle to tell you what’s ore and what’s waste.”

During this process, a variety of sensor methods are used to improve efficiency. “Dual energy

CLICK TO WATCH : ‘DRA GLOBAL OVERVIEW’ 07 x-ray transmission (XRT) looks at

gold ore, it could be that the estimated

the density of particles and does so

gold value is determined based on iron,

by compensating for the size of the

titanium, and zirconium, things you

rock using two energy levels of x-ray,”

might not often think of being associated

explains Hilscher. “The technology has

with gold,” adds Hilscher. “It could

advanced to the point where we can

also be that the waste has a certain

look at the density profile of a block

quantity of things that the ore does not,

rather than the average density of the

so you could create reverse correla-

rock and use that characteristic profile

tions with the XRF.” Other techniques

to tell the difference between ore and

include the use of lasers which assess

waste.” DRA also deploys XRF, which

the brightness of the rock and its

provides a profile of the heavier ele-

translucent characteristics. However,

ments and can detect copper, lead,

not all approaches are fruitful. Hilscher

zinc, titanium, zirconium and more to

has worked on more than 40 major

help determine the ore’s value. “If it’s a

projects, where his team have had little c a na da .busi ne ssc h ief. com

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DRA GLOBAL

CLICK TO WATCH : ‘BRENT HILSCHER FOR DRA GLOBAL’

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success with electromagnetic sensors,

metric for operations where, for example,

and admits that “you want to keep an

we’ll look at how much gold or copper

open mind but some techniques work

is recovered at the end of the process.

better for certain ore types, so it’s

When we do ore sorting, we’ll often

important to match the right analysis

throw away 5% or more of the valuable

approach to the specific site”.

minerals, so we developed a metric to

Allied to the practical dynamics of

learn the actual value of what’s being

the sorting process, Hilscher believes

lost where the operating costs for

ore sorting economics are crucial.

the extraction and tailings facilities

“Building an economic model for every

are incorporated into that recovery

project tells us what the optimum

number. Discarding a low-grade rock

operating conditions are going to be.

would have a positive impact on profit

A key metric is profit recovery.

recovery, which rewards us for throwing

Normally, metal recovery is a driving

away rocks we’re losing money on.”

DECEMBER 2019

Preparing an economic model for

payback period for a specific project.

each project helps DRA build the best

“For Brownfield projects we’re usually

algorithm to support the second phase

targeting a payback of six months,”

of testing with a bulk sample. “The eco-

says Hilscher. “That seems to be what

nomic model is able to show us the best

mining companies are looking for

sorter operating conditions,” confirms

these days and it’s certainly achievable

Hilscher. “We can see the best upgrade

for a lot of these ore sorting projects. For

ratio for the ore sorter to be running at,

Greenfield, it’s even easier because

so that once we get into the large-scale

your CAPEX is so much lower. For

test, we’ve got the correct algorithm

example, for a single sorter Brownfield

and operating setpoints for the deposit.”

system, it might cost $5mn to install a

That test work and algorithm sup-

200 tonne per hour system, but with

ports the economic model, allowing

the ore sorting equipment incorporated

DRA to more accurately define a

into your design at the beginning of

E XE CU T I VE PRO FI LE

Brent Hilscher Brent Hilscher has 20 years’ experience in mining and mineral processing. He has operated and supervised mineral processing plants, published papers, patented technologies, and been a speaker at over a dozen conferences and universities in Canada and around the world. Brent has led design and construction projects for Teck, Goldcorp, New Gold, Barrick, Xstrata, Agnico Eagle, and many others. He won the CMP Bill Moore Award for technical excellence in 2013, and served as an officer in the Canadian Armed Forces.

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technology combinations, including: X-ray transmission (XRT); X-ray

Focusing on pre-concentration adds previously uneconomic zones to ore and mineral reserves, and improves the effectiveness of ore blending management programs. Processing low-grade stockpiles, even waste dumps, and selective upgrading generates value from previously uneconomic material. This leads to reduced tailings, less environmental impact, reduced milling energy requirements — all which add value to the life of the operation.

fluorescence (XRF); induction; optical-color and 3D laser.

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“ METALLURGISTS TEND TO BE WORRIED ABOUT RECOVERY. GEOLOGISTS ARE CONCERNED ABOUT OUNCES AND POUNDS IN THE GROUND. MINING GUYS ARE FOCUSED ON TONNES, WHILE CEOS ARE COUNTING THE DOLLARS. I’VE FOUND THAT THE ECONOMIC MODEL DOES A GREAT JOB OF BRINGING ALL THOSE PEOPLE TOGETHER AND HELPING THEM SEE THE BIG PICTURE” — Brent Hilscher, Director of Process, Western Canada, DRA Global

Hilscher worked on a silver mine 12 months from closure due to constantly declining grades. Ore sorting was investigated to get the grades back up.

“We did the test programme, we got the samples and discovered that nine out of 10 of their rocks were below cut-off grade,” explains Hilscher. “But one out of 10 of their rocks was extremely valuable. So, it was a very easy sort. We could have used XRF, XRT, laser, any one of those would have worked, so we scanned the rock with a conservative approach only throwing away 60% of the rock to begin with. We eventually achieved double the feed grade, with over 95% silver recovery.”

DRA has worked for many years to develop approaches to dense media

construction, the cost can be halved.”

separation (DMS) that use fluids of

In greenfield designs there is also an

suitable density so that the minerals

opportunity to reduce project capital

lighter than the fluid float and those

while maintaining or increasing designed

that are denser sink. Hilscher’s team

production. Hilscher notes that instead

is also developing conservation tech-

of spending $100mn on a new mill, a

nologies to meet the changing needs

smaller mill with sorters could produce

of the sector. “Ore sorting is just part

the same product for $70-80mn.

of our tool kit for project revitalisa-

“Spending a little more on your ore sort-

tion. DMS coarse particle recovery,

ing system up front can lead to a clear

modular construction and many others

win for the overall project,” he confirms.

are looked at for each new project. c a na da .busi ne ssc h ief. com

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DRA GLOBAL

Bel Air Bauxite

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In 2017 DRA Global was awarded the contract for the development of a port facility and associated infrastructure for the export of bauxite, by Alufer Mining in Guinea. The Alufer Bel Air Mine project was DRA’s first causeway development, which expanded the company’s exposure within the marine environment. Bel Air was expected to have an initial production rate of 5.5 million tonnes per annum and included a 22.5km haul road running over eight river crossings, an export facility with the ROM tip that feeds a 6500-tonne live capacity stockpile, and a causeway extending 1.4km into the Atlantic Ocean, where a barge load out berth was constructed.

DECEMBER 2019

The scope included all the necessary infrastructure to operate the facility: construction camp, wellfields, power generation, offices, laboratory, workshop and a bailey bridge across the Koundinde Work on the project commenced in January 2017 and was completed in August 2018 before commercial production was achieved within the first six months of operation. Alufer is on target to reach its annual production rate of 5.5 million wet tonnes by the end of 2019. DRA Global’s extensive material handling, earthworks and infrastructure design capabilities have contributed significantly to the success of the project.

15 Hydrofloat is a new coarse particle

so they can test solutions in their own

recovery flotation technology, which

operations.” The solutions DRA offer

we’ve started installing for clients,” he

leverage the company’s relation-

confirms. “It uses the slurry current to

ships with key tech partners including

assist in the flotation of exceptionally

Tomra, Steinert, Eriez, Scantech,

coarse particles.”

Rados, Minesense and others.

Hilscher notes that mining has his-

Safety is a hot topic in the industry

torically been hesitant to innovate but

today. Given the tragic impact of

the adoption of ore sorting technolo-

recent dam failures in Brazil, Hilscher

gies into the mainstream has proved

is particularly interested in developing

the exception because the results

DRA’s services to provide alternative

are so dramatic. “It comes down to

tailings solutions. “We’ve done a lot

education,” he says. “We need to make

of work on dry stack tailings, which is

mining professionals aware of the

becoming a more popular option for

benefits from emerging technologies,

plants,” he says. “Even within dry stack c a na da .busi ne ssc h ief. com

DRA GLOBAL

designs, there are optimisation opportunities. Instead of sending all the tailings sand to a filter plant, you may have a two-stage cyclone plant first.

The coarsest fraction is used for roads and earthworks, the fine fraction goes to the existing tailings pond (or co-disposal piles), and the mid-size material is filtered. This compromise reduces tailings pond sizes by two thirds while also removing most of the fines and clays that are so difficult to filter.

“Of course, sensor sorting, DMS, and 16

coarse particle flotation all have a tailings pond benefit because if you can take those worthless rocks and keep

“ BUILDING AN ECONOMIC MODEL FOR EVERY PROJECT TELLS US WHAT THE OPTIMUM OPERATING CONDITIONS ARE GOING TO BE” — Brent Hilscher, Director of Process, Western Canada, DRA Global

DECEMBER 2019

them coarse you are able to put them in a waste pile or road bed. That’s a direct reduction to your tailings pond size. The pond dam won’t need to be expanded as often, and that tends to make them much safer,” he adds.

Hilscher believes that in order to drive innovation, all metrics and operational concerns need to be addressed. It’s a weighty issue where he argues a balance must be struck.

“Metallurgists tend to be worried about recovery. Geologists are concerned

1984

Year founded

4,300 Number of employees

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about ounces and pounds in the

achieve all of these goals simultaneously.

ground. Mining guys are focused on

We can drive growth, while making

tonnes, while CEOs are counting the

tailings ponds smaller, use less water,

dollars,” he muses. “I’ve found that

less energy, and produce less CO2.

the economic model does a great job

All of this simply by rejecting the

of bringing all those people together

worthless rock earlier in the process.

and helping them see the big picture.

It’s the future for sustainable mining

How do the ounces, tonnes, and

and something we’re really excited

recovery feed into making a deposit

about at DRA Global.”

as economical as possible? What can we do to reduce the environmental impact and also make the mine more profitable? With ore sorting, and other preconcentration techniques, we can c a na da .busi ne ssc h ief. com

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