Categories
Mining facts

Magnetite and Magnetite Mining in Canada

Magnetite (also magnet iron, magnet iron stone, iron oxide, or iron (II, III) oxide) is the most stable iron oxide with high resistance to acids and alkalis. It has a cubic crystal system and a chemical molecular formula Fe3O4. One of the iron ions is divalent. The other two are trivalent, so Magnetite is also referred to as iron (II, III) oxide. It has a ‘Mohs’ hardness of 5.5 to 6.5, a black color, a line color, and a matte metallic sheen.

Crystal structure of magnetite: oxygen (gray), divalent iron (green), trivalent iron (blue), iron ion in octahedron gap (light blue octahedron), iron ion in tetrahedron gap (gray tetrahedron) – Wikimedia commons

History of magnetite mining

Magnetite is one of the most powerful magnetic minerals. When the temperature falls below 578°C, the magnetization is mostly aligned in the earth’s magnetic field direction. A remnant magnetic polarization of the order of magnitude 500 nT results. In this way, magnetite crystals can preserve the direction of the earth’s magnetic field at the time of their formation.

The investigation of the direction of magnetization of lava rock (basalt) led geologists to observe that in the distant past, the magnetic polarity of the earth must have reversed from time to time. Due to its excellent magnetic properties, Magnetite is still used today in the construction of compasses. As a color pigment, it bears the name iron oxide black.

The name magnet emerged from the Latin name form magnetem (from nominative magnes – magnet). The medieval mineral name Magneteisenstein and the name Magnetit were introduced by Wilhelm Haidinger in 1845.

According to Greek legend, the shepherd Magnes is said to have been the first to find a natural stone with magnetic properties. The shepherd found the stone on Mount Ida when his shoe-heel stuck to the ground.

Magnetite is magnetic!

Another possible origin of the name refers to the Greek landscape Magnesia. Georgius Agricola (1494-1555) used the term “magnetic stone” in his well-known work De Re Metallica in 1550 as an ingredient for glass production.

The reference to the stone magnes, named after a shepherd of the same name, can be found in works by the Roman writer Pliny, the Elder. Pliny distinguished two types of magnes; a “male” and a “female,” of which only the male had the power to attract iron and thus corresponded to the actual Magnetite. “Female” magnesite was probably manganese ore, similar to the “male” in appearance.

Illustration of Magnes the shepherd

The mineral might have also been named after Magnesia, a landscape in Thessaly or the city of Magnesia. It is also possible that the name Magnetite comes from other Greek or Asia Minor places of the same name, in which iron ore chunks with magnetic properties were found over 2500 years ago.

Occurrence

Magnetite occurs in solid or granular form and also as crystals. The latter are often octahedral in shape, so each has eight triangular boundary surfaces. It is a ubiquitous mineral, but it is rarely the main component of an iron rock.

Magnetite
Magnetite

Magnetite is found in numerous igneous rocks such as basalt, diabase, and gabbro in metamorphic rocks. Its hardness means that Magnetite remains intact as sand in river sediments despite weathering processes.

Most of the Canadian Magnetite comes from the Labrador Trough region, on the border between Newfoundland and Quebec and Labrador. Vast deposits of Magnetite can be found in Nunavut, Faraday Township, Hastings County, Ontario, and Outaouais, Québec, Canada. Magnetite deposits are mined in British Columbia at Mount Polley.

Magnetite Uses

Dense Media Separation

Magnetite can be used in industry as a giant magnet. This has applications for sorting valuable materials from others in order to extract value. Those that panned for gold used pans, water, and agitation to remove dirt and debris from valuable nuggets of the valuable ore. Recyclers use magnetite in huge magets to sort valuable scrap metal from less valuable material. Magnetite mining helps the world extract value in an efficient way, whether from raw material or to repurpose discarded material in a green and environmentally friendly manner.

Dense Media Separation has its origins in cleaning coal. Finer coal material is separated from impurities making the energy derived from coal mining cleaner and more efficient.

Dense Media Separation is used in recycling industries to sort scrap metal. This is useful to give valuable material new life in everyday products from smartphones to electric vehicles. Magnetite makes recycling much more efficient, reducing the market price for recycled metals, allowing it to compete with newly mined metals in manufacturing.

Scrap metal recycling

Potash mining is a significant industry in Canada, particularly in the province of Saskatchewan. Potash is primarily used in fertilizer to more cheaply and efficiently feed a hungry world. Magetite, through the process of dense media separation, is used to purify extracted potash. Potash is a mixture of potassium chloride (KCl) and sodium chloride (NaCl). Magnetite is used in dense media separation in the potash extraction to remove NaCl from solution, leaving the valuable KCl behind.

Potash mining

Electrical industry

Along with hematite, Magnetite is one of the essential iron ore. At 72 %, iron has the highest content of this metal. The term iron oxide black means finely ground Magnetite.

Magnetite plays an essential role in the electrical industry. The occurrence of magnetic ores in rocks such as Magnetite or ulvite enables geological studies to be carried out on the earth’s magnetic field orientation.

Due to the 100 % spin polarization of the charge carriers predicted by theory, Magnetite is also traded as a hot candidate for spin valves in spin electronics.

As a building material

Magnetite is used in the construction industry as a naturally granular aggregate with a high bulk density (4.65 to 4.80 kg/dm 3 ) for heavy concrete and structural radiation protection. Thanks to the heavy mineral, the building material can help to attain a solid concrete density of more than 3.2 t/m3; and is helpful in the construction of hospital radiology units. 

Radiation protection concrete achieves a shielding function through its mass, but an aggregate with radiation-absorbing properties such as Magnetite increases the protective effect. 

Magnetite in jewelry

Classic jewelry clasps are often extremely filigree and, therefore, difficult to close. Magnetic jewelry clasps provide a remedy; they enable necklaces and bracelets to be easily closed. The strong magnets ensure a firm hold. To open the chain or strap, wearers simply have to slide two locking parts sideways.

Wearing jewelry is helped by magentic clasps

Heat storage

Industries use natural iron oxide minerals because they can keep the heat very efficiently. They use Magnetite in heat blocks in night storage heaters. Magnetite facilitates more extensive storage of thermal heat much more sustainably compared to other materials.

Magnetite is used in foundry metal protection

The mineral helps to prevent surface defects in metal fixtures in foundries. Natural mineral magnetite where it crashed into a pure, dry, and fine powder that’s used to protected casted metals.

Magnetic therapeutic beliefs in ancient times

Magnetism has been used traditional therapies for thousands of years, though modern science disputes therapeutic effect in placebo trials. The Greeks used magnetism in ancient treatments in 5th century BC. In China, magnets have been integrated into traditional therapy for over 2000 years, magnetism was also in traditional therapeutics in India and ancient Egypt to heal broken bones and other ailments.

Hippocrates described their healing power in the same way as the legendary doctor Paracelsus, who recommended treatments with magnets. Even during this time, women and men wore jewelry made from magnetic ores.

In ancient times magnetite mining became a major economic activity in the Thessalian city of Magnesia. Today, like the ancient Greeks, Canada has a reputation as a leading mining nation with the minerals sector as a core part of the economy. Magnetite mining supports jobs and increases economic growth in provinces and territories where it is mined along with broader benefits to Canada’s national economic output.

Categories
Remediation

September site tour with the Habitat Remediation Working Group

The remediation of Hazeltine Creek has been planned and advanced through the direct collaboration of Mount Polley mine employees, government agencies, First Nations and their technical advisors. This collective is called the Habitat Remediation Working Group (HRWG).

Recently, members of Mount Polley mine, Golder Associates Ltd, FLNRO (Ministry of Forests, Lands, Natural Resource Operations and Rural Development) and the Xatśūll First Nation attended a September 2020 HRWG tour.

On the tour the HRWG inspected the construction of habitat features in Lower Hazeltine Creek. The group also inspected the weir and fish ladder at Polley Lake, the functioning spawning habitat in Upper Hazeltine Creek and the terrestrial plant growth in Polley Flats.

The group viewed all stages of remediation, from installation of habitat features to a remediated ecosystem in Upper Hazeltine Creek that is maturing into a self-sustaining landscape used by all manners of life forms.

Discussions on the tour included:
• Local nursery plant sources;
• Local contractors support in the remediation efforts;
• Reflections on how far the remediation has advanced;
• Reopening plans for the mine;
• Plans for the continued use of the weir on Polley Lake for flood control and fish rearing in Hazeltine Creek until the plants in the terrestrial flood plain mature; and
• In stream habitat features installed are potentially superior to those that existed pre-2014.

Below are some photos from the tour (September 2020).

Hazeltine Creek Reach One and revegetated riparian areas looking upstream toward Polley Lake.
Hazeltine Creek Reach One and revegetated riparian areas looking upstream toward Polley Lake.
James Ogilvie, Senior Water Resources Engineer at Golder Associates, describes functionality of reconstructed portions of Hazeltine Creek Reach One
Golder Associates Water Resources Engineer explains functionality of reconstructed portions of Hazeltine Creek Reach One
Hazeltine Creek Reach One and revegetated riparian areas looking downstream
Hazeltine Creek Reach One and revegetated riparian areas looking downstream
Categories
Remediation

Remediation continues at Mount Polley Mine site

Please check out this write-up by the Soda Creek First Nations on the remediation work being done at Mount Polley and the tour completed by South Creek Indian Band (SCIB).

Remediation continues at Mt Polley Mine site (PDF)

Categories
Remediation

Experts recommend leaving tailings in Quesnel Lake

Lately we have received questions about the water quality at Quesnel Lake, so here are a few Q&A’s which address this subject.

First, what it means to conduct remediation?

According to the BC Environmental Management Act, “remediation” means action to eliminate, limit, correct, counteract, mitigate or remove any contaminant or the adverse effects on the environment or human health of any contaminant.

At Mount Polley, using the results of the detailed site investigations, and the human health and ecological risk assessments, the goal of the mine’s environmental remediation work is to repair and rehabilitate the areas impacted by the tailings spill such that they are on a path to self-sustaining ecological processes that result in productive and connected habitats for aquatic and terrestrial species.

As the impacts of the spill were determined to be primarily physical and not chemical, this has meant that the focus of the work has been on repairing and rebuilding habitats. 

Where can I find data about the water quality in Quesnel Lake?

The BC government website hosts an interactive map of surface water monitoring sites in the Province which gives access to results of water sampling and analyses, including Quesnel Lake and other surface water sites around the area of the mine. 

Why was the decision made to leave the tailings at the bottom of Quesnel Lake?

Research and monitoring of the physical and chemical stability of the tailings on the bottom of Quesnel Lake indicate that they are not causing pollution and studies of the bottom-dwelling (benthic) organisms have shown that they are slowly recolonizing the lake bottom as native sediment slowly deposits on top of the organic-poor tailings, bringing organic matter to the lake floor. 

After completing a Net Environmental Benefit (NEB) assessment, experts recommended that the best approach for remediation of the tailings in Quesnel Lake was to leave them alone and cause no further disturbance.

The experts determined that any attempt to remove the tailings could significantly disrupt the present ecosystem and set back the progress that had already occurred.

Remediation at Mount Polley is all about creating the conditions for successful natural recovery, and not doing more damage.

Categories
Mining facts

Mining and Mineral Processing at the Mount Polley mine

In the Mount Polley Mine, run-of-mine ore from the open pits and underground is hauled to the crusher.  The crusher has three stages of crushing involving five crushers, twenty conveyors and four sets of screens.  Ore is dumped by the surface mining fleet into the feed pocket of the primary gyratory crusher, and is then crushed in three stages to produce a product at finer than 16 mm for the grinding circuit. Periodically, the crusher also used for the production of aggregates used in tailings construction and other tasks.

The grinding circuit consists of two parallel rod mill/ball mill circuits and a pebble mill circuit. Crusher product is first split between two rod mills where water is added to form slurries.  The rod mill discharge is pumped to the primary hydrocyclones that classify the particles by size.  The larger particles flow to feed the ball mills while the fine particles report to two flash flotation cells. The ball mills are in “closed circuit”, meaning that the discharge is pumped to the classifying units (primary hydrocyclones) and the particles will not pass to the next grinding stage until they are fine enough to feed through the flash flotation cells.  The underflow from the flash flotation cells is pumped to the secondary hydrocyclones, the flash flotation product can report directly to the concentrate circuit or to regrind for further upgrading.

The coarse particles classified by the secondary hydrocyclones reports to three pebble mills for further size reduction. The pebble mills are in “closed circuit” with the secondary hydrocyclones and product that is sized at 65% finer than 200-mesh is fed to the flotation circuit. Pebbles obtained from the triple deck screen in the crusher are used as grinding media in the pebble mills.

The flotation circuit separates the valuable minerals from the rest of the crushed rocks. With the addition of reagents, the valuable minerals, mostly in the form of sulphide minerals chalcopyrite and bornite, are separated by flotation and are collected and upgraded to produce a concentrate. Initial separation is completed in a rougher/scavenger circuit, where the remaining minerals are discarded as tailings (which flow by gravity to the Tailings Storage Facility).  Rougher concentrate is reground in a regrind mill and further upgraded in a cleaner circuit to produce the final concentrate product. Cleaner tailings are recycled to the scavenger circuit.

The concentrate from the flotation circuit is dewatered in two stages: the thickener settles particles and decants water so that the settled particles form a sludge by sedimentation and have a reduced water content of roughly 25%-30%; pressure filtration further reduces water content to approximately 8%. The water removed is utilized as process water. The filtered concentrate is stored in the load-out building and loaded onto 40-tonne trucks for shipping. Tailings materials generated by mill operations are piped via gravity to the TSF.

Categories
Community Mining facts

Who works at Mount Polley?

At Mount Polley, we look for individuals to join our workforce who display a variety of skills and training levels.

We have a training department that will train workers from other industries.

Our key goal is to source workers locally. The furthest away workers are usually recruited from is Quesnel or Williams Lake. Several of Mount Polley’s staff are from Big Lake, Horsefly, and Likely, and live near the mine.

Staffing Numbers at Mount Polley

When Mount Polley is in full operation, we have as many as 370 staff working on rotation at the mine, most often in four crews.

Shifts are typically a 12-hour day shift and 12-hour night shift; four crews; seven days on, seven days off.

Additionally, we have about 50 support staff including administrators, supervisors, warehouse workers, engineers, geologists, assayers, technical personnel, and human resource staff.

Mount Polley mine
Mount Polley mine – Creative Commons license CC0
Categories
Mining facts

Likely Area Mining History

The area around Likely has a long and fascinating history of placer mining. Placer mining refers to mining materials (mostly gold) deposited in ancient stream beds that are still largely unconsolidated (i.e. relatively loose materials).

Some of the earliest gold discoveries in the area were made in 1859, one in the Horsefly River, and one in the Dancing Bill Gulch. The latter became known as the China Pit and then the Bullion Pit, and is located just downstream of Likely on the west side of the Quesnel River. The Bullion Pit is now a local historic site with a public walking trail.

Quesnel Forks information sign at the entrance to the historic townsite

Placer gold was also discovered near the mouth of Keithley Creek on the Cariboo River about 12 km upstream from Quesnel Forks in July 1860. Other significant discoveries were subsequently made just 4 km south of Likely on Cedar Creek, and in Quesnel River itself.

In 1897, the Golden River Canal Co. decided to build a dam across the Quesnel River at the outlet from Quesnel Lake in order to block the river and be able to work the gravels from the bottom of the river. The tent town that developed on the site was known as ‘Quesnel Dam’. In 1920, the dam was dynamited and the remnants of the dam can be seen just north of the Likely Bridge in Likely. After the removal of the dam, the residents decided to rename the town ‘Likely’ after a local prospector, John Likely.

Drone image of the Bullion Pit near Likely, BC

The Bullion Pit ulimately became a very significant gold producer in the area. BC Minfile report number 093A 025 states that “In 1897, the Consolidated Hydraulic Mining Company commenced full scale operations and between 1898 and 1902, the company processed 5,912,700 cubic metres of mixed materials, recovering 1,402,316 grams of gold at a recoverable grade of 0.132 grams per tonne gold… Estimations indicate that a total of 200 million tonnes of material were removed by hydraulic methods and 5.463 million grams (175,644 ounces) of gold were produced.” Indications are that much of this material was discharged directly into the Quesnel River.

Polley Lake Outlet Structure: water works for placer mining — early 1900s. Courtesy of BC Archives.

The shortage of water in the early 1900s led the operators of the Bullion Pit to construct a number of water control and diversion works on local streams and lakes to gather water for the hydraulic operations at the pit. Photos from the BC archives, including ones featured in the TV program “Gold Trails and Ghost Towns – The Bullion Pit episode”, document weirs and diversion ditches built on Polley Lake and Hazeltine Creek and other creeks in the area.

To learn more about Likely’s mining history, visit the Cedar City Museum and Info Center located in the Cedar Point Provincial Park in Likely, BC.

This Facebook page gives regular updates on the areas in BC that were part of the mine’s early gold mining history.

Historic building in Quesnel Forks

Many placer mines continue to operate in the area around Likely, including near Quesnel Forks. Quesnel Forks is a restored ghost town located 12 km outside of Likely with a rich mining history and is also worth a visit. It is situated at the point where Cariboo River meets the Quesnel River, and features a beautiful campground and a number of restored and partially restored old buildings.

Historic building in Quesnel Forks. Courtesy of Mount Polley
Historic building in Quesnel Forks overlooking Quesnel River. Part of the history of the Mount Polley site and surrounding area.
View of Quesnel River at confluence with Cariboo River from Quesnel Forks historic townsite
View of Quensel River from Quesnel Forks historic townsite.
Cedar City Museum and information centre in Cedar Point Provincial Park in Likely, BC on Quesnel Lake.
Historic mining equipment on display in Cedar Point Provincial Park in Likely, BC
Categories
Community

Mount Polley is doing its part during COVID-19

We hope that you and your family are staying safe and following the preventative measures and actions you can take to stay healthy and prevent the spread of COVID-19.

We are doing our part during COVID-19. Imperial Metals Mount Polley mine has donated two boxes of N95 masks and four boxes of surgical gloves to the Williams Lake Hospital.

Newcrest-Imperial Metals Red Chris mine is providing additional medical support in Iskut, Dease Lake and Telegraph Creek, and is working with the Tahltan Nation to support the provision of basic groceries to the Iskut, Dease Lake and Telegraph Creek communities. In addition, Newcrest will help source health and sanitary supplies pending availability and lead times.

Review how you can prevent the spread of COVID-19 in your community.

Categories
Mining facts

Is Mount Polley Dumping Waste into Quesnel Lake?

There has been recent speculation about whether or not Mount Polley is dumping waste into Quesnel Lake. In short, the answer is no. Current treatment of water at Mount Polley, including the dilution zone at depth in Quesnel Lake, ensures water released into Quesnel Lake is in line with BC and Canadian water quality standards. Mount Polley discharges only treated mine site water that meets strict Environmental Management Act (EMA) permit guidelines.

All mine site water is collected and is treated by a Veolia ACTIFLO™ water treatment plant before it is released into Quesnel Lake. (see veoliawatertech.com for more information on their treatment systems and how they work.) The water going into the WTP (influent) is monitored on an ongoing basis (measurements of turbidity every 15 seconds) and the treated water leaving the plant (effluent) is sampled regularly for analysis. The lake water quality is also routinely monitored and sampled regularly as part of the mine’s Comprehensive Environmental Monitoring Plan.

The following are facts that explore, in more detail, the discharge from Mount Polley into Quesnel Lake. We hope this information provides factual clarity about Mount Polley’s approved activities.

Is Mount Polley’s discharge having negative effects on Quesnel Lake?

There are no indications in the monitoring data that the Mount Polley discharge is having any negative effects on Quesnel Lake water quality. If you are interested in looking at some of the water quality data that has been collected on surface water in the area around the Mount Polley Mine, the results are available through the BC Government Surface Water Monitoring Sites Interactive Map

Is the water in Quesnel Lake contaminated? Is it safe to drink?

At this time, there are no indications of contamination of Quesnel Lake water from the Mount Polley spill. The mine, and the Ministry of Environment and Environment Canada, continue to monitor Quesnel Lake. With the exception of natural causes, the lake does not exceed environmental guidelines for any of the constituents of concern that are found in the Mount Polley tailings.

As early as August 12, 2014, BC’s Interior Health Authority (IHA) rescinded all water use restrictions from Quesnel Lake (including for “drinking water, personal use, fishing, swimming and recreational purposes”), except for the immediate impact zone where Hazeltine Creek entered Quesnel Lake. The IHA notice also stated that “Interior Health has no reason to believe that this water was ever exposed to unsafe levels of contaminants from the mine breach. As a result, flushing and testing of individual water supply systems is not considered necessary.”

All water use restrictions were fully rescinded July 13, 2015. (Note: IHA always advises that surface water be treated for pathogens prior to use/consumption.)

How much is the mine discharging into Quesnel Lake?

The Environmental Management Act permit annual average authorized discharge rate is 29,000 cubic meters per day. The actual discharge rate depends upon the rainfall experienced at site which varies from year to year. In 2019, the annual average discharge rate has been 14,883 cubic meters per day, significantly less than the mine’s permit allows.

Categories
Community Remediation

Staying connected to the community during Mount Polley’s remediation

Did you know that over the past six years, over 39 community meetings have been organized and hosted by Mount Polley management and environmental staff?

Mount Polley is committed to the environment and to ensuring the community is kept up to date on remediation efforts.

Over 24 meetings have been held in Likely, the community in closest proximity to the Mount Polley mine. Meetings have also been held in the communities of Quesnel, Horsefly, Big Lake and Williams Lake.

These meetings provide an opportunity for local residents to learn about the activities and progress of the remediation work and research programs being conducted, and the opportunity to engage and ask questions.

There is still work being done to complete the rebuilding of fish habitat in Hazeltine Creek. The rebuilding and revegetating of the lower part of the creek will be the last part of the remediation work to be done.

Guest speakers have included consultants and representatives from provincial Ministries who help educate the local community about environmental remediation.

Furthermore Mount Polley has established The Mount Polley Mine Public Liaison Committee (PLC).The PLC is comprised of representatives from the local communities of Likely, Big Lake, Horsefly and Williams Lake, local First Nations, government ministries, consultants and mine staff.

Meetings are held on a quarterly basis, with the purpose to share information about activities at the mine site with the PLC members, who are there as representatives of their communities. The agenda for each meeting includes updates on mine operations, environmental monitoring, and remediation. There is also a roundtable discussion at each meeting for all participants to pose questions and discuss any community concerns.