User:Kedmvl/Creighton Mine

Creighton Mine is an underground nickel, copper, and PGE mine. It is presently owned and operated by Vale Limited (formerly known as INCO) in the city of Greater Sudbury, Ontario, Canada. Mining began in 1901, and it is currently the deepest nickel mine in Canada.

The Mine: Discovery and Development
The deposits at Creighton mine were the first mineralized deposits discovered in the Sudbury Igneous Complex (SIC) mining camp. They were discovered by A.P. Salter in 1856 due to deflections in his compass readings. Production at Creighton Mine began in 1901 under the Canadian Copper Company, and later the International Nickel Company (INCO). The mine was an open-pit mine from 1901 to 1908, and was transitioned to an underground mine in 1906. In 1969, the 7138-foot No. 9 shaft was completed, making it the deepest continuous mine shaft in the Western Hemisphere. Brazil's Vale announced a $19.4 billion takeover of INCO, which was approved in 2007. The company was known as Vale S.A. (Vale) from 2009 onwards.

The Creighton Settlement
Creighton Mine employed 94 men in 1902, and built accommodations for the men and their families. In 1903, school classes and religious services were being held in one of the company cabins for the miner's families. As the workforce at the mine increased, the company constructed more single family homes with running water and electricity. As development continued, the company began to include rent, hydro, and employees club deductions on the company pay cheques.

In 1986, INCO announced that the company would be "getting out of the landlord business" due to the expense of maintaining the settlement to modern standards. The community of Creighton was closed on June 30th, 1988.

Formation of the Sudbury Igneous Complex
The Sudbury Igneous Complex (SIC) is an impact melt structure, formed by the collision of a meteor 1.85 billion years ago. The bolide impact created a crater 200 to 250 km across and melted the pre-existing rock, which partially filled in the crater. Today, the SIC is approximately 3 km thick, and has an elliptical footprint of approximately 60 km by 27 km.

An important geological unit within the SIC is the Sudbury Breccia, which is an impactite interpreted to have been formed during the impact. Copper, nickel, and PGE rich sulfides settled to the base of the molten Sudbury Breccia, and formed veins and stockworks of mineralization in the footwall (the non-igneous rocks underlying the SIC).

Geology of the Creighton Mine
The Creighton Mine property is home to the South Range geologic unit, which contains the main orebody of the mine. The major mineralization occurs as sulfide-rich intrusions within the footwall. The amphibole within the ore body shifts from ferro-hornblende to ferro-tschermakite amphibole. This, along with the calcium and tantalum variations and an age of titanite of 1616 billion years, has been interpreted to reflect an "increasing temperature-pressure gradient towards shear zones that were active during the Mazatzalian orogeny". It is also believed that the sulfides of this deposit were re-mobilized during this event.

A study on the formation of the ore body at the Creighton Mine indicates that the economic minerals crystalized from the sulfide melt early on in the cooling process. These minerals collected in embayments and in troughs at the base of the SIC along the footwall rock, forming "small pendants of ore" in the footwall rock. This type of mineralization is called contact type mineralization, as it occurs between the contact of the SIC and the underlying footwall. Sulfide mineralization on the property occurs as massive to disseminated sulfides, occurring as massive sulfides near the footwall and grading towards disseminated sulfides towards the hanging wall.

Ore Minerals
Common ore minerals found at the Creighton mine include chalcopyrite, cubanite, galena, ilmenite, magnetite, pentlandite, pyrite, and pyrrhotite. Less common and non-ore minerals which occur at the mine include altaite, argentopentlandite, arsenopyrite, biotite, bornite, cassiterite, cobaltite, epidote, froodite, gersdorffite, gold, heazlewoodite, hessite, hollingworthite, insizwaite, irarsite, kotulskite, marcasite, maslovite, melonite, merenskyite, michenerite, millerite, moncheite, muscovite, nickeline, parkerite, quartz, rutile, silver, sperrylite, sphalerite, stützite, tin, and tsumoite.

Production
Creighton Mine is primarily a nickel, copper, and PGE mine, but also produces gold, silver, cobalt, selenium, and tellurium.

Mining Methods
Since the first production of Creighton Mine in 1901, over 155 million tones of ore have been extracted. The mine was an open-pit mine from 1901 to 1908, and was transitioned to an underground mine in 1906. Currently, the mining methods used are bulk mining with the vertical retreat method (95% of production), and selective stoping with the mechanized cut-and-fill method (5% of ore production).

Production Levels
In 2005 the mine produced an average of 3,755 tons of ore per day on a 6 days per week schedule. In 2007, Creighton produced 793 000 tones of ore with grades of 1.62% copper and 2.8% nickel. In 2019, 6 130 000 tones of ore was produced at the Creighton mine, with copper grades of 2.67% and nickel grades of 2.68%. Ore is processed off site at Vale's Clarabelle Mill for nickel and copper, and the platinum group element (PGE) intermediates are sent to Vale's processing facility in Port Colborne, Ontario.

Seismic Events
The deep nature of the mining and mineral exploration of the Creighton mine means that some local faults are re-mobilized during normal mining operations. This re-mobilization has resulted in several earthquakes felt in nearby Sudbury and the surrounding areas. These seismic events are generally between 1.0 and 4.0 Mn, and result in temporarily halting work at the mine.

Ground Control
The ground control program at Creighton Mine costs $20 million a year, and consists of a team of over 20 people and an expansive network of smart cables and seismometers.

SNOLAB
Creighton Mine's 6800 ft level is home to the world's deepest cleanest underground physics laboratory. Originally excavated for the Sudbury Neutrino Observatory (SNO), it has been expanded into a general-purpose facility called SNOLAB. The original laboratory, the SNO, was a heavy-water neutrino "Cherenkov detector". In 2004, a $7.5 million 3-story lab was constructed for the SNO on the grounds of the Creighton Mine, creating the foundation for the laboratories known today as SNOLAB. SNOLAB was initially constructed with $70 million in capital funds, and in 2020 received an additional $40.9 million in funding from Canada's Minister of Innovation.

The Creighton Deepening Project
In 2005, two projects were underway to allow deeper mining at Creighton Mine. The first was an $8-million, four-year diamond drill exploration program that will allow for ore tonnage to be defined down to the 10000 ft level. The second was a $48-million expansion project that established production ore at the 7810 ft level and was estimated to bring 1.8 million tons of high-grade ore into production from 2006–2011. This expansion was carried out by SCR Mining and Tunneling.

In 2007, Vale announced the exploration drilling increased the proven and probable reserves at the Creighton mine to 32 million tons of 2.2% nickel and 2 to 2.3% copper grading, up from the previously defined 17 million tons of 3.2% nickel and 2.5% copper grading. This exploration also led to the discovery of high grade PGE ore at the 2150 and 3200 meter mine levels.

In 2013, Phase 3 of the Creighton Mine Deep project was underway. This expansion project will cost $247 million, will increase the mine's depth to 8020 feet, and is estimated to increase the mine's lifespan to at least 2027.

Diesel to Electric
In 2018, Vale announced they are transitioning their deep zone fleet of vehicles from diesel to electric. This is an ongoing project, as old equipment is replaced with electric equipment once it has reached the end of it's life. This move towards electric vehicles not only reduces the environmental impact of the mine, but also allows for a reduction in heat generation and diesel contamination by these vehicles at depth.

Groundwater Treatment
Groundwater naturally flows through the tailings area of the Creighton mine, posing an environmental contamination risk. To protect against contamination, groundwater from the tailings area is pumped to and treated at water treatment plants. Once treated, the water is discharged into the local watershed.

Underground Greenhouse
The 4800 foot level of Creighton Mine is a fully automated greenhouse. This greenhouse grows approximately 100 000 jack and red pine trees, which will be used in regreening and remediation of the Sudbury basin.