UtahRails.net

(This page printed from UtahRails.net, Copyright 2000-2021 Don Strack)

Kennecott's North Ore Shoot

Index For This Page

This page last updated on June 27, 2021.

(Return to Bingham Index Page)

Overview

(This research is mainly to document the purpose of the three headframes visible in photos at Bingham: the Anaconda exhaust shaft of 1975-1982; the first North Ore Shoot shaft of 1978-1993; and the later North Ore Shoot shaft of 2007 to today.)

In September 2011 Kennecott announced in a press release that work was to resume in the development of the North Ore Shoot gold and copper skarn, the underground expansion project for Kennecott Utah Copper's Bingham mine. The ore body is about 1000 feet below the current bottom of the Bingham open pit mine, and the North Rim Skarn project would involve the construction of an underground mining facilities, including new vertical shafts and horizontal drifts and galleries and declines, as well as refurbishing an existing shaft. Most of the work would be contracted out.

(A "skarn" is the area between host waste rock and mineralized ore rock, and can usually be mined due to high concentrations of minerals. At Bingham, the skarn being developed was about 2-1/2 to five times as rich as the ore currently being extracted by open-pit methods. But the high cost of underground mining made development and extraction unprofitable.)

In an oral history interview in 1993 Frank Joklik, Kennecott CEO, recalled the following.

I should also mention the North Ore Shoot. This is high-grade copper and gold mineralization in limestone formations that partly surround the Bingham Canyon monzonite stock, at a depth of 3,000 feet. It's the downdip extension of the Carr Fork mineralization we talked about previously, that Anaconda tried to mine. But the grade of the North Ore Shoot is about three times what it is in the former Anaconda land holding. In the early 1980s, we sank a shaft 3,000 feet deep and did some bulk sampling for metallurgical purposes, and also some test mining. This is a large resource, whose economics look good when copper and gold prices are high and marginal when they're low. It would be a new commitment to undertake underground copper mining at Bingham Canyon, and that decision has yet to be made.

Exploration for the North Ore Shoot in 1980-1981 was in response to the adjacent development work being done by Anaconda as part of its Carr Fork Project. The North Ore Shoot exploration began with a headframe and vertical shaft located adjacent to the main highway in Bingham canyon in the middle of the old Bingham town site, on the south side and a bit down-canyon from the new 6190 rail yard which had been completed in 1978. The headframe for the exploration and development work is visible in a photo taken in June 1981.

The North Ore Shoot was part of the development of the ore body under what was earlier known as Carr Fork. The ore bodies were part of what was known as Bingham Canyon's deep copper-gold skarn along its northern boundaries. Anaconda had discovered the skarn ore body in 1969 and began development in late 1974, with production starting from the new mine in 1979.

Kennecott held claims to adjacent ore bodies and began drilling its own exploration holes. Kennecott's own underground development began in the late 1970s with what it called its "North Ore Shoot Extension." The new headframe was in place by August 1978.

Kennecott's exploration continued as Anaconda developed what it called its Carr Fork Project. The Anaconda project shut down in 1982 due to Anaconda's financial difficulties with its world-wide operations. In late 1984 Kennecott and Anaconda announced a joint venture to develop the skarn ore body, and in late 1985, Kennecott purchased all of Anaconda's interest in its mines and claims in the Bingham district.

(View a brief timeline of Anaconda's Carr Fork Project, below)

The vertical shaft accessing the North Ore Shoot was abandoned in the mid 1980s and sealed at its top. After the shaft was sealed, the site was used as part of the overall waste rock dumping grounds.

In 2007-2008 Kennecott contracted to have recover the vertical shaft, connecting a new top-of-shaft collar with the existing vertical exploration shaft from the 1980-1981 period. The newer headframe and hoist were in the same location as the previous headframe and hoist that had been removed to allow nearby waste-rock dumps to be expanded. The headframe was re-installed in 2008 and was about 230 higher, on the same vertical shaft.

The new vertical shaft, 28 feet in diameter and 240 feet high, connected with the existing shaft, 20 feet in diameter, previously completed to a depth of 3,089 feet in 1983. The copper and gold deposit had been initially explored in the early 1980s with 12,300 feet of horizontal tunnels, known as "drifts," along with continuing to drill exploration holes. In the mid 1980s the vertical shaft accessing the North Ore Shoot, along with the former Anaconda Carr Fork mine (sold to Kennecott in 1985), were abandoned and allowed to flood. The shaft was sealed at the top and the headframe was removed.

The recovery of the North Ore Shoot vertical shaft in 2007-2008 included a new headframe, which, as of June 2021, remains on the site near the 6190 truck shop.

Timeline

September 1980
Work began on the North Ore Shoot Extension, mining ore for the production of copper, gold, silver, and molybdenum. A study completed in 1980 projected that the Bingham Mine would have to convert partially to underground operations and build new concentrators. Development of the North Ore Shoot included a new headframe and hoist house, and a 4200-foot vertical shaft, together with underground "service stations." The construction of the vertical shaft and attendant surface structures, including a large headframe and hoist house, was contracted to Harris & Western of Denver. At a reported cost of $30 million, the contract was to last for five years, until 1985. (Salt Lake Tribune, November 19, 1980)

The headframe for the North Ore Shoot project was in place at the time of photos dated August 1978.

By using exploration drilling, Kennecott discovered the North Ore Shoot in 1957, but the full extent of the ore body was not yet known, and current open pit mining operations remained as the focus of the company.

Kennecott's North Ore Shoot development project was separate from the overall open pit operations, and did not shut down in July 1984 with all of the other parts of Kennecott's Utah operations. Research suggests that the underground development was in the hands of a Kennecott subsidiary called Kennecott Copper and Gold Mining Co.

March 18, 1981
"Development of the so-called North Ore Shoot Extension, a high-grade deposit of copper, gold, silver and molybdenum several thousand feet under the northeast shoulder of the Bingham pit, began in September. A 4,200-foot shaft is being sunk to press development of the North Ore Shoot." (Salt Lake Tribune, March 18, 1981)

1983
The North Ore Shoot has a total of three shafts. Subsurface depth reaches a maximum of 4,265 feet (1,300 meters). The mining method is horizontal cut and fill with waste rock. Mine capacity in 1983 was 12,125 tons (11,000 metric tonnes) per day. At some point, the North Ore Shoot, and Carr Fork mine, were combined under a new name, Bingham Canyon Underground. But most people continue to use the North Ore Shoot name.

September 13, 1990
Kennecott's North Ore Shoot project was still being developed, but the high cost of underground mining was deterring any action beyond continued development work. (Salt Lake Tribune, March 18, 1990)

1993-2006
Although the North ore Shoot project had been shut down in the mid 1980s, aerial photos from 1993 show the headframe still in place. By 2005 aerial photos show that the headframe had been removed and the area had been reconfigured as waste rock dumping grounds. By the end of 2006 the area was being used for storage of machinery and equipment.

The North Ore Shoot shaft was allowed to flood after it was abandoned in 1986. In June 1998 Kennecott began pumping water from the North Ore Shoot shaft, preparing to resume development work. By 2001, the pumps were removing 1,100 gallons per minute. With the bottom of the North Ore Shoot shaft being over 1,000 feet below the bottom of the open pit mine, the pumping had the added benefit of dewatering the bottom of the pit itself. A year later, in July 1999, Kennecott began pumping water from the bottom of the former Anaconda Carr Fork mine. By 2001, the Carr Fork pumps were removing 1,500 gallons of water per minute.

2008
Contractors completed the recovery of the North Ore Shoot. In 2007 Kennecott Utah Copper contracted with Atkinson Construction LLC of Golden, Colorado, at a reported cost of $44.5 million, to recover its North Ore Shoot vertical shaft that was built in the early 1980s but had since been capped, backfilled, and abandoned at the end of the five-year development period in 1985. In 2007, to uncover the old shaft, crews excavated a 230-foot-deep, 28-foot-diameter shaft through unconsolidated waste rock fill to an existing heavily reinforced concrete shaft collar.

Once the recovery of the vertical shaft was complete, Atkinson installed a new shaft collar and concrete liner throughout the new excavation, removed the existing shaft collar and dewatered the 3,300-foot-deep, 20-foot-diameter shaft. Late in 2007 the scope of work expanded to include a permanent headframe structure, construction of all surface infrastructure, and a complete retrofit of the underground facilities. The project included the installation of a dirty water pumping system, steel shaft lining, a ventilation system, and development of underground stations.

The new headframe is a hybrid headframe, supporting both a tower-mounted friction hoist, for service and maintenance, and two drum hoists, one for production and the other as an auxiliary.

In 2011 additional rehabilitation work was begun, including upgrading the utilities and steel shoring in the original 1980s shaft down to the 4500 level (4,500 feet above sea level), which was brought up to current standards. An additional 7,000 feet of drifts were begun to support additional feasibility studies.

The work to rehabilitate the North Ore Shoot shaft came to an end in 2014, and the reseources (men, equipment, funding) were diverted to recover from the Manafay slide that had occurred in April 2013. Although the headframe and surface buildings are still in place, as of June 2021, the project is essentially closed.

Anaconda Carr Fork

September 7, 1974
Anaconda announced a new project to begin mining copper from a new underground mine to be located about two miles west of Kennecott's Bingham open pit mine.

The headframe for the exhaust shaft of Anaconda's Carr Fork mine was located on the Bingham side of the ridge, on a pad situated on the north side of the old Carr Fork county road, about 1,000 feet up-canyon from the Kennecott observation platform. The headframe was not yet in place at the time of a photo taken in June 1975, but was completed by the time of photos taken in August 1975. The headframe was missing in a photo taken the area in October 1982, with the headframe being removed and replaced by an exhaust fan housing.

January 1977
In January 1977, Atlantic Richfield Company (ARCO) purchased the all interests of Anaconda Copper Mining Company.

October 1982
Anaconda closed its Carr Fork underground mine, after just three years of operation.

November 1, 1984
Kennecott and Anaconda announced a joint venture that would resume production from Anaconda's Carr Fork underground mine. Kennecott was to be the operator and would receive 96 percent of the production, with Anaconda receiving the remaining four percent. The Carr Fork concentrator had a 10,000 tons per day capacity, but the mine never reached that number in its production.

October 1985
Kennecott purchased all of the Anaconda's interest in the previous joint venture, as well as Anaconda's other properties at Bingham.

(Read more about Anaconda's Carr Fork Project)

###