Rock burst—a spontaneous, violent fracture of rock that can occur in deep mines—is a serious hazard. It occurs when underground excavation relieves neighboring rocks of tremendous pressure, which can literally cause the rock to explode as it attempts to re-establish equilibrium. Miners are killed worldwide each year from this geologic phenomenon.
U.S. Silver & Gold’s Galena mine, located in Wallace, Idaho, USA, is a 5,800-ft-deep (1,767-m) silver-copper-lead mine that produces approximately 900 tons of ore daily. The mine has had consistent seismic activity since the late 1950s. Fiber optic cable from Optical Cable Corp. (OCC) has helped the mine monitor and manage these seismologic changes, resulting in zero deaths or injuries related to rock bursts since 2001.
The Galena mine’s original installation consisted of OCC B-series Mine Safety and Health Administration-rated deployable mining cables. The 6-strand fiber optic cable, installed to a vertical depth of 4,600 ft (1,400 m), served as part of a seismic monitoring system. At the time, it was believed to be the world’s tallest vertical mine cable installation.
“Prior to the OCC cable installation, the Galena mine had one of the more advanced monitoring systems for its time, but it was dependent on manual processing from the underground office,” said Kathryn Dehn, senior rock mechanics engineer. “Today, real time monitoring of seismic activity in the mine allows us to alert workers if a problem is detected, so we can pull them out of an area until the rock stabilizes. It has helped reduce injuries and prevent accidents.”
Dehn said prior to 1992, seismic activity was monitored by staff located in an underground office who performed critical calculations by hand. Thanks to OCC fiber optic cable, mine operators now can monitor and fix problems from the surface—and even from remote locations, using a laptop.
“Communication and monitoring via fiber optic cable has revolutionized mining safety and operation,” said Dehn. “We have a far better picture of what is happening a mile below the surface and can monitor and correct situations in real time that may otherwise have resulted in accidents in the past.”
Dehn said that a new 4-strand cable was hung at the Galena mine in 2001 for additional monitoring, and an additional 6-strand cable installation is in progress to accommodate upgrades and to allow for future expansion. In 2010, the mine also installed 2,000 ft (610 m) of additional 4-strand cable to expand the system.
“We chose to stay with OCC cable because it survives,” she said. “Our choice has always been MSHA deployable cable because it has never failed, even though we operate in the harshest of environments.”
According to OCC, its B-Series MSHA-rated deployable mining fiber optic cables are designed to provide reliable communications and monitoring in hazardous and harsh mine environments. Major features include:
• OCC’s polyurethane Core-Locked jacket, extruded under high pressure directly over the cable’s core, resulting in a cable that has no voids and acts as one unit when bent or twisted.
• Helically stranded cable core for flexibility, deployment, survivability and mechanical protection for the optical fibers.
• Color coded sub-cables for direct termination.
• Crush-resistance and resiliency, with two separate layers of aramid strength members in the sub-cables for individual single-fiber connector or termination pin, and an overall layer for strain relief on multichannel connectors.
Normet Buys D-Bolt Developer DRS
Finnish underground mining and tunneling equipment specialist Normet Group Oy recently acquired Dynamic Rock Support (DRS) AS, another Nordic company that will enable Normet to offer enhanced rock reinforcement solutions via DRS’s new generation, energy-absorbing D-Bolt system. DRS is based in Trondheim, Norway, and has subsidiaries in Australia and Canada.
According to DRS executives, the company's main focus has been on providing reliable technology that ensures safety and provides cost savings for underground mines, particularly where challenging ground conditions involve squeezing or dynamic risk management. DRS has developed the D-Bolt, a novel rock bolt specifically designed for rock reinforcement in squeezing and burst-prone strata.
DRS will be integrated into Normet’s Rock Reinforcement business line. Mike Rispin, senior vice president of Normet Group, said, “Focus will be maintained on bringing the innovative technology of the D-Bolt to our existing and new customers. Blended with our expertise in resin- and cementitious-based bolt grouts, and coupled with a proven track record in rock mass reinforcement via injection, we offer an unparalleled array of solution offerings.”
“This acquisition is a good strategic fit to Normet as it broadens our offering to underground customers and reinforces our aim to be a total solution provider especially in ground support and rock reinforcement,” Tom Melbye, president of Normet Group, said. “With the D-Bolt system, together with our sprayed concrete, grouting and injection technologies and products, we can now help our customers make underground mines and tunnels safer, even in difficult strata and high stresses and deformations.”
Normet said following successful laboratory and field tests, that began in 2008, and the start of commercial sales in 2010, DRS has gained a strong market share of rock support business, particularly in the Nordic region, Canada and Australia. A recent presentation by a company representative indicated that the D-Bolt was in use, being evaluated, or receiving interest from a number of operators. According to the presentation, it is currently in use to control rock-burst conditions at LKAB in Sweden, used in “squeezing-ground” conditions at Boliden and at three Canadian mines for squeezing and/or seismic conditions. It also is being tested at six other Canadian mines, at a large mine in Chile, and has been involved in ongoing evaluation from BHP Billiton in Australia.
The bolt itself comprises a smooth steel bar with several oval-shaped, double-paddle-type “anchor” points along its length. The bolt is grouted, or fixed, only at the anchor points, leaving the smooth sections between the anchors to freely deform. The bar, according to DRS, is manufactured from special steel with enhanced mechanical properties that provide high strength and ductility. D-Bolts are available in 22.2 and 20.5 mm diameters, in lengths from 1.8 to 3.2 m, and with M24 threads for the larger diameter bolts and 7/8 in. UNC threads are used for the smaller diameter version.
“We believe that Normet, which shares DRS’ focus on quality and improving the safety of underground workers, is a very fitting host for DRS,” said Gisle Østereng, CEO of Dynamic Rock Support AS “With the backing of Normet’s worldwide organization, the technology and expertise fostered by DRS will continue to impact mining and tunneling operators with world-class ground support and rock reinforcement products.”
Financing is Secured for Magnetation’s New Plants
Magnetation LLC announced on May 21 that it had successfully completed a $325-million senior secured notes offering and has entered into a $50-million senior secured credit facility. The proceeds from the notes offering will be used for capital expenditures to construct a new concentrate reclamation plant northwest of Coleraine, Minnesota, USA, and a 3-million-mt/y plant in Reynolds, Indiana, to produce high-quality iron ore pellets. Production from the pellet plant will supply AK Steel’s blast furnaces located in Ohio and Kentucky.
In addition, Magnetation announced it had received a $50-million contribution from AK Steel as part of AK steel’s remaining $150-million commitment to Magnetation. Thus far, AK Steel has invested approximately $200 million of a planned $300 million. AK Steel will contribute the final $100 million during 2014 or as needed to support the construction of the new pellet plant.
Larry Lehtinen, CEO of Magnetation, said, “With this financing secured, we anticipate producing high quality fluxed pellets during the fourth quarter of 2014. Upon startup of the pellet plant and Plant 4, Magnetation will become a four million tonne per year iron ore producer employing about 500 people, providing high quality iron oxide pellets to AK Steel, low residual iron ore concentrate to AHMSA of Mexico and high grade iron oxides to various specialty market customers.”
Magnetation LLC is a joint venture between Magnetation, Inc. (50.1%) and AK Steel Corp. (49.9%). Magnetation LLC reclaims iron ore concentrate from previously abandoned iron ore waste stockpiles and tailings basins. Currently, Magnetation LLC owns and operates two reclamation plants located in Keewatin and Taconite, Minnesota, respectively.
Metso to Spin Off Pulp & Paper Business, Keep Mining & Construction
Metso Corp. announced at the end of May that it plans to transfer all of the assets, debts and liabilities of its pulp, paper and power businesses to a newly formed company that will be named Valmet Corp. An application will be made to list the shares of Valmet on the NASDAQ OMX Helsinki stock exchange. Following the demerger, Metso’s mining and construction and automation businesses will remain in the current company, which would continue to operate under the Metso name. Valmet would be independent, without any cross-ownership between Metso and Valmet.
The move follows a strategy study conducted by Metso’s board of directors that indicated going forward with a “demerger” would offer the pulp, paper and power businesses, as well as its mining and construction and automation businesses the best opportunities to utilize their respective strengths in their specific industries.
According to a Metso press statement, the increased management and board focus should help the two independent companies achieve stronger growth and improved profitability. This would also be expected to result in increased value for shareholders inasmuch as both companies would have their own distinct characteristics and would offer different investment profiles.
The demerger will require the approval of an extraordinary general meeting of Metso and the registration of the completion of the demerger with the Finnish Trade Register following the creditor hearing process pursuant to the Finnish Companies Act. If approved, the planned registration date of completion of the demerger is December 31, 2013, and public trading in new Valmet shares on NASDAQ OMX Helsinki is expected to commence as soon as possible thereafter.
Metso will propose at the extraordinary general meeting that the Metso board would, after the completion of the demerger, partly consist of those of its current members who will not become members of the Valmet board, and partly of one or more new members to be elected by the extraordinary general meeting.
Upon registration of the completion of the demerger, Metso shareholders would receive, as demerger consideration, one share in Valmet for each Metso share that they hold. No action would be required from shareholders to receive this demerger consideration, according to Metso.
Jukka Viinanen, Metso’s chairman of the board, said the board of directors recommends that shareholders approve the demerger. “After carefully reviewing various alternatives that would accelerate the implementation of Metso's strategy and its growth, the board has concluded that spinning off Metso’s pulp, paper and power businesses through a demerger offers the best potential to increase the focus and ambition of Valmet and Metso and the implementation of their respective distinct growth strategies. The board believes that this, together with the creation of two attractive investment alternatives, would also create strong potential to increase value for Metso's shareholders.”
Metso released certain key financial figures for each proposed company based upon consolidated pro-forma balance sheets and income statements as of and for the year ended December 31, 2012. The figures show:
• Metso Corp. with total assets of €4,005 million, total equity of €1,362 million, gross debt of €1,095 million, net debt of €388 million, net sales of €4,499 million, and EBITA before nonrecurring items of €496 million.
• Valmet Corp. with total assets of €2,637 million, total equity of €865 million, gross debt of €195 million, net debt of €-72million, net sales of €3,005 million, and EBITA before nonrecurring items of €192 million.