Engineering & Mining Journal

APR 2019

Engineering and Mining Journal - Whether the market is copper, gold, nickel, iron ore, lead/zinc, PGM, diamonds or other commodities, E&MJ takes the lead in projecting trends, following development and reporting on the most efficient operating pr

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Page 35 of 83

WASTE MANAGEMENT 34 E&MJ • APRIL 2019 Mine operators expect to encounter unan- ticipated incidents throughout the life of a project. It could be an outcome of a bad decision in an early stage of development, an unexpected natural event, or a shift in the regulatory framework. Maybe the drill- ing contractor pulled cores that were too small in diameter to provide valid crush- ing samples during the testwork phase. Or, years of unprecedented drought shrink a once abundant water supply to a trick- le. Changes to mining taxes and royalties can hinge on the outcome of an election. That's why risk management advice is an industry growth sector. The flip side of this coin represents project "constants" — expectations of continuity, such as processes that might be tweaked but not abandoned, steady increases in haulage fuel burn as min- ing goes deeper, or an inevitable rise in process-energy demands as ore grade di- minishes. One of the most tenacious con- stants is waste generation: Where there is mining, there will be waste. It can take the form of waste rock, tailings, water, sludges or slurries, and discarded consumables ranging from worn-out conveyor belts or gi- ant equipment tires to pallets, drums and miscellaneous trash. The corollary to this constant is that pressure on mineral pro- ducers to reduce, control and even profit from waste is only going to get stronger. The rising tide of mining-related waste generation stemming from growing world demand for mineral commodities, cou - pled with declining ore grades, also has lifted waste management into the cat- egory of growth sector. Market studies predict — albeit with sometimes wildly differing figures — steady increases in the global mine waste-management mar- ket size. One recent study estimated that the waste-management market size just for rock and tailings will rise to almost 18 billion tons worldwide between 2018 and 2022, with growth accelerating at a Combined Annual Growth Rate (CAGR) of 5% during that period. Another predicts a CAGR of 6.1% with a total market size of more than 233 billion tons by 2022. How closely the industry actually follows those predictions remains to be seen. Teck Resources, for example, is Canada's largest diversified mining com- pany, with copper, zinc, metallurgical coal and oil sands operations located in Canada, Chile, Peru and the U.S. Ac- cording to the company, its operations produced about 917,000 metric tons (mt) of mineral waste in 2017, most of it coming from ore and coal extraction. In 2018, that amount increased to roughly 928,000 mt, a gain of slightly more than 1% over the course of a year. Although the production and primary handling and storage of rock waste and tailings accounts for the lion's share of tonnage and attention from large produc- ers, that topic is beyond the scope of a single article. This month, E&MJ looks at a few facets of the "re"-segment of mine waste management — as in recycling or re- use of once-discarded materials. And yes, it too represents a modest but increasing- ly significant growth sector, as part of the "circular economy" model that's driving commercial interest in this area. A Circular Approach The main premise of a circular economy involves minimizing waste and obtain- ing maximum value from resources, and recycling is a major foundation block in the model. Teck, for example, noted in its 2018 Sustainability Report that it recy- cles waste materials, buying certain types of e-waste such as cathode ray tubes and alkaline batteries for processing at its Trail, British Columbia, smelting/refining complex. And it recycles its water — up to four times at some operations. Other producers pursue similar strate- gies. Rio Tinto said its Kennecott Copper operation in Utah has, since 2012, added recycled scrap metals such as old copper wiring into the smelting process. In 2017, Kennecott processed 2.8 million lb of cop- per from recycled scrap metal. Its Oyu Tol- goi operation in Mongolia currently recycles more than 80% of its water, which, in terms of water-per-ton-of-ore processed, means it uses less than half the global average of similar mines, according to the company. In Sweden, Boliden has recycled waste at its Rönnskär smelter since the 1960s. The refinery, outside Skellefteå, has an annual capacity for recycling electrical material of 120,000 mt, including circuit boards from computers and mobile phones sourced principally from Europe, reported- ly making it one of the world's largest recy- clers of metal from electronic material. Programs like these shift the industry a small step closer to the concept of urban Shrinking the Waste Line Producers and service providers are mapping out pathways to more eco-friendly handling of mining's solid-waste materials ranging from tires to trash By Russell A. Carter, Contributing Editor The number of mining tires scrapped annually is a tiny fraction of the total volume of scrap tires, but they carry disproportionate weight-to-numbers: In the U.S., for example, OTR tires account for about 1% of scrap tires by number, but 15% by weight.

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