Canadian Mining Journal


Small town mines dig deep to produce potash in a big way

Fifty years ago last month, in September, 1962, to be precise, the first few tonnes of potash were hauled to the surface from the K1 mine, just outside the small town of Esterhazy, Sask., located some 180 kilometres east of Regina. In the half...

Fifty years ago last month, in September, 1962, to be precise, the first few tonnes of potash were hauled to the surface from the K1 mine, just outside the small town of Esterhazy, Sask., located some 180 kilometres east of Regina. In the half century since then, billions of tonnes of ore have been produced.

A second mine, called K2, has been built and some 4,500 kilometres of tunnels have been dug in order to tap the vast deposits that lay some 1,116 metres beneath the flat, wind-swept, grain-producing prairie of southeastern Saskatchewan.

Now, The Mosaic Company of Plymouth, Minn., owner of K1 and K2, is developing a new, $1.6-billion satellite mine known as K3, which is slated to begin producing in 2016 and is expected to ramp up to full capacity by early the following year.

Mosaic is undertaking this major expansion project for two reasons; one local, the other global.

Operating efficiencies at the K1 and K2 mines have declined as the underground works have expanded.

Gerry Couture, Mosaic’s Vice-president of Engineering and Expansion, notes that many workers now routinely travel 10 kilometres from the bottom of the shafts to the mine faces where the ore is extracted. Likewise, ore then has to be hauled the same distance back to the shaft before it can be lifted to the surface for milling and processing.

The new mine will, at least in the early stages, reduce travel times and boost productivity.

The bigger issue is the global demand for potash-based fertilizers. Current demographic and economic trends indicate that consumption of these products will rise steadily for the next half century.

The world’s population is growing at a rate of some 75 million people annually. China, India and other less-developed countries are rapidly industrializing. Their citizens are becoming more prosperous and demanding better foods. At the same time, agricultural land bases in many of these nations are shrinking or, at best, remaining stable. Hence, yields will have to increase dramatically and fertilizers are an essential part of the equation.

Engineering and design work on the K3 mine began in 2008 and construction is now well advanced and more or less on schedule, says Couture.

“We’ve had some very wet springs and we had to re-sequence some of the activities,” he says. “Overall, we are still on track to start production in 2016.”

One of the big challenges is a natural phenomenon known as the Blairmore Formation, which is located 310 to 372 metres below the surface and is up to 124 metres thick. It is a sandy structure that is saturated with brackish water and, according to some observers, resembles quicksand.

Back in the 1950s, it confounded every effort to sink shafts through it and held up efforts to develop the vast potash reserves beneath it. As soon as mining companies penetrated the formation, the gooey substance oozed into their excavations and continued to flow until reaching the surface.

The Esterhazy K1 shaft was the first to be sunk successfully, but this occurred only after the company that was developing the mine imported a German freezing technology that allowed it to create a wall of ice around the excavation. The shaft-freezing technology has been used throughout the Saskatchewan potash industry ever since and is being employed at the K3 site.

Early in the new year, outside contractors will begin digging two shafts to depths of about 1,085 metres; one to move workers, equipment and ore, the other for ventilation and emergency exits. Each will be 6.2 metres in diameter and they will be about 140 metres apart.

Couture says the company has already completed the shaft freezing for the full depth of the Blairmore Formation. It drilled and sank 72 freeze pipes and built refrigeration plants that circulate a coolant similar in appearance and viscosity to automobile anti-freeze. The freezing process creates circular walls of rock-solid ice at temperatures of about minus 35 centigrade.

Some 400 construction workers have been employed at the site for months and most were building surface structures–the most important and impressive being the massive 116-metres high headframe, which was well advanced by mid-September.

A pit, 25 metres square by 16 metres deep, had been dug for the foundation. Piles had been sunk to a depth of 23.25 metres and a 1.9 metre-thick concrete pad had been poured. Crew then worked round the clock for 18 days pouring concrete and raising the walls of the headframe to a height of 93 metres above surface. Additional structures will be built on top of the concrete walls to house the hoist and the electrical unit that powers it.

K3 will be a satellite mine, located about l0 kilometres from the existing operations and the ore will be hauled by truck to a milling complex at K2. Mosaic’s Esterhazy operation is one of three the company owns in Saskatchewan; the other two being at Belle Plaine and Colonsay, and it is the largest potash producer in the world. As part of a broader expansion program, the company has added 100,000 tonnes per year additional milling capacity at K1 and it has boosted the capacity of it K2 compaction plant by 400,000 tonnes per year.

K3 will add significantly to the overall output at Esterhazy. The existing mines produced 6.7 mllion tonnes of ore and 2.3 million tonnes of finished product in the fiscal year that ended May 31, 2010.

In the most recent fiscal year, which concluded May 31, 2012, they turned out 12.4 million tonnes of ore and 4.0 million tonnes of finished product. In its first full year of operation, K3 is expected to yield about 3.0 million tonnes of ore and one million of finished product.

“This mine could easily and rapidly be expanded to the point where we’re producing 21 million tonnes of ore and seven million of finished product if and when required though we may have to upgrade the milling facilities,” says Couture.

In any event, one thing appears certain. Esterhazy will retain its title as the self-proclaimed Potash Capital of the World for the foreseeable future.

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