By Susanna McLeod
Special to Ontario Construction News
The earth’s crust is a treasure chest laden with sparkling riches. Gold and precious metals. Diamonds and a rainbow of stones. Thick, sticky oil and sand soaked in petroleum. And specific regions hold a mineral almost as vital to life as water. Salt.
In the 1850s-60s, the electricity of oil fever was sparked when petroleum was found at Lambton County, southern Ontario. Flour-milling businessman Samuel Platt was determined to make his fortune in oil by establishing the Goderich Petroleum Company in 1866. Raising the then-huge sum of $10,000 and taking partners, Platt drilled to nearly 210 metres on the shore of the Maitland River near Lake Huron. The crew found nothing.
“The partners walked and Platt nearly gave up,” said Phil Egan in the Sarnia Journal: Then and Now, August 29, 2015. “But the town and county chipped in $1,500 to keep the drilling going.” Reaching 293.83 m, the drill bit struck paydirt. But it wasn’t viscous, it wasn’t black. The 18-metre-thick layer was sparkling white. Platt struck salt.
Platt was surprised, geologists had previous calculated that halite—sodium chloride—would be located in the area. “The Geological reports of Sir William Logan early announced that the Onondaga group of salt rocks of the Silurian series (about 440-420 million years ago) underlay the drift and limestone of a part of western Ontario,” stated Picturesque Canada (1882), quoted H. Najiya and J. Cole in “Salt,” University of Waterloo Earth Sciences Museum.
“The salt was solidified, under conditions hard for us to imagine, and in quantities sufficient to supply this continent for ages,” Picturesque Canada said. Chemical analysis in the 1860s “indicated that the salt was the purest known, and the most concentrated possible.”
Realizing the remarkable significance, the industrialist wasted no time in altering his firm name to Goderich Salt Company. With the additional money, “Platt started a salt recovery plant which began production in 1867, turning out 100 barrels, or 13.5t (15 tons), a day,” according to David Spencer’s Education Paragon. Platt’s find “became the first recorded discovery of a salt bed in North America.”
Nearly a dozen other companies rushed in, creating a mineral boom. The salt was extracted by pouring water into the drill holes and hauling up brine. Boiling the brine in cauldrons to evaporate the water, the remaining salt was packaged and sold. In 1867, Platt entered his product in the Paris Exposition in France. His Ontario salt won first prize.
Mass production of salt began in 1880 with “workers placing rows of 100 cast iron kettles, carrying 120 to 140 gallons of pumped brine each, on wood burning furnaces,” described Mining Life. Production of the flaky mineral was expensive. Modernization by 1910 changed the system to a “vacuum pan process” with “one vertical steel tank with internal heating tubes conducting steam.” The remaining salt was granular, perfect for table salt.
Attempting to construct a salt mine along with the wells, Platt’s firm ran into trouble; Lake Huron’s fresh water kept dousing the mine. He gave up and closed the mining venture.
Several decades later, another company undertook construction of a salt mine at Goderich. In 1959, Sifto Canada engineers constructed a 550 m shaft (1,804 feet) to mine rock salt for water softeners and road safety. More shafts followed with their underground depth extending under Lake Huron. Today, the mine invisibly stretches out three kilometres from the shoreline.
“The salt bed is about 100 feet thick [30 m] and it is virtually impermeable,” wrote Canadian Mining Journal in “Deep and Dry,” Feb. 1, 2013. Even with 30 to 45 metres of lake water overhead, mine workers securely “cut into the floor of the deposit, drill holes, insert dynamite and then detonate.”
Why is salt so valuable? There are countless applications for the mineral. Vital for human body regulation, it keeps electrolytes in balance and dehydration at bay in a blend of water and salt. Plants, fish, and animals require salt to live and thrive.
Along with seasoning and preserving food, salt is used in manufacturing processes including tanning and dying, and water purification. Rock salt on icy roads and sidewalks makes driving and walking possible on slippery days. Some hardworking soldiers in ancient Rome received their pay in the mineral, suggesting that they were “worth their salt.”
Today, Sifto Salt Canada’s mine at Goderich (a division of Compass Minerals) is considered the largest underground salt mine in the world. “Huge rooms have been carved to use as storage for heavy equipment and vehicles,” said Canada Salt Group Limited, and “rooms are also made for the workers to have lunch and take rest.”
Shearing salt from mine walls with job-specific cutters, the loaders, trucks, and conveyor belts transport the raw mineral to mills, producing more than 7 million tons of salt per year. Pass the saltshaker, please!
© 2021 Susanna McLeod. McLeod is a Kingston-based freelance writer who specializes in Canadian History