One example of an older concrete silo is the Parrish & Heimbecker grain terminal in Winnipeg (Transcona) Manitoba. This 22,400-metric-ton facility was built in 1913 and is quite famous in geotechnical circles because the soils under the silos failed during initial loading, causing the silos to tilt. The foundation problems were solved, the grain elevator was righted, and it is still in use.
But I would imagine there are other examples much older than 1913. The Peavey-Haglin experimental concrete grain elevator in Minnesota was poured in 1899–1900, although it never stored grain (see www.mnhs.org/library/history_topics/70peavey.html). The Lakehead Terminal at Thunder Bay, Ontario, reports its first concrete grain elevator in 1903 (http://collections.ic.gc.ca/civileng/eng/details.asp?id=18).
—Derek van Nes, EIT, Manitoba Hydro, Winnipeg, Manitoba