BY DAN HILDEBRAN
Monitor Editor
STARKE— Since the 1920s, residents and visitors to Kingsley Lake noticed that among the course white sand along the lake’s beaches, thin streaks of a black, silky substance could also be seen lacing through the pearly granules.
The black substance was ilmenite.
After processing, ilmenite becomes titanium dioxide, a pigment used to whiten products from toothpaste to paint.
Before World War II, E.I. DuPont de Nemours and Company imported all of its ilmenite ore from southwest India. However, political unrest there prompted the company and the U.S. Bureau of Mines to search for a domestic source, and that search led the organizations to the shores of Kingsley Lake.
In 1946, the bureau surveyed a low-grade ilmenite deposit from 3,000 to 8,000 feet wide, 35 to 60 feet deep, and 19 miles long, stretching northwest from the Keystone Heights area lakes to Baker County.
The area followed the Trail Ridge, part of a series of ridges reaching up to 250 feet above sea level from the west side of the Okefenokee Swamp to Lake Okeechobee, said to be used by Native Americans traveling up and down Florida’s peninsula.
There was one problem, however. The sand under Trail Ridge contained only four percent ore, compared to the 75-percent concentration in India. That low grade made mining of the Florida mineral economically unfeasible.
But DuPont overcame that limitation by utilizing technology developed in a Denver, Colorado garage by Ida Boyd Humphreys.
During 1941, beginning with used tires and then fashioning sheet metal, Humphreys developed a process he thought would improve the efficiency of extracting gold from the sediment in the streams west of Denver.
For 83 years, prospectors had been panning the streams leading down from the Rockies. In gold panning, a prospector would scoop up sediment and water into a pan, then separate the sand from any ore in the sample by swirling the sediment around in the water.
Humphrey’s idea was to scale the panning process, funneling the water-sediment mixture into a series of circular pathways, creating the same effect as a centrifuge, separating the lighter sand from any heavier metals in the sample.
The result of Humphrey’s work was the spiral concentrator. Even though the innovation was never widely used in gold mining, the process allowed DuPont to turn the worthless four-percent Trail Ridge sand into a money-making enterprise.
In 1947, DuPont leased 4,000 acres within Camp Blanding from the Florida Armory Board, contracted with Humphrey’s Gold Corporation to build and run spiral concentrators assembled in a wet mill, and began operations the following year.
Over the past 70 years, workers ranging from 200 to over 300 have operated a dredge and wet mill from Camp Blanding toward Macclenny. Until recently, the operation was based in Baker County, along County Road 228, approaching Interstate 10.
Other minerals mined from Trail Ridge include zircon: which is used in the sand foundry industry; zirconium, which is used to coat the inside of nuclear reactors, jet engines and space vehicles because of its heat resistance; and staurolite, used in the making of concrete and in sandblasting.
In 2015 DuPont spun off its performance chemicals division, which included its Florida mines, into a new publicly traded company: Chemours.
Today, Chemours operations in northeast Florida generate $50 million yearly in economic impact and provide over 225 jobs.
Last week, the mining operation entered a new phase, with Chemours dedicating its new $93 million plant at Trail Ridge.
The plant replaces the former wet mill but still uses the spiral concentrator technology Ida Boyd Humphreys developed during World War II.
The new plant also replaces the operation’s previous dredge with mobile mining units, allowing the company to reach ore the dredge could not access. Operated remotely with controllers using a tablet device, the mobile mining units also increase safety and minimize environmental impact by lowering emissions and decreasing water use in mining operations.
