The next videos that will be completed for the Elements Unearthed Project are two episodes on the sources, mining, refining, and uses of beryllium. I’ve written a few posts previously about this topic, and as I continue to organize and prepare materials to use in the videos (which will be edited over the next week), I have created several diagrams that describe the process used for surveying and developing open pit mines at the Brush Resources’ Spor Mt. mine site in western Utah. You might say, “Beryllium? Why should I care about some rare metal that I’ll never use in my lifetime?” But you’d be surprised. You are already using beryllium (for example, the electrical contacts inside the automatic windows of your car use a beryllium-copper alloy because it can handle frequent changes in heat and resists corrosion better than many other alloys). Beryllium is also an essential metal for medical, nuclear power, and aerospace applications. I’ll discuss more of beryllium’s uses and its refining and sources in a later post, but in this post let’s talk about how the bertrandite ore is mined.
Location of Bertrandite in Western Utah
Mining Operations at Brush Resources
The bertrandite ore found in the Spor Mts. is very similar to clay (an aluminum silicate) and looks like common dirt except it has a slight pinkish color. It’s also associated with fluorspar or fluorite, which is often a deep blue to violet color. One is tempted to think the more colorful fluorite is the mineral we want, but it’s actually the crumbly pink coating found on the fluorite nodules. Elsewhere in the Spor Mts., the fluorite has been mined commercially.
The first attempt at mining the bertrandite ore was started by Anaconda on their claim. They tried hard rock mining, but the soft altered rhyolite of the ore body proved too dangerous to mine that way. One day, while the miners were all having lunch, the mine caved in. Fortunately no one was hurt, but it was determined then that the only safe method was open pit mining.
Exploratory core drilling
Potential mine sites are surveyed by drilling core samples every 100 feet to map out the general location of the ore bodies. The bertrandite deposits in the Spor Mts. are located in a mineralized zone of altered rhyolite tuff that overlies a bedrock of limestone. This soft and crumbly altered layer is overlaid by a tough, hard layer of unaltered rhyolite with about the same composition and hardness of granite. All of this is further overlaid by a layer of gravel, loose rock, and sand deposited by Lake Bonneville during the last ice age. Since the ore body is tilted, it occasionally reaches the surface (where it was originally discovered) and in other places dips so far below ground as to be unfeasible to mine. Several mine sites, such as the Blue Chalk and Roadside I sites have already been mined, but enough reserves have been mapped to last at least 50 more years at current production levels.
Planning an Open Pit Mine
Once the location of the ore body has been generally mapped out, mining engineers plan out an open pit structure that will reach the ore with the least disturbance to the overlying layers while keeping the sides of the pit terraced to safely prevent rockslides and excessive erosion. Once the plan is approved, a contractor is hired to remove the overburden, usually in the winter and spring months. The loose alluvial gravel and soil is removed first and set aside for later reclamation. The hard rhyolite is blasted and removed, and the altered rhyolite layer is also removed to within about seven feet of the bertrandite ore.
Removing the Overburden
A second phase of core drilling is carried out, with holes every 25 feet to more accurately map out the exact ore locations. For a typical ore body, between 40 and 60,000 cores are drilled and sampled every two feet. 3D structural maps are prepared to identify where various grades of ore are located. The ore is then removed carefully; a technician with a portable field berylometer walks before the bulldozer and stakes out the locations of the ore grades that are being removed; a self-loading scraper scoops up the ore and moves it to stockpiles where it is sorted by grade into the same pile. The ore is then transported by 18-wheeler to the processing plant near Delta, Utah, about 50 miles southeast. High-grade ore is mixed with low-grade ore so that all the bertrandite coming to the plant has about the same percentage of beryllium. The final ore has less than .65% beryllium, or about four pounds per ton.
Next Post: Refining Beryllium Ore
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