FMC Wyoming is the largest of four companies operating in the region, which together mine roughly 15,000,000 metric tons of trona each year and produce over 8,000,000 metric tons of soda ash.
To smooth out these variations in the ore FMC engineers needed to detect the troublesome ore, divert it from the process stream, and then meter it back into the process in a controlled way. In order to segregate the high-insoluble ore and control its delivery, a large underground storage and handling system was needed, allowing operators to better control the flow of ore to the surface.
Jenike & Johanson's Solution
Jenike & Johanson evaluated the feasibility of reliably handling the trona ore in two 1,300 ton capacity silos to be constructed underground. Flow properties tests on the trona confirmed what most operators knew: when stored at rest trona crystals grew together and formed a hard, solid mass. The tests provided the information necessary to design the silos for mass flow, which prevents stagnant, non-flowing regions where the trona could cake together.
Building two 25 foot diameter silos and a 200 foot conveyor system at a depth of 1,800 feet below the surface provided many challenges! Construction materials were evaluated for abrasive wear, loads were calculated on the structure and feeder, and a unique diverter was designed for the in-feed conveyor system.
The Result
Since startup in early 1998, the system has been operating reliably and has allowed the mine and processing plant to work together more efficiently and reduce production costs. "The bins are performing very well", according to Dan Moulden, a senior engineer at FMC Wyoming. "When we inspected the material through the bin blaster nozzles in the hopper, the material could be seen moving along the hopper walls, which is a clear indication of mass flow. The insolubles are being detected, separated, and fed back into the stream at an acceptable level, and the overall system is working as planned."
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Jenike & Johanson evaluated the feasibility of reliably handling the trona ore in two 1,300 ton capacity silos to be constructed underground. Flow properties tests on the trona confirmed what most operators knew: when stored at rest trona crystals grew together and formed a hard, solid mass. The tests provided the information necessary to design the silos for mass flow, which prevents stagnant, non-flowing regions where the trona could cake together. 