This is the second in my “Know Your Business” series where I will discuss what a Roll Front Uranium Deposit is.
Basically, a roll front uranium deposit is found in a permeable and porous sandstone aquifer through which uranium bearing groundwater flows. The deposit bed or channel must be flat or gently dipping and sealed above and below by a non porous mudstone or shale layer. The channel must also be below the water table or in a confined aquifer. Roll front uranium deposits are the usually the best deposits for in-situ mining, which I will discuss in Part 3.
Roll fronts are formed when oxidized groundwater migrates through the porous sandstone aquifer carrying disolved uranium from a source rock location and re-deposits it as a reduced precipitate uraninite. This reduction and oxidation – redox process – is what creates the crescent shaped roll front ore body seen in the illustration and photo.
Sandstone deposits make up about 18% of the world’s uranium resources and are usually at a low to medium grade (0.05 – 0.4% U308) – I will explain grade in a later post. The deposits are usually small to medium size and the main method of mining them are through the in-situ recovery (ISR) mining method which is very economical.
Well, that’s it for Part 2. On to Part 3: In-Situ Recovery Uranium Mining!
Photo courtesy of Power Resources
References for this post:
Wyoming State Geological Survey – The Origin of Uranium Deposits
ICMJ’s Prospecting and Mining Journal – October 2003 – Roll Front Uranium Deposits – Edgar B. Heylmun, PhD
Wikipedia – Uranium
World Nuclear Association – January 2010 – Geology of Uranium Deposits
WMA Minelife – Uranium Roll Fronts