U price up to 33 month high, page-98

Another interesting snippet from the paper mentioned above.

Nine MileLake/Casper, Wyoming - Sulphuric Acid ISL on Trial

Rock Mountain Energy Co., in conjunction inwith US Bureau of Mines, conducted a pilot-scale In Situ Leaching experimentnear Casper, Wyoming, of sulphuric acid leaching chemistry, summarised in greatdetail in Nigbor et al., 1981and Nigbor et al., 1982. Theprincipal aim was to determine if there were any cost advantages in using suchlixiviants over the more conventional alkaline agents used principally in Texasand at other sites in Wyoming. The trial showed that while sulphuric acid isindeed an effective lixiviant, there were no overall cost advantages, and manyenvironmental problems became evident also. 

Nine MileLake/Casper – Summary 

It is not known whether this site wasupgraded to a commercial mine site. It would appear not, as it is not listed inany recent USDoE or USEPA literature. The ISL trial very clearly showed thatthere were many significant operational and environmental problems withsulphuric acid leaching chemistry. These include the mobilisation of extremelyhigh levels of radioactive thorium, the buildup of mineral precipitates (such asgypsum), the mobilisation and buildup of many trace elements during leachingandthe difficulties of groundwater qualityrestoration.