International Symposium on Uranium Raw Material for the Nuclear Fuel Cycle: Exploration, Mining, Production, Supply and Demand, Economics and Environmental Issues - IAEA CN-216

Uranium and REE recovery from acid mine drainage treatment waste – Caldas/BR case

Jun 25, 2014, 5:10 PM

VIC, Poster area (Vienna)

Poster Thorium and rare-earth element (REE)-associated resources Poster Session

Speaker

Mr Raul Sodré Villegas (Brazilian Nuclear Energy Comission)

Description

The Caldas uranium mine and mill was the first uranium producer site in Brazil. It has ceased its operations since 1995 and now it's under decommissioning process. One of the main issues to be dealt with is the acid water produced in some of the waste rock deposits due to the nature of the ore. As it is very known, the presence of sulfide containing minerals in the ore may promote the occurring of acid mine drainage (AMD), one of the main problems regarding environmental impacts of mining activities. To prevent contamination of the local watersheds, it is usual to treat the acid water produced with lime, to precipitate the soluble metals, and then store the solid produced in a safe way. This work aims to assess the uranium and rare earths recovery in the solid material produced at the Caldas site. It contains about 0,25% U3O8 and 2,5% RE2O3. The hydrometallurgical process being developed comprises leaching, solvent extraction and precipitation steps. Preliminary results of the acid leaching tests point to 96% and 90% recovery of U3O8 and RE2O3, respectively. The isotherm for uranium extraction shows a recovery of 99,7% of this element.