An Experimental Study On Sandstone-Type Uranium Ore At High Temperature And High Pressure

Ordos Basin is one of the greatest energy-mineral-deposits gathering basins in China. Ordos Basin is a suitable place for research on coexistence of multiple energy resource and coexisting mechanism. Dongsheng sandstone-type uranium deposit, the latest large deposit, is located in the northeast of the basin; however, there are some limits in the study that temperature, pressure and natural gas influence the dissolution of uranium. The experiments which performed in high temperature and high pressure in this study intend to find the different dissolving capacity of reducibility fluid at different temperature and pressure, and to examine the effect of CH4 on uranium dissolution.In this paper, the experimental instrument is liquid-flow reaction equipment and we conducted four group experiments of water-rock interaction modeling research in various temperatures and pressures, which include as followed: (1) Static experiment at 100℃, 20Mpa and deionized water from 1 day to 7 days; (2) Dynamic experiment at deionized water ,15MPa and 20MPa with the temperature form 50℃to 350℃; (3) Dynamic experiment at 150℃and 15MPa varying deionized water, acetic acid and brine with CH4; (4) Dynamic experiment at 100℃,1MPa,10MPa and HCl-NaCl water with CH4. Through the X ray diffraction and chemistry analysis, we catch the mineral records. And also we get the record of fluid through experiments on the multiparameter meters and ICP.Our preliminary results from the experiment on sandstone show that (1) The Ca/Mg ratios is stable, and it’s mean value equal to 5.91 at 20Mp and 100 oC, and this characteristic means that Ca/Mg ratios in the ?uid are a potential geothermometer. (2) Electrical conductivity increases with temperature at 20 MPa and deionized water with the temperature form 50℃to 300℃. Consistency of Si and K increases with temperature, especially at high temperature phase. (3) The dominant solution temperature of uranium is distinct in different pressures. It is 150℃at 20MPa, whereas it is 100℃at 15MPa. (4) Dissolving capacity of uranium in acetic acid is better than that in deionized water and brine, and dissolving capacity of uranium decreases with CH4 existence in acetic acid and deionized water. Reducibility gas contributes to the genesis-enrichment of Dongsheng sandstone-type uranium ore.