102 samples of low-grade uranium ore from 70 drill holes at Kvanefjeld, Ilimaussaq alkaline intrusion, South Greenland were studied by means of autoradiography, fission-track investigations, microscopy, microprobe analyses and uraniumleaching experiments. The principal U-Th bearing mineral steenstrupine, and several less common uranium minerals are disseminated in lujavrite 'nepheline syenite) and altered volcanic rocks. Stenstrupine has average composition Na6.7HxCa1.0(REE+Y)5.8(th,(t)0.5 (Mn1.6Fe1.8Zr0.3Ti0.1Al0.2) Si12O36 (P4.3Si1.7)O24 (F,OH) • nH2O n and x are variable. It either is of magmatic origin (type A) or connected with metasomatic processes (type B), or occurs in late veins (Type C). Preponderance of grains are metamict (usually 2000-5000 ppm U3O8 or altered (usually above 5000 ppm U3O8), sometimes zoned with both components present. Occasionally they are extremely altered with U content falling to 500-5000 ppm U3O8 and local accumulations of high-U minerals formed. Replacement by crystalline monazite (± metamict uranothorite and other components) is locally important. Uranium recovery by carbonate leaching (NaHCO3+Na2CO3+O2) depends both on alteration of steenstrupine and on hydration of parent rocks. Yield is between 98 and 50%, the average U concentration in the examined rock around 350 ppm U.
|Place of Publication||Roskilde|
|Publisher||Risø National Laboratory|
|Number of pages||184|
|Publication status||Published - 1980|
|Series||Denmark. Forskningscenter Risoe. Risoe-R|