Depth-induced deviation of column bioleaching for uranium embedded in granite porphyry by defined mixed acidophilic bacteria

Sulfur enhancement effects for uranium bioleaching in column reactors from a refractory uranium ore

“…The possible reasons for this phenomenon were as follows: firstly, the lower layer contained less oxygen than the upper layer and it endured greater pressure. These might inhibit the bacterial growth and activities (Yang et al, 2022 ). Moreover, bacteria turned into the decline stage at the bottom of the column reactors due to lack of nutrients in the late-bioleaching phase.…”

“…As can been seen in Table 2 , the elements Al, Na and Mn were dissolved into the leach liquor simultaneously, resulting in a decrease of the content in the leaching residues. The content of Ca, Fe and K on the residue surface was 2–3 times that of the raw ore. We infer that jarosite as the passivation layer was formed on the surface of the residues (Tuovinen and Bhatti, 1999 ; Yang et al, 2022 ). As the upper layer had higher uranium extraction, the passivation layer was most likely formed in the lower layer of the column reactors.…”

“…The adsorption columns were 70 cm high with an internal diameter of 1 cm and connected to each reaction column. The column leaching experiments included two phases, acidic pre-leaching and microbial leaching (Yang et al, 2022 ). The column leaching turned into bioleaching phase when pH of the leaching liquor was at approx.…”