Mineralogy and uranium leaching of ores from Triassic Peribaltic sandstones

Abstract

The recovery of uranium and other valuable metals from Polish Peribaltic sandstones were examined. The solid-liquid extraction is the first stage of the technology of uranium production and it is crucial for the next stages of processing. In the laboratory experiments uranium was leached with efficiencies 71-100 % by acidic lixiviants. Satisfactory results were obtained for the alkaline leaching process. Almost 100 % of uranium was leached with alkaline carbonate solution. In post leaching solutions only uranium and small amounts of vanadium were present.

Keywords: Acid leaching; Alkaline leaching; Sandstones; Uranium.

Fig. 1

Uranium mineralization in the form of rhomboedric crystals (probably coffinite) in the highly porous sandstones with carbonate cement

Fig. 2

Uranium mineralization fills spaces between micas crystals

Fig. 3

Minimal and maximal values of efficiencies of leaching of metals from sandstones deriving from Peribaltic Syneclise (samples from different boreholes, min: sample 21/10/160, max: sample 21/10/140, see Table 2) under different process conditions: a 10 % HCl, 30 % H₂O₂, 60 °C, 1 h, agitation rate: 500 rpm; b 10 % H₂SO₄, MnO₂, 60 °C, 1 h, agitation rate: 500 rpm

Fig. 4

Effect of sulphuric acid concentration on leaching efficiency (sample 21/10/160). Process conditions: particle size: 0–0.2 mm, liquid/solid ratio of 8:1 (vol./wt. basis), oxidizing agent MnO₂, 60 °C, 1 h, agitation rate: 500 rpm

Fig. 5

Effect of hydrochloric acid concentration on leaching efficiency (sample 21/10/160). Process conditions: particle size: 0–0.2 mm, liquid/solid ratio of 8:1 (vol./wt. basis), oxidizing agent: H₂O₂, 60 °C, 1 h, agitation rate: 500 rpm

Fig. 6

Minimal and maximal values of efficiency of leaching of metals from sandstones deriving from Peribaltic Syneclise (samples from different boreholes, min: sample 21/10/160, max: sample 21/10/140, see Table 2) under different process conditions: a 8 % NaOH/18 % Na₂CO₃, 30 % H₂O₂, 60 °C, 1 h, agitation rate: 500 rpm, b 5 % Na₂CO₃/NaHCO₃, KMnO₄, 60 °C, 1 h, agitation rate: 500 rpm

Fig. 7

Effect of time on uranium leaching efficiency (sample 21/10/140). Process conditions: particle size: 0–0.2 mm, liquid/solid ratio of 8:1 (vol./wt. basis), 60 °C, agitation rate: 500 rpm, lixiviants: a 10 % HCl b 10 % H₂SO₄, c 8 % NaOH/18 % Na₂CO₃ d 5 % Na₂CO₃/NaHCO₃

Fig. 8

Effect of temperature on leaching efficiency (sample 21/10/166). Process conditions: particle size: 0–0.2 mm, 10 % H₂SO₄, liquid/solid ratio of 8:1 (vol./wt. basis), oxidizing agent: MnO₂, 1 h, agitation rate: 500 rpm

Fig. 9

Effect of liquid/solid ratio (vol./wt. basis) on uranium leaching efficiency (sample 21/10/141). Process conditions: particle size: 0–0.2 mm,10 % H₂SO₄, oxidizing agent: MnO₂, 60 °C,1 h, agitation rate: 500 rpm

Fig. 10

Effect of particle size on uranium leaching efficiency (sample 21/10/161). Process conditions: 10 % H₂SO₄, MnO₂, liquid/solid ratio of 8:1 (vol./wt. basis), 60 °C, 1 h, agitation rate: 500 rpm

Fig. 11

Effect of oxidizing agent on uranium leaching efficiency (sample 21/10/169). Process conditions: a particle size: 0–0.2 mm, 60 °C, 1 h, agitation rate: 500 rpm, b particle size: 0–0.2 mm, 60 °C, 1 h, agitation rate: 500 rpm

Fig. 12

Effect of concentration of iron in ore on uranium leaching efficiency. Process conditions: particle size: 0–0.2 mm, 10 % H₂SO₄, liquid/solid ratio of 8:1 (vol./wt. basis), 60 °C, 1 h, agitation rate: 500 rpm

Fig. 13

Metal extraction behavior with distilled water and oxidants. Process conditions: particle size: 0–0.2 mm, liquid/solid ratio of 8:1 (vol./wt. basis), 60 °C, 1 h, agitation rate: 500 rpm

Fig. 14

Metal extraction behavior with 10 % NH₄Cl/H₂O₂ and HNO₃, pH 3, without oxidants. Process conditions: particle size: 0–0.2 mm, liquid/solid ratio of 8:1 (vol./wt. basis), 60 °C, 1 h, agitation rate: 500 rpm