Аңдатпа
The present work presents the results of investigations into the composition of lithium-bearing rare-metal tailings and the development of methods for their processing. The treatment of rare-metal tailings for lithium recovery, considering that lithium is one of the most strategically important and highly demanded materials, represents a relevant and high-priority research area. The composition of the tailings was investigated using a range of physicochemical characterization techniques. The major mineral phases were identified as albite (Na[AlSi 3 O 8 ]), muscovite (KAl 2 [AlSi 3 O 10 ](OH) 2 ), quartz (SiO 2 ), microcline (K[AlSi 3 O 8 ]), and biotite (K(Mg,Fe 2+ ) 3 (Si 3 Al)О 10 (OH,F) 2 ). Lithium is predominantly present as an impurity and in isomorphically substituted forms within the crystal structures of muscovite and biotite. Among the lithium-bearing minerals, spodumene (LiAl[Si 2 O 6 ]) and lepidolite (KLi 2 Al[(AlSi) 4 O 10 ](F,OH) 2 ) were identified. Two sulfuric acid processing routes were investigated: with and without preliminary roasting of the tailings. The experimental results demonstrated that direct sulfuric acid treatment without prior roasting is the more effective approach. Direct sulfation of the tailings using 93 wt.% H 2 SO 4 at 300°C, with a solid-to-liquid ratio of 6-10:1 and a reaction time of 1-2 h, followed by water leaching at 90-98°C with a solid-to-liquid ratio of 1:6-10 for 1-2 h, enabled lithium extraction into the aqueous solution of approximately 72-98%. Lithium was subsequently recovered from the obtained lithium-bearing leach solution by chemisorption onto freshly precipitated aluminum hydroxide. The sorbent was synthesized using the aluminum already present in the solution as the major impurity, with the addition of ammonium hydroxide, which enabled the recovery of 99.78% of lithium from the solution into the sorbent phase. The distribution and separation coefficients for the chemisorption process were calculated for lithium, magnesium, and aluminum. The distribution coefficient for lithium was K d (Li) = 31,840, indicating a high degree of lithium uptake by the freshly precipitated sorbent and high selectivity. The separation coefficients of lithium from magnesium and calcium were Ks(Li/Mg) = 190–439 and K s (Li/Ca) = 56–135, respectively, demonstrating the potential for effective separation of lithium from most of the accompanying impurities.