The use of mica schist from Indonesia as raw material for lithium extraction process using sulfate roasting and acid leaching

Abstract

Lithium minerals become a sub-economic raw material for lithium production to fulfill the lithium demand. This study is about lithium extraction from mica schist using the roasting and leaching processes. The mica schist located in Kebumen, Indonesia was used to study the phenomena during the lithium extraction process. Sodium sulfate was used as a roasting agent while 0.36 M sulfuric acid was used as a leaching agent. Solid/liquid ratio (1:5, 1:10, 1:15 and 1:20 (g/mL)) and leaching time (30, 60, 90 and 120 minutes) were used as variables in this study. The roasting process was done at 700 °С for 40 minutes while the leaching process was done at 70 °С and 350 rpm. The ratio of additive and mica schist was 1.5:1 (g/g). XRD, ICP-OES, and SEM were used to observe the formed compounds, chemical composition and morphology of the materials. HighScore Plus (HSP) was used to interpret the content of each compound in mica schist, roasted mica schist, and residue. ICP analysis confirmed that the mica schist contains 45.28 ppm of lithium. It is supported by XRD that lithium exists in mica schist as lepidolite (KLi2AlSi4O10(F,OH)2). Sulfate roasting did not affect the type of lepidolite but the lepidolite reactivity against the chemical agent. SEM analysis shows that the roasting process reduced the average particle size from 32.17 to 27.16 µm. ICP analysis of roasted mica schist shows that lithium concentration was reduced from 45.28 to 1.27 ppm. The optimum result from this study was 97.66 % extraction of lithium while solid/liquid ratio was 1:5 (g/ml) and leaching time was 30 minutes. HSP shows that lepidolite contents in initial mica schist, roasted mica schist and residue were 60.6; 24.3 and 18.7 %, respectively. Lithium concentration in the residue according to ICP analysis is 1.06 ppm.

Using the gold bullion slag from Indonesia as lithium resources with HCL leaching method

“…Among all elements, Si (21.87 %) and O (43.58 %) dominate the morphological structure of the sample while the minor elements in gold bullion slag are Zn (3 %), Cr (0,92 %) and Mg (1.5 %). This result shows that gold bullion slag has a similar composition with mica schist in Indonesia such as Al, Fe, Si, Ca, Na and Mg [19].…”

“…It shows that low temperature can use with attention to other variables that have significant effects because higher temperature will impact to the loss lithium. It can happen because the high pressure (100 kPa) at 70 °C will give a higher specific volume of saturated liquid and saturated vapor [19]. In consequence, a lot of elements, including lithium, could vaporize.…”