Brine과 bittern으로부터 Li, Mg 및 다른 유가금속 회수

다국어 초록 (Multilingual Abstract)

Lithium and its compounds have been used in variety of applications such as rechargeable batteries, glass and ceramic, aluminum, rubbers, pharmaceuticals or greases. Due to the widespread application, lithium production is required to meet the global demand. The production of
lithium from brine is about 2 times less expensive than minerals.
Locating in Bolivia’s highland, Salar de Uyuni is known to have the richest lithium resources in the world (of 10.2 Mt). A high Mg to Li ratio of 21.2 is a significant factor hindering the lithium production in Uyuni brine. Mg removal from brine is required in order to prepare for Li production.
Three reagents namely sodium hydroxide, sodium phosphate and oxalic acid were used for the test-work. Oxalic acid showed its efficiency in Mg removal from brine. The effect of pH and the amount of oxalic acid added were also studied in order to selectively removal Ca and optimize the subsequent Mg removal yield. At an addition of oxalic acid at oxalate:Ca molar ratio of 6.8:1 and pH<1, about 80% of Ca could be removed from the brine without co-precipitation of magnesium oxalate. A molar ratio of 1:1 to 1.6:1 oxalate:Mg in the pH range of 3 5.5 was used for ？ Mg precipitation as oxalate with the amount of NaOH addition for pH adjustment according to molar ratio of 1.95:1？3.2:1 NaOH:Mg. A recovery of >95% Mg was achieved (precipitate containing both magnesium hydroxide and magnesium oxalate), along with the loss of ∼30% Li
and 30% K in this stage. The NaOH addition used for pH
adjustment is the main reason causing the formation of Mg(OH)2.
Washing tests were conducted for the removal of impurities such as sodium chloride, sodium sulphate, carnalite etc. The XRD pattern shows a highly efficient removal of sodium chloride, sodium sulphate, carnalite as well as the high purity of >99% Mg oxalate yielded.
Weight reduction of 24.5-24.7% for pure product b and c in the first step and 46.6-47.1% in the 2nd step were obtained by DTA from MgC2O4.2H2O during roasting. Compared to pure MgC2O4.2H2O these weight losses would correspond to the removal of water (24.27% weight lost) at 220oC and conversion at 500oC to MgO (48.55% weight lost).

목차 (Table of Contents)

• 1. INTRODUCTION 1
• 2. LITERATURE SURVEY 4
• 2.1. Resources of magnesium-lithium 4
• 2.1.1. Resources of magnesium 4
• 2.1.2. Resources of lithium 6
• 2.2. Recovery technology 16
• 2.2.1. Recovery of magnesium 16
• 2.2.2. Recovery of lithium 22
• 2.3. Chemical speciation modeling - STABCAL software 28
• 3. EXPERIMENTAL PROCEDURES 31
• 3.1. Materials 31
• 3.1.1. Brine 31
• 3.1.2. Chemicals 31
• 3.2. Techniques 32
• 3.2.1. Equipment 32
• 3.2.2. Experimental 35
• 4. HYDROXIDE PRECIPITATION OF Ca-Mg PROCESS 39
• 5. PHOSPHATE PRECIPITATION OF Ca-Mg PROCESS 48
• 6. OXALIC ACID PRECIPITATION OF Ca-Mg PROCESS 53
• 6.1. The Ca removal - the 1st stage 54
• 6.2. The Mg removal - the 2nd stage 60
• 7. LITHIUM CARBONATE PRODUCTION 74
• 8. CONCLUSIONS AND RECOMMENDATIONS FOR FUTURE WORK 81
• REFERENCES 84