Study on extraction of lithium from clay-type lithium ore with low roasting temperature and water and its mechanism

In recent times, because of its vigorous development in the domain of new energy, especially the unique advantages of electric vehicles and energy storage batteries, lithium resources have made their application scale explosively growing. It is of great strategic impact to fully develop the existing lithium resources. In this paper, a low-temperature calcination with ammonium persulfate and water extraction test was conducted for the exploitation of clay-type lithium ore in the central region of Yunnan, China, and a novel green extraction method of Li with low energy consumption was proposed. The results of the test indicated that under the factors of calcination temperature of 400 degrees C, ammonium persulfate dosage of 50 %, calcination time of 1.0 h, extraction temperature of 75 degrees C, extraction time of 1.0 h and water and ore ratio of 4:1, the extraction rate of lithium could reach 80.10 %. The temperature was obviously lower than other reports. The reaction mechanism of the calcination procedure was explored by means of SEM, XRD, XPS and TG-DSC. The test outcomes indicated that after roasting, the mineral morphology changed significantly, and the ore particles were agglomerated and the structure was molten. Chemical reaction occurred during the calcination procedure, and the phase of the main mineral in the sample changed obviously. All of chlorite (lithium-bearing mineral), and partial of kaolinite, and diaspore (boehmite) changed to godovikovite, millosevichite, and tschermigite, which had high solubility in water. Thus, the roasting with ammonium persulfate facilitated the dissociation of lithium and strengthened the water leaching. The extraction process was mainly a process of mineral dissolution.