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There are five main types of lithium deposits in the world, namely pegmatite deposits, brine deposits, seawater deposits, hot spring deposits and accumulation deposits. Currently, lithium resources mined and utilized are mainly pegmatite deposits and brine deposits, and brine deposits account for 90% of proven resources.
The mineral raw materials for producing lithium are mainly spodumene, lepidolite, lithium-permeticite, petalite and iron lepidolite, among which the first three minerals are the most important. Lithium ore beneficiation methods include hand selection, flotation, chemical treatment, heavy suspension liquid beneficiation, heavy liquid beneficiation, and thermal cracking beneficiation, among which the first three methods are more commonly used.
This method is mainly used for the separation of spodumene and lepidolite combined with coarse grain crystals. It is based on the difference between the color or shape of the mineral itself and the gangue mineral. The lithium mineral is selected from the mineral by manual hand selection, and the selective grinding Compared with the hand selection method, it was the main beneficiation method of lithium ore before 1940-1941.
The main minerals containing lithium can be sorted by flotation, so flotation is an important beneficiation method for lithium ore, especially for fine-grained disseminated spodumene beneficiation, it is even more important. Spodumene is commonly used as an organic collector, which is easier to float in neutral and alkaline media. At this time, its regulators are mostly sodium carbonate and sodium hydroxide, and sodium fluoride and lignosulfonate are also used as regulators. Because of its special oreological properties, the flotation particle size is more important. When the particle size is 0.2mm, the flotation recovery rate is 61%, and when the particle size is 0.3, the flotation recovery rate is 22%.
The lithium ore positive flotation method refers to adding a strong alkali flotation after the lithium ore is ground (try to avoid over-grinding to cause muddy phenomenon). After high concentration in alkaline medium, strong stirring, and repeated scrubbing to remove mud, add oleic acid and soap salts as collectors to directly float lithium concentrate, leaving gangue minerals in the tank. This process does not need to be added Inhibitors.
The lithium ore reverse flotation method refers to creating an alkaline environment with the help of lime, adding starch, dextrin, etc. to inhibit the lithium ore from floating up, and at the same time using a cationic collector to float the silicate gangue minerals to the surface of the pulp, and the products in the flotation machine tank It is lithium concentrate. If lithium ore contains iron minerals, foaming agents (such as HF, resinate) can be added to further help remove impurities such as iron minerals.
Chemical treatment methods are mainly used to extract lithium from salt lake water. First, the salt lake water is evaporated on an area of nearly 405 hectares. After evaporation, the concentration of lithium chloride can reach 6%. During the evaporation process, sodium and potassium salts are precipitated from the brine, and the remaining lithium-containing solution is brine. The bittern is introduced into the factory, and the lithium chloride is converted into solid lithium carbonate by the soda ash method.
The relative density of spodumene is about 3.2, which is higher than the density of main gangue minerals such as quartz and feldspar that often coexist with spodumene. In this way, resuspension liquid beneficiation method can be used to make spodumene a heavy mineral product , while gangue minerals are light products.
This method is to heat the spodumene ore to 1000-1200°C. After heating, the crystal form of the spodumene changes, and the relative density changes to 2.40, and becomes a brittle and fragile ore. However, at this time, the gangue such as quartz is There is not much change, and then the selective grinding method is used to make the spodumene into powder, and the gangue such as quartz that is not easy to grind is still relatively thick, and then it is separated by screening or wind beneficiation. This method can enrich spodumene raw ore containing 0.8%-2.0% lithium dioxide to lithium concentrate containing 4%-6% lithium dioxide, and the recovery rate is 70%-80%. However, this method has certain limitations in practical application due to the high temperature required for roasting and the inability to comprehensively recover other useful metal components.
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