Lithium is an important strategic resource widely used in emerging fields such as batteries, ceramics, glass, aluminum , lubricants, refrigerants, nuclear industry and optoelectronics. It is an indispensable and important raw material for modern high-tech products.
1. Distribution of lithium ore
By the end of 2008, the country has identified lithium ore mining (mostly lithium, beryllium, niobium, tantalum comprehensive endogenous deposits) at 42, proved reserves (equivalent to, the same below) 2.4121 million tons, of which the foundation reserves 101.78 10,000 tons (including reserves of 815,500 tons), distributed in 9 provinces and autonomous regions, of which the proportion of resource reserves () in the country's total resource reserves ranked in the order of: Sichuan accounted for 52.8%, Jiangxi accounted for 24.1%, Hunan accounted for 15.0%, Guizhou 2.9%. Xinjiang was originally a large province of ore lithium resources. However, due to the large-scale mining of the main mining area for more than 40 years, the reserves have been greatly reduced, and the reserves of reserves only accounted for 2.4% of the country. The above five provinces and autonomous regions accounted for 97.2% of the total. The identified x-masons mining area has 6 sites, with a reserve of 54,900 tons of resources, of which the basic reserves are 22,400 tons, accounting for 40.8%. It is distributed in 3 provinces and regions, of which Jiangxi accounts for 53.0% and Xinjiang for 45.5%.
Second, the development prospects
From the perspective of the changes in the various uses of lithium in recent years, lithium has become the first largest application field in terms of the growth rate of lithium in other fields. At present, the global demand for lithium carbonate is around 140,000 tons. It is expected that the global demand for lithium carbonate will maintain an average annual growth rate of 15% to 20%, driven by the growth in demand for global consumer electronics and new energy vehicles. The annual consumption will reach more than 300,000 tons, and the proportion of new energy vehicles to lithium carbonate will increase from 9.7% in 2012 to 37.8% in 2017.
If the global new energy vehicles, especially the pure electric vehicles represented by the US Tesla, grow faster, the global demand for lithium carbonate will reach 260,000 tons by 2016. As for the supply of lithium carbonate, there will be a gap in the supply and demand of global lithium carbonate by 2016.
Third, lithium ore dressing equipment
The lithium ore beneficiation equipment produced by Yankuang Machinery has crushers , ball mills , jigs, flotation machines, etc., as well as some auxiliary equipment to form a complete production line.
Fourth, lithium ore beneficiation method
(1) Hand selection method
The hand selection method is a sorting method based on the difference in color and appearance between lithium minerals and gangue minerals. The selection granularity is generally 10 to 25 mm, and the determination of the lower limit of the particle size depends on economic benefits. Hand selection is the earliest method of mineral processing used in the history of lithium mine production. The United States used this method to produce spodumene concentrate from the pegmatite deposit in the Black Mountain area of ​​South Dakota as early as 1906. In addition to spodumene, the hand is also used to produce lithium concentrates such as lithium mica , lithium feldspar , and lithium phosphite .
Granite pegmatite lithium mine hand selection principle process
The hand selection method has been generally replaced by flotation or other methods due to its high labor intensity, low production efficiency, poor beneficiation index and large waste of resources. However, in areas where labor is cheap, hand selection is still a kind of coarse-buried lithium ore. An important method for producing lithium concentrate.
(2) Flotation method
There are two different processes for spodumene flotation: one is positive flotation and the other is reverse flotation.
1 The positive flotation process is the process of preferential flotation of spodumene. The essence of the process is: grinding the ore in an alkaline medium formed by sodium hydroxide or sodium carbonate, after high concentration, strong stirring and multiple washing and de-sludge, The fatty acid or its soap is added as a collector to directly float the spodumene.
2 The reverse flotation process is to inhibit the spodumene in a lime-adjusted alkaline medium with a dextrin and a starch-based modifier, and use a cationic collector to float the silicate-like gangue mineral as a foam, and the product in the tank is It is a spodumene concentrate.
Hand selection and flotation are the main methods for selecting spodumene. Other methods such as thermal cracking, magnetic separation and re-election play an auxiliary and secondary role in the production of spodumene concentrate.
(3) Thermal cracking ore dressing method
The thermal cracking beneficiation method is a method of selecting a spodumene ore. The method is based on the natural spodumene calcination at about 1100 ° C, the crystal changes from α type to β type, while volume expansion, brittle into powder, which can be used to selectively grind and sieve to reach spodumene and gangue Separation of minerals. This method has been applied in the Canadian plant, China, and the Soviet test room. China's ore dressing workers have used raw ore containing 1.58% Li3O for testing. They were first calcined at 1050 °C for one hour, cooled and placed in a rubber ball mill for selective grinding. Finally, they were sieved with a 150 mesh sieve. The sieve concentrate has a grade of 4.9% Li2O and a recovery of 74%.
There are two points to note when applying the thermal cracking method:
1 The calcination temperature is controlled at 1100 ° C. When the temperature is too high, the mica present in the ore will be sintered; when the temperature is too low, the transformation of spodumene from α to β is incomplete.
2 The ore should not contain a large amount of minerals that are easily melted during calcination or other minerals with thermal cracking properties, otherwise the purpose of separating spodumene may not be achieved.
(4) Heavy medium beneficiation method
Since the difference in density between spodumene and associated gangue minerals is not large, re-election methods such as jigging, spiral beneficiation and shaker beneficiation are not suitable for the selection of spodumene ore. However, heavy medium ore dressing or heavy liquid beneficiation is an effective method for semenite ore. Heavy medium dressing has been used in the production of lithium mines in South Dakota and North Carolina. In South Dakota were prepared in a processing plant -200 mesh silicon iron weighting agent and the density was 2.7 g / cm 3 medium, heavy medium using a cone concentrator sorting plant of 3.3 to 3.8 mm spodumene ore, As a result, the produced spodumene concentrate grade reached a 5.31% Li2O operation recovery rate of 78%. In North Carolina Gold Mine wire except heavy medium beneficiation machine taper, used heavy medium cyclone sorting finer size range spodumene. Further U.S. Bureau of Mines with further beneficiation art tetrabromo ethane as the heavy liquid (density of 2.9529 g / cm 3) of the heavy liquid cyclone sorting of successive trials spodumene ore, quite satisfactory results are achieved, the feed size For -35 mesh, containing 20% ​​of lithium phosgene, the obtained concentrate contains 92~95% of lithium pyroxene, the recovery rate is 86~89%, and the recovery rate of heavy liquid is above 95%. As long as there is good protection, Tetrabromoethane can be used on a large scale.
(5) Magnetic separation method
Magnetic separation is often used as an auxiliary method to improve the concentrate quality of spodumene. For example, the spodumene concentrate produced by the flotation of the Jinsishan plant in North Carolina, USA, is high in iron and can only be sold as a chemical grade concentrate. In order to meet the requirements of the ceramic industry, the plant uses magnetic separation to remove iron. In addition, since iron-lithium mica has weak magnetic properties, magnetic separation can be used as the main method for producing iron-lithium mica concentrate.
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