Sedimentation method of spodumene
First, the 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, but also for the production of hand-selected lepidolite, petalite, lithium phosphate, lithium aluminum ore stone.
United States South Dakota Black Hills region is the first US lithium mining mining area, has used hand-selected method selected spodumene concentrates from pegmatite ore, sometimes it comes to recover some of feldspar minerals and heavy metals. The first deposit in the Black Mountain area contains Li 2 O 1.5% to 1.7%. The ore is mainly composed of spodumene, quartz , micro-plagioclase, albite, muscovite, apatite and tourmaline . In 1948, a hand-selected method was used to select a spodumene concentrate with a yield of 10.5%, with a grade of 4.8% Li 2 O, and a recovery rate of 30% to 40%. Due to low economic efficiency, the plant reformed the process in 1949. The 3.3-38 mm grain grade was changed to heavy medium beneficiation, and the 38-300 mm grain grade ore was still selected by hand to remove waste rock.
In the 1950s, China’s No. 1 Mine and No. 3 Mines had been producing the spodumene concentrate by hand. The ore contained 1.5% to 1.8% Li 2 O, and the hand-selected concentrate grade was 5% to 6% Li 2 O. The recovery rate was 20 %~30%.
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.
Figure 1 shows the principle flow of the granitic pegmatite lithium mine.
Figure 1 Granite pegmatite lithium mine hand selection principle process
Second, the flotation method
There are two different processes for spodumene flotation: one is positive flotation and the other is reverse flotation.
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, adding high concentration, strong agitation and multiple washing and de-muding, adding The fatty acid or its soap is used as a collector to directly float the spodumene.
The Soviet Union Mineral Processing Research Institute has conducted a beneficiation study on the Zaviqin deposit, which is a pegmatite deposit. The sample is taken from the coarse-grained zone and partially weathered. The spodumene grains are mostly 10-15 mm. The proposed process developed by the institute is a positive flotation process, as shown in Figure 2. According to this process, the mine can obtain a spodumene concentrate with a grade of more than 5% Li 2 O, and the recovery rate is 70% to 75%.
Figure 2 The Soviet Union's proposal for the treatment of the Zaviqin mine
As early as 1960, when the beneficiation study was carried out on the pegmatite spodumene ore in Xinjiang, China's ore dressing workers first invented and formulated a simplified process for the alkaline flotation process without sludge removal and non-washing. As shown in Figure 3. The process was used in production in 1961. The industrial production index is: 1.3% to 2% Li 2 O in the ore, and the diaspresite concentrate grade is 4% to 5% Li 2 O, and the recovery rate is 85% to 90%.
Figure 3 Sparkling process of spodumene alkali flotation
The reverse flotation process is to inhibit the spodumene in a lime-adjusted alkaline medium with dextrin and starch as a regulator, and use a cationic collector to float the silicate-like gangue mineral as a foam. The product in the tank is The spodumene concentrate, shown in Figure 4, is the reverse flotation process recommended by Denver.
In the 1950s and 1960s, the United States adopted a reverse flotation process. Currently, both the US and China's spodumene flotation plants use a positive flotation process.
Figure 4 Denver's recommended reverse flotation process
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