Mineralogy And Lithium Extraction Technology Study Of Spodumene From Caijiagou In Lushi, Henan Province

Because of its unique properties, lithium, in the form of inorganic compounds, organic compounds, metals and their alloys, is widely used in various fields. Currently, the exploitative and available lithium resources used for lithium production are main- ly lithium pegmatite deposits and lithium brine deposits, while spodumene of the lithium pegmatite mines is the most widely used mineral, followed by the lepidolite and petalite.The mineralogy of spodumene from Caijiagou in Lushi Country, Henan Province were entirely studied through a variety of modern testing techniques.And a systematic understanding of mineralogical characteristics of spodumene were formed in this ore- field. According to hand specimen and microscopic observation, spodumene from Caijiagou commonly occurred as idiomorphic—subhedral crystals in the pegmatite, in the form of columnar and tabular, with the color of white, gray, light green, and there was the phenomenon of a small amount of alteration. The main mineral compositions of spodumene-bearing granitic pegmatites were spodumene, quartz, albite, microcline and muscovite and so. According to X-ray fluorescence and ICP-MS analysis, the chemical compositions(in percent) of spodumene were SiO₂ 64.23, Al₂O₃ 26.77, Na₂O 0.84, K₂O 0.83, FeO 0.54, CaO 0.24, MgO 0.22, MnO 0.11, Li₂O 4.26, Rb₂O 0.035, Cs₂O 0.020;The analysis of trace elements showed there were negative abnormal phenomena of Eu and Ce to a certain degree in the REE distribution of spodumene by analyzing chondrite-normalized REE patterns of spodumene from Caijiagou. The negative Eu anomaly showed that spodumene was crystallized later than plagioclase in the process of magmatic differentiation(Pegmatite formation). The negative Ce anomaly showed that oxygen fugacity of the melt-solution which formed pegmatitethe was high. The lattice parameters of spodumene was a=9.477(A|。), b=8.413(A|。), c=5.225(A|。),β=110.060°by analyzing X-ray powder diffraction data of samples.Infrared adsorption spectroscopic data of samples showed the characteristic wave numbers of spodumene were 468, 538, 591, 633, 861, 925, 1020 and 1086cm^-1 in the range of 400¹600cm^-1. Then sodium carbonate calcination, a kind of lithium extraction technology, was used in the spodumene from this orefield. And the experimental process was refined and improved, expected to be an efficient, low-cost method of extraction of lithium, in order to provide some fixed theoretical bases and experimental data for the rational development of lithium ore in Caijiagou. In the experiment, firstly the spodumene powder mixed with a certain percentage of sodium carbonate was roasted,subsequent- ly lithium in the spodumene turned into the soluble Li⁺; Through adding concentrated hydrochloric acid, sodium hydroxide into the new product in proper order, silicon and aluminum were removed.Finally by adding sufficient sodium carbonate,lithium carbo- nate was obtained through evaporation of the solvent at the constant temperature and repeated filtering and washing, then drying. The XRF testing showed that extraction rate of silicon was 90.98% and extraction rate of aluminum was 90.97% in the experi- ment.DTA and TG analysis showed spodumene directly mixed with sodium carbonate with the mass ratio of 1.04:1 at 799⁸45℃had great weight loss rate. Whenα-spodu- mene changed intoβ-spodumene, spodumene reacted with sodium carbonate into a soluble lithium salt. This method, which simplified the roasting steps and reduced the cost of production, was feasible.