4171 results about "Yield rate" patented technology

The invention relates to a method for preparing lithium carbonate by extracting lithium from lepidolite. The method comprises the following steps of: a. calcination and defluorination at a high temperature; b. grinding; c. autoclaving; d. impurity removal; e. condensation; f. sodium separation by freezing; g. ithium precipitation by carbonization, wherein, in the step c, the grinded lepidolite, calcium oxide and sodium salt are thrown into a high-pressure kettle for autoclaving; the lepidolite is decomposed in the continuous stirring state; and alkali metal in the lepidolite is subject to ion exchange, turned into salt and dissolved out. In the step d, an autoclaving mother solution and autoclaving residues are obtained after separation and autoclaving; sodium hudroxide with slightly excess amount according to the Lithia content in the autoclaving mother solution is added and evenly stirred, then activated carbon is added for filtering and impurity removal. In the step g, CO2 is led to a sodium separation mother solution till the PH value of the solution is equal to between 9 and 10; the mother solution is heated, stirred, carbonized and subject to centrifugal water spinning and separation to obtain coarse lithium carbonate; backwashing and drying are carried out to the coarse lithium carbonate, thereby obtaining a product of lithium carbonate. The method has the advantages that: the method has high lithium yield rate; residues can be utilized; and sodium salt can be recycled, etc.