Recovery of lithium compounds from brines
Methods and apparatus for the production of low sodium lithium carbonate and lithium chloride from a brine concentrated to about 6.0 wt % lithium are disclosed. Methods and apparatus for direct recovery of technical grade lithium chloride from the concentrated brine are also disclosed.
1. An apparatus for continuously purifying lithium carbonate comprising:
a dissolver which is a baffled reactor to dissolve lithium carbonate that includes a mixer/disperser,
a carbon dioxide gas dispersion tube,
a wash water filtrate/mother liquor filtrate recycle line,
a cooler,
a stilling well to separate gas and undissolved lithium carbonate solids from the resultant lithium bicarbonate solution, and
a continuous chemical grade lithium carbonate crystal feeder;
an inline filter to remove insoluble impurities from the lithium bicarbonate solution coming from the stilling well;
a heat exchanger to recover heat from the hot mother liquor that is recycled to the dissolver;
a heated gas sealed crystallizer with mixer to decompose the lithium bicarbonate solution to form low sodium lithium carbonate crystals, carbon dioxide gas, and mother liquor;
a slurry valve to remove the low sodium lithium carbonate crystals and mother liquor from the gas sealed crystallizer;
a gas line to continuously return the carbon dioxide produced in the crystallizer to the dissolver;
a separator such as a continuous belt filter to separate the low sodium lithium carbonate from the mother liquor and a wash water section to wash the lithium carbonate crystals;
a pump and line to return the mother liquor and wash filtrate to the dissolver;
a mother liquor bleed to control the sodium level and to maintain a constant liquid volume;
a carbon dioxide make up source.
2. The apparatus of claim 1 , comprising a reactor using absorption columns, such as a sieve tray or a Scheibel column, to facilitate absorption of carbon dioxide.