Lithium carbonate Drying: Equipment Selection

Battery grade lithium carbonate is sensitive on three fronts at once: moisture, impurities and particle size, which makes it one of the most demanding materials on the line. Our approach is a rotary drum rather than a flash unit, because lithium carbonate has a high bulk density and has to be taken below 0.3 percent moisture: the seconds-long heating of a flash dryer carries the fines around inside the duct and they cannot be graded out, whereas the flights in a drum keep the material tumbling with far more relative motion, so the residual moisture can be drawn out over a longer residence time at the tail end. The heat source is electric or electromagnetic, with no open flame.

Battery grade lithium carbonate is sensitive on three fronts at once: moisture, impurities and particle size, which makes it one of the most demanding materials on the line. If moisture is not held, the battery plant receives a rejected batch; if impurities are over, the precursor synthesis is affected; and if the particle size spreads, blending downstream is uneven. Our approach is a rotary drum rather than a flash unit, because lithium carbonate has a high bulk density and has to be taken below 0.3 percent moisture: the seconds-long heating of a flash dryer carries the fines around inside the duct and they cannot be graded out, whereas the flights in a drum keep the material tumbling with far more relative motion, so the residual moisture can be drawn out over a longer residence time at the tail end. The heat source is electric or electromagnetic, with no open flame, which removes the risk of a flame in a hydrogen atmosphere and keeps the drum wall below 150°C so the carbonate does not decompose. The moisture basis has to be written into the contract: dry basis and wet basis differ by thirty percent, so the quotation and the acceptance test are not the same number.

Should lithium carbonate be dried in a rotary drum or a flash airflow dryer?
Our standard is a rotary drum. Lithium carbonate has a high bulk density and has to reach below 0.3 percent moisture; the seconds-long heating of a flash dryer carries the fines around inside the duct and they cannot be graded out, whereas the flights in a drum keep the material tumbling with far more relative motion, so the residual moisture can be drawn out over a longer residence time at the tail end.

What temperature does lithium carbonate need?
There is no general figure; it is set by the grade. The principle is that the drum wall stays below 150°C so the carbonate does not decompose. The heat source is electric or electromagnetic, with no flame, which removes the risk of an open flame in a hydrogen atmosphere and makes the wall temperature easier to hold.

Why must the quotation state dry basis or wet basis?
Because the two bases differ by more than thirty percent. If the quotation is on a wet basis and the acceptance test on a dry basis, the difference is a whole machine. This has to go into the contract, not just the quotation.