Recovering Lithium from Clays· PRU Equipment Feed for the roast was ground and mixed in a ball mill 16 in diam by 24 in length The minus 100 mesh mixture was pelletized with water in a 20 in diam drum pelletizer fig 12 The pellets were roasted in a direct fired rotary roaster fig 15 that was fired with natural gas and had a working capacity of ft³ The roast