Abstract: Following the work on gas lift reactor (Pachuca tank) for gas-liquid-suspended solid 3-phase reaction, multideck gas lift reactors have been developed. This type of reactor has many unique advantages such as achieving of counter-current operation between gas and slurry, decreasing of gas consumption and small amount of volatile component of liquid required to recovery from the exit gas. The stability of the overflow tube of the reactor was studied. Semi-empirical equation was derived to calculate the flooding point of the reactor. The operating range of the overflow tube was also determined. This multideck reactor has been operated successfully in a pilot plant of ammonia leaching of copper ore. Results agree reasonably with those predicted from small scale batch experiments. The extraction of vanadium from soda roasted steel slag in a 5-deck reactor with carbon dioxide in the gas phase was also satisfactory. Experimental results obtained from the continuous flow 5-deck reactor and those calculated from the batch experimental data using CSTR model were in agreement.