TREATMENT OF TOXIC WASTES USING AN HYDROMETALLURGICAL PROCESS

A hydrometallurgical process, which consists of a hypochlorite leachin g of chlorine-alkali sludge followed by a solid liquid separation with cake washing is presented. The effect of temperature, level of agitat ion, amount of chlorine in the leaching. solution and its consumption in the behaviour of the leaching process was analysed. The results sho wed that to achieve higher leaching kinetics, there is not any advanta ge of temperature higher than 25 degrees C, and that there is no need for very strong agitation. It was noted that the chlorine consumption is higher than stoichiometrically necessary. Some flowsheets are propo sed with the corresponding computer worksheets. One of them was checke d and confirmed by a continuous experiment on laboratory scale. Recirc ulation of the leaching solution and of the filtration cake washing wa ter diminished the necessary reagent consumption. However the percenta ge of mercury extraction is slightly decreased due to the increase of mercury concentration in the initial leaching solution.