Study On The Recycling Of Waste Dry Batteries By Aided Vacuum System

The spent batteries contain many kinds of heavy metal, if such batteries are discarded before being suitably disposed, not only is the environment polluted but also a great deal of resources are wasted. Many scientists home and broad have been dreaming of inventing a perfect technology, which can recycle the valuable materials and delete the harm of waste batteries. The author put forward a new technology for treatment of waste batteries based on the past researches, which could recycle mercury and zinc from waste batteries by a vacuum aided system.Its principle is followed:The saturation vapor pressure of components contained in waste dry batteries is different at same temperature, so the materials can be selectively evaporated and condensed by controlling vacuum pressure and temperature.The work the author did as followed:Firstly, the author confirmed the analytical method for mercury of waste battery. The results of experiments indicated that spectrothotometric dermination was a good method for determining mercury in dry battery, and mercury exists mainly in negative pole of battery, but there is a small quantity exists in the accessory substance. So the waste battery must be treated integrally to avoid that mercury was dispersed to environment in the process of treating.Secondly, we investigated the possibility and the rules of recycling mercury by the new vacuum-aided recycling system, the results indicated that: under the condition of the total chamber pressure of 35~620Pa, temperature of 300, the concentration of mercury in waste acid Zinc-Manganese battery can be decreased to a level lower than Ippm after it had been treated for 3h. Under the condition of the total chamber pressure of 35-500Pa, temperature of 300, the concentration of mercury in waste alkaline Zinc-Manganese battery can be decreased to lower than 10ppm after it has been treated for 4h.At the last, through thermodynamics analyzing, we certified that zinc chloride could be transformed to zinc oxide when adding CaO and zinc oxide could be deoxidized under vacuum condition. Based on that we put forward a way for recycling Zinc from battery: We crashed batteries, added Cao and mixed them, heated them under the condition of 800-900 "Cand vacuum. The zinc was recovered with a high recycling rate, the concentration of zinc in treated batteries was less than 0.06%. We found that Enhancing temperature, decreasing vacuum pressure and prolonging distilled time all can accelerate the recovery of zinc.