Research on pyrolysis of Spent Zinc Manganese Dioxide Batteries in a Ratory kiln

The battery production of China was 20.9 billions in 2003. It has been the first place in the world for a long time. Most of them are zinc-manganese batteries. If they are improperly disposed, the heavy metal substances in them will infiltrate into the soil and pollute the soil and water. The heavy metals will enrich in the human bodies and cause illness. In another aspect, there are a lot of useful things in them: Zn, MnO2 and so on. They should be recovered. This paper retrospects the techniques and research status of recovering the used zinc-manganese batteries. The purpose of these techniques usually contain the aspects as follows: recover Zn, Mn and Hg；recover alloy；recover Zn and MnO2；prepare trace fertilizer；prepare manganese-zinc ferrite；prepare ZnSO4 and MnCO3. The merits and drawbacks of these methods are analyzed in five aspects: effect of the innocent treatment，recycling degree，rank of the product，complexity of the technology and secondary pollution. A method which is fit for industrialization is put forward: firstly, remove Hg from the spent zinc manganese dioxide batteries by pyrogenic process, secondly, remove the other heavy metal contamination from it by hydrometallurgical method and then prepare trace fertilizer. The dimension of the rotary kiln is devised based on the experiential formula of the residence time. The power of the resistance coil and the thickness of the heat preservation material are calculated based on the heat transfer formulae. The pontes of the rotary kiln are airproofed by the united use of heat preservation material and lube. The residence time of the cracked used batteries is adjusted by changing the rotate speed of the rotary kiln and the height difference of it&rsquo;s two ends. The pyrolyzing temperature is changed by the servomechanism which can regulate the power of the resistance coil. The pyrolyzing of the used batteries is studied in the rotary kiln. The tail gas and granules are absorbed by a series of absorbing liquid. The orthogonality pyrolyzing experiments are carried out by changing the temperature, the residence time and the flowrate of the carrier gas. The effects of temperature, residence time and flowrate of carrier gas on Hg removal ratio were investigated. Research was conducted on the Hg absorption by ICP apparatus. The content of the tail gas is mensurated by gas chromatography. The substantial form transformation of the spent zinc manganese dioxide batteries are tested by X-ray. The result indicates: The most efficient condition is in the following: temperature 690℃，residence time 100min，flowrate of carrier gas 0.06m3/h.The most influential factor is residence time. The less influential factor is temperature. Flowrate of carrier gas has little impact on Hg removal ratio. The absorbing solution absorbs almost all the Hg in the tail gas. Approximately 95% of the Hg absorbed in the absorbing solution is simple substance. The unabsorbed Hg remains in the pipelines. The organic impurities largely decompose after pyrolyzed. The productions are C2H4、CH4 and H2, etc. There are redox reactions between graphite C and high oxide of metals. A lot of CO generates and the metal oxide is deoxidized to low chemical valences. It can be concluded from the X-ray diffraction analysis that, when the temperature is 350℃, unconspicuous peaks appear near the 2&theta; value 35&deg;.These peaks evidently swell when the temperature become 500℃, it is the crystal of ZnO and FeO. At the same time, new peaks appear at the 2&theta; value 41&deg;.It owes to the redox reaction between graphite C and high oxide of Mn. The low oxide of Mn forms crystals. The peaks become steady when the temperature is 650℃. After the pyrolytic reation, the relative content of the high valenced Mn oxide changes from 32.2% to 4.6%. The relative content of MnO changes from 6.4% to 38.6%. The metallic elements are mostly in crystal forms. The pyrolysis residue is suitable for preparing organic chelated microelement fertilizer.</span

废锌锰电池回收处理技术

废锌锰电池回收处理的主要技术可分为干法、湿法和干湿法三大类。各回收技术的工艺流程不同,但大多数以回收锌、锰元素为目标。对各种废锌锰电池回收技术的优缺点从无害化程度、资源化程度、产品等级、工艺要求以及二次污染五个方面进行了分析和比较

回转窑热解处理废锌锰电池试验研究

利用回转窑装置热解处理废锌锰电池，考察了热解温度、热解时间和载气流速对热解脱汞效果的影响，研究了汞被吸收的规律、尾气的成分以及废锌锰电池的物质形态变化。研究结果表明：在热解温度为690℃，热解时间为100min，载气流速为0．06m^3／h的条件下脱汞效果最好。热解时间对脱汞效果影响最大，热解温度次之，载气流速的影响很小。吸收液能完全吸收通过吸收瓶的尾气中含有的汞，其中95％以上的汞以单质形式存在。热解残渣中晶态物质多，金属元素呈低价态