Study On Strengthening Selective Crushing Of Spent Lithium-ion Batteries

Now, with the acceleration of the replacement rate of mobile phone, hundreds of millions of spent lithium-ion batteries are produced annually in China. The reutilization of spent lithium-ion batteries has significant economic value and social benefits, which can not only achieve recycling of important metals, such as copper, cobalt, aluminum, etc, but also prevent environment pollution effectively. Crushing is the first link in spent lithium-ion batteries utilization, which provides raw materials for subsequent recovery. The crushing effect directly impacts on the subsequent separation efficiency. The selective crushing characteristics of spent lithium-ion batteries is good. Studying the strengthening of selective crushing of spent lithium-ion batteries can not only make batteries fully dissociated, but also avoid meticulous crushing. Thus, it is vital to research the selective crushing of spent lithium-ion batteries.Firstly, behavioral characteristics of crushing of spent lithium-ion batteries was studied. And the evaluation model of selective crushing of spent lithium-ion batteries was established on the basis of it. Dispersion(ε) and difference(△) of mass distribution of crushing product were proposed. Their expressions are as follows,In order to verify the feasibility of the evaluation model, leaded glass of CRT, coal, waste printed circuit boards and spent lithium-ion batteries that selective crushing characteristics are successively enhanced are selected to crush. And the crushing results are evaluated with the evaluation model. The dispersion and difference of mass distribution of crushing product of the four materials are 0.0225、0.1279、0.1344、0.1924 and 0.0117、0.0395、0.3211、6.6066. The evaluation result indicates that the selective crushing characteristics of the four materials are enhanced in proper order, which is consistent with the fact. Thus, the evaluation model is feasible in theory.Strengthening of selective crushing of spent lithium-ion batteries was mainly studied after establishing the evaluation model. Firstly, we designed a vertical impact crusher which is suitable for spent lithium-ion batteries to crush and analyzed the selective crushing mechanism of spent lithium-ion batteries. The differences of mechanical properties and size between different components are the fundamental reasons that lead to the strong selective crushing characteristics of spent lithium-ion batteries. The vertical impact crusher could strengthen the selective crushing of spent lithium-ion batteries. It has three crushing forms to spent lithium-ion batteries. They are impacting, shearing and friction, and impacting is the key form. Then we did the experiments with the crusher to study the strengthening of selective crushing of spent lithium-ion batteries. Correlation between each factor and the selective crushing effect was got, and formula of selective crushing effect of spent lithium-ion batteries was established by orthogonal test. The significance of each factor which affect selective crushing effect of spent lithium-ion batteries is defined. The decreasing order of factors’ significance is impacting speed>interaction between impacting speed and feeding amount>feeding amount>interaction between crushing time and feeding amount>interaction between impacting speed and crushing time>crushing time.The experimental results indict that when impacting speed, feeding amount and crushing time are 2800 rpm, 500 g, 3min respectively, selective crushing effect of spent lithium-ion batteries up to the best. ε and △ are equal to 0.2252 and 7.3014.In summary, the paper proposes the evaluation model of selective crushing of spent lithium-ion batteries and gets the relationship between the factors and the selective crushing effect of spent lithium-ion batteries, which provide a theoretical basis for spent lithium-ion batteries crushing.