Ternary materials are generally divided into two categories: NCM and NCA. Since NCM is more advantageous in terms of price, the ternary material used on the power battery is mainly NCM. Lithium-ion batteries using NCM materials, if not recycled, are directly discarded, which will cause serious pollution to the environment. Ni and Co elements, organic compounds in the electrolyte and carbon materials of the negative electrode can contaminate water and soil, Ni and Co. The element is also neurotoxic to the human body. Ni and Co elements are high-value non-ferrous metals, of which the highest price of Ni can reach 400,000 yuan / ton, and the price of cobalt rises to 370,000 yuan / ton. It can be said that the recycling of used lithium-ion batteries is not only green, There is also a generous return.
The more traditional recycling method is to use the acid leaching process. First, the waste lithium ion battery needs to be disassembled to obtain the positive electrode powder, then the valuable metal is leached with strong acid, and then treated with an oxidant such as H2O2, reducing agent Na2SO3, and then the solution is purified. Thereafter, a solution of pure Ni, Co, and Mn is obtained by a process of liquid-liquid extraction. Although the method is simple in process, the efficiency is very low, and a large amount of waste water is generated, which pollutes the environment and causes problems such as low Li recovery rate. Xiaobian once had the privilege of participating in the laterite nickel project. The Ni content of the natural Ni ore treated by the traditional hydrometallurgical method is mostly less than 1%, and the Ni content in the ternary material is much higher than this value. The traditional hydrometallurgical process is modified to increase the leaching efficiency.
Traditional metallurgical schools, such as Beijing University of Science and Technology, Northeastern University, and Central South University, have a natural advantage in the recycling of valuable metal ions for lithium-ion batteries, and can apply their experience in non-ferrous metal smelting in the field of battery recycling. Recently, JuntaoHu and others from the University of Science and Technology of Beijing published an article on JournalofPowerSource to report a method for efficiently recovering high-value metals from waste lithium-ion batteries. JuntaoHu's method is to first treat the NCM material by reduction roasting, convert NCM into a simple compound or metals such as Ni, Co and Mn, and then use Li as an alkali metal, the oxide of which can react with water to form soluble LiOH. While the oxides of Ni, Co and Mn do not react with water, the Li element is first separated, and finally Ni, Co and Mn elements are leached by a strong acid leaching process, and then separated in a solution state. This method first separates the Li element, thereby significantly increasing the recovery of the Li element.
For the purpose of protecting intellectual property rights, this article does not report on the key parameters. Please understand that friends in need can leave a message or reply to the original author's contact information in the WeChat public account. In the experiment, JuntaoHu first obtained NCM powder from the waste ternary lithium ion battery, and then mixed NCM with carbon reducing agent by ball milling, then baked in an argon atmosphere, and quickly removed the powder after the roasting. JuntaoHu mainly investigated the effects of calcination temperature (500-900 ° C), the amount of carbon reductant and calcination time on the calcination effect. The main metal element content of NCM powder is shown in the following table.
In order to improve the recovery efficiency of Li element, JuntaoHu uses a CO2 solution leaching method to treat the powder after reduction and calcination, and then filter it to obtain solid-liquid separation, to obtain a solution containing Li element, and the remaining solid powder again uses strong acid. The (H2SO4 solution) was subjected to a leaching treatment, and finally filtered to obtain a solution containing Ni, Co, and Mn elements. It is found that the calcination temperature has an important influence on the recovery rate of metal elements. Appropriate increase of temperature can significantly improve the recovery efficiency. The highest recovery rate of metal elements can reach Li, 89.4%, and Ni and Co exceed 95%. A quantitative study of carbon reducing agents has shown that increasing the amount of carbon reducing agent can increase the recovery of Li element. Studies on calcination events have shown that a 0.5 h calcination is sufficient to adequately reflect the NCM powder.
The separated solution containing Ni, Co and Mn elements is removed by adjusting the pH to 3.5, and then the Fe element in the solution is removed, and then the Ca and Mg elements are removed by fluoride precipitation, and then the Mn element is separated by D2EHPA, and the PC88A is used at different pH. Ni and Co are separated underneath. The solution is then evaporated to dryness to obtain sulfates of Ni, Co and Mn.
JuntaoHu's work provides a very efficient method for lithium-ion battery recycling. It provides a very useful reference for solving the problem of recycling hundreds of millions of lithium-ion batteries. It is also an important contribution of the traditional metallurgical industry to the development of new energy industry. The metallurgist pays tribute.
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