Venue: street, supermarket
Practice topic: Harm of waste batteries and treatment methods
Practice goal: to clarify the significance of waste classification and recycling. Enhance the awareness of environmental protection
Practical achievements: 1. Summarize people's attitude towards waste batteries
2. Draw a scientific method to recycle waste batteries
3. Enhance our practical ability
Investigation report:
1. Theme: the harm of waste batteries and its treatment methods
2. Activity background: The harm of waste batteries has been paid more and more attention by more and more countries.
III. Ideas and methods of activities: field investigation, visiting experts and searching for information
IV. Expected results: experimental samples drawn and made
V. Preparation: .1. Understand the hazards of waste batteries
2. Learn from the measures taken by countries around the world to recycle waste batteries. Design a set of activity plan for recycling waste batteries suitable for senior high school students
VI. Assignment of tasks: ① Division of tasks: field investigation (2) Visiting experts (3) Checking written materials (4) Issuing proposals
VII. Schedule: Searching for relevant materials from February 6 to 7, Have an overall understanding of the subject and learn from predecessors' experience. Design a recycling plan from February 8th to 9th.
Carry out a publicity campaign for recycling waste batteries from February 1th to 11th.
Summarize practical activities on February 12th.
VIII. Summary of activities:
How to recycle waste batteries in China.
1. Strengthen market spot checks and ban mercury.
The target steps of eliminating mercury-containing batteries have been made clear. However, some enterprises lag behind the national requirements, and even a few enterprises use other brands to produce high-mercury batteries. These illegal acts can only be stopped by strengthening market spot checks and punishing enterprises that continue to sell and produce over-standard batteries. It is suggested that the industrial and commercial and quality supervision departments with the functions of market inspection and punishment go to the point of sale for sampling and testing. If the mercury content of the battery exceeds the standard, the inferior battery will be confiscated, fined and the responsibility of the wholesaler and producer will be investigated. Social forces should be mobilized to report enterprises that produce and sell inferior batteries by means of rewarding reports.
2. Carefully collect waste batteries
The mercury content in batteries is low (even high-mercury batteries), and the consumer groups are scattered. Burying waste batteries with domestic garbage will not cause too much pollution (due to the protective effect of battery shell and the dilution effect of a large amount of garbage). However, if a large number of waste batteries are concentrated in one place, coupled with poor treatment (such as peeling off the shell, recycling valuable parts and discarding the residue at will), it may cause mercury pollution in some areas. Therefore, some units and individuals should properly keep them and hand them over to units with storage and processing conditions when carrying out collection activities. It is not appropriate to collect waste batteries on a large scale before there are qualified treatment or utilization facilities.
the waste batteries that have been collected at present should be arranged by the municipal sanitation department for centralized storage in cities. After the qualified facilities are completed, they will be treated or utilized.
3. Voluntary utilization
Although it is not necessary to collect dry batteries separately from the perspective of pollution control, some units hope to recycle metals such as zinc, manganese and iron from the perspective of saving resources. Like other waste comprehensive utilization projects, the scrap metal recycling industry is greatly impacted by the fluctuation of raw material market price and downstream demand, and the use of waste dry batteries may make ends meet in a certain period of time. Under the condition of market economy, it is not allowed for financial subsidies to enterprises that use waste batteries, but only the principle of voluntary participation of enterprises. If the enterprise has the technology and management ability, or from the perspective of public welfare, it can also carry out this business even if it is willing to do it at a loss. Reuse facilities for mercury-containing batteries should be built in sparsely populated and environmentally insensitive areas (such as mercury mines), with advanced technical management level and large scale, and should not be turned into crude workshop-style utilization plants.
it should be noted that units engaged in the collection and utilization of waste batteries should also abide by laws and regulations on occupational disease prevention, environmental protection, land planning and so on. In addition to the reduction or exemption according to law, taxes shall be paid according to regulations. You can't go against the law just because you save resources.
4。 Suggestions on the treatment of waste batteries
In the field of the treatment of waste batteries, with the continuous development of the battery industry, the treatment methods and technologies required for different types and specifications of waste batteries have also formed accordingly. Therefore, we put forward three suggestions: solidification and deep burial, storage in old mines, and recycling. The recycling of waste batteries is the focus of current industry management. Use the "three-oriented" principle to manage waste batteries, that is, adopt the guiding ideology of reduction, resource utilization and harmlessness to prevent and control the pollution of waste batteries.
to strengthen the construction of policies and regulations on the management of waste batteries, governments at all levels should take the Law of the People's Republic of China on the Prevention and Control of Environmental Pollution by Solid Wastes as a guide, and formulate policies, regulations and practical implementation rules that are in line with the actual situation according to the present situation of the generation and management of waste batteries and the external environment of social and economic development. The competent administrative department of environmental protection of the State shall promulgate the basic policies and regulations as soon as possible to guide the management and disposal of waste batteries throughout the country. All provinces and cities should formulate corresponding local policies and regulations on the management and disposal of waste batteries in light of their specific development needs. Small towns can issue necessary implementation rules according to local conditions to specifically implement the recycling and disposal of waste batteries.
There are few waste battery recycling bins, and the public's awareness is still weak. We hope that the government can make a lot of waste battery recycling boxes and hang them at the door of every unit, school, shopping mall and crowded places to create an atmosphere in which everyone is used to recycling waste batteries. The government sent a special person to collect used batteries. Publicize the dangers of used batteries to every citizen. The units and individuals that actively participate in the recycling of waste dry batteries should be vigorously publicized and commended. So as to achieve unified recycling, in order to reduce urban pollution.
China is a big country in battery production and consumption, and waste battery pollution has become a major environmental problem to be solved urgently. However, it is difficult to attract investors because of the low return rate and long benefit cycle, so it is difficult to form an industrial scale and generate benefits.
in fact, the waste battery recycling industry is not unprofitable. Waste batteries contain a large number of recyclable heavy metals and acid solutions. For example, the recycling of lead-acid batteries is mainly based on the recycling of waste lead, including the use of waste acid and plastic shells. At present, the metal recycling rate of lead-acid batteries for used cars in China is about 8-85%.
according to industry estimates, if 1, waste batteries are treated every day, after all kinds of expenses are removed, the profit will be about 2, yuan. With 7 billion batteries and 5% utilization rate, the annual profit can reach more than 6 million yuan. It can be seen that the implementation of scale operation in this field can completely create benefits.
edit the summary of recycling methods of waste batteries in this paragraph
1. recycling of waste Ni-MH batteries
1.1 failed anode alloy powder
peel off the shell of failed MH/Ni batteries, separate the anode sheet from the battery core, use ultrasonic vibration and other physical methods to obtain failed anode powder, and then chemically treat it to obtain the treated anode powder, which is pressed into tablets and repeatedly melted in a non-consumable vacuum arc furnace for 3 ~ 3 times. Remove the oxide layer on the surface of the molten ingot, crush it, mix it evenly, measure the percentage content of mixed rare earth, nickel, cobalt, manganese and aluminum by ICP method, supplement other necessary elements based on the content of nickel according to the loss of hydrogen storage alloy elements, and then smelt it, and finally get the recovered alloy with excellent performance.
1.2 recovery of failed MH/Ni battery anode alloy
the failed anode powder is chemically treated, and the oxide on the alloy surface is destroyed by the etching of the treatment solution, but the etching influence of other unoxidized elements and conductive agents in the alloy is minimized. Use .5 mol? L-1 acetic acid solution, the failed alloy powder was treated at room temperature for .5h, then washed with distilled water and dried under vacuum. The results show that the main structure of AB5 hydrogen storage alloy has not changed, and it still belongs to CaCu5 hexagonal structure, but the impurity phases of Al(OH)3 and La(OH)3 in the negative electrode powder basically disappear, indicating that the oxides on the surface of these oxides are almost completely dissolved after chemical treatment. The charge and discharge performance of the failed anode powder after chemical treatment was compared with that of the original alloy powder for battery production and the failed alloy powder without chemical treatment. The discharge specific capacity of the failed anode powder after chemical treatment was 23mAh higher than that of the failed anode powder without chemical treatment. G-1 shows that after chemical treatment, the effective components of hydrogen storage alloy in failed negative electrode powder are increased because most of the surface oxides are removed. XPS results show that the concentration of nickel atoms on the surface of the negative electrode powder has increased from 6.79% before chemical treatment to 9.3%, which shows that a nickel-rich layer with high electrocatalytic activity has been formed on the surface of the alloy after chemical treatment, which not only improves the electrocatalytic activity of the hydrogen storage electrode, but also provides a diffusion path for hydrogen atoms, thus improving the discharge performance of the electrode. However, compared with the original alloy powder used to make batteries, the failed anode powder after chemical treatment still has a lower specific discharge capacity of 9mAh? G-1, on the one hand, may be because the oxidation of the alloy is not limited to the surface, but may also go deep into the alloy. Chemical treatment only removes the oxide on the surface, but the deep oxidation inside the particles is not completely removed; On the other hand, it may be that the specific surface area of the alloy is increased due to pulverization, and at the same time, it is easier for the alloy to react with O2 and be corroded by electrolyte. The discharge performance of the alloy is decreased due to the interaction of * * *. Therefore, chemical treatment alone can not restore the function of the failed anode, and smelting treatment is needed.
the chemically treated anode powder is smelted for the first time in a non-consumable electric arc furnace. After polishing the obtained alloy ingot and removing surface impurities, the content of each element was analyzed. As a result, it can be seen that the element content in the alloy deviates from the original alloy, and the nickel content is much higher than that in the original alloy powder. This is because nickel powder is added as a conductive agent in the process of making electrodes. In order to effectively use it, based on it, the content of other elements is adjusted to meet the proportion of elements with the composition of MmNi3.5Co.7Mn.4Al.3, and the second smelting is carried out. After smelting, the obtained alloy ingot was crushed and ground, and its structure was measured, which was CaCu5 type and no other impurities were generated.
By testing the charge and discharge performance of the recovered alloy powder, it can be seen that the discharge capacity of the recovered alloy powder is about 1mAh higher than that of the failed anode powder. The discharge capacity of g-1 is basically the same as that of the original alloy powder, and the discharge plateau voltage of the recovered alloy powder is about 2mV higher than that of the original alloy powder, which may be due to the fact that the composition and microstructure of the alloy have been improved after several smelting in the process of alloy recovery.
2. Waste lithium-ion secondary battery
Cobalt and lithium were recovered from waste lithium-ion secondary battery by alkali dissolution → acid leaching →P24 extraction purification →P57 extraction separation of cobalt and lithium → back extraction recovery of cobalt sulfate and raffinate deposition recovery of lithium carbonate. The experimental results show that about 9% aluminum can be removed in advance by alkali dissolution, and the recovery rate of cobalt leaching by H2SO4+H2O2 system is over 99%. After P24 extraction and purification, the impurity contents are Al3.5mg/L, Fe.5mg/L, Zn.6mg/L, Mn2.3mg/L, Ca <: .1mg/L; When the pH is 5.5, the separation factor βCo/Li can be as high as 1×15. Lithium carbonate is deposited with saturated sodium carbonate above 95℃, and the lithium carbonate obtained can meet the requirements of zero-grade products, and the primary lithium precipitation rate is 76.5%.
the lithium-ion secondary battery consists of a shell and an internal battery core, and the shell is made of stainless steel, nickel-plated metal steel shell or plastic shell; The inner cell of the battery is a coiled structure, which is mainly composed of a positive electrode, a negative electrode, a separator and an electrolyte. Generally, the cathode material of a battery consists of about 9% lithium cobaltate active substance, 7% ~ 8% acetylene black conductive agent and 3% ~ 4% organic adhesive, which are evenly mixed and smeared on an aluminum foil current collector with a thickness of about 2μm; The negative electrode of the battery is composed of about 9% negative active material carbon material, 4% ~ 5% acetylene black conductive agent and 6% ~ 7% adhesive, and then coated on a copper foil current collector with a thickness of 15 μ m.. The thickness of the anode and cathode is about .18～.2mm, and the middle is separated by a separator with a thickness of about 1 μ m. The separator is generally made of polyethylene or polypropylene, and the electrolyte is an organic carbonate solution of lithium hexafluorophosphate. Remove the packaging and shell of the waste lithium ion secondary battery, take out the battery core, and separate the cathode material.
IX. Significance of the activity: It has improved our awareness of environmental protection and enhanced our awareness of social responsibility.