(2009-20 10 school year)

Study on the method of eliminating chalk dust.

Student name: Cao Wenxin Class: Class 5, Grade 1.

Name of students in the same group: Cao Wenxin, Jia Shunying, Gao Tianfeng Ting

Instructor's name: Cai Ran

Completion date of the report: 20091February 2.

Attention should be paid to the problem of chalk dust pollution in schools, which has a serious impact on the health of teachers and students. How to eliminate chalk dust pollution as soon as possible should attract the attention of all personnel. The principle and working process of vacuum blackboard eraser are expounded.

Keywords: chalk dust development seriously pollutes the dust and cleans the blackboard eraser

First of all, the topic is put forward:

1 background

Chalk teaching aid is an indispensable tool for teaching at present, and it is one of the most primitive and traditional teaching methods to impart knowledge. Chalk has been used for thousands of years and made an indelible contribution to human education. With the progress of history and the development of society, people's understanding of chalk teaching AIDS has been continuously improved, that is, chalk has brought great progress and contribution to human education, but also brought great harm to teachers and students engaged in education.

According to some national survey data, with the progress of society and the acceleration of social rhythm, the occupational disease rate of teachers is increasing year by year, and occupational diseases are developing in a diversified direction. Among them, pneumoconiosis caused by dust and various acute and chronic respiratory diseases are the most important, harmful and extensive occupational diseases in China. The prevalence of chronic respiratory diseases among primary and secondary school teachers is high, and the common diseases are chronic pharyngitis and vocal cord diseases. Because dust contains carcinogens, the data of China Center for Disease Control and Prevention show that the cancer incidence rate of 38 million full-time teachers in China accounts for 20% of the total cancer incidence rate in China, which is more than 8 times that of the general population.

After studying the distribution and harm of classroom dust with system dynamics model, it is found that the working environment is very similar to the severity of dust harm to workers in front of steelmaking furnace in the diameter space of 3m of the podium.

From the chemical composition of chalk, the main components are calcium carbonate (limestone) and calcium sulfate (gypsum), a small amount of calcium oxide and other small amounts of metal elements such as iron and cadmium. Chalk is a weakly alkaline substance in terms of chemical pH value. According to its physical properties, that is, the main chemical composition, concentration, dispersion, specific gravity, shape, hardness and solubility of chalk in the process of writing and erasing, a lot of dust is generated in the whole teaching process, which floats in the air for a long time, seriously polluting indoor air, endangering the physical and mental health of teachers and students, and endangering modern teaching AIDS with modern characteristics, such as slide projectors, computers and laboratories. At the same time, due to a large number of use, a large number of limestone, minerals and gypsum mines need to be mined, which will cause environmental pollution and ecological damage.

Dust harms the respiratory system of teachers and students, including the lungs and upper respiratory tract, as well as other organs and tissues such as eyes, skin and ears, and easily induces diseases of other organs such as liver, kidney, bone and kidney.

Chalk dust has a strong adsorption capacity, and many harmful bacteria can be adsorbed on fine dust and brought into students' lungs, thus contributing to the occurrence of acute and chronic inflammation, thus causing students to collectively infect respiratory tract and other epidemics. During the course of students' lectures, the indoor and total bacterial count and other sanitary indicators gradually deteriorate, which will interact with fine chalk dust and aggravate the harm of chalk dust to the health of teachers and students.

2 purpose

The reason why the method of eliminating chalk dust is studied is to reduce the harm of chalk dust to teachers, students and others and let everyone live in a healthy environment.

Second, the content of the study:

1 project data collection process

Eight of us discussed the division of labor together. Yu Rui and Jia Lan interviewed some experts and chemistry teachers about the influence of chalk dust on people and the harm of harmful substances in chalk dust to people, and adopted their opinions and suggestions. The rest of the team members consulted relevant books together to learn about the pollution of chalk dust to the environment and some methods to eliminate chalk dust through the internet. Some of them write papers, some keep pictures and word documents in folders, and some print materials bring related books. The division of labor is clear, and everyone is United.

2 research methods

Chalk dust is mainly produced in the process of eliminating chalk characters with blackboard eraser. We mainly study the methods of eliminating chalk dust in the production of chalk and blackboard eraser.

1, research and production of dust-free chalk

(1) At present: original chalk on the market.

(2) Improvement: the original chalk is improved into dust-free chalk, in which grease or polyol is added as a binder, and then raw materials with high specific gravity are added.

(3) Advantages: the specific gravity and volume of chalk are increased, and dust is not easy to fly.

(4) Disadvantages: it is not obvious in practical application, and the cost is high, so it is difficult to popularize.

2. Develop a vacuum eraser.

(1) At present: ordinary cloth.

(2) Improvement: A chalk dust suction device is made, which is connected with the blackboard eraser and the small round box through a conduit.

(3) Benefits: Its function is similar to that of a vacuum cleaner. Start the machine when cleaning the blackboard, so that most of the scattered dust does not spread outward, and the dust is sucked into the container, which is easy to collect.

(4) Disadvantages: People who have just come into contact feel that it is not flexible and convenient to use.

In view of the narrow place in front of the classroom platform, frequent contact between teachers and students, and lively and active students, we think that we should develop a flexible and convenient blackboard eraser that can eliminate chalk dust, that is, improve the existing traditional blackboard eraser, increase the dust suction function, and solve the problem of dust flying outward. We set out to study and make a vacuum blackboard eraser to solve the problem of dust pollution.

Third, the research theory and data analysis.

1 Making a vacuum chalk eraser

The production of vacuum chalk eraser is completed by everyone's participation in discussion and material selection. The dust-absorbing chalk eraser is an injection-molded shell, and two ribs and four limit baffles are cast in parallel on both sides of the shell. The upper end face of the shell is provided with a through hole. The upper end of the screw of the injection-molded eraser holder is threaded, and the eraser body is embedded in the groove of the lower end face of the holder. The fixing frame is located in the middle of the limit baffle. The screw rod passes through the through hole of the shell and is in threaded connection with the upper gland embedded with the spring. The brush is installed in the groove of the rib, and the dust collector is installed on the corresponding side of the shell without rib. Prevent dust from flying and collect dust together.

The dust-absorbing chalk eraser has the advantages of low manufacturing cost, convenient use and low use cost, and can be widely popularized in schools. Using dust-absorbing chalk eraser can effectively reduce the chalk dust in the air and purify the classroom air, with an effective rate of more than 80%.

2 Problems encountered in the production process

We asked Mr. Cai about several problems encountered in the study of "Vacuum Eraser", and through discussion with the teacher, we got the following answers:

1. The principle of the blackboard eraser. A: Now this kind of blackboard eraser has been developed in the market, but it has not been put into use. The principle is roughly as follows: a small vacuum cleaner is installed inside the blackboard eraser. When in use, the dust collector sucks out the chalk dust and stores it in a special container for collecting chalk dust, but the container should be cleaned regularly.

2. Why did chalk dust fall down and why did some of it fly into the air? Answer: Because the process of cleaning the blackboard will produce wind, and the chalk dust is very light, we can consider adding some high-density substances to the chalk dust to make it fall downward and reduce its floating into the air.

3. The principle of vacuum cleaner. Answer: Speed up the air flow inside the vacuum cleaner, so that the internal air pressure is less than the external atmospheric pressure, and the external atmospheric pressure presses chalk dust into the vacuum cleaner.

4. Will the heat generated by friction affect the attraction? A: Under normal circumstances, it will not or has little impact.

5. Will chalk dust be magnetized? Answer: Because it is not magnetic substances such as iron, cobalt and nickel, it is not easy to arrange things like small magnetic needles in chalk dust neatly, and solids will not be magnetized. Therefore, it is of little significance to consider electromagnetic attraction.

Fourth, the final conclusion and other achievements of the research.

The basic idea of 1

People pay more and more attention to knowing that dust pollution is becoming more and more serious. The diffusion of chalk dust and dust pollution were studied, and the harm and treatment of dust pollution were discussed.

② Dust pollution; Chalk ash expansion

③ The source of loose dust; environmental protection

④ Analyze how to prevent the harm of chalk dust.

At present, there are many related products, but they are expensive and have some defects. We want to make a breakthrough in this respect.

2. The main task stage objectives of the activity step stage

1, collect information, consult materials and interview experts.

2. Overall design of a new blackboard eraser.

3. Design drawings, purchase design drawings of raw materials and prepare experimental materials.

4, experimental production data collection, experimental production parts procurement.

5. Design report

6. Exhibition and promotion of works, and exhibition and promotion of achievements.

Team member assignment

Gao Tianfeng Zhang Jiaxin Li Ting Shunying: Looking for information and collecting information.

Yu Rui Jia Lan: Interview experts to buy raw materials and summarize the experiment.

Gao Chen Cao Wenxin: Design Report PPT Production Report Results

Conclusion: Dust-absorbing chalk eraser has a good development prospect and should be popularized in production as soon as possible.

Sixth, sentiment

I learned a lot from this project. In this small group, I felt everyone's friendship and cooperated very tacitly. This is my first time to act alone, but I have gained a lot. Let me feel that the unity between classmates is very important. In this research project, we often encounter some troubles. I don't know where to start with these questions. We have never heard the truth. I wanted to give up in the face of difficulties, but with the encouragement of my peers, I persisted and successfully completed this project. Thank you for your cooperation and support! ————— Cao Wenxin

Through this research study, your friendship with me has deepened, and we have United with each other, discussed with each other and got along well. I learned a lot from this project. For example, the harm of chalk dust to human body, how to prevent the harm of chalk dust to human body, and the collective spirit of the team. Persistent efforts can get things done well, and so on. -Gao Chen

I can successfully complete this research study without your support. Thank you, classmates, and our instructor, Miss Cai! -Jia Lan

I know persistence and unity can do one thing well. This research study has given me a lot of inspiration. I will do everything well in the future with the spirit of unity, friendship and perseverance! Yu Rui

Seven, refer to Baidu Encyclopedia "Chalk"