1 Introduction
The packaging of electromechanical products has an important influence on the overall image of the product and its product competitiveness. The environmental problems of product packaging take place in various processes of production, storage, use, and disposal. The massive production of packaging waste has brought serious environmental pollution. The United States produces about 150 million tons of municipal waste each year, of which 1/3 is packaging waste. The annual EU municipal solid waste is about 100 million tons, of which more than 80 million tons are packaging waste. The United States, Germany, the United Kingdom, France, and the Netherlands have all enacted packaging laws that require the recycling and reuse of packaging waste. At present, the annual solid waste production in China is 600 million tons, of which packaging waste accounts for about 1/3, causing serious pollution to China's ecological environment.
2 Current situation and development trend at home and abroad
In 1987, the United Nations Commission on Environment and Development issued the "Our Common Future" declaration. In June 1992, the United Nations Conference on Environment and Development adopted the "Declaration on Environment and Development" and ((21st Century Agenda) and other resolutions worldwide. A green wave centered on protecting the environment and saving resources has been set off.
Most of the packaging is a one-off consumer goods, short life cycle, waste discharge. According to statistics, the annual amount of packaging waste accounts for about one-third of the city's fixed waste, and the volume accounts for 1/2. The amount of emissions is increasing at an annual rate of 10%, which makes the environmental pollution of packaging waste increasingly Prominently, it has attracted the attention of the world’s public and environmental protection community. The environmental protection circles of the United States and other countries have put forward three opinions on reducing the pollution of packaging wastes: First, they should try to use as little or as little packaging as possible; second, they should try to recycle packaging; third, they should be biodegradable and not harmful to the public if they cannot be recycled. surroundings. To this end, Germany, France, the United States, the European Community and other countries have successively formulated strict packaging waste restrictions.
In March 1994, China compiled the "21st Century Agenda of China" and proposed the strategic objectives of sustainable development that promote the coordination of China's economy, society, resources and environment. The National Natural Science Foundation has listed "green design of mechanical and electrical products" as a key funding project. The project takes green packaging and packaging waste recycling as an important research content. It can be foreseen that various types of mechanical and electrical product packaging waste recycling technology will be widely used in China.
3 Recycling of packaging waste
3.1 Metal Packaging Waste Recycling
3.1.1 Significance of Recycling Metal Packaging Waste
Metal resources on Earth are limited. The production of primary metal not only consumes limited mineral resources and consumes large amounts of energy, but also generates a large amount of mine waste, destroys vegetation, and wastes land resources. Recycled metal can save energy, reduce environmental pollution, and extend the time limited mineral resources are exhausted. The energy consumption per ton of primary metal and recycled metal is shown in the table.
3.1.2 Recycling of metal packaging waste
3.1.2.1 Recycling of steel crucibles
After the steel drums are recycled, they must first be categorized according to their purpose and specifications, then cleaned, and the products can be repackaged. Barrels with serious pollution and significant deformation should also be used after renovation, washing, drying and painting. The recovered steel scrap barrels, such as rust, can be scrubbed with a small amount of dilute acid solution and then cleaned immediately with alkali water and clean water. Corrosion inhibitors can also be used to remove rust.
Comparison of energy consumption between original metal and recycled metal (109 joules/ton)
3.1.2.2 Remelt smelting of steel packaging waste
The iron and steel packaging waste that cannot be restored and reused can be smelted. Smelting of scrap steel is economically simple, time-short, and quick-acting, reducing the links of mining, ore mining, and iron making, and can also save equipment investment and reduce the cost of 1/3.
Steel is easily identifiable and magnetic and can be separated by manual or magnetic separation equipment. The scrap steel smelted by scrap steel can be used in 20% to 60% for open hearth, 100% for electric arc furnace and 15%-25% for oxygen converter.
3.1.2.3 Recycling of aluminum and its alloy packaging waste
The output of aluminum is second only to steel, and aluminum is second only to steel in the packaging. Aluminum is silvery white, light in texture, good in ductility, lower in tensile strength than steel, but has higher specific strength (ratio of tensile strength to density). The disadvantages are that the fatigue limit is not high, the melting point is low, the high temperature strength is poor, the hardness is low, and the wear resistance is poor. As a packaging material, aluminum generally uses aluminum plates, aluminum blocks and aluminum foils, and aluminized films. Aluminum scrap is smelted in a counter-current two-chamber reverberatory furnace, an externally-exposed furnace reverberatory furnace, or other types of furnaces to obtain a forgeable aluminum alloy, a cast aluminum alloy, and a deoxidizer for smelting the steel alloy. In addition, aluminium scrap can be recovered from scum and slag using leaching and dry methods. Aluminum product packaging waste can also be used to develop new products - polyaluminum chloride.
This product is a colorless resin, its density often changes with the degree of polymerization, and is easily soluble in water, acids and bases. Dissolved in water, hydrolyzed to form a colloidal solution. The main purpose is to use as a water purifier for domestic water and industrial water, and also for purifying industrial wastewater. Aluminum and its alloy packaging waste recycling has good social and economic benefits. For each ton of waste aluminium recovered, 0.9 tons of electrolytic aluminium can be refined. Save 0.42 tons of bauxite, 0.08 tons of soda ash, and 0.06 tons of electrode material, which can save 20,000 kWh of electricity per hour. It can also greatly reduce environmental pollution.
3.1.2.4 Recycling of Tin Products Packaging Waste
Tin is mainly used for the production of tinplate in the packaging products (ie, tin plating on the surface of the steel plate), followed by the production of tin foil. Recycling of tin products packaging waste can take three methods: First, the general tinplate packaging waste as long as the corrosion is not serious, can be converted into a hardware product, to make the best use of the material. Second, the consumption of tinplate in China is relatively large (600,000 tons/year), and 125 tons of tinplate packaging waste can be recycled with 1 ton of tin. Because tinplate has magnetic properties, it is easier to recycle than waste aluminum. Thirdly, waste tinplate is used as a scrap steel to make the steel contain a small amount of tin (less than 0.1%), which can improve the performance of cast iron.
(to be continued)