How to deal with waste plastics now?
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- Unsolveddestoon
- 2021-07-12 23:09
Especially how to process waste plastic into granular plastic?
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- 1Flooranonymity
- 2021-08-05 20:51
In the treatment of urban plastic solid waste, three methods are currently mainly used: landfill, incineration, and recycling. Due to different national conditions, countries are different. The United States focuses on landfilling, while Europe and Japan focus on incineration.
1. Adopting landfill treatment, because the plastic is generally light in quality and not easy to rot, it will cause the landfill to become a soft foundation, which will be difficult to use in the future.
2. Adopt incineration treatment. Because plastics generate large heat and are easy to damage the furnace, and the gas generated after incineration will promote the global warming, some plastics will also release harmful gases and pollute the atmosphere during incineration.
3. Heat recovery method
Most plastics use petroleum as raw materials, and the main component is hydrocarbons, which can be burned. For example, polystyrene burns more calories than dye oil. Some experts believe that sending plastic waste into an incinerator to burn can provide heat for heating or power generation, because 86% of petroleum dyes are directly burned, and only 4% of them are made into plastic products. After the plastic is used up, it will be sent as heat. It is normal to burn it off, and the use of heat is one of the last ways to recycle plastics, which should not be underestimated. However, many environmental protection groups oppose the incineration of plastics. They believe that the incineration method will burn all the messy chemicals in a concentrated manner, which will produce toxic gases. For example, half of the PVC composition is chlorine, and the chlorine gas released during combustion has strong corrosive and destructive power, and it is the culprit of causing evil.
4. Sorting and recycling method
As plastic recycling, the most important thing is to sort. Common plastics include polystyrene, polypropylene, low-density polyethylene, high-density polyethylene, polycarbonate, polyvinyl chloride, polyamide, polyurethane, etc. The difference between these plastics is difficult for ordinary people to distinguish. Most of the plastic classification work is done manually now. Recently, there has been new research progress in machine classification. A German chemical science and technology association invented infrared to identify categories, which is fast and accurate, but the cost of sorting is relatively high.
5. Chemical reduction method
Researchers began to try to extract the chemical composition of the plastic for reuse. The process method used is to cut the long chain of the polymer to restore its original properties, and the cracked raw materials can be used to make new plastics. Some methods are through the addition of chemical elements to promote the chemical cracking of the combined carbon atoms, or the addition of energy to promote its thermal cracking.
6. Hydrogenation solution method
Many experts believe that hydrogenation can be used to treat mixed plastic products. Putting the mixed plastic fragments into a hydrogen reactor and applying a specific temperature and pressure can produce raw materials such as synthetic crude oil and gas. This treatment method can be used to treat polyvinyl chloride waste, and its advantage is that it does not produce toxic dioxins and chlorine. Using this method to process mixed plastic items, according to different plastic components, 60%-80% of them can be refined into synthetic crude oil. Three chemical companies in Germany, BASF and other countries pointed out in a joint research report that hydrogenation is the most excellent method of thermal cracking, and the synthetic crude oil obtained by precipitation is of good quality and can be used for oil refining.
7. Subtractive design method
When designing products, the research and development department takes into account the needs of recycling and disassembly. For materials suitable for recycling in the United States, the focus is not on which plastic should be used to make individual parts, but on materials that can be widely used. , This is a revolutionary change in concept.
1. Adopting landfill treatment, because the plastic is generally light in quality and not easy to rot, it will cause the landfill to become a soft foundation, which will be difficult to use in the future.
2. Adopt incineration treatment. Because plastics generate large heat and are easy to damage the furnace, and the gas generated after incineration will promote the global warming, some plastics will also release harmful gases and pollute the atmosphere during incineration.
3. Heat recovery method
Most plastics use petroleum as raw materials, and the main component is hydrocarbons, which can be burned. For example, polystyrene burns more calories than dye oil. Some experts believe that sending plastic waste into an incinerator to burn can provide heat for heating or power generation, because 86% of petroleum dyes are directly burned, and only 4% of them are made into plastic products. After the plastic is used up, it will be sent as heat. It is normal to burn it off, and the use of heat is one of the last ways to recycle plastics, which should not be underestimated. However, many environmental protection groups oppose the incineration of plastics. They believe that the incineration method will burn all the messy chemicals in a concentrated manner, which will produce toxic gases. For example, half of the PVC composition is chlorine, and the chlorine gas released during combustion has strong corrosive and destructive power, and it is the culprit of causing evil.
4. Sorting and recycling method
As plastic recycling, the most important thing is to sort. Common plastics include polystyrene, polypropylene, low-density polyethylene, high-density polyethylene, polycarbonate, polyvinyl chloride, polyamide, polyurethane, etc. The difference between these plastics is difficult for ordinary people to distinguish. Most of the plastic classification work is done manually now. Recently, there has been new research progress in machine classification. A German chemical science and technology association invented infrared to identify categories, which is fast and accurate, but the cost of sorting is relatively high.
5. Chemical reduction method
Researchers began to try to extract the chemical composition of the plastic for reuse. The process method used is to cut the long chain of the polymer to restore its original properties, and the cracked raw materials can be used to make new plastics. Some methods are through the addition of chemical elements to promote the chemical cracking of the combined carbon atoms, or the addition of energy to promote its thermal cracking.
6. Hydrogenation solution method
Many experts believe that hydrogenation can be used to treat mixed plastic products. Putting the mixed plastic fragments into a hydrogen reactor and applying a specific temperature and pressure can produce raw materials such as synthetic crude oil and gas. This treatment method can be used to treat polyvinyl chloride waste, and its advantage is that it does not produce toxic dioxins and chlorine. Using this method to process mixed plastic items, according to different plastic components, 60%-80% of them can be refined into synthetic crude oil. Three chemical companies in Germany, BASF and other countries pointed out in a joint research report that hydrogenation is the most excellent method of thermal cracking, and the synthetic crude oil obtained by precipitation is of good quality and can be used for oil refining.
7. Subtractive design method
When designing products, the research and development department takes into account the needs of recycling and disassembly. For materials suitable for recycling in the United States, the focus is not on which plastic should be used to make individual parts, but on materials that can be widely used. , This is a revolutionary change in concept.