one. Recovered heat energy method

Most plastics use petroleum as the raw material, and the main component is hydrocarbons, which can be burned. For example, polystyrene burns more heat than dye oil. Some experts believe that sending plastic waste to an incinerator can provide the heat for heating or power generation. Because 86% of petroleum dyes are directly burned, only 4% of them are made into plastic products, and plastic is used up and sent as heat energy. Burning is normal, and the use of heat energy is one of the last methods for plastic recycling and should not be taken lightly. However, many environmental groups oppose the burning of plastics. They believe that the incineration method will concentrate all the chaos of chemicals and cause toxic gases. If half of the PVC component is chlorine, chlorine emitted from combustion will have a strong erosive effect, and it will be the culprit for causing dioxin.

At present, Germany has 200,000 tons of PVC waste each year, of which 30% is burned in the incinerator, burning people's minds, and the law has to formulate countermeasures. The Federal Environment Agency of Germany has stipulated that all incinerators must meet a limit of less than 0.1 ng (nanograms) per cubic meter of exhaust gas. Although the air pollution standards for incinerators in Germany are already recognized as high standards in the world, they still do not dare to say that the combustion methods will not release harmful substances due to mechanical failure. Therefore, it is foreseeable that environmental protection groups in various countries will strongly oppose the incineration method to recover heat energy.

two. Sorting recovery method

As plastic recycling, the most important is to classify. Common plastics are polystyrene, polypropylene, low-density polyethylene, high-density polyethylene, polycarbonate, polyvinyl chloride, polyamide, polyurethane, etc. The difference between these plastics is generally difficult to distinguish. Most of the current plastics classification work is done manually. Recent advances in machine classification have led to new research. A German chemical science and technology association has invented infra-red to identify categories. It is fast and accurate, but it has high sorting costs.

three. Chemical reduction researchers began trying to extract the chemical composition of plastics for reuse. The process used is to cut the long chains of polymers and restore their original properties. The cracked materials can be used to make new plastics. Some methods promote the chemical cracking of bonded carbon atoms by adding chemical elements, or add energy to promote thermal cracking.

German company Bayer developed a hydrolytic chemical reduction method to crack the PUC sponge pad. Tests have shown that the chemical reduction method is technically feasible, but it can only be used to handle clean plastics, such as corner powders and other plastic wastes produced in the manufacturing process. Plastics that have been used in the home and are contaminated with other contaminants are difficult to dispose of using chemical decomposition. The application of this reduction method, until the 21st century will not be a large number of use of hydrolysis to deal with waste. Some new chemical decomposition methods are still in the process of research, the United States Ford Motor Company is currently using esterification method to deal with automotive plastic parts.

The American Institute of Technology in Ransom developed a solution that can break down plastic waste, heating this patented solution together with six different types of plastic that are mixed together. At different temperatures, six polymers can be extracted separately. In the experiment, the polystyrene plastic chips and related solutions were mixed at room temperature into a dissolved state, which was sent to a sealed container for heating, and then sent to a lower pressure “flashing chamber” where the solution quickly evaporated. Recycling, and the rest is pure polystyrene that can be reused.

It was alleged that the purification device used in the research could purify 1 kg of polymer per hour. New York State Government and Niagara. Mohawk Power is planning to join forces to build a small pilot plant. Investors claim that after the plant is completed, 4 tons of polymer material can be recovered per hour. Its cost is only 30% of the raw materials for production and it has very obvious commercial value.

four. Hydrolysis method

Many experts believe that hydrogenation can be used to process mixed plastic products. The mixed plastic chips are placed in a hydrogen reactor and subjected to a specific temperature and pressure to produce raw materials such as synthetic crude oil and gas. This treatment can be used to treat PVC waste, which has the advantage of not producing toxic dioxins and chlorine. Using this method to process mixed plastic articles, according to different plastic components, 60%-80% of them can be refined into synthetic crude oil. Three chemical companies in Germany and other countries, BASF, pointed out in their common research report that hydrogenation is the best method for thermal cracking, and the synthetic crude oil obtained from the analysis has good quality and can be used for oil refining.

The University of Kentucky in Lexington, United States, invented a process for converting waste plastic into high-quality plastic fuel oil. The fuel produced in this way is very much like crude oil, even lighter than crude oil, and more easily extracted into high-octane fuel oil. This kind of fuel oil produced from waste plastics does not contain sulfur and has very few impurities. A similar method is used to liquefy the plastic with coal. Can also produce high quality fuel oil.

Researchers mixed various plastics with zeolite catalysts, tetralin, etc. in a shower and put it into a reactor called a “pipe bomb”. They pressurize and heat with hydrogen to promote macromolecule plastics. Decomposes into smaller molecular weight compounds. This process is similar to that in crude oil processing. After this waste plastic processing, the oil production rate is very high, and the polyethylene plastic bottle's oil output rate can reach 88%. When waste plastic and coal are mixed and liquefied in a roughly 1:1 ratio, better quality fuel oil can be obtained. After the economic benefits of this process are evaluated, it is expected that the use of waste plastics to produce fuel oil will be transformed into a blast furnace benefit within 5-10 years. At present, Germany has begun to establish a reactor with the hope of producing 200 tons of plastic fuel in Botepo.

(to be continued)