The method comprises the following steps: collecting, sorting, cleaning, drying, recycling and granulating of waste plastics
Waste plastics sorting
The source of waste plastics complex, often mixed with metal, rubber, fabric, yarn and other mud impurities, and the different varieties of plastics are often mixed together, it will not only cause difficulties for the recycling of waste plastics processing and production of the product quality impact, but also the damage of metal impurities mixed with processing equipment. Therefore, in the production of products with waste plastics, not only to remove all kinds of impurities in waste plastics, but also to separate the different varieties of plastic, only in this way can be made of high quality recycled products.
The separation methods of waste plastics are manual sorting, magnetic separation, density separation, electrostatic separation, flotation, temperature separation and air separation.
1 manual sorting
Manual sorting steps are as follows:
(1) removal of metallic and non-metallic impurities and removal of waste plastics with severe weight loss.
(2) according to the products, such as film (agricultural film, color film packaging), bottle (bottle of mineral water, carbonated beverage bottles), cup and box, shoes, sandals, foam, and other scrap are classified according to different classification section identification method of plastic varieties, such as polyethylene, polypropylene, PVC, polystyrene polyester, etc..
(3) the waste plastic products which are classified by the above are sorted according to the color depth and quality. The colors can be divided into the following categories: black, red, brown, yellow, blue, green and transparent.
2 magnetic separation
The main purpose of magnetic separation is to remove the impurities in the scrap iron and steel in the waste plastics, because of these fine iron and steel chips is not easy to use manual sorting method to remove, therefore, must be cleared by magnetic separation method.
3 density separation
This is the density separation method has the properties of different density separation using different plastics, usually solution sorting, hydraulic sorting and centrifugal density separation method, separation method is the solution of mixed solution of waste plastic into a certain density, then according to the waste plastic in the solution to the ups and downs of the state sorting.
The advantages of solution sorting method is simple and feasible, as long as the choice of preparing one or several solution can be mass separation, and avoid the tedious manual sorting, it is some kind of plastic density very close, therefore, to isolate high purity difficult.
In order to improve the separation efficiency, the hydraulic separator is often used for cleaning. Centrifugal density separator.
4 electrostatic separation
Electrostatic separation is a kind of method that uses different electrostatic attraction. The first step is the plastic area is about 10mm2 crushed into pieces, after drying, sorting by high-voltage electrode, for a variety of mixed waste plastics by repeatedly sorting, this is because each time through the primary voltage of high voltage electrode can only set treasure sorted out a kind of plastic. The electrostatic separation method is especially suitable for the polarity of PVC, the separation purity up to one hundred percent.
5 flotation separation
Flotation is the use of wetting agent to change water wettability on the plastic surface, some of the plastics changed from hydrophobic to hydrophilic sink, while still adhering to the surface of hydrophobic plastic bubble floating method so as to achieve the purpose of separation. Flotation separation of different types of plastics, and the density of plastic, shape, size, etc., it is the use of water on the surface of the plastic properties of different wetting to be sorted.
6 temperature separation
The temperature difference is also called the low temperature separation, which is a method of using different kinds of plastics with different brittleness temperature. The concrete method is as follows: the mixed waste plastics are cooled and crushed in a cooler with a temperature of 50 degrees after being crushed at one time, and the brittleness temperature is below the temperature of 50 degrees. The crushed plastic is then cooled and crushed in a cooler at a temperature of 100 degrees. The coolant is cooled by liquid nitrogen to 140 degrees.
Application of solution density / (g/cm3) preparation method:
Plastic solution floating in solution
Water 1 - polyethylene, polypropylene, PVC, polystyrene
Salt solution (saturated) 1.19 (25 degree) water 74ml salt 26G polystyrene, ABS PVC, PMMA
Alcohol solution (58). 4% (25 degrees) water 100ml95% alcohol 160ml water polypropylene polyethylene ()
Alcohol solution (55). (4%) (25 degree) 100ml95% alcohol 140ml low density polyethylene HDPE
Calcium chloride aqueous solution 1.27 150ml calcium chloride 100g (industrial) polystyrene, organic glass, polyvinyl chloride
7 air separation
The utility model relates to a method for separating the crushed material in the separation device, the wind blows from the transverse or the reverse direction, and the difference between the resistance of the air flow and the resultant force of the self weight is different. Due to the size of the particle size will affect the effect of sorting, so this method requires the size of the crushed after the uniform thickness. This method can also be used to sort the plastic mixed with gravel and sand, etc.. Two, waste plastic cleaning and drying Waste plastics are usually in different degrees contaminated with oil, garbage, sediment, these impurities will seriously affect the quality of recycled plastic products, therefore, must be cleaned of waste plastics, cleaning methods are manual cleaning and mechanical cleaning. (1) manual cleaning and dry cleaning should be decided according to the variety of products and the degree of pollution. General agricultural film and packaging film cleaning process is as follows: warm alkaline wash (to oil) - Scrub - Leng Qingshui rinse - dry. Packaging of toxic drugs, the film and the cleaning process of the container are as follows: Lime water cleaning (neutralization and detoxification) - Scrub - cold water rinse - drying
(2) mechanical cleaning and dry cleaning machinery with intermittent and continuous two, is the first batch of soaking time on the dissolution of waste plastics with hot alkaline solution, then make the film by mechanical stirring friction and impact each other, in order to achieve the purpose of removing contaminated dirt, and then remove the thin film method after cleaning. Continuous type is an intermittent improvement. The waste plastic is fed continuously, and the film after cleaning is discharged continuously.
(source: Alibaba plastic price Library)
Waste plastics sorting
The source of waste plastics complex, often mixed with metal, rubber, fabric, yarn and other mud impurities, and the different varieties of plastics are often mixed together, it will not only cause difficulties for the recycling of waste plastics processing and production of the product quality impact, but also the damage of metal impurities mixed with processing equipment. Therefore, in the production of products with waste plastics, not only to remove all kinds of impurities in waste plastics, but also to separate the different varieties of plastic, only in this way can be made of high quality recycled products.
The separation methods of waste plastics are manual sorting, magnetic separation, density separation, electrostatic separation, flotation, temperature separation and air separation.
1 manual sorting
Manual sorting steps are as follows:
(1) removal of metallic and non-metallic impurities and removal of waste plastics with severe weight loss.
(2) according to the products, such as film (agricultural film, color film packaging), bottle (bottle of mineral water, carbonated beverage bottles), cup and box, shoes, sandals, foam, and other scrap are classified according to different classification section identification method of plastic varieties, such as polyethylene, polypropylene, PVC, polystyrene polyester, etc..
(3) the waste plastic products which are classified by the above are sorted according to the color depth and quality. The colors can be divided into the following categories: black, red, brown, yellow, blue, green and transparent.
2 magnetic separation
The main purpose of magnetic separation is to remove the impurities in the scrap iron and steel in the waste plastics, because of these fine iron and steel chips is not easy to use manual sorting method to remove, therefore, must be cleared by magnetic separation method.
3 density separation
This is the density separation method has the properties of different density separation using different plastics, usually solution sorting, hydraulic sorting and centrifugal density separation method, separation method is the solution of mixed solution of waste plastic into a certain density, then according to the waste plastic in the solution to the ups and downs of the state sorting.
The advantages of solution sorting method is simple and feasible, as long as the choice of preparing one or several solution can be mass separation, and avoid the tedious manual sorting, it is some kind of plastic density very close, therefore, to isolate high purity difficult.
In order to improve the separation efficiency, the hydraulic separator is often used for cleaning. Centrifugal density separator.
4 electrostatic separation
Electrostatic separation is a kind of method that uses different electrostatic attraction. The first step is the plastic area is about 10mm2 crushed into pieces, after drying, sorting by high-voltage electrode, for a variety of mixed waste plastics by repeatedly sorting, this is because each time through the primary voltage of high voltage electrode can only set treasure sorted out a kind of plastic. The electrostatic separation method is especially suitable for the polarity of PVC, the separation purity up to one hundred percent.
5 flotation separation
Flotation is the use of wetting agent to change water wettability on the plastic surface, some of the plastics changed from hydrophobic to hydrophilic sink, while still adhering to the surface of hydrophobic plastic bubble floating method so as to achieve the purpose of separation. Flotation separation of different types of plastics, and the density of plastic, shape, size, etc., it is the use of water on the surface of the plastic properties of different wetting to be sorted.
6 temperature separation
The temperature difference is also called the low temperature separation, which is a method of using different kinds of plastics with different brittleness temperature. The concrete method is as follows: the mixed waste plastics are cooled and crushed in a cooler with a temperature of 50 degrees after being crushed at one time, and the brittleness temperature is below the temperature of 50 degrees. The crushed plastic is then cooled and crushed in a cooler at a temperature of 100 degrees. The coolant is cooled by liquid nitrogen to 140 degrees.
Application of solution density / (g/cm3) preparation method:
Plastic solution floating in solution
Water 1 - polyethylene, polypropylene, PVC, polystyrene
Salt solution (saturated) 1.19 (25 degree) water 74ml salt 26G polystyrene, ABS PVC, PMMA
Alcohol solution (58). 4% (25 degrees) water 100ml95% alcohol 160ml water polypropylene polyethylene ()
Alcohol solution (55). (4%) (25 degree) 100ml95% alcohol 140ml low density polyethylene HDPE
Calcium chloride aqueous solution 1.27 150ml calcium chloride 100g (industrial) polystyrene, organic glass, polyvinyl chloride
7 air separation
The utility model relates to a method for separating the crushed material in the separation device, the wind blows from the transverse or the reverse direction, and the difference between the resistance of the air flow and the resultant force of the self weight is different. Due to the size of the particle size will affect the effect of sorting, so this method requires the size of the crushed after the uniform thickness. This method can also be used to sort the plastic mixed with gravel and sand, etc.. Two, waste plastic cleaning and drying Waste plastics are usually in different degrees contaminated with oil, garbage, sediment, these impurities will seriously affect the quality of recycled plastic products, therefore, must be cleaned of waste plastics, cleaning methods are manual cleaning and mechanical cleaning. (1) manual cleaning and dry cleaning should be decided according to the variety of products and the degree of pollution. General agricultural film and packaging film cleaning process is as follows: warm alkaline wash (to oil) - Scrub - Leng Qingshui rinse - dry. Packaging of toxic drugs, the film and the cleaning process of the container are as follows: Lime water cleaning (neutralization and detoxification) - Scrub - cold water rinse - drying
(2) mechanical cleaning and dry cleaning machinery with intermittent and continuous two, is the first batch of soaking time on the dissolution of waste plastics with hot alkaline solution, then make the film by mechanical stirring friction and impact each other, in order to achieve the purpose of removing contaminated dirt, and then remove the thin film method after cleaning. Continuous type is an intermittent improvement. The waste plastic is fed continuously, and the film after cleaning is discharged continuously.
(source: Alibaba plastic price Library)
Shantou Ming Fa Machinery Co., Ltd.
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