• Polymer Science and Technology
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• v.6 no.1
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• pp.16-21
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• 1995

• Resources Recycling
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• v.7 no.2
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• pp.16-22
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• 1998

Recently, the new technology for the recycling of waste plastics as an alternative he1 of blast furnace ha been developed. In this shldy, the test of plastics injection into a tuyere af the foundry blast furnace were carried out. The injection rate of plastics far this tcst facility war expressed as follows, ${W}_{s}=0.265\frac{{delta}PA}{U}_{g}$, where. Ws, AP, A and Ug are plastic conveying ratc (kgisec), pressure drop between feed hopper and blaqt pressure (alm), cross sectional area of conveying pipe (mi) and superficial velocity of transport air (mhzc) respcctiuely. From the results of semi-continuous test operation during 96 hours, the replacement raho mned out to be 1.38 according to the injection rate of 6. 4 kg-plasticsit-p. With increasing the rate of plaslics injcchon, the content of hydrogen in top gas became increased and the brick temperahlre at bzlly was also increased due to Lhe changes ot the combustion zone shape.

• Proceedings of the IEEK Conference
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• 2001.10a
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• pp.730-733
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• 2001

Separation of PET and PVC is a key technology to achieve effective plastics recycling but no efficient and economically feasible method has been developed yet. The application of flotation was investigated by many researchers but the causes of the selectivity were not clarified. This paper described the adsorption mechanism of wetting agents onto plastics, using the agents which have various polarity and hydrocarbon chain length. It was found that (1) hydrophobic interaction played a predominant role for the adsorption, (2) anionic wetting agents could be adsorbed onto negatively charged plastics with the polar radicals oriented outer part of the plastics, then often depressed plastics more effectively than cationic agents, and (3) PET and PVC could be separated with dodecyamine hydrochloride and sodium dodecyl- sulfonate in the concentration ranges of 1.0$\times$10$^{[-10]}$ $^{6}$ -5.0$\times$10$^{[-10]}$ $^{5}$ and 2.0$\times$10$^{[-10]}$ $^{6}$ -1.0$\times$10$^{[-10]}$ $^{5}$ mo1/1, respectively.

• Resources Recycling
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• v.23 no.5
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• pp.44-54
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• 2014

A standard plastic garbage bag which was discarded from Incheon Metropolitan City was composed of 4.5% recyclable resources (aluminum cans 0.2%, steel cans 2.5%, glass 1.8%), 92.5% resources with recoverable energy (papers 23.0%, plastics 15.5%, combustible etc. 54.0%) and 3.0% non-combustible etc. Recycling is more effective than landfilling for aluminum cans, steel cans, and glass. The energy recovery process using solid refuse fuel (SRF) is more effective than incineration for papers and plastics. Incineration is more effective than recycling for combustible etc. 2,068,948 Million Btu of total energy savings and 21,008 $MTCO_2E$ of total GHG reductions were obtained by the application of the proposed scheme. The total energy savings were equivalent to an economic benefit of 422 billion won per year. The total GHG reductions were equivalent to a GHG benefit of 4,119 passenger cars not running per year. The lower calorific value of the combustible materials was obtained to be 1,936 kcal/kg of papers, 5,079 kcal/kg of plastics and 2,462 kcal/kg of combustible other resources, respectively. If papers and plastics are properly mixed, the mixture can be used as SRF. The lower calorific value of combustible other resources does not meet the quality criteria for refuse derived fuel, therefore its components are inappropriate to used as solid refuse fuel.

• Resources Recycling
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• v.26 no.6
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• pp.73-83
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• 2017

Used small household appliances have a wide variety of product types and component materials, and contain high percentage of black plastics. However, they are not being recycled efficiently as conventional sensors such as near-infrared ray (NIR), etc. are not able to detect black plastic by types. In the present study, an automatic sorting system was developed based on laser-induced breakdown spectroscopy (LIBS) to promote the recycling of waste plastics. The system we developed mainly consists of sample feeder, automatic position recognition system, LIBS device, separator and control unit. By applying laser pulse on the target sample, characteristic spectral data can be obtained and analyzed by using CCD detectors. The obtained data was then treated by using a classifier, which was developed based on artificial intelligent algorithm. The separation tests on waste plastics also were carried out by using a lab-scale automatic sorting system and the test results will be discussed. The classification rate of the radial basis neural network (RBFNNs) classifier developed in this study was about > 97%. The recognition rate of the black plastic by types with the automatic sorting system was more than 94.0% and the sorting efficiency was more than 80.0%. Automatic sorting system based on LIBS technology is in its infant stage and it has a high potential for utilization in and outside Korea due to its excellent economic efficiency.

• Resources Recycling
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• v.26 no.2
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• pp.46-55
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• 2017

In this study, the design methodology of Radial Basis Function Neural Networks is developed with the aid of Laser Induced Breakdown Spectroscopy and also applied to the practical plastics sorting system. To identify black plastics such as ABS, PP, and PS, RBFNNs classifier as a kind of intelligent algorithms is designed. The dimensionality of the obtained input variables are reduced by using PCA and divided into several groups by using K-means clustering which is a kind of clustering techniques. The entire data is split into training data and test data according to the ratio of 4:1. The 5-fold cross validation method is used to evaluate the performance as well as reliability of the proposed classifier. In case of input variables and clusters equal to 5 respectively, the classification performance of the proposed classifier is obtained as 96.78%. Also, the proposed classifier showed superiority in the viewpoint of classification performance where compared to other classifiers.

• Resources Recycling
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• v.19 no.1
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• pp.3-12
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• 2010

Recently, the waste energy utilization has become the main interest in energy industries, due to high oil prices, the low carbon, green growth policy and the RPS (Renewable Portfolio Standards) of our government. Therefore, energy guzzling companies such as district heating companies, textile industries are replacing energy to RDP/RPF. Especially, a lot of big companies are carrying out survey to commercialize the waste plastics pyrolysis technologies developed in Korea. In this paper, status of the pyrolysis technology of Korea were reviewed overall including basis of technology, waste plastics resources, research & development, and commercialization.

• Resources Recycling
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• v.14 no.2
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• pp.3-9
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• 2005

A study on the air and gravity separation has been performed for the removal of chlorine containing materials from ASR of end-of-life vehicles. The gravity separation was also conducted on waste plastics collected from ASR. In this work, ASR were previously shredded to pass through 8 mm sieve prior to separation tests and the gravity separation of waste plastics was conducted for three different particle sizes. The two-stage air classification was conducted with the range of air flow rate of 9~20 M$^3$/hr at first stage and 25~34 M$^3$/hr at second stage, respectively. The fraction of overflow product was remarkably increased in the 2nd stage air classification because of high air flow rate while that of underflow product obtained from 1st stage air classification was found to be 62~66%. From the results of gravity separation on waste plastics, it was also found that the amount of the float product was much greater than sink product. It is believed that the gravity separation may be used very efficiently for the removal of calorine bearing materials from waste plastics.

• Resources Recycling
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• v.22 no.4
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• pp.46-54
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• 2013

The produced quantity of waste plastics including waste vinyls was assumed as about 5 million tons per year. The quantity of waste vinyls produced from the waste recycling center among total quantity of waste plastics was estimated as about 1 million tons per year. Most of waste vinyls produced from the waste recycling center were recycled as refuse plastic fuel(RPF) or recycled feedstock material. In this study, the medium material using waste vinyls was made by the melting process of heat medium heating and the tensile strength was analyzed for checking the usable possibility of recycled waste vinyl material by comparing with the existent product. In order to use the medium material for producing the recycled product, it can be considered that the tensile strength of medium material is more than 100 $kgf/cm^2$.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2020.11a
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• pp.167-168
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• 2020

In order to expand the material recycling of waste plastics made of composite materials, it is necessary to develop the use of material recycling products and to secure their quality stability. In this paper, as a basic study to secure the stability of the quality of household waste plastic material recycling products, the quality characteristics of recycled materials according to the production period were compared and reviewed. In addition, the average tensile strength of the recycled products by production period for 4 months was 12.33 MPa, and the average density was 1.35 g/m3.