5-7 OCTOBERISFR2011

43

TOLEDO (SPAIN)

DE-CHLORINATION PROCESS DEVELOPMENT FOR THE PURPOSES
OF BOTH MATERIAL AND THERMAL RECYCLING OF MUNICIPAL VINYL WASTE
S. H. Chung1, J. G. Na1 and J.H. Lee 2
Korea Institute of Energy Research
1Jang-dong Yuseong-gu, Daejeon Korea

Seoul Metropolitan City
211-1 Munhakuijip-gil, Jung-gu, Seoul Korea

e-mail : soohchung@naver.com

Abstract
In Korea, waste plastics including waste vinyl are the items of EPR(Expanded Producer Responsibility). Due to the highoil price, the waste plastics with bottle shape have been sold and recycled as high price. But the waste vinyl is difficult torecycle because of dirt and mixed other material such as papers and aluminum etc. In the course of recycling, PVC
component can be inevitably included and make unfavorable products with high chlorine content. For the effective
recycling of waste vinyl, the twin screw system with heat medium heating was used and is useful for the de-chlorination.
Optimum temperature range for the de-chlorination was 310-350ºC. After the de-chlorination of waste vinyl, the melted
samples were obtained and chipped for the analysis of chlorine and tensile strength. On the basis of chlorine
concentration, the content of 1.4% of original sample was decreased up to 0.6%. The tensile strength of 5.2 MPa of
original sample was increased up to 9.3 MPa.

Keywords: De-chlorination, PVC, Twin Screw, Tensile Strength, Waste Vinyl

1. Introduction
In Korea, the production amount of waste plastics in2009 was 4.5 million tons. But the recycling ratio was low
as less than 50%. Most of waste plastics discharged asa type of bottle have been easily recycled and can beused through the physical treatment of chipping anddrying for the preparation of recycling products as analternative of new polymer plastics.
On the other hand, the waste vinyl may be difficult for theeffective recycling because of dirt and mixed othermaterial. For the material recycling and thermal recycling
by using waste vinyl, the melting process by heating may
be necessary.
In the course of melting as about 250ഒ, the componentof PVC can be decomposed and remained as microbubbles which can decreased the physical properties
such as the tensile strength when the melted waste vinyl
is used for the recycling products.
Also high content of the remained chlorine in the melted
waste vinyl is limited for the use of refuse plastic fuel(RPF).
In Korea, according to the chlorine concentration in RPF
the grade is classified to 4 levels. For the first level ofRPF, the chlorine concentration should be less than
0.5%. Generally the chlorine concentration in waste vinyl
is about 1.0-2.0%.

Without the de-chlorination from waste vinyl, it is difficult
to use as RPF or the raw material with good quality forrecycling products.
In this study, the waste vinyl of municipal waste wasused as feed material for the de-chlorination experiment.
The process with the twin screw type of reactor was used
for effective de-chlorination and overcoming the transfer
problem by the hard material such as metals andceramics which can be inevitably included in waste vinyl.
To heat constantly and effectively, the reactor wascontrolled by the electric heating boiler with heat medium
system.
In the course of de-chlorination, the vapor of hydrochloric
acid was evacuated by vacuum pump and removed byknockout-port and condensing bottle controlled by lowtemperature.
For the investigation of optimum operation conditions, theremained concentration of hydrochloric acid and thetensile strength were analyzed.
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Fig.1 Process Diagram for De-chlorination of Waste
Vinylinteriores libro.indd 43

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6th International Symposium on Feedstock Recycling of Polymeric Materials

2. Materials and Methods
In this study, the waste vinyl in municipal waste was usedas feed material. This was sampled from the collection
area of metropolitan city in Korea.
The concentration of hydrochloric acid of waste vinyl was1.37%.
The waste vinyl was fed into the twin screw reactor as
granule type. The granule type of waste vinyl wasobtained from the crushing of melted waste vinyl madeby recycling company.
The capacity of twin screw reactor is 20 kg/hr.
The hydrochloric gas is sucked to go through therecovery tank and to react NaOH solution by theinduction pump.
The operation temperature of twin screw reactor isconstantly controlled in the range of 310-350ഒ by heatmedium fluid of electric boiler.
Finally the de-chlorinated product as a melting type wasobtained at the end of screw reactor.
In the course of operation, the discharged hydrochloric
gas with the product was removed by the scrubber using
NaOH solution.
The final de-chlorinated product was used for theanalysis of tensile strength with the remained
concentration of hydrochloric acid.
The measurement of tensile strength was followed toKSM3006 for the regulation of Korea Standard which canbe used for the thermoplastic product.

3. Results and Discussion
One of effective controlling factors was heating
temperature of reactor which can decompose PVC
component and decrease the viscosity of melted waste
vinyl to increase the mixing effect and the de-chlorinationin the reactor.
The optimum de-chlorination temperature was 340-350ºC
higher than 230ºC of theoretical decomposition
temperature. On this experimental condition, theremained concentration of hydrochloric acid in final
product was 0.6%.
The remained concentration of hydrochloric acid in theproducts was decreased on the increase of temperature.
The concentration of hydrochloric acid was changed from
1.37% of original sample to 0.6% of final product treatedby 350ºC.
By these final products, the values of the tensile strength
on the operation temperatures were compared with eachother.
The value of 5.2 MPa for the original sample waschanged up to the value of 9.4 MPa for the final producttreated by 350ºC.
This indicates that the melted plastic with low
concentration of hydrochloric acid in has higher tensile
strength than that with high concentration.

interiores libro.indd 44Fig. 2 De-chlorination Effects on the Operation
Temperature

Figure 3 Comparisons of Values of Tensile Strength on
the Operation Temperature

4. Conclusions
The waste vinyl with PVC component produced as amunicipal waste can be de-chlorinated by the twin screw
reactor with indirect heating.
According to the increase of operation temperature, theremained concentration can be decreased from 1.37% oforiginal sample to 0.6% of product treated by 350ºC.
The values of tensile strength was increased from 5.2
MPa of original sample to 9.4 MPa on the sameconcentration of hydrochloric acid for final producttreated by 350ºC.

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Thermal degradation of mixed plastic waste to aromatics
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