Py–FTIR–GC/MS Analysis of Volatile Products of Automobile Shredder Residue Pyrolysis

Automobile shredder residue (ASR) pyrolysis produces solid, liquid, and gaseous products, particularly pyrolysis oil and gas, which could be used as renewable alternative energy resources. Due to the primary pyrolysis reaction not being complete, the yield of gaseous product is low. The pyrolysis tar comprises chemically unstable volatiles before condensing into liquid. Understanding the characteristics of volatile products will aid the design and improvement of subsequent processes. In order to accurately analyze the chemical characteristics and yields of volatile products of ASR primary pyrolysis, TG–FTIR–GC/MS analysis technology was used. According to the analysis results of the Gram–Schmidt profiles, the 3D stack plots, and GC/MS chromatograms of MixASR, ASR, and its main components, the major pyrolytic products of ASR included alkanes, olefins, and alcohols, and both had dense and indistinguishable weak peaks in the wavenumber range of 1900–1400 cm−1. Many of these products have unstable or weaker chemical bonds, such as =CH–, =CH2, –C=C–, and –C=CH2. Hence, more syngas with higher heating values can be obtained with further catalytic pyrolysis gasification, steam gasification, or higher temperature pyrolysis.

Influence of Interactions among Polymeric Components of Automobile Shredder Residue on the Pyrolysis Temperature and Characterization of Pyrolytic Products

Pyrolysis and gasification have gradually become the main means to dispose of automobile shredder residue (ASR), since these methods can reduce the volume and quality of landfill with lower cost and energy recovery can be conducted simultaneously. As the ASR pyrolysis process is integrated, the results of pyrolysis reactions of organic components and the interaction among polymeric components can be clarified by co-pyrolysis thermogravimetric experiments. The results show that the decomposition mechanisms of textiles and foam are markedly changed by plastic in the co-pyrolysis process, but the effect is not large for rubber and leather. This effect is mainly reflected in the pyrolysis temperature and pyrolysis rate. The pyrolytic trend and conversion curve shape of the studied ASR can be predicted by the main polymeric components with a parallel superposition model. The pyrolytic product yields and characterizations of gaseous products were analyzed in laboratory-scale non-isothermal pyrolysis experiments at finished temperatures of 500 °C, 600 °C, and 700 °C. The results prove that the yields of pyrolytic gas products are determined by the thermal decomposition of organic substances in the ASR and final temperature.

Thermogravimetric Kinetic Study of Automobile Shredder Residue (ASR) Pyrolysis

The separated and sorted combustibles from automobile shredder residue (ASR) can be pyrolyzed and used as a heat source or liquefied to produce materials with added value. In this study, the thermal decomposition properties of ASR were determined and thermal kinetic studies were performed. Four types of raw materials were separated from ASR and mixed at a constant ratio: 38.5 wt.% of plastic; 31.6 wt.% of fiber; 17.3 wt.% of sponge; and 12.3 wt.% of rubber. Pyrolysis kinetics analysis was carried out using the Thermogravimetric analysis-derivative thermogravimetry (TGA-DTG) technique and activation energy were calculated by differential and integral isoconversional model methods, Flynn-Wall-Ozawa (FWO), Kissinger-Akahira-Sunose (KAS), and Friedman. Thermogravimetric analysis was performed under nitrogen with four temperature rate conditions from room temperature to 800 °C. In the thermal degradation profile, peaks representing mass loss rates were observed for each sample at different temperature ranges. It was observed that the final mass reduction temperature in the mixed samples was lower than in the individual samples. The activation energies of plastics and rubbers were 105.39 kJ/mol and 115.20 kJ/mol respectively. The sponge foams and fibers were 172.59 kJ/mol and 160.30 kJ/mol respectively. The mixed sample had an activation energy value of 159.56 kJ/mol. The basic physicochemical and pyrolysis characteristics of ASR were examined to be used as basic data for the recycling of ASR for future pyrolysis.

Variability and Bias in Measurements of Metals Mass Fractions in Automobile Shredder Residue

The treatment of end-of-life vehicles generates large amounts of automobile shredder residue (ASR), a potential source of recycled metals. Reliable measurement methods are required to determine the composition of ASR and evaluate the resource potential. We reported on research undertaken to investigate bias and variability in the process of measuring trace metals in ASR. Two primary samples of shredder light fraction (SLF) underwent extensive physical sample preparation and chemical analysis. The samples were spiked to control random variations and systematic effects during physical sample preparation. Chemical analysis was conducted using wavelength-dispersive X-ray fluorescence spectrometry (WD-XRF), a fully validated wet-chemical analysis, and a wet-chemical analysis representing an “in-house” lab procedure. Physical sample preparation introduced deviations up to a factor of 2, likely due to preferential losses and heterogeneity. Deviations for WD-XRF measurements of elements were in the range +100%/−50%. In-house chemical analysis produced results that were in good agreement with validated results for Al, Fe and Sn, but led to biased results or high variability for Cd, Dy, La, Nd, Pb, Pd, Pt and Sb. To improve the chemical analysis of trace metals in SLF, we recommended reducing particle size to less than 0.1 mm before chemical analysis and using a larger number of repeated digestions.

Electrostatic Separation of Copper and Glass Particles in Pretreated Automobile Shredder Residue

There is increasing demand for an efficient technique for separating automobile shredder residue (ASR) obtained from end-of-life vehicles (ELVs). A particular challenge is the physical separation of conductive materials from glass. In this study, the performance of pretreatment and induction electrostatic separation process was evaluated. The results show that a sieving/washing (combination of sieving and washing) pretreatment was the most effective for removing conductive material compared to electrostatic separation alone. The optimum separation efficiency of copper products was achieved with an applied voltage of 20 kV, a relative humidity of less than 35%, and a splitter position of 8 cm. Although the separation efficiency was slightly reduced when some small glass particles remained attached to the conductive materials, the separation efficiency of copper from the pretreated ASR dramatically increased to 83.1% grade and 90.4% recovery, compared to that of raw ASR (34.3% grade and 58.6% recovery). Based on these results, it was demonstrated that the proposed sieving/washing pretreatment was proficient at removing conductive materials from glass; thus, it has the potential to significantly improve the efficiency of electrostatic separation for ASR.