Fabian Diaz | RWTH Aachen University (original) (raw)

Papers by Fabian Diaz

CT&F - Ciencia, Tecnología y Futuro

Se propone un modelo amatemático para la simulación de hornos de refinería. Consta de dos submode... more Se propone un modelo amatemático para la simulación de hornos de refinería. Consta de dos submodelos diferentes, uno para el lado del proceso y otro para el lado de los gases de combustión. El lado del proceso se modela adecuadamente como un flujo de tapón debido a la alta velocidad del fluido dentro de los tubos. El lado de los gases de combustión está compuesto por una cámara radiativa y una sección convectiva, ambas conectadas por una zona de tubo de escudo. Ambos modelos están conectados por la temperatura de la superficie del tubo. Como el modelo del lado de los gases de combustión utiliza esta temperatura como datos de entrada, el modelo del lado del proceso recalcula esta temperatura. El procedimiento se ejecuta hasta que se alcanza cierta tolerancia. Este modelo matemático ha demostrado ser una herramienta útil para el análisis y la simulación de hornos.

An optimized recycling route is being designed to recycle complex metallic materials such as wast... more An optimized recycling route is being designed to recycle complex metallic materials such as waste electric and electronic equipment (WEEE). The new proposed methodology overcomes huge challenges like improved recovery of valuable metals, better control of hazardous substances, improved process control and recycling capacity. The recycling process for E-Scrap would be developed in such way that no waste would be obtained and all products and by-products could be saleable materials. In this work pyrolysis is introduced as a pre-processing method, which stands out among current standard processing paths due to its versatility when treating two different streams from high metal containing WEEE. From one side the method achieves a better separation of the metallic from the non-metallic fraction when dealing with PCBs. An increase of 10% in the beneficiation of the metal, while the production of solid and a liquid of organic nature, with high potential as fuel and chemical feedstock are valuable characteristics. Alternatively, it favours the separation of plastic material found in the metallic fraction as a requirement to a farther separation in order to produce individual fractions rich in Cu and Al with purities above 90%.

As a result of increasing demands for aluminium in numerous sectors such as construction, automot... more As a result of increasing demands for aluminium in numerous sectors such as construction, automotive and transportation, its rate of consumption has sharply risen in recent decades. Aluminium is also used in containers for food- and drinks packaging due to its good formability, low density and corrosion resistance. The use of aluminium in everyday products lead to complex end-of-life waste, such as coffee capsules, requiring advanced recycling processes to achieve high metal recovery and quality, which is essential to reduce environmental impact and economic cost. This study focuses on the recyclability of used coffee capsules via remelting under a salt flux. Results were evaluated for different aspects such as metal yield, metal purity as well as gas generation during treatment.

The WEEE directive 2002/86/EG defined WEEE as the end-of-life products from electrical and electr... more The WEEE directive 2002/86/EG defined WEEE as the end-of-life products from electrical and electronic equipment (EEE) [1]. Waste from electrical and electronic equipment is one of the fastest growing wastes in Europe (3 to 5 % per year) and it is expected to be increased to 12.3 mill. t by 2020 [2, 3]. According to estimates, at least 20 to 50 mill. t of electrical and electronic equipment are produced annually worldwide [4]. WEEE can be defined as a complex mixture of different materials and components with important presence of hazardous substances, which demands proper management to avoid environmental and health problems. In addition, it is estimated that an important amount of resources (e.g. 10 % of the gold production, https://ec.europa.eu/environment/waste/ weee/index_en.htm) are spent in the fabrication of electronic equipment. Therefore, it is not only the considerable amount of scraps to be processed but also the importance of developing an effective handling in terms of ...

Metals, 2018

Recycling of Li-Ion Batteries (LIBs) is still a topic of scientific interest. Commonly, spent LIB... more Recycling of Li-Ion Batteries (LIBs) is still a topic of scientific interest. Commonly, spent LIBs are pretreated by mechanical and/or thermal processing. Valuable elements are then recycled via pyrometallurgy and/or hydrometallurgy. Among the thermal treatments, pyrolysis is the most commonly used pre-treatment process. This work compares the treatment of typical cathode nickel-cobalt-aluminum (NCA) material by conventional pyrolysis, and by a microwave assisted pyrolysis. In the conventional route, the heating is provided indirectly, while via microwave the heating is absorbed by the microwaves, according to the materials properties. The comparison is done with help of a detailed characterization of solid as well as the gaseous products during and after the thermal treatment. The results indicated at least three common stages in the degradation: Dehydration and evaporation of electrolyte solvents (EC) and two degradation periods of EC driven by combustion and reforming reactions. ...

Journal of Sustainable Metallurgy, 2018

Despite the high number of publications regarding pyrolysis of electronic scraps, there have not ... more Despite the high number of publications regarding pyrolysis of electronic scraps, there have not been many attempts to correctly understand the degradation mechanisms of organics. Hence, it is a challenge to identify the optimum parameters that can benefit its metallurgical recycling and especially the recovery of technological elements. This article refers to a detailed analysis of the degradation mechanisms during slow pyrolysis as well as its deflection under fast heating speed. The analysis was made based on continuous off-gas analysis by Fourier transform infrared spectroscopy (FTIR), kinetic analysis on slow pyrolysis and measurement of total carbon (TC), total organic carbon (TOC), and elemental carbon (EC) in solid products at different pyrolysis temperatures. Results have evidenced that degradation of organics in pyrolysis of PCBs takes place in at least three different stages, which are driven by different reaction mechanisms and kinetic conditions. In addition, fast pyrolysis has shown to be beneficial if operated above 600°C, where high-quality syngas is produced, containing elevated concentrations of CH 4 and H 2 , and a lower concentration of H 2 O (g) compared to conventional pyrolysis and fast pyrolysis at lower temperatures.

Waste Management, 2019

Recycling of Li-ion batteries (LIBs) is becoming an urgent issue. However, the chemical compositi... more Recycling of Li-ion batteries (LIBs) is becoming an urgent issue. However, the chemical composition and the hazard of off-gas produced during the recycling process still remain unclarified due to the complicated reactions during thermal runaway (TR). In order to meet the legislative requirements to carry out an environmentally friendly recycling, this manuscript aims to undertake quantitative analysis and toxicity evaluation of the off-gas produced in mechanical treatment and thermal treatment of LIBs. The measurements were carried out by online Fourier transform infrared spectroscopy (FTIR) and ion chromatograph (IC). The volume of total off-gas was calculated and its toxicity was evaluated by USA's Protective Action Criteria. The influences of treatment method, state-of-charge (SOC), atmosphere, and type of cathode were investigated.

Chemie Ingenieur Technik, 2015

In the past years the topic of WEEE recycling has gained more relevance due to increased producti... more In the past years the topic of WEEE recycling has gained more relevance due to increased production and reduced effectiveness in metal recovery. Therefore, new processing technologies are evolving today as result of the increasing heterogeneity of WEEE. Such is the case of pyrolysis as an upgrading and conditioning method for different types of complex scraps, which also facilitate further mechanical separation of metal as well as production of an alternative fuel source. In this work, it has been concluded that pyrolysis can be easily integrated as a preprocessing step in a resource efficient recycling route.

CT&F - Ciencia, Tecnología y Futuro

Se propone un modelo amatemático para la simulación de hornos de refinería. Consta de dos submode... more Se propone un modelo amatemático para la simulación de hornos de refinería. Consta de dos submodelos diferentes, uno para el lado del proceso y otro para el lado de los gases de combustión. El lado del proceso se modela adecuadamente como un flujo de tapón debido a la alta velocidad del fluido dentro de los tubos. El lado de los gases de combustión está compuesto por una cámara radiativa y una sección convectiva, ambas conectadas por una zona de tubo de escudo. Ambos modelos están conectados por la temperatura de la superficie del tubo. Como el modelo del lado de los gases de combustión utiliza esta temperatura como datos de entrada, el modelo del lado del proceso recalcula esta temperatura. El procedimiento se ejecuta hasta que se alcanza cierta tolerancia. Este modelo matemático ha demostrado ser una herramienta útil para el análisis y la simulación de hornos.

An optimized recycling route is being designed to recycle complex metallic materials such as wast... more An optimized recycling route is being designed to recycle complex metallic materials such as waste electric and electronic equipment (WEEE). The new proposed methodology overcomes huge challenges like improved recovery of valuable metals, better control of hazardous substances, improved process control and recycling capacity. The recycling process for E-Scrap would be developed in such way that no waste would be obtained and all products and by-products could be saleable materials. In this work pyrolysis is introduced as a pre-processing method, which stands out among current standard processing paths due to its versatility when treating two different streams from high metal containing WEEE. From one side the method achieves a better separation of the metallic from the non-metallic fraction when dealing with PCBs. An increase of 10% in the beneficiation of the metal, while the production of solid and a liquid of organic nature, with high potential as fuel and chemical feedstock are valuable characteristics. Alternatively, it favours the separation of plastic material found in the metallic fraction as a requirement to a farther separation in order to produce individual fractions rich in Cu and Al with purities above 90%.

As a result of increasing demands for aluminium in numerous sectors such as construction, automot... more As a result of increasing demands for aluminium in numerous sectors such as construction, automotive and transportation, its rate of consumption has sharply risen in recent decades. Aluminium is also used in containers for food- and drinks packaging due to its good formability, low density and corrosion resistance. The use of aluminium in everyday products lead to complex end-of-life waste, such as coffee capsules, requiring advanced recycling processes to achieve high metal recovery and quality, which is essential to reduce environmental impact and economic cost. This study focuses on the recyclability of used coffee capsules via remelting under a salt flux. Results were evaluated for different aspects such as metal yield, metal purity as well as gas generation during treatment.

The WEEE directive 2002/86/EG defined WEEE as the end-of-life products from electrical and electr... more The WEEE directive 2002/86/EG defined WEEE as the end-of-life products from electrical and electronic equipment (EEE) [1]. Waste from electrical and electronic equipment is one of the fastest growing wastes in Europe (3 to 5 % per year) and it is expected to be increased to 12.3 mill. t by 2020 [2, 3]. According to estimates, at least 20 to 50 mill. t of electrical and electronic equipment are produced annually worldwide [4]. WEEE can be defined as a complex mixture of different materials and components with important presence of hazardous substances, which demands proper management to avoid environmental and health problems. In addition, it is estimated that an important amount of resources (e.g. 10 % of the gold production, https://ec.europa.eu/environment/waste/ weee/index_en.htm) are spent in the fabrication of electronic equipment. Therefore, it is not only the considerable amount of scraps to be processed but also the importance of developing an effective handling in terms of ...

Metals, 2018

Recycling of Li-Ion Batteries (LIBs) is still a topic of scientific interest. Commonly, spent LIB... more Recycling of Li-Ion Batteries (LIBs) is still a topic of scientific interest. Commonly, spent LIBs are pretreated by mechanical and/or thermal processing. Valuable elements are then recycled via pyrometallurgy and/or hydrometallurgy. Among the thermal treatments, pyrolysis is the most commonly used pre-treatment process. This work compares the treatment of typical cathode nickel-cobalt-aluminum (NCA) material by conventional pyrolysis, and by a microwave assisted pyrolysis. In the conventional route, the heating is provided indirectly, while via microwave the heating is absorbed by the microwaves, according to the materials properties. The comparison is done with help of a detailed characterization of solid as well as the gaseous products during and after the thermal treatment. The results indicated at least three common stages in the degradation: Dehydration and evaporation of electrolyte solvents (EC) and two degradation periods of EC driven by combustion and reforming reactions. ...

Journal of Sustainable Metallurgy, 2018

Despite the high number of publications regarding pyrolysis of electronic scraps, there have not ... more Despite the high number of publications regarding pyrolysis of electronic scraps, there have not been many attempts to correctly understand the degradation mechanisms of organics. Hence, it is a challenge to identify the optimum parameters that can benefit its metallurgical recycling and especially the recovery of technological elements. This article refers to a detailed analysis of the degradation mechanisms during slow pyrolysis as well as its deflection under fast heating speed. The analysis was made based on continuous off-gas analysis by Fourier transform infrared spectroscopy (FTIR), kinetic analysis on slow pyrolysis and measurement of total carbon (TC), total organic carbon (TOC), and elemental carbon (EC) in solid products at different pyrolysis temperatures. Results have evidenced that degradation of organics in pyrolysis of PCBs takes place in at least three different stages, which are driven by different reaction mechanisms and kinetic conditions. In addition, fast pyrolysis has shown to be beneficial if operated above 600°C, where high-quality syngas is produced, containing elevated concentrations of CH 4 and H 2 , and a lower concentration of H 2 O (g) compared to conventional pyrolysis and fast pyrolysis at lower temperatures.

Waste Management, 2019

Recycling of Li-ion batteries (LIBs) is becoming an urgent issue. However, the chemical compositi... more Recycling of Li-ion batteries (LIBs) is becoming an urgent issue. However, the chemical composition and the hazard of off-gas produced during the recycling process still remain unclarified due to the complicated reactions during thermal runaway (TR). In order to meet the legislative requirements to carry out an environmentally friendly recycling, this manuscript aims to undertake quantitative analysis and toxicity evaluation of the off-gas produced in mechanical treatment and thermal treatment of LIBs. The measurements were carried out by online Fourier transform infrared spectroscopy (FTIR) and ion chromatograph (IC). The volume of total off-gas was calculated and its toxicity was evaluated by USA's Protective Action Criteria. The influences of treatment method, state-of-charge (SOC), atmosphere, and type of cathode were investigated.

Chemie Ingenieur Technik, 2015

In the past years the topic of WEEE recycling has gained more relevance due to increased producti... more In the past years the topic of WEEE recycling has gained more relevance due to increased production and reduced effectiveness in metal recovery. Therefore, new processing technologies are evolving today as result of the increasing heterogeneity of WEEE. Such is the case of pyrolysis as an upgrading and conditioning method for different types of complex scraps, which also facilitate further mechanical separation of metal as well as production of an alternative fuel source. In this work, it has been concluded that pyrolysis can be easily integrated as a preprocessing step in a resource efficient recycling route.