carbonation of steel slag testing of the wet route in a pilot scale reactor

Abstract This work reports the first results of an on-going activity aimed at the scale up of the wet-route carbonation of steel slag for storing CO2 and generating a product with valorization potential. Two batches of Basic Oxygen Furnace slag (BOF1 and BOF2) collected at different times from a steelmaking plant downstream iron recovery were used to perform the tests in a pilot-scale rotary kiln unit part of ENEA's research infrastructure. The tests were carried out at ambient (25 °C- 37 °C) and enhanced temperature (45 °C-53 °C), under a 40-47% CO2 flow, at atmospheric pressure for a reaction time of 30 min. In each experiment around 1000-1500 g of BOF slag was employed. The residues were humidified in order to achieve a liquid to solid ratio of 0.17 l/kg. This value was selected on the basis of the results of preliminary lab-scale static and dynamic experiments that are also presented in this paper. The product collected at the end of each test was cured at controlled conditions (T=25 °C e RH=100%) for 28 days and then characterized in terms of particle size, CO2 uptake and environmental behavior. The mean diameter (D50) of the obtained product was around 1 mm for the tests performed at room temperature and slightly lower for the test performed at 50 °C, i.e. around twice the size of the starting material. The CO2 uptake measured for samples collected immediately after the tests was quite similar (4-6% wt.), whereas after curing a 50% increase was observed for all BOF1 slag samples, while only a slight increase was observed for BOF2 slag. These results are significantly higher than the ones of the lab-scale tests. The leaching behavior of the product appeared also to be significantly affected by the treatment performed in the pilot plant

An evaluation of copper biosorption by a brown seaweed under optimized conditions

A basic investigation into the removal of copper ions from aqueous solutions by Sargassum sp. was conducted in batch conditions. The influence of different experimental parameters such as initial pH, shaking rate, sorption time, temperature, equilibrium conditions and initial concentrations of copper ions on copper uptake was evaluated. Results indicated that for shaking rates higher than 100 rpm no significant changes in copper accumulation were observed, as well as for pH values between 3.0 and 5.0. No marked effect on the biosorption of copper was detected for temperatures between 298 and 328K. The Langmuir model better represented the sorption process, in comparison to the model of Freundlich. The process followed a second-order kinetics and its calculated activation energy was 5.2 kcal/mol. Due to its outstanding copper uptake capacity (1.48 mmol/g biomass) Sargassum sp. proved to be an excellent biomaterial for accumulating and recovering copper from industrial solutions

Análise de Risco: estado da arte da metodologia Hazop generalizada, aplicações e perspectivas na indústria de processos

Introduction: The Hazard and Operability Study is considered a feasible tool to assess risks, where complex technologies, require new strategies to guarantee efficiency, safety, and quality of products. Objective: To perform a Hazop publications review, to establish the state of the art, current procedures and perspectives in the pharmaceutical industry. Method: Hazop methodology and improvements to satisfy actual needs were structured. Subsequently, its application and integration with other risk tools, and experts systems, were analyzed to define the current approach and future perspectives. Results: The review allowed the understanding where models, simulations and specialized software offered adequate support to assess risk in current complex processes. In addition, an efficient definition of causes and consequences depends of expert systems, where simulations acquire experience through the creation of databases, reducing the need of specific process knowledge, which is a typical limitation of the conventional Hazop methodology. Conclusions: A review of the Hazop stateof- the-art highlighted the importance to assess risks within the process industry. However, the use of new technologies designed to meet regulatory affairs to guarantee safety and quality principles would require the ongoing improvement of the Hazop methodology, restricting the dependence of specialists, and increasing the use of expert systems.Introducción: El Estudio de Riesgos y Operabilidad se considera una herramienta factible para evaluar los riesgos, cuando las tecnologías complejas requieren nuevas estrategias para garantizar la eficiencia, la seguridad y la calidad de los productos. Objetivo: realizar una revisión de las publicaciones de Hazop, para establecer el estado del arte, los procedimientos actuales y las perspectivas en la industria farmacéutica. Método: fue estructurada la metodología Hazop y las mejoras para satisfacer las necesidades reales. Posteriormente, se analizó su aplicación e integración con otras herramientas de riesgo y sistemas de expertos para definir el enfoque actual y las perspectivas futuras. Resultados: la revisión permitió comprender dónde los modelos, las simulaciones y el software especializado ofrecían el soporte adecuado para evaluar el riesgo en los procesos complejos actuales. Además, una definición eficiente de causas y consecuencias depende de los sistemas expertos, donde las simulaciones adquieren experiencia a través de la creación de bases de datos, lo que reduce la necesidad de un conocimiento específico del proceso, que es una limitación típica de la metodología convencional Hazop. Conclusiones: una revisión del estado del arte de Hazop resaltó la importancia de evaluar los riesgos dentro de la industria de procesos. Sin embargo, el uso de nuevas tecnologías diseñadas para cumplir con los asuntos regulatorios para garantizar los principios de seguridad y calidad requeriría la mejora continua de la metodología Hazop, restringiendo la dependencia de especialistas y aumentando el uso de sistemas expertos.Título PT: Análise de Risco: estado da arte da metodologia Hazop generalizada, aplicações e perspectivas na indústria de processos Introdução: O Estudo de Perigos e Operabilidade (Hazop) é considerado uma ferramenta para avaliação de riscos, na qual tecnologias complexas exigem novas estratégias para garantir a eficiência, a segurança e a qualidade dos produtos. Objetivo: Realizar uma revisão de publicações do Hazop, para estabelecer o estado da arte, os procedimentos e as suas perspectivas na indústria farmacêutica. Método: O procedimento Hazop e suas adequações para satisfazer as necessidades atuais foram estruturados. Posteriormente, aplicações e integração com outras ferramentas de risco e sistemas expertos foram analisadas para definir a abordagem atual e perspectivas futuras. Resultados: A revisão permitiu a compreensão de que modelos, simulações e software especializado oferecem suporte para avaliar riscos em processos complexos. Adicionalmente, a correta definição de causas e consequências depende do uso de sistemas expertos, cujas simulações adquirem experiência através da criação de bancos de dados, reduzindo a necessidade de conhecimento específico do processo, que é uma limitação da metodologia Hazop convencional. Conclusões: A revisão do estado da arte do Hazop destacou a importância de avaliar riscos dentro da indústria de processos. No entanto, novas tecnologias utilizadas para atender quesitos regulatórios de segurança e qualidade precisam da melhoria contínua da metodologia Hazop, reduzindo a dependência de especialista por meio do uso de sistemas especializados

Batch and fixed-bed column biosorption of manganese ion by Sargassum filipendula

This paper presents experimental data of the biosorption of manganese onto Sargassum filipendula in both batch and fixed-bed column systems. Batch equilibrium data were used for nonlinear fittings of the Langmuir and Freundlich isotherms. A mathematical model based on mass balances in the fluid and in the sorbent was applied to represent the experimental fixed-bed column data. The utilization of isotherm parameters from the batch experiments in the breakthrough model implied a significant mismatch in relation to the laboratory data. Alternatively, additional fixed-bed column data provided new parameters for the isotherm evaluation, and the corresponding simulated profile of the breakthrough curve reached better agreement to the experimental results

Kinetics and equilibrium of lanthanum biosorption by free and immobilized microalgal cells

This work aimed to study the potential for bioremediation of lanthanum by microalgae Ankistrodesmus sp. and Golenkinia sp., as free cells and immobilized in calcium alginate pellets. To reach that goal, studies have been conducted in batch and in continuous fixed bed column. Kinetic models of pseudo-first order and -second order and equilibrium isotherms of Langmuir and Freundlich were used to predict the metal accumulation behavior by free and immobilized biomass in a batch system. The data were best fit to kinetic model of second order, with coefficients of determination (R 2 ) greater than 0.98. Free cells were more efficient in the process than alginate pellets and it was not possible to model the results due to the very fast uptake. Equilibrium modelling indicated that both free and immobilized cells, as well as alginate pellets results were best fit to Langmuir equation due to the high R 2 value and similarity with experimental results. Dynamic column tests conducted with Ankistrodesmus sp. and Golenkinia sp. immobilized cells during 8 hours presented 80% efficiency in the removal of the metal, without reaching saturation. The high and fast ability of the microalgae to adsorb lanthanum corroborates their potential large-scale application