Antarctic Volcanic Flux Ratios from Law Dome Ice Cores

Explosive volcanic eruptions can inject large quantities of sulphur dioxide into the stratosphere. The aerosols that result from oxidation of the sulphur dioxide can produce significant cooling of the troposphere by reflecting or absorbing solar radiation. It is possible to obtain an estimate of the relative stratospheric sulphur aerosol concentration produced by different volcanoes by comparing sulphuric acid fluxes determined by analysis of polar ice cores. Here, we use a non-sea-salt sulphate time series derived from three well-dated Law Dome ice cores to investigate sulphuric acid flux ratios for major eruptions over the period AD 1301-1995. We use additional data from other cores to investigate systematic spatial variability in the ratios. Only for the Kuwae eruption (Law Dome ice date AD 1459.5) was the H2SO4 flux larger than that deposited by Tambora (Law Dome ice date AD 1816.7).

Tratamiento con ácido sulfúrico de semillas de la acacia blanca (Robinia pseudo acacia L.) cosechadas en Mendoza

The results obtained in germination test with seeds of "black locust" (Robinia Pseudo Acacia L) previously treated with sulphuric acid concentrated (d. 1.84) are given. Those test were made in order to get a good germination considering the water tight seed coat that those seeds have in a great percentage. The seeds were soaked in the solution for some minutes; the 180 and 210 minutes soaking (90 and 86.5 % respectively) gave the highest percentage and the fasted process of germination, which were higher than those obtained as efective by other researches. The test made would constitute another evidence of the effect of the locality of production upon the degree of water tightness of the Black locust seeds. The author suggests that the previous treatments of the seeds, the rusticity and quick growing of this species and the furrow system of irrigation so common in the zone will enable, perhaps with success the stablishment of woods of this valuable forestal species, by direct seeding.

Improved ore processing assessed by digital image análisis of the ores: a key to the sustainable development of the Iberian Pyrite Belt

Mining in the Iberian Pyrite Belt (IPB), the biggest VMS metallogenetic province known in the world to date, has to face a deep crisis in spite of the huge reserves still known after ≈5 000 years of production. This is due to several factors, as the difficult processing of complex Cu-Pb-Zn-Ag- Au ores, the exhaustion of the oxidation zone orebodies (the richest for gold, in gossan), the scarce demand for sulphuric acid in the world market, and harder environmental regulations. Of these factors, only the first and the last mentioned can be addressed by local ore geologists. A reactivation of mining can therefore only be achieved by an improved and more efficient ore processing, under the constraint of strict environmental controls. Digital image analysis of the ores, coupled to reflected light microscopy, provides a quantified and reliable mineralogical and textural characterization of the ores. The automation of the procedure for the first time furnishes the process engineers with real-time information, to improve the process and to preclude or control pollution; it can be applied to metallurgical tailings as well. This is shown by some examples of the IPB.

Aprovechamiento térmico de residuos estériles de carbón para generación eléctrica mediante tecnologías de combustión y gasificación eficientes y con mínimo impacto ambiental

La presente tesis doctoral, “Aprovechamiento térmico de residuos estériles de carbón para generación eléctrica mediante tecnologías de combustión y gasificación eficientes y con mínimo impacto ambiental”, desarrolla la valorización energética de los residuos del carbón, estériles de carbón, producidos durante las etapas de extracción y lavado del carbón. El sistema energético se encuentra en una encrucijada, estamos asistiendo a un cambio en el paradigma energético y, en concreto, en el sector de la generación eléctrica. Se precipita un cambio en la generación y el consumo eléctricos. Una mayor concienciación por la salud está forzando la contención y eliminación de agentes contaminantes que se generan por la utilización de combustibles fósiles de la forma en la que se viene haciendo. Aumenta la preocupación por el cambio climático y por contener en 2°C el aumento de la temperatura de la Tierra para final de este siglo, circunstancia que está impulsando el desarrollo e implantación definitiva de tecnología de control y reducción de emisiones CO2. Generar electricidad de una manera sostenible se está convirtiendo en una obligación. Esto se materializa en generar electricidad respetando el medioambiente, de una forma eficiente en la utilización de los recursos naturales y a un coste competitivo, pensando en el desarrollo de la sociedad y en el beneficio de las personas. En la actualidad, el carbón es la principal fuente de energía utilizada para generar electricidad, y su empleo presenta la forma de energía más barata para mejorar el nivel de vida de cualquier grupo y sociedad. Además, se espera que el carbón siga presente en el mix de generación eléctrica, manteniendo una significativa presencia y extrayéndose en elevadas cantidades. Pero la producción de carbón lleva asociada la generación de un residuo, estéril, que se produce durante la extracción y el lavado del mineral de carbón. Durante décadas se ha estudiado la posibilidad de utilizar el estéril y actualmente se utiliza, en un limitado porcentaje, en la construcción de carreteras, terraplenes y rellenos, y en la producción de algunos materiales de construcción. Esta tesis doctoral aborda la valorización energética del estéril, y analiza el potencial aprovechamiento del residuo para generar electricidad, en una instalación que integre tecnología disponible para minimizar el impacto medioambiental. Además, persigue aprovechar el significativo contenido en azufre que presenta el estéril para producir ácido sulfúrico (H2SO4) como subproducto de la instalación, un compuesto químico muy demandado por la industria de los fertilizantes y con multitud de aplicaciones en otros mercados. Se ha realizado el análisis de caracterización del estéril, los parámetros significativos y los valores de referencia para su empleo como combustible, encontrándose que su empleo como combustible para generar electricidad es posible. Aunque en España se lleva extrayendo carbón desde principios del siglo XVIII, se ha evaluado para un período más reciente la disponibilidad del recurso en España y la normativa existente que condiciona su aplicación en el territorio nacional. Para el período evaluado, se ha calculado que podrían estar disponibles más de 68 millones de toneladas de estéril susceptibles de ser valorizados energéticamente. Una vez realizado el análisis de la tecnología disponible y que podría considerarse para emplear el estéril como combustible, se proponen cuatro configuraciones posibles de planta, tres de ellas basadas en un proceso de combustión y una de ellas en un proceso de gasificación. Tras evaluar las cuatro configuraciones por su interés tecnológico, innovador y económico, se desarrolla el análisis conceptual de una de ellas, basada en un proceso de combustión. La instalación propuesta tiene una capacidad de 65 MW y emplea como combustible una mezcla de carbón y estéril en relación 20/80 en peso. La instalación integra tecnología para eliminar en un 99,8% el SO2 presente en el gas de combustión y en más de un 99% las partículas generadas. La instalación incorpora una unidad de producción de H2SO4, capaz de producir 18,5 t/h de producto, y otra unidad de captura para retirar un 60% del CO2 presente en la corriente de gases de combustión, produciendo 48 tCO2/h. La potencia neta de la planta es 49,7 MW. Se ha calculado el coste de inversión de la instalación, y su cálculo resulta en un coste de inversión unitario de 3.685 €/kW. ABSTRACT The present doctoral thesis, “Thermal utilisation of waste coal for electricity generation by deployment of efficient combustion and gasification technologies with minimum environmental impact”, develops an innovative waste-to-energy concept of waste coals produced during coal mining and washing. The energy system is at a dilemma, we are witnessing a shift in the energy paradigm and specifically in the field of electricity generation. A change in the generation and electrical consumption is foreseen. An increased health consciousness is forcing the containment and elimination of pollutants that are generated by the use of fossil fuels in the way that is being done. Increasing concern about climate change and to contain the rise of global temperature by 2°C by the end of this century, is promoting the development and final implementation of technology to control and reduce the CO2 emission. Electricity generation in a sustainable manner is becoming an obligation. This concept materialised in generating electricity while protecting the environment and deployment of natural resources at a competitive cost, considering the development of society and people´s benefit. Currently, coal is the main source of energy employ to generate electricity, and its use represents the most cost competitive form of energy to increase the standard of living of any group or society. Moreover, coal will keep playing a key role in the global electricity generation mix, maintaining a significant presence and being extracting in large amounts. However, coal production implies the production of waste, termed waste coal or culm in Pennsylvania anthracite extraction, produced during coal mining and coal washing activities. During the last decades, the potential use of waste coal has been studied, and currently, in a limited amount, waste coal is used in roads construction, embankments and fillings, and to produce some construction materials. This doctoral thesis evaluates the waste to energy of waste coals and assesses its potential use to generate electricity, implementing available technology to minimise the environment impact. Additionally, it pursues the significant advantage that presents sulphur content in waste coal to produce sulphuric acid (H2SO4) as a byproduct of the waste-to-energy process, a chemical compound highly demanded by the fertiliser industry and many applications in other markets. It analyses the characteristics of waste coal, and assesses the significant parameters and reference values for its use as fuel, being its fuel use for electricity generation very possible. While mining coal is taking place in Spain since the 1700s, it has been evaluated for a more recent period the waste coal available in Spain and the existing legislation that affects its application and deploy to generate electricity in the country. For the evaluation period has been calculated that may be available more than 68 million tons of waste coal that can be waste-toenergy. The potential available technology to deploy waste coal as fuel has been evaluated and assessed. After considering this, the doctoral thesis proposes four innovative alternatives of facility configuration, three of them based on a combustion process and one in a gasification process. After evaluating the four configurations for its technological, innovative and economic interest, the conceptual analysis of one of alternatives, based on a combustion process, takes place. The proposed alternative facility developed has a capacity of 65 MW, using as fuel a mixture of coal and waste coal 80/20 by weight. The facility comprises technology to remove 99.8% SO2 present in the flue gas and more than 99% of the particles. The facility includes a unit capable of producing 18.5 t/h of H2SO4, and another capture facility, removing 60% of CO2 present in the flue gas stream, producing 48 tCO2/h. The net capacity of the power station is 49.7 MW. The facility unitary cost of investment is 3,685 €/kW.

Avaliação da influência do efeito de ultrassom na lixiviação de metais de placas de circuito impresso obsoletas.

Os equipamentos elétricos e eletrônicos (EEE) possuem uma grande importância na sociedade contemporânea, e estão presentes no cotidiano das pessoas de forma ubíqua. Com o aumento no consumo de EEE juntamente com a obsolescência precoce, surge um novo tipo de resíduo, chamado de Resíduos de Equipamentos Elétricos e Eletrônicos (REEE). Os REEE não devem ser descartados em aterros, pelo risco de contaminação e pelo desperdício de material. Assim, a reciclagem se faz necessária. As placas de circuito impresso (PCI) estão presentes na grande maioria do REEE e contem a maior variedade de metais, incluindo metais valiosos como Au, Ag, Pt e Cu. A complexidade torna a reciclagem destas placas muito difícil. Rotas hidrometalúrgicas tem surgido como uma alternativa mais limpa para o tratamento de PCI, em detrimento aos processos pirometalúrgicos. Nas rotas hidrometalúrgicas, os metais são extraídos pela lixiviação realizada por ácidos ou bases. O efeito ultrassônico tem sido empregado na síntese de novas substâncias e também em alguns casos no tratamento de resíduos. O processo central no uso de ultrassom é a cavitação acústica, capaz de produzir microbolhas na solução com temperatura da ordem de 5000 K e pressão de 500 atm localmente. Além disto, a implosão das bolhas de cavitação em meio heterogêneo causa um jato de solução na superfície, que pode alcançar velocidade de 100 m.s-1. Assim, esta tese tem como objetivo a investigação do efeito do ultrassom sobre PCI obsoletas. Dois efeitos foram investigados: o efeito da cominuição das PCI promovido pela cavitação e a influência da cavitação na lixiviação com ácido sulfúrico de Fe, Al e Ni. Os parâmetros investigados na cominuição foram: tipo de placa, granulometria da placa moída e potência de ultrassom. Os parâmetros de lixiviação avaliados foram: razão sólido-líquido (S/L), concentração de ácido e potência de ultrassom. Também foram realizados ensaios de lixiviação sonicados com meio oxidante. Foi feita a análise cinética para se determinar qual é o controle da reação de lixiviação.

Synthesis of glycerol-based carbon materials as environmental application

Crude glycerol, obtained from the biodiesel production, is actually an abundant and low-cost feedstock, making the preparation of carbonaceous materials by partial carbonization and sulfonation of this by-product an interesting research focus. Bearing this in mind, the aim of this study is to explore several types of glycerol-based carbon materials synthesized by partial carbonization of glycerol in concentrated sulphuric acid solution for the removal of flumequine and tetracycline from aqueous solutions. This study is focused on the synthesis and application of glycerol-based carbon materials as adsorbents for the removal of the antibiotic compounds flumequine and tetracycline from aqueous solution. The different synthesized materials were labelled as GBCM followed by a subscript number corresponding to the activation temperature in oC (i.e., GBCM200, GBCM300, and GBCM350)