Production of Mg(OH)2 from Mg-silicate rock for CO2 mineral sequestration

Sequestration of carbon dioxide in mineral rocks, also known as CO2 Capture and Mineralization (CCM), is considered to have a huge potential in stabilizing anthropogenic CO2 emissions. One of the CCM routes is the ex situ indirect gas/sold carbonation of reactive materials, such as Mg(OH)2, produced from abundantly available Mg-silicate rocks. The gas/solid carbonation method is intensively researched at Åbo Akademi University (ÅAU ), Finland because it is energetically attractive and utilizes the exothermic chemistry of Mg(OH)2 carbonation. In this thesis, a method for producing Mg(OH)2 from Mg-silicate rocks for CCM was investigated, and the process efficiency, energy and environmental impact assessed. The Mg(OH)2 process studied here was first proposed in 2008 in a Master’s Thesis by the author. At that time the process was applied to only one Mg-silicate rock (Finnish serpentinite from the Hitura nickel mine site of Finn Nickel) and the optimum process conversions, energy and environmental performance were not known. Producing Mg(OH)2 from Mg-silicate rocks involves a two-staged process of Mg extraction and Mg(OH)2 precipitation. The first stage extracts Mg and other cations by reacting pulverized serpentinite or olivine rocks with ammonium sulfate (AS) salt at 400 - 550 oC (preferably < 450 oC). In the second stage, ammonia solution reacts with the cations (extracted from the first stage after they are leached in water) to form mainly FeOOH, high purity Mg(OH)2 and aqueous (dissolved) AS. The Mg(OH)2 process described here is closed loop in nature; gaseous ammonia and water vapour are produced from the extraction stage, recovered and used as reagent for the precipitation stage. The AS reagent is thereafter recovered after the precipitation stage. The Mg extraction stage, being the conversion-determining and the most energy-intensive step of the entire CCM process chain, received a prominent attention in this study. The extraction behavior and reactivity of different rocks types (serpentinite and olivine rocks) from different locations worldwide (Australia, Finland, Lithuania, Norway and Portugal) was tested. Also, parametric evaluation was carried out to determine the optimal reaction temperature, time and chemical reagent (AS). Effects of reactor types and configuration, mixing and scale-up possibilities were also studied. The Mg(OH)2 produced can be used to convert CO2 to thermodynamically stable and environmentally benign magnesium carbonate. Therefore, the process energy and life cycle environmental performance of the ÅAU CCM technique that first produces Mg(OH)2 and the carbonates in a pressurized fluidized bed (FB) were assessed. The life cycle energy and environmental assessment approach applied in this thesis is motivated by the fact that the CCM technology should in itself offer a solution to what is both an energy and environmental problem. Results obtained in this study show that different Mg-silicate rocks react differently; olivine rocks being far less reactive than serpentinite rocks. In summary, the reactivity of Mg-silicate rocks is a function of both the chemical and physical properties of rocks. Reaction temperature and time remain important parameters to consider in process design and operation. Heat transfer properties of the reactor determine the temperature at which maximum Mg extraction is obtained. Also, an increase in reaction temperature leads to an increase in the extent of extraction, reaching a maximum yield at different temperatures depending on the reaction time. Process energy requirement for producing Mg(OH)2 from a hypothetical case of an iron-free serpentine rock is 3.62 GJ/t-CO2. This value can increase by 16 - 68% depending on the type of iron compound (FeO, Fe2O3 or Fe3O4) in the mineral. This suggests that the benefit from the potential use of FeOOH as an iron ore feedstock in iron and steelmaking should be determined by considering the energy, cost and emissions associated with the FeOOH by-product. AS recovery through crystallization is the second most energy intensive unit operation after the extraction reaction. However, the choice of mechanical vapor recompression (MVR) over the “simple evaporation” crystallization method has a potential energy savings of 15.2 GJ/t-CO2 (84 % savings). Integrating the Mg(OH)2 production method and the gas/solid carbonation process could provide up to an 25% energy offset to the CCM process energy requirements. Life cycle inventory assessment (LCIA) results show that for every ton of CO2 mineralized, the ÅAU CCM process avoids 430 - 480 kg CO2. The Mg(OH)2 process studied in this thesis has many promising features. Even at the current high energy and environmental burden, producing Mg(OH)2 from Mg-silicates can play a significant role in advancing CCM processes. However, dedicated future research and development (R&D) have potential to significantly improve the Mg(OH)2 process performance.

AC luettelo

kuv., 21 x 28 cm

Uso do fixador esquelético externo Tipo II para osteossíntese de tibiotarso em galinhas da raça Plymouth Rock Branca: modelo experimental para uso em aves selvagens

Foi avaliada a eficiência do fixador esquelético externo Tipo II para o tratamento de fratura de tibiotarso em oito galinhas adultas da raça Plymouth Rock Branca. As aves foram pré-medicadas com sulfato de morfina e anestesiadas com halotano. Em seguida, foi realizada osteotomia na diáfise do tibiotarso esquerdo, por meio de serra oscilatória. Quatro pinos de Kirschner foram inseridos através das corticais ósseas, dois proximalmente e dois distalmente ao foco da fratura. Após a redução desta, as extremidades dos dois pinos proximais e distais foram torcidas em direção distal ou proximal, respectivamente, sendo os pinos conectados externamente por meio de duas barras de acrílico autopolimerizável, nas faces lateral e medial externa do membro. O retorno da plena capacidade de utilização do membro foi observado em 20,00±7,09 dias, e a cicatrização óssea, avaliada por exame radiográfico, ocorreu em 35,12±8,72 dias. Os resultados do experimento demonstraram que redução aberta e aplicação de fixador esquelético externo Tipo II é método efetivo para o tratamento de fraturas de tibiotarso em galinhas da raça Plymouth Rock Branca.

Parameter optimization of AC rectangular wave outputs for aluminum cold wire GTAW

The objective of this work was to optimize the parameter setup for GTAW of aluminum using an AC rectangular wave output and continuous feeding. A series of welds was carried-out in an industrial joint, with variation of the negative and positive current amplitude, the negative and positive duration time, the travel speed and the feeding speed. Another series was carried out to investigate the isolate effect of the negative duration time and travel speed. Bead geometry aspects were assessed, such as reinforcement, penetration, incomplete fusion and joint wall bridging. The results showed that currents at both polarities are remarkably more significant than the respective duration times. It was also shown that there is a straight relationship between welding speed and feeding speed and this relationship must be followed for obtaining sound beads. A very short positive duration time is enough for arc stability achievement and when the negative duration time is longer than 5 ms its effect on geometry appears. The possibility of optimizing the parameter selection, despite the high inter-correlation amongst them, was demonstrate through a computer program. An approach to reduce the number of variables in this process is also presented.

Comparação entre diferentes concentrações e épocas de aplicação de cloreto de mepiquat, cloreto de clorocolina e ethephon em algodoeiro (Gossypium hirsutum L. cv. (AC - 17)

No ano agríco la de 1978/79 instalou-se um ensaio na área experimental da Escola Superior de Agricultura "Luiz de Queiroz", USP, em Piracicaba, SP, tendo por objetivo estudar os efeitos de reguladores vegetais, em diferentes doses e épocas de aplicação, sobre a cultura do algodoeiro (Gossypium hirsutum L. ). Os tratamentos utilizados foram: cloreto de mepiquat (DPC) nas concentrações de 84, 167 e 250ppm, cloreto de clorocolina (CCC) nas dosagens de 250, 380 e 450ppm e ethephon (CEPA) nas concentrações 1670, 3340 e 6880ppm, sendo cada substância aplicada 51, 65 e 143 dias após a germinação, respectivamente. CCC e DPC tornaram mais compacta a arquitetura das plantas de algodoeiro, assim como promoveram reduções nos parâmetros da análise de crescimento. O número de ramos produtivos e de maçãs não foi afetado por esses reguladores. Foram notadas algumas variações nos parâmetros de produtividade, sendo que CCC, DPC e CEPA tenderam a aumentar o peso médio de algodão por planta . Esses produtos não depreciaram os caracteres agronômicos do algodão, nem as características tecnológicas.

Reaching influential early adopters effectively in Finland : Rock Science – new generation board game

Innovations diffuse at different speed among the members of a social system through various communication channels. The group of early adopters can be seen as the most influential reference group for majority of people to base their innovation adoption decisions on. Thus, the early adopters can often accelerate the diffusion of innovations. The purpose of this research is to discover means of diffusion for an innovative product in Finnish market through the influential early adopters in respect to the characteristics of the case product. The purpose of the research can be achieved through the following sub objectives:  Who are the potential early adopters for the case product and why?  How the potential early adopters of the case product should be communicated with?  What would be the expectations, preferences, and experiences of the early adopters of the case product? The case product examined in this research is a new board game called Rock Science which is considered to be incremental innovation bringing board gaming and hard rock music together in a new way. The research was conducted in two different parts using both qualitative and quantitative research methods. This mixed method research began with expert interviews of six music industry experts. The information gathered from the interviews enabled researcher to compose the questionnaire for the quantitative part of the study. Internet survey that was sent out resulted with a sample of 97 responses from the targeted population. The key findings of the study suggest that (1) the potential early adopters for the case product are more likely to be young adults from the capital city area with great interest in rock music, (2) the early adopters can be reached effectively through credible online sources of information, and (3) the respondents overall product feedback is highly positive, except in the case of quality-price ratio of the product. This research indicates that more effective diffusion of Rock Science board game in Finland can be reached through (1) strategic alliances with music industry and media partnerships, (2) pricing adjustments, (3) use of supporting game formats, and (4) innovative use of various social media channels.

Rock outcrop vegetation in Brazil: a brief overview

This paper overviews the special issue of the Brazilian Journal of Botany dedicated to "Rock outcrop vegetation in Brazil". The main topics covered by this issue are phytogeography and vegetation ecology, plant life on shallow soils, plant reproduction and auto-ecology, morpho-physiology and plant adaptation, and finally conservation and global change. This collection of studies, in addition to other recent publications on Brazilian rocky outcrop vegetation, show that measurements of most of the relevant ecological and evolutionary parameters are under way and that scientific attention is now given to most Brazilian regions. However, there are still several gaps to be bridged: 1) inselbergs and high mountains in the Amazon and the Brazilian northeast, in particular, are still largely unknown to science; 2) long-term studies are almost totally unavailable, which hinders global change monitoring and assessment; 3) national and international networking are urgently needed to speed up scientific production about such habitats.

Soils associated with rock outcrops in the Brazilian mountain ranges Mantiqueira and Espinhaço

Espinhaço and Mantiqueira are two mountain ranges of great importance in Brazil. In the uppermost parts of these areas, unique ecosystems occur, generally associated with rock outcrops, they are collectively called High Altitude Rocky Complexes. These environments show distinct soil and biota characteristics in relation to the surrounding biome. The soils are generally shallow, coarse textured, with high Al3+ and varying amounts of organic matter. Entisols, Inceptsols and Histosols are dominant, directly associated with the rock outcrops, and forming a complex mosaic of soils. Some of these soils are endemic, based on peculiar conditions of parent materials, topography and vegetation, and this pedodiversity is important for detecting unique and endangered soils. In these soils, organic matter is highly humified, with a great amount of soluble forms and conspicuous presence of charcoal. Spodic horizons and dark water rivers are typically associated with quartzite and quartzite outcrops, formed by illuviation of organic compounds, being less common in granitic rocks. The very low nutrient content of these soils and other environmental limitations required the development of specific physiological and morphological plant adaptations. Most high altitude environments are unstable under current climatic conditions, and anthropic interventions may be accelerating this process. Detailed soil surveys are necessary for a better understanding of the role of these soils in ecological processes and for the development of adequate conservation policies.

Rock outcrop habitats in the Venezuelan Guayana lowlands: their main vegetation types and floristic components

The Guayana Shield, located in north-eastern South America, consists of a highly complex and composite mosaic of landscape elements. Amongst these, inselbergs are very conspicuous, because of their peculiar shape and their unusual associated vegetation. Geologically, these rock outcrops are part of the underlying ancient igneous-metamorphic basement and occur mainly in the lowlands of the periphery of the shield. As azonal habitats, inselbergs harbour a highly specialized flora. The characteristic vegetation is composed of lithophytic and savanna-like plant communities, as well as low dry forests. As a whole, the vegetation of an inselberg may be interpreted as a mosaic of marginal habitats. Therefore a large number of taxa find suitable niches in a quite condensed space. Gradients of soil depth and water availability are the main factors determining the floristic composition. A preliminary floristic inventory of the Venezuelan inselberg flora comprises 614 vascular plant species. 24% of them are endemic to the Guayana region, 15% are endemic to inselbergs of the Guayana region. The distribution patterns of these latter, eco-endemic species allows to distinguish a northern and a southern inselberg district. The two districts overlap in the Átures area, in the surroundings of Puerto Ayacucho, where a true centre of endemism is located. The distinction into two districts is emphasised by different phytogeographic relations. The southern inselberg district shows connections to the "tepui" flora, whereas the northern district reveals phytogeographic relations to the Caribbean region as well as to the Brazilian Shield. Possible explanations for the floristic interchange across the equator are discussed.

Species composition and biogeographic relations of the rock outcrop flora on the high plateau of Itatiaia, SE-Brazil

We studied the flora of vegetation islands on rock outcrops on the Itatiaia Plateau (22°21'S and 44°40'W), at 2,400 m.a.s.l. A total of 114 vascular plant species, which correspond to ca. 20%-25% of the currently inventoried flora of the plateau, were sampled in 197 small vegetation islands (total area of 0.034 ha). Xerophytes and hydrophytes were often found side by side due to environmental heterogeneity at a small scale, explaining in part the high species diversity. Rock outcrops may support floras quite distinct from those in neighbouring habitats, due to the action of strong environmental filters, but in Itatiaia the geographic distribution patterns among rupicolous plants appear to mimic those described for the whole flora around it, with 15.1% of narrow endemic species and six strictly rupicolous plants. Underlining the "temperate" nature of the high elevation climate in Itatiaia, the sampled flora was dominated by species of the families Asteraceae and Poaceae, and the number of CAM (crassulacean acid metabolism) species was very low. A few endemic species of tropical origin - Pleurostima gounelleana (Beauv.) Men. (Velloziaceae) and Fernseea itatiaiae (Wawra) Baker (Bromeliaceae) - play a crucial role in this vegetation, as pioneer mat-formers facilitating later establishment of numerous other species. Hemicryptophytes prevail in the sampled flora, while therophytes are exceptionally rare and mainly consist of opportunistic species associated with disturbances. Numerous microhabitats and strong environmental gradients in these high elevation rock outcrops afford opportunities for establishment of a highly diversified flora. These island-like environments may represent an important refuge for grassland species from fire and other disturbances in the surrounding grasslands.

Structural analysis of the vegetation on a highland granitic rock outcrop in Southeast Brazil

Granitic rock outcrops of the Brazilian southeast are either coastal or inland. The latter can often have high altitudes, such as in the summits of "Serra do Mar" and "Serra da Mantiqueira", where they are known as "Campos de Altitude". The landscape on these high altitude plateaux is often a mosaic of shrubs and treelets within a bunchgrass matrix, with sparse pteridophytes and other herbs, interspersed with variable extensions of rock outcrops. Despite the pervasiveness of rock outcrops in the Brazilian landscape, studies on the structural analysis of the vegetation on such formations are scarce. This study aimed to analyze the structure of the vegetation on a highland granitic rock outcrop in "Parque Estadual da Serra do Brigadeiro", state of Minas Gerais, Southeast Brazil (42°20' - 42°40' S and 20°20' - 21°00' W, 1,722 m of elevation ). Quantitative parameters of absolute and relative frequency and dominance (cover) were estimated. The group analysis used the Jaccard similarity index. Trilepis lhotzkiana, Panicum sp. 1, and Vellozia variegata presented the highest relative frequencies, relative dominances and importance values. These three species, along with Dyckia bracteata, Rhynchospora emaciate, and Tibouchina cf. manicata, represented 98.3% of the relative dominance. The remaining 1.7% referred to 22 remaining species. The distinction among quadrats within formed groups by cluster analysis was due to the great number of low frequency species.

Water relations of tree species growing on a rock outcrop in the "Parque Estadual de Itapuã", RS

Water relations of the tree species Myrsine umbellata Mart. ex A. DC., Dodonaea viscosa Jacq. and Erythroxylum argentinum O. E. Schulz, growing on a rock outcrop in the "Parque Estadual de Itapuã" (RS), were studied. Environmental (precipitation, temperature, soil water) and plant (water potential, vapor pressure deficit, stomatal conductance, transpiration, leaf specific hydraulic conductance, osmotic potential and cell wall elasticity) parameters were collected in five periods and pooled into two sets of data: wet and dry periods. Myrsine umbellata showed great stability of the plant parameters, including the maintenance of high pre-dawn (psiwpd) and mid-day (psiwmd) water potentials in the dry period (-0.48 and -1.12 MPa, respectively), suggesting the presence of a deep root system. Dodonaea viscosa and E. argentinum reached lower psiwpd (-1.41 and -1.97 MPa, respectively) and a greater degree of stomatal closure in the dry period, suggesting a shallower root system. Differential exposure to soil drought was also corroborated by differential drought effects on the whole-plant leaf specific hydraulic conductance (Gt). Correlation analysis pointed to weak correlations between psiwpd and g s. Erythroxylum argentinum was the only species to show osmotic adjustment in response to drought. It is suggested that M. umbellata has low tolerance to water deficits, adopting an avoidance behavior. The much lower values of psiw reached by D. viscosa and E. argentinum suggest a greater tolerance to drought by these species.