<p> Levitation melting was used to measure the equilibrium between H2-H2o or CO-C02 gas mixtures and pure Fe or Fe-Cr alloys over the temperature range 1550 - 1750°C. The effects of thermal diffusion on the two types of gases were investigated. First and second order interaction parameters were employed to describe the interaction between oxygen and chromium {up to 25 wt. pct. of Cr.). </p> / Thesis / Master of Science (MSc)

The European commission has in the Energy Performance of Buildings Directive from 2010 decided that its member states were required to ensure that all new buildings by the end of 2020 were nearly zero-energy buildings. These buildings require small amounts of energy compared to its performance in example by keeping a pleasant indoor climate. To achieve these goals there is an option for integrating phase changing material into building material.   The purpose of this project was to determine which kind of PCM is suitable for use in building materials to increase its fire resitance, taking inspiration from the report Fasomvandlingsmaterial: Risker och möjligheter written by Michael Försth, Alexandra Byström and Jonathan Wolf. In particular, the aim was to observe if the application of PCM, in pure powder form, into pure concrete could increase the time until it reaches it critical temperature of 500 °C. The choice of PCM to be used was decided by a literature review and initial thermal tests, and in this case, Magnesium Carbonate Hydroxide Pentahydrate, MCHP, was used as a substitute for the cement, in this project.    The project has been carried out through a literature review and laboratory experiments. The laboratory experiments were performed in different stages. First, the thermal properties of the PCM were decided by using a DSC (differential scanning calorimeter) and a TGA (Thermogravimetric analysis). Three kinds of PCMs (Magnesium hydroxide, Aluminium hydroxide and MCHP) were tested from the results of the literature review. The DSC gave a variation in results between the three tested PCMs. MCHP showed two melting phases which produced different kind of fire-retardant products and theoretically would give two instances of stopping the heating of the concrete. With that MCHP was then chosen as the most appropriate one to be incorporated into concrete. From there, pure concrete samples and with PCM mixed in, with different weight percentage varying between 2-10 weight percent (wt.%) of the cements weight, with a thermocouple embedded in the bottom were manufactured. Thereafter, a cone calorimeter was used with the constant heat flux of 50 kW·m-2 as a source of heat radiation.   The results shows that the application of the PCM in the concrete by replacing the cement does not give any noticeable increase in its fire resistance by increasing the time until it reaches 500 °C. Neither did it show any signs of the heating curve to flatten out, which in theory would have occurred during melting of the PCM. This could depend on the way the heat transfers down through the concrete and melts the PCM along the way towards the bottom and the thermocouple measuring the temperature. Making the thermocouple only register the heating of the concrete in close proximity to it. Therefore only a small amount of PCM melts and the required energy is not enough to halt the heating. Theoretical calculations performed showed that the melting of the PCM in the case with 5 and 10 wt.% gave an improvement by increasing the time until critical temperature is reached with 4 % and 7.3 %, compared to a pure concrete sample. The melting of the PCM is responsible for 1 % respectively 2 % of that time increased compared to the pure concrete sample. The rest of the increase in time comes from the PCMs thermal properties which is higher than the cement. The literature study shows that there exist many suitable PCM for increasing a building material’s fire resistance, some of which are already used as fire retardants. It also shows that PCM can affect a material’s fire resistance in more ways than just the heat storage (latent heat) in the melting phase.    The conclusion of this report is that substituting concrete with MCHP in powder form is not suitable and does not affect the concretes fire resistance. But the usage of PCM in concrete should not be dismissed. There exist different ways to implement the PCM into the concrete which could give a desirable result.

The Enåsen gold deposit is located in Gävleborg county in central Sweden. Mining operations at Enåsen took place from 1984 to 1991 with Au as the main target for exploitation. The deposit has been interpreted as a metamorphosed Palaeoproterozoic analogue to near-recent epithermal Au mineralisations of a high sulphidation type. Its present mineralogy, textural-structural features, and morphology have been suggested to be the result of a combination of later deformation and regional Svecokarelian metamorphism at upper amphibolite to granulite facies conditions of the original epithermal deposit and it’s hydrothermally altered host rock. The main ore body now consists of a mineralised sillimanite quartzite gneiss. The aim of the project was to characterise the ore mineralogy, petrography and its paragenesis, evaluate the potential of Enåsen in terms of critical metals, and to test a hypothesis of partial ore melting.Among the most frequent ore minerals in the deposit are pyrite, chalcopyrite, pyrrhotite, bornite and tetrahedrite-tennantite, with variable but less abundant sulphides including covellite, digenite, mawsonite, stannite, arsenopyrite, cobaltite, galena, marcasite, sphalerite and pentlandite. Additionally, native gold, Se-bearing tellurobismuthite, hessite, tsumoite, pilsenite, rickardite, vulcanite, altaite, molybdenite, frohbergite, montbrayite, tellurantimony, löllingite and tellurbismuthantimony. While not an ore mineral here, rutile occurs abundantly. The ore mineral assemblages have seemingly at least partially melted. This is evidenced by failed quenching textures in the form of abundant multi-scale symplectites, potential sharp dihedral angles, localised concentrations of low melting point chalcophile elements (LMCE) + Au and Ag and arrays of multiphase sulphide/sulphosalt ± gold inclusions, as well as available mineral stability data considering that the ore assemblages have been subjected to upper amphibolite/granulite facies conditions followed by ductile and brittle deformation stages. Some ore mineral relationships have been described. Further studies would be required for a full paragenesis. The potential of Enåsen type deposits in terms of critical or near critical metals and semi-metals is likely to be as biproduct extraction in a mining operation aimed at gold. The most relevant element is likely to be bismuth, followed by tellurium and antimony.

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