No description available.

The Ditrău Alkaline Massif (Romania) is located in the Eastern Carpathians, as an intrusion in the Bukovina nappe system of the Mesozoic crystalline zone. Nepheline syenites are the most abundant rocks occurring in the central and eastern part of the Massif, and represent the youngest intrusion of the complex. Petrographic observations and fluid inclusion studies were performed on nepheline syenites in order to examine the evolution and the effect of the magmatic fluids on the alteration of nepheline to secondary minerals as sodalite, cancrinite and analcime. Fluid inclusion studies in nepheline, aegirine, albite and cancrinite provide evidence for the role of highly saline fluids in incongruent transformation reactions by which sodalite, cancrinite and analcime crystallize mostly on the expense of nepheline. The fluids, in most cases, can be modeled by the H2O-NaCl system with various NaCl contents; however inclusions with more complex fluid (containing also K, Ca, CO3, etc. besides H2O and NaCl) composition are abundant. Raman spectroscopic studies of daughter minerals in inclusions demonstrate the presence of alkali-carbonatic fluids in some of the earliest inclusions of nepheline, aegirine and albite. The alteration process is supported by the presence of H2O-NaCl fluid inclusions in cancrinite, showing lower salinity compared to those in nepheline. During the crystallization period of the nepheline syenites the rock was in equilibrium with a high salinity, carbonate rich solution that evolved to decreased salinity with time. The following observations support this: • paragenesis of mineral phases and their fluid inclusions: the early phases have high salinity inclusions and the late phases have low-salinity inclusions • the partitioning of chlorine depends on the pressure of the system: at about 2.0 kbars, the fluids coexisting with the melt have a high initial salinity and the salinity decreases with time; inclusions in nepheline show the lowest trapping pressure at ~2.5 kbars, hence the system has a high initial salinity and decreases with time • aH2O increases with time, resulting in the formation of H2O-bearing phases in a late stage of the crystallization of nepheline syenites. / Master of Science

No description available.

Thesis (M. Sc.)(Geology)--University of Pretoria, 2006. / Includes bibliographical references. Available on the Internet via the World Wide Web.

<p> Nepheline syenite samples were collected from the Bancroft and Blue Mountain areas, Ontario, Canada, and were analysed for K, Rb, and Tl contents by atomic absorption spectrophotometry. The results for these elements and the corresponding K/Rb, K/Tl and Rb/Tl ratios were compared with those of nepheline syenites in various localities, and were found to be similar.</p> <p> The Tl, Rb, K contents and the K/Rb, K/Tl and Rb/Tl ratios in this study were determined to be 825 ppb, 110 ppm, 3.28%, 298, 4.11x10^4 and 135 respectively for the Bancroft nepheline syenite gneisses, and 574ppb, 93ppm, 3.28%, 353, 5.71x10^4 and 162 respectively for the Blue Mountain nepheline syenites. From these data, the nepheline syenite rocks in this study were probably originated as continental plutonics.</p> / Thesis / Bachelor of Science (BSc)

O controle das características da escória de refino primário pode ser realizado pela adição de fluxantes, sendo comumente utilizado a Fluorita (CaF2), isto porque a Fluorita aumenta a solubilidade de CaO e, por conseguinte, aumenta a capacidade de desfosforação de escória. Apesar disso, alguns estudos advertem sobre o risco de liberação de gás tetra fluoreto de silício, que tem caráter nocivo para o meio ambiente. Outro problema relatado é o aumento do desgaste do revestimento refratário impactando nos custos de produção. Neste trabalho de mestrado o uso de Sodalita Nefelínica como fluxante foi comparado com a Fluorita em relação ao desgaste de refratários a base de MgO-C e à fluidez. Os ensaios consistiram em dopar escória de conversor LD com diferentes quantidades de Fluorita e Sodalita (1, 2, 3, 4 % em massa). Os resultados demonstraram que a Fluorita fornece uma escória com menor ponto de fusão e mais fluida, porém ela causa maior desgaste no revestimento refratário, mais que o dobro do desgaste causado pela Sodalita. Acredita-se que isso tenha ocorrido devido a Fluorita ser capaz de aumentar a dissolução tanto do CaO presente na escória quanto do MgO presente no refratário. Este processo é intensificado pela baixa viscosidade apresentada com este fluxante. / The control of the slag characteristics from primary refining can be accomplished by adding fluxes, being commonly used Fluorite (CaF2). This happens because the fluorite increases the solubility of CaO and thus increases the ability of the slag dephosphorization. Nevertheless, some studies warn about the risk of releasing silicon tetra-fluoride gas which has harmful character to the environment. Another problem reported is the increased wear of the refractory lining impacting on production costs. In this master dissertation the use of Sodalite Nepheline as flux was compared with Fluorite concerning MgO-C based refractories wear and fluidity. The tests consisted of doping LD converter slag with different amounts of Fluorite and Sodalite (1, 2, 3, 4 % mass). The results showed that the Fluorite provides a slag with a lower melting point and becomes more fluid, but it causes greater wear on the refractory lining, more than double the wear caused by Sodalite. It is believed that this has occurred due Fluorite be able to enhance the dissolution of the CaO in slag as well as MgO present in the refractory. This process is intensified by the low slag viscosity presented with this flux.

O controle das características da escória de refino primário pode ser realizado pela adição de fluxantes, sendo comumente utilizado a Fluorita (CaF2), isto porque a Fluorita aumenta a solubilidade de CaO e, por conseguinte, aumenta a capacidade de desfosforação de escória. Apesar disso, alguns estudos advertem sobre o risco de liberação de gás tetra fluoreto de silício, que tem caráter nocivo para o meio ambiente. Outro problema relatado é o aumento do desgaste do revestimento refratário impactando nos custos de produção. Neste trabalho de mestrado o uso de Sodalita Nefelínica como fluxante foi comparado com a Fluorita em relação ao desgaste de refratários a base de MgO-C e à fluidez. Os ensaios consistiram em dopar escória de conversor LD com diferentes quantidades de Fluorita e Sodalita (1, 2, 3, 4 % em massa). Os resultados demonstraram que a Fluorita fornece uma escória com menor ponto de fusão e mais fluida, porém ela causa maior desgaste no revestimento refratário, mais que o dobro do desgaste causado pela Sodalita. Acredita-se que isso tenha ocorrido devido a Fluorita ser capaz de aumentar a dissolução tanto do CaO presente na escória quanto do MgO presente no refratário. Este processo é intensificado pela baixa viscosidade apresentada com este fluxante. / The control of the slag characteristics from primary refining can be accomplished by adding fluxes, being commonly used Fluorite (CaF2). This happens because the fluorite increases the solubility of CaO and thus increases the ability of the slag dephosphorization. Nevertheless, some studies warn about the risk of releasing silicon tetra-fluoride gas which has harmful character to the environment. Another problem reported is the increased wear of the refractory lining impacting on production costs. In this master dissertation the use of Sodalite Nepheline as flux was compared with Fluorite concerning MgO-C based refractories wear and fluidity. The tests consisted of doping LD converter slag with different amounts of Fluorite and Sodalite (1, 2, 3, 4 % mass). The results showed that the Fluorite provides a slag with a lower melting point and becomes more fluid, but it causes greater wear on the refractory lining, more than double the wear caused by Sodalite. It is believed that this has occurred due Fluorite be able to enhance the dissolution of the CaO in slag as well as MgO present in the refractory. This process is intensified by the low slag viscosity presented with this flux.

A petrographic study has been made of the contact relations between metagabbro and nepheline gneiss underlain by marble, in Monmouth township, Haliburton County, Ontario. A bad of hornblende nepheline-garnet gneiss about 80 feetwide trending north-south is underlain at a shear contact by marble. Round inclusion up to 18 inches across of red pyroxene with some spinel and rimmed by olivine occur in the marble a few feet below the contact. For a few inches above the contact the nepheline gneiss sometimes is biotite-bearing. To the east the nepheline gneiss grades into a band of hybrid nepheline metagabbro (containing pink augite) about 50 feet wide. This in turn is followed by a zone of garnetiferous clinozoisite metagabbro about 220 feet wide. Clinozoisite persists in the metagabbro for 100 feet beyond this zone and is followed by hornblende-(pyroxene)-plagioclase metagabbro. Pyroxene-garnet-(nepheline) skarn is interlayered with nepheline gneiss at one outcrop ear the fault contact with marble. It appears that gabbroic magma has intruded limestone and developed a skarn at the contact. Assimilation of lime by the magma has developed pink augite (titanaugite ?) , clinozoisite and grossularite in the gabbro. Subsequent injection of a highly fluid nepheline magma, or of solutions containing soda, alumina and iron and not saturated with silica, formed nepheline-bearing rock between marble and gabbro. Soda metasomatism produced a hybrid nepheline gabbro adjacent to the nepheline-bearirg rock. Regional metamorphism later imparted a foliation to the marble and nepheline rock, and produced a metamorphic texture the gabbro. Faulting of a unknown age brought nepheline gneiss and marble into sharp contact and probably trapped the skarn as horses only one of which is now exposed. / Thesis / Doctor of Philosophy (PhD)

Mamelodi Quarries, which currently mine the Franspoort nepheline syenite, produces aggregate and crusher sand for the local building industry. The mine is located northeast of Pretoria, South Africa on the road to Cullinan. The aim of this study is to investigate the use of the Franspoort nepheline syenite as an alumina and alkali resource for the glass and ceramics industry at Mamelodi Quarries, and to evaluate the production of a concentrate of zircon and rare earth elements as economic by-products. International standards require a nepheline product with a ferric oxide content of less than 0.35 weight percent. The Franspoort nepheline syenite contains 3.37 weight percent of ferric oxide. The iron-containing minerals present are aegirine, aegirine-augite, magnetite, ilmenite and pyrite. The removal of iron-bearing minerals was attempted by high-intensity wet magnetic separation, low-intensity dry magnetic separation, spiral gravity separation, and heavy liquid separation to produce a saleable nepheline product. This product is the cleaned final concentrate, of the different separation tests, which contains the lowest iron concentration for application in the glass and ceramic industry. The mineral assemblage was determined with a petrographic study as well as X-ray diffraction and electron microprobe analyses. Material from the different separation tests was analysed with X-ray fluorescence to obtain the chemical composition and to evaluate the final iron content of the nepheline product. The dry magnetic separation method produced the best results. The nepheline product has a ferric oxide content of 0.68 weight percent compared to the starting concentration of 3.37 weight percent. The ferric oxide concentration is, however, above the accepted levels for the glass and ceramics industry. The ferric oxide content is attributed to small iron-rich mineral inclusions, which are locked in feldspar and nepheline. The final nepheline product is not suitable for the use in the glass and ceramic industry. Zircon was concentrated the best by the use of heavy liquid separation. Zircon is in most cases locked in the minerals albite, microcline, and nepheline. The rare earth elements are mostly associated with zircon and fluorite and therefore it will not be viable to produce it as a by-product. Copyright / Dissertation (MSc)--University of Pretoria, 2010. / Geology / unrestricted

<p>Four different kinds of filter-materials with reactive surfaces have been studied concerning their capacity to absorb heavy metals in leachate from a municipal waste deposit. The heavy metals studied were: lead, cadmium, copper, mercury, chromium, nickel and zinc. The leachate contains high levels of dissolved organic carbon (DOC) and has a high pH-value along with a high buffer capacity. These characteristics of the leachate make it difficult to remove pollutants and require efficient filters. The filters that were examined in the report are blast-furnace slag with CaO, sand covered with iron oxides, olivine and nepheline. The experiment was carried out in two sets, starting with batch experiments followed by a column study. The objective of the batch experiments was to find out how variations in pH affected the sorption capacity of the materials. The interval used during the test was from pH 5 to pH 10. The computer program VisualMinteq was used to evaluate the dominating sorption processes when the materials interacted with the solutions. Two different kinds of solutions were used in the batch experiment. One of them was the leachate, to which known concentrations of heavy metals were added (about 1 μM) and the other consisted of sodium nitrate, a solution without organic compounds, which was used as a reference. The sodium nitrate solution was also spiked with the same concentration of heavy metals as the leachate.</p><p>The results from the batch experiment showed that the sorption of heavy metals was lowered if the DOC level was high. No relation between pH and sorption ability could be found for the leachate, but for some metals in the sodium solution a higher pH improved the removal of heavy metals. The two materials that showed best results in the batch experiment were the blast-furnace slag and the sand with iron oxides. These materials were used in the column study. The olivine material was somewhat better than the nepheline in the batch experiment.</p><p>Four columns were used in the column study, two for each material. Leachate with heavy metals was pumped into the columns with a specific flow rate; at first a low flow rate was used and when half the experiment time had passed the flow rate was increased. The flow rates used were 0.12 m/24 h and 0.62 m/24 h. The outcome of the column experiment showed that the slag had the highest ability to adsorb metals. The metal sorption was over 60 percent for lead, cadmium and zinc, where the highest sorption was obtained for lead. No affects were noticed when the flow rate was increased.</p> / <p>I detta examensarbete har fyra olika reaktiva filtermaterials kapaciteter att ur deponilakvatten avskilja tungmetallerna bly, kadmium, koppar, kvicksilver, krom, nickel och zink testats. Deponilakvatten är ett avloppsvatten med höga halter organiskt material (DOC), högt pH och en hög buffertkapacitet. Dess sammansättning ställer stora krav på ett filter och närvaron av ligander påverkar sorptionprocesserna. Filtren som ingått i studien är kalciumoxiddopad masugnsslagg, järnoxidtäckt sand, olivin och nefelin.</p><p>Försöken utfördes i två delar, med inledande skakförsök och därefter kolonnförsök. I båda försöken användes lakvatten med en extra tillsats av tungmetaller. I skakförsöken användes även natriumnitrat; ett referensvatten utan organiska ligander, även det spikat med tungmetaller. I skakförsöken studerades avskiljningens pH-beroende för de olika filtren, med ett pH-intervall på ca 5 – 10. Därefter modellerades resultaten i jämviktsprogrammet VisualMinteq för att fastställa vilka processer som styr avskiljningen. Skakförsöken och kolonnförsöken utfördes båda i klimatrum vid 8 ºC, för att efterlikna markens naturliga temperatur.</p><p>Resultaten från skakförsöken visade att masugnsslagg och järnoxidsand gav bäst avskiljning för de flesta tungmetaller. Olivin och nefelin var sämre metallsorbenter, där olivin uppvisade något bättre resultat än nefelin. Inget tydligt pH-beroende för lakvattnet kunde utläsas, men för natriumnitratlösningen gav en pH-höjning en ökad sorption för vissa metaller. Den kemiska jämviktsmodelleringen visade att den dominerande processen i filtermaterialen var sorption på filterytorna. De två filtermaterialen som visade bäst resultat i skakförsöken (slagg och järnoxid) studerades vidare i kolonnförsök, där ett bestämt lakvattenflöde pumpades genom kolonner packade med materialen. Två olika flödeshastigheter testades (0,12 m/dygn och 0,62 m/dygn) och sorptionen av metaller analyserades. Slaggen uppvisade högst avskiljningskapacitet av de studerade filtren. De metaller som sorberades bäst var bly, kadmium och zink (över 60 % avskiljning), där den högsta sorptionen erhölls för bly. Gemensamt för både skak- och kolonnförsöken var att sorptionen försvårades då halten organiskt material (DOC) ökade, vilket beror på att DOC konkurrerar med de reaktiva ytorna på filtren om att binda den fria metalljonen. Ingen minskande avskiljningseffekt av en flödesökning kunde utläsas.</p>