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Dissolution kinetics of nickel from lateritic ore in nitric acid solution was investigated. Experimental parameters used were stirring speed (100-600 r/min), temperature (40-96 °C), nitric acid concentration (0.1-2 mol/L) and particle size (

URL:http://sujest.selcuk.edu.tr/sumbtd/article/view/457 DOI: 10.15317/Scitech.2017.98, The natural rocks used today as well as in the history for a variety of purposes were a subject of different alteration, weathering and deterioration conditions. These conditions are strictly controlled by environment and nature of rock varieties (marble and stone). This study is a first approach to understand the relation between some geological features and behavior against salt (Na2SO4) decay of Moroccan marbles and stones. For this purpose, widely used four dolomitic limestones, two crystalline limestones, one limestone and one basalt sample (total 8) were chosen from Morocco. Extra attention paid to choose locations being a representative of all Moroccan country. The carbonate samples (limestone and dolomite) consist of mainly dolomite and calcite with micritic and sparitic cement. The sole, non-carbonaceous sample is basalt of Khenifra containing mainly plagioclase and pyroxene. In general, both bulk-dry and powder density values of the studied rock samples are homogeneous. The limestone of Bir Jdid has the highest (10.81 %) effective porosity and dry weight loss value (4.61 %). The loss on ignition value of the Khenifra basalt has the lowest value with 1.26 %. The loss on ignition values are also relatively uniform. The obtained data indicate that outdoor uses (especially in coastal areas) of limestones of Bir Jdid and dolomitic limestones of Taza are more risky than the others., Hem geçmiş dönemlerde hem de günümüzde çok çeşitli amaçlar için kullanılan doğal taşlar farklı ayrışma, dağılma ve bozunmaya uğramaktadırlar. Bu şartlar çevre ve kayacın türüne (mermer ve taş) sıkı sıkıya bağlıdır. Bu çalışma Fas mermerleri ve taşlarını tuza (Na2SO4) karşı dayanımlarını ve bazı jeolojik özelliklerini anlamak için yapılan ilk çalışmadır. Bunun için Fas’tan getirilen çok kullanılan 4 dolomit, 2 kristalize kireçtaşı, 1 kireçtaşı ve bir bazalt (toplam 8 adet) örneği seçilmiştir. Örnekler mümkün mertebe Fas’ın değişik yerlerinden seçilmiştir. Karbonat kayaçları (kireçtaşı ve dolomit) temel olarak dolomit ve kalsit minerallerinden müteşekkil olup çimento mikrit ve sparittir. Karbonatsız tek kayaç olan Khenifra bazaltı esasen plajiyoklas ve piroksen içerir. Genel olarak örneklerin kuru ve öğütülmüş ağırlıkları birbirlerine benzer. Bir Jdid kireçtaşları en yüksek etkili porozite (% 10.81) ve kuru ağırlık kaybına (%4.61) sahiptir. En düşük ateş zayiatı Khenifra bazaltlarındadır (%1.26). Ateş zayiatları genel olarak homojendir. Eldeki veriler Bir Jdid kireçtaşları ve Taza dolomitik kireçtaşlarının dışarda (özellikle sahil bölgelerinde) kullanımlarının diğerlerine göre daha riskli olduğuna işaret etmektedir.

Turkey has important chromite, magnesite and olivine deposits within peridotite host rocks. The peridotites (harzburgite, verlite, lherzolite and dunite) are mostly serpentinised as a result of metasomatic reaction of olivine and pyroxene minerals with percolating water. The serpentinites are generally an important part of ophiolitic complexes which displays a discontinuous belts all over the country. The chromite deposits are often related to cumulates and tectonites (as Alpine and/or podiform type deposits) and despite their small reserves, their grade can reach up to 58 %. In most deposits, a little enrichment efforts, the grade of chromite can easily be reached from 25 % to 40-45 %.The magnesite deposits of West Anatolia is especially concentrated in three provinces. These provinces are Konya, Kutahya and Eskisehir. The magnesites are of cryptocrystalline type and, like chromite deposits, their reserve are small but have high grade with low FeO-CaO and high MgO ratio. Once again, these deposits are fo...

Approximately 8% of Turkey is covered by ultramafic rocks which host economically important deposits of magnesite, chromite and olivine. Magnesite deposits are of three types: (1) Massive or crystalline, (2) Cryptocrystalline and (3) Sedimentary. Cryptocrystalline and sedimentary type magnesite deposits are widespread all over Turkey although the massive type deposits are seemingly absent. In this study, we examined the sedimentary magnesite deposits of Hirsizdere, located in the province of Denizli, SW Turkey. The deposits formed as five beds within an ultramafic environment. The thickness of the magnesite beds can reach up to 4 meters and may be traced up to 3 km from west to east. The deposit comprises half a million tons of magnesite with some associated dolomite.

Vein stockworks and lacustrine developments of cryptocrystalline magnesium carbonates of Neogene and Quaternary age occur within the partially serpentinized, discontinuous ultramafic belts of southwestern Turkey. They are comparable to the Neogene cryptocrystalline magnesite bodies elsewhere in the Alpine orogen to the northwest and southeast. Our previous work (Fallick et al., 1991) suggested that cool (less than or equal to 100 degrees C) modified meteoric water was the mineralizer, that ultramafic rock was the source of the magnesium, but that there were three separate sources of the (bi)carbonate. These sources were distinguishable by their stable isotope composition as follows: (1) low-temperature carbonate with delta(18)O((SMOW)) values of similar to 36 per mil and delta(13)C((PDB)) values of similar to 4 per mil, derived from atmospheric CO2; (2) moderate-temperature carbonate with delta(18)O((SMOW)) values of +28 per mil and delta(13)C((PDB)) values of -15 per mil, derived by decarboxylation of organic-rich sediments; and (3) higher temperature carbonate with delta(18)O((SMOW)) values of similar to 19 per mil and delta(13)C((PDB)) values of similar to 3 per mil, assumed to have been generated by thermal contact metamorphism of Paleozoic marine limestone at depth. In general these magnesite deposits were found to fall into two groups, comprising carbonate generated on two mixing lines. The first group spanned the putative mixing line from the "atmospheric" source (1) to "organically derived" source of CO2 (2). The second group extended between atmospheric source (1) and the "thermal" source (3), although there were concentrations either around the atmospheric end, or precisely at the contact metamorphic end of the line. In the present study we found that large stockwork deposits at Helvacibaba and Koyakci Tepe have delta(13)C((PDB)) and delta(18)O((SMOW)) values averaging similar to-12 and similar to+27 per mil, respectively, indicating a derivation mainly by oxidation of organic-rich metasediments perhaps underthrust at depth (end-member 2), with some involvement of atmospheric carbon dioxide as bicarbonate in the circulating, hot, and modified meteoric water (end- member 1). Calcite veinlets in a meta-argillite of the Cambro- Ordovician Seydisehir Formation, most likely to have been underthrust beneath the stockworks, yielded delta(13)C((PDB)) values of -20 per mil, consistent with, though not proving, oxidized organic carbon being one of the sources of carbonate. The delta(18)O((SMOW)) values of these same veinlet carbonates are also rather low (22 parts per thousand), indicating precipitation from heated ground water, though their age is unknown. The major stratiform magnesite deposit at Hirsizdere in the center of the Menderes graben has delta(13)C((PDB)) and delta(18)O((SMOW)), values averaging similar to 3 and similar to 25 per mil, respectively and thus appears to be an example of the hydrothermal-sedimentary (i.e., exhalative) type (Ilich, 1968). In contrast, the hydromagnesite stromatolites presently growing in Salda Golu (Lake Salda) are apparently developing at cool ground-water seepages. The gross morphology of the Salda Golu stromatolites and the hydromagnesite sediments derived therefrom is reminiscent of that revealed in the Bela Stena magnesite pit in Serbia. These lacustrine deposits have mean delta(13)C((PDB)) values of similar to 4 and similar to 2 per mil and mean delta(18)O((SMOW)) values of similar to 36 and similar to 33 per mil, respectively, i.e., they both plot broadly over the atmospheric CO2-meteoric water field (end- member 1), consistent with microbially mediated precipitation at cool ground-water seepages in enclosed evaporating lakes.

The 9White Rock9, constituting a portion of what may be a lacustrine sedimentary sequence near the margin of a crater c. 90 km across in Sabaea Terra, Mars, measures 18 × 15 km × 180–540 m high. It is re-interpreted as a lens of magnesium carbonate precipitated where ground waters seeped into an ancient evaporating crater lake. Were life to have emerged on Mars, as seems feasible, then the 9White Rock9 might be expected to comprise a complex of stromatolitic mounds. Salda Golu (Lake) in Turkey, is taken as an analogue. This enclosed lake is nearly surrounded and underlain by partially serpentinized harzburgite. Hydromagnesite stromatolites (microbialites) up to 7 m high coalesce to form a group of small islands 200 m across. The microbialites are seen to be growing near the mouth of the usually dry Salda River in the southwestern sector. Smaller developments of hydromagnesite encircle the lake and image processing of satellite data reveals a second extensive zone beneath the lake surface over a delta in the southeast. Individual columns a few centimetres high constitute bulbous mounds which are about 2 m in diameter. These columns terminate in domes a centimetre or so across. The domes are often annulated and are covered with a green biofilm a few millimetres thick comprised of cyanobactrial filaments. The columns consist of alternating fine and coarse hydromagnesite layers differentiated on a millimetric scale. The coarser layers near the surface still contain traces of the biofilm. Fossil microbialites were also discovered in the friable hydromagnesite cliffs shoreward of the main developments, though the structures of the individual microbes have not survived. Instead the vestiges of microbialites are easily recognized and delineated by their coarse grain size and high porosity. Annular structures on their upper surfaces can be seen in places. The intervening and overlying material, also comprised of hydromagnesite, is a semi-lithified mud. Bulbous megascopic structures, separated by finer grained magnesium carbonate mudstone, within strata in the 9White Rock9, would be strong evidence of a photosynthetic microbial genesis. Another deposit of white rock on the western margin of Juventae Chasma could have a similar origin.

The lateritic nickel ore sample subjected to this experimental study was taken from Karacam ore deposit (Eskisehir-Turkey) and contains 1.80% Ni, 23.90% Fe, 1.58% Mg and 0.034% Co. According to the mineralogical analysis of lateritic nickel ore samples, goethite, hematite, wustite, retgersite, gaspeite, quartz and clay type minerals were observed. The leaching conditions of lateritic nickel ore in a nitric acid medium were investigated by studying the effects of its leaching parameters, such as stirring speed, temperature, nitric acid concentration and the particle size of the sample on Ni extraction. The maximum nickel extraction was obtained with the following conditions: 200 rpm stirring speed, 10/500 g/mL solid/liquid ratio, 240 min of leaching time, a 2.0 M nitric acid concentration, 80°C leaching temperature and -38 μm particle size fraction.

Salda Golu (Lake), in southern Turkey, is a highly alkaline (pH > 9) freshwater lake in which composite stromatolites several metres high are formed by microbially induced precipitation of hydromagnesite. The magnesium and carbonate in the lake waters were dissolved during passage through ultramafic rocks. Precipitation is brought about by the flora of diatoms and cyanobacteria forming the surface of the stromatolites, but does not occur in direct contact with cells. Stromatolites have previously been reported from environments ranging from fully marine through brackish water to a variety of freshwater lacustrine and fluvial situations. The principal importance of these structures lies in their novel mineralogy. Hydromagnesite Mg4(OH)2(CO3)3· 3H2O is commonly regarded as a low-temperature hydrothermal mineral.

F or the last fifteen years, there has been extensive motorway and railway constructions in Turkey. This requires enormous amount of road-fillers and aggregates, and the construction companies open many open-pit limestone quarries to fulfill their aggregate needs. The partly double four lines , partly one-way double line motorway of KonyaHüyük have recently been enlarged and partly re-constructed. During this construction, a total of five limestone quarry were opened to produce limestone aggregate. The Bozlutepe Limestone member of Asmalıtepe Formation near the town of Selki HüyükKonya, central Anatolia were used for this demand, and it has been operated for the last 6 years. The limestone member is approximately 200 m thick at most and mostly made of three type of minerals and these are dolomitic limestone, crystalline limestone and quartz-bearing crystallized limestones. All the minerals are crystallized and the minerals locally dominate at the quarry. The produced aggregates have relatively flat granulometry curve indicating most of the grains are of thin and have clay-silt sized particles. Our studies revealed that Bozlutepe Limestones are formed in carbonate facies in shallow marine environments during Permian-Carboniferous times. The member most likely have low-grade metamorphism during Paleozoic and Mesozoic eras