Leaching is the most widely used process for extraction of nickel metal from lateritic ores. In this study, nickel extraction from Manisa-G&ouml / rdes region laterites by hydrochloric acid leaching is aimed. The mineralogical analysis of sample showed that hematite, goethite, dolomite, quartz and smectite are the main minerals in the ore. Attrition scrubbing, cycloning and magnetic separation with permroll were used as preconcentration processes but results were unsatisfactory. HCl leaching experiments were conducted both at room temperature and at elevated temperatures. The effects of various parameters such as leaching duration, particle size, concentration of HCl, pulp density, Cl- concentration and temperature on nickel recovery were examined. The results showed that under the optimised leaching conditions (particle size: 100 % -1 mm, HCl concentration: 3 N, leaching duration: 3 hours, leaching temperature: 100 oC, pulp density: 1/30 solid to liquid ratio by volume) it was possible to extract 87.26 % of nickel in the ore.

Rare earth ferrosilicon alloy is an important additive for ferrous metallurgy. It is mainly used to control the detrimental effects of sulfur in steel and to modify graphite structures in cast iron. The aim of this study was to optimize the conditions for the production of rare earth ferrosilicon alloy by metallothermic reduction process using a preconcentrate prepared from a bastnasite type of ore present in the Beylikahir-EskiSehir region of Turkey. In this study, the rare earth preconcentrate was reduced by aluminum together with ferrosilicon and rare earth ferrosilicon alloys were produced. The optimum conditions of reduction, which are time, temperature, reducer amounts and the basicity of the slag phase, were investigated by smelting in an induction furnace. At the end of the study, a rare earth ferrosilicon alloy containing 39.3 % rare earths, 37.5 % silicon, 19.3 % iron and 3.9 % aluminum was produced under the optimum conditions determined with 57.7 % rare earth metal recovery.

Clinoptilolite is a natural zeolite which can be used favorably in heavy metal removal. The main mechanisms for metal removal via clinoptilolite are adsorption and ion exchange. Several sources propose to keep the normality constant to obtain equilibrium isotherms for ion exchange systems, while many studies use constant sorbent mass with varying normalities of the sorbate. The objective of this study is to investigate the prevailing mechanisms of clinoptilolite during cadmium removal and the impact of the methodology for obtaining equilibrium isotherms. Batch Cd2+ removal experiments were conducted by using the two different methodologies (i.e. keeping the sorbent mass constant vs. keeping the normality constant) with clinoptilolite in as-received (AsC) and conditioned form (CnC), an ion exchange resin and granulated activated carbon. Exchangeable and framework cations, conductivity and pH were monitored during experiments. The equilibrium results were then fitted to isotherm models. The prevailing mechanisms for Cd2+ removal with clinoptilolite are discussed considering all monitored parameters and isotherm model fits. Use of the methodology was seen to have an effect on the overall Cd2+-clinoptilolite interaction. For example, differences between methodologies are observed regarding maximum sorbed Cd2+ and the distribution of exchangeable cations. Conductivity profiles provided a good indication of presence of ion exchange and demonstrated that it is more dominating for CnC than for AsC. The Cd2+ removal capacities observed in this study (0.65 meq/g for AsC and 1.46 meq/g for CnC) are the highest recorded for a clinoptilolite sample, as can be found in the literature.

The marginal glass-forming alloys have attracted much attention due to unique products of devitrification with a very high number density of nuclei up to 10^23 m^-3. Among these alloy systems, utmost interest is given to Al-RE and Al-TM-RE alloys with excellent lightweight mechanical (fracture strength close to 1 GPa) and chemical properties attributed to the presence of an extremely high density of nanocrystals embedded in an amorphous matrix. Classical nucleation theory fails in explaining this abnormal nucleation behavior, several other mechanisms have been proposed / however, there is still no agreement on the exact nucleation mechanism. Al-Tb system was investigated in liquid and solid amorphous states with a collective study of ab-initio MD and RMC simulations and state of art X-rays and e-beam techniques. Regions of pure Al clusters in the solid and liquid states were detected with the sizes extending up to 1-2 nm length. Al clusters interconnecting regions lead to formation of RE rich MRO structure which gave rise to the pre-peak in S(Q)-Q data in liquid and solid states. Specimens having MRO were crystallized within a controlled atmosphere and temperature and investigated using a combined study of TEM, HRTEM, SEM, XRD and DSC. HRTEM investigations and JMA results indicated different mechanism of nucleation. Therefore the kinetics of highly populated nuclei formation was found too complicated to be explained by well-known JMA approach. Mechanical tests were applied to determine the effects of morphology and populations of nanocrystals embedded in amorphous matrix. The tensile tests and the subsequent fracture surface analysis indicated brittle type of failure and the formation of shear bands, respectively. Relatively high hardness and tensile strength were detected by nanocrystallization.

Main purpose of this study was to find the optimum conditions to produce a charge material for ferromanganese production or steelmaking with high content of iron and manganese carbides from Denizli-Tavas manganese ore by carbothermic reduction and investigate the effects of temperature, time, amount of active carbon addition and CaO addition on this reduction. The ore was calcined and then mixed with active carbon and CaO. Experiments were performed in a horizontal tube furnace that can be heated up to 1700 &ordm / C with MoSi2 heating elements. After each experiment weight loss data were obtained and converted to percentage reduction. X-Ray, SEM-EDS and chemical analyses were done in order to determine whether or not carbide phases have been obtained, and calculate the composition of the product. Considering the experimental results, the optimum conditions found for reduction of Denizli-Tavas manganese ore were 1250 &deg / C, 4 hours, 100% of stoichiometric amount of active carbon and 5% CaO addition. Under the optimum conditions 83.85% reduction of calcined ore was obtained.

The design and production of efficient metal-hydrides for hydrogen storage is a long standing subject. Over the years, many different types of intermetallic hydride systems were studied and some of them came out to be operable. However, none of them meet all the storage criteria perfectly. In this study, total energies, hydrogen storage capacity and stability of AB (A = Al, Be, Cu, Fe, Ni, Sb, V and B = Ti) type intermetallics were investigated with the goal of spotting a potential hydrogen storage material. The relation between thermodynamic properties and the atomic and the electronic structure of hydrides are also pointed out. For this task, first principles pseudopotential method within the generalized gradient approximation (GGA) to density functional theory (DFT) was used. Calculations correctly predict experimentally determined structures except for CuTiH. Moreover, the atomic and cell parameter were found within the allowable error interval for DFT. In CuTi intermetallic, a structure having considerably lower formation energy than experimentally found mono-hydride was determined. This contradiction may be due to metastability of the experimental phase and high activation energy for the hydrogen movement in the system. It was found that AlTi and SbTi are not suitable candidates for hydrogen storage since their hydrides are too unstable. For the other intermetallic systems, the stability of the hydrides decreases in the order of VTi, CuTi, NiTi, BeTi, FeTi. For VTi, FeTi and NiTi, a change in metallic coordination around hydrogen from octahedron to tetrahedron is predicted when tetra-hydride (MTiH4) is formed. Additionally, at this composition, FeTi and NiTi have hydride structures with positive but near-zero formation energy which may be produced with appropriate alteration in chemical makeup or storage parameters. VTi is a promising intermetallic by means of storage capacity in that even VTiH6 is found to have negative formation energy but the hydrides are too stable which can be a problem during hydrogen desorption.

Daily aerosol samples (PM) were collected at a rural station, which is 5 km away from the Turkish-Bulgarian border between April 2006 and March 2008. Aerosol samples were analyzed for elements by ICPMS, ions by IC and black carbon by aethalometer to provide a multi-species aerosol data set, which can represent aerosol population for Northwestern Turkey and Eastern Europe. Average concentration of SO42-, NO3- and NH4+ was 5.8, 2.9 and 2.0 &mu / g m-3, respectively, while total aerosol mass was 66 &mu / g m-3. Seasonal variation of crustal species had maxima in summer, while most of the anthropogenic species had maxima in winter. Rainfall was found as the only local meteorological parameter affecting aerosols concentrations. The dominant sectors of air masses arriving the Northwestern Turkey were northeast in summer and west-northwest in winter. Air masses were classified into five clusters regarding their wind speed and direction. Most species indicated significant differences between clusters. The influence of forest fires in Ukraine and Russian Federation was identified by cluster analysis using soluble K as tracer. Source apportionment of PM was carried out by EPA PMF model and five sources were resolved. Crustal emissions were found to be the major contributor to PM (41%). The second largest source was distant anthropogenic sources with a contribution of 26%. Traffic was also a remarkable source with 16% contribution. Sea salt and stationary combustion sources accounted for 9% and 8% of PM, respectively. Potential source regions of resolved sources were determined by potential source contribution function (PSCF).

The purpose of this study was to investigate the process optimization of combined high pressure acid leaching (HPAL) and mixed hydroxide precipitation (MHP) route for the extraction of nickel and cobalt from &Ccedil / aldag lateritic nickel ore. In order to extract nickel and cobalt values into pregnant leach solution (PLS), several process parameters of HPAL including acid load, temperature, leaching duration and particle size were investigated in comparative manner at constant solid concentration and agitation speed. After HPAL trials, it has been found that more than one combination of parameters offered higher than 90% extraction efficiencies for both nickel and cobalt. Among them, 0.325 kg/kg acid load, 250&deg / C, 1 hour duration and 100% -1 mm particle size was selected as the optimum conditions with 94.1% Ni and 94.0% Co extractions. A stock of PLS was prepared under the stated conditions that was treated by downstream operations in order to obtain MHP. Initially by two-stage iron removal of downstream operations major impurities iron, chromium and aluminum were nearly completely removed with acceptable nickel and cobalt losses from PLS. Then, the nickel and cobalt were precipitated by two-stage mixed hydroxide precipitation. In the first step of MHP, the optimum conditions were chosen as pH=7.10, 60&deg / C and 1 hour duration. The intermediate product obtained at these conditions contained 44.3% Ni, 3.01% Co with 3.06% Mn contamination. In summary, it was found that &Ccedil / aldag nickel laterite ore was readily leachable under HPAL conditions and PLS obtained was easily treatable in order to produce saleable MHP.