In recent years, it has been recognised that a better understanding of processes involving particulate material is necessary to improve manufacturing capabilities and product quality. The use of Discrete Element Modeling (DEM) for more complicated particulate systems has increased concordantly with hardware and code developments, making this tool more accessible to industry. The principal aim of this project was to study DEM capabilities and limitations with the final goal of applying the technique to relevant Johnson Matthey operations. This work challenged the DEM numerical technique by modelling a mixer with a complex motion, the Turbula mixer. The simulations revealed an unexpected trend for rate of mixing with speed, initially decreasing between 23 rpm and 46 rpm, then increasing between 46 rpm and 69 rpm. The DEM results were qualitatively validated with measurements from Positron Emission Particle Tracking (PEPT), which revealed a similar pattern regarding the mixing behaviour for a similar system. The effect of particle size and speed on segregation were also shown, confirming comparable results observed in the literature. Overall, the findings illustrated that DEM could be an effective tool for modelling and improving processes related to particulate material.

Active Screen Plasma Nitriding (ASPN) is a novel surface engineering technique, the main advantage of which is the capacity to treat homogeneously all kind of materials surfaces of any shape. Here, ASPN is used to modify the surface properties of ionomer glasses and polymers in order to improve the surface cellular compatibility of these materials. A conventional DC nitriding unit has been used together with an AS experimental arrangement. The materials that were treated were an ionomer glass composition and UHMWPE. All treated/untreated samples were seeded with the 3T3 fibroblasts. In order to identify the effect of the plasma treatment, chemical and mechanical properties characterization was conducted. For the cellular samples, SEM, Interferometry, AFM and MTT assay were conducted in order to observe cells’ behavior on the untreated and treated materials. The inert surface of the untreated glass showed good interaction with fibroblasts only after the ASPN treatment which resulted in enhanced fibroblasts attachment and proliferation. The treatment temperature, the length of treatment and the presence of nitrogen had an influence on the surface properties of glass. UHMWPE treated samples chemical characterization showed the formation of C-N and N-H groups resulting in an increase of the functionality of treated surfaces. 3T3 fibroblasts cell culture studies showed that the ASPN treatment had a positive effect on the adhesion and proliferation of cells according to the time of treatment and the increase of the nitrogen concentration in the gas mixture. As a conclusion ASPN treatment can be a very effective method to modify inorganic and organic polymeric surfaces in order to improve cellular compatibility.

The analysis presented in this thesis provides a methodology for grouted bolts design, based on empirical and analytical methods. Hence, the main objectives of this thesis are to offer practical means for better characterisation of poor to very poor rock masses, to better predict support pressure, and to develop an elasto-plastic analytical model for design of grouted bolts in tunnels excavated in such rock masses. To improve the applicability of the GSI (Geological Strength Index) in poor to very poor rock masses, using Broken Domain Structure (BSTR), Structure Rating (SR), and Intact Core Recovery (ICR), some modifications have been offered, resulting in the Modified-GSI. Applying rock-load height concept and Modified-GSI, an approach to estimate support pressure has been developed. The main advantage of this approach is its applicability in squeezing ground and anisotropic stress conditions. Numerical modelling was carried out in order to adjust the proposed support pressure equation. Considering convergence reduction approach, an elasto-plastic model based on the latest version of Hoek- Brown failure criterion has been developed for a more effective and practical grouted bolt design. The link between empirical approach and elasto-plastic solution makes it possible to reach more realistic and appropriate bolting pattern design. In this way, the need for the redesign procedure in the convergence reduction approach is eliminated. The results of the proposed elastic-plastic solution have been compared with a numerical model using FLAC2D, and a reasonable agreement was observed. The practical application of the developed methodology is depicted by an analysis of a case study in Turkey.

Obtaining high magnetic susceptibility phases from Hekimhan&amp / #8211 / Deveci siderite orevia preliminary thermal treatment has been the basic target of the thesis study.Thermal decomposition characteristics of samples, determined bythermogravimetric analysis (TGA), differential thermal analysis (DTA), and differential scanning calorimetry (DSC), were referenced in advancement of thestudy. Heat treatment experiments, particularly roasting, were carried out byconventional heating and microwave heating. Results showed that roasting of Hekimhan&amp / #8211 / Deveci siderite samples could not be achieved by microwave energywhilst conventional heating experiments recorded success. Subsequentlow&amp / #8211 / intensity magnetic separation of roasted samples gave recovery above 90%, where low&amp / #8211 / intensity magnetic separation of run&amp / #8211 / of&amp / #8211 / mine sample had failed. Formation of high magnetic susceptibility phases was verified by magneticsusceptibility balance and x&amp / #8211 / ray diffraction analysis (XRD), on roasted samples. Statistical modeling was applied to determine the optimum conditions of roastingin conventional heating system / based on heating temperature, time of heating, particle size as factors.It was concluded that roasting at T= 560 &ordm / C, for t= 45 minutes was adequate toobtain desired results. Particle size was noted to be not much effective on the process as other factors at the studied size range. Kinetics (E, n) and reaction mechanism for the thermal decomposition in conventional heating system were evaluated with different solid&amp / #8211 / state reaction models by interpretation of the model graphs.Three&amp / #8211 / dimensional diffusion reaction models reported to characterize the thermal decomposition well, with values of activation energy (E), E= 85.53 kJ/mol (Jander) / E= 85.49 kJ/mol, (Ginstling&amp / #8211 / Brounshtein).

Directional and horizontal drilling operations are increasingly conducted in all over the world, especially parallel to the growth of the technological developments in the industry. Common application fields for directional and horizontal drilling are in offshore and onshore when there is no way of drilling vertical wells. During directional and horizontal well drilling, many additional challenges occur when compared with vertical well drilling, such as limited weight on bit, harder hole cleaning, trajectory control, etc. This makes even harder to select the proper drilling parameters for increasing the rate of penetration. This study aims to propose a rate of penetration model considering many drilling parameters and conditions. The proposed model is a modified Bourgoyne &amp / Young&rsquo / s model which considers formation compaction, formation pressure, equivalent circulating density, and effective weight on bit, rotation of the bit, bit wear, hole cleaning, inclination, fluid loss properties and bit hydraulics. Also, a bit wear model is developed for roller cones and PDCs. The model performance is tested using field data obtained from several directional and horizontal offshore wells drilled at Persian Gulf. It is observed that the model can estimate rate of penetration with an error of &plusmn / 25 % when compared with the field data.

Semi-circular specimens (SCB) under three point-bending which are commonly used for fracture testing of rocks were used here for fracture mechanics tests. A total of 65 specimens were tested by using Ankara andesite rock. Investigations including the effects of initial notch thickness, different loading span ratios (S/R), flattened loading end, and little dimensional variations when preparing the specimens were carried out. Stress intensity factors for specimens with different geometries were computed individually by using a 3D finite element program ABAQUS. Specimens with a preliminary notch thickness varying from 0.84 to 3.66 mm were tested under three point bending. For a second group of specimens loading span was changed and fracture toughness variation was studied. Another change in the specimen geometry was made by machining a flat loading end at the upper load application point. Fracture toughness values were computed using the stress intensity values computed from numerical modeling and failure loads from the experiments. It was found that up to 2 mm fracture toughness was not affected by variations in the thickness of preliminary notches. Fracture toughness was not affected by changing the loading span. For specimens with flat loading ends, fracture toughness was about 16% lower than the value found from regular SCB type specimens loaded at a point at the top by a steel roller. As a result of about 46 experiments average fracture toughness of Ankara G&ouml / lbasi andesite was found as 1.36 MPa .

Most of the coal properties depend on carbon content and vitrinite reflectance, which are rank dependent parameters. In this study, a new approach was followed by constructing a simulation input database with rank-dependent coal properties published in the literature which are namely cleat spacing, coal porosity, density, and parameters related to strength of coal, shrinkage, swelling, and sorption. Simulations related to enhanced coalbed methane (ECBM) recovery, which is the displacement of adsorbed CH4 in coal matrix with CO2 or CO2/N2 gas injection, were run with respect to different coal properties, operational parameters, shrinkage and swelling effects by using a compositional reservoir simulator of CMG (Computer Modeling Group) /GEM module. Sorption-controlled behavior of coalbeds and interaction of coal media with injected gas mixture, which is called shrinkage and swelling, alter the coal properties controlling gas flow with respect to injection time. Multicomponent shrinkage and swelling effects were modeled with extended Palmer and Mansoori equation. In conclusion, medium-volatile bituminous coal rank, dry coal reservoir type, inverted 5-spot pattern, 100 acre drainage area, cleat permeability from 10 to 25 md, CO2/N2 molar composition between 50/50 % and 75/25 %, and drilling horizontal wells rather than vertical ones are better selections for ECBM recovery. In addition, low-rank coals and dry coal reservoirs are affected more negatively by shrinkage and swelling. Mixing CO2 with N2 prior to its injection leads to a reduction in swelling effect. It has been understood that elastic modulus is the most important parameter controlling shrinkage and swelling with a sensitivity analysis.

Shear strength characterization of discontinuities is an important concept for slope design in discontinuous rocks. This study presents the development of a methodology for implementing Barton-Bandis empirical shear strength failure criterion in three dimensional distinct element code, 3DEC, and verification of this methodology. Normal and shear deformation characteristics of discontinuities and their relations to the discontinuity surface characteristics have been reviewed in detail. First, a C++ dynamic link library (DLL) file was coded and embedded into 3DEC for modelling the Barton-Bandis shear strength criterion. Then, a numerically developed direct shear test model was used to verify the normal and shear deformation behaviour with respect to empirical results of the Barton-Bandis shear strength criterion. A three dimensional simple discontinuous rock slope was modelled in 3DEC based on Barton-Bandis shear strength criterion. The slope model was first utilized by Mohr-Coulomb failure criterion. Then, with the use of the new model developed here, the effects of the discontinuity surface properties on shear strength were introduced to the slope problem. Applicability of the developed model was verified by three large scale real case studies from different open pit lignite mines of Turkish Coal Enterprises (TKi), namely Bursa Lignites Establishment (BLi) &ndash / 2 cases and &Ccedil / an Lignite Establishment (&Ccedil / Li). The results with the new model option, which allows users to use important discontinuity surface properties like joint roughness coefficient and joint wall compressive strength, compared well with results of previous studies using Mohr-Coulomb failure criterion.

Groundwater can be a critical issue to be considered in civil engineering, mining engineering and interdisciplinary fields. Karstic structures and aquifers enclosing groundwater are potential risks in case they are not studied in detail. Enclosed groundwater can result in floods at pit bottom or can cause instabilities of permanent pit slopes. This study is about analyses of flooding possibility at the pit bottom and possible instabilities of pit slopes in the Elbistan-&Ccedil / &ouml / llolar open cast coal mine due to the presence of a karstic aquifer under the lignite formation. Thickness and permeability of the bottom clay formation under the lignite bed are necessary critical parameters for investigating a possible water rush from a confined aquifer in limestone formation underneath the bottom clay. These parameters were changed, and water flow quantities towards the pit bottom were determined by finite element models. Critical values of these parameters were investigated considering the lack of accurate site investigation information regarding the thickness and permeability of bottom clay. Possible strength loss, fracturing, and thus permeability increase in bottom clay due to a confined aquifer were studied. In flooding and slope stability analyses Phase2 software based on finite element method is used. Results of analyses showed that as reported thickness of bottom clay is around 120 m at the pit bottom and permeability values are in orders of magnitudes of 10-8 m/s, no serious flooding problems are expected to occur unless the thickness of bottom clay layer drops down to around 20 m, and the permeability of this layer reaches an order of magnitude of 10-5 m/s. Mechanical effects of confined aquifer on slopes and bottom clay displacements were investigated, and thus fracturing and failure possibilities of bottom clay and permanent slope were assessed. Slope and pit bottom displacements increased to meter levels for less than 60 m bottom clay thicknesses. Whereas 50-60 m bottom clay thickness can be critical for cracking, 20 m bottom clay thickness was found to be critical for water rush to the pit bottom. With reported bottom clay thickness of 120 m and with 25o slope angle permanent slope factor of safety was found to be 1.2, and this value was not effected unless clay layer thickness drops below 70 m levels. Higher than 32o overall slope angle there will be a risk of slope failure for permanent and production slopes, reflected by safety factors less than one, in the stability analyses.

Kirka Boron Plant in Eski