ABSTRACT HIGH PRESSURE ACID LEACHING OF TURKISH LATERITES Kaya, Serif M.Sc., Department of Metallurgical and Materials Engineering Supervisor: Prof. Dr. Yavuz A. Topkaya January 2011, 91 pages The aim of this thesis study was to investigate and find the most cost effective way of extracting nickel and cobalt into the pregnant leach solution (PLS) from G&ouml / rdes lateritic nickel and cobalt ore by means of sulphuric acid leaching under high temperature and high pressure conditions.The high pressure acid leach (HPAL) experiments were conducted with nontronitic and limonitic types of G&ouml / rdes lateritic nickel ore, respectively. Leaching experiments of nontronite ore have shown that almost all of the nickel and cobalt contained in the nontronitic ore were easily extracted into the (PLS). Therefore, the rest of the experiments were concentrated on difficult to leach limonitic sample when compared with the nontronitic one, and higher nickel and cobalt extractions were aimed to be obtained. By taking economic and technical considerations into account, the basic (HPAL) process parameters for the limonitic sample were optimized as / leaching at 255 &deg / C with a particle size of 100% -850 &mu / with 0.30 sulphuric acid to ore weight ratio in 1 hour of leaching duration. The experiments were conducted with 30% solids ratio and it was found that 87.3% of nickel and 88.8% of cobalt present in the limonitic ore could be extracted into the pregnant leach solution. Nevertheless, these results were found to be below the desired values. Therefore, the possible reasons of this behavior were investigated and the presence of hematite mineral in the limonitic ore was found to be the most probable one. Therefore, in order to dissolve the nickel and cobalt present in the hematite mineral, the additions of HCl, ferrous ions, cuprous ions and sulphur were tried, respectively and they were found to be beneficial in order to increase the degree of nickel and cobalt extractions.

The conventional cement grinding system, the ball mill, has very poor efficiencies in spite of innovative improvements. For this purpose, development of new techniques, which allow proper size reduction and uniform particle size distribution with less specific energy consumptions, have become a necessity. The aim of this study is to make a comparative analysis of the fairly new cement grinding technologies, COMFLEX&reg / Grinding System, Roller Press and HOROMILL&reg / , at the same cement production plant with the same raw materials. In this context, CEM I 42.5 R type cement was produced with a fixed Blaine fineness of 3600 (&plusmn / 100) cm2/g at three different grinding units. The same raw materials, clinker and gypsum, and identical feeding ratios, 95% and 5%, were used to produce cement. Accordingly, these different grinding techniques were inspected with respect to the microstructural properties of cement particles, and the relative chemical, physical and mechanical properties of products. It was found that the main cement grinding parameters, specific surface area and sieve residue, do not show expected relation and change with each grinding system due to differences in the size reduction technique. Moreover, strength and other hardened mortar properties are directly affected by the liberation conditions of reactive grains at grinding stages.High capacity and low specific energy consumption i.e. the breaking and cracking efficiency of the roller press and higher grinding performance of the ball mill promoted the COMFLEX&reg / system. On the other hand, the roller press was clearly advantageous at early strength performances with moderate specific energy usages during grinding. Nonetheless, it also had drawbacks like higher water demand and earlier setting times (which mean higher hydration temperatures). When the wideness and sharpness of classification results were considered, HOROMILL&reg / gave better results with high circulation and efficient air classification design / although there were weaknesses of the system such as lower capacity and higher specific energy consumption rate.

In recent years, the risks created by the import of energy on the security of energy supply has encouraged countries to utilize local resources to a greater extend, and for many countries including Turkey coal is at the top of the local resources. However, it is not sufficient for countries to have an energy resource itself. Intens competition in today&#039 / s globalized system requires the resources to be produced and utilized in the most economical manner. The supply of the resources to the market in a competitive way is possible by employing an efficient operation, which is then possible only through the business units producing these resources working efficiently. In this study, the efficiencies of the eight establishments of the Turkish Coal Enterprises (TKI) between 2006 to 2009 were analyzed by using Data Envelopment Analysis (DEA), Super Efficiency (SE) and Malmquist Total Factor Productivity Index (MI) methodologies. For the analyses, three output oriented models were constructed and used: Production Efficiency, Revenue Efficiency and Work Safety Efficiency models. In determining the input and output data used in the analyses, it was benefited from similar studies searched in the literature, knowledge of business and economics and a series of brainstorming of the expert panel consisting of ten high level representatives of the public and private lignite mining companies as well as that of the Turkish Ministry of Energy and Natural Resources. As a part of the analyses, first the production and revenue efficiencies of the establishments were analyzed by using Constant Return to Scale (CRS) and Variable Return to Scale (VRS) methods of DEA. Within this context, efficient and inefficient establishments for the years between 2006 to 2009, and benchmarks for inefficient establishments to move to becoming efficient were determined. Furthermore, for the production and revenue efficiency models, the target values and improvement potentials for the inefficient establishments in CRS analyses to becoming more efficient were calculated by using benchmarks tables and 2009 realized values of inputs and outputs. Second, the efficiency rankings of the efficient establishments among themselves between 2006 to 2009 were determined by using SE methodology. Third, to provide the dynamic analysis of the development of the establishments&#039 / s efficiency levels in time, the changes of production, revenue and work safety efficiencies of the establishments between 2006 to 2009 were analyzed using the Malmquist Index (MI) methodology. MI analyses included the analysis of the efficiencies in four efficiency components (Technical, Technological, Pure and Scale efficiencies) as well as the calculation of the Total Factor Productivity Indexes of the establishments.

As high grade iron ore deposits are rapidly depleted, the minerals industry is increasingly obliged to enrich their ores and process lower grade iron ores. Production of large quantities of fine ores as tailings or by-products in mining operations and mineral liberation at fine particle sizes have led to the development of concentration methods employed to fine ores. Selective flocculation is one of the beneficial methods which can be used in recovering of very fine particles It is obvious that process water chemistry has a significant influence on the flocculation efficiency, and the water chemistry is deeply affected by carbon dioxide dissolution. Carbonate content of natural waters regulated by CO2, carbonicacid and solid carbonatesis known as &lsquo / carbonate alkalinity&rsquo / whichmay be an important factor in flocculation especially at alkaline pH. Selective flocculation of iron ores is usually run at around pH 11 where carbonate alkalinity could be rather high. There have been no reports in literature regarding the effect of carbonate alkalinity on the flocculation behavior of iron oxides, mainly hematite. In this study, the flocculation behavior of iron ores with starch under different alkalinities has been investigated. The extent of flocculation has been assessed by settling rate and suspended solid content measurements at different starch doses and pH values. Zeta potential measurements and starch adsorption studies were carried out to explain these effects by carbonate alkalinity. According to the results, flocculation is enhanced by addition of low amount of carbonate alkalinity, less than 2.4 mEq/L. However, adding the higher amount of alkalinity adversely affected the flocculation of hematite. Similar behavior was also observed during the starch adsorption tests, larger amount of starch wasadsorbed by hematite in low alkalinity compared to high alkalinity. Zeta potential measurements indicate that, by increasing the carbonate alkalinity of suspension, zeta potential values of solids will become more negativeleading to an increase in the stability of suspension and then adversely affecting flocculation. Therefore, as carbonate alkalinity has a significant effect on the flocculation of hematite, it should be seriously taken into account to optimize the selective flocculation of hematite ores.

The main objective in this study is to compare breakage parameters of narrow size fractions of cement clinker taken from the product end and feed end of industrial-scale high pressure grinding rolls (HPGR) in order to assess whether the breakage parameters of clinker broken in HPGR are improved or not. For this purpose, drop weight tests were applied to six narrow size fractions above 3.35 mm, and batch grinding tests were applied to three narrow size fractions below 3.35 mm. It was found that the breakage probabilities of coarse sizes and breakage rates in fine sizes were higher in the HPGR product. This indicated that clinker broken by HPGR contained weaker particles due to cracks and damage imparted. However, no significant weakening was observed for the -19.0+12.7 mm HPGR product. Although HPGR product was found to be weaker than HPGR feed, fragment size distribution of HPGR product did not seem to be finer than that of the HPGR feed at a given loading condition in either the drop weight test or batch grinding test. Also, drop weight tests on HPGR product and HPGR feed showed that the breakage distribution functions of coarse sizes depended on particle size and impact energy (J). Batch grinding tests showed that the specific breakage rates of HPGR product and HPGR feed were non-linear which could be represented with a fast initial breakage rate and a subsequent slow breakage rate. The fast breakage rates of each size fraction of HPGR product were higher than HPGR feed due to cracks induced in clinker by HPGR. However, subsequent slow breakage rates of HPGR product were close to those of HPGR feed due to elimination of cracks and disappearance of weaker particles. Besides, the variation in breakage rates of HPGR product and HPGR feed with ball size and particle size also showed an abnormal breakage zone where ball sizes were insufficient to effectively fracture the coarse particles. Breakage distribution functions of fine sizes of HPGR product and HPGR feed were non-normalizable and depended on particle size to be ground. However, batch grinding of -2.36+1.7 mm and -1.7+1.18 mm HPGR feed yielded the same breakage pattern.

This thesis deals with the political economy of mining laws and regulation in Namibia from 1884 to 1986. Mining laws and regulations have played an important role in the exploitation of Namibia's mineral resources since the colonial period. They have also played an important role in the exploitations by foreign mining companies of Namibia's mineral resources. The study shows how this process has evolved. Chapter I discusses the link between colonialism and exploitation. It also shows the special interest of the colonial administration in mineral development. The formal and substantive rules governing the acquisition of mineral rights are discussed in detail in Chapter II. An important element in the exploitation of Namibia's mineral resources is the international market. Chapter III examines the marketing of Namibia's minerals. It shows that the colonial administration is unable and unwilling to exercise control in this area. Special attention is paid to the marketing of diamonds as it illustrates very well the dominant position of the mining companies. Marketing of minerals is closely linked with taxation. This is examined in Chapter IV. The chapter reveals that the inadequacies of the legislation enables mining companies to achieve their objective, maximisation of profits without corresponding benefits to Namibia. The exploitation of Namibia's mineral resources has a direct effect on the environment. Chapter V shows that the spread of multinational mining companies and their operations have a direct effect on the environment, health and safety of mine employees and the community in surrounding areas. It also shows that mining laws and regulations are inadequate to cope with this problem. South Africa's continued occupation of Namibia since the termination of the mandate in 1966 has important legal consequences. The legal status of the mining concessions granted by South Africa before and after the termination of the mandate are examined in Chapter VI in the light of the United Nations action in this respect. In order to clarify the options for independent Namibia, Chapter VII discusses the experience of other developing countries in mineral development and their relationship with multinational companies. In Chapter VII, we recommend that mining laws and regulations of an independent Namibia should reflect the needs of the Namibian population.

This thesis examines the impact of social and economic change on the practice of "free mining" in the Forest of Dean between 1788 and 1886, asking how and why the free miners' "rights" altered over that period and what the consequences of their survival were for the development of trade unionism among the Forest miners. The thesis is divided into three parts. The first of them discusses the free miners' rights and argues that they should be seen as part of a group of uses, including commoning and the occupation of Crown land, which its inhabitants made of the Forest in the eighteenth century. These uses came under pressure between 1788 and 1841 from reforms in central government and the intrusion of strangers from outside the Forest into the mining industry. A series of Acts of Parliament between 1838 and 1841 consolidated the new order in the Forest but the bargaining which preceded that legislation resulted in the preservation - though in a diluted form - of the miners' rights and of commoning. Part two asks whether the partial survival of these customs acted as a socially conservative influence which might have explained the relative weakness of trade unionism among the Forest's colliers. It is argued that the instability of union may be explained by reference to the organization of the industry and its markets, to the method of work organization in the pits, which created divisions among the miners, and to the inadequacies of "national" miners' unionism. Though it is not necessary to invoke the peculiar local rights and customs to account for the weakness of unionism in Dean, Part three will contend that they remained important to many foresters. Renewed pressure from the Crown and from the large coalowners, on both the free miners and commoners, and the resistance of the foresters to change, are examined. The character of that resistance took colour from the assumptions and rhetoric of the union and in turn reinforced and helped to make successful, a campaign by the union for the separate representation of the working men in the Parliament.

The most important criterion in industrial production processes is to control the required product quality and comply with the standards pre-described for the application during any stage of the process. This control begins from the entry of raw material to the plant and continues with pre-determined points. Mainly two different types of inspection and analyses are used to examine the material quality and content. These are physical and chemical analysis.In most of the production plants above mentioned analyses are made in related laboratories of the plant. Therefore, it is necessary to have &amp / #65533 / sample&amp / #65533 / to be analyzed. This &amp / #65533 / sample&amp / #65533 / should have a real &amp / #65533 / representative&amp / #65533 / property, which must carry all of the physical and chemical characteristics of the material at the point where this &amp / #65533 / sample&amp / #65533 / is taken.The present methods and systems used to take samples from any required point have some disadvantages and present some problems especially for not being &amp / #65533 / representative&amp / #65533 / . These problems are discussed in detail within this thesis study and aimed to reach a new concept and system with: - Low cost of investment - Low cost of operation - Less requirement of maintenance and calibration - The achievement of &amp / #65533 / correct&amp / #65533 / and &amp / #65533 / representative&amp / #65533 / sample As a result of the theoretical studies together with practical application works and experiments, a new concept in sampling, namely &amp / #65533 / Sampling System with Air Cannons&amp / #65533 / was introduced. The new system of sampling was tested to give better performance and practical use.

ABSTRACT MODELING A MODERN MARBLE PROCESSING PLANT BY USING PETRI NET Keser, &Ouml / zge M. Sc., Department of Mining Engineering Supervisor: Prof Dr. NeS&rsquo / e &Ccedil / elebi Co-Supervisor: Prof Dr. Tevfik G&uuml / yag&uuml / ler December 2003, 110 pages All developing countries need sufficient raw material resources to develop and to guarantee their future. Considering Turkish natural resources, marble has a great importance because of its demand on the market, reserve amount and quality. However, some effort is required to improve the existing marble production and processing efficiency. Petri nets (PNs) are the information models that control the flow for concurrent and synchronous systems. In this regard, PN application can be useful. However, its application is limited to the complex systems and no application of PN is available in mining sector. iii In this sense, this study aims to examine the applicability of PN to mining. This study examines the production system in order to optimize the process in case of two different types of marble product orders. Three case studies are applied to examine benefits and difficulties in implementation of PN to a marble processing plant. The study shows that PN can successfully be used as a tool for the optimization of total production time, simulation and modeling of the system. It provides to see the sequence of the processes, their time, remaining time of each transition and optimum total production times. The difficulties of PN implementation are found out as the determination of each path in the reachability graph, matrix representation with large quantity of place, etc.

Discontinuity surfaces generally consist of undulations termed as roughness. It is well known that surface roughness plays an important role on the shear strength and shear behavior of discontinuities. However, the effect of roughness will not be the same when the direction of shearing changes. This effect causes variation of shear strength with shearing direction or in other words anisotropy on shear strength. In this thesis, an experimental study was performed to investigate the effect of roughness and anisotropy on shear strength. For this purpose, joint samples were prepared using a model material and direct shear tests were conducted at different normal stress levels and shearing directions.