Determination of collector chemicals from flotation process waters using capillary electrophoresis

Vaahdotusprosessia käytetään yleisesti erottamaan arvokkaita mineraaleja malmeista. Toimiakseen tehokkaasti prosessi tarvitsee kokoojakemikaaleja, joiden tehtävänä on sitoa halutut mineraalit ilmakupliin. Jotta näiden kemikaalien käyttäytymistä prosessissa voitaisiin ymmärtää paremmin ja prosessin ohjausta tehostaa, pitää kokoojia pystyä analysoimaan prosessivesistä. Työn kirjallisuusosassa on koottu ja vertailtu erilaisia kirjallisuudesta löytyneitä analyysimenetelmiä kokoojakemikaaleille. Kokeellisessaosassa on kehitetty kaksi kapillaarielektroforeesimenetelmää näiden kemikaalien tutkimiseen. Menetelmien toteamisrajat tutkituille kemikaaleille olivat seuraavanlaiset: natrium diiosobutylditiofosfaattille (DTP) 2,7 mg/L puhtaassa vedessä ja 6,7 mg/L prosessivedessä; natrium diisobutyldithiofosfinaatille (DTPI) vastaavasti 4,5 mg/L ja 6,7 mg/L; etyyli ksantaatille 0,025 mg/L ja 0,16 mg/L; ja isobutyyli ksantaatille 0,41 mg/L ja 0,62 mg/L. Näitä menetelmiä voidaan tulevaisuudessa kehittää kokoojien hajoamistuotteiden analysointia varten sekä prosessien on-line mittauksiin.

On-line determination of residual collector concentration in flotation process

Valuable minerals can be recovered by using froth flotation. This is a widely used separation technique in mineral processing. In a flotation cell hydrophobic particles attach on air bubbles dispersed in the slurry and rise on the top of the cell. Valuable particles are made hydrophobic by adding collector chemicals in the slurry. With the help of a frother reagent a stable froth forms on the top of the cell and the froth with valuable minerals, i.e. the concentrate, can be removed for further processing. Normally the collector is dosed on the basis of the feed rate of the flotation circuit and the head grade of the valuable metal. However, also the mineral composition of the ore affects the consumption of the collector, i.e. how much is adsorbed on the mineral surfaces. Therefore it is worth monitoring the residual collector concentration in the flotation tailings. Excess usage of collector causes unnecessary costs and may even disturb the process. In the literature part of the Master’s thesis the basics of flotation process and collector chemicals are introduced. Capillary electrophoresis (CE), an analytical technique suitable for detecting collector chemicals, is also reviewed. In the experimental part of the thesis the development of an on-line CE method for monitoring the concentration of collector chemicals in a flotation process and the results of a measurement campaign are presented. It was possible to determine the quality and quantity of collector chemicals in nickel flotation tailings at a concentrator plant with the developed on-line CE method. Sodium ethyl xanthate and sodium isopropyl xanthate residuals were found in the tailings and slight correlation between the measured concentrations and the dosage amounts could be seen.

Determination of potential value drivers by identifying customer expectations and perceived value

The purpose of this exploratory research is to identify the potential value drivers regarding a new service offering. More specifically, the aim is to build understanding of customer expectations and perceived value of energy efficiency solutions in the building’s sector. The knowledge is then used in defining potential value drivers. The research is conducted from the customer’s perspective in a business-to-business context. The theory part of the master’s thesis focuses on discussing the antecedents of customer expectations and customer value. The theory gives implications how to determine value drivers and develop value propositions as well as conduct value assessment. The empirical part is based on the qualitative research method. The research was conducted as a single-case study, and the primary data was collected through semi-structured interviews with potential customers. The results of the research revealed that the customer expectations are connected to being able to define value drivers. In addition, the research revealed generic themes relating to the offering and customer-supplier relationship, which help in the process of identifying potential value drivers. The results were discussed in terms of product-, service-, price- and relationship-related value drivers for the new service. Based on the data analysis the dominant value drivers are elaborated in terms of identified customer benefits and customer sacrifices (costs). Finally, some implications of value proposition and value assessment to support the value delivery were given.

Determination of the thermal parameters of high-power batteries by local heat

A new approach to the determination of the thermal parameters of high-power batteries is introduced here. Application of local heat flux measurement with a gradient heat flux sensor (GHFS) allows determination of the cell thermal parameters in di_erent surface points of the cell. The suggested methodology is not cell destructive as it does not require deep discharge of the cell or application of any charge/discharge cycles during measurements of the thermal parameters of the cell. The complete procedure is demonstrated on a high-power Li-ion pouch cell, and it is verified on a sample with well-known thermal parameters. A comparison of the experimental results with conventional thermal characterization methods shows an acceptably low error. The dependence of the cell thermal parameters on state of charge (SoC) and measurement points on the surface was studied by the proposed measurement approach.

In Search for the European solidarity: The rule of law within the European Union in the framework of constitutional pluralism

The dissertation examines the rule of law within the European Union in the theoretical framework of constitutional pluralism. The leading lines of constitutional pluralism are examined with relation to the traditional and prevailing, monistic and hierarchical conceptions on how to perceive legal orders in Europe. The theoretical part offers also historical perspective by highlighting some of the turning points for the Union constitutional legal order in the framework of European integration. The concept of rule of law is examined in legal terms and its meaning to the Union constitutional constellation as a constitutional principle and a common value is observed. The realization of the rule of law at supranational and national level is explored with a view to discover that recent developments in some of the Member States give rise to concern about the viability of the rule of law within the European Union. It is recognized that the inobservance of the rule of law at national level causes a threat to the supranational constitutional legal order. The relationship between the supranational and national legal orders is significant in this respect and therefore particularly the interaction between the Court of Justice of the European Union (hereinafter the ECJ) and the Member States’ (constitutional/supreme) courts takes focus. It is observed that functioning dialogue between the supranational and national courts based on mutual respect and judicial deference is an important prerequisite for the realization of the rule of law within Europe. In order to afford a concrete example, a recent case C-62/14 Gauweiler v Deutscher Bundestag is introduced and analysed in relation to the notorious relationship between the Federal Constitutional Court of Germany and the ECJ. The implications of the ECJ’s decision in Gauweiler v Deutscher Bundestag is assessed with reference to some of the pressing issues of constitutionalism within Europe and some institutional aspects are also brought forward. Lastly, the feasibility of constitutional pluralism as a theoretical setting is measured against the legal reality of today’s Europe and its many constitutions. The hierarchical idea of one ultimate source of power, stemming from the traditional approaches to legal systems, is then assessed with relation to the requirement of the realization of the rule of law within the European Union from the supranational and national point of view.