Jalometallien reaktiomekanismit kuparikivi-kuona systeemissä

The amount of WEEE generated annually is growing, and effective means of recycling are required, in order to sustainably handle the growing waste quantity. WEEE is not only considered waste, but also a secondary resource of materials, including precious metals. Electronic devices can contain precious metals more than their respective primary ores, which in many cases are depleting. Pyrometallurgical methods of WEEE recycling are advantageous, because the processes can accept many forms of scrap and there are existing facilities for WEEE smelting. Downside of pyrometallurgical recycling route is the environmental concern that arises from high level of energy consumption. In this thesis, the time-dependent behaviour of precious metals in copper matte-slag system in simulated copper flash smelting conditions is studied. In the literature survey, the distributions of precious metals in equilibration studies were investigated. In the experimental part, the behaviour of precious metals is studied in air and argon atmospheres. Precious metals selected for this work are gold, silver, platinum and palladium. Compositional data was acquired with SEM-EDS, EPMA and LA-ICP-MS. The analyses indicated that the precious metals favour the copper and iron-bearing phases over slag phase and that formation of precious metal droplets and migration to matte phase begin almost instantly, when the system reaches high temperature. Precious metals concentrated in the matte phase as large droplets or smaller cluster distributed in the matte. There was significant scatter in the results with 300 s and 20 min contact time in air and argon atmospheres, respectively. For future work, it is suggested that the contact times in the proximity of 300 s in air atmosphere and 20 min in argon atmosphere are studied in more detail. The scatter in the results suggest the existence of some rate-limiting factor. In addition, the chemical dissolution behaviour of precious elements and their possible existence as sulphides in matte would require more detailed analysis. The formation of large precious metal droplets in air atmosphere should be studied further and the analysis of sample cross sections should be more extensive in order to find possible large droplets.Muodostuvan sähkö- ja elektroniikkaromun määrä kasvaa vuosittain ja tämän kasvavan jätemäärän kestävä käsittely vaatii tehokkaita kierrätysmenetelmiä. Elektroniikkaromua ei nähdä pelkästään jätteenä, vaan myös sekundäärisenä raaka-aineresurssina esimerkiksi jalometallien osalta. Elektroniset laitteet voivat sisältää jalometalleja enemmän kuin niiden primääriset malmit, jotka ovat monissa tapauksissa köyhtymässä. Pyrometallurgiset prosessit ovat edukkaita elektroniikkaromun kierrätysmenetelmiä, koska niiden syötemateriaalina voidaan käyttää monia eri romulajeja, ja romun käsittelyyn on jo olemassa olevia laitoksia. Pyrometallurgisten kierrätysmenetelmien haittana on suuresta energiankulutuksesta aiheutuva ympäristörasite. Tässä diplomityössä on tutkittu jalometallien ajasta riippuvaa käyttäytymistä kuparikivi-kuona -systeemissä kupariliekkisulatusuunissa vallitsevissa olosuhteissa. Kirjallisuusosuudessa tarkasteltiin jalometallien jakautumista tasapainotuskokeissa. Kokeellisessa osuudessa jalometallien käyttäytymistä tutkittiin ilma- ja argon-atmosfäärissä. Työhön valitut jalometallit olivat kulta, hopea, platina ja palladium. Näytteiden koostumusta analysoitiin SEM-EDS:lla, EPMA:lla sekä LA-ICP-MS:lla. Työn tulokset toivat ilmi, että jalometallit suosivat kuparikivifaasia kuonan sijaan, ja jalometallipisaroiden muodostuminen sekä jalometallien siirtyminen kivifaasiin alkavat lähes välittömästi, kun systeemi saavuttaa korkean lämpötilan. Jalometallit esiintyivät suurina pisaroina tai dispersioina jakautuneena kivifaasiin. Tuloksissa havaittiin merkittävää hajontaa 300 sekunnin ja 20 minuutin kontaktiajoilla ilma- ja argon-atmosfäärissä. Jatkotutkimuksiksi ehdotetaan kontaktiaikojen lisäämistä 300 sekunnin (ilma-atmosfääri) ja 20 minuutin (argon-atmosfääri) läheisyydessä. Tulosten hajonta viittaa jonkin reaktionopeutta rajoittavan tekijän olemassaoloon. Lisäksi jalometallien kemiallinen liukenemiskäyttäytyminen ja jalometallien mahdollinen esiintyminen kivessä sulfideina vaatii yksityiskohtaisempaa analyysiä. Suurten jalometallipisaroiden muodostusta ilma-atmosfäärissä ehdotetaan tutkittavaksi lisää, ja useampia näytteiden poikkileikkauksia tulisi tarkastella jalometallipisaroiden löytämiseksi

Varajärjestelmä taksien kyydinvälitykseen

Opinnäytetyön aiheena oli varajärjestelmä taksien kyydinvälitykseen. Tällä hetkellä pääjärjestelmän kaatuessa takseille välitetään kyytejä käyttämällä WhatsApp-nimistä sovellusta. Työn toimeksiantajana toimi OTaksi, vanhalta nimeltään Oulun aluetaksi. OTaksin yhteyshenkilönä toimi OTaksin toimitusjohtaja Vesa Tuunainen. Työn tavoitteena oli luoda toimiva prototyyppi varajärjestelmästä, ja ladata se pilvipalveluun. Opinnäytetyön tekijälle annettiin seuraavat vaatimukset järjestelmää koskien: järjestelmään täytyy pystyä syöttämään kyytejä ja kyydeissä täytyy näkyä asiakkaiden tiedot. Asiakkaiden tietoihin kuuluu mm. osoite, nimi, kellonaika sekä muu informaatio kuten puhelinnumero. Taksikuskien täytyy pystyä joko valitsemaan kyyti järjestelmästä tai kyyti välitetään suoraan lähimmälle kuskille. Järjestelmään täytyy kirjautua ennen käyttöä ja asiakkaiden tietojen täytyy olla turvassa. Opinnäytetyön tekijälle annettiin teknisen puolen toteutuksessa todella vapaat kädet, eikä hänellä ollut muuta tietoa kuin että OTaksin omistamat palvelimet ovat Windows-palvelimia. Työn tuloksena saatiin luotua toimiva varajärjestelmä, mutta ilman henkilöllisyyden todentamista. Tästä syystä johtuen työtä ei laitettu pilvipalveluun ollenkaan, eikä aika siihen olisi riittänytkään. Työhön oli jo tässä vaiheessa kulunut yli 400 tuntia. Opinnäytetyöhön tehtiin kaksi asiakassovellusta, serverirajapinta, tietokanta sekä taustapalvelu, joka päivittää tietokantaa noin minuutin välein. Yksi asiakassovellus toteutettiin Androidilla ja toinen WPF-sovelluksena. Rajapinta tehtiin käyttämällä ASP.NET Corea ja tietokanta käyttämällä MongoDB:tä. Taustapalvelu tehtiin .NET Core -konsolisovelluksena.The subject of this thesis was a backup system for the distribution of fares for taxis. The orderer of this thesis subject was OTaxi, a taxi company in Oulu, Finland. The goal of this thesis was to create a working back up system in case the main system ever went down. The last time this happened the jobs got distributed by a mobile texting app called WhatsApp. The requirements for this project were that jobs can be inserted into the system and the system either finds the closest car or the drivers can pick the jobs themselves. Other requirements were that there needs to be an authentication system in place and the customer information needs to be secure. Job has three to four attributes; time the job was created, address, customer name and any extra info that needs to be delivered to the driver. The developer was given a free reign over pretty much all the technical aspects of the project. Only thing that was known, is that OTaxi has some Windows-servers and this project could possibly be hosted there. As a result of this project a working prototype was created but without authentication services. Because of this the project cannot be deployed just yet. The project has two clients, an API, database and a background service that calls the database every minute and 15 seconds. One of the clients was made with Android and the other as a WPFapplication, meaning a desktop application for Windows devices. The API was created using ASP.NET Core. MongoDB was used as a database. Background service got created as a simple .NET core console application

Exploring the Relationship between Law Students’ Prior Performance and Academic Achievement at University

As Finnish university admissions are reformed, more information is needed on the relationship between performance in prior education and later academic achievement. Transition to university is a critical period, and low performance in prior education is associated with challenges in later study. In the present study, law students’ (n = 426) performance in the National Matriculation Examination was investigated in relation to later academic achievement at university. Quantitative methods were used. Findings showed that prior performance was not only associated with study success but also with study progress. The results also showed that law students who had grades in the advanced mathematics course were faster and more successful at university. This work contributes to the existing knowledge of university admissions ahead of the Finnish reform by providing new insights into prior performance and how it is related to academic achievement at university

Exploring the Relationship between Law Students’ Prior Performance and Academic Achievement at University

As Finnish university admissions are reformed, more information is needed on the relationship between performance in prior education and later academic achievement. Transition to university is a critical period, and low performance in prior education is associated with challenges in later study. In the present study, law students’ (n = 426) performance in the National Matriculation Examination was investigated in relation to later academic achievement at university. Quantitative methods were used. Findings showed that prior performance was not only associated with study success but also with study progress. The results also showed that law students who had grades in the advanced mathematics course were faster and more successful at university. This work contributes to the existing knowledge of university admissions ahead of the Finnish reform by providing new insights into prior performance and how it is related to academic achievement at university

Exploring internal structure of a performance-based critical thinking assessment for new students in higher education

Critical thinking is a combination of complex cognitive skills that are used for purposeful thinking. It is important for the successful acquisition of disciplinary skills in higher education and thus, it is a valuable competency for a new student. The complex nature of critical thinking leads to challenges for its assessment even in performance assessments such as CLA+ International (Collegiate Learning Assessment). The aim with this study is to examine internal associations of a critical thinking assessment for new students in higher education. The sample consisted of 1469 first-year students in 18 higher education institutions in Finland. An open-ended performance task and multiple-choice tasks were used to assess six measures of critical thinking, namely analysis and problem solving, writing effectiveness, writing mechanics, scientific and quantitative reasoning, critical reading and critiquing an argument. Exploratory and confirmatory factor analyses were used to analyse the data. A latent component indicated by the measures derived from the performance task was identified. The measures derived from the multiple-choice tasks did not form a factorial structure. Multiple-choice questions are problematic in critical thinking assessment as they focus on individual skills instead of holistic use of skills. Implications for assessment development and higher education are discussed.Peer reviewe

Development of a test device for the evaluation of hydrodynamic lubrication in thrust bearings

Oil lubricated thrust and journal bearings are widely used in industrial machines such as in stone crusher applications. In this study, a laboratory-scale test device for the evaluation of hydrodynamic lubrication in thrust bearings is developed. In the test device, the normal load, rotation speed, lubricant supply temperature and inlet flow rate can be adjusted and measured continuously and independently. In addition, thrust plate temperature and friction torque can be measured. This allowed initial testing of the functionality of the transient hydrodynamic model, which had been developed earlier to enhance bearing design and the testing process. The results show that the trends of the measured and the calculated results correspond well. The absolute friction coefficient values are also in reasonable agreement. The obvious main cause for deviation of results is the oil temperature in the pad inlet, exact estimation of which, by theoretical or experimental means, is complicated

The challenge of position-taking in novice higher education students' argumentative writing

Argumentative writing is the central generic skill in higher education studies. However, students have difficulties in basic argumentation skills. Novice students do not necessarily receive adequate guidance, and their prior education may not have supported the requirements of higher education writing. Position-taking is at the core of argumentation, but students are often hesitant to make their point. Furthermore, they may have an incorrect and one-sided perception about an argument, leading them to avoid alternative positions in their argumentative writing. The study aims to explore starting level skills of novice students’ argumentative writing, namely their position-taking. The participants were 196 first-year students from diverse fields of study in two Finnish higher education institutions. They were required to solve a problem and write an argumentative essay based on five documents that were given to them. The essays were analyzed using qualitative content analysis applying abductive approach. Substantial variation was detected in students’ position-taking. We identified four groups of writers based on their position-taking. First two groups were more or less explicit in their position-taking. Most of the students (72%) belonged to these two groups. However, a minority of them were consistent in their position-taking. Writers in the third group (15%) implied their position, and writers in the fourth group (12%) stuck to summarizing sources without position-taking. The findings invite teachers to support novice students in their basic argumentation. Co-operation between faculty teachers and writing teachers is encouraged.Peer reviewe

An epidemiological perspective on the future of direct-to-consumer personal genome testing

Personal genome testing is offered via the internet directly to consumers. Most tests that are currently offered use data from genome-wide scans to predict risks for multiple common diseases and traits. The utility of these tests is limited, predominantly because they lack predictive ability and clear benefits for disease prevention that are specific for genetic risk groups. In the near future, personal genome tests will likely be based on whole genome sequencing, but will these technological advances increase the utility of personal genome testing? Whole genome sequencing theoretically provides information about the risks of both monogenic and complex diseases, but the practical utility remains to be demonstrated. The utility of testing depends on the predictive ability of the test, the likelihood of actionable test results, and the options available for the reduction of risks. For monogenic diseases, the likelihood of known mutations will be extremely low in the general population and it will be a challenge to recognize new causal variants among all rare variants that are found using sequencing. For complex diseases, the predictive ability of genetic tests will be mainly restricted by the heritability of the disease, but also by the genetic complexity of the disease etiology, which determines the extent to which the heritability can be understood. Given that numerous genetic and non-genetic risk factors interact in the causation of complex diseases, the predictive ability of genetic models will likely remain modest. Personal genome testing will have minimal benefits for individual consumers unless major breakthroughs are made in the near future