Luossavaara Kiirunavaara Aktiebolag (LKAB) är ett av Sveriges äldsta industriföretag som bedriver världens två största underjordsgruvor för järnmalmsbrytning och deras huvudprodukt är järnmalmspellets. Hög och stabil kvalitet är av stor vikt för LKAB, därav är kvalitetskontroll en av deras nyckelaktiviteter. För att fastställa kvaliteten på de produkter som levereras till företagets kunder görs en provtagning och analys av alla båtlaster som lämnar företagets hamnar. Provtagning sker löpande i samband med lastning, där flera primära prov tas ut i en provtagningsanläggning. De primära proven delas systematiskt ned i mindre mängder, blandas och genererar ett leveransprov. Leveransprovet används för att analysera lastens kemiska, metallurgiska och fysikaliska parametrar, där järnhalten ligger till grund för den specifika lastens slutpris. LKAB:s provtagningsanläggningar har designats enligt ISO 3082, där produktens kvalitetsvariation tillsammans med önskad provtagningsprecision ligger till grund för hur omfattande provtagningen bör vara. Om produktens kvalitetsvariation inte är känd ska den fastställas experimentellt med ISO 3084. Ett sådant försök har inte tidigare utförts av LKAB. I stället har företaget gjort egna antaganden kring kvalitetsvariation utifrån deras mångåriga erfarenhet av produkterna och ingenjörsmässiga bedömningar med utgångspunkt i historiska leveransdata. För att säkerställa att provtagningen sker i enlighet med ISO 3082 krävs en utvärdering av produkternas faktiska kvalitetsvariation. Utifrån produktens fastställda kvalitetsvariation kan därefter provtagningens befintliga precision bestämmas. Arbetet syftar till att besvara följande två frågeställningar:   1.    Hur stor är kvalitetsvariationen hos LKAB:s järnmalmspellets KPRS som lastas i Narviks hamn? 2.    Hur stor är precisionen vid provtagning i LKAB:s provtagningsanläggning Kai 7 i Narviks hamn? Försöket utförs på järnmalmspelletstyp KPRS med analyserna ISO 4700, ISO 11256, KTH 950, XRF, Fe HCl samt siktanalys. KPRS är en pellets avsedd för ståltillverkning med metoden direktreduktion. För de kvalitetsparametrar där variationens magnitud kan klassificeras i de ISO-standardiserade kategorierna liten, mellan eller stor, visar LKAB:s pellets på en liten variation. Variationen är till och med mycket liten och långt under klassifikationsgränserna. LKAB saknar interna krav för minsta accepterade precision vid provtagning, vilket inte gör det möjligt att bedöma den befintliga provtagningens duglighet. Som fortsatt arbete bör företaget därav fastställa interna krav på provtagningsprecision och även utvärdera befintlig precision för provberedning och mätning i enlighet med ISO 3085. / Luossavaara Kiirunavaara Aktiebolag (LKAB) is one of Sweden’s oldest industrial companies which operates the world’s two biggest iron ore underground mines, and their main product is iron ore pellets. High and stable quality is of high importance for LKAB, that is why quality control is one of their key activities. To determine the quality of the products delivered to their customers, sampling and analysis is conducted on all vessels leaving the company’s ports. Several primary samples are taken during the loading process by a sampling facility. The primary samples are systematically divided in smaller portions and mixed, called a shipment sample. The shipment sample is used to determine the lot’s chemical, metallurgical and physical quality characteristics and the iron content determines that specific lot’s price. The sampling facility and sampling scheme is designed according to the international standard ISO 3082. According to ISO 3082 the product’s quality variation together with desired sampling precision should determine the number of primary samples to be taken. If the quality variation is unknown, it should be determined in accordance with another standard: ISO 3084. A determination like this have not previously been made by LKAB. Instead, the company have made own assumptions about the quality variation based on their long experience of pellet production and historical delivery data. To reassure that the number of primary samples is collected in accordance with ISO 3082 an evaluation of the actual quality variation is needed. When the quality variation is determined, the current sampling precision can be defined. The master thesis aims to answer the two research questions:  1.    How big is the quality variation for LKAB: s iron ore pellets KPRS which are loaded at the port of Narvik? 2.    How good is the current sampling precision in Kai 7 at the port of Narvik? The attempt is made on iron ore pellet type KPRS with the analyzes ISO 4700, ISO 11256, KLH 950, XRF, Fe HCl and sieving. KPRS is a pellet made for steel manufacturing with the method direct reduction. For the quality characteristics where the variations’ magnitude can be classified into ISO 3082’s categories small, medium, or large, LKAB’s pellets turn out to have a small variation. The variation is actually very small and far below the standard’s classification limits. LKAB lack internal limits for sampling precision, which makes it impossible to determine the current sampling scheme’s capability. As future work, LKAB should therefore decide upon sampling precision limits. An evaluation of precision for sample preparation and measurement should also be made in accordance with ISO 3085.

[pt] As pelotas de minério de ferro são produzidas a partir de um processo de aglomeração de finos de minério denominado pelotização, e possuem granulometria adequada para utilização em fornos siderúrgicos. Nesta dissertação dois fenômenos associados às superfícies das pelotas foram estudados: a formação de trincas e a presença de recobrimento (coating). Durante a pelotização, as pelotas são submetidas a diversos esforços compressivos e mudanças bruscas de temperatura. Desta forma, são geradas trincas em sua superfície, que são prejudiciais à resistência e ao desempenho nos fornos de redução. Já durante o processo de redução pode ocorrer a formação de pontes de ferro entre as pelotas, que se aglomeram formando clusters que comprometem o fluxo de gases no interior dos fornos. Este problema pode ser minimizado recobrindo as pelotas com uma mistura a base de óxidos de magnésio, o coating, que inibe a formação das pontes. Tendo em vista a importância de caracterizar trincas e coating na superfície das pelotas, a presente dissertação desenvolveu metodologias de aquisição, processamento e análise digital de imagens adquiridas com um estereoscópio. Foram desenvolvidos porta-amostras ajustáveis que permitiram a aquisição de imagens 2D de pelotas aproximadamente esféricas de diferentes tamanhos, cobrindo a maior parte da superfície e evitando a sobreposição de regiões de análise. A rotina de análise de trincas comparou dois métodos de segmentação e forneceu atributos como espessura média, fração de área e comprimento. A rotina de análise de coating utilizou segmentação por limiarização e mediu a fração de área ocupada em cada pelota. O uso dos porta-amostras foi fundamental para o sucesso do procedimento de aquisição. As rotinas de análise de trincas ou de coating se mostraram robustas para diferentes amostras. / [en] Iron ore pellets are produced from an ore fines agglomeration process called pelletizing, and are suitable for use in steel furnaces. In this dissertation two phenomena associated with the pellet surfaces were studied: crack formation and the presence of coating. During pelletizing, the pellets undergo various compressive forces and sudden changes in temperature. In this way, cracks are generated on its surface, which are detrimental to strength and performance in reduction furnaces. Already during the reduction process the formation of iron bridges can occur between the pellets, which clump forming clusters that compromise the flow of gases inside the furnaces. This problem can be minimized by coating the pellets with a magnesium oxide coating, which inhibits the formation of bridges. Given the importance of characterizing cracks and coating on the surface of the pellets, this dissertation developed methodologies for acquisition, processing and digital analysis of images acquired with a stereoscope. Adjustable sample holders were developed which allowed the acquisition of 2D images of approximately spherical pellets of different sizes, covering most of the surface and avoiding overlapping analysis regions. The crack analysis routine compared two segmentation methods and provided attributes such as mean thickness, area fraction and length. The coating analysis routine used threshold segmentation and measured the fraction of area occupied in each pellet. The use of the sample holders was fundamental to the success of the acquisition procedure. Crack analysis or coating routines were robust for different samples.

Thesis (MBA)--Stellenbosch University, 2007. / ENGLISH ABSTRACT: Human resources budgeting at Sishen mine had been done, for as long as the researcher has been employed at the mine, according to history as well as according to the demands of the financial situation. Consequently, human resources shortages have been corrected by external labour which is often more expensive than internal labour. During the annual budgeting period when top management applies pressure to cut costs, the operations budget is easy to defend. With the help of Excel spreadsheets or maintenance management systems, maintenance managers can present strong arguments for not cutting the operations budget. Budget deficits are then easily corrected by means of negative adjustments to the human resources budget. This research will explore the issue of whether a tool exists to calculate the human resources budget scientifically. A target was set to develop a tool or model for human resources budgeting or to investigate whether such a tool does not already exist. A literature survey was done to determine world best practices regarding the calculation of human resources budgeting. The literature studied guided the researcher to a computerised maintenance management system (CMMS) and it was found that Sishen already has one of the best (SAP) in place. Sishen even has a process (Routine Work Management or RWM) in place which helps to get all maintenance information into SAP to make the necessary information available for effective maintenance. It was further found that SAP, which has been used by the mine for several years, can already provide the human resources requirements for any future period. The RWM process which helps to get information in and out of SAP has been in use for some time already. Unfortunately the process was poorly executed and the information is not reliable. This statement is supported by the internal (Kirstein, 2006) and external (Aurea, 2006) audits done at the mine during 2006. The external audit was done by Aurco (2006). The author concluded that Sishen has a tool but not a strategy to utilise RWM successfully. One of the reasons why RWM was poorly executed was the fact that there is a lack of support from the people in the workplace. These individuals claim that they were not consulted when RWM was introduced at the mine and as a result they did not buy in. A proper change management process was not followed and the employees suspected that RWM was implemented to play policeman or to measure how much spare time they have and reduce the workforce accordingly, as in the case of the Prometheus project. Consequently they admit to manipulating RWM's measured outcomes, ignoring it or deliberately undermining it. They added that RWM is easy to manipulate and perceived it as a farce by many of the participants, A decision was taken to use the Kotter change management process to run a project to get RWM to the required level. Kotter's eight steps for successful large-scale change can be utilised with great success to achieve the required changes. After a brainstorming session and from the recommendations of the two audits a list of ideas was compiled. These ideas should help to get RWM to a level where human resources requirements can be drawn from SAP for any period in the future. Although the research was aimed at getting human resources budgeting from SAP, it will also have other advantages. The ratio between planned and unplanned maintenance will be better because RWM will ensure better maintenance / AFRIKAANSE OPSOMMING: Mannekragbegroting op Sishen-myn is, vir solank die navorser deel is van die myn, gedoen volgens die behoeftes van die verlede asook volgens wat deur die finansiele situasie toegelaat is. Gevolglik het dit dikwels gebeur dat die tekorte aan mannekrag aangevul is met huurarbeid wat dikwels duurder is as eie mannekrag. Tydens die begrotingsrondte kan die geld wat aangevra word vir die instandhouding van die toerusting goed beveg word omdat die instandhoudingspersoneel waterdigte argumente kan aanvoer oor hoe die begroting bereken is. Begrotingstekorte word gevolglik maklik reggestel met negatiewe aanpassings op die mannekragbegroting. Hierdie studie gaan die bestaan ondersoek van 'n gereedskapstuk of model om die mannekragbegroting wetenskaplik te kan bereken. Daar is 'n doelwit gestel om 'n model te ontwikkel vir mannekragberekening of om vas te stel of daar nie reeds iets bestaan nie. 'n Literatuurstudie is gedoen om vas te stel wat wereldwye beste standaarde ten opsigte van mannekragberekening is. Dit het die navorser gelei na gerekenariseerde instandhoudingsbestuurstelsels (CMMS) en daar is bevind dat Sishen reeds een van die beste stelsels gebruik (SAP). Sishen het selfs 'n proses ("Routine Work Management" of RWM) om alle instandhoudingsinligting in SAP te kry sodat die regte inligting weer beskikbaar kan wees vir effektiewe instandhouding. Daar is verder bevind dat SAP, wat reeds vir verskeie jare in gebruik is, enige tydperk in die toekoms se mannekragbehoeftes kan bepaal. Die RWM-proses wat moet help om inligting in en uit SAP te kry, is ook reeds geruime tyd in gebruik, maar ten spyte daarvan word die proses afgewater en is die inligting nie betroubaar nie. Hierdie stelling is bewys deur middel van twee ouditte wat in 2006 op RWM gedoen is. Die een audit was 'n interne audit terwyl die ander deur die maatskappy Aurea gedoen is. Die afleiding kon dus gemaak word dat daar wel 'n gereedskapstuk is, maar dat geen strategie bestaan om dit effektief te gebruik nie. Een van die redes waarom RWM as 'n afgewaterde proses beskryf kan word, is 'n gebrek aan ondersteuning deur die mense in die werksplek. Die mense beweer dat hulle nie geken is ten tye van die bekendstelling van RWM nie en hulle het dus nie ingekoop nie. Die afleiding is gemaak dat daar nie goeie veranderingsbestuur toegepas is toe RWM aan die myn bekendgestel is nie. Die werknemers het vermoed dat RWM ingestel is om hulle te polisieer of te bepaal hoeveel vrye tyd hulle het en die werksmag dienooreenkomstig af te skaal, soos in die geval van die Prometheusprojek. Gevolglik het hulle erken dat hulle die RWM se uitkomste gemanipuleer het, dit geignoreer het, of doelbewus ondermyn het. Hulle het bygevoeg dat RWM maklik gemanipuleer kan word en dat baie dit as 'n klug beskou. Daar is besluit om die Kotter-model te gebruik om 'n projek te loods om RWM op die vereiste standaard te kry. Dit word as die geskikste model beskou om die nodige veranderingsbestuur toe te pas. 'n Lys van idees is opgestel na aanleiding van 'n dinkskrumsessie met die werknemers asook van voorstelle wat in die twee ouditverslae gemaak is. Herdie idees moet RWM in plek kry sodat mannekragbehoeftes vir enige tydperk in die toekoms vanuit SAP verkry kan word. Alhoewel die navorsing daarop gemik was om mannekragbegroting vanuit SAP te bekom, hou dit ook 'n ander voordeel in, naamlik 'n beter verhouding van beplande tot onbeplande instandhouding omdat goeie RWM-prosedures beter instandhouding en gevolglik beter beskikbaarheid gaan verseker.

Thesis (MBA)--Stellenbosch University, 2004. / ENGLISH ABSTRACT: Early in 2001, Thabazimbi Iron Ore mine embarked upon a Leadership and Culture Change strategy. This program was one of the five strategic goals decided upon as part of the strategic drive to improve the performance of the business. A formal, structured implementation plan was crafted in house to approach the initiative. The plan was based on the literature of a number of prominent authors in the fields of leadership, competence theory and change management. The plan is built around a model known as the "Thabazimbi Thumbprint" which is primarily based on the work of Bernard Bass and Bruce Avolio in the field of Transfomational Leadership, and Dr Jay Hall's research and literature on the Competence Process. The primary aims of the implementation of this strategy at the mine were to: • Address the damage done to morale and commitment levels by repeated downsizing and the threat of mine closure. • Establish a high performance team culture. • Remove blockages to performance and the development of human potential. The strategy and implementation plan of the mine is compared against current literature within the fields of leadership and change management and significant similarities are observed. Even though the implementation of this initiative has only been running for some 2 years and is far from complete, a number of significant improvements have been made in terms of collaboration, commitment, trust in management and the reduction of conflict. In addition the performance of the mine in the field of safety and health has vastly improved, the production process is currently stable and targets are met, operating costs have reduced by 4% year on year and the current life of mine has been extended to 10 years. The writer has been the Engineering Manager at the mine from December 2001 and has been responsible for the implementation of this strategy within the Engineering department of the mine. The strategy and implementation plan serves as an example of a fully integrated and comprehensive approach to implementing such an initiative, while remaining simple and practical. The author identifies a number of deficiencies within the strategy used by the mine and makes some recommendations to improve the process that should be considered with respect to the future implementations of this type of initiative. / AFRIKAANSE OPSOMMING: Thabazmbi Ysterertsmyn met 'n Leierskap en Kultuur veranderingstrategie aan die begin van 2001 begin. Die program was deel van vyf strategiese besigheidsdoelwitte wat daarop gemik was om die kern te vorm van die strewe na 'n verbeterde prestasie van die besigheid. 'n Formele, gestruktureerde implementeringsplan is deur die myn ontwikkel vir die daarstelling van die inisiatief. Die plan was op die literatuur van prominente skrywers in die leierskap, bevoegtheidsteorie en veranderingsbestuur rigtings gebaseer. Die plan is gebou op 'n model bekend as die "Thabazimbi Thumbprint" en is gebaseer op die werk van Bernard Bass en Bruce Avolio in die veld van Transformasie Leierskap, en op Dr Jay Hall se navorsing en literatuur oor die "Competence Process". Die primere mikpunte van die implementeering van die strategie op die myn was die volgende: • Om die skade wat herhaalde afskalings en dreigemente van toemaak aan die moraal en toegewydheid van die werksmag gedoen het, aan te spreek. • Om 'n hoe presterende spankultuur te vestig. • Om die blokasies wat onderprestasie veroorsaak en die onderontwikkeling van menslike potensiaal uit die weg te ruim. Die strategie en implementeringsplan is met huidige literatuur in die leierskap- en kultuurveranderingsrigtings vergelyk. Daar is 'n groot mate van ooreenstemming waargeneem. Hoewel hierdie inisiatief maar slegs twee jaar aan die gang is en nog ver van klaar is, is daar al reeds 'n merkwaardige verbetering te bespeur in terme van samewerking, toewyding, die vertroue in bestuur en die vermindering van konflik. Bo en behalwe eersgenoemde pluspunte is daar ook 'n groot verbetering wat betref die gesondheid- en veiligheidsfaktore op die myn. Die produksieproses is stabiel en doelwitte word behaal. Die operasionele kostes is met 4% per jaar besnoei en die huidige lewe van die myn is verleng tot 10 jaar. Die skrywer is die Ingenieursbestuurder van die myn vanal Desember 2001 en was verantwoordelik vir die implementering van die strategie binne die ingenieursafdeling van die myn. Die strategie en implementeringsplan dien as 'n voorbeeld van 'n volledig geintegreerde benadering tot implimentering van so 'n inisiatief, terwyl dit prakties en eenvoudig bly. Die skrywer identifiseer 'n aantal leemtes binne die strategie soos deur die myn gebruik en maak aanbevelings vir die verhetering van die proses wat in die toekoms in ag geneem behoort te word in die implimentering van hierdie tipe inisiatiewe.

Green national accounts are a complement to the more traditional GDP measure which includes natural capital and the depreciation and regeneration of natural capital. The United Nations have developed an international standard model, the System of Environmental-Economic Accounting, for valuing natural resources within the green national accounts. The method is based on forecasts of future streams of expected incomes from the resource. This study aims to find out whether the valuation method used to forecast future incomes from iron ore and timber according to the international standard is consistent with the actual outcomes. In Sweden, previous studies have been made to develop green national accounts from the 1800s onward. By using the United Nations’ current and previous valuation methods and performing calculations on historical resource rents it is possible to evaluate how well the methods can estimate true future values. This study shows that both valuation methods systematically misestimate the future income streams from both resources. / Gröna nationalräkenskaper är ett komplement till det mer traditionella BNP-måttet som även tar hänsyn till bland annat naturkapitalet och dess förslitning. FN har utvecklat en internationell standardmodell för gröna nationalräkenskaper, System of Environmental-Economic Accounting (SEEA), där en rekommenderad värderingsmetod för naturkapital finns angiven. Värderingsmetoden är baserad på framtida, förväntade, inkomstflöden från naturresursen. Den här studiens syfte är att ta reda på om värderingsmetoden för att förutse framtida intäkter för järnmalm och skog enligt den internationella standarden stämmer överens med de faktiska utfallen. I Sverige har tidigare studier gjorts för att utveckla gröna nationalräkenskaper från 1800-talet och framåt. Genom att använda FN:s nuvarande och tidigare rekommenderade värderingsmetoder för naturresurser och göra beräkningar på historiska vinster från naturresursen kan man se hur väl värderingsmetoderna fungerar i praktiken. Den här studien visar att bägge värderingsmetoderna systematiskt felskattar de framtida intäktsflödena från bägge resurser.

The dust particles generated due to mechanical wear of iron ore pellets and clusters formed in molten stainless steel alloyed with rare earth metals (REM) are considered in this study. Firstly, the influence of the characteristics of iron ore pellets, applied load on a pellet bed and partial reduction of the pellets on the size distribution of the generated dust was investigated. Secondly, REM clusters are investigated to evaluate the size distribution of the clusters. Also, an extreme value distribution (EVD) analysis has been applied for the observed REM clusters. The large sized pellets showed 10-20% higher wear rate than small sized pellets during wear in a planetary mill. Moreover, an increase of ~67% was observed in the friction and dust generation in the pellet bed as the applied load increased from 1 to 3 kg. Also, it was observed that a higher friction in the pellet bed can lead to an increased amount of airborne particles. The mechanical wear experiments of pellets reduced at 500 °C (P500) and 850 °C (P850) showed that P500 pellets exhibit ~16-35% higher wear rate than unreduced pellets. For the P850 pellets, the wear is inhibited by formation of a metallic layer at the outer surface of the pellets. The mechanism of dust generation has been explained using the obtained results. A reliable cluster size distribution of REM clusters was obtained by improving the observation method and it was used to explicate the formation and growth mechanism of REM clusters. The results show that the growth of clusters is governed by different types of collisions depending on the size of the clusters. For EVD analysis three different size parameters were considered. Moreover, using the maximum length of clusters results in a better correlation of EVD regression lines compared to other size parameters. Moreover, a comparison of predicted and observed maximum lengths of clusters showed that further work is required for the application of EVD analyses for REM clusters. / Studien fokuserar på två olika typer av mikropartiklar som är valda från olika delar av järn- och ståltillverkningsprocessen. Dessa partiklar är dels stoft som genereras på grund av mekanisk nötning av partiklar och dels klusters som bildas i flytande rostfria stål legerade med sällsynta jordartsmetaller (REM). Inledningsvis så undersöktes inverkan av tre faktorer på storleksfördelningen hos stoft som bildas vid hantering av järnoxidpellets. De undersökta faktorerna inkluderade karakteristiken hos järnoxidpellets, det applicerade trycket på pelletsbädden och den partiella reduktionen av järnoxidpellets. Därefter så utfördes tredimensionella undersökningar av REM kluster som extraherats med hjälp av elektrolytisk extraction för att bestämma storleksfördelningen hos klustren. Dessutom så utfördes en extremvärdesdistribution (EVD) studie för de studerade klustren. En planetkvarn användes för att undersöka inverkan of karakeristiken hos pellets på stoftbildningen. Resultaten visade att storleken på pellets kan påverka nötningshastigheten under dessa försöksförhållanden. Pellets som hade en större storlek (13.5&lt; Deq &lt;15.0 mm) uppvisade en 10 till 20% högre nötningshastighet i jämförelse med mindre pellets (9.5&lt; Deq &lt;12.5 mm). Baserat på analyserna av stoftet som genererades under nötningsexperimenten så konstaterades att nötningsmekanismerna för dessa pellets var abrasions- och kollisionsnötning. En pelletsbädd skapades för att möjliggöra studier av inverkan av ett applicerat tryck på stoftbildningen och friktionskrafterna i en pelletsbädd. Ett varierat tryck på mellan 1 till 3 kg applicerades på pelletsbädden. Resultaten visade att en ökning på ~67% av friktionskraften och stoftbildningen ägde rum när det applicerade trycket ökades från 1 till 3kg. Dessutom så visade resultaten att en högre friktionskraft i pelletsbädden kan resultera in en ökad mängd luftburna partiklar. Den mekaniska nötningen av pellets som reducerats vid 500 °C (P500) och 850 °C (P850) studerades också genom användande av en planetkvarn. Resultaten visade att P500 pellets uppvisade en ~ 16 till 35% högre nötningshastighet i jämförelse med oreducerade referenspellets.  Resultaten för P850 pellets visade att den mekaniska nötningen motverkades genom bildningen av ett metalliskt skikt på den yttre delen av pelletsen. Resultaten visade också att stoftet som bildats pga mekanisk nötning av reducerade pellets innehöll 3 till 6 gånger mer grova partiklar  (&gt;20µm) i jämförelse med stoft som bildats från oreducerade pellets. Slutligen så diskuterades hur dessa resultat kan relateras till industriella förhållanden med avseende på mekanismerna som är involverade i den mekaniska nötningen av pellets samt med avseende på relationen mellan hastigheten av de utgående gaserna och storlken och morfologin hos stoftpartiklarna. Klusters innehållande REM-oxider som extraherats från en 253MA rostfri stålsort undersöktes med användande av en tredimensionell teknik. En trovärdig storleksfördelning av klusters (CSD) erhölls genom att förbättra undersökningsmetoden och denna användes för att studera bildningen och tillväxten av REM oxider. Dessutom så användes cirkularitetsfaktorn hos klusters för att dela in klustren i två olika grupper, vilka bildas och tillväxer enligt olika mekanismer. Resultaten visade också att tillväxten av klusters gynnas av olika typer av kollisioner som beror av av storleken på klusters. För REM-klusters så drogs slutsatsen att turbulenta kollisioner är den huvudsakliga mekanismen som påverkar tillväxten. Avhandlingen behandlar även problemet om hur det är möjligt att hantera synfält där det inte förekommer kluster vid en extremvärdesdistribution (EVD) analys. Tre olika parametrar undersöktes i EVD analysen. Resultaten visar att om den maximala längden på kluster (LC) används i analysen så erhålls den bästa korrelationen gällande regressionslinjen för en EVD analys. Specifikt så var R2 värdet upp till 0.9876 i jämförelse med de andra storleksparametrarna som har värden i intervallet 0.9656 – 0.9774. Slutligen så visar resultaten från en jämförelse mellan beräknade och observerade maximala klusterlängder att EVD analyser för studier av REM kluster behöver undersökas ytterligare i framtiden. / <p>QC 20161128</p>

Cherchant des voies de réduction drastique des émissions de CO2 d’origine sidérurgique (projet européen ULCOS), nous avons envisagé une réduction du minerai de fer par l’hydrogène pur dans un réacteur du type four à cuve. L’approche suivie a associé bibliographie, expérimentation et modélisation. Le déroulement de la réaction chimique et sa cinétique ont été analysés à partir d’expériences thermogravimétriques et de caractérisations physico-chimiques d’échantillons en cours de réduction. Un modèle cinétique spécifique a été mis au point, qui simule les réactions successives, les différentes étapes du transport de matière et le frittage éventuel du fer, à l’échelle d’une particule de solide. Enfin, un modèle numérique bidimensionnel du four à cuve a été écrit. Il décrit l’évolution des températures et des compositions des solides et des gaz en tous points d’un réacteur fonctionnant sous hydrogène. Une des originalités de ce modèle est l’utilisation de la loi des temps caractéristiques additifs pour exprimer les vitesses des réactions. Celle-ci permet de coupler les deux échelles que sont celles des particules et du réacteur, tout en gardant des temps de calculs raisonnables. A partir des simulations réalisées, l’influence des paramètres du procédé a été quantifiée. Des conditions opératoires optimales ont été dégagées, qui illustrent bien le potentiel du procédé / In an effort to find new ways to drastically reduce the CO2 emissions from the steel industry (ULCOS project), the reduction of iron ore by pure hydrogen in a shaft furnace was investigated. The work consisted of literature, experimental, and modelling studies. The chemical reaction and its kinetics were analysed on the basis of thermogravimetric experiments and physicochemical characterisations of partially reduced samples. A specific kinetic model was designed, which simulates the successive reactions, the different steps of mass transport, and possible iron sintering, at the particle scale. Finally, a 2-dimensional numerical model of a shaft furnace was developed. It depicts the variation of the solid and gas temperatures and compositions throughout the reactor. One original feature of the model is using the law of additive characteristic times for calculating the reaction rates. This allowed us to handle both the particle and the reactor scale, while keeping reasonable calculation time. From the simulation results, the influence of the process parameters was assessed. Optimal operating conditions were concluded, which reveal the efficiency of the hydrogen process

[pt] O ferro é extraído sob a forma de minério de ferro, sendo 99 por cento utilizado na indústria siderúrgica. Os documentos normativos existentes indicam a volumetria como à técnica analítica para quantificar o teor de ferro em minério de ferro, com exceção da ISO 9516-1: 2003, que, recomenda a espectrometria de fluorescência de raios-X por comprimento de onda (WDXRF). Na literatura são descritos estudos utilizando a espectrometria de fluorescência de raios-X por dispersão de energia (EDXRF) para quantificar ferro em minério de ferro, mas em nenhuma destas publicações é caracterizada a confiabilidade metrológica e a incerteza de medição, sendo outros aspectos importantes na seleção de um método analítico o impacto económico e tempo de análise. No presente trabalho realizou-se um estudo comparativo de impacto económico, tempo de análise e desempenho metrológico na quantificação de ferro em minério de ferro por meio da técnica de EDXRF, comparando-o com a espectrofotometria de absorção molecular e volumetria (titulação com dicromato de potássio), abrangendo a incerteza de medição e a avaliação de parâmetros de validação para EDXRF. A análise volumétrica foi realizado baseado nas normas ANBT NBR 8577:2011 e ASTM E246:2010. Na espectrofotometria de absorção molecular, adaptou-se o método da ortofenantrolina descrito na norma ABNT NBR 13934:1997. Nas outras técnicas precisam-se da abertura da amostra, na EDXRF, as amostras foram preparadas na forma de pastilha (pó de minério prensado). Os métodos avaliados apresentaram desempenhos metrológicos equivalentes, os melhores indicadores de custo e tempo em longo prazo foram observados para o método por EDXRF na quantificação do teor de ferro em minério. / [en] After its extraction in the form of iron ore, 99 per cent of the iron is employed in the steel industry. The normative documents existents recommend to volumetry as the technical analytic for quantification of iron in iron ore, with the exception of ISO 9516-1: 2003, which recommends the fluorescence spectrometry X-ray wavelength (WDXRF). In literature, there are studies using energy dispersive Xray fluorescence spectrometry (EDXRF) to quantify iron in iron ore, but none of these is characterized by complete validation and measurement uncertainty. Other aspects to be considered when selecting an analytical method are the financial cost and the time for analysis. In this work it is carried out a comparative study of financial cost, time analysis and metrological performance on quantification of iron ore through the EDXRF technique, in comparison with the results obtained by molecular absorption spectrophotometry and volumetry (titration with potassium dichromate), including measurement uncertainty evaluation and some parameter of validation for EDXRF. The molecular absorption spectrophotometry measurements were performed by colorimetric orthophenanthroline method. Unlike the other approaches that require sample preparation with acid, for EDXRF measurements, samples were prepared in tablet form (pressed iron ore powder). The evaluated methods presented equivalent metrological performances on determining iron in ore, but the best long-term outcome for cost was observed in the results obtained by EDXRF method.

[pt] O presente estudo aborda o planejamento operacional de lavra de minério de ferro com alocação dinâmica de caminhões, em um complexo de minas, no Estado do Pará. O objetivo é balancear as taxas de utilização dos recursos logísticos utilizados em operações de extração e transporte de minério de ferro, considerando aumento ou diminuição em suas unidades de uso. Inicialmente, é feita uma revisão da literatura que apresenta como a logística e seus componentes de desempenho se associam a produção de minério de ferro no estado, identificando as principais incertezas dos processos logísticos considerados, além de apresentar o problema operacional de lavra com alocação dinâmica de caminhões e técnicas de simulação e de otimização individualmente, ressaltando seu melhor desempenho em conjunto. Esta revisão respalda a fase de aplicação da Simulação-Otimização, que ocorre em um sistema dinâmico, estocástico e de eventos discretos. A análise consistiu no diagnóstico do sistema produtivo, avaliação dos relacionamentos entre os processos envolvidos, construção de um modelo de simulação a partir dos dados coletados e otimização, verificando-se seus outputs como origem dos cenários a serem propostos na nova simulação, para avaliar as potenciais modificações na utilização dos recursos. A Simulação- Otimização foi executada utilizando-se o pacote de simulação ProModel, que inclui um software de Otimização baseado em Algoritmos Genéticos, o SimRunner. Como resultado, o modelo de Simulação-Otimização foi construído para apoiar decisões estratégicas e operacionais da empresa em estudo, apresentando resultados satisfatórios para o balanceamento das taxas de utilização dos recursos logísticos envolvidos na operação. / [en] The present study highlights the operational mining planning of iron ore with dynamic allocation of trucks in a mining complex in the State of Pará. The goal is to balance the utilization rates of logistical resources used in mining operations and transportation of iron ore, considering the increase or decrease of the number of resources in use. Initially, a literature review presents how the logistics and its performance components are associated with the iron ore production in the State of Pará, identifying uncertainties on key logistics processes, also presenting the operational mining planning with dynamic allocation of trucks and techniques of simulation and optimization individually, highlighting the best setting when considered together. This review endorses the implementation of the Simulation-Optimization phase, which occurs in a dynamic, stochastic and discrete events system. The analysis consisted in the diagnosis of the production system, the evaluation of the relationships between the logistics processes involved, the construction of a simulation model based on the collected data and optimization, verifying their outputs as the source for the scenarios to be proposed in the new simulation to evaluate the potential changes in resource utilization. The Simulation-Optimization was performed using the ProModel simulation package, which includes an optimization software based on Genetic Algorithms, the SimRunner. As a result, the Simulation-Optimization model was built to support strategic and operational decisions of the studied company, presenting satisfactory results to balance the utilization rates of all logistical resources involved in the operation.

[pt] O minério de ferro é um material policristalino oriundo de processos naturais complexos durante tempos geológicos, que dão origem a características intrínsecas e comportamento industrial variado. A grande maioria dos minérios de ferro brasileiro é essencialmente hematítico. A hematita pode ser classificada como lobular, lamelar, granular, microcristalina ou martita. Na industria mineral, esta caracterização é tradicionalmente realizada por operadores humanos a partir de observação de amostras de microscópio ótico, sujeita a grandes variações. Assim, é relevante desenvolver um procedimento que permita a discriminação dos diferentes tipos de hematita e a medida de características tais como o tamanho do cristal. Esta tese propõe um sistema que mede e classifica automaticamente tipos texturais de hematita baseado no processamento e na análise de imagens de microscopia ótica, em campo claro, polarização linear e polarização circular. Foram desenvolvidos rotinas para aquisição, registro,, segmentação, reconhecimento e análise morfológica de cristais hematita. A segmentação automática de cristais de hematita foi baseada no calculo da distância espectral, a fim de controlar o crescimento de regiões partindo das sementes. Os resultados da identificação dos cristais obtidos, tanto nas imagens obtidas com polarização linear quanto com polarização circular, foram muito promissores. Atributos de tamanho e forma dos cristais identificados foram obtidos. Estes dados foram usados como conjunto de treinamento para classificadores supervisionados, permitindo reconhecer as classes de hematita granular, lamelar e lobular. Taxas de acertos globais próximas a 98 por cento forma obtidas, tanto para autovalidação, quanto para avaliação cruzada. / [en] Iron ore is a polycrytalline material created by complex natural process during geological period, wich give rise to intrinsic characteristics and varied industrial behavior. The vast majority of the Brazilian iron ores belong essentially to the hematitic type. Hematite can be classified as lobular, lamelar, granular micro-crystalline or martite. In the mineral industry, the characterion of iron ore and its agglomerates is traditionally developed by human operatorsform the observation of samples under the optical microscop, wich may suffer large variations. Thus, it is important to develop a procedure that allows the discrimation of the different hematite types and the measurement of characteristics suchs crystal size. The present thesis proposes a system for the automatic classification of hematite textural types, based of digital on processing and analysis of optical microscopy images, in bright field, linear and circular polarized light. Routines were developed for the acquisition, registration, recognition and morphological analysis of hematite crytals. The automatic segmentation of hematite crystals was based on calculating the spectral distance, in order to control the region expansion form the seeds. The results regarding the identification of the obtained cystals were very promising. Size and shape attributes were obtained and used as a training set for supervised classifiers, leading to the recognition of granular, lamelar and lobular hematite classes. Global sucess rates close to 98 percent were obtained concerning self-validation as well crossed validation.