Evaluation of Scale-up Model for Flotation with Kristineberg Ore Adam Isaksson Chemical Engineering, master's level 2018 Luleå University of Technology Department of Civil, Environmental and Natural Resources Engineering Evaluation of Scale-up Model for Flotation with Kristineberg Ore Adam Isaksson 2018 For degree of MASTER OF SCIENCE Luleå University of Technology Department of Civil, Environmental and Natural Resources Engineering Division of Minerals and Metallurgical Engineering Printed by Luleå University of Technology, Graphic Production 2018 Luleå 2018 www.ltu.se Preface As you may have figured out by now, this thesis is all about mineral processing and the extraction of metals. It was written as part of my studies at Luleå University of Technology, for a master’s degree in Chemical Engineering with specialisation Mineral and Metal Winning. There are many people I would like to thank for helping me out during all these years. First of all, my thanks go to supervisors Bertil Pålsson and Lisa Malm for the guidance in this project. Iris Wunderlich had a paramount role during sampling and has kindly delivered me data to this report, which would not have been finished without her support. I would also like to thank Boliden Mineral AB as a company. Partly for giving me the chance to write this thesis in the first place, but also for supporting us students during our years at LTU. Speaking of which, thanks to Olle Bertilsson for reading the report and giving me feedback. The people at the TMP laboratory deserves another mention. I am also very grateful for the financial support and generous scholarships from Jernkontoret these five years. At last, but certainly not least, I would like to thank my family for always supporting me in my decisions. I have got the chance to express my inherent curiosity, for which I am truly grateful. This thesis was written in memory of my grandmother, who was one of my greatest supporters. It is said that the strongest metals are forged in the greatest of stellar hearts. Even the brightest of stars will one day set, but their warmth echoes through the vastness of eternity. I am now beginning a new phase of my life, for whatever it may hold. With a different sense of purpose, I am entering a realm of the unknown. Adam Isaksson Boliden, May 2018 iii Abstract The objectives of this project were to survey the flotation circuit of the Boli- den concentrator, mass balance collected data and evaluate a scale-up model for laboratory flotation results. The model assumes that half of the recovery to cleaner middlings in a standard laboratory test would report to the final concentrate if it were done in closed circuit, as is the case in a full-scale plant. It has been used by Boliden Mineral AB since 1982 but its accuracy had not been studied since 1986. The model can be categorised as of open circuit type with scale-up factors. The project was based on a complex Ag-Au-Cu-Pb-Zn sulphide ore from the Kristineberg mine. Laboratory tests were done to produce concentrates of CuPb, Cu, Pb and Zn with pulp samples from the concentrator as feed material. The software HSC 9.3 was used to mass balance data from the plant survey. It was decided that the model would be deemed usable if it was able to predict the plant results with the same accuracy as in the survey of 1986. A simulated locked cycle test with split factors (Agar & Kipkie, 1978) was identified as an alternative scale-up model. The results showed that the model was able to predict the plant results with the same accuracy as in 1986. It was especially good at predicting grade and recovery of the main element in a concentrate. For example, it predicted an 18 % higher grade and 11 % lower recovery of Cu to the CuPb concentrate, while a 3 % lower grade and 11 % lower recovery of Zn was predicted to the Zn concentrate. The locked cycle model gave much worse predictions on grades, but more accurate recoveries. It was also better at predicting the behaviour of minor impurity elements such as As and Bi. A recommendation is to combine the two alternatives in a type of “mixed cycle” model. In this study, it would have predicted an 18 % higher grade and 7 % lower recovery of Cu to the CuPb concentrate, as well as a 3 % lower grade and 1 % higher recovery of Zn to the Zn concentrate compared with plant results. Such a model seems to give better figures, but should be put to the test on more samples and ores to confirm this belief. It could at the very least be used to check the reliability of results predicted by the current scale-up model. Keywords: flotation, HSC, Kristineberg, locked cycle, mass balancing, mixed cycle, open circuit, scale-up iv Sammanfattning (SWE) Syftet med det här examensarbetet var att utföra en detaljprovtagning av flotationskretsen i Bolidens anrikningsverk, massbalansera data och sedan utvärdera en modell för uppskalning av resultat från laboratorieflotationer. Modellen antar att hälften av utbytet till returgodset i ett satsvis laborato- rieförsök skulle rapportera till det slutliga koncentratet om det återcirkuler- ades, såsom i ett anrikningsverk. Den har använts av Boliden Mineral AB sedan 1982 men utvärderades senast 1986. Kategoriskt kan den ses som en uppskalningsmodell av typen öppen krets med skalfaktorer. Projektet baserades på en komplex Ag-Au-Cu-Pb-Zn sulfidmalm från gru- van i Kristineberg. Laboratorieförsök utfördes för att ta fram koncentrat av CuPb, Cu, Pb och Zn, med pulpprover från driften som utgångsmaterial. Programmet HSC 9.3 användes för att massbalansera datan från provtagnin- gen. Det bestämdes att modellen skulle anses som godtagbar ifall den kunde förutspå driftresultatet med samma noggrannhet som 1986. Ett simulerat försök av typen sluten krets (Agar & Kipkie, 1978) identifierades som den mest intressanta alternativmodellen och även den utvärderades. Resultaten visade att modellen än idag ger godtagbara förutsägelser med samma noggrannhet som 1986. Modellen var särskilt bra på att förutspå halt och utbyte av den huvudsakliga metallen till dess eget koncentrat. Den förutspådde exempelvis en 18 % högre halt och 11 % lägre utbyte av Cu till CuPb-koncentratet, samt 3 % lägre halt och 11 % lägre utbyte av Zn till Zn-koncentratet. Den alternativa modellen gav sämre förutsägelser med avseende på halter, men bättre med avseende på utbyten. Den var bättre på att förutspå beteendet hos låghaltiga föroreningar såsom As och Bi. Rekommendationen är att kombinera de två modellerna till en “bland- kretsmodell”. I den här undersökningen hade ett sådant alternativ förutspått en 18 % högre halt och 7 % lägre utbyte av Cu till CuPb-koncentratet, samt 3 % lägre halt och 1 % högre utbyte av Zn till Zn-koncentratet jämfört med driftresultatet. En sådan modell tycks ge bättre förutsägelser, men bör tes- tas på fler prover och malmtyper. Den borde åtminstone kunna användas för att kontrollera trovärdigheten hos resultaten förutspådda av den nuvarande modellen. Nyckelord: blandkrets, flotation, HSC, Kristineberg, sluten krets, massbal- ansering, öppen krets, uppskalning v Examination objectives The author’s contribution to this work and requirements for the degree of Master of Science in Engineering according to the Swedish Higher Education Ordinance. Higher Education Ordinance Motivation §1 Demonstrated knowledge of the disci- Chapters 1 and 2. Presentation of plinary foundation of and best practice published flotation scale-up methods in his or her chosen field of technology and the Boliden practise. as well as insight into current research and development work. §2 Demonstrated both broad knowledge of Chapters 1, 2 and 3. Flotation the- his or her chosen field of technol- ory and circuit design. Mathematical ogy, including knowledge of mathemat- knowledge required for mass balanc- ics and the natural sciences, as well ing and flotation kinetics. Specialised as a considerable degree of specialised knowledge in mass balancing of flota- knowledge in certain areas of the field. tion circuits and flotation test work. §3 Demonstrated the ability to identify, Chapters 3 and 4. Planning of flota- formulate and deal with complex issues tion test work and sampling of the con- autonomously and critically and with centrator. Mass balancing with HSC a holistic approach and also to partici- software. Developed an alternative pate in research and development work scale-up procedure. and so contribute to the formation of knowledge. §4 Demonstrated the ability to create, Chapters 2, 3 and 4. Identification of analyse and critically evaluate various scale-up models in literature and plan- technological solutions. ning of test work to evaluate said mod- els. Developed an alternative scale-up procedure. §5 Demonstrated the ability to plan and Chapter 3. Considerations in the mass use appropriate methods to undertake balance such as flow rate estimations advanced tasks within predetermined and which elements to assay. Which parameters. flows to sample and tests to do. vi EXAMINATION OBJECTIVES vii Higher Education Ordinance Motivation §6 Demonstrated the ability to integrate Chapters 3 and 4. Only relatively sim- knowledge critically and systematically ple models were considered or devel- as well as the ability to model, simu- oped since a standard flotation test late, predict and evaluate sequences of generally gives a limited amount of in- events even with limited information. formation. §7 Demonstrated the ability to develop Chapter 4. An alternative scale-up and design products, processes and model was developed. Brief discussion systems while taking into account the of the importance of mineral process- circumstances and needs of individuals ing and sustainability in chapter 1 but and the targets for economically, so- generally not applicable for this thesis. cially and ecologically sustainable de- velopment set by the community. §8 Demonstrated the capacity for team- Sampling was done together with oth- work and collaboration with various ers and required teamwork.