Influence of geometric design variables on the efficiency of the high energy horizontal chromite type ball milling process

Fatih Dökme; Onur Güven; Mustafa Kemal Kulekci; Ugur Esme; Seref Ocalir

doi:10.3139/120.111058

Article

Influence of geometric design variables on the efficiency of the high energy horizontal chromite type ball milling process

Fatih Dökme , Onur Güven , Mustafa Kemal Kulekci , Ugur Esme and Seref Ocalir

Published/Copyright: July 10, 2017

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From the journal Materials Testing Volume 59 Issue 7-8

Abstract

Elemental chromium (Cr) does not occur in nature, but Cr exists in chromite ores as FeOCr₂O₃. There are some processes to obtain Cr from chromite. For all processes milling process is essential. In milling process of chromite, ball mills are generally used, because follow-up processes need fine particle size. Due to the fact that chromites with a high iron content are hard, mill components like liner and grinding media wear faster than many mines which is a significant problem in chromite grinding. This paper presents an experimental investigation of the influence of liner profile design and speed on chromite ball milling process. For evaluation of the experiments, power consumption, particle size and wear rate datas are calculated. In this experimental study, five liner profiles were designed and worked with three speeds (60, 70 and 80 % critical speed). By this combination, this study contains fifteen experiments. The ball milling process efficiency is related with shape of grinding media, kind of grinding media and product filling degree, ball size distrubition, etc., all other factors are kept constant. It was investigated the effects of liner profiles-milling speed variations on milling efficiency. 70 % critical speed was the optimum speed for all liner types. Best particle size result was meausured in the 10^th experiment as 95 μm which has the highest liner. Also, the steepest liner profile has the second-best result at a critical speed of 70 %. Energy saving is important for selecting liner profile. Besides, shallowest design with 80 % critical speed has the worst particle size result. Although highest liner profile Type 5 has the best result for particle size, the difference of wear rates is nearly two times (160 g versus 90 g) compared to Type 3 which has a particle size result of 100 μm. This means nearly half life time difference between two liners. By considering three parameters, power consumption, particle size and wear rate, the best results occurred with the steepest and medium liner profile, and these may even be further improved.

Kurzfassung

Elementares Chrom (Cr) kommt in der Natur nicht vor, es existiert nur in Verbindungen, z. B. als chromithaltige Erze wie FeOCr₂O₃. Es gibt einige Prozesse, um Chrom aus Chromiten zu erhalten, wobei für alle Gewinnungsmethoden ein wichtiger Prozessschritt das Mahlen ist. Im Mahlprozess des Chromits werden üblicherweise Kugelmühlen verwendet, da die nachfolgenden Prozesse sehr feine Partikel erfordern. Da hocheisenhaltige Chromite hart sind, verschleißen die Mühlenkomponenten und die Mahlkörper schneller als viele andere, was eine besondere Schwierigkeit beim Chromitschleifen darstellt. Im vorliegenden Beitrag wird eine experimentelle Untersuchung der Effekte des Linerprofildesigns und der Geschwindigkeit auf den Chromit-Kugelmahlprozess vorgestellt. Zur Evaluation der Experimente wurden die Daten des Energieverbrauches, der Partikelgröße und der Verschleißrate berechnet. In der experimentellen Studie wurden fünf Linerprofile entworfen und mit drei Geschwindigkeiten (60, 70 und 80 % der kritischen Geschwindigkeit) bearbeitet. In dieser Kombinationsstudie waren fünfzehn Experimente enthalten. Die Effizienz des Kugelmahlprozeseses wurde auch in Bezug zur Medienform, den Medien und dem Produktbefüllungsgrad, der Kugelgrößenverteilung, usw. gesetzt, wobei in dieser Studie alle anderen Faktoren konstant gehalten wurden. Außerdem wurden die Effekte der Linerprofil-Mahlgeschwindigkeits-Variationen auf die Mahleffizienz untersucht. 70 % der kritischen Geschwindigkeit war die optimale Geschwindigkeit für alle Linertypen. Die beste Partikelgröße wurde im zehnten Experiment mit 95 μm gemessen, in dem das höchste Linerprofil verwendet wurde. Außerdem ergab sich mit dem steilsten Linerprofil das zweitbeste Ergebnis bei 70 % der kritischen Geschwindigkeit. Aufgrund der Energieersparnis ist dieser Fall bedeutend für die Wahl des Linerprofils. Die flachste Auslegung mit 80 % der kritischen Geschwindigkeit ergab das schlechteste Resultat. Obwohl sich das Linerprofil Typ 5 hinsichlich der Partikelgröße als am besten erwies, ergaben sich fast zweifach höhrere Verschleißwerte (160 g gegenüber 90 g), im Vergleich zu dem nächsten Ergebnis für Typ 3, in dem sich eine Partikelgröße von 100 μm einstellte. Dies bedeutet eine Differenz für die Linertypen von nahezu der Hälfte. Unter Berücksichtigung der drei Parameter, Energieverbrauch, Partikelgröße und Verschleißrate, wurden die besten Resultate für das steilste und das mittlere Linerprofil erhalten, die zudem verbessert werden könnten.

*Correspondence Address, Associate Prof. Dr. Ugur Esme, Technology Faculty, Mersin University, 33400 Tarsus-Mersin, Turkey, E-mail: uguresme@gmail.com

Fatih Dökme is working as a mechanical engineer at Sisecam Chemicals Group, Soda Sanayii A. S. in Mersin, Turkey. He received his BSc and MSc from the Department of Mechanical Engineering, University of Mersin, Turkey. His research interests include engineering design, welding technology and machinability of materials.

Dr. Onur Güven is a lecturer in the Department of Mechanical Engineering at Mersin University, Turkey. He received his MSc and PhD from the Department of Mechanical Engineering, University of Cukurova, Turkey. His work at the university involves giving courses and conducting research in the areas of welding, surface grinding, modeling, metal cutting and CAD/CAM process. He is the author of numerous international publications on these subjects.

Prof. Dr. Mustafa Kemal Kulekci is Professor in the Department of Mechanical Education, Faculty of Tarsus Technical Education, Mersin University, Turkey. He obtained his PhD degree from Gazi University, Ankara, Turkey in 2000. His research interests include CAD/CAM, friction stir welding, machinability of materials and water jet cutting applications.

Assoc. Prof. Dr. Ugur Esme is working in the Tarsus Technical Education Faculty, Mersin University, Turkey. He obtained his PhD degree from the, Department of Mechanical Engineering, Cukurova University, Turkey, in 2006. His research areas include CAD/CAM technology, welding, modeling, designing and water jet cutting applications.

Seref Ocalir, born in 1982, works as a research assistant at Mersin University Graduate School of Natural and Applied Sciences, Turkey. He obtained his BSc degree and MSc degree from Mersin University, in 2006 and 2009, respectively. His research interests include friction stir welding, machinability of materials, design and corrosion.

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Published Online: 2017-07-10

Published in Print: 2017-07-14

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https://doi.org/10.3139/120.111058