February 2015

CIM Journal & CIM Metallurgical Quarterly

Excerpts taken from abstracts in CIM Journal, Vol. 6, No. 1.
To subscribe, to submit a paper or to be a peer reviewer—www.cim.org

Time-temperature-transformation (TTT) diagram of caustic calcined magnesia

K. Ebrahimi-Nasrabadi, Department of Geology, Faculty of Sciences, Ferdowsi University of Mashhad, Mashhad, Iran; M. Barati, Department of Materials Science and Engineering, University of Toronto, Toronto, Ontario, Canada; and P. W. Scott, Camborne School of Mines, University of Exeter, Penryn, Cornwall, United Kingdom

ABSTRACT The conversion of cryptocrystalline magnesite to caustic magnesia was studied experimentally at temperatures of 400–1,200°C and for calcination times of up to 8 h. A differential thermal analysis–thermal gravimetric analysis showed that decomposition begins at temperatures as low as 340°C and is completed at 600°C. Specific surface area, iodine adsorption number, crystallite size, and loss on ignition were measured to characterize the product quality. It was found that high-quality caustic calcined magnesia can be produced in a narrow temperature (600–650°C) and time range (1–4 h).


 

Effect of low-intensity magnetic fields on constructed wetland mesocosms treating chromium wastewater

A. Rodriguez-Prado, Independent Consultant, Saskatoon, Saskatchewan, Canada

ABSTRACT Magnetic fields affect the growth of cultured cells and plants; however, limited information exists about their effects on vegetation performing environmental remediation. Constructed wetland mesocosms treating hexavalent chromium (Cr(VI)) wastewater exposed to low-intensity magnetic fields (60 Hz, 56.5 × 10−6 Tesla) produced 100% more biomass than the unexposed control. Nonetheless, they removed only 43 ± 27% of Cr(VI), compared to 60 ± 21% for the control. A Cr(VI) reduction expression was developed as a function of the magnetic field. The design and operation of constructed wetlands to treat mining wastewater can be corrected for magnetic field effects.


 

Introduction to the stirred milling of nickel laterites for upgrading nickel

L. Tong and B. Klein, Norman B. Keevil Institute of Mining Engineering, University of British Columbia, Vancouver, British Columbia, Canada; M. Zanin, W. Skinner, K. Quast, and J. Addai-Mensah, Ian Wark Research Institute, University of South Australia, Mawson Lakes, Adelaide, South Australia, Australia; and D. Robinson, Minerals Down Under National Research Flagship, CSIRO Process Science and Engineering, Waterford, Western Australia, Australia

ABSTRACT The stirred milling of nickel laterites offers possibilities for improving liberation and selective size reduction of soft nickel-bearing minerals in laterites. Batch grinding tests were performed in a Netzsch™ LME4 stirred mill on siliceous goethitic, goethitic, and saprolitic nickel laterites. Tests on the −2,000 μm sample displayed the effects of selective comminution. The −38 μm product of grinding the −2,000/+38 μm feed confirmed the effects of selective grinding and nickel upgrading. Size classification followed by stirred milling is recommended for nickel upgrading. The energy requirement in the stirred milling was also investigated.


 

Escalating social risk around mining: Why does it matter and what can be done?

M. D. Evans, Office of the Extractive Sector Corporate Social Responsibility Counsellor, Government of Canada, Toronto, Ontario, Canada

ABSTRACT The mining industry has a significant opportunity to capitalize on past learnings to build better social relationships. The industry’s relationship with society is critical and under pressure. Rising levels of public opposition and social conflict are already having material impacts on operations around the world. The industry has an opportunity to shape the future direction of this social engagement, build public trust, and proactively respond to a material risk to operations, but first it needs to better understand the nature of the challenges and the urgency of addressing them.


Canadian Metallurgical Quarterly cover
Excerpts taken from abstracts in CMQ, Vol. 52, No. 4.
To subscribe – 
www.cmq-online.ca

Wear resistance of coke-crushing hammers

F. Zupanic, University of Maribor, Faculty of Mechanical Engineering, Smetanova ulica, Maribor, Slovenia

ABSTRACT This work investigated several methods for improving the wear resistance of the 42CrMo4 tool steel used for coke-crushing hammers. The methods embraced heat treatment for obtaining different combinations of strength and ductility of the bulk steel, and surface-engineering processes comprising TiN thin-film deposition using magnetron-sputtering, nitriding and WC/Ni weld deposit surfaced by gas metal arc (GMA) method. The wear-resistance was tested under industrial conditions. Oil quenching and tempering significantly increased the wear resistance in comparison to the as-received condition. Conversely, nitriding and TiN-hard coating did not show any significant improvement. WC/Ni weld deposit provided the best protection against wear, which was caused predominantly by hard abrasive particles present in the coke.


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