Investigation of the effect of mineralogy as rate-limiting factors in large particle leaching

Abstract Although heap leaching is by now well established in the mining industry, the process remains limited by low recoveries with different rate-limiting factors that are not clearly understood. In this study, three large particle size classes (+19/−25, +9.5/−16, +4.75/−5 mm) were prepared from a sphalerite ore by two different methods of comminution (HPGR and cone crusher). The particles were then packed into leach reactors that were operated continuously for 11 months with well-mixed internal circulation of the leach solution. Characterization of the residue of the leach reactors indicated that there are areas within the ore particles where although sphalerite grains are accessible to the solution, they remain unreacted. X-ray tomography and QEMSCAN® analysis of the selected samples before, during and after leaching, showed increased leaching of sphalerite grains associated with pyrite due to galvanic interactions. Mineral chemistry (Fe, Mn content of sphalerite) and jarosite precipitation were also investigated as factors influencing sphalerite leaching.

[1]  F. Viljoen,et al.  A detailed mineralogical assessment of sphalerites from the Gamsberg zinc deposit, South Africa: The manganese conundrum , 2011 .

[2]  P. Bethke,et al.  Chalcopyrite disease in sphalerite : pathology and epidemiology , 1987 .

[3]  I. González,et al.  Galvanic interactions between galena–sphalerite and their reactivity , 2007 .

[4]  I. V. Mitchell,et al.  Surface structure of sphalerite studied by medium energy ion scattering and XPS , 2007 .

[5]  Yuqiong Li,et al.  Effect of vacancy defects on electronic properties and activation of sphalerite (110) surface by first-principles , 2010 .

[6]  Edelmira D. Gálvez,et al.  An analytical model approach to heap leaching , 2009 .

[7]  S. Banwart,et al.  Experimental study of acidity-consuming processes in mining waste rock: some influences of mineralogy and particle size , 1999 .

[8]  Francesca Pagnanelli,et al.  Shrinking core model with variable activation energy: A kinetic model of manganiferous ore leaching with sulphuric acid and lactose , 2001 .

[9]  P. Gélinas,et al.  Comparison of methods for the estimation of pyrite oxidation rate in a waste rock pile at Mine Doyon site, Quebec, Canada , 2006 .

[10]  S. Harrison,et al.  An experimental study of the long-term bioleaching of large sphalerite ore particles in a circulating fluid fixed-bed reactor , 2012 .

[11]  J. A. Finch,et al.  Galvanic Interaction Studies on Sulphide Minerals , 1988 .

[12]  I. González,et al.  A comparative study of electrochemical behavior of chalcopyrite, chalcocite and bornite in sulfuric acid solution , 2002 .

[13]  M. G. Dastidar,et al.  Factors limiting bacterial iron oxidation in biodesulphurization system , 2004 .

[14]  C. Prestidge,et al.  The electrochemistry of PbII activated sphalerite in relation to flotation , 2001 .

[15]  J-P. Franzidis,et al.  Use of X-ray computed tomography to investigate crack distribution and mineral dissemination in sphalerite ore particles , 2011 .

[16]  R. Smart,et al.  A comparison of the kinetics and mechanism of acid leaching of sphalerite containing low and high concentrations of iron , 2004 .

[17]  A. Akcil,et al.  Bioleaching of complex zinc sulphides using mesophilic and thermophilic bacteria: comparative importance of pH and iron , 2004 .

[18]  Yousef Ghorbani,et al.  Large particle effects in chemical/biochemical heap leach processes – A review , 2011 .

[19]  M. Malmström,et al.  Combined effects of spatially variable flow and mineralogy on the attenuation of acid mine drainage in groundwater , 2008 .

[20]  R. Leonard,et al.  Mica Weathering Rates as Related to Mica Type and Composition , 1970 .

[21]  David Dreisinger,et al.  Copper leaching from primary sulfides: Options for biological and chemical extraction of copper , 2006 .

[22]  O. Tuovinen,et al.  Chemical and bacterial leaching of metals from black schist sulfide minerals in shake flasks , 2012 .

[23]  Knona C. Liddell,et al.  Shrinking core models in hydrometallurgy: What students are not being told about the pseudo-steady approximation , 2005 .

[24]  H. Tributsch,et al.  Reasons why 'Leptospirillum'-like species rather than Thiobacillus ferrooxidans are the dominant iron-oxidizing bacteria in many commercial processes for the biooxidation of pyrite and related ores. , 1999, Microbiology.

[25]  Robert Schouwstra,et al.  Understanding Gamsberg - A geometallurgical study of a large stratiform zinc deposit , 2010 .

[26]  I. González,et al.  An experimental strategy to determine galvanic interactions affecting the reactivity of sulfide mineral concentrates , 2005 .

[27]  Helen R. Watling,et al.  The bioleaching of sulphide minerals with emphasis on copper sulphides — A review , 2006 .

[28]  Fernando Acevedo,et al.  Present and future of bioleaching in developing countries , 2002 .

[29]  J. T. Kalala,et al.  Investigation of particles with high crack density produced by HPGR and its effect on the redistribution of the particle size fraction in heaps , 2013 .

[30]  O. Tuovinen,et al.  Dissolution and structural alteration of phlogopite mediated by proton attack and bacterial oxidation of ferrous iron , 2001 .

[31]  J-P. Franzidis,et al.  Investigation and modelling of the progression of zinc leaching from large sphalerite ore particles , 2013 .

[32]  O. Tuovinen,et al.  Bacterial leaching of complex sulfide ore samples in bench-scale column reactors , 1995 .

[33]  O. Tuovinen,et al.  Weathering of phlogopite in simulated bioleaching solutions , 2011 .

[34]  Li Zhou,et al.  Galvanic interactions between metal sulfide minerals in a flowing system: Implications for mines environmental restoration , 2008 .

[35]  D. Rawlings,et al.  Characteristics and adaptability of iron- and sulfur-oxidizing microorganisms used for the recovery of metals from minerals and their concentrates , 2005, Microbial cell factories.

[36]  Zincian högbomite as an exploration guide to metamorphosed massive sulphide deposits , 1989 .