Tof-SIMS and Principal Components Analyses: Applications to Mineral Flotation

Transcription

1 Tof-SIMS and Principal Components Analyses: Applications to Mineral Flotation Brian Hart, Mark Biesinger, James Francis, Western University of Western Ontario Roger Smart Applied Center for Structural and Synchrotron Studies University of South Australia

2 CONCENTRATE (FROTH) FLOTATION PROCESS: THE MODEL VALUE/ NON-VALUE AGGREGATES VALUE AGGREGATES INADVERTENTLY ACTIVATED NON- VALUE OR NEXT STAGE SULFIDE What do we need to know? Distribution of various phases in process BUBBLE VALUE SULFIDE (EG PbS,ZnS,CuS) COLLECTOR ADSORBED (HYDROPHOBIC); ACTIVATED (CONDITIONED) COMPOSITES (NOT LIBERATED) PULP TAIL NON-VALUE SULFIDE (EG FeS,FeS 2 ) OR VALUE SULFIDE FOR NEXT STAGE (NOT ACTIVATED) GANGUE (EG SILICATE, ALUMINOSILICATE) Factors affecting distribution What are we after: Hydrophobic/Hydrophilic Balance - by particle (average, distribution) - by phase

3 Development of a Protocol PCA Analyses and Mineral Identification LAB Study: Copper transfer: chalcopyrite/pyrite/sphalerite mineral mixture conditioned at ph 9 for 20min

4 Total Ion Images: 256 x 256 pixel data set obtained over a mass range of 1000 amu; 6.5 x 10 7 data points Log Scale Goal: Pick out individual mineral species Linear Scale

5 Fe Zn PC2 Cu m/z Positive: Auto Scaled Factor Loadings PC2 0-1 Fe Positive: Mean Centered m/z 1 Cu PC4 0 Fe Positive: Mean Centered m/z

6 G G In In In In In G PCA: Mineral Identification - rite (FeS 2 ) - alcopyrite (CuFeS 2 ) - halerite (ZnS) G - Gangue In - Indium Log Scale

7 PCA: Mineral Identification, ROI Analyses Mean iron (Fe) and zinc (Zn) Intensities and confidence intervals for pyrite () and sphalerite (h) mineral phases in a chalcopyrite/pyrite/sphalerite mineral mixture conditioned at ph 9 for 20min Normalized intensity Fe Fe h Zn Zn h

8 Normalized Intensity Analytical Surface emistry Applied to Mineral Flotation PCA: Mineral Identification Mean Copper Intensities and confidence intervals for pyrite () and sphalerite (h) mineral phases in a chalcopyrite/pyrite/sphalerite mineral mixture conditioned at ph 9 for 20min Cu transfer from Cpy 0.10 Favored on sphalerite surface 63 Cu h h 63 Cu 65 Cu Mineral species and Ion 65 Cu

9 Case Study: The Inco Bessemer Matte Processing Plant Separates chalcocite (Cu 2 S, Cc) from heazlewoodite (Ni 3 S 2, Hz) by froth flotation Diphenylguanidine (DPG) is the collector/frother Flotation banks 101A and 101B diphenylguanidine Uses two Denver DR300 Flotation banks (shown on right),each of which consists of four cells; A through D

10 INCO Matte Concentrator Problem: grade/loss of selectivity between chalcocite (Cc) and heazlewoodite (Hz) through the concentrator. Mechanisms: 1. inadvertent activation of Hz by dissolved copper ions; depression of Cc by dissolved nickel ions; 2. lack of selectivity of the diphenylguanidine (DPG) collector

11 INCO Matte Concentrator INCO CON ROI Results Mean normalized ion intensities for Ni and Cu on the surface of: Heazlewoodite Hz (Ni-gr) alcocite Cc (Cu-gr) Normalized Intensity Ni-gr Ni 58 Cu-gr Ni 58 Ni distribution Ni; Hz:Cc = 19 Ni-gr Ni 60 Cu-gr Ni 60 Cu distribution Ni-gr Cu 63 Cu-gr Cu 63 Ni-gr Cu 65 Cu-gr Cu 65 Indicates Cu transfer from Cc to Hz

12 INCO Matte Concentrator ROI Results Mean normalized ion intensities for Ni and Cu on the surface of: Heazlewoodite Hz (Ni-gr) alcocite Cc (Cu-gr) Normailzed Intensity Ni-gr Ni 58 INCO TAIL Cu-gr Ni 58 Ni distribution Ni; Hz:Cc = 2 Ni-gr Ni 60 Cu-gr Ni 60 Cu distribution 0.00 Ni-gr Cu 63 Indicates Ni transfer from Hz to Cc Cu-gr Cu 63 Ni-gr Cu 65 Cu-gr Cu 65

13 INCO Matte Concentrator: Conclusions Mechanisms: Cu transfer via solution from alcocite to Heazlewoodite Yes, activated flotation of Hz in Con. Ni transfer via solution from Heazlewoodite to alcocite Yes suppressed flotation of Cc to Tails. The lack of DPG selectivity as a collector Yes, potential limited control of the selectivity since it is clear that Cu is found on both CC and Hz mineral surfaces during processing.

14 PC-2 PC-3 50 x 50 microns C6H11NO2 C6H10NO2 C5H11NO2 C5H9NO2 C2H7NO2 C5H7 Cu 63 Ni 58 Fe 56 C4H5 C3H8N CH4N2 C3H7 Ca K CH4N Si Al Mg Na NH4 CH3 PC4 PC3 PC2 Example II: Pentlandite Recovery PC-2: Gangue PC-3: Ni phase Pentalndite PC-4: Cu phases alcopyrite PC-4 CH2 CH

15 Ni Ni Loss Loss Fe-Ni Con ROI Fe-Cu Con ROI Fe-Ni Tail ROI Example II: Pentlandite Recovery Normalized Intensity Gangue Increase Gangue Fe-Cu Tail ROI Cu Cu Loss Loss Fe56 / 2 Ni58 Cu63 FeOH x 2 Fe-Ni Con ROI Fe-Cu Con ROI Fe-Ni Tail ROI Fe-Cu Tail ROI Ca K Mg Al Na Si Fe-Ni: Pentlandite Fe-Cu: alcopyrite Surface exposure Cu and Ni > in Cons vs Tails Gangue phases (Na, K, lesser Ca, Al, Si) enriched in Tail samples

16 Example II: Pentlandite Recovery Normalized Intensity Fe-Ni Con ROI Fe-Cu Con ROI Fe-Ni Tail ROI Fe-Cu Tail ROI C2H5 C4H5 CH3 C5H7 Collector molecule mass fragments No apparent selectivity for collector between species or streams

17 Summary: Diagnosis of the surface chemical factors influencing flotation separation requires measurement of the hydrophobic and hydrophilic species that are statistically different between the concentrate and tail streams. Meaningful results requires reliable identification of specific mineral particles. Statistical methods, based on the monolayer-sensitive ToF-SIMS imaging techniques in combination with PCA analyses have been developed towards this ultimate aim. Limitations: Particle size