Integrated Liberation Leach

Transcription

1 AMIRA P420E Gold Processing Technology Integrated Liberation Leach Characterisation Method Development and Modelling Examples Sponsors Review Meeting May 30, 2016, Perth

2 Gold Technology Group

3 Gold Technology Group Overview: Industry sponsored research group Western Australian School of Mines, Curtin Uni 30+ years of gold research Gold processing technology transfer courses Gold processing modelling and optimisation workshops Gravity (BCC (Batch Centrifugal Concentrator) & Jig) SIMCIL (Standard, High Ag & Cu Cu) ILLM (Integrated Liberation Leach Model)

4 Gravity Recoverable Gold (GRG) Model developed from Laplante s gravity research and GRG ore characterisation test

5 AMIRA P420 Gravity - BCC A population balance model in which matrices are used to define each process and stream GRG size distribution matrix for the ore Primary and secondary gravity recovery matrices Classification matrix (GRG behaviour in cyclone) Grinding matrix using conventional breakage (b i,j ) and selection functions (S) and dimensionless residence time in mill (τ) Web based (2004), flexible and user friendly Applicable for optimisation, retrofitting and greenfields Milling circuits containing Knelson and Falcon BCCs

6 Gravity Recovery Questions What it is the effect on GRG recovery if we change: Feed source Feed rate Type of concentrator # of units Ore type Head grade

7 AMIRA P420 SIMCIL A web based simulation tool for CIL/CIP circuit optimisation (2002) Computational basis -Mintek model for leaching kinetics (2 nd order rate EQ) -Fleming/ Nicol model for adsorption kinetics -Modified Freundlich isotherm (equilibrium carbon adsorption) Five parameters define leaching and adsorption behaviour -leaching parameters derived from lab tests or plant data -adsorption parameters derived from plant data Applicable for optimisation, retrofitting and greenfields

8 Limitation of SIMCIL Parameters

9 SIMCIL Questions What is the effect on leach recovery if we change: Feed rate or grade Leach rate Carbon activity Carbon mass in circuit Carbon distribution in circuit Carbon movement rate (elution rate) Barren carbon loading Number of active tanks (lose a tank for maintenance) Grind size??? Total recovery (gravity + leach)???

10 What is the ILLM? Integrated Liberation Leach Model (ILLM): A single model uses the gravity and leach circuit recoveries to predict total gold recoveries Essentially combines current BCC model and a modified SIMCIL in a single package Original Development: Curtin Gold Group, CSIRO and Anglo Gold Sunrise Dam Samples Rolled into P420

11 How was SIMCIL modified? 1st order leach rate equation (vs 2nd Order) Found to be a better fit for the leaching of GRG Leach rates and solids grades of sized GRG and non-grg samples determined from lab test Bottle roll cyanidation test Controlled DO No Auto-Calibration

12 GRG Testwork Flowsheet kg Sample +850µm Crushing Screen 100% -850µm conc tail LKC Stage 1 Screen 850 to -20 µm size-by-size assay conc Screen Splitting 27Kg Grinding 425 to -20 µm size-by-size assay 45-50% -75µm LKC Stage 2 tail conc Screen Stage 1 tail Grinding LKC Stage 3 80%-75µm tail Screen 212 to 20 µm Size-by-size assay main tail

13 ILLM Testwork Flowsheet (GRG) (non-grg)

14 ILLM Methodology Benefits Large sample mass and sequential sample processing minimise high sampling errors and poor reproducibility. Performed with relatively simple, low cost laboratory equipment. Independently measures the GRG and non-grg leaching characteristics. The approach allows the liberation comportment of the GRG and non-grg to be quantified, providing recoverygrind size responses for both types of gold occurrences.

15 3 Stage GRG Results

16 Leaching of GRG

17 Example of Coarsening Grind

18 Example of Carbon Management

19 Conclusions A new ore characterisation test has been developed to provide the data for an integrated liberation-leach model. The test procedure separates the GRG and non GRG, allowing their leaching characteristics to be measured independently. The use of a large sample mass and sequential sample processing in the characterisation test minimises sampling error and improves test reproducibility.

20 Conclusions The testwork can be performed with relatively simple, low cost laboratory equipment. Data from ore characterisation test can be used with the ILLM to predict gravity, leach and adsorption recoveries. To date, more than 10 ores from Australia, Africa and South America have been characterised using the ILLM test procedure.

21 Conclusions The ILLM has been validated by modelling an Australian gold plant and used as an optimisation tool for a number of operating gold plants. With further validation studies, it is envisaged that the ILLM will prove to be a valuable aid for the design of plant expansions and new plants. The ILLM provides an excellent platform for the education and training of metallurgists and process operators.

22 Acknowledgements The authors wish to the AMIRA P420E sponsors for financial and technical support. AngloGold Ashanti Australian Gold Reagents Barrick Gold Gekko Systems Harmony Kemix Magotteaux Newcrest Mining Newmont Norton Gold Fields Orica Australia Rangold St Barbara Tenova