Issue 11, p. 285 (2022)

  Oral

The evolution of the mechanically agitated hopper in Anglo American Platinum

  • Neressa Sukha  
  • Coert Kruger
  • Ndala Kobe
144 Oxford Road, Rosebank, Johannesburg, South Africa
[email protected]
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144 Oxford Road, Rosebank, Johannesburg, South Africa
[email protected]
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 Corresponding Author
144 Oxford Road, Rosebank, Johannesburg, South Africa
[email protected]
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For Anglo American Platinum (AAP) to reach their burning ambition goal of doubling the Earnings Before Interest, Taxes, Depreciation, and Amortization (EBITDA) by 2023, sites are required to adopt an alternative approach to improve representativeness of metal accounting samples given the increase in grind and throughput demand. The success of optimization projects will rely heavily on metal accounting data being accurate so that improvements declared are based on sound samples and assay measurements. The 60 litre mechanically agitated hopper (MAH) was initially developed and ratified in order to overcome particle segregation evident in the 20-litre conventional, compressed air-agitated hoppers of vezin type sampling systems. A sustained plant accountability performance within the range of 95-105% was realized due to the correction of the previously overstated feed grade by means of a more representative sample. Pierre Gy’s rule of thumb of 30 increments per sampling campaign has not been proven and documented for the Platinum Group Metals (PGM) industry. The MAH however with additional volume capacity allows for flexibility to increase the primary sampling increments per shift from ± 32 to ± 96 to cater for process variability (thereby reducing distributional heterogeneity) without increasing the overall resulting final sample mass. Additional technology and larger 110/220 litre capacity hoppers have been deployed. Enhancements include a wash water and drainage system, an improved trash screen design and high/low hopper level sensors. The MAH principle of operation has also been expanded to cater for a double (3-drive) stage sampling system as well as a triple (5-drive) stage sampling system. It is believed that the latest MAH design will satisfy the Theory of Sampling principles and therefore a motivation for an industrial roll out of the innovation within AAP is underway.

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