Page 294 - Annual Report 2020

Copper

Ore Reserves
As at 30 June 2020 As at 30 June 2019
Proved Reserves Probable Reserves Total Reserves Reserve BHP Total Reserves Reserve
Commodity Life Interest Life
Deposit (1) (7) (8) (9) Ore Type Mt %TCu %SCu ppmMo Mt %TCu %SCu ppmMo Mt %TCu %SCu ppmMo (years) % Mt %TCu %SCu ppmMo (years)
Copper Operations
Escondida (10) Oxide 77 0.64 − − 129 0.55 − − 206 0.58 − − 58 57.5 228 0.60 − − 58
Sulphide 3,420 0.70 − − 1,790 0.57 − − 5,210 0.66 − − 5,420 0.65 − −
Sulphide Leach 1,330 0.42 − − 326 0.41 − − 1,660 0.42 − − 1,670 0.42 − −
Cerro Colorado (11) Oxide 29 0.58 0.42 − 6.0 0.58 0.42 − 35 0.58 0.42 − 3.4 100 41 0.58 0.42 − 4.3
Supergene Sulphide 14 0.57 0.17 − 4.0 0.63 0.15 − 18 0.58 0.17 − 24 0.61 0.15 −
Transitional Sulphide 12 0.51 0.10 − 1.6 0.51 0.09 − 14 0.51 0.10 − 17 0.49 0.10 −
Spence (12) Oxide 31 0.61 0.42 − 0.11 0.95 0.63 − 31 0.61 0.42 − 36 100 21 0.63 0.42 − 46
Oxide Low Solubility 9.9 0.68 0.29 − 0.59 0.56 0.31 − 10 0.67 0.30 − 14 0.68 0.28 −
Supergene Sulphide 100 0.62 0.10 − 6.6 0.43 0.08 − 107 0.61 0.10 − 131 0.64 0.13 −
Transitional Sulphide 22 0.67 0.05 100 0.51 0.53 0.04 60 23 0.66 0.05 95 20 0.67 0.06 100
Hypogene Sulphide 615 0.46 0.02 180 694 0.46 0.02 130 1,310 0.46 0.02 150 1,310 0.45 0.02 160
ROM − − − − − − − − − − − − 0.74 0.65 0.06 −
Copper Uranium Gold Operations Mt %Cu kg/tU 3 O 8 g/tAu g/tAg Mt %Cu kg/tU 3 O 8 g/tAu g/tAg Mt %Cu kg/tU 3 O 8 g/tAu g/tAg Mt %Cu kg/tU 3 O 8 g/tAu g/tAg
Olympic Dam (13) UG Sulphide 210 1.92 0.58 0.74 4 238 1.85 0.56 0.65 4 448 1.88 0.57 0.69 4 43 100 537 1.87 0.57 0.71 4 54
Low-grade − − − − − 25 0.86 0.29 0.34 2 25 0.86 0.29 0.34 2 24 0.99 0.33 0.40 2
Copper Zinc Operations Mt %Cu %Zn g/tAg ppmMo Mt %Cu %Zn g/tAg ppmMo Mt %Cu %Zn g/tAg ppmMo Mt %Cu %Zn g/tAg ppmMo
Antamina (14) Sulphide Cu only 137 0.92 0.12 6 350 108 0.97 0.15 8 330 245 0.94 0.13 7 340 7.7 33.75 266 0.97 0.16 7 370 8.8
Sulphide Cu-Zn 69 0.89 2.09 13 80 94 0.82 2.18 13 80 163 0.85 2.14 13 80 202 0.82 1.97 15 70
(7) Approximate drill hole spacings used to classify the reserves were:
Deposit Proved Reserves Probable Reserves
Escondida Oxide: 30m x 30m Oxide: 45m x 45m
Sulphide: 50m x 50m Sulphide: 90m x 90m
Sulphide Leach: 60m x 60m Sulphide Leach: 115m x 115m
Cerro Colorado 40m to 50m 100m
Spence Oxide & Oxide Low Solubility: maximum 50m x 50m 100m x 100m for all Ore Types
Supergene Sulphide, Transitional Sulphide &
Hypogene Sulphide: maximum 70m x 70m
Olympic Dam 20m to 35m 35m to 70m
Antamina 25m to 45m 40m to 80m
(8) Ore delivered to process plant.
(9) Metallurgical recoveries for the operations were:
Deposit Metallurgical Recovery
Escondida Oxide: 59%
Sulphide: 83%
Sulphide Leach: 42%
Cerro Colorado Oxide: 75%
Supergene Sulphide: 80%
Transitional Sulphide: 65%
Spence Oxide & Oxide Low Solubility: 80%
Supergene Sulphide: 82%
Transitional Sulphide & Hypogene Sulphide:
Cu 86%, Mo 56%
Olympic Dam Cu 94%, U 3 O 8 68%, Au 70%, Ag 63%
Antamina Sulphide Cu only: Cu 93%, Zn 0%, Ag 80%, Mo 65%
Sulphide Cu-Zn: Cu 78%, Zn 80%, Ag 63%, Mo 0%
(10) Escondida – The decrease in Oxide ore type was mainly due to depletion. Incorporated within the Reserve Life calculation were Oxide and Sulphide Leach ore types,
which contribute 10 years and 24 years respectively.
(11) Cerro Colorado – The decrease in Ore Reserves was mainly due to depletion with Reserve Life constrained by mining permit expiry in 2023. Transitional Sulphide ore
type recovery based on metallurgical testwork.
(12) Spence – The increase in Oxide and Transitional Sulphide ore types was due to an update in the resource estimate supported by additional drilling. The decrease in
Oxide Low Solubility, Supergene Sulphide and ROM ore types was mainly due to depletion. Reduction in Reserve Life from 46 years to 36 years was mainly due to
increased overall processing rate assumptions. Transitional Sulphide and Hypogene Sulphide ore type recoveries are based on metallurgical testwork.
(13) Olympic Dam – The decrease in UG Sulphide ore type and reduction in Reserve Life was due to updated commodity prices, mine stope design changes and
modifying factors partially offset by an update in the resource estimate supported by additional drilling.
(14) Antamina – The decrease in the Ore Reserves and reduction in Reserve Life was mainly due to depletion partially offset by an update in the resource estimate and
changes to reserves classification.

292 BHP Annual Report 2020