Assessment of the Impact of Non-Additivity in the Estimation of Iron Ore

Attributes

Iron Ore 2013, 12th – 14th August 2013

Alastair Cornah

Outline

Planning, development and execution

Value add

Heterogeneous in situ chemical and physical attributes

Homogeneous product chemical and physical attributes

Product marketingDeposit level sequencing and blending

Life of mine planning and sequencing

Production planning and sequencingMining and processingStockpiling and blending

Data collection, but incomplete knowledge

Sparse drillholes

Infill drilling

Blast holes / grade control drilling

Local block models

Global models, local block models

Grade control models

Spatial estimation models

Mean in situ grades

Mean product yields

Mean product grades

Mean in situ grades

Mean product yields

Mean product grades

Destination 2

Destination 1

In situ grades

Product yields

Product grades

variable

Res

ponse

Linear average of data

understates responseR

esponse

variable

Linear average of data

overstates response

Rock Response Properties

Primary Rock Properties

Energy or Process

Primary – Response Framework, modified from Coward et al., 2009.

In situ geochemical grades

Bulk and particle density

Mineral abundances

Material type abundances

Texture

Primary Response

Davis Tube concentrate recovery and grades

Porosity

Dry crush and screen / beneficiation product yields and grades

Material handling, degradation metrics

Sinter performance metrics (TI, RDI, RI)

Compare between:1. The average of the ratios; and2. The ratio of the averages

Additive variables are shown in blue, non additive variables are shown in red using the following notation:

Direct (illegitimate) approach

Samples or nodes Averaged samples or nodes

Indirect (legitimate) approach

Global estimation approach % Fe units recovered to concentrate

% Fe units lost to tails

Direct (illegitimate non-additive procedure)

76.36 23.64

Indirect (legitimate additive procedure)

76.60 23.40

Direct (illegitimate non-additive procedure)

Realisation 5 / 25

Direct (illegitimate non-additive procedure)

Realisation 10 / 25

Direct (illegitimate non-additive procedure)

Realisation 15 / 25

Direct (illegitimate non-additive procedure)

Realisation 20 / 25

Indirect (legitimate

additive procedure)

Realisation 5 / 25

Indirect (legitimate

additive procedure)

Realisation 10 / 25

Indirect (legitimate

additive procedure)

Realisation 15 / 25

Indirect (legitimate

additive procedure)

Realisation 20 / 25

VARIABLE Mean (biased - unbiased)

Realisation 1 -0.2

Realisation 2 -0.2

Realisation 3 -0.21

Realisation 4 -0.23

Realisation 5 -0.35

Realisation 6 -0.29

Realisation 7 -0.28

Realisation 8 -0.24

Realisation 9 -0.34

Realisation 10 -0.23

Realisation 11 -0.17

Realisation 12 -0.67

Realisation 13 -0.24

Realisation 14 -0.11

Realisation 15 -0.4

Realisation 16 -0.65

Realisation 17 -0.33

Realisation 18 -0.43

Realisation 19 -0.12

Realisation 20 -0.19

Realisation 21 -0.86

Realisation 22 -0.57

Realisation 23 -0.04

Realisation 24 -0.39

Realisation 25 -0.1

Residuals, %

(biased – unbiased)

Conclusions and Recommendations

Key References:

Carrasco P., Chiles J.P. and Seguret S., 2008. Additivity, Metallurgical Recovery and Grade. In Geostats 2008: VIII International Geostatistics Congress (eds: J. Ortiz and X. Emery), Santiago, pp.465-476. Springer.

Coward, S., Vann J., Dunham S., and Stewart M., 2009, The Primary-Response Framework for Geometallurgical Variables. In Proceedings Seventh International Mining Geology Conference, pp.109-113. The Australasian Institute of Mining and Metallurgy: Melbourne.

Correspondence: ac@qgroup.net.au