Geoscience Reference
In-Depth Information
F i g . 11.11
Example of long-term versus mine reported reconciliations. Observe that after 05/1997 the reconciliation changes. The factors have
not been adjusted to overall metal production
mining, and metallurgy departments, which includes a clear
delineation of responsibilities, thus ensuring proper informa-
tion gathering and processing.
The first requirement is essential because production rec-
onciliation can quickly become a bone of contention among
the groups involved. Reconciliation can be a minefield be-
cause of inevitable organizational politics. As readers that
are or have been involved in operations would all too easily
recognize, metallurgists will tend to blame production rec-
onciliation discrepancies on the mine for lower head grades,
while the mining department in turn will tend to blame the
geology department for poor predictive models; and the ge-
ology department will eventually propose that more in-fill
drilling is required to solve the mine to mill reconciliation
discrepancies. Therefore, the best way to ensure a good faith
effort from all involved is for an Operations Manager to rec-
ognize the importance of the issue, and to adequately dis-
tribute responsibilities and prioritize the tasks involved in a
reconciliation program.
Finally, the procedures and data sources should be main-
tained constant through time, as much as possible, to allow
for relevant comparisons regarding model, mine, and plant
performances. There are multiple options for establishing a
reconciliation program, but in all cases it should be devel-
oped from basic principles as discussed. Figure
11.11
shows
an example of monthly reconciliations based on raw, non-ad-
justed data, and thus more likely better reflecting operations
performance. In this case, note how reconciliations improve
at a certain point in time after introducing corrective mea-
sures in the modeling process.
11.6.2
Suggested Reconciliation Procedures
A simple but systematic reconciliation approach is proposed
to compare Long-term block models to Short-term models,
grade control models, mine reported, and mill feed informa-
tion, if available.
The reconciliation procedure is common in industry.
Most operations that reconcile production against predictive
models do so utilizing some variant of comparison factors,
sometimes known as Mine Call factors. The presentation
here is based on an expanded scheme from that proposed by
Parker (
2012
).
The performance factors proposed here are intended to
separately evaluate the performance of long-term models
(resource and reserve block models), short-term models
(quarterly or monthly, see Chap. 13), daily grade control
models, and dilution and ore losses resulting from mining
(operational dilution). These comparisons ideally are an-
chored in reliable
head grades and tonnages
to the process-
ing facilities. The information should be compared based on
a reasonable production period, most commonly on a month-
ly basis, although there can be exceptions to this.
