Geoscience Reference
In-Depth Information
ing pass, or the number of composites used, and so on. All
scripts, legends, and data should be available for easy plot-
ting to compare original data with estimated block grades. It
is still important to have, on a large scale map, key sections
and plans, properly signed by the operator, the internal qual-
ity control person, and the auditor.
For each general task in the resource modeling process,
the following suggested audit trail and documentation can
be considered adequate to satisfy an auditor in its request for
data and documentation.
Grade Estimation:
Document the method, with the param-
eters files used, and validations performed. Maintain all
relevant files and ensure that the block model has all the nec-
essary variables for checking.
Resource Classification:
Document methodology. What
criteria were used? How was it implemented? Document the
checks performed.
Resource Validation:
Document in detail, summarizing
all the checks performed, and explaining why the resource
model is deemed adequate for its objective. Include state-
ments regarding the main assumptions, limitations, and risk
areas perceived. What are the recommended risk mitigation
procedures?
Database:
Description of data fields and tables; descrip-
tion of prior audits and reviews; description of procedures,
checks, validations (maintenance) that jointly ensure that the
database is kept clean, and that new data is incorporated with
the same standards.
Resource Reporting:
Document in detail the checks per-
formed that the reported tonnages and grades correspond to
the estimated model. Use appropriate number of significant
digits. Include comparisons with previous models, and with
reference (production models), and explain the reasons for
the observed differences.
In summary, the audit trail has to demonstrate to third par-
ties that each step of the process was completed with appro-
priate methodology, which was implemented correctly, and
was thoroughly validated.
Loading Data Into Modeling Software:
Scripts or run
files used to upload; is it an OBDC connection? Document
the connection setup, the fields and files manipulation; and
how the data is selected from the database.
Checking the Loaded Data:
Document what checks have
been made; why are they sufficient to ensure correct loading?
Geologic Modeling:
Document and describe rationale
for methodology chosen. Is it appropriate for this type of
deposit? What criteria have been used to interpret geology?
What checks have been made to ensure the quality of the
output models?
15.4
Future Trends
Trained professionals for resource estimation are hard to
come by. The cyclic nature of the mining industry means that
a relative lack of staff today likely means a glut tomorrow;
however, it is still a general trend that there are relatively few
highly trained people for resource estimation. In the last few
years, during the recent and unprecedented non-renewable
resources boom, this has become a major hurdle in project
development. The larger mining companies are likely to out-
source more work to consulting companies, but consulting
companies also have challenges finding and retaining pro-
fessionals. Moreover, there are few undergraduate programs
that teach geostatistics or resource estimation; new profes-
sionals are not always willing to make the sacrifices that
a solid professional development would require, and if so,
much of the training is done on the job through postgraduate
courses and mentoring.
There will be a trend toward increasing automation of
many steps in resource estimation. This has many advan-
tages including less professional time required, repeatability,
transparency and easy updating with additional drilling. This
also has many disadvantages. It will be easier to make mis-
takes, create models that are not geologically realistic and
portray a false sense of confidence in the models because
Exploratory Data Analysis:
Easy to access, organized
archive of parameter files, run files, and plots. Use backup
binders, not just electronic files. Document the assumptions
and conclusions reached.
Estimation Domain Definition:
Justification for logic;
description of the process; supporting geology and statistical
evidence; description of the sensitivities, if possible. Checks
performed to confirm the decision.
Block Model:
Documentation and description of model lim-
its; block size(s), with partial or whole blocks; is it rotated?
Was it built using a coordinate rotations and transformation?
Project and world coordinates. How was the geology and
estimation domains assigned?
Variography:
Documentation of the estimators used; data
transformations? Document parameters for obtaining the
directional variograms, and the criteria used in modeling
them. Document any data selection. By domain, or have
domains been combined for practical reasons? Document all
other assumptions made.