REG - Thor Mining PLC - Kapunda Copper Resource <Origin Href="QuoteRef">THRL.L</Origin> - Part 5
12/02/2018 07:05
- Part 5: For the preceding part double click ID:nRSL5160Ed
drilling periods available on "South Australian Resources Information Gateway" (SARIG). Terramin was also able to obtain digital data sets of the drill data from Copper Range Ltd and the digital data set used by Stuart Metals NL for their 1992 Resource Estimate.
Resource estimation purposes.
· Data validation procedures used. Drillhole data was extracted from the original reports by Terramin and crossed checked with the digital datasets from Stuart Metals and Copper Range. Where differences
were found between the data contained in the original company reports and the provided Stuart Metals database, the original companies' values were used. The data was then
imported into a Maxwell Geo Services' DataShed and QAQCR were used to validate the data viz; overlapping intervals, excessive drillhole deviation, assay QAQC. Secondary
validation by Maptek's Vulcan software and visual validation.
Site visits · Comment on any site visits undertaken by the Competent Person and the outcome of those visits. The Competent Person has undertaken several site visits to the Kapunda project. These visits have verified that the dimensions of the physical site correspond with dimensions implied by the data sets. Copper oxide in the form of malachite is present in the mullock piles and copper efflorescence visible on many of the historic pit faces. Evidence of previous mining operations is visible with numerous open cuts, shafts and waste dumps still clearly visible. Visits have also been undertaken at the South Australian Drill Core Reference Library where over 100 Kapunda drillholes are stored.
· If no site visits have been undertaken indicate why this is the case. Site visits have been undertaken.
Geological interpretation · Confidence in (or conversely, the uncertainty of) the geological interpretation of the mineral deposit. The extensive surface and underground mining of the Kapunda lodes combined with the large amount of diamond drilling history of the Kapunda projects implies confidence in the current geological interpretation There are no alternative geological models of the secondary copper mineralisation (copper oxides and secondary copper sulphides). The vertical extent of secondary copper mineralisation modelled by Terramin using drillhole data is broadly comparable to the line "approximate lower limit of secondary enrichment" mapped out on a longitudinal section produced by the South Australian Mines Department in 1942 (Plan N2788).
· Nature of the data used and of any assumptions made. The 2018 Kapunda Resource utilized data from 78 diamond and 109 percussion holes with a combined meterage of 22,712.8m. Original lab assays were used. Resampling and lab
analysis of selected diamond core intervals and xrf analysis of drill chips from percussion holes stored at the South Australian Drill Core Reference Library by both
Copper Range Pty and Terramin confirmed the appropriateness and accuracy of historic assay methods. All original density measurements were considered inappropriate as
they did not make allowances for porosity of the rock. ECR and Terramin collected 202 new density measurements from 19 drillholes using a modified Archimedes method.
Historically the assumed density was between 2.0 t/m3 (ACC and Stuart Minerals) and 2.4 t/m3 (BHS and Northland) whereas the average calculated density of the 2018
Mineral Resource estimate is only 1.84 t/m3.
· The effect, if any, of alternative interpretations on Mineral Resource estimation. No alternative interpretations for the secondary copper enrichment have been put forward for serious consideration. Alternative geological interpretations may be
developed with further drilling but in the Competent Person's opinion they would not significantly affect the global resource estimate, but could affect local estimates.
· The use of geology in guiding and controlling Mineral Resource estimation. The 2018 Mineral Resource estimate was focused on defining the extent and nature of secondary (oxide/supergene) copper mineralisation. Important boundaries modelled were
the top and base of copper oxides, top and base of secondary sulphides and top of primary copper sulphides. The lower limit of (significant) weathering corresponds with
the base of secondary copper mineralisation. Detailed geological control has not been attempted at this stage. Primary copper mineralisation was bounded on the east by
the Mine Fault, which dips 65°E. The old workings immediately west of this structure occur principally in sets of en echelon lodes comprising of quartz-sulphide filled
fractures of which 28 were worked at an average width of 45cm.
· The factors affecting continuity both of grade and geology. The main controlling features of the secondary copper are seen to be proximity to primary mineralisation, the water table and the partial replacement of pyritic horizons
by copper within the supergene zone and depth of weathering.
Dimensions · The extent and variability of the Mineral Resource expressed as length (along strike or otherwise), plan width, and depth below surface to the upper and lower The Mineral Resource has a strike length of 1700m, a plan width of 500m and has been limited to a maximum depth of 100m. Copper mineralisation was historically mined from surface and copper efflorescence is visible on many of the pit faces.
limits of the Mineral Resource.
Estimation and modelling techniques · The nature and appropriateness of the estimation technique(s) applied and key assumptions, including treatment of extreme grade values, domaining, interpolation Wireframes modelled included; top and base of copper oxide mineralisation, top and base of secondary copper sulphides and top of primary copper sulphides. Compositing of drillhole samples was completed at 2m (downhole) intervals, with composites flagged to identify the copper's mineralogy. The 2m composites were used for statistical analysis and continuity modeling.
parameters and maximum distance of extrapolation from data points. If a computer assisted estimation method was chosen include a description of computer software and
Variogram models for copper were developed using Snowden's Supervisor software. Ordinary kriging estimation technique was used for estimation of copper grade. Estimation of blocks was limited to a maximum of three composites per hole from a maximum of three drillholes. Maximum distance of extrapolation was limited to 100m. There are no "extreme grade values" as all copper grades of the 2m composites were below the average historic production grade of 19% copper. The maximum assay from the oxide and secondary sulphide portions of the Resource estimate were respectively 6.3% and 17.7% copper. All geological modelling, block model construction, grade interpolation and reporting were completed using Maptek's Vulcan software.
parameters used.
· The availability of check estimates, previous estimates and/or mine production records and whether the Mineral Resource estimate takes appropriate account of such data. Previous Mineral Resource estimates, calculated for mining by open cut are;· BHS (1969) - 5.5Mt @ 0.74% copper for 41,000t of contained metal.· Northland (1978)
- 6.3Mt @ 1.50% copper for 94,000t of contained metal.· ACC (1989) - 7.2 Mt @ 0.83% copper for 60,000 tonnes of contained metal· Stuart Metals (1992) - 4.3 Mt
@ 1.10% copper for 47,000 tonnes of contained metal.·
· The assumptions made regarding recovery of by-products. No assumptions made. Potential by-products have not been modelled.
· Estimation of deleterious elements or other non-grade variables of economic significance (eg sulphur for acid mine drainage characterisation). No deleterious elements have been estimated. For the majority of drillholes only copper was analysed.
· In the case of block model interpolation, the block size in relation to the average sample spacing and the search employed. The parent block size is 25 m E by 25 mN by 5.0 m RL. Sub blocking of 1mE by 1mN by 1mRL was required to honour wireframe boundaries of the historic underground workings.
Sub blocks used parent block's grade. Drilling is typically on 50m spaced sections with drillholes on sections variably spaced 10m to 60m.
· Any assumptions behind modelling of selective mining units. The selective mining unit reflects ISR as the proposed extractive technique.
· Any assumptions about correlation between variables. No correlation between variables assumptions is made.
· Description of how the geological interpretation was used to control the resource estimates. Geological logs were used to map out the extents of copper oxides, secondary and primary copper sulphides which were validated against Hylogger results and core
inspections undertaken by Terramin. Surfaces generated included; base of copper oxides, top and base of secondary copper sulphides and top of primary copper sulphides.
Estimation and modelling techniques (continued) · Discussion of basis for using or not using grade cutting or capping. No top cuts were applied. This was considered appropriate as all copper grades of the 2m composites were below the average historic production grade of 19% copper. The maximum assay from the oxide and secondary sulphide portions of the Resource were respectively 6.3% and 17.7% copper.
· The process of validation, the checking process used, the comparison of model data to drill hole data, and use of reconciliation data if available. Various visual and statistical checks were undertaken to validate modelling and grade interpolation. The global results are comparable with the reported OK models with
localised differences as expected.
Moisture · Whether the tonnages are estimated on a dry basis or with natural moisture, and the method of determination of the moisture content. The Mineral Resource estimate is based upon dry tonnages. Moisture content has not been included.
Cut-off parameters · The basis of the adopted cut-off grade(s) or quality parameters applied. A cut-off of 0.05% total copper for oxide and transitional is industry standard for ISR of copper projects. Both Excelsior Mining Corp and Cirus Resources Ltd both use a resource cut-off of 0.05% copper in their economic studies for their respective Gunnison Copper Project and Florence Copper Project located in Arizona, USA.
Mining factors or assumptions · Assumptions made regarding possible mining methods, minimum mining dimensions and internal (or, if applicable, external) mining dilution. It is always necessary as The proposed use of the ISR method to extract copper from oxide and secondary sulphide copper mineralization was chosen based on several criteria including: the majority of the ore body sitting below the water table; the fractured nature of the host rock providing transmissivity for fluids through the preferentially mineralized fracture systems; the potential amenability of the mineral species to the leaching and recovery process; the relatively low visual and environmental impact of the ISR method (no bulk movement of rock, no open cut pits or waste dumps, little noise or dust pollution) given the proximity of the orebody to the local population.
part of the process of determining reasonable prospects for eventual economic extraction to consider potential mining methods, but the assumptions made regarding mining
methods and parameters when estimating Mineral Resources may not always be rigorous. Where this is the case, this should be reported with an explanation of the basis of
the mining assumptions made.
Metallurgical factors or assumptions · The basis for assumptions or predictions regarding metallurgical amenability. It is always necessary as part of the process of determining reasonable prospects for While historic work has shown the mineral species to be targeted are amenable to leaching by a number of lixiviant systems, detailed metallurgical test work has not been completed at this stage.
eventual economic extraction to consider potential metallurgical methods, but the assumptions regarding metallurgical treatment processes and parameters made when
reporting Mineral Resources may not always be rigorous. Where this is the case, this should be reported with an explanation of the basis of the metallurgical assumptions
made.
Environmental factors or assumptions · Assumptions made regarding possible waste and process residue disposal options. It is always necessary as part of the process of determining reasonable prospects ISR allows the extraction of minerals with little physical disturbance to the environment. Since there is no physical movement of rock, there are no open cut pits, shafts or dumps to manage on surface. ISR is a closed loop system that generates much smaller volumes of mining and hydrometallurgical effluents that require management than conventional operations. While little current environmental work has been carried out on the project to date, it is assumed that waste will be minimal and will be disposed of at an EPA licenced facility.
for eventual economic extraction to consider the potential environmental impacts of the mining and processing operation. While at this stage the determination of
potential environmental impacts, particularly for a greenfields project, may not always be well advanced, the status of early consideration of these potential
environmental impacts should be reported. Where these aspects have not been considered this should be reported with an explanation of the environmental assumptions made.
Bulk density · Whether assumed or determined. If assumed, the basis for the assumptions. If determined, the method used, whether wet or dry, the frequency of the measurements, Historic density measurements were considered inappropriate as they did not make allowances for porosity of the rock. ECR and Terramin collected 202 new density measurements from 19 drillholes using a modified Archimedes method. Previous Resource estimates used an averaged density. was between and BHS and Northland used a density of 2.4 t/m3 and ACC and Stuart Minerals 2.0 t/m3. While the average interpolated density for the 2018 Mineral Resource estimate is 1.84 t/m3.
the nature, size and representativeness of the samples.
· The bulk density for bulk material must have been measured by methods that adequately account for void spaces (vugs, porosity, etc), moisture and differences between rock and alteration zones within the deposit. The modified Archimedes method is considered an appropriate method as it allows for water absorption, there was no slaking of the samples and no vugs were present.
· Discuss assumptions for bulk density estimates used in the evaluation process of the different materials. Bulk density was modelled using the same domains and search parameters used for the copper mineralisation. There is slight negative correlation with copper grade,
presumed due to increased kaolinization of the metasediments..
Classification · The basis for the classification of the Mineral Resources into varying confidence categories. The whole Kapunda Mineral Resource has been classified as Inferred. It is the view of the Competent Person that additional hydrological studies and leaching tests are required before any portion of the Mineral Resource can be classified at a higher confidence category than Inferred.
· Whether appropriate account has been taken of all relevant factors (ie relative confidence in tonnage/grade estimations, reliability of input data, confidence in continuity of geology and metal values, quality, quantity and distribution of the data). Historic data input is well documented and considered reliable.
Within the Resource the distribution of data and continuity is good.
· Whether the result appropriately reflects the Competent Person's view of the deposit. The result appropriately reflects the Competent Person's view of the deposit.
Audits or reviews · The results of any audits or reviews of Mineral Resource estimates. The 2018 Mineral Resource Estimate has been reviewed Terramin Australia.
Discussion of relative accuracy/ confidence · Where appropriate a statement of the relative accuracy and confidence level in the Mineral Resource estimate using an approach or procedure deemed appropriate by This Kapunda Mineral Resource estimate relates to copper oxide and secondary copper sulphide mineralisation within 100m of surface. The Mineral Resource estimate is considered robust and representative. This model is intended only for use in aiding scoping study investigations into the use if ISR. The Mineral Resource estimate has been classified in accordance with the JORC Code, 2012 Edition using a qualitative approach. All factors that have been considered have been sufficiently documented in Section 1 and Section 3 of this Table.
the Competent Person. For example, the application of statistical or geostatistical procedures to quantify the relative accuracy of the resource within stated confidence
limits, or, if such an approach is not deemed appropriate, a qualitative discussion of the factors that could affect the relative accuracy and confidence of the estimate.
· The statement should specify whether it relates to global or local estimates, and, if local, state the relevant tonnages, which should be relevant to technical and economic evaluation. Documentation should include assumptions made and the procedures used. The Kapunda Mineral Resource estimate relates to the copper oxide and secondary copper sulphide mineralisation where it is likely to have local variability. The global
assessment is more of a reflection of the average tonnes and grade estimate.
· These statements of relative accuracy and confidence of the estimate should be compared with production data, where available. Historic production data is not relevant for the proposed ISR extraction method as the ISR method will target the low grade halo to the historically mined mineralisation.
Mining of the high grade supergene from 1844 to 1866, largely from underground produced 13,500t of copper from 68,000t of ore at an average grade of 19.8% copper. From
1867 to 1878 approximately 300,000t of tailings, waste rock and low grade copper mineralisation mined from open cuts were leached to produce 1,600t of copper at an
average grade of 0.5%.
· The statement should specify whether it relates to global or local
estimates, and, if local, state the relevant tonnages, which should be
relevant to technical and economic evaluation. Documentation should include
assumptions made and the procedures used.
The Kapunda Mineral Resource estimate relates to the copper oxide and
secondary copper sulphide mineralisation where it is likely to have local
variability. The global assessment is more of a reflection of the average
tonnes and grade estimate.
· These statements of relative accuracy and confidence of the estimate
should be compared with production data, where available.
Historic production data is not relevant for the proposed ISR extraction
method as the ISR method will target the low grade halo to the historically
mined mineralisation. Mining of the high grade supergene from 1844 to 1866,
largely from underground produced 13,500t of copper from 68,000t of ore at an
average grade of 19.8% copper. From 1867 to 1878 approximately 300,000t of
tailings, waste rock and low grade copper mineralisation mined from open cuts
were leached to produce 1,600t of copper at an average grade of 0.5%.
This information is provided by RNS
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