10th Aug 2016 08:45
10 August 2016
| AIM/ASX Code: SO4
|
SALT LAKE POTASH LIMITED Geophysics and Test Pumping Reinforce Lake Wells Potential |
Salt Lake Potash Limited (SO4 or the Company) is pleased to advise the results of a comprehensive geophysical survey at Lake Wells, as well as outstanding initial test pumping results of brine from the Lake Wells paleochannel. These results substantially enhance the potential for production of Sulphate of Potash (SOP) by brine extraction and solar evaporation at the Lake Wells Project.
· Over 350km of ground based gravity and seismic surveys have been completed, providing the first detailed geophysical model of the Lake Wells paleovalley.
· The model has mapped the deepest parts of the paleovalley (identified as the paleochannel) over approximately 100km within the Project area, the target for the paleochannel aquifer which is likely to provide the best sites for brine extraction bores.
· An aircore drill program testing the paleochannel geophysical model along the Northern fringes of the Lake has completed five holes, all of which validated the interpretation.
· Three of those holes were on the north-eastern fringe of the Lake, testing the main trunk of the modelled paleochannel and encountering substantial widths of paleochannel sands, including two with very coarse (more permeable) sands and gravels.
· A comprehensive, sustained pump test of one of the coarse sand and gravel zones confirms production bores in this part of the aquifer should sustain brine extraction rates of up to 25 litres per second (L/s), reinforcing the potential for extraction of large volumes of hypersaline brine from the paleochannel aquifer.
CEO Matt Syme commented "We are again very pleased with our exploration results at Lake Wells, with a test pumping result which we believe is one of the highest quality and most comprehensive undertaken on an Australian salt lake. The geophysical surveys and interpretation have produced a comprehensive model of Lake Wells to guide our future exploration work. As the first test pumping demonstrates, the model will allow us to find the most effective basis to extract Lake Wells' large brine resource and has already provided valuable input into the Scoping Study currently underway."
Geophysical Surveys
An extensive ground based geophysical survey was completed aimed at assessing the Lake Wells bedrock topography and generation of paleochannel aquifer drill targets. Atlas Geophysics were engaged to undertake a gravity survey using industry leading high accuracy gravimeters and position systems to measure subsurface density. A total of 46 gravity lines comprising 2,147 stations spaced 50 - 200m apart were completed. In addition, a passive seismic (Tromino) system was used to correlate a secondary geophysical interpretation tool with the gravity and provide a more robust model. A total of 11 passive seismic lines spanning 30km was completed on priority lines identified by the gravity survey.
Gravity measurements were processed and merged by Western Geophysics with available regional data. The final merged residual gravity data have been used as the basis for interpretation.
Image processing of the gravity data shows there is a semi-continuous distinct residual gravity low present along the eastern to central areas of the entire tenement area. The anomaly which is approximately 2km wide, traces a typically sinuous path, including several cut out meandering branches from the northern to southern tenement boundaries. The location and depth of the paleochannel has been interpreted by modelling gravity profiles across the structure. Modelling has been assisted and where applicable constrained by a number of aircore holes that have penetrated the Tertiary sequence to bedrock.
The geophysical modelling indicates the paleochannel has a maximum depth of approximately 125m. At these points the geometry of the model is that of a valley which is approximately 800m wide. Completed drill holes have encountered a basal aquifer comprising sand, gravel and rounded cobble sized rocks. The basal unit is up to 30m thick and limited pump testing indicates the presence of a highly permeable aquifer.
The gravity survey method has been successfully applied to mapping the Lake Wells paleochannel for over 100km within the Company's tenements.
Aircore Drilling
A truck mounted aircore drill rig from Austral Drilling was mobilised to the northern end of Lake Wells for initial exploratory drilling to test the geophysical paleochannel model. In the current campaign, five holes have been completed on either side of the Lake where the channel was interpreted to be between 101m and 125m deep.
All five holes validated the geophysical model, encountering bedrock at the predicted depth. The three holes on the northern side of the lake encountered significant widths of paleochannel sand and gravels.
In holes LWA030 and LWA033 coarse sands and gravels were encountered from 95m to up to 130m, where very substantial airlift flows of between 7 and 9L/s were measured. Water assays confirm the aquifer contains hypersaline brine of similar chemistry to other paleochannel bores drilled on lake at Lake Wells.
In both holes, the aircore rig encountered rounded to sub-angular cobbles of up to 8cm in diameter and high sub-artesian conditions.
Test pumping
A subsequent mud rotary hole adjacent to hole LWA033 was successfully cased and screened from 95m to 125m. Siltstone bedrock was encountered from 125m to end of hole at 130m.
A test pumping system from Airwell Group was mobilised to Lake Wells and installed a pump at 59m. A calibration test was completed, including pumping for 10 minutes at 20L/s and 2 minutes at 40L/s to test the sustainable flow rates for the step rate test. A step rate test was then undertaken to measure bore performance at flow rates of between 6 and 16L/s, followed by a 10 hour constant rate test to determine aquifer properties at 15L/s.
Modelling of the step rate test indicates that a pump set at 90m in this bore will be able to produce a sustained yield of up to 25L/s, substantially more than previously assumed for production from the paleochannel aquifer.
The constant rate test, has measured aquifer transmissivity of 41m2 per day, with an equivalent bulk hydraulic conductivity of 1.4m per day.
Ongoing pump testing on this hole will also provide industry leading data on aquifer boundary conditions and storage.
Ongoing Work
Having successfully validated the geophysical model, the aircore rig will now proceed to test a number of other targets along the full length of the paleochannel, in order to further understand the characteristics of the paleochannel aquifer. Where appropriate, further test pumping bores, similar to that installed adjacent to hole LWA033, will likely be installed and test pumped, to advance and refine the Lake Wells hydrogeological model.
Competent Persons Statement
The information in this report that relates to Exploration Results for Lake Wells is based on information compiled by Mr Adam Lloyd, who is a member of the Australian Institute of Geoscientists and International Association of Hydrogeology. Mr Lloyd is an employee of Salt Lake Potash Limited. Mr Lloyd has sufficient experience, which is relevant to the style of mineralisation and type of deposit under consideration and to the activity, which he is undertaking to qualify as a Competent Person as defined in the 2012 Edition of the 'Australasian Code for Reporting of Exploration Results, Mineral Resources and Ore Reserves'. Mr Lloyd consents to the inclusion in the report of the matters based on his information in the form and context in which it appears.
APPENDIX 1 - LAKE WELLS DRILLHOLE DATA
Hole_ID | Drilled Depth (m) | East | North | RL | Dip | Azimuth |
(mAHD) | ||||||
LWA030 | 107 | 518525 | 7058696 | 449 | -90 | 0 |
LWA031 | 100 | 526074 | 7040567 | 444 | -90 | 0 |
LWA032 | 101 | 523934 | 7040676 | 443 | -90 | 0 |
LWA033 | 110 | 518038 | 7055963 | 444 | -90 | 0 |
LWA034 | 126 | 527040 | 7045891 | 442 | -90 | 0 |
APPENDIX 2 - JORC TABLE ONE
Section 1: Sampling Techniques and Data
Criteria | JORC Code explanation | Commentary |
Sampling techniques | Nature and quality of sampling (eg cut channels, random chips, or specific specialised industry standard measurement tools appropriate to the minerals under investigation, such as down hole gamma sondes, or handheld XRF instruments, etc). These examples should not be taken as limiting the broad meaning of sampling. Include reference to measures taken to ensure sample representivity and the appropriate calibration of any measurement tools or systems used. Aspects of the determination of mineralisation that are Material to the Public Report. In cases where 'industry standard' work has been done this would be relatively simple (eg 'reverse circulation drilling was used to obtain 1 m samples from which 3 kg was pulverised to produce a 30 g charge for fire assay'). In other cases more explanation may be required, such as where there is coarse gold that has inherent sampling problems. Unusual commodities or mineralisation types (eg submarine nodules) may warrant disclosure of detailed information. | Geological samples were obtained at 1m intervals from the top of the open hole by sieve during mud rotary drilling and from buckets below the cyclone during aircore drilling. The mud rotary samples were logged and used to confirm the geological strata encountered are equivalent to the adjacent aircore hole, typically less than 10m away. Brine samples were obtained during aircore drilling from the cyclone when airlifting at the end of each drill rod. Airlifts were completed on minimum air and sampling took place following stabilisation of flow approximately between 2 and 10mins from start of airlift. The pump used during test pumping was an 8" Grundfos SP160-8 coupled to a Franklin 150KW motor. The flow from the bore was controlled using a variable speed drive and monitored using dual calibrated magflow meters. The test pumping methodology involved calibration testing to ensure equipment is working appropriately and to estimate sustainable step rate flow rates, individual steps were a minimum of 60 minutes' duration. The constant rate was run for 10 hrs before drawing the pumping water level down to below the level of the pump at 59m. Recovery of water levels was monitored. All data was used in the interpretation. Drawdown in the pumping bore (LWTB009) and monitoring bore (LWA033) was measured using vented data loggers coupled to a laptop to provide a live readout. The discharge line outlet at the test bore was located 150m away from the bore, no re-circulation effects were detected due to the confined nature of the aquifer. |
Drilling techniques | Drill type (eg core, reverse circulation, open-hole hammer, rotary air blast, auger, Bangka, sonic, etc) and details (eg core diameter, triple or standard tube, depth of diamond tails, face-sampling bit or other type, whether core is oriented and if so, by what method, etc). | Non-face discharge vacuum aircore drilling at 138mm diameter and conventional mud rotary drilling at diameters between 162mm and 374mm and was completed by Austral Drilling Services of Malaga, Perth. All drilling was completed using a multipurpose truck mounted Schramm 685. All holes vertical. |
Drill sample recovery | Method of recording and assessing core and chip sample recoveries and results assessed. Measures taken to maximise sample recovery and ensure representative nature of the samples. Whether a relationship exists between sample recovery and grade and whether sample bias may have occurred due to preferential loss/gain of fine/coarse material. | Geological sample recovery when aircore drilling was through the cyclone and of excellent quality. Drill rates were slowed to ensure a clean sample was produced and that contamination was minimised. Cuttings were recovered by placing a clean bucket under the cyclone for the entire metre length and then emptying out on a pre-marked grid on the edge of the drill pad. Geological sample recovery when drilling conventional mud rotary was low to moderate due to the crushing and mixing nature of the drilling method. Brine sample recovery during test pumping was relevant to the bulk chemistry of the slotted section of the production bore. Airlifts were completed on minimum air and sampling took place following stabilisation of flow approximately between 2 and 10mins from start of airlift.
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Logging | Whether core and chip samples have been geologically and geotechnically logged to a level of detail to support appropriate Mineral Resource estimation, mining studies and metallurgical studies. Whether logging is qualitative or quantitative in nature. Core (or costean, channel, etc) photography. The total length and percentage of the relevant intersections logged. | All drill holes were geologically logged qualitatively by a qualified geologist, noting in particular moisture content of sediments, lithology, colour, induration, grainsize and shape, matrix and structural observations. Where mud rotary drilling was completed logging was compared to the adjacent aircore hole to determine if geological variation occurs. Flow rate data from airlifting was logged to note water inflow zones. Mud logs were completed during mud rotary drilling to record how the muds changed composition during drilling through different formations to maintain a stable hole and optimise penetration rate. |
Sub-sampling techniques and sample preparation | If core, whether cut or sawn and whether quarter, half or all core taken. If non-core, whether riffled, tube sampled, rotary split, etc and whether sampled wet or dry. For all sample types, the nature, quality and appropriateness of the sample preparation technique. Quality control procedures adopted for all sub-sampling stages to maximise representivity of samples. Measures taken to ensure that the sampling is representative of the in situ material collected, including for instance results for field duplicate/second-half sampling. Whether sample sizes are appropriate to the grain size of the material being sampled. | Brine was sampled directly from the end of the discharge hose during test pumping or flowing water from the top of the bore casing during development, ensuring no contamination with overland flow occurred. Brine samples were obtained during aircore drilling from the cyclone when airlifting at the end of each drill rod. Sample bottles are rinsed with brine which is discarded prior to sampling. All brine samples taken in the field are split into two sub-samples: primary and duplicate. Reference samples were analysed at an approximate 1:8 ratio and sent to a separate laboratory for QA/QC. Brine samples once collected are stored in eskys on site for no more than 7 days prior to freighting to the laboratory for testing. Representative chip trays and bulk lithological samples are kept for records. |
Quality of assay data and laboratory tests | The nature, quality and appropriateness of the assaying and laboratory procedures used and whether the technique is considered partial or total. For geophysical tools, spectrometers, handheld XRF instruments, etc, the parameters used in determining the analysis including instrument make and model, reading times, calibrations factors applied and their derivation, etc. Nature of quality control procedures adopted (eg standards, blanks, duplicates, external laboratory checks) and whether acceptable levels of accuracy (ie lack of bias) and precision have been established. | Primary samples were sent to Bureau Veritas Minerals Laboratory, Perth. Brine samples were analysed using ICP-AES for K, Na, Mg, Ca, with chloride determined by Mohr titration and alkalinity determined volumetrically. Sulphate was calculated from the ICP-AES sulphur analysis. Reference standard solutions were sent to Bureau Veritas Minerals Laboratory to check accuracy. Reference standards analysis reported an average error of less than 10%. · . |
Verification of sampling and assaying | The verification of significant intersections by either independent or alternative company personnel. The use of twinned holes. Documentation of primary data, data entry procedures, data verification, data storage (physical and electronic) protocols. Discuss any adjustment to assay data. | Data entry is done in the field to minimise transposition errors. Brine assay results are received from the laboratory in digital format, these data sets are subject to the quality control described above. All laboratory results are entered in to the company's database and validation completed. Independent verification of significant intercepts was not considered warranted given the relatively consistent nature of the brine. |
Location of data points | Accuracy and quality of surveys used to locate drill holes (collar and down-hole surveys), trenches, mine workings and other locations used in Mineral Resource estimation. Specification of the grid system used. Quality and adequacy of topographic control. | Hole co-ordinates were captured using hand held GPS. Coordinates were provided in GDA 94_MGA Zone 51. Topographic control is obtained using Geoscience Australia's 3-second digital elevation product. Topographic control is not considered critical as the salt lakes are generally flat lying and the water table is taken to be the top surface of the brine resource. GNSS and gravity control stations were used to tie the survey to GDA94 and Australian Height Datum. Primary gravity control stations were established at the same location as the primary GNSS Once tied to the Australian Fundamental Gravity Network (AFGN), the gravity control stations allowed all field gravity observations to be tied to the AAGD07 gravity datum employed by Geoscience Australia |
Data spacing and distribution | Data spacing for reporting of Exploration Results. Whether the data spacing and distribution is sufficient to establish the degree of geological and grade continuity appropriate for the Mineral Resource and Ore Reserve estimation procedure(s) and classifications applied. Whether sample compositing has been applied. | Drill hole spacing is on average 4 km. The drilling is not on an exact grid due to the irregular nature of the salt lake shape, aquifer occurrence and difficulty obtaining access to some part of the salt lake.
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Orientation of data in relation to geological structure | Whether the orientation of sampling achieves unbiased sampling of possible structures and the extent to which this is known, considering the deposit type. If the relationship between the drilling orientation and the orientation of key mineralised structures is considered to have introduced a sampling bias, this should be assessed and reported if material. | All drill holes were vertical. Geological structure is considered to be flat lying.
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Sample security | The measures taken to ensure sample security. | All brine samples were marked and kept onsite before transport to the laboratory. All remaining sample and duplicates are stored in the Perth office in climate-controlled conditions. Chain of Custody system is maintained. |
Audits or reviews | The results of any audits or reviews of sampling techniques and data. | Data review is summarised in Quality of assay data, laboratory tests and Verification of sampling and assaying. No audits were undertaken. |
Section 2: Reporting of Exploration Results
Criteria | JORC Code explanation | Commentary |
Mineral tenement and land tenure status | Type, reference name/number, location and ownership including agreements or material issues with third parties such as joint ventures, partnerships, overriding royalties, native title interests, historical sites, wilderness or national park and environmental settings. The security of the tenure held at the time of reporting along with any known impediments to obtaining a licence to operate in the area.
| Tenements drilled were granted exploration licences 38/2710, 38/2821, 38/2824, 38/3055, 38/3056 and 38/3057 in Western Australia. Exploration Licenses are held by Piper Preston Pty Ltd (fully owned subsidiary of ASLP).
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Exploration done by other parties | Acknowledgment and appraisal of exploration by other parties. | No other known exploration has occurred on the Exploration Licenses. |
Geology | Deposit type, geological setting and style of mineralisation. | Salt Lake Brine Deposit |
Drill hole Information | A summary of all information material to the understanding of the exploration results including a tabulation of the following information for all Material drill holes: o easting and northing of the drill hole collar o elevation or RL (Reduced Level - elevation above sea level in metres) of the drill hole collar o dip and azimuth of the hole o down hole length and interception depth o hole length. If the exclusion of this information is justified on the basis that the information is not Material and this exclusion does not detract from the understanding of the report, the Competent Person should clearly explain why this is the case. | Test production bore drilling comprised one mud rotary drilled hole. Aircore Drilling comprised five aircore holes. Details are presented in the report.
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Data aggregation methods | In reporting Exploration Results, weighting averaging techniques, maximum and/or minimum grade truncations (eg cutting of high grades) and cut-off grades are usually Material and should be stated. Where aggregate intercepts incorporate short lengths of high grade results and longer lengths of low grade results, the procedure used for such aggregation should be stated and some typical examples of such aggregations should be shown in detail. The assumptions used for any reporting of metal equivalent values should be clearly stated. | Within the salt lake extent no low grade cut-off or high grade capping has been implemented.
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Relationship between mineralisation widths and intercept lengths | These relationships are particularly important in the reporting of Exploration Results. If the geometry of the mineralisation with respect to the drill hole angle is known, its nature should be reported. If it is not known and only the down hole lengths are reported, there should be a clear statement to this effect (eg 'down hole length, true width not known'). | The brine resource is inferred to be consistent and continuous through the full thickness of the sediments. The unit is flat lying and drill holes are vertical hence the intersected downhole depth is equivalent to the inferred thickness of mineralisation. |
Diagrams | Appropriate maps and sections (with scales) and tabulations of intercepts should be included for any significant discovery being reported These should include, but not be limited to a plan view of drill hole collar locations and appropriate sectional views. | Addressed in the announcement. |
Balanced reporting | Where comprehensive reporting of all Exploration Results is not practicable, representative reporting of both low and high grades and/or widths should be practiced to avoid misleading reporting of Exploration Results. | All results have been included. |
Other substantive exploration data | Other exploration data, if meaningful and material, should be reported including (but not limited to): geological observations; geophysical survey results; geochemical survey results; bulk samples - size and method of treatment; metallurgical test results; bulk density, groundwater, geotechnical and rock characteristics; potential deleterious or contaminating substances. | Test pumping interpretation data was corrected for brine specific gravity and analysed using the industry standard Cooper - Jacob method (Cooper, H.H. & Jacob, C.E. (1946) A generalised graphical method for evaluation formation constants and summarizing well field history. Transactions of the American Geophysical Union 27, 526-534). Gravity survey was completed by Atlas Geophysics using a Hi Target V100 GNSS receiver for accurate positioning and CG-5 Digital Automated Gravity Meter. Gravity data was gained using the contractors rapid acquisition, high accuracy UTV borne techniques. The company's own in-house reduction and QA software was used to reduce the data on a daily basis to ensure quality and integrity. All gravity meters were calibrated pre and post survey and meter drift rates were monitored daily. 3 to 5 % of the stations are repeated for quality control. Western Geophysics were engaged to manage and process the gravity survey. Processing the survey involved reducing the gravity data and integrating to the regional data to a residual anomaly which shows there is a semi-continuous distinct residual gravity low of negative 2 to 2.5 milligals present along eastern to central areas to the entire tenement area. |
Further work | The nature and scale of planned further work (eg tests for lateral extensions or depth extensions or large-scale step-out drilling). Diagrams clearly highlighting the areas of possible extensions, including the main geological interpretations and future drilling areas, provided this information is not commercially sensitive. | Exploration aircore drilling to further define the paleochannel aquifer depth and geometry. Installation of monitoring bores. Further test production bores to be constructed and test pumping completed to determine, aquifer properties, expected production rates and infrastructure design (trench and bore size and spacing). Numerical hydrogeological modelling to be completed that incorporates the results of the test pumping. The model will be the basis of the annual brine abstraction rate and mine life. |
For further information please visit www.saltlakepotash.com.au or contact:
Matthew Syme/Sam Cordin | Salt Lake Potash Limited | Tel: +61 8 9322 6322 |
Colin Aaronson/Richard Tonthat/Daniel Bush | Grant Thornton UK LLP (Nominated Adviser) | Tel: +44 (0)207 383 5100 |
Nick Tulloch/Beth McKiernan | Cenkos Securities plc (Broker) | Tel: +44 (0) 131 220 6939 |
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