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Kachi project: drilling confirms presence of lithium brine

Published by , Assistant Editor
Global Mining Review,

Sydney-based lithium exploration and project development company Lake Resources NL (Lake Resources), which is predominantly focused on activities in Argentina, has reported its drilling results and ongoing exploration activities at its 100%-owned Kachi Lithium Brine Project in Catamarca Province.

The latest results demonstrate that lithium brine is present in numerous horizons from near surface to at least 400 m depth in drill holes spaced 11 km apart. Drilling also confirms Kachi is a very large-scale covered salt lake over an area of around 25 x 15 km (375 km2).

Lake has been conducting two concurrent phases of drilling operations:

  1. Resource exploration drilling utilising a diamond drill rig to collect drill cores for porosity assessment and to obtain brine samples for resource estimation.
  2. Production well drilling using rotary drill rigs for additional resource estimation data and construction of wells for test pumping purposes.

Lake Resource’s Managing Director, Steve Promnitz, commented: “The significant scale of the Kachi basin is evident. We believe that there is a covered salt lake with an estimated area over 25 x 15 km, hosting a very large brine body in sandy sediments with good permeability and low impurities. Drilling has intersected multiple brine aquifers. The higher lithium values with a low Mg/Li ratio in hole003 area positive discovery and indicate good potential for future positive results. Three drill rigs are on site in the expanded drill programme to accelerate exploration to produce a resource statement.”

Resource Drilling

The Kachi Lithium Brine Project in Catamarca province (Argentina) covers over 50 000 ha of mining leases owned 100% by Lake’s Argentine subsidiary, Morena del Valle Minerals SA. According to the company, these are held over the centre of the known Kachi salt lake in the deepest part of the basin. Surface sampling has revealed positive lithium results in conductive brines, which are being quantified through the drilling programme and geophysics. The current status of resource diamond drilling works comprises the completion of four diamond drill holes, with the receipt of analytical results from brine samples from the first three drill-holes. Three rotary wells have also been drilled to date with more underway. Completed diamond drill holes were progressively drilled deeper as drilling knowledge has been gained. Within the lake, variable lithologies have been intersected which are dominated by sandy sediments. Samples have been collected for porosity measurements that will be undertaken by a laboratory in the US.

Once completed, the porosity data will be used together with the systematic brine analyses from the drilling samples to produce a resource estimate in accordance with the JORC reporting code. Analytical results for lithium to date have been highest in drill-hole PP2-DV-003. Brine samples in this hole display encouraging conductivities and densities with a favourable Li/Mg ratio of 4.3. The diamond drilling intersected thick intervals of intercalated sands, gravels, sandy clays and clay horizons. The predominant litho-type of lake sediments is sand-dominant, and poorly consolidated, with relatively low core recoveries in sandy material.

The deepest drilling to date at 402 m has been undertaken in the south of the project area in diamond drill hole PP2 at site JV006 Here, approximately 300 m of almost continuous, predominantly sandy sediments have been intersected as well as two ignimbrites. An ignimbritic breccia was encountered below 300 m, underlain by a sedimentary conglomerate containing brines with encouraging densities and conductivities and iron staining which suggests secondary permeability features. The seismic geophysical program identified the ignimbritic breccia horizon which shows considerable extent in the basin.

Brine Chemistry Brines with high conductivity and density (1.18 - 1.22 g/cm3) have been intersected in thick sandy and gravelly aquifers, with the best results to date 308 mg/L after 27 hours of airlifting from 200 m depth in hole PB1-JV003. A number of samples are pending from greater depths to 400 m, where the brine has promising elevated conductivities and densities. Pump testing will occur in the near future as the rotary rig completes replication of the diamond drilling in larger diameter holes, allowing the installation of test production wells. Regular updates will be provided in future as drilling progresses. To date the lithium brines analysed show positive chemistry with low combined impurities (boron, sulfate, calcium, magnesium, iron). Brines pending analysis from deeper levels (350 – 400 m) in JV006 also show high density (1.2 g/cm3). Deeper horizons are being targeted to locate higher grades and extend the potential size of the brine mineralisation. The suggested size of the brine body has made the company contemplate further drilling rigs to accelerate the resource statement.

Production Well Drilling

The company has recently completed three rotary drill-holes. One of which will be used as an aquifer test well to better understand hydraulic properties. This first production well is located at site JV006 in the south, and diamond drill-holes at this site will act as monitoring wells. The production well is installed with 6-in. PVC casing and screens in the hole drilled at a 9.5-in. dia. A rotary drill hole was also drilled at JV003 in the west, to a depth of 242 m (PP2-DV-003). Brine in the hole was air lifted which returned a lithium grade of 308 mg/L lithium following a period of 27 hours, with an average Mg/Li ratio of 4.3. These grades are significantly higher than those recorded from shallower levels at the same location, and the airlift sample at 30 minutes is interpreted to include contributions from shallower levels.

A geophysical seismic survey is currently being undertaken using passive seismic techniques, with the aim of developing an understanding of basin geometry and thickness of the sediments hosting brine.

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