- 1st Stage metallurgical testwork results support potential for simple, low-cost processing using established technologies
- Crush and screen results demonstrate that high-grade Li-B mineralisation is coarse, dominated by the mineral searlesite and low in clay and carbonate minerals
- Next stage of testwork focussing on producing a Li-B rich searlesite concentrate to enhance the low-cost acid leach processing route
- Initial drilling program completed with 2 holes at North Basin and 3 holes at South Basin - assay result expected over the next 3-4 weeks
The metallurgical program is aimed at evaluating a simple process route involving crushing, screening and flotation followed by dilute acid leaching to liberate lithium and boron. The relatively simple process route, using established technologies, is expected to compare favourably to other sources of lithium including brine and spodumene deposits.
Key steps in the metallurgical program are to establish parameters for:
1. Crushing, screening and attrition to separate clay and reduce acid consuming carbonate minerals from Li-B rich searlesite mineralisation.
2. Flotation to further reduce carbonate minerals and produce a Li-B rich searlesite concentrate
3. Acid leaching of the Li-B searlesite concentrate to determine Li/B recoveries and acid consumption
The results being reported today relate to step 1 and show that the Li-B rich mineralisation is mainly composed of relatively coarse material (78% greater than 212 microns) and that the coarse material comprises 40-44% searlesite. The results confirm the coarse nature and low clay content of the searlesite mineralisation and indicate that the mineralisation is likely to be amenable to further concentration and acid leaching with modest acid consumption levels.
Metallurgical testwork is being undertaken by Hazen Research in Colorado, USA and SGS Minerals in Ontario, Canada. The initial results are from a sample of Li-B mineralisation collected from outcrop along the western margin of South Basin and within the Mineral Resource. The same testwork is currently being undertaken on drill core samples and results will be released as they become available.
The entire sample was crushed to 100% passing (P100) 25mm (2500 microns). A 5kg subsample was stage crushed to minus 1.7mm then dry screened at 850, 425, 212, 150, and 75 microns (µm). The results of size fraction analysis are shown in Table 1 (see the link below). Subsamples were collected from the +850, +212 and -75 micron fractions for mineralogical determination by XRD analysis and the results are shown in Table 2 (see the link below).
The results confirm the coarse nature and low clay content of the searlesite mineralisation and indicate that the mineralisation is likely to be amenable to further concentration and acid leaching with modest acid consumption levels. The ongoing program is now investigating the separation of the remaining clay via attrition (intense agitation in water) and the removal of acid-consuming carbonate minerals (calcite and dolomite) by flotation to produce a Li-B rich searlesite concentrate. The concentrate will then be subject to acid leach tests.
The initial drilling program has been completed. Two holes were drilled at North Basin and three at South Basin for a total of 1246m. Assay results are expected over the next 3 to 4 weeks.
About Rhyolite Ridge Lithium-Boron Project
Rhyolite Ridge is a lithium-boron deposit located in southern Nevada. The deposit contains a Resource of 3.4 million tonnes of lithium carbonate and 11.3 million tonnes of boric acid, making it one of the largest lithium and one of the largest boron deposits in North America. The Resource is open in most directions and is likely to increase in size with additional drilling. In addition, the North Basin hosts lithium-boron mineralisation drilled by a previous exploration company in the 1980's that is not included in the Resource.
The Resource contains a high-grade Li-B zone referred to as the Searlesite Zone and comprising 65Mt at 1.0% Li2CO3 and 9.1% H3BO3 for a total of 650,000 tonnes of lithium carbonate and 5.9 million tonnes of boric acid - sufficient material to support a 3Mtpa mining operation over 20 years.
The mineralisation is hosted within shallow, flat-lying sedimentary rocks, representing a potential third source of lithium - in addition to brine and pegmatite types. Lithium-boron mineralisation occurs with the mineral searlesite - an acid leachable sodium boro-silicate mineral.
Rhyolite Ridge is located close to existing infrastructure and is 25km west of Albermarle's Silver Peak lithium mine and 340km by paved road from the Tesla Gigafactory. It has the potential to be a strategic, long-life, low-cost and reliable source of lithium and boron. Global has the exclusive right to purchase 100% interest in the project.
To view tables and figures, please visit:
About Global Geoscience Limited
Global Geoscience Limited (ASX:GSC) is a Sydney-based mineral exploration company specialising in greenfield exploration and mineral discovery. The Company's main focus is for copper, gold and silver on its mostly 100%-owned projects in Nevada and Arizona in the United States, and Peru in South America.
Global Geoscience Limited