- Preliminary metallurgical test work confirms leachability of lithium using sulphuric acid.
- Metallurgical recoveries of up to 95% Li were achieved within a 7 hour period.
- Recovery of lithium usingsulphuric acid is commonly used by other clay hosted lithium projects.
- Following this proof of concept, optimisation of metallurgical test work has commenced.
Hawkstone Mining Limited (ASX:HWK) (Hawkstone or the Company) is pleased to announce the results of the preliminary metallurgical test work on limited number of core samples from the Big Sandy Lithium Project (Big Sandy) located in Arizona, USA. This program follows the successful maiden drilling program and was purely designed as a proof of concept that the lithium could be extracted from the Big Sandy fresh material through the use of sulphuric acid as a metallurgical process. This program proved highly successful, as samples recorded lithium recoveries of between 85% to 97% during a maximum time period of 24 hours. Following the success of this initial program, work has now commenced to further optimise these results on a wider range of samples with the aim of reducing acid consumption and leaching time. This metallurgical test work was completed by independent consultants, Kappes Cassiday & Associates in Reno, Nevada.
Mr Paul Lloyd, the Managing Director commented: “In less than two months since completing the acquisition of Big Sandy we have now both confirmed there is significant lithium mineralisation throughout the project, and the lithium can be successfully extracted using a known and proven metallurgical process. Pleasingly both the recovery times and high recoveries, are considered excellent in comparison to other projects. Further metallurgical test work to optimise these results is underway. Whilst the application for the second drill program has been submitted with the aim to recommence drilling during early in 2019.”
The results from the preliminary leach tests demonstrated high lithium extractions using sulphuric acid. These preliminary results represent the first metallurgical work undertaken on Big Sandy fresh material and will be continue to be optimised in future rounds of test work.
Table 1 – Leach Test Results, Ambient Temperature Minus 1.7 millimetre Material
|ACID LEACH PARAMETERS||LEACH RESULTS
|Ambient Temperature Acid Leach Testing Minus 1.7 millimetre Material
Acid leach tests were conducted on minus 1.7 millimetre crushed material and minus 0.150 millimetre pulverized material at both ambient and elevated temperatures. The lithium extractions and acid consumptions were similar for both sets of tests. In these tests, no significant benefit was observed from pulverizing the crushed material. Ongoing metallurgical testing has commenced to optimise acid consumption. The new test work will include the following: • Screen analyses – wet screen analysis with a dilute acid solution and assays by size fraction. This should indicate the potential for scalping acid consumers and will serve as the basis for the target crush sizes in subsequent tests. • Acid scrub leach – scalp coarse particles at a target size (3 different target sizes) and leach the undersize. This testing is to confirm the potential benefits determined in the screen analysis stage. • Coarse crush leach – whole ore leach at a crush size larger than 1.7 mm (target size based on results from screen analysis). This testing is to determine the leach kinetics and acid consumptions at a coarser crush size than previously tested. These tests should indicate the potential for reducing reagent consumption while maintaining high lithium extraction in the leach processing.
COMPETENT PERSONS STATEMENT The information in this report that relates to exploration results is based on and fairly represents information compiled by Mr Greg Smith, a Competent Person whom is a Member of the Australasian Institute of Mining and Metallurgy. Mr Smith is the Company’s Chief Technical Officer and holds securities in the Company. Mr Smith has sufficient experience that is relevant to the style of mineralisation and type of deposit under consideration and to the activity being undertaken 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 Smith consents to the inclusion in the report of the matters based on his information in the form and context in which it appears.