Cypress Confirms Leach Results for Clayton Valley Lithium Project in Nevada - Seite 2

Laboratory Test Work

The Company is continuing laboratory work to determine the solubility of the lithium and other mineral constituents within the claystone. The Company reported at the time that a portion of the lithium is water soluble from simple assay-level tests. Bench-scale testing began in August 2017, when representative samples of oxidized and reduced material from hole DCH-05 were delivered to SGS in Lakefield, Ontario. The primary observation from these tests is the lithium in the subsurface material, at least from DCH-05 core, is almost totally insoluble in water. This contradicts the previously reported tests, which only utilized surface sample material, and suggests the water-soluble lithium occurs as a product of surficial weathering.

Further tests were completed at SGS using various acids and conditions, with the best results occurring in sulfuric acid. In these tests, extractions of 74% were achieved in both the oxidized and reduced samples. These tests used the following conditions, ground to minus-10 mesh, leached for 4 hours at 10% solids in 5% sulfuric acid and heated to 80°C. These extractions were achieved with relatively low acid additions, measured at 140 kg to 170 kg of sulfuric acid per tonne of material, and clearly contrast with the low extractions and high acid consumptions seen in hectorite-bearing claystone deposits.

Present Results

Further tests were conducted at SGS on the core from DCH-05. Following the observation where temperature set to 80°C showed a positive affect and increased the solubility of lithium significantly, subsequent tests were done with the temperature reduced to 50°C and acid concentration increased to 10%. These changes produced a mixed result, reducing the extraction in the oxidized sample to 67% (test OL-07), while increasing the extraction in the reduced sample to 80% (test RL-11). The results are consistent with the previous tests (OL-06 and RL-06), confirming the solubility of the lithium with sulfuric acid for DCH-05 core, and demonstrating the opportunity to improve extractions by adjusting leach conditions. An additional test was done on the reduced material to generate a time-extraction curve, shown below, which shows dissolution of the lithium is relatively fast, reaching 50% in the first hour, and may continue to increase beyond 4 hours.