SRG Graphite reports on metallurgical and expandable graphite test results
Friday, Mar 16, 2018
SRG Graphite Inc. has announced progress in the development of its mineral processing flowsheet designed in conjunction with DRA Americas and SGS Canada.  Additionally, the Company has received positive testwork results on the expandable properties of its graphite flakes from the Lola deposit.

The key result highlights are as follows:

  • Preliminary testwork suggests wet scrubbing as an alternative to traditional grinding is possible, which would reduce capital and operating costs while promoting flake size preservation.
  • Ongoing testwork suggests the developed flowsheet would allow for 95%-98% Cg concentrate to be produced over all size fractions.
  • Performed expandability testwork on +50mesh and +80mesh graphite concentrate obtained 350ml/g and 300ml/g, respectively, well over industry requirements.

Scrubbing Testwork

A first round of testwork is ongoing at SGS Canada Lakefield, with focus on the grinding method, flotation and flowsheet development. SGS Canada conducted positive preliminary testwork, using rotary scrubbing for mineral size reduction and graphite liberation. These results support the hypothesis that, for SRG Graphite’s weathered mineralized material, wet scrubbing alone, instead of the conventional primary grinding, is sufficient to produce the particle size required and ensure graphite liberation for flotation. The wet scrubbing method promotes graphite flake size preservation during mineral size reduction.

“The Installation of rotary scrubbing circuit presents a great opportunity for the reduction in capital and operating cost, as rotary scrubbing equipment is typically less expensive and consumes less electric power compared to conventional (SAG, rod or ball mill) grinding circuit employed for the same feed rate and processing duty,” said Volodymyr Liskovych, P.Eng. Senior Process Engineer, DRA.

Flowsheet Refinement

In addition to the ongoing testwork for the Company’s preliminary economic assessment, SGS processed a 120kg bulk sample of material from the Lola deposit using its latest flowsheet. The resulting grade concentrate is between 94.8% Cg and 97.9% Cg depending on the size fraction. Purity of 96.6% Cg was obtained for the -100mesh concentrate, and 97.9% Cg was obtained for the +50mesh. Jumbo flakes alone (+50mesh) accounted for 39% of the total concentrate produced.

“The ongoing testwork continues to demonstrate a simple flotation flowsheet applied to SRG Graphite’s ore produces high purity graphite concentrate with a significant amount of large and jumbo flake fractions,” says Russell McCarley, Senior Metallurgist at SGS Canada.

Graphite Expandability Testing

In addition to flowsheet development, the Company has tested its graphite flakes with specialized German graphite laboratory, ProGraphite, for expandability properties. ProGraphite performed expandability testwork on +50mesh and +80mesh graphite concentrate and obtained 350ml/g and 300ml/g respectively using an industry standard method for expandability. Sulphuric acid (H2SO4) acted as acid and donor of the intercalation molecules, while potassium permanganate (KMnO4) acted as oxidizing media to start the intercalation.

“To our knowledge, graphite flakes treated with this method typically require ratios higher than 250ml/g and 200ml/g for the +50mesh and +80mesh respectively, to be suitable for expandable graphite markets. The coarse nature of SRG Graphite’s flakes along with the results obtained during testing, makes this market particularly interesting for the Company,” Christoph Frey, Managing Director at ProGraphite GmbH said.

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