Mawson Reports Excellent Metallurgical Liberation Of Both Gold And Cobalt From Rajapalot, Finland
Wednesday, September 11th, 2019
Mawson Resources Limited (“Mawson”) or (the “Company”) (TSX:MAW) (Frankfurt:MXR) (PINKSHEETS: MWSNF) reports on gold and cobalt liberation studies from five composite drill hole samples from the Raja and Palokas inferred mineral resource project areas.
The qualitative study aimed to liberate and concentrate gold and cobalt minerals via enhanced gravity recovery. Concentrates were subsequently analyzed by Mineral Liberation Analysis to establish the geochemical, textural and mineralogical variability within mineralized domains with a view to establish a viable metallurgical flow sheet. This is the first liberation study for cobalt from the project as well as the first project-wide liberation work for gold.
- Greater than 90% of gold and cobaltite were liberated and concentrated via enhanced gravity recovery into heavy concentrates, with only moderate grinding, indicating that mineralization is amenable to low-impact and energy efficient gravity pre-concentration;
- Gold is predominantly in the form of native gold and occurs as single coarse irregular shaped grains (95% of mass);
- Cobaltite is the dominant cobalt mineral. The high density and coarse grainsize of the cobaltite make it an ideal candidate for gravitational separation in a future process flowsheet;
Mr. Michael Hudson, CEO states: “The first stage of any metallurgical study is to assess the mineral liberation characteristics of the target minerals (gold and cobalt) so that processing methods to separate them from waste minerals can be designed. These initial qualitative results are very encouraging, and indicate native gold and cobaltite are amenable to low-impact and energy efficient liberation followed by gravity pre-concentration. Work under the BATCircle research program continues for the Rajapalot project with batch flotation and leach tests planned next.”
Five samples, one from Palokas and four from the Raja prospect, were selected based on representative gold and cobalt grade and host rock composition for qualitative mineral liberation test work. Qualitative liberation of gold and cobaltite into gravity concentrates was high, exceeding 90 per cent when ground to a median grain size of 50 micron (“µm”).
Simple mineralogy and the coarse grain size of gold and cobaltite support the liberation results. In the gravity concentrates, native gold occurs predominantly as single coarse irregular shape grains (95% of mass) and fine inclusions in other minerals (5% of mass). Gold forms both coarse (up to 365µm) and fine irregular grains. Analysis of the gold indicates >95% pure gold grains dominate with only a few recorded electrum grains amongst the 503,000 total grains of all mineral species counted for the study. Approximately 22,500 individual gold grains were counted in the heavy concentrate versus only 690 electrum grains matching the typical gold to silver ratios observed in bulk rock samples. Gold and cobalt grain sizes in the five samples are generally uniform. The gold results are encouraging with grain sizes at the at the 80th percentile, gold and cobalt grains in the heavy concentrates across the 5 samples averaged 62 microns and 67 microns respectively. Fine gold grains are numerous, but by volume make up less than 5 volume percent of the samples. Cobalt grain size also shows a positive correlation with cobalt grade.
Previously, a single campaign of mineral processing and metallurgical testing was conducted by SGS Minerals UK in late 2014. This campaign was limited to the recovery of gold from the Palokas resource area. Testwork was conducted prior to the discovery of the Raja deposit or inclusion of cobalt as a potentially economic metal. The 2014 work demonstrated gold recovery is potentially amenable to conventional industry methods via a flowsheet that includes crushing and grinding, gravity recovery for gold and cobalt, and cyanide leaching with gold recovery via a carbon-in-pulp circuit for production of onsite gold doré.Gold extraction results of between 95% and 99% (average 97%) were obtained by a combination of gravity separation and conventional cyanidation. Gravity extraction from the four composites responded well with 26-48% gold extraction. Leaching was performed on the pulverised and blended tailings from the three size fractions after gravity recovery.The new gold results reported here from Raja and Palokas support this earlier work.
Cobaltite (CoAsS) is by far the most abundant cobalt mineral recovered from the five samples with minor cobalt pentlandite observed. The high density compared to the light silicate gangue and coarse grain size of the cobaltite make it an ideal candidate for gravity separation, and this work strongly supports that hypothesis. The mineral linnaeite (CoCo2S4) is recorded from other studies at Raja (Alan R Butcher, GTK pers. comm.), but was not observed in this program.
The work was completed by the Mintec Outokumpu mineralogical laboratory of the Geological Survey of Finland (“GTK”) under collaborative R&D funding provided by the BATCircle research project. As part of a broader program, Mawson and BATCircle will invest €500,000 (CAD$756k) on a 50:50 basis to conduct advanced exploration and metallurgical studies on the Rajapalot gold-cobalt project. The BATCircle research project was founded under the leadership of Aalto University to coordinate research on the battery metal circular economy from exploration to recycling. BATCircle includes 22 companies, four universities, two research institutes and two cities. The two year project has a total budget of over €20 million. The goal of the BATCircle project is to enable the creation of a market of least €5 billion in Finland.http://www.mawsonresources.com