Combined Fourth Annual Report and Final Surrender Report GR427 Florina Project for the period 30 July 2018 to 29 July 2019

Abstract

The Florina Potassium-Phosphate Project is based on the Ordovician Florina Formation in the Daly River Basin, which contains glauconite-rich sandstones. Glauconite is a potential source of potassium fertiliser with phosphate credits. Florina Formation consists of two glauconitic sandstone units sandwiched between dolostones. Two cored PQ holes drilled into the lower sandstone at localities 5 km apart, define a 19-meter thick glauconite rich unit (GRU) at the top of the lower sandstone, for which logs and photographs are available. Drill cores were lost in transit to the metallurgical laboratory, so no mineralogical, geochemical or geotechnical information is available. Detailed mapping shows the GRU is a gently undulating flat-lying unit outcropping over 102 km under shallow regolith in the middle reaches of Yujullowan Creek on EL 30603. The GRU presents an exploration target of 400Mt at a grade of 25-35% glauconite. A concentrate of grind size 106 - 280 micrometre can be achieved by WHIMS, although a cleaner circuit is required as well as a rougher and scavenger. The GRU glauconite is geologically unique in that most grains contain abundant inclusions of apatite (phosphorite) at the micron scale. Concentrate has 7.5 - 9.5% K2O and 2.65% P2O5. Glauconite can be activated in a proprietary flash reactor such that potassium and phosphorus can be leached by cold dilute acids. Activation involves de-hydroxylation which preserves grain integrity, improves specific surface area, and involves loss on ignition. Customised CA (citric acid) fertiliser analyses involving cold 5% citric acid over 28 days indicated potential for a slow-release potash fertiliser. This was confirmed by 112-day kinetic leach tests on air-activated material from the first activation campaign, which gave 45% dissolution of potassium. Follow-up 224-day kinetic leach tests were conducted on a cleaned concentrate from a second activation campaign in steam medium, at CA concentrations of 2% and 5% and different residence times. This showed 45% potassium dissolution after 224 days, which is the same extraction as the air-activated material after 112 days. This suggests better activation, as measured by better dissolution rates, is achieved with a single pass (residence time of about 7secs) in a medium of air (as distinct from steam), at the relatively low temperature of 6200C. Leachability is independent of grain size. Phosphorous dissolves early and fully. An attempt to investigate selective leaching using steam-activated glauconite was not entirely successful, indicating only low levels of potassium dissolution, and no selective leaching of iron, aluminium, calcium and magnesium. The use of activated glauconite shows promise of an innovative route to potash production, and is the subject of an Australian Patent application called Method of Producing Potash Fertiliser from a Mica Source. However it requires further optimisation of activation parameters which are independent of the nature of the Florina glauconite.