Tanzania – The graphite from ASX-listed junior Magnis Resources’ Nachu graphite project in Tanzania is demonstrating very good crystal properties in the ore and the products derived from it, attaining high specifications in a range of applications.
With natural graphite, the quality of the flake in ore is an important determinant in the quality of products generated from it, a quality inherent in Nuchu’s graphite.
With the granting of a Special Mining Licence (SML) for the Nachu project in September, Magnis has ramped up its engagement with potential end users of both natural and synthetic graphite to:
- demonstrate the versatility of the natural graphite flake from Nachu for both traditional and emerging technology applications;
- scope developments in the graphite market to target premium priced products that can be supplied in a more sustainable and cost effective manner; and
- ensure that future processing at the mine site achieves maximum flexibility with the smallest environmental footprint and lowest cost.
“The quality of the natural graphite flake from Nachu continues to demonstrate its versatility across a range of applications. Importantly, high specifications were achieved in products generated using cost effective processes with a decreased environmental footprint. With the recent granting of the SML for Nachu, it is notable that the flotation process selected for detail design has not changed. Magnis is therefore proceeding as planned with the engineering design for the Nachu project,” Magnis CEO Dr Frank Houllis says.
The metallurgical programme for generating samples provided to end users has primarily focused on the selected flotation process consisting of one rougher flotation stage followed by three cleaner flotation stages.
When processing the composite sample derived from a wide cross section of drill holes, graphite concentrates at >98% TGC are now being produced with the +180 microns fraction regularly achieving grades in the order of 99.2% TGC. Characterisation of the flotation product according to the various sizes of graphite in the concentrate revealed highly crystalline graphite flake. In particular, X-ray Diffraction of the +300 and +180 micron products, derived d002 values of <3.35.
Good crystal properties is an important prerequisite in many applications, including emerging technology applications.
In testing for some graphite applications, chemical treatment via a caustic bake (300°C) acid leach process with no hydrofluoric acid (HF) or hydrochloric acid (HCl) was applied to the flotation concentrate product. The chemically purified graphite generated measured 99.8% TGC and expansion of the +300 and +180 micron products resulted in respective expansion weights of 2.3 g/L and 4.6 g/L.
Whilst this demonstrates the ability to make low halide content expanded graphite from Nachu, there is further work at hand at decreasing the environmental footprint of the purification step. Nevertheless, the caustic bake/acid leach process uses relatively benign chemicals and produces wastes that are readily treated in an environmentally acceptable manner.
Metallurgical development with end user engagement is an ongoing process aimed at ensuring future acceptance of Nachu graphite and the optimum performance in terms of product specification, cost and environmental footprint. Such work is being carried out in the confines of the existing flotation process to ensure mine development is not impacted.
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