Bulk Metallurgical Testwork - Strong Concentration Results
- Cobalt Blue has now completed gravity and flotation testwork on an 820 kg composite sample of Thackaringa ore.
- Recovery of cobalt to the concentrate was 92%, and the mass recovery to concentrate was 17%. The cobalt recovery represents a strong result and a significant milestone in the development of the Thackaringa project.
- Recovery of cobalt was achieved with coarse crush size of 1.2 mm and gravity separation, indicating low capital and operating costs compared to fine milling and floating the entire ore.
- Cobalt Blue is pleased to announce the appointment of Dr Andrew Tong to manage COB's Feasibility Studies. Dr Tong's background is included in this release.
Pre-Feasibility Testwork Overview
The Thackaringa project is planning to mine ore from three surface deposits. The host rock (silica and feldspars) contains approximately 20% sulphides (mainly pyrite), with cobalt at 900-1000 ppm. Upgrading the ore to a sulphide concentrate is an important step to developing an economically viable project.
Diamond drill core samples were collected in late 2016 and used for testwork in the Scoping Study which was completed June 30 2017. Approximately 820 kg of the ore, representing the Railway and Pyrite Hill deposits, was composited in August 2017, and is being used to test the preferred process for the Pre-Feasibility Study (PFS). The PFS testwork program is designed to deliver 'reliable and repeatable' results at a scale 10-50 times larger than the tests used in the Scoping Study (July 12), where the 'proof-of-concept' was determined. The results will be used to conducted engineering studies and cost estimates for the PFS.
The PFS is examining the processing path shown below (also see link below):
MINE > CONCENTRATE > CALCINE > LEACH > PRODUCT RECOVERY
There are four stages to the metallurgical testwork (post mining):
A. Concentrate: Preparation of a sulphide concentrate from the ore (this market release)
B. Calcine: Calcination (thermal treatment) of the concentrate
C. Leach: Leach the calcine
D. Product Recovery
Processing - Concentrate
Ore was processed by crushing to p100 @ 1.2 mm and passed through a gravity spiral circuit. The tails were screened, with the fines subjected to froth flotation. The gravity and flotation concentrates were combined into a single concentrate. The results are summarised in link below.
The key outcomes are:
- High cobalt recovery to concentrate of 92% from the ore
- High recovery of cobalt achieved with coarse crush size of 1.2 mm and gravity separation, indicating low capital and operating costs compared to fine milling and floating the entire ore
Cobalt Blue's Feasibility Studies Manager, Dr Andrew Tong said:
"The ability to easily produce a concentrate containing 0.3-0.4% cobalt from Thackaringa ore, using predominately gravity separation, is an important first step in determining the economic viability of the project. A low-cost concentrate pathway to reduce the mass by 80%, and still retain over 90% of the cobalt, is essential to delivering a higher grade feed to the refinery. This stands in contrast to other cobalt projects where options are limited for upgrading the run-of-mine ore prior to metallurgical processing e.g. laterites."
A conceptual schematic of the commercial plant concentrate circuit is shown in the following graphic. The aim is to treat 5 MTPA of ore and produce 1 MTPA of concentrate, with a cobalt recovery of 90-95%. The concentrate step will produce a feed material containing ~0.4% cobalt, which will be forwarded to an onsite refinery for production of cobalt sulphate.
PFS testwork - looking forward
Overall COB is delighted with the concentration testwork and is looking forward to completing Calcine and Leach (Steps 2 & 3) testwork in the coming weeks. This testwork will be the subject of a separate market announcement. A schedule of the testing program is shown below, and we expect the majority of the program to be completed by the end of December 2017.
COB remains focussed on proving up the processing and economics of our unique ore. Our goal is to prove a long life mining operation capable of operating at cobalt cycle troughs, whilst generating significant margins at current market pricing.
Thackaringa Project timetable
Results to date continue to justify proceeding further along the pathway towards commercial development of the Thackaringa cobalt project. The overall company timeline is shown in link below.
The Thackaringa Cobalt Project site and potential services are shown on the following page. The site is situated close to Broken Hill, and is well connected to existing transport routes including the Barrier Highway and the Intercontinental Railway. Availability of water and power supplies further support positive project economics.
Dr Andrew Tong - Background
Andrew is a metallurgist with 15 years of experience in project development, mining and processing activities. He is formerly the CEO of Compass Resources/Northern Territories Resources (2016-2017), and is now a non-executive Director of Northern Territories Resources (2017-present). Prior to that Andrew was the CEO of Goldsmith Resources (Peru) (2014-2015), and director of Australia Gold (2010-2017). Andrew has considerable experience in projects targeting extraction of metals from complex polymetallic feeds or refractory minerals such as pyrite. He has developed and patented metallurgical processes, managed testwork programs and project studies, and is a welcome addition to the COB team.
To view tables and figures, please visit:
About Cobalt Blue Holdings Limited
Cobalt Blue Holdings Ltd (ASX:COB) is an exploration company focussed on green energy technology and a strategy of fast-tracking development of the Thackaringa Cobalt Project in New South Wales to achieve commercial production of cobalt. This strategic metal is in strong demand for new generation batteries, particularly lithium-ion batteries now widely used in clean energy systems.
COB has entered into a farm-in joint venture agreement with Broken Hill Prospecting Limited (“BPL”) in which COB seeks to acquire an initial 51% interest in the Thackaringa Cobalt Project. COB will undertake exploration and development programs on the Thackaringa Cobalt Project and, subject to the achievement of milestones, will acquire 100% of the Thackaringa Cobalt Project.
Cobalt Blue Holdings Limited