Redevelopment Study

2018 Redevelopment Study

The extensive redevelopment study was undertaken over a two year period.  The study confirmed the robust technical and economic feasibility of the project.  The study was undertaken on the existing mineral resource which only covers 6 km of the known 27 km magnetic anomaly.  With an initial mine life of 27 years and a A$127 million capital cost, the project will deliver 7,750 tpa of vanadium pentoxide (V2O5) and annual underlying earnings of between A$50 and A$60 million based on a conservative future pricing assumption.

Key outcomes of the study are summarised in the table below.

Redevelopment Study Highlights 1

Life of mine

27 years

Average annual production

7,750t V2O5

LOM revenue

A$4.6 billion

Total capital expenditure

A$127million

1 Estimated to +/-25%

Mine Design

Mining will be undertaken using traditional load and haul equipment operating on day shift only.  An extremely low life of mine (LOM) strip ratio of 0.9 t waste per 1 t of ore is achieved by the robust and flexible design of the crushing, milling and beneficiation (CMB) circuit which enables effective processing of both the massive magnetite lenses and the disseminated magnetite hosted in fresh and weathered gabbro material.

The LOM mining inventory of 90 Mt includes no inferred mineral resource.


Metallurgical Test Work and Process Design

Preliminary metallurgical test programs were undertaken on existing ROM stockpile material and costean samples taken from the existing pit floor.  This program developed a new understanding of the drivers of magnetic recovery and concentrate grade from the various ore types.  These new recovery and concentrate grade drivers enabled the development of new metallurgical algorithms for the deposit.

The redevelopment study focused on further developing these metallurgical algorithms using composite samples derived from PQ diamond drill holes undertaken over a 5 km strike length.  A total of 21 spatial variability composite samples consisting of a mixture of oxide, transitional and fresh ore sources along with two master composite samples (oxidised and fresh ore) were constructed from the diamond drill core resulting in a total sample mass of 3,770 kg.

In addition, a total of 29 separate sections of whole core were provided for physical and comminution test work.  The work program included:

  • In-situ density measurement;
  • Uniaxial Compressive Strength (UCS);
  • Crushing Work Index;
  • Rod Mill Work Index;
  • Ball Mill Work Index;
  • Abrasion Index; and
  • JK Tech DWi A, b and Ta parameters (SMC test).

The samples underwent a range of grinding and magnetic separation tests to develop the optimum flowsheet design.  This design was tested against all the variability composite samples to ensure its suitability for all ore sources.  Mineralogical analysis of the products indicated that fresh ore recovery is exceptional with only low intensity magnetic separation (LIMS) required. The more oxidised materials require the application of medium intensity magnetic separation (MIMS) to ensure suitable recovery of weathered magnetic particles.

Application of regrind to produce a concentrate of P80 90 um was found to consistently produce a final concentrate with <2.5% SiO2, a key outcome required to achieve high salt roast recoveries in the roasting process.  Test work undertaken on magnetic concentrates produced from both fresh and oxidised ores yielded similar V2O5 recovery performance with conversions ranging from 84% to 92%.

The extensive flowsheet development test work program outcomes were combined with operating performance data and working knowledge from the historical operations to develop a robust process flowsheet.


New Crushing, Milling and Beneficiation (CMB) Flowsheet

The new flowsheet significantly simplifies operations from the existing plant and leverages off the performance and learnings from the Xstrata operating design from 1999 to 2003.

Other significant changes identified in the study include a switch to producing V2O5 flake rather than ferrovanadium (FeV) and de-bottlenecking activities around the roasting kiln and associated infrastructure.  These changes will add significantly to the operability and overall technical success of the project.


Windimurra Process Flow Diagram

Capital Costs

The capital costs for the redevelopment of the project were estimated to a +25%/-15% level using a FX rate of 1 AUD = 0.75 USD and totalled A$127 million.  A summary of the capital cost requirements is presented below.