Rock samples from the Gibellini project in Nevada. Image courtesy of American Vanadium.
A core drill rig operating at the Gibellini mine. Image courtesy of American Vanadium.
Bulk samples being collected for metallurgical testing. Image courtesy of American Vanadium.
Reverse circulation rig in action at the Gibellini vanadium mine. Image courtesy of American Vanadium.

The Gibellini vanadium project is an open-pit project being developed by Prophecy Development in Eureka County, Nevada, US. Spread over 6,600 acres, the project is the only large-scale, heap-leach vanadium project of its kind in North America.

A feasibility study (FS) of the project was prepared by the previous developer American Vanadium Corporation in September 2011. Prophecy is also undertaking an FS, which is anticipated to complete by the end of 2019.

Prophecy plans to start mine construction in 2021 following the completion of the environmental impact statement (EIS) and receipt of Nevada State permits. Vanadium production is anticipated to begin in the fourth quarter of 2022.

The Gibellini project is anticipated to produce 9.7Mlb of V2O5 per year through its anticipated mine life of 13.5 years.

Gibellini vanadium project location, geology, and mineralisation

The Gibellini vanadium project is a part of the Fish Creek Range and contained in an allochthonous fault wedge made of siliceous mudstone, siltstone and chert rocks of the Devonian Age Woodruff formation. They occur in the form of thin bedded shales, which are very fragile, distorted and fractured.

The mine’s geological formation comprises three layers, including an oxidised zone, transition zone (mix of oxidised and unoxidised zones) and unoxidised zone. The top layer stretching 100ft to 120ft thick has been oxidised, creating orange, pink and purple vanadium oxide minerals.

Vanadium mineralisation is mainly concentrated in a black shale transition zone, which is 175ft to 300ft-thick overlaid by grey mudstone. Oxidisation has rendered hues of yellow and orange to the shale up to a depth of 100ft.

The transition zone contains the highest grades of vanadium while the unoxidised zone hosts lower grade vanadium in comparison with the oxidised and transition zones.

Gibellini vanadium project reserves

The NI 43-101 compliant combined measured and indicated resources at the Gibellini vanadium project are estimated to be 22.95Mt, grading at 0.286% V2O5.

Vanadium mining and processing

The Gibellini project will employ conventional open-pit methods of mining, involving drilling and blasting followed by loading and hauling. The mine plan assumes production at three million short tons (Mstpa) from two open pits at Gibellini and Louie Hill.

Five pit phases were developed for the project, of which phases I, III, and IV are mined from the Gibellini deposit. The remaining II and V phases are mined from the Louie Hill deposit.

The proposed Gibellini project will utilise acid heap leaching and solvent extraction technology to recover vanadium. The mine is expected to process 3Mtpa of heap leach material. Ore will be crushed, agglomerated and cured with acid.

The cured ore will be moved to the curing pad through a radial stacker. The resultant agglomerates will be loaded from the curing pad and will rest for one week before undergoing leaching. The material will be treated with a leap solution for 90 days, following which the pregnant leap solution is forwarded to a strip circuit.

Vanadium is then recovered in the strip circuit and treated with ammonia and followed by the calcination process. The final vanadium pentoxide will be crushed and packed in drums to form purple flakes. The packaged product will be transported to a conversion company in Butler, Pennsylvania.

Infrastructure facilities

Access to the Gibellini vanadium project is through a graded gravel road extending south from US Highway 50.

The anticipated 24.9kV power supply for the Gibellini project will be supplied from a planned substation near Fish Creek Ranch.

Water supply for the project will be collected from a private ranch, located approximately 14.5km from the project, under a ten-year water lease agreement.

Contractors involved

US-based design and construction services company M3 Engineering was awarded the engineering, procurement, construction management services contract for the project.

Prophecy engaged Amec Foster Wheeler E&C Services (Wood) for updating the mineral resource and mining section of the project FS.

Prophecy and Shaanxi Huayuan Mining affiliate Northwest Nonferrous Metals Mining Group (NWME) reached a technical advisory and cooperation agreement to develop the vanadium project. NWME is also responsible for the technical design and engineering of vanadium ore processing facilities at Gibellini.

NewFields Companies was awarded the contract to undertake the permitting and EIS preparation of the project. The company is also responsible for conducting an internal assessment of the required updates to the Gibellini baseline studies as mentioned in the mine plan of operations (MPO) submitted in May 2019.

SWCA Environmental Consultants was appointed to work under the guidance of the Bureau of Land Management for the preparation of the EIS in June 2019.

SRK Consulting (US) prepared the MPO of the vanadium project.