Following the exit of Exxaro in 2009 a comprehensive review of the project was undertaken and sought a revised development concept for a mine at Ranobe to supply ilmenite, rutile and zircon onto the world markets.
The primary objectives for the review were;
- Focus the initial development on the high grade area within the Ranobe deposit
- Utilise simple mining and separation methods and utilise off-the-shelf equipment
- Leverage existing infrastructure, for example the port at Toliara
- Secure the long term potential of the Toliara Sands project by proving the viability of mine development and operation
Important features of the deposit that deliver significant advantages compared to many existing operations include the low slimes content in the ore (less than 5%) and the absence of barren overburden. The global mineral sands industry mines an average ore grade of 5.1% heavy mineral with an overburden strip ratio of 0.4. By contrast, the start pit at the Ranobe Mine will have an average grade of 8.1% with no overburden. The sand is also unconsolidated and ‘free digging’ enabling simple low cost mining methods.
The heavy mineral at Ranobe consists predominantly of ilmenite making up approximately 70% of the concentrate produced. The project also benefits significantly from the presence of much higher value zircon and rutile which together contribute about 8% of the heavy mineral, but around 50% of the value of the ore mined.
Dry mine and slurry to mobile concentrators
The ore volume requirements for the project mean that the deposit may be economically mined using simple dry mining. Dry mining is an inherently flexible, low cost mining method and eliminates the high capital, water and power requirements of large scale dredge mining. This mining methodology is employed in many operations world-wide, and represents a very low risk option.
Primary concentration plants will be located close to the mine site and the sand will be return to the void and the Heavy Mineral Concentrate (HMC) will be stockpiled. The plants will be based on easily relocatable designs widely employed in many Australian ilmenite mines.
Dedicated HMC Haul Road
HMC will be hauled ~40km to the north side of the Firehana River by road trains on a dedicated haul road. Tails from the Mineral Separation Plant (MSP) will be returned to the site by the road train on the return trip and disposed of in the void.
A transfer pumping station will be built on the north side of the river and the HMC will be pumped 14km via a slurry pipeline to the MSP located at the existing Toliara port.
Simple MSP located at the port
The MSP will be located at the existing Toliara port and will produce two ilmenite products and a zircon (75%) and rutile (15%) rich non-magnetic concentrate.
Test work conducted to date shows that the ilmenite consists predominantly of a product suitable for use in the TiO2 sulphate pigment process or in ilmenite smelters for the production of chloride grade slag. A smaller volume of higher value ilmenite suitable for direct chlorination for pigment or titanium metal production or as a blend feed to synthetic rutile processors should also be recovered.
The production of the concentrate eliminates the need for a zircon/rutile circuit in the MSP and simplifies the development and operation and reduces the capital required. The concentrate will be sold to processors offshore who will recover the zircon and rutile.
Export via existing Toliara port
Utilise the existing 15,000 tonne wharf capacity to load barges for deep-water transfer to 35,000 tonne ships for bulk shipments. A reef provides natural weather and swell protection allowing the barge transfers to take place in sheltered water.
Concentrate can also be exported in containers via the existing wharf which is currently under-utilised.