Processing involves existing practices and equipment. A basic description of the typical processes are provided as an example:
SCREENING AND ATTRITION
The silica slurry is pumped to the separator density tanks and further screened and purified prior to processing.
CLASSIFICATION AND WASHING
The slurry, now in a ready form, is put through a classifier and washing process to remove fines and silt, which increases the silica content and reduces contaminants such as iron, titanium and aluminium.
The slurry then undergoes a separation process using a three-stage spiral separation circuit which will further remove metals.
The slurry is passed through a magnetised matrix separator and the magnetic materials are filtered. This results in a further increase in silica content, and reduction in iron, titanium and aluminium.
The processed slurry, now in a pure white form, is pumped through a final screening process before it is de-watered using a hydrocyclone, and stockpiled to reduce moisture content.
LOADED FOR TRANSPORT
The final product is then loaded onto 60 tonne double road trains for transport to the lay-down storage facility, and thereafter onto the ship.
Mining and Processing Operations
Mining and processing operations are intended to operate 24 hours per day and 365 days per year. Where possible personnel would be rostered using local employees and on-site camp facilities may not be required.
Classification and Washing
Final Screening and De-watered
Loaded for Transport
Drilling and sampling will determine the initial product grades, and further testing using the beneficiation process will identify an indicative assessment of the output product. Initial grade results are typically lower than the finished product grades after the completion of the beneficiation process.
Commercial Grade Silica Sand
After beneficiation the output product would need to meet this range of specifications:
|Parameter||Specification Photovoltaic Glass||Specification Container Glass|
|Particle Size||109-700 microns||109-700 microns|
|Distribution||24-140 mesh||24-140 mesh|
|Silica (SiO2)||> 99.5%||> 98.5%|
|Iron (Fe2O3)||< 0.01% (100 ppm)||< 0.04% (400 ppm)|
|Titanium (TiO2)||< 0.04% (400 ppm)||< 0.1% (1000 ppm)|
|Aluminium (Al2O3)||< 0.10% (1000 ppm)||< 0.50% (5000 ppm)|
Product Specifications Risk
A significant project risk is not meeting market specifications for the product. Failure to meet product specifications may result in selling the products at discounted rates, or not being able to find buyers for the product.
Dune Buggy Esperance Project
The sands mining process is relatively straight-forward and involves non-specialised machinery which is readily available. A basic description of the typical processes are provided as an example:
The process starts with heavy equipment removing the surface vegetation, which is relocated and stored for use in the consecutive site rehabilitation process.
Proposed mining sites are low vegetation, mostly cleared with some patches of rehabilitated blue gum. Predominantly native scrub.
Topsoil layer is ripped to about 500mm using dozer mounted ripper and then removed and stored or translocated for use in the consecutive site rehabilitation process.
SOIL (OVERBURDEN) REMOVED
Soil (overburden) is removed by heavy equipment to gain access to the identified silica resource. Typically shallow, and depth no greater than 1-25 metres.
Silica sand is removed by heavy equipment and moved by front-end loader to a mobile hopper with a stage one washing and screening system that removes any oversized materials. The silica as a slurry is pumped to the on-site processing plant.
The post-extraction area is rehabilitated in a consecutive process replacing soil and vegetation previously removed.
Rehabilitation will occur possibly concurrently with mining activities so that areas disturbed are quickly remediated as part of the mining process. Final site rehabilitation will include reshaping to restore a land surface ready for the replacement of both subsoil and topsoil and natural lake development with supporting vegetation. Seeding and revegetating, being mindful of protecting for wind erosion, and the replanting of seedlings that best restore the original native vegetation will then follow. Final site elevations will be lower after restoration.