The two companies have committed to working together to develop an improved thermal processing solution involving pelletising of the vanadium-rich iron concentrate produced by AVL at its Western Australian project.
Metso is a Finland-based, world-leading industrial company offering equipment and services for the sustainable processing of natural resources in the mining and process industries and was chosen because of its renown expertise in grate kiln (GK) processing solutions.
AVL roasting tests show substantial increase in vanadium extraction
AVL chief operating officer Todd Richardson said vanadium roasting technology had not changed much since the 1930s, when cement kiln technology was adapted for salt roasting vanadium-bearing ore.
He added: “Since that time, the technology has gone largely unchanged.”
DFS bench-scale pelletised roasting tests conducted by AVL have shown a substantial increase in vanadium extraction, averaging 95.4% compared to standard rotary kiln extractions of 85-88% considered in the pre-feasibility study (PFS).
The Metso GK is an efficient, low-risk and proven technology for pelletising iron ore in global use that can be adapted for salt roasting.
Vanadium-rich iron concentrate pellets produced during bench-scale roast testing
Confident roasting process can be improved
Richardson continued: “By partnering with Metso, a world leading in pyrometallurgical processing, AVL is confident that the roasting process can be greatly improved.
“Industry standard vanadium extraction is 87% in roasting, but AVL test work shows that much higher recoveries are possible by applying newer roasting technologies.
“Recovering these lost vanadium units has large impact on project economics.”
Next phase of testing to simulate and optimise process
The solution being cooperatively developed involves pelletising concentrate and processing it through a GK system.
Pelletising has been used previously in Europe and China for the processing of primary vanadium-titanium-iron ores.
The benefits of pelletising include improved roasting reaction, minimal dusting and reduced build-up of residues within the kiln.
The next phase of test work calls for pilot-scale testing to simulate and optimise the GK process.
AVL's project has a resource of 183.6 million tonnes at 0.76% vanadium pentoxide, including a high-grade zone of 96.7 million tonnes at 1%
"A unique roasting option for vanadium"
AVL managing director Vincent Algar said the grate kiln offered a unique roasting option for vanadium, which has traditionally been undertaken almost exclusively in a rotary kiln.
He added: “Use of this technology distinguishes AVL from other companies developing vanadium projects and holds promise to make a significant improvement to our vanadium processing through higher vanadium recoveries and more efficient roasting in general.
“The use of Metso’s grate kiln technology and expertise provides us with a crucial competitive advantage.”
Result in higher levels of vanadium extraction
The GK system is a combination of a travelling grate furnace for pre-processing with a rotary kiln for final roasting.
Feed concentrate is formed into pellets of a specific size that are well-suited for the process.
Pellets are then loaded onto the traveling grate and pass through multiple furnace heating zones where progressively hotter and hotter gases from the kiln are forced through the bed of pellets.
This process accomplishes gradual and controlled drying and preheating of pellets while recouping much of the energy from the hot kiln exhaust gases.
The rotary kiln is then dedicated to the final roasting of the pellets after they have been dried and preheated and can be controlled independently to achieve thermal profiles which result in higher levels of vanadium extraction.