Banter and General Comments, page-7737

I'll try to fill in some of the gaps in Spodumene specifications and the impact of impurities on the conversion costs to add to the discussion.

Grade:
Generally accepted grade is between 5.5% and 6.2% (A40 claims production of 6.3% (super grade?) and Greenbushes produces some of its spodumene at 6.5% to meet customer requirements while it also remains the reference point standard for it's 6% grade product). Obviously the lower the grade, the higher the impurities and the more material required to process the same quantities of Li Chemicals. One of the production constraints of S/Cs (spodumene converters) is the calciner size. The calciner heats the spodume concentrate to around 1050°C whereby α-spodumene is converted into the β-spodumene form which is then able to be further processed into Li chemicals by acid leaching. Therefore spodumene grade has a significant effect on calciner throughput.

Impurities:
Impurities are partially carried through to the final Li Chemical product and are in my opinion more important than spodumene concentrate grade. The reagent requirements to remove them can be a major burden.
Major impurities include Fe2O3 (<1.5%), Mica (<3%), Feldspar, Quartz, Phosphorus, Potassium and Calcium. Magnesium is a major impurity for brine, however I'm trying to focus on Australian spodumene.
There are successful methods to minimize impurities, but when people talk about EV BG Li Chemicals being 98%, it's the impurities in the remaining 0.2% that have a major impact. They constrain initial battery performance and over hundreds or thousands of battery cycles they increasingly reduce performance and reliability.

Klinkers:
The impurity effects on S/Cs add considerable costs and texhnical complexity. Many posters like to use the term "klinkers" so I'd like to attempt to explain what that means for S/Cs. During the initial calciner stage, as mentioned the α-spodumene is heated to 1050°C.
Iron, Phosphorus, Pottasium and Calcium have lower melting points and form clumps (klinkers) that trap some quantities of desirable spodumene. This reduces the recovery rate of Spodumene while adding costs, inefficiencies and extra steps. Klinkers can be removed and processed but the recovery rate of Spodumene from the klinkers isnt excellent. While it's my opinion that klinkers cannot be totally avoided by S/Cs, the quality of the raw spodumene concentrate has a major impact.
Raw material processers have systems in place to limit the levels of these impurities not withstanding some technological difficulties. IMHO this becomes a cost / benefit decision by the miner to determine the most economic provision of product while conforming to client specifications. The initial levels of impurities in the Ore are a major factor to be considered. I would suggest Fe levels are the greatest concern.

Grain size:
The particle sizing of spodumene concentrate is also of significant importance to S/Cs operational efficiency.
Acceptable grain size ranges from 0.07mm to 3mm. There is much speculation regarding Coarse grain vs fines and what the S/Cs are willing to specify.
It may seem trivial or innocuous compared to the other impurities however a major consideration for S/Cs is the dust proportion. High levels of dust can have a critical impact on S/C plant operations at the calciner stage. Dust can easily be blown out during the calciner stage, accounting for major losses of product if the converter isn't tuned to handle.
Grain size is also important at the calciner. The heating time differs between particle size with smaller particles heating faster and coarse grain calciners more susceptible to dust losses.

Moisture content:
There are clear logistical reasons for some producers to supply spodumene concentrate in WMT, however this is not ideal for converters that like to deal with a dry product. Removing the moisture adds another step and cost to the converters.

All of these variables have varying effects for each S/C. This is why the talk of the time it takes to tune a converter to a spodumene supplier is of such great importance if that converter is seeking to provide a cost effective high quality BG product. The individual processes are tailored to the concentrated spodumene provider.
Some converters have become more capable of dealing with Klinkers or have adjusted calciner stages to effectively deal with dust loss. Other impurities have very dialed in usage of reagents achieved by long term offtake commitments. Peak efficiency is gained over periods of years. This is one of the many reasons that newer spodumene producers have received lower pricing than peers. All the adjustments, fine tuning or additional steps add up to conversion costs.

The importance of delivering a consistent supply of Spodumene cannot be underestimated for converters to be successful. Even talk of blending A40 & GXY spodumene to achieve a higher SC grade that regularly pops up shows a lack of understanding of the Converter fine tuning.

Grade is certainly important, but SC6 is not the only measure of quality its simply the percentage of Spodumene in the concentrate.
Impurities matter
Partical size matters
Water content matters.

Ive done my best to summarize this information. It no doubt contains mistakes and I would appreciate any corrections or additions to further educate myself and others.
AIMHO