Ann: Bauxite Technical Specification for Offtake Negotiations, page-20

Hi ddzx,
I was going to reply to you on the LIN thread but I simply can't bring myself to be so cruel.
I noted you had some fun at the expense of CAY over there in a number of posts where you posted sarcastic emoji's laughing at our OPEX costs detailed in our recent PFS.
You stated you were ready for the recent LIN announcement. I somehow doubt that. I thought I might provide you some reason as to why.

Desilication is an OPEX cost, and you recently stated that the LIN OPEX cost was US$30/tonne MAX.
Now that the LIN Maiden Resource announcement states 11%+ Reactive Silica, I was wondering if you may have reconsidered.
What is your new estimate for LIN OPEX?
I note the CAY reactive silica is under 2%.

To help you estimate I offer an extract from the link I post below it.

Abstract
Reactive silica is the most detrimental impurity in bauxite. When bauxite is contacted with Bayer liquor, reactive silica dissolves and then precipitates as a sodium aluminum silicate known as the desilication product (DSP), which is discarded along with the bauxite residue and maintained in long-term storage facilities. DSP recycling using bauxite residue lime sinter-leach is prohibitively expensive due to the high energy requirement for heating as well as high investment costs. In the sandy desilication product process, DSP is coarsened by controlling the desilication conditions, which enables the DSP fraction of the residue to be concentrated by physical separations. The DSP concentrate can then be recycled by sinter-leaching, whereby sodium and aluminum are returned to the Bayer process, reducing the burden associated with bauxite residue and facilitating total residue treatment options. Results are presented herein demonstrating DSP particle enlargement by seeding the reaction and controlling the supersaturation.

Introduction
The principal components of bauxite ores are aluminum-, iron-, and silicon-bearing minerals. In the Bayer process for recovery of alumina from bauxite,1 aluminum is dissolved into hot alkaline solution whilst iron is relatively insoluble. “Reactive silica” in the form of silicate minerals, such as kaolinite, typically dissolves and reprecipitates as sodium aluminum hydrosilicate, known as the desilication product (DSP). Desilication of the leach liquor for low-temperature digestion refineries is essential to meet alumina product specifications, minimize scale formation on heat transfer surfaces, and remove other impurities from the Bayer liquor. However, precipitation of DSP is costly, as sodium hydroxide (the key reagent in the Bayer process) and aluminum (element for the product alumina) are lost, being discarded as part of the bauxite residue. It has been stated that bauxites with reactive silica concentrations greater than approximately 6 wt.% to 8 wt.% cannot be processed economically2,3 due to losses of sodium hydroxide, which is approximately 1 tonne of NaOH per tonne of reactive silica due to formation of DSP. Furthermore, DSP in the bauxite residue adds to the complexity of processes for bauxite residue neutralization, tailings area remediation,4 and recycling the residue for iron recovery, as well as subsequent use of residue in building materials.

https://link.springer.com/article/10.1007/s11837-019-03617-2