"The most important thing is consistent, high quality product (shown here by 3 ticks) "
Producing a consistent, high quality product, day-in/day-out has always been the most important issue and something I've been debating on graphite threads for a very long time.
This article on the subject of the importance of producing a "consistent, high quality product", particularly for the high purity demanded for batteries, a few years ago - "Those Last Few Decimal Places – They Matter More Than You Think" I posted here...
A few years ago the "environmental" issues were not that important since little was known by the general EV buying public about the polluting methods used in China to produce spherical graphite for use in LIB's.
As we move forward, I think you will find these issues will become increasingly important and a number of G companies have identified with this - spending considerable sums to ensure they are looked upon as providing an environmentally friendly raw product.
Tesla is aware of "minimizing environmental impact" and perhaps that's why the North American graphite wannabee's are focusing on other than "acid" purification processes - they hope to supply Tesla.
The recent Washington Post article highlighting the problems of where raw materials were sourced, and how they are produced, has made people more aware when previously most had no idea . People who buy "green" cars want to make sure the cars they are buying are actually "green" - i.e. the raw materials are sourced in an environmentally friendly manner - and in the case of cobalt sourced from the DRC, they prefer it not be produced by "child labour".
I guess each graphite company will determine which method they use and they will be judged on the Western OTA's they achieve - or don't. Even some of the Chinese SPG companies are starting to advertise "Eco-Friendly Flake Graphite" explaining how they are treating acidic and alkaline waste water in an "eco friendly" way.
Researchgate article.....note "environmentally benign will be required"
The caustic roasting (with NaOH)–acid leaching (with HCl/H 2SO4) method can produce graphite with 99.99% carbon content, and remove impurities even at parts per million (ppm) range.
Although this technique allows producing high-grade pro-ducts, it is costly and generates a large quantity of acidic and alkaline wastewater.
The development of alternative beneficiation techniques that are both cost efficient and environmentally benign will be required. One such alternative could
be microwave irradiation
(20min delay)