Doubtful perspective of chlorine-purified natural graphite for Li-ion batteries

Jan 27, 2019

In the beginning of 2019, well-known key players of the global natural graphite market from Canada, US, EU and Australia show obsession with idea to overtake China’s leadership to become major stakeholders in the materials supply chain for Li-ion batteries manufactures. The investors’ mood is warmed up by recent growth of spherical graphite in price.

A row of mining companies already claim that they have nearly completed full industrial cycle converting graphite ore into ready-to-use battery grade coated spherical graphite. However, one of the important stages of this process, the graphite purification technology, still remains a white elephant in the room.

The indisputable positive side of the issue that the overwhelming majority of suppliers are keen to move away from dirty acid leaching, at least from hydrofluoric acid. At the same time, some of them took to purification solutions based on chlorine or chlorine containing agents. That, at first glance, is more lucrative, simple and environmentally friendly. But in reality it is not the case. So, let take a look at some common misconceptions by investors related to the chlorine purification of natural graphite.

Myth №1: Chlorine is safe. To understand that is untrue it is quiet enough to go through any Chlorine Safety Data Sheet (for example by BOC, 2013) or to check Chlorine Accident Records (Community Documentation Centre On Industrial Risk. Review of accidents involving chlorine by G. Drogaris, 1992). Chlorine tends to leaking and it is enormous task to contain the substance at temperatures more than 1000°C. In case of inner graphite lining, which is mandatory for purification process, the last one does not prevent chlorine from leaking at all. Moreover, the technology requires fluidization with pressurized gaseous area under the bed. The waste gases after purification furnace should be treated in a specific way as well. So chlorine cannot be safe in such technology by default.

Myth 2: Chlorine provides low-cost purification. According to some business plans, which went public recently, by leading graphite companies, chlorine purification costs range nearly from 500 to 700 $/ton. But what is about its rival technology, classic thermal purification at 3000°C? The costs are at the same level. The argument that chlorine process features low energy consumption rate is totally inconsiderable, because in terms of costs the share of energy is about 5-15% and does not matter by and large. The main reason of the mentioned above misconception is that the classic high temperature purification technology seems a bit complicated. There are a few engineering companies in the world that position themselves on the global market as capable to put such non-chlorine technology on track. Unfortunately, this handful of companies have set a speculative price due to their unique proposal.

Myth 3: Chlorine ensures excellent quality. The truth is if you purify natural graphite with chlorine at low temperatures, it is impossible to reach excellent grades. Graphite will never become genuine graphite without high-temperature treatment at 2800-3000°C. According to experimental studies traces of chlorine will inevitably present in final product. Of course, you probably will obtain battery grade material, but never something else with outstanding unique properties to offer your product on other growing markets. The risk is that slight uncertainty in modern technologies with their rapid development might crash the Li-ion batteries market in a flash making the one-sided technology for the narrow purpose useless. Investors misled by marketers and chemical engineers waste huge amount of costs betting on the shaky and vulnerable technology with uncertain future.

Thus natural graphite purified with chlorine will never become green and smart.

All the best and have a nice day wherever you are.


January 27, 2019

By Serhii Fedorov / T&MEC

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