Pavel, part of your "Mud" effect is due to the historical "September Effect" of global markets.  The other part, undoubtedly, is due to the "Lepidolite garbage" you mentioned.

To enlarge on what Pavel has stated about the uneconomical use of Lepidolite by the Chinese to produce LCE please take a look at the article linked below:

Analysis-China lithium boom slows as sagging prices batter high-cost miners (yahoo.com)

"It costs about 80,000 yuan ($11,120) to 120,000 yuan to process a ton of LCE from lepidolite in China, while it costs around 40,000 yuan and 60,000 yuan to get the same volume from brine deposits and spodumene, respectively, analysts say."

"Five China-based analysts forecast spot prices will stay in the 100,000 yuan to 120,000 yuan range in 2024 or rise slightly higher, despite a futures rally boosted by restocking demand after the Lunar New Year holiday."

100,000 Yuan converted to USD today, 10 September 2024, is $14,040.  120,000 Yuan converted to USD today is $16,848.

For reference:  Today's price of lithium is below $10,100 USD according to information on: Daily Metal Price: Lithium Price (USD / Metric Ton) Chart for the Last Week

So, Pavel's assertion " Another “good” news is, that the Lepidolite mining does not make sense anymore, because the spot price does not cover the processing costs (from ore to some meaningful concentrate)" is  correct. 

It doesn't make sense, at least in a Free Market Economy, but China isn't a Free Market and the CCP is propping up a lithium mining industry that would otherwise be losing money to the point of bankruptcy.  China did the same thing with the nascent Solar Panel industry for years when they propped up a fledgling Photovoltaic industry making solar cells and solar panels at a loss so they could focus on exporting those units to other countries, especially to Europe and the U.S., in order to undercut the solar cell manufacturing in those industrial centers while China took a hit by sustaining a loss for their own solar production industry in order to eliminate competition in Europe and the U.S.  This "strategy" is economic warfare and it is a well oiled machine in the way China deals with the West.  Taking an economic hit in order to destroy foreign competition initially and then to dominate the world market later at a profit can only be done in a country that ignores the practical reestrictions of a market where survivorship is dictated by the absolute need to make a profit.  The "strategy" of the CCP is plain and simply a form of "Economic Warfare".

"Much of that investment has been in the southern province of Jiangxi, home to some of the newest lepidolite projects that are rich in kaolinite, a clay mineral with lower lithium content that costs around 120,000 yuan per ton of LCE to produce, according to research firm CRU."

So one might easily think that in order for the CCP to continue this negative profit approach to lithium mining that the economy of China would have to be booming in order to offset the losses sustained by their economic warfare strategy regarding lithim domestic mining in China.  Well, in relation to past years of economic growth in China the present period is not doing as well.  China is having some serious economic problems that are not limited to just the disaster with their real estate market.

The articles below are proprietory, but the little glimpse that is allowed the non paying viewer confirms that China is having economic problems:

Nomura Expects China’s GDP Growth to Slow to 4.5% in 2024 (caixinglobal.com)

China’s New Economy Industries Slip as Labor Inputs Fall to Nine-Year Low (caixinglobal.com)

The World Bank Group assessment of the economy in China back in April of this year does not support a glowing economy this year in China:

China Overview: Development news, research, data | World Bank

"Over the medium term, China’s economy is expected to undergo a structural slowdown. Potential growth has been on a declining trend, reflecting adverse demographics, tepid productivity growth, and rising constraints to a debt-fueled, investment-driven growth model. Structural reforms are needed to reinvigorate the shift to more balanced high-quality growth."

Andrew Collier from Orient Capital Research gives a less than glowing assessment of the Chinese economy in this video:

President Xi is 'not being told' how badly China's economy is doing: Andrew Collier (msn.com)

"China’S giant economy faces an equally giant crisis of confidence—and a growing deficit of accurate information is only making things worse. Even as the country wrestles with a property crash, the services sector slowed by one measure in August. Consumers are fed up. Multinational firms are taking money out of China at a record pace and foreign China-watchers are trimming their forecasts for economic growth."  

The above paragraph is from a proprietory article titled "The Real Problem with China's Economy" dated 5 September 2024 in the Economist.  No, I don't have a subscription, so that first paragraph is all that was available to me, but it certainly doesn't paint a picture of a robust Chinese economy, does it?  The subtitle of the article warns that China may be going to repeat some of the huge economic mistakes made years ago by the Soviet economic decisions.

So, China is playing a game of Economic "Chicken" with the West in the hopes that its own domestic consumption will somehow magically and dramatically increase and that the same magic will happen in the realm of increased foreign investment in China? 

"Magic" is sort of like "Hope" in the realm of efficacy for the long term, although it can certainly influence short term positive beneifits.  So, the questions remains: 

When will the short term benefits of "Magic" run out and leave China and its economy facing reality? 

When will the CCP support of an unprofitable approach to lithium mining and processing of Lepidolite peter out and be judged by the powers that be in the CCP as no longer a sustainable method of conducting economic warfare with the West?  

The answer to that question is dependent upon how much economic pain the CCP is willing to sustain as they slip deeper into what potentially could be economic chaos.  They can take quite a "hit" on their economy in the short run, but when does the extent of the "hit" become the tender for a political domestic fire by the masses and threaten to yield an ustable domestic political situation for the CCP... or worse?

Those are broader questions that reach far outside just the small area of the economy occupied by the lithium mining sector in China, but "Change" is always possible and the threat of change is always in the vision of the CCP. 

The Central Committe of the CCP, the Politburo and the Standing Committee of the Politburo prize above all else a growing economy that has both the benefit and the approval of the population in order to minimze any potential domestic population unrest toward the existing power structure.

Central Committee of the Chinese Communist Party - Wikipedia

Politburo of the Chinese Communist Party - Wikipedia

Politburo Standing Committee of the Chinese Communist Party - Wikipedia

As long as the CCP feels that its current economic policies are the correct course then they will continue to use such strategies as undercutting foreign lithium mining efforts by providing economic subsidies to S.O.E. (State Owned Enterprise) in China that operate at a loss in order to engage in the costly process of supporting a Lepidolite mining and processing scheme that doesn't pay for itself and already operates under water vs the world market for lithium minerals.

The key here, Pavel, is to keep an eye on the domestic economy of China.  If it is in the recovery stage then it is highly likely that CCP support for a money losing Chinese Lepidolite mining will continue, but if the overall Chinese economy continues to slip and slide then, like a lifeboat with too many people in it to remain afloat, the CCP will have to eventually abandon some of its passengers that are losing money and rocking the economic boat of China.

Okiedo