The Potash Deposit
The Mines of Potash in Alsace, a region in Eastern France, are a testament to the rich underground resources and the robust mining operations that have significantly contributed to the region’s economic history. The discovery of extensive potash deposits in the early 20th century marked the beginning of this era. These underground reserves primarily consisted of potash salts, including potassium chloride (KCl) and sodium chloride (NaCl), which were vital for various industrial applications, particularly in agriculture as fertilizers. The mining operations began in earnest following the establishment of several concessions between 1906 and 1912, under the unique legal framework of Alsace-Moselle, reflecting the region’s distinct cultural and historical context.
The mining techniques employed in the Alsace potash mines were notably advanced for their time, evolving steadily to meet the increasing demands and challenges of deep underground extraction. Initially, the mining involved traditional underground methods, but over time, this evolved to incorporate more sophisticated and efficient technologies. This period saw the construction of numerous mine shafts, sprawling underground networks, and the development of specialized equipment to extract and process the potash salts. The potash extracted from these mines was not only significant for France’s agricultural sector but also played a crucial role in the nation’s industrial growth.
However, the peak of mining activity eventually led to a gradual decline, primarily due to the depletion of accessible potash deposits and shifts in global market dynamics. By the 1960s, the focus shifted towards managing the environmental impacts of mining operations, leading to a phased closure of the mines. This transition involved meticulous efforts to address issues such as land subsidence, groundwater contamination, and the management of mine tailings and salt piles. The closure of the mines marked the end of an era in Alsace, leaving behind a legacy of industrial prowess and a complex challenge of environmental restoration and economic transition for the region.
The Short-Lived Special Landfill
That transition began with the inception of Stocamine in an abandoned potash mine in Wittelsheim. The concept was groundbreaking: to use the mine’s deep underground caverns for the safe storage of non-radioactive hazardous waste. This approach was seen as a step forward in dealing with toxic materials like asbestos, arsenic, or mercury, which pose significant risks to public health and the environment.
However, the optimism was short-lived. In 2002, a fire broke out in one of the storage areas, leading to widespread concern about the potential release of toxic substances. This incident marked a turning point for Stocamine. It raised critical questions about the safety and viability of underground waste storage, particularly in a region like Alsace, known for its rich natural and cultural heritage.
The aftermath of the fire brought Stocamine under intense scrutiny. Investigations revealed lapses in safety protocols and management, casting doubt on the facility’s ability to ensure long-term containment of hazardous materials. Environmental groups and local communities, already wary of the project, intensified their opposition, citing risks to the Alsace aquifer—a vital source of drinking water.
The Dawn of a Lithium Era?
Water analyses were ordered among the court debates on what to best do with the waste trapped in the former Potash Mines. And while nobody really paid attention, there was a treasure hidden in plain sight in the middle of the results: lithium.
Every single sample of water tested from the various piezometric levels actually returned lithium in an array of concentrations, but often in quite high ones. When digging up the case, this actually makes good sense. The geology of the potash deposit resembles many other ones in the World that are known to be lithium-rich, such as Atacama.
The lithium resource mapping actually doesn’t stop there. BRGM studies show that Lithium is quite intensely located in the hills of the Vosges Piedmont, which borders the potash basin on its western flank. So, the water cycle at work in that geographical area explains a lot of the very interesting lithium concentrations found in the former mines underground!
Lithium’s presence in that region isn’t a surprise either, considering companies like Vulcan Energy Resources have been prospecting the same aquifer at different depths but within the same basin with quite a lot of success.
All in all, the mining stars are aligned to finally let the Potash Basin enter the 21st Century and contribute to the World’s Energy Transition!
Direct Lithium Extraction: The Missing Piece
It’s not the first time that a use of the Potash Basin lithium resources is examined. But every time geologists have looked into it, they’ve tried to figure out a hard rock mining operation – similar to the way potash used to be extracted.
Yet, if the rocks in the deposit have respectable lithium contents, they can’t compete with Australian spodumene and its 1.5% lithium concentration. So, economical assessments always led to turning the project down.
In a similar fashion, studies to bring the lithium-rich brines into evaporation ponds have always hit the reality brick wall: climate isn’t dry enough for it to be efficient, and real estate is much more expensive in Alsace than it is in Atacama or in the Andes.
So, lithium was left as a lost cause and not much talked about until I looked it up. And what I discovered, is that the new generation direct lithium extraction techniques have a match made in heaven with this brine matrix!
Highly cost-effective lithium extraction
Two samples of the Potash Mines brines were synthesized in Evove’s lithium test center in the UK, and passed through their lithium extraction bench process. And the results were exhilarating:
- Lithium extraction and recovery was very efficient (over 92% extraction across all steps)
- The treatment train was very straightforward: membranes and ion exchange followed by a refining step to reach battery-grade
- Producing lithium with this process promised EBITDA figures in the 85-90% range with the median lithium spot price over the last two years, and anyways north of 75% even at the lowest lithium has fallen over that time period
There promising results now lead into the next steps:
- Further assess what’s happening in the underground with a detailed hydrogeological study
- Confirm local communities’ involvement and acceptance of the project
- Sample more water from the mines – in the initial locations but also in additional ones, which would be theoretically even better and run a pilot study.
- Look into the financing of the project.
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