Core Technology Analysis of Lithium Extraction from Salt Lakes (Part 3)

Further advancement of lithium extraction by adsorption method

Moving the lithium extraction section forward, moving from "old brine lithium extraction" to "original brine lithium extraction"

Due to the fact that the lithium recovery rate in the salt field section (brine extraction, transportation, and gradual beach drying) is only about 40%, which is the link with the greatest entrainment loss, efforts have been made to move the lithium extraction process forward and become the focus of the current industry. The most extreme process design and current key technology is to shift from "old brine lithium extraction" to "original brine lithium extraction", achieving true DLE (Direct Lithium Extraction).

Among them, adsorption method plays a core role in raw brine lithium extraction due to its compliance with the industry trend of "low grade, low cost, and green lithium extraction technology", while further treatment of the analytical solution can be integrated with gradient membrane method, electrodialysis, and extraction methods. However, the current industrialization still focuses on the coupling of adsorption and membrane, similar to old brine lithium extraction but with different details in the process flow.

Compared to the old brine extraction lithium with "magnesium lithium separation" as the core, the adsorption of the original brine extraction lithium requires a one-step selective separation of lithium from elements such as sodium, potassium, magnesium, and boron. By using adsorption to replace the desalination and potassium removal functions of salt fields, the magnesium lithium separation load of the nanofiltration device is reduced, while ensuring that it does not affect the potassium extraction of the final lithium extraction tailings.

At present, the commercial production capacity of lithium extraction from raw brine has been launched and constructed on Yiliping Salt Lake and Dachaidan Salt Lake in Qinghai. If fully verified in industrial continuous production, it will bring epoch-making breakthrough significance to the lithium industry in the future and change the industrial pattern of lithium supply.

The difficulty in achieving lithium extraction from raw brine undoubtedly lies in the efficient adsorbent. In the same situation, lithium extraction from raw brine means that the amount of brine that the adsorption device needs to process will significantly increase, and the technical difficulty will shift from magnesium lithium separation to sodium lithium separation.

At present, some leading adsorption material manufacturers can achieve universality between old brine adsorption and original brine adsorption, and can switch as needed. The current controversy in the industry regarding lithium extraction from raw brine mainly lies in the belief that there is still a lot of room for optimizing the recovery rate through improving the salt field system and lean production. Alternatively, lithium extraction can be carried out in the middle of the salt field after removing sodium from the sun, and finally potassium extraction can be carried out. This can also achieve the "lithium extraction process forward", but there is no need to move forward to the raw brine, resulting in excessive brine treatment capacity in the concentration and separation device.

We believe that from the perspective of actual production, these are undoubtedly practical suggestions, but for promoting the development of the lithium industry, the technological revolution of extracting lithium from raw brine is of greater significance.

At the same time, in addition to the original brine adsorption carried out in the front-end, attempting to directly produce lithium hydroxide products using bipolar membranes and electrolysis processes in the back-end has also become a key technological breakthrough in the lithium industry in China and overseas. Although this is not a completely new approach, it has received unprecedented attention and technological development has significantly accelerated in recent years. If commercialized in the future, lithium extraction from salt lakes will undergo a qualitative change in both production efficiency and product added value.

08

In the mid-term of the future, technological progress and process standardization

Optimize the capital investment intensity for lithium extraction capacity in salt lakes

According to our tracking statistics on global salt lake lithium extraction projects, overall, the average capital investment intensity of new processes such as adsorption is slightly lower than that of precipitation: the average capital investment intensity of ton LCE using non precipitation lithium extraction process is 19096 US dollars/ton, 1.28 billion yuan/ten thousand tons (ranging from 8955 to 37727 US dollars/ton LCE, RMB 602 to 252 million yuan/ten thousand tons), while the precipitation method is 20549 US dollars/ton RMB 1.37 billion/10000 tons (ranging from 6443-41210 USD/ton, RMB 43-2760 million/10000 tons).

Of course, this is related to the fact that some of the adsorption capacity is grafted onto mature and established salt field systems, rather than projects with complete green spaces. Compared with itself, the adsorption method has been developing since 2017, and we have noticed that the intensity of capital expenditure is gradually decreasing. Taking a leading adsorption material company as an example, its total equipment supply contract amount has decreased from 580 million yuan/10000 ton LCE in 2018 to 230 to 260 million yuan/10000 ton LCE (from 8640 US dollars/ton to 3408-3886 US dollars/ton), and EPC contracts have decreased from 1.56 billion yuan/10000 ton LCE to 490 million yuan/10000 ton LCE (from 23310 US dollars/ton to 7324 US dollars/ton). We believe that in addition to the low capital investment required for mature capacity expansion, it also reflects the technological progress and greater proficiency of adsorption methods.

09

The high-quality development of salt lakes is not just about breakthroughs in lithium extraction technology

Further clarification is needed on the ecological mechanism of salt lakes

In the current restless lithium industry, we remind industry and capital market investors that the high-quality and sustainable development of lithium resources in salt lakes is not only about breakthroughs in lithium extraction technology, but also about clarifying the mechanisms of salt lake ecology and circulation.

The core behind it lies in the fact that salt lake resources are dynamically flowing (regardless of intergranular brine, deep brine, or surface brine), rather than the static existence of solid lithium deposits. Therefore, the recoverable reserves (water yield reserves) and brine grade of salt lakes are subject to fluctuations.

At the same time, the ecology of salt lake mining areas is extremely fragile and difficult to restore, and careful selection of processes is needed.

Overall, we believe that the development barriers and complexity of lithium extraction from salt lakes are much higher than those of solid lithium mines, and at least require the integration of geological, chemical/hydrometallurgical, and environmental engineering knowledge.

For example, the hydrological model of salt lake circulation, the relationship between brine extraction and freshwater level, the layout of brine extraction wells and observation points, the location of reinjection of adsorbed desorbed liquid, flood control design, etc., all require comprehensive research.

In addition, we believe that there is no perfect process route for lithium extraction from salt lakes, only the most suitable components for salt lake brine, the most suitable supporting conditions for mining areas (energy, fresh water, roads, terrain, altitude, evaporation rate, climate conditions, etc.), and the most suitable process route for resource merchants and downstream market needs.

At the same time, technological progress is not achieved overnight. There is a clear distinction between small-scale, pilot, and industrialization, and it is necessary to combine process ideas with the practice of continuous industrial production. The path of technological progress usually presents a spiral development after accumulating time and lessons learned. The accumulation of quantitative to qualitative changes may ultimately lead to subversion.