top of page

Lithium Refining Pathways

"Ark Blue and Green+ : Innovative Lithium Solutions for a Sustainable World"

The lithium refining sector has four primary refining pathways which can be represented as Grey Refining, Yellow Refining, Blue Refining and Green+ Refining.

Lithium Ark is the inventor, developer and patent-holder of the Blue and Green+ Refining pathways. 

In side-by-side comparisons, Green+ Refining provides the most superior set of ESG benefits and financial performance among all pathways.  For some companies, Blue Lithium Refining is a compelling alternative since it generates zero waste in the manufacture of Lithium Hydroxide-BG, a vast improvement over conventional Grey Refining.  

The Refining pathways are summarized and evaluated below:

GREY Lithium Refining

Conventional Grey Lithium Refining, which represents the legacy or traditional pathway of lithium refining, first converts Lithium Chloride feedstock into technical grade (TG) Lithium Carbonate, which is then converted into battery-grade (BG) Lithium Hydroxide.


A simplified Flow Diagram for Grey Lithium is represented by:

The conversion of each ton of Lithium Chloride to Lithium Carbonate-TG requires nearly two tons of Soda Ash as reagent. Then, the subsequent conversion of Lithium Carbonate-TG into Lithium Hydroxide-BG requires Lime and Hydrochloric Acid (HCl) for reagents. In some cases, a Grey Lithium Refinery can consume 5 tons of reagent and generate up to 14 tons of waste & carbon dioxide (CO2) to produce a single ton of Lithium Hydroxide-BG.


Grey Lithium Refining is a chemically-intensive pathway resulting in:

  • Mountains of Reagent (Lime, Soda Ash)

  • Costly Reagent Transport to/from Remote Sites

  • High Waste Generated that is Difficult/Costly to Dispose

  • High CO2 Emissions

  • Low Lithium Recovery (8-12% Lithium Losses)

  • High Energy Intensity

  • High Fresh Water Use

  • Leading to High OPEX/ton

  • Requiring High CAPEX in Equipment & Fixed Assets


Each year, million of tons of Soda Ash, Lime and/or Hydrochloric Acid are transported 1000’s of kilometres to/from remote sites to support the Grey Lithium Refining sector.


All these factors make Grey Lithium Refining unnecessarily complex, financially wasteful, and environmentally unsustainable. Grey Lithium processing faces an uphill battle to scale up 10x over the coming decade without incurring significant costs, both financially and ecologically.

BLUE Lithium Refining

Lithium Ark is the inventor and patent-holder of Blue Lithium Refining. The process operates at the intersection of the lithium- and nitrogen-processing sectors.


A simplified Flow Diagram for Blue Lithium is represented by:






Blue Lithium Refining uses Lithium Carbonate-TG as feedstock. As the flow diagram shows, Lithium Carbonate-TG is converted directly into Lithium Hydroxide-BG, with the added benefit of Potassium Nitrate as by-product. However, Lithium Carbonate feedstock contains carbon in its molecular structure. Inherent to processing carbon-based lithium feedstock, both Blue & Grey Lithium release carbon dioxide. This characteristic is far from ideal if one wishes to completely de-carbonize lithium processing itself. 


How Blue Lithium Works:

Blue Lithium Refining is based on a reciprocal salt system:

Lithium Carbonate-TG is blended with Nitric Acid (HNO3) and Potassium Hydroxide (KOH). The mixing of these three ingredients results in a new solution that includes: Lithium Nitrate (LiNO3), Potassium Hydroxide (KOH), Lithium Hydroxide (LiOH) and Potassium Nitrate (KNO3).


Ultra-Low Cost Crystallization:

Potassium Nitrate (KNO3) has a remarkably steep solubility curve that enables the Blue Refinery to selectively crystallize KNO3 by cooling (20 °C) without co-crystallizing Lithium Hydroxide (LiOH). The slight downward slope of LiOH’s solubility curve enables the Blue Refinery to selectively crystallize LiOH via evaporation at higher temperature (90 °C) without co-crystallizing KNO3.


A moderately-sized Blue Lithium Refinery generates notable quantities of KNO3 fertilizer at virtually no cost. This is made possible by converting 3 low-value inputs (LiCl, Nitric Acid, KOH) into 2 high-value end products (LiOH-BG and KNO3). Low-temperature processing minimizes the plant's thermal power consumption.






Blue Lithium Refining is a process that is highly sought by companies in the nitrogen processing sector who wish to exploit existing capabilities in the manufacture of urea, ammonium, and other nitrogen-based products to also produce battery-grade lithium chemicals. A Blue Lithium Refinery (30ktpa) would generate ~85% of its revenue from sales of LiOH-BG and the remaining sales from Potassium Nitrate.


YELLOW Lithium Refining

Lithium Chloride Electrolysis is referred to as Yellow Lithium Refining.

Some companies are pouring significant brainpower and financial resources into developing a means of converting Lithium Chloride (LiCl feedstock) into Lithium Hydroxide-BG by electrolysis. Unfortunately, the goal of directly electrolyzing LiCl into LiOH-BG has proven devilishly challenging.

If one assumes that LiCl-Electrolysis may one day be successfully applied to lithium refining, it is likely to suffer from a number of inherent disadvantages: 

  1. costly pre-treatment of the brine is required due to the high sensitivity of electrolysis membranes to impurities, leading to higher processing costs.

  2. the maximum electrical efficiency is only 60% to 70%. High energy consumptions increases OPEX/ton of lithium.

  3. overcoming poor power efficiency at high manufacturing through-put necessitates higher CAPEX in electrolysis equipment

  4. LiCl-Electrolysis has never been industrially-scaled.

By contrast, the Green+ Lithium Refining process replaces LiCl-Electrolysis with KCl-Electrolysis.

KCl-Electrolysis is far superior to LiCl-Electrolysis. KCl-Electrolysis is already industrially-scaled worldwide at ~2 million tons annually. This means that its equipment and processing are already proven, standardized and relatively low-cost. Further, KCl-electrolysis is highly power efficient (~98%), minimizing OPEX/ton. These factors provide Green+ Refineries significant competitive advantage over Yellow Refineries by maximizing ESG benefits and profitability.

GREEN+ Lithium Refining

Lithium Ark is the developer and patent-holder of Green+ Lithium Refining, a process that combines the best practices of the lithium and chlor-alkali sectors.


A simplified Flow Diagram for Green+ Lithium is represented by:


The Green Lithium process directly converts Lithium Chloride (LiCl) feedstock into battery-grade Lithium Hydroxide (LiOH-BG). Through the company's trademarked process called Lithium Flex, the Green Refinery retains the optionality to easily convert LiOH-BG into Lithium Carbonate-BG by simply adding CO2. Lithium Flex enables Green Refineries the flexibility to produce either Lithium Hydroxide or Lithium Carbonate on-the-fly to respond to ever changing battery chemistries, architectures and markets.


How Green Lithium Works:

Green Lithium Refining is a novel process that borrows several key building blocks found outside the lithium sector, namely the chlor-alkali sector, and applies these proven methodologies to address short-comings in traditional Grey Refining. The first building block is a reciprocal salt system that performs the heavy lifting of important chemical reactions – and does so in a very predictable, repeatable and dependable way.

The reciprocal salt system for Green Lithium is provided by:


Lithium Chloride is mixed with Potassium Hydroxide (KOH), creating two new salts Lithium Hydroxide (LiOH) and Potassium Chloride (KCl). KCl is a valuable by-product purchased in large quantities by the food industry.


Favourable Solubility Curves Enable Low-Cost Crystallization:

A Green Refinery is able to easily separate LiOH and KCl from solution because the solubility curves for these salts are sloped in inverse directions.



Specifically, a Green Refinery is able to selectively crystallize KCl from solution by cooling (~20 °C) without co-crystallizing the LiOH. Similarly, the Green Refinery can then selectively crystallize LiOH from solution via evaporative heating (~90 °C) ) without co-crystallizing KCl. Once crystalized, Lithium Hydroxide-BG and Potassium Chloride are washed and dried.


GREEN+ Lithium

At its core, a Green Lithium Refinery is primarily a crystallization module that exploits a reciprocal salt system and advantageous solubility curves to produce LiOH-BG and KCl-Food Grade. Better yet, a Green Refinery can upgrade its capabilities to a Green+ Refinery by adding an electrolysis module to further increase ESG and financial performance. 



A Green+ Refinery exploits electrolysis to recycle its Potassium Chloride (KCl) back into Potassium Hydroxide (KOH) to start the process anew, making the entire process circular. The Green+ Refinery's electrolysis of Potassium Chloride also generates beneficial by-products such as Hydrochloric Acid (HCl), Chlorine Gas (Cl2), and Hydrogen Gas (H2).


The Green+ Refining process eliminates the need for externally-sourced reagents, such as Lime and Soda Ash, as well as carbon-based feedstocks, such as Lithium Carbonate. As a consequence, a Green+ Refinery using Lithium Chloride feedstock generates virtually zero waste or carbon emission.   

bottom of page