Beyond Lithium: Potassium, Boron and Magnesium in Puna Brine

Brine as a Polymetallic Resource

In the public imagination, the brines of the Puna are synonymous with lithium. Yet from a geochemical standpoint, they are complex solutions in which lithium coexists with a range of commercially valuable elements. Potassium chloride, boron compounds and magnesium salts are present at concentrations that, in many cases, far exceed those of lithium itself.

Understanding brine as a polymetallic resource—rather than as a single source of lithium—changes the logic of the business. Every tonne of brine pumped mobilizes not only lithium carbonate or hydroxide, but also a set of co-products and by-products whose recovery can significantly alter an operation's profitability.

Potassium: The Highest-Volume By-Product

Potassium is usually the most abundant accompanying element in Puna brines. During the evaporation process, it precipitates as salts that can be processed into potassium chloride (KCl) or sulfate of potash (SOP), key inputs for the fertilizer industry. Since solar evaporation is already part of the lithium production flow, capturing these salts adds value with a relatively modest incremental investment.

The appeal of potassium lies in its scale: potential volumes are high and there is a consolidated global market. For Argentine projects, selling KCl as a by-product can provide a revenue stream that cushions the volatility of the lithium price, improving financial resilience across the cycle.

Boron: A Niche Market with High Specific Value

The Puna is one of the world's most important boron-bearing regions, and its brines reflect that geological signature with appreciable boron contents. This element has applications in specialty glass, ceramics, fiberglass, agrochemicals and, increasingly, in technologies linked to the energy transition. Its derivatives—boric acid and borax, among others—command per-tonne prices well above those of more commoditized products.

Unlike potassium, boron is a niche market, smaller in volume but with attractive margins. The key lies in the quality and purity of the final product, which determines the accessible market segment. For operators with regional experience in borates, integrating this stream can represent a concrete competitive advantage.

Magnesium: From Technical Problem to Opportunity

Magnesium occupies an ambivalent place in brine processing. A high magnesium-to-lithium ratio raises costs and complicates production, since its removal requires reagents and generates waste. Much of the operating cost of many projects is explained precisely by the treatment of this element. For this reason, it has historically been viewed as a liability rather than an asset.

Nevertheless, the removed magnesium can be turned into marketable products such as magnesium hydroxide or chloride, with uses in construction, water treatment and industrial applications. Transforming a process residue into a revenue stream not only improves economics but also reduces the volume of waste and contributes to a more sustainable operating profile.

The Impact on Project Economics

The recovery of co-products and by-products directly affects central indicators such as the net cost of lithium production. When revenues from potassium, boron or magnesium are credited against operating costs, the effective cost per tonne of lithium carbonate equivalent can fall perceptibly, improving the project's position on the global cost curve.

This diversification logic also reduces exposure to a single market. A project that depends exclusively on the lithium price is at the mercy of its cycle; one that integrates several revenue streams gains stability. The trade-off is complexity: each additional line requires investment, specific technical capabilities and access to differentiated markets, so the decision must rest on rigorous feasibility studies.

Technological and Scale Considerations

Not every project justifies recovering every element. Viability depends on the specific concentrations of each salar, the scale of production, available infrastructure and logistics to target markets. Direct lithium extraction technologies, in particular, are reshaping these analyses, since they alter process flows and, with them, the way the remaining elements are separated and valorized.

Early planning is decisive. Designing a plant that contemplates by-product recovery from the outset is usually far more efficient than retrofitting facilities conceived solely for lithium. That is why a comprehensive assessment of the resource should be part of the conceptual engineering of any project aiming to maximize its value.

The Opportunity for Argentina's Puna

Argentina, consolidated as the world's fifth-largest lithium producer and endowed with low-cost brines in the Puna, is well positioned to capitalize on this diversification logic. The region combines favorable geology, a borate tradition and an investment incentive framework—such as the RIGI in force since 2024—that can encourage projects with a long-term vision and value integration.

Viewing brine as a polymetallic resource, and not merely as lithium, allows for envisioning more robust production hubs, with greater generation of skilled employment, local industrial linkages and an economy less vulnerable to the swings of a single commodity. In the context of a global energy transition, harnessing the potassium, boron and magnesium of the Puna is a concrete way to add value and strengthen the competitiveness of Argentine lithium.