Unlocking Indonesia’s Nickel Tailing Potential via CCUS: Turning Hazardous Slurry into Carbon-Negative Concrete

Indonesia stands at the forefront of the global energy transition—not merely as a participant, but as a dominant force. With approximately 55 million metric tons of nickel reserves, accounting for around 42% of global supply, and contributing nearly 50% of worldwide production (USGS, 2024), the country has established itself as the world’s nickel superpower. This geological advantage is rooted in Indonesia’s extensive lateritic nickel deposits, formed through prolonged weathering of ultramafic rocks in tropical environments.

However, this dominance comes with a critical challenge. Nickel is a key material for electric vehicle (EV) batteries and other clean energy technologies, yet its extraction produces vast quantities of waste. For every ton of nickel produced, several tons of mine tailings—fine-grained, slurry-like residues—are generated. These tailings accumulate rapidly, require long-term management, and pose environmental risks if left untreated. This creates a fundamental paradox: a material essential for enabling decarbonization is simultaneously generating a new environmental burden.

To better understand this issue, it is important to examine the structure of Indonesia’s nickel deposits. These lateritic systems are typically divided into two main layers: limonite and saprolite. The limonite layer, located near the surface, is iron-rich and contains relatively low nickel concentrations, making it suitable for hydrometallurgical processing such as High-Pressure Acid Leaching (HPAL) to produce battery-grade materials. Beneath it lies the saprolite layer, which is richer in magnesium and contains higher nickel grades, making it more suitable for pyrometallurgical processes used in stainless steel production. While both layers are economically valuable, their extraction inevitably generates large volumes of residual tailings.

Figure 1. Nickel Laterite Soil Profile

Traditionally, these tailings have been treated as waste and stored in containment facilities. However, emerging research suggests a transformative opportunity: nickel tailings can serve as a reactive medium for carbon capture, utilization, and storage (CCUS). Rather than being an environmental liability, they can be reimagined as a resource capable of permanently binding carbon dioxide (CO₂).

At the core of this opportunity lies the mineral composition of the tailings themselves. Nickel tailings are rich in magnesium silicate minerals, including serpentine, olivine, and brucite. These minerals are naturally alkaline and thermodynamically unstable in the presence of CO₂, meaning they have a strong tendency to react with CO₂ and form stable carbonate minerals. This process, known as mineral carbonation, provides a pathway for permanent carbon sequestration.

The capacity of nickel tailings to sequester carbon is fundamentally governed by their mineralogical composition, which is dominated by magnesium-bearing silicates such as serpentine (Mg₃Si₂O₅(OH)₄), olivine (Mg₂SiO₄), and brucite (Mg(OH)₂). These minerals are inherently alkaline and thermodynamically unstable in the presence of CO₂, making them highly reactive toward carbonation reactions. Mineral carbonation is a multi-step geochemical process involving dissolution, ion release, and precipitation, ultimately converting gaseous CO₂ into stable solid carbonates.

Figure 2. Integrated CCUS–Nickel Tailings System

The process begins with the dissolution of carbon dioxide into water, forming carbonic acid:

CO₂ (g)+H₂O (l)→H₂CO₃ (aq)

Although carbonic acid is weak, it plays a critical role as a reactive agent that initiates the breakdown of silicate minerals. The acid dissociates to release hydrogen ions, which attack the crystal lattice of magnesium silicates. For example, in serpentine:

Mg₃Si₂O₅(OH)₄ (s)+6H⁺ (aq)→3Mg²⁺ (aq)+2SiO₂ (s)+5H₂O (l)

This dissolution step is typically the rate-limiting stage of the process, as it involves breaking strong chemical bonds within the mineral structure. The reaction releases magnesium ions (Mg²⁺) into solution while producing silica, often in an amorphous form.

Simultaneously, dissolved CO₂ equilibrates in solution to form carbonate ions. These carbonate ions then react with magnesium ions to form solid carbonate minerals:

Mg²⁺ (aq)+CO₃²⁻ (aq)→MgCO₃ (s)

Depending on reaction conditions such as temperature, pressure, and water availability, different carbonate phases may form, including nesquehonite, hydromagnesite, and magnesite. Over time, less stable hydrated forms can transform into more stable anhydrous phases, such as magnesite, which is capable of storing carbon over geological timescales.

This final stabilization step is what makes mineral carbonation particularly attractive as a carbon storage solution. Unlike conventional carbon capture methods that rely on underground storage, this process chemically binds CO₂ into solid minerals, eliminating the risk of leakage and significantly reducing the need for long-term monitoring.

The integration of CCUS with nickel tailings creates a seamless process chain. CO₂ emissions from industrial sources—such as power plants, smelters, and cement factories—are first captured using technologies like post-combustion capture or direct air capture. The captured CO₂ is then purified, dehydrated, and compressed before being transported to tailing processing sites. There, it reacts with tailings in a controlled carbonation system, producing solid carbonate minerals and silica.

Importantly, the outputs of this process are not merely waste products but valuable materials. The carbonate minerals formed during carbonation can function as binders or fillers in construction applications. In parallel, the silica produced can act as a supplementary cementitious material (SCM), reacting with calcium hydroxide in cement to improve strength and durability. Studies have shown that replacing 5–15% of cement with reactive silica can enhance compressive strength while reducing overall emissions.

This is particularly significant given that cement production accounts for approximately 8% of global CO₂ emissions. By partially substituting cement with carbonation-derived materials, the process not only stores carbon but also reduces emissions at the point of material use. In effect, carbon is not just captured—it is embedded within the built environment.

The result is a rare “3-in-1” solution: permanent carbon sequestration, waste valorization, and low-carbon material production within a single integrated system. This approach aligns closely with Indonesia’s resource profile, leveraging its abundant nickel tailings as a feedstock for scalable CCUS applications.

Nevertheless, several challenges remain. The implementation of such systems requires substantial initial capital investment for capture infrastructure, reactors, and material processing facilities. Variability in tailings composition can also affect reaction efficiency and product consistency. In addition, regulatory frameworks for carbonated construction materials are still evolving, posing challenges for certification and market adoption. Logistical considerations, including CO₂ transport and integration with existing mining operations, further add to the complexity.

Despite these barriers, the potential benefits are significant. With strategic investment, supportive policy frameworks, and continued technological development, CCUS-based mineral carbonation could become a cornerstone of sustainable mining in Indonesia.

Ultimately, Indonesia’s position as the world’s leading nickel producer presents not only an economic opportunity but also a strategic responsibility. By transforming nickel tailings from an environmental liability into a carbon-negative resource, Indonesia has the potential to lead a new paradigm in industrial sustainability—one where resource extraction, carbon management, and material innovation are fully integrated.

References

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Kementerian Energi dan Sumber Daya Mineral (ESDM). (2023). Peluang Investasi Nikel Indonesia 2023. Direktorat Jenderal Mineral dan Batubara.

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Ofori, K. A., Hanson, W., Huang, K., Amankwaa, V., Handler, R., Stacey, D., & Pan, L. (2025). Technical feasibility, technoeconomic, and life cycle assessment of CO2 sequestration using domestic nickel mine tailings: A direct ex-situ hydrothermal approach. Journal of Cleaner Production, 532, 146957. https://doi.org/10.1016/j.jclepro.2025.146957

Davraz & Gunduz (2005). Cement and Concrete Research.

Shanks, B., Howe, C., Draper, S., Wong, H., & Cheeseman, C. (2024). Carbon capture and storage in low-carbon concrete using products derived from olivine. Royal Society Open Science, 11(5), 231645.