Reto Steiner, Emile Egger and Cie SA explain how a closed-loop model helps scale circular potassium sulfate production
In the face of increasing regulatory and environmental pressure, the global fertiliser industry is accelerating its transition toward sustainable manufacturing models.
Among the new generation of innovators, Swedish startup Cinis Fertiliser, a green plant nutrition company, has gained attention for its pioneering approach to circular potassium sulfate (K2SO4) production. By upcycling industrial residues into high-purity fertiliser using a process powered entirely by renewable electricity, Cinis presents a new benchmark in green mineral production.
At the heart of this solution is an integrated system of robust process equipment, including advanced axial flow pumps supplied by Egger Pumps and thermal crystallisation technology engineered by Evatherm. This particular collaboration exemplifies how tailored process engineering can enable scalable, low-impact chemical production.
A circular production model for potassium sulfate
Cinis Fertiliser’s patented process is built on the principle of circular resource use. Rather than relying on virgin raw materials or fossil-intensive production routes, Cinis recovers potassium-rich and sulfate-rich waste streams from industries such as pulp and paper (sodium sulfate), and bioenergy (potash-containing fly ash). These byproducts, traditionally regarded as waste and often landfilled or discharged, become the core feedstocks in a reaction and crystallisation process yielding high-purity K2SO4.
The company’s first industrial site, located in Örnsköldsvik, Sweden, is fully electrified with energy sourced from renewables and features a closed water loop. The design ensures minimal impact on surrounding ecosystems while supporting long-term operating efficiency. According to Cinis, their method results in more than 90% reduction in carbon footprint compared with conventional processes like Mannheim furnace technology, which involves sulfuric acid and potassium chloride combustion.
How the Cinis models Compares to other fertilisers and waste streams
A key question for process engineers and industrial chemists is whether Cinis’ approach can be generalised or transferred to other fertiliser types or sectors generating high-salinity waste. The answer is conditionally yes—but only under certain technical and economic conditions.
The underlying concept of Cinis’ model is ion substitution followed by thermal crystallisation, using low-grade industrial byproducts with known and stable compositions. This framework may be adapted to produce other sulfate-based or even nitrate-based fertilisers if certain criteria are met:
• Presence of concentrated, chemically consistent waste streams: Just as Cinis relies on predictable sodium sulfate and ash byproducts, other applications must secure feedstocks with defined compositions and limited impurities to enable stable crystallisation.
• Thermodynamic compatibility: The targeted fertiliser salt must have solubility and thermal properties that allow efficient separation and recovery at scale using either cooling or evaporative crystallisation methods.
• Regulatory acceptance of byproduct use: agricultural-grade fertilisers require tight control over contaminant levels (e.g., heavy metals). Adapting the model to other streams (e.g., phosphogypsum, desalination brines, lithium extraction residues) would necessitate additional purification stages, impacting feasibility.
• Market alignment: As with K2SO4, the target compound should have strong demand, preferably for crops requiring specialised nutrition (e.g., chloride-sensitive crops), to justify the investment in process adaptation.
In practice, extensions of this model are being explored. Other process engineering firms are following similar paths in upcycling desalination brines into magnesium fertilisers or recovering ammonium salts from industrial scrubbers.
While each case requires unique adjustments in process chemistry, separation design, and equipment selection, the core vision—converting industrial waste into plant nutrition—is broadly transferable. The challenge lies in scaling these systems while ensuring cost parity and environmental compliance.
How Egger pumps achieve scalable flow control
To support its high-throughput and low-impact production strategy, Cinis specified axial flow pumps from Egger Pumps for their fluid transport needs. The startup integrated eight elbow propeller pumps, selected for their ability to deliver large volumes of corrosive slurry and solution with minimal energy input.
The elbow design of the Egger pumps allows for tight installation layouts while maintaining efficient axial flow performance. These pumps are engineered to withstand highly alkaline, sulfate-rich process fluids, offering reliable suction characteristics and smooth hydraulic behavior. This results in improved process stability across the multi-step reaction, separation, and crystallisation phases.
Thanks to their robust construction and corrosion-resistant materials, the pumps require minimal maintenance and are ideal for 24/7 operation in closed-loop systems. Their high efficiency further supports the energy objectives of the all-electric plant.
Integrated design with Evatherm crystallisation systems
Cinis’ process is made possible through collaboration with Evatherm, a Swiss specialist in evaporation and crystallisation. The process configuration includes:
• Concentration stages to achieve optimal supersaturation
• Controlled cooling and crystallization for selective salt recovery
• Efficient separation and drying systems to ensure fertilizer purity
Integration of Egger Pumps within Evatherm’s crystallisation design ensures that material flow rates and compositions remain consistent, which is crucial for maintaining crystal morphology and product quality.
Outlook: redefining fertiliser sustainability
By rethinking how fertilisers are produced—shifting from extraction to upcycling—Cinis Fertiliser is demonstrating that sustainability in chemical manufacturing can be technically rigorous and commercially interesting.
With reliable equipment partners like Egger and Evatherm, the company has constructed a modular, scalable solution for clean potassium sulfate production.
If successfully adapted, this model could inspire similar efforts in nitrate, phosphate, or micronutrient fertiliser production, particularly in regions with significant industrial waste streams and access to renewable energy.
For more information visit: www.eggerpumps.com
