The potassium sulfate (SOP) fertilizer market is continuing on a growth trajectory and is anticipated to see a CAGR of 5.16% between 2020 and 2027. The alternative to potassium chloride (MOP) has gained a foothold in agriculture as a premium product for high-value and chloride-sensitive crops, as well as a source of sulfur.
One common way in which fertilizer producers bring potassium sulfate to market is in a granular form produced through the wet granulation process. And as the number of producers looking to granulate their potassium sulfate (SOP) continues to rise, feasibility testing and process development services are in ever-higher demand; producers are discovering that this novel source of potash requires thorough testing and development to bring a successful SOP granulation operation online.
Here’s a look at why testing is so important when it comes to granulating SOP fertilizers, and how producers are utilizing the FEECO Innovation Center to develop their commercial-scale operations.
Why Wet Granulation for SOP?
Wet granulation, also known as agitation agglomeration, pelletizing, or tumble-growth agglomeration, is just one way to produce an SOP fertilizer product. SOP may also go to market in the form of powder, crystals, or compaction granules. So why wet granulation?
Wet granulation produces a rounded fertilizer granule, which has numerous benefits over other forms of SOP, including reduced dust, improved flowability and spreading, enhanced coating potential, and more. All of these qualities make a fertilizer produced via wet granulation considered a premium product. But one of the biggest reasons for choosing this type of granulation is that it gives producers a much greater ability to control particle characteristics.
As part of producing a premium product, many producers are looking to control particle characteristics to manage the look, handling, and performance qualities of their product; wet granulation enables this.
Potassium sulfate granules produced via wet granulation in the FEECO Innovation Center
Why Potassium Sulfate (SOP) Granulation Testing is So Critical
Feasibility testing and process development are often recommended when it comes to granulating materials, but testing is especially important for potassium sulfate for several reasons.
A Novel Fertilizer
First and foremost, despite not being a newly discovered material, interest in using SOP as a fertilizer is fairly new. Compared to mature fertilizers such as MOP, DAP, or NPK, the production of potassium sulfate as a fertilizer product is not quite as well established.
While significant work around the properties of SOP and its behavior in a process setting has been carried out, there is still much work to be done. Testing gives producers the opportunity to establish a baseline of data around their material, determine basic process parameters, and bring to light any potential challenges the material may present in a commercial-scale setting. Testing is therefore vital to designing a commercial-scale plant that reliably operates at its rated capacity and yields product of the desired quality.
To Establish Process Parameters
Testing is also necessary to gather process data such as feed rates, retention times, equipment speed, binder spray locations, temperature profiles (in the case of drying), and much more. Ultimately, testing reveals the “recipe” of process variables necessary to produce a product that meets quality expectations and process criteria.
Variation in SOP Sources
Granulating SOP is further complicated by the multiple avenues through which it can be produced. Each approach, and variation of approach, as well as the starting material inputs, can yield different characteristics in the final SOP. This might include variations in:
- Particle size distribution
- Chemical composition
- Bulk density
- Moisture content
- Hardness
- Rheology
- And more…
This diversity makes each source of SOP unique, further necessitating testing to establish baseline and advanced process data.
To Assess Different Binders
Binder selection is a critical aspect of the granulation process. With various binders available, producers must select a binder that not only facilitates granule formation and growth, but that also provides the desired characteristics in the finished product.
Binders can also be selected to impart nutritive value or other beneficial qualities to the product. Testing therefore is vital to determine which binder provides the best fit based on process and product goals.
A sample of SOP granules is evaluated during testing in the FEECO Innovation Center
SOP Granulation Testing Capabilities
The FEECO Innovation Center offers several options for testing SOP granulation. In broad terms, the Innovation Center can:
- Confirm feasibility
- Show proof of concept
- Establish proof of product
- Illustrate proof of process
When testing on a continuous basis, the Innovation Center is also able to provide producers with information on process stability, bottlenecks, power requirements, and even emissions.
Depending on what stage a project is in, what is known about the material, and what the project goals are, testing can be conducted at batch or pilot scale, on a single piece of equipment or as a continuous process loop with drying and recycle. Key equipment available for testing includes:
- Rotary Drum Granulator
- Coating Drum
- Disc Pelletizers
- Pin Mixers
- Pugmill Mixers
- Rotary Dryer
- Various support equipment (feeding, conveying, etc.)
In addition to having the right equipment and infrastructure, the Innovation Center is uniquely positioned to assist SOP producers from an expertise point of view as well, with an extensive background in the fertilizer industry. Since 1951, FEECO has been on the front lines of both traditional and specialty fertilizer production development and has become a preferred provider to the potash industry for testing and development services, custom equipment, and parts and service support.
Conclusion
As SOP gains more market share, the importance of feasibility testing and process development services will continue to grow as producers work to establish standards for the product, and explore specialty formulations and treatments.
With unmatched experience and comprehensive testing capabilities, the FEECO Innovation Center provides the ideal environment for testing SOP wet granulation at every stage from batch to continuous pilot scale. For more information, or to schedule a test, contact us today!