by Christian Schmalz, MBA Marketing Director, UlexAndes-USA
Fertilizer manufacturers, distributors and suppliers apply coating agents on dry fertilizer to prevent caking and reduce dust. For fifty-plus years the only anti-caking/dusting products available were petroleum-based products or ineffective mineral oils. GreenCoat products were formulated to solve this issue by using free-flowing, vegetable-based oils. Many fertilizer manufacturers, distributors and suppliers compete in an industry that is greatly impacted by technological improvements. Planting seasons across the country are reduced as technological changes impacted by advanced mathematics and equipment automation, air and soil sensors systems, and variable rate swath control are placing stricter tolerances on fertilizer quality.
It is the responsibility of the manufacturer to ensure customers receive a quality fertilizer. Not only should they meet expected nutrient requirements, physical quality standards should ensure free-flowing, dust free and no hygroscopicity. In addition, physical quality impacts factory economics both directly and indirectly when factoring in down time, recycling, reprocessing, rejections and possibly regulatory penalties. Common challenges faced by fertilizer manufacturing and production involve caking and dust production issues.
Today’s air spreaders and custom, variable rate applicators require premium quality dry fertilizers in their bins. Increased use of imported fertilizer and off-season fill programs create special handling requirements of dry fertilizers that can create quality issues.
When air tubes get clogged or hoppers and spinner blades need to be cleaned out, this creates expensive downtime. For only a few dollars/ton, suppliers can provide improved quality fertilizers to their customers, using coatings that are based on green technology and environmentally friendly. GreenCoat products are engineered for specific fertilizers such as: Urea, DAP, MAP, Potash and AMS.
Most fertilizers tend to form lumps or ‘caking’ during storage due to formation of contact points between the particles. It is commonly believed that crystal bridges forming at these points causes the most trouble. Weak Van der Waals forces resulting in capillary adhesion can also occur depending on the plasticity of the particles and the pressure exerted on the fertilizer.
The severity of caking is influenced by internal and external factors, including chemical composition, mechanical strength, moisture content, ambient conditions and storage time. The biggest impact is obviously the presence of moisture. The extent of drying varies widely with fertilizer manufacturing. Chemical composition also plays a part in the caking tendency of the fertilizer. For example, urea-based NPK products is much greater than ammonium sulfate-based NPK.
Particle size and shape also impact caking. Larger, well-formed and uniformity fertilizers minimizing fine material reduces the forces of attraction, lowering the caking tendency. Particle hardness influences caking as well. Weaker granules break down into fines under stacking pressure or with repeated handling resulting in caking due to the increased contact points between particles. Higher temperatures and humidity can cause severe caking problems. GreenCoat anti-caking agents utilizes Green Technology to adhere to the particle/granule/prill/powder to improve process control and storage/packaging conditions in an efficient, soil friendly way.
Dust Suppression Equipment
Along with GreenCoat anti-dusting agents, dust suppression systems are in high demand. With help of a dust suppression system, dust can be easily suppressed before it becomes air borne. Dust suppression systems consist of a series of nozzles that discharge the anti-dusting agents in a fine spray which reducing the amount of airborne dust particles during the fertilizer manufacturing process. This system can be used at any time for handling the bulk material wherever dust is resulting as a hazard.
There are several advantages of using dust suppression systems, including flexible system configurations, simplified maintenance and ease of installation. In fact, the investment of overall capital, as well as operating costs, are even more affordable than the cost of large plant production changes. Dust suppression systems have proven they can significantly reduce dust from a variety of fertilizer manufacturing equipment including crushers, screen, tippers, conveyor points and many more.
The storage and handling of bulk materials invites unique problems pertaining to dust formation in addition to caking. In the fertilizer industry, this problem not only causes waste, potential safety, environmental, and health hazards are associated with it. Phosphate fertilizers are commonly manufactured in powder, crystalline or granular forms and tend t
o either cake or break into dust. Fertilizer dust particles are small and light enough to be transported even by weak air currents. This dust could create numerous problems associated with environmental compliance and worker safety, increased productivity costs and high equipment maintenance and repair costs. Furthermore, the generation of dust in fertilizers tends to increase over time and is intensified by persistent storage posing spontaneous combustion risks. Spontaneous combustion is problematic because it relates to both the processing temperature of fertilizers and the storage temperature of the finished products.
UREA, a granule or prilled fertilizer has a very smooth surface, creating challenges for a suitable anti-caking/anti-dusting agent. GreenCoat’s polymer coating for urea acts on surface tension to bind the urea preventing caking and dusting.
Green technology implies the application of knowledge to develop techniques and methods that have the smallest impact on the environment. Usage of petroleum-based products as anti-caking/dusting agents on fertilizer indirectly increase the concentration of these products in the soil. By using vegetable originated ingredients, GreenCoat products minimizes this negative impact while providing a cost-effective alternative. When compared with mineral oil, vegetable-based products reduced the dust by more than 40% in very porous granules of MAP, TSP and DAP. Because vegetable-based coatings stick to the surface and aren’t absorbed, they required lower application rates with a longer duration of action.