Prilling/Melt Spraying
Examples of materials that have been successfully processed this way include low molecular weight polymers, phytosterols, waxes, fats, hydrogenated vegetable oils, and hydrated salts such as alum. While high melting materials such as metals, glasses and ceramics are routinely processed commercially, this requires special heaters and atomizing sources, so these materials are not typically processed on a toll basis. Materials that are easy to prill generally have melting points below 200 degrees C and melt viscosities lower than 200 cps.
Prilling offers a number of unique benefits in creating free-flowing powders from solids. First, prilling is a relatively inexpensive process for converting molten materials into a solid, easy to handle form. Second, the typical output consists of spherical particles, although the final form can vary from fibers (cotton candy is an example of the prilling of sugar, the melt viscosity of sugar is too high to form beads, but fibers are readily formed) to rods to spheres depending on the melt viscosity. Third, a wide range of final sizes are possible depending on the atomization method and the starting material. A particle size output of 10 to 3,000 microns is readily obtainable. Fourth, throughputs of 2,000 lbs/hour and higher with the above size distribution are easy to obtain. Finally, the process can be used with blended materials very easily.
Additives such as graphite, pigments, oils, other polymers, drugs, flavors and fragrances can be added to the melt to create unique beads. In this type of prill, the additive is encapsulated to some extent in the matrix of the wax, and the additive is somewhat protected from the environment. With the wide range of matrix materials and additives, prilling has found uses in the food industry as an additive delivery system or for taste masking, in the cosmetic industry for emollients and exfoliants, in the feed industry for fish oil and micronutrients, and in the chemical industry for lubricant and fragrance delivery.
Organogel Encapsulation
From our experience in prilling, AVEKA has developed innovative Gel Beads. These patented beads can be formulated to deliver active ingredients and create a stunning visual appeal when suspended in a viscous fluid. Unlike most prilled wax beads, Gel Beads can be easily rubbed out allowing them to deliver up to 95% oil without leaving any residue. To make the beads, a gelling agent such as microcrystalline wax, hydrogenated vegetable oils or carnuba wax is added to the oil of interest. This mixture is heated to form a solution and then prilled. The gelling agent precipitates from the cooling oil and forms a matrix structure within the oil. An SEM micrograph of the gelling agent structure in this unique biphasic bead is shown in Figure I. In a food system, formulated with food grade oils and gelling agents, Gel Beads have a unique soft “mouth feel.” The 200 to 1000 micron diameter beads can be colored or pearlescent, suspended in oils or aqueous solutions and carry oil loads previously impossible to attain. Common actives used in this technology include: oils, tocopherol (Vitamin E), Vitamin K, and pigments. Gel Beads are ideal for cosmetic, pharmaceutical, and food applications.
At AVEKA, a number of other unique methods have been developed from the basic prilling technology. For instance, a patent pending method produces beads with a fairly tight size distribution anywhere from 100 to 1,000 microns in diameter. Another method forms beads that incorporate 5-30 weight percent aqueous solutions in the wax matrix. A third technique produces a core/shell capsule with a wax shell surrounding an aqueous center. These beads are 300 microns to 2 mm in diameter with a 25-80% fill amount by weight.
Prilling Equipment
AVEKA Inc is equipped to produce research size samples from one to thousands of pounds in our Woodbury, Minnesota facility.
At AVEKA Manufacturing, our large-scale manufacturing plant in Fredericksburg, Iowa, we can produce 500-100,000 pound lot sizes of prills that are suitable for industrial, animal feed and personal care applications.
Finally, Cresco Food Technologies, LLC, is equipped to produce food grade prills under Circle U Kosher and Organic certifications in 500-100,000 pound lot sizes.