For that is precisely what the technology promises to do. First introduced in the 1990s to encapsulate uranium for nuclear energy applications, the process enables a variety of different materials to be formed into perfectly round microspheres or encapsulated with a host of shell materials. According to John Imhoff, marketing manager for Harper International, the process reduces manufacturing costs, produces a narrow particle size distribution and improves quality compared to conventional processes.
"The elimination of high-pressure systems and moving parts reduces operating and maintenance costs while maximizing running time. The process forms the feed into spheres of uniform size and perfect roundness, yielding a high-quality product," he says.
The resulting spheres have a monodispersed grain size and a narrow size distribution (dmax/dmin œ 1.10, 1.05, 1.01). They are free flowing and roll with almost no friction or abrasion, thereby minimizing agglomeration and eliminating dust during material handling operations. The spheres can range in diameter from 50 to 6000 µm (6 mm), depending on the size requirements of the product, and can be modified through subsequent washing, additional chemical reactions, drying, calcining, sintering, coating or sorting processes.
"The technology's ability to produce small, uniform particles in smooth, perfectly round spheres is a significant benefit in many ceramic applications," says Imhoff. "Compared to conventional processes such as spray drying or dry pressing, the technology produces spheres with much higher densities and consumes significantly less energy, primarily because it's a much more efficient process. With spray drying, for instance, the material has to be first atomized and then dried at relatively high temperatures. It must then be screened, and much of the material typically has to be reprocessed to achieve the desired particle size. The BRACE-Process cuts out all of these extra steps. Additionally, spray drying produces small sized particles, there is often an accumulation of product in the drying chamber and ducts, and the density tends to be lower than what our process can achieve."
According to Imhoff, the technology can also eliminate the need for polishing steps that are sometimes required after dry pressing.
As users continue to experiment with the technology-both in Harper's laboratory and in their own pilot-plant installations-additional uses are likely to emerge.
"Ceramic materials are under-utilized in a number of areas because of the high expense and difficulty of getting a narrow particle size distribution and high yields of perfectly round spheres. The BRACE-Process can make these applications much more attractive and can help ceramic manufacturers gain a larger market share from metallic or other materials currently being used in these fields," Imhoff says. c
For More Information For more information about Harper's microsphere and encapsulation laboratory, or the BRACE-Process, contact Harper International Corp. at West Drullard Ave., Lancaster, NY 14086-1698; (716) 684-7400; fax (716) 684-7405; e-mail firstname.lastname@example.org; or visit www.harperintl.com.