Prior to the development of the Mikro LGM® Long Gap Mill, materials had to be dried and de-agglomerated in two separate operations. For example, a rotary drum dryer was used to dry materials that had been wet milled. A separate grinding/de-agglomeration process followed the drying operation. The Mikro LGM® Long Gap Mill is Hosokawa's solution for streamlining these two operations into one continuous process. This type of dryer is commonly referred to as a "gap" type mill. It is called a "long" gap mill because of the long annular gap path the process material takes from the inlet to the discharge. By combining several operations such as flash drying, de-agglomeration and surface coating into one operation, a Mikro LGM® Long Gap Mill eliminates the need for multiple material handling systems which subsequently increases process efficiencies. The dried powders often do not require any further size reduction. Both slurries and wet cake can be handled.
The Mikro LGM® Long Gap Mill modular design expands its range of applications beyond drying and deagglomeration. For dry grinding, modular options include: direct and independent drive classifiers; pre-grind rotor stage; an integrated jet mill and variable stage rotor design. The smaller size Mikro LGM® Long Gap Mills are engineered with a split body housing for easy maintenance and cleaning. The LGM processes high moisture materials in wet cake form as well as dry solid feed stocks up to one inch. Finished product particle sizes of D97 < 10 microns can be achieved.
The Mikro LGM® Long Gap Mill has demonstrated superior performance over all other mechanical mills in reducing grit from pre-sized and agglomerated powders. Typical results are less than 1 part per million (ppm) residue on a 44 micron sieve starting from a feed stock with a residue of 120 ppm.
This performance is achieved with a powerful grinding mechanism coupled with a precision internal air classifier. The air classifier is designed for a theoretical cut point of 2-5 microns, depending on the particle density. Rejected particles are forced away from the classifier wheel and redirected outside of the mill back to the material inlet using a patented re-circulation system.