The Quest for Clean Mixing
Mixing is one of the most ubiquitous unit operations in the processing world. And oftentimes, improvements specific to the mixing step lead to overall big rewardsthat translate well in the balance sheet. The usual challenges include maintaining batch-to-batch uniformity and optimizing blend times, but could be as simple, yet equally important, as improving cleanliness. Below are some ways to lessen the mess and reduce health hazards in your mixing environment, categorized by applications.
DRY BLENDING AND DRYING APPLICATIONS
In a ribbon, paddle or vertical screw blender operation, sealing arrangements arekey to keeping clean. The blender doesn't necessarily have to be vacuum-rated, just dust-tight. Covers with Neoprene or Silicon gasket, clamps, vent ports with dust socks, dust-tight discharge valves, material handling system installed right at the blender's discharge assembly – all these contribute to eliminating fugitive dust issues. In addition, auxiliary dust collection systems and solvent recovery systems (for drying operations) may be used in conjunction with blending equipment.
Hydraulically or pneumatically operated lids are a common option in many horizontal blenders. They can be designed to support a full pallet of raw materials and may be installed with quick-release charging ports that can be oriented to different angles and adjusted to accept ingredients from drums, bags, or other containers.
Inside the blender, areas that present cleaning problems are stuffing boxes, corners and discharge arrangements. Surfaces of the trough interiors and the agitator should be polished to help eliminate material sticking, buildup, and product contamination. If powders are not particularly easy flowing, special ribbon or paddle agitator designs with scrapers and generous radius can prevent product from stagnating in the trough corners.
