Common salt (NaCl), like sugar, is considered to be a neutral powder and is used for dry cleaning of hygienically designed equipment and installations. Its own handling and treatment requires an equally hygienic equipment design to prevent its possible contamination during these processes. In addition, it is also necessary to take into account the product’s own considerations: highly corrosive and hygroscopic.
In its design, a number of specifications must be taken into account to reduce or eliminate the risk of the bucket elevator being a source of contamination for this product, both directly and indirectly. This is achieved by making the bucket elevator easy to clean, inspect and maintain, and by avoiding the generation of dirt in the bucket elevator design.
All materials in contact with the salt must be stable and inert. In this case, as it is a belt bucket elevator, the selection of the belt must comply with FDA requirements, as well as the rubber of the driving pulley, pulley blocks, gaskets, etc…
The contact surfaces inside the elevator must also be designed and constructed in such a way that they can be easily cleaned. For example, the internal angles and corners must be wide and rounded, and the foot and head of the hoist must include several manholes so that the entire interior of the hoist is accessible for a cleaning and inspection system. In addition, the joints between the different bodies of the lift must be sealed with FDA-certified putty to ensure that they are watertight and hygienic. With regard to the geared motor, we took the precaution of designing a basin to collect accidental oil spills, which was also used for foodstuffs, as well as the grease from the different bearings of the equipment.
SINFIMASA has manufactured for a major mining company two bucket elevators in 316L stainless steel in accordance with the principles of hygienic design as a key element for the prevention of contamination. These bucket elevators, each over 31 metres high, have a throughput of 30 tonnes. After installation, they were heat-insulated to prevent condensation from forming inside the elevators due to temperature differences.