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Alumina is a fine powder that is used in the manufacture of aluminum, abrasives, refractories and various household products. Large users of alumina often arrange to have it shipped to their plants in 100 ton railcars. The quality and consistency of the alumina, which can vary within each railcar and from one railcar to another, can affect a manufacturing process which uses a lot of alumina. Some processes can detect and compensate for gradual changes without any significant loss of product quality. However, rapid changes may result in a significant loss of finished product because of unacceptable variations.
The Problem
At a plant operated by one of Jenike & Johanson's clients, a pneumatic line conveys alumina from railcars to a 12 ft. diameter storage bin. This bin was originally designed for mass flow, but the resulting first-in-first-out flow pattern caused the abrupt variations between and within railcars to be passed on to the process. Our client wanted to blend the alumina in order to smooth out these variations. The logical place to do this was in this bin.
The Solution
Jenike & Johanson engineers studied the blending requirements and recommended modifying the bin to incorporate a BINSERT® blender. We then built and tested a scale model of the blender. The results convinced us and our client that this change would cause the alumina to be blended to reduce the process variation.
We performed structural calculations and designed the necessary modifications to incorporate a BINSERT® blender in the conical hopper section. Next we arranged for fabrication of the new hoppers and supports. To ensure quality control, our engineers made frequent visits to the fabricator's shop.
The Result
This BINSERT® system has now been in operation for several years, providing continuous blending of the alumina. As a result, the rejection rate due to variation in finished products has improved significantly. This dramatic improvement was achieved at a cost of only the BINSERT® system retrofit to the existing bin. There are no additional operating costs.
