The Problem

Engineers at Martin Marietta Magnesia Specialties, Inc. were in the process of designing two steel silos to handle dolomite lime at one of their plants. We were asked to evaluate the proposed design to determine whether mass flow would be achieved, which was required in order to minimize segregation and ensure reliable flow. We received representative samples of dolomite lime from Martin Marietta, and performed flow property tests. The test results showed that this dolomite lime was easy flowing, and thus able to flow through small outlets without forming a cohesive arch. However, it was also very frictional, requiring steep hopper angles.

Jenike & Johanson's Solution

The solution we recommended incorporated a unique BINSERT® design. We took the normal cone-in-cone concept one step further with the addition of an internal third cone. In doing so, we were able to utilize the original hopper envelope, thus maintaining the required silo capacity within the same height.

With a BINSERT® system, segregation can be controlled better than with a mass flow silo with a single cone. The BINSERT® system reduces solids velocity differences, thereby virtually eliminating segregation regardless of the material level in the cylinder.

The Result

After Martin Marietta put the silos into service. R. M. Racey Jr., Senior Staff Engineer at Martin Marietta, wrote in an unsolicited letter "I want to thank you for the design work your firm provided us on our lime storage silo project. We are pleased that the silos function as intended and all of the equipment is working well."

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