Solving Costly Limestone Flow Problems at Titan Cement
The Problem
Titan manufactures cement at their Medley, Florida USA plant, and in 2004 commissioned a new 5,000 t per day kiln that greatly increased clinker production capability and efficiency. However, due to poor flowing raw materials handled in the new silos, large variations in raw meal properties resulted, principally from erratic flow of raw materials. Flow problems, such as bridging, ratholing, and segregation were occurring with the limestone, as well as other additives like bauxite and mill scale.
Jenike & Johanson's Solution
Jenike & Johanson engineers recommended to Titan that flow properties tests be performed on the limestone and other raw materials. We recommended to Titan that a mass flow pattern be implemented, which allows a first-in, first-out discharge that prevents ratholing, ensures consistent flow, eliminates sifting segregation, and reduces the loads on the apron feeder.
Analyses were also performed by Jenike & Johanson to determine material-induced and external loads (e.g., wind, seismic, etc.) on the silo and structure. Material-induced loads from initial fill and mass flow discharge scenarios were analyzed. Jenike & Johanson provided engineering designs to Titan for the arrangement/ installation of the hoppers’ liner panels as well as their connection details to the new cone and existing cylinder.
The Result
According to John Anagnostou, production manager at Titan, the modified silo has provided reliable, consistent flow of the limestone, even when handling moist, fine material. Since the modifications, mass flow has been achieved which has eliminated the costly bridging, ratholing, and segregation problems. The apron feeder has worked well, and the weigh belt feeder/clean-up conveyor system has allowed fine-tuned control of the raw mix chemistry. Not only were critical details for flow supplied, but also, engineering specifications for demolition, scaffolding, installation, and fabrication were provided to Titan in a complete drawing package. The efforts, in part, allowed Titan to eventually exceed design clinker production capacity by 10%.
