Bulk material storage vessels (e.g., silos, bins, hoppers, elevators, bunkers) are available in a variety of sizes, shapes, and materials of construction. Proper selection of a silo, bin, or hopper requires evaluation of many factors, and in cases where basic material characteristics have been ignored, undesired consequences such as structural failures, caked or segregated material, and erratic discharge have resulted. Jenike & Johanson engineers excel at thoroughly reviewing your storage needs, measuring critical bulk material flow characteristics, selecting the appropriate hopper discharge pattern, and designing a storage vessel that will operate correctly from the start and provide a long service life.

The company’s designs consider:

  • general configuration that meets capacity and spatial constraints; 
  • bulk material flow properties that help select vessel design parameters; 
  • hopper shape, angle, and internal surface required for bin flow pattern; 
  • outlet size and shape engineered to avoid poor flow and ensure discharge rate;
  • feeder selection and design to maintain reliable discharge from hopper outlet; and 
  • unique design features for powder and bulk solids reliable handling, processing.

Jenike & Johanson’s experience has included work with:

  • converging/diverging mass flow silo for highly cohesive wet bran; 
  • mass flow purge column that efficiently strips polyolefin hydrocarbons; 
  • expanded flow silo retrofit for handling hot lime at 427ºC (800°F); 
  • diverging silo and apron feeder that handles saturated gold ore tailings; and 
  • air-assisted discharge silo for feeding kaolin clay at high rates into railcar.

Storage vessels are necessary for handling bulk materials in any industry. While contained, bulk solids are exposed to a variety of external factors that can cause problems for the equipment as well as its cargo. Jenike & Johanson is constantly working on projects that involve analysing a material in order to engineer a handling process that minimizes wear on the equipment. On one specific occasion, Jenike & Johanson helped reduce the hazards of shipping a bulk material by first testing its flow properties.

THE NEED

The Code for Safe Practice for Solid Bulk Cargoes provides rules of safe practice for the shipment of bulk cargos by ship. One of the rules is to ensure the materials in the holds have sufficient time to settle and are stable before proceeding out of port. Bulk cargo carriers have been known to list and even sink as a result of unstable cargo — especially in inclement weather.

The metal concentrate producer understood the risks and was aware of the concern. However the codes give no specific guidelines on how long to wait to ensure a fine, dry concentrate has properly settled and no longer presents a risk of being unstable. Waiting too long presents costly time lost at the port so there is substantial pressure to depart as quickly as possible. Therefore a thorough basis for determining a sufficient wait period was required.

THE SOLUTION

Jenike & Johanson was commissioned to study the problem and provide a reliable method for setting the wait period. Its approach was to measure the relevant flow properties of the metal concentrate. It then used Jenike & Johanson’s proprietary SETTLE software to predict how long the vessel must stay in the port before sailing to ensure the cargo is stable. This required an understanding of hold sizes, filling behaviour, and the flow properties of the material. For this client’s ships and filling approach, Jenike & Johanson recommended that the vessel remain in port for at least 24 hours after the last hold was filled.

THE RESULT

According to the client, there have been no reports of cargo shifts since adopting Jenike & Johanson’s recommendations. The project has eliminated the risk and provided an engineered approach for the required wait period before setting sail.

Jenike & Johanson has developed proven and practical ways to design powder and bulk solids storage, handling, and conveying equipment to promote reliable, uniform, and unrestricted bulk material flow. Its unique combination of science/engineering/ design capabilities and its engineering team with years of hands- on experience is unmatched by any other bulk material handling organization.

When faced with unique bulk material handling challenges, Jenike & Johanson prides itself on its ability to provide innovative equipment designs engineered for its clients’ challenging applications.