Molasses Handling & Storage

Correct specification of tanks, pipework, pumps, metering systems and mixers are key to ease of molasses handling and application within the feed mill.

Storage and Distribution

  • Receiving tanks should be of the correct capacity and easily assessable
  • Pipe layout should not negatively impact molasses flow
  • The importance of temperature can’t be underestimated


Metering and Pumping


  • A positive displacement pump is best for molasses distribution
  • Positioning of distribution pumps is key to correct application

Molasses Inclusion and Mixing


  • Molasses viscosity impacts mixing times
  • Application of molasses can occur at 2-3 different stages
  • Molasses application to course rations works off a different principle than that applied to meals.
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Molasses can be stored for long periods without deterioration provided no dilution of the liquid feed occurs. Feed mill storage tanks should be located so they are easily assessable by truck, and of a capacity suitable for the mills size or capable of holding a minimum of 35 tonnes. Tanks, should be constructed from mild steel or plastic and be of a standard that can receive liquid with a specific gravity (SG) of at least 1.4. Incorporating a tank vent (preferably swan neck) into the tank design will prevent any accumulation of surface condensation.

Receiving tank inlet pipework ideally requires a female connection and be of a diameter of no less than 75mm (3”). This pipework should be easily assessable and securely fixed at a level of approx. 750mm above ground. Mild steel is generally the material of choice for external and internal pipework but polyethylene or PVC piping is also satisfactory for internal molasses distribution. Pipe layout within the mill should allow for a minimal number of directional changes and where possible 90° bends should be avoided.

The use of one or more heated constant header tanks (day tanks) is desirable for mill distribution systems. Header tank capacity should be sufficient to service four hours of feed mill production. Additionally, heating these tanks to a constant temperature of 25-30°c will allow for a more uniform molasses application regardless of origin and viscosity. Flow regulation can occur via electronic level controls. The positioning of these control sensors is important, and should allow for a continuous molasses feed to enter the header tank, therefore, preventing any reduction in the overall tank temperature.

Providing a well-designed molasses distribution system will allow for consistent metering and proportioning. For reliability, molasses flow must be capable of positive regulation. Incorporating a metering pump directly below the header tank will best facilitate this. Frequent checking of the metering system is required to ensure consistent molasses inclusion levels.

Under specification of pumps and distribution pipework are the main causes of molasses handling difficulties within the feed mill or block manufacturing plant. When choosing a distribution pump, it is important to note that centrifugal pumps are not suitable for molasses circulation. Positive displacement pumps will work however, with the following list being best in practice:

– Rotary Lobe.

– Gear.

– Stator/Rotor.

– Sliding Vane

Distribution pumps should be located adjacent to the supply tank and preferably allow for a gravity feed. The pump inlet pipework should be of a larger diameter than the outlet and preferably not less than 75mm (3″). The speed of molasses pumps should normally be in the range of 100 to 300 rpm. Variable speed metering pumps should have a low-speed facility for minor inclusion levels. Pumps should be equipped with a spring-loaded pressure relief valve which may be augmented with a manual by-pass valve where required.

Through the selection of the appropriate mixing and inclusion methods, greater molasses inclusion levels can be accurately included into compound feeds. Even at low molasses inclusion levels, feed pellet quality greatly increases. Molasses has proved to be very effective as an aid to reducing inherent dust in meals and improving product outflow flow from storage bins.

To achieve good molasses inclusion levels with standard milling equipment, it is essential to be aware of two basic rules:

  1. Use a good mechanical mixer to blend the molasses and meal together to guarantee every particle of meal is coated.
  2. The higher the viscosity of molasses, the thicker the coating will be and the more time is required for absorption. When looking at the absorption process the following key factors need to be considered:
  • Meal particle size, smaller particles will have a quicker absorption time.
  • Inclusion level, the higher the proportion of molasses the greater the time required.
  • Simultaneous addition of high levels of oil, fat or water will slow molasses incorporation.
  • The meal must be dry enough to accept the formulated level of molasses.



With many conventional milling systems, it is possible to add molasses to the meal at two or three stages during the production process. Initially, up to 2% molasses can be added to the meal at the main mixer, with this been achieved through injecting molasses at a controlled rate into the lower half of the horizontal mixer (unlike fat and other liquids that are added from the top). This allows for maximum absorption time. Additionally, an in-line high-speed molasses mixer can be installed after the main mixer. These are extremely effective if correctly positioned and used within the limitations of the subsequent conveying and storage systems.

Inclusion accuracy

While the density of molasses is reasonably stable at all times, the meals into which it is mixed vary considerably due to the variety of raw materials used in feed manufacture today. This is most apparent in mills where ruminant feeds are made. These feeds can contain materials as varied as Beet Pulp, Wheat-feed, Bran, Oat-feed and Sunflower husks. The precise addition of molasses must be given special attention where large variations in feed densities do occur. If these variations are not accounted for, there could be serious problems with molasses usage and pellet quality. Various methods using fully automatic controls linking a continuous weighing system are available to solve such difficulties.

Batch Mixing

The addition of molasses to specialised coarse type mixes for cattle, sheep and horses is completely different from the principle applied to meals. Most of the raw materials used are in pelleted, flaked, bruised or caked form and specialised mixing is necessary to preserve the state of the raw materials. This calls for mixers which have a gentle action. The addition of molasses to coarse mixes, aside from nutritional value, also makes feed more palatable, dust free and acceptable to stock. In coarse mixtures it is desirable for a major part of the molasses to remain on the ingredient surface after mixing, unlike meals where molasses has to be absorbed. To assist in the coating process, Premier Molasses makes a special molasses blend containing vegetable oils under the trade name of Molashine.