Ease of use

The ease of use of a vitamin product is determined by its ability to be removed from the bag, transferred and measured efficiently in premix and feed plants. It is evaluated from the physical characteristics of the products. Understanding these properties facilitates the use of vitamin products in premix or feed plants and makes it possible to design more efficient equipment.

In practice, ease of use improves the efficiency in premix or feed plants by:

• Reducing dustiness.
  
  
• Improving flowability in storage and transfer systems.
  
  
• Eliminating residues in transfer systems.

The ease of use contributes to reducing the risks of cross-contamination in premix or feed plants as well as protecting the workforce and the equipment (risk of dust explosion).

Dustiness
Dustiness is the tendency of fine particles to separate from the main bulk of powder and then be dispersed into the atmosphere during product movement.

Dustiness affect:

• The safety of the workforce and of plants (explosion risk).
  
  
• The working conditions and the health of workers (allergy, respiratory disorders).
  
  
• The control of the product (wastage, cross contaminations).

Dustiness is measured by the" dust test". The electrostatic behaviors of the powders can also be the origin of unwanted phenomema : installations becoming electrically charged, and in some cases, explosions. Measurements of conductivity, chargeability, and aptitude to accumulate electric charges make it possible to closely predict the potential to have electrostatic problems..


Flowability
The flowability of a vitamin product is its capacity to flow freely in the tranfer system, from loading in the bin to the mixer.

Poor flowability results in bridging, caking, product loss in the transfer system; it also leads to transfer times which are incompatible with the running of the plant. Conversely, too fluid a powder may cause flushing.

Parameters for assessing flowability

• Angle of repose.

The angle of repose is the angle from the peak to the base of a cone obtained when formed on a perfectly flat and horizontal surface.

The angle of repose gives an overall idea of the flowability. Its measurement is described in the method ISO/R 902.

Adisseo has developed an elegant technique which uses a special funnel and circular surface for generating a refined cone as well as a scale of interpretation of the resulting angles of repose for vitamins.

• Apparent density/tapped density.

The apparent density (ad) or non tapped density is determined by the weight of product freely filling a standard volume.

The tapped density (td) is determined by the weight of product filling this same standard volume after removal of the air between the particles by tapping.

The methods for measuring the apparent and tapped densities are described in ISO methods 3953 and 697.

• Compressibility.

The compressibility is calculated by the formula:

For most powders, the compressibility makes it possible to evaluate the behavior of a powder in a static state (i.e., in a silo). If the compressibility is low " 20%). the product flows freely. If the compressibility is high (> 40%). the product packs and has a tendency to bridge in silos.

• Cohesiveness.

The cohesiveness is calculated by the formula:

The cohesiveness allows us to evaluate the behavior of powder in a dynamic state (i.e., the product's ability to be aerated and de-aerated). Low cohesiveness (< 1.25%) reflects the ability of the product to flow easily in transfer systems.

High cohesiveness (> 1.4%) leads to blockage of the powder in transfer systems or to clogging. In certain cases, too Iowa value leads to flushing.