This article will benchmark different gravimetric weighing- and dosing solutions for dosing of nano- and micro ingredient where the target is to dose with very high precision, very high precision is defined as a few grams’ variety of easy and difficult flowing ingredients.

Over or under dosing of vitamins and other feed and food ingredients can cause serious health problems in for example animals that are fed with the product. It is essential for the producers of feed to be able to rely on the additives application system they use.

Design of a Nano and Micro Ingredients Dosing System needs careful assessment of the ingredients to be handled and dosed to find the best technical and cost-effective solution. A static scale will always be more accurate than a Loss-In-Weight or Continuous Scale and be easier to maintain and calibrate. Jesma produces weighing solutions using dosing screws and dosing slide gates of different sizes in addition to complete weigh control system for micro dosing systems (ATEX approved) and are therefore able to recommend the Best Practices solution for any application.

Jesma offers solutions for nano- and micro dosing including Loss-In-Weight (LIW ), Gain-In-Weight (GIW), and continuous weighing (CW) with very high accuracy and repetition.

Below we offer an overview of four weighing solutions with dosing screws, use of bins without agitators is also possible if the ingredients are easy and/or fair flowing.
For the GIW weighers type B, C, and D weighing takes place in a static scale after the Gain-in-weight principle, the number of load cells of the scales depending on the size/type of the scale. The Gain-In-Weight weighers is for batch operation only.

For the LIW weigher type A weighing takes places after the Loss-In-Weight principle, and the storage/ weighing bin is suspended in three load cells. This type can be used for batch- or continuous weighing operation.

Dosing screws, agitators, or another option?

Depending on among others the product and the capacity, dosing slide gates or dosing screws as wells as bin agitator or lifting screw and bin scraper can be offered.

Dosing slide gates versus dosing screws:

Dosing Slide Gates Dosing Screws
Medium and high capacity Low and medium capacity
Disadvantages:

  • Built-up caused by sticky products.
  • Higher in maintenance
  • Not suitable for sticky products
  • Higher risk for de-mixing/ segregation

Advantages:

  • Less energy consumption
  • Larger inlet area in relation to bin size – higher capacity
  • Gentle dosing of fragile products
Disadvantages:

  • Higher energy consumption
  • Reduced inlet limit capacity range

Advantages:

  • Superior dosing accuracy possible by adding pneumatic dosing cap at screw outlet.
  • Operation reliability
  • Handles also lumpy and sticky products as screw has a device which breaks up lumps.
  • More flexible bin/silo configurations possible

Bin Agitators versus lifting screw and bin scrapers:

Bin agitator Lifting screw and bin scraber
Disadvantages:

  • Higher risk for bridging /silo and bin hang-ups
  • Higher risk for ratholing
  • Compaction risk in some products
  • Higher risk for de-mixing/ segregation

Advantages:

  • Less expensive
Disadvantages:

  • High costs
  • Fragile products: Higher risk for product damage

Advantages:

  • Improved dosing accuracy possible
  • Better bin cleanout possible
  • Operation reliability
  • Handles also lumpy and sticky products.
  • Improved mass flow in bin

To summarize, high precision and repetition is important for the quality of the product, and it is essential for the producer to be able to trust the additives system precision. There are different types of solutions for weighing of micro and nano ingredients: Loss-In-Weight (LIW), Gain-In-Weight (GIW), and continuous weighing (CW) and Jesma can assist in choosing the most optimal solution for the customers product specification and capacities.

Explaining the Weighing principle:

Gain-In-Weight: The scale is suspended in load cells and during feeding product into the weigh bin it will gain in weight

Loss-In-Weight: The scale is suspended in load cells and during discharge of product from the weigh bin it will reduce its weight