Browse our products by application OR simply search for a product by name:

SIPERNAT® D17 in Agricultural Formulations and Animal Feed

eye 5 Minute Read eye By Martin Scott
A white granular substance being poured easily while flowing well

 

A high-performance free-flow additive for hygroscopic powders

The flow characteristics of a formulation are something that are often taken for granted. Although often associated with liquids, powders need to flow as well and, depending on the application, can be anything from annoying to costly when they don’t flow easily. Due to the large contact areas and hygroscopic nature of powders, they are prone to clumping and caking, particularly if they take on moisture. This clumping can cause handling issues that can block up machines or make quantity measuring less precise.

Within agricultural formulations, NPK or chlorine-based feed premixes exhibit these problems. SIPERNAT® is a range of speciality precipitated silicas produced by EVONIK that address caking and free flow in technical powder formulations and can improve properties for long periods of time or in humid environments.

 

In this technical article:

 

What is SIPERNAT® Precipitated Silica?

SIPERNAT® precipitated silicas are derived from water glass to which sulphuric acid is added under controlled conditions. This causes the silica to develop in the water phase. Depending on the conditions the silica is produced under, it is possible to define the primary particle size of the material. The precipitate formed can then be washed out and dried to create the powder you see as a final SIPERNAT® product. Depending on the drying process employed it is possible to also control the morphology of the silica. For example, conventional roll driers may be used alongside grinding to obtain a more plate-like morphology or alternatively spray drying can give a more uniform and spherical product. A much freer flowing powder is possible to obtain from the spray drying method.

Some SIPERNAT® precipitated silicas, such as SIPERNAT® D17 are after-treated in a further production step to convert the naturally hydrophilic surface of the silica into a hydrophobic one. It is this after treatment of SIPERNAT® D17 which gives it some advantages over its SIPERNAT® family members in certain conditions.

 

A liquid and powder are poured respectively on the left and right. Both are flowing easily.

Figure 1: Vitamin E-acetate as liquid and as adsorbate on SIPERNAT® 2200 showing its ability to act as a liquid carrier.

 

How Does SIPERNAT® Precipitated Silica Help in Technical Powders?

For the purposes of this article, we can split the SIPERNAT® precipitated silicas into two groups; These are carrier materials and free flow additives.

Carrier materials allow liquids to be dispersed onto their surface to form free-flowing powders. Their hydrophobic and highly absorbent nature allows this behaviour. As a general rule, carrier materials are larger with average sizes of 50-400 microns and include grades such as SIPERNAT® 50SIPERNAT® 22 and SIPERNAT® 2200.

The free-flow agents such as the hydrophilic SIPERNAT® 22s, SIPERNAT® 50s and the hydrophobic SIPERNAT® D17 are smaller in size ranging from 10-16 microns. This size allows them to distribute well across the powder or granule surfaces as shown in figure 2.

A before and after of a host powder with the addition of SIPERNAT. The SIPERNAT has coated the host powder preventing further moisture uptake and seperating the two granules.

Figure 2: The addition of precipitated silica can help separate the granules or powder particles by absorbing or repelling the moisture that is creating the liquid film and caking. 

 

In particularly hygroscopic formulations, moisture can surround the powder or granules to the point where caking occurs and free flow can become impossible. In these formulations, adding a hydrophilic SIPERNAT® that will disperse onto the surface of the powder or granule could be the solution. The precipitated silica can then absorb the moisture to create an environment where free flow is possible. However, the precipitated silica’s ability to absorb moisture is finite so in cases where this isn’t enough, SIPERNAT® D17 can be used.

 

Why use SIPERNAT® D17 over other SIPERNAT® grades?

SIPERNAT® D17 differs from hydrophilic silicas due to its chemically modified hydrophobic nature. Therefore its mechanism of action is different to its SIPERNAT® product family members. SIPERNAT® D17 will still disperse onto powders and granules but instead of absorbing, it will help to repel moisture away from the formulation completely.

Where is this action of moisture repellence useful?

  • Particularly hygroscopic powders which are prone to caking.
  • Powders which may be used in humid areas.
  • Formulations in bags or containers which may not be resealable and used over a period of time
  • A combination of all of the above!

 

Two test tubes with blue powder in, one is flowing out the small hole at the bottom easily and the other is caked and stuck.

Figure 3: Having powder cake together can cause a few different issues, including reduced free flow ability. Here, the same powder but with and without precipitated silica (right and left respectively) shows the difference in this characteristic. 

 

What are the benefits of SIPERNAT® D17 in Agriculture and Animal Feeds?

Within agriculture and animal feeds, there are many powders and granules that need to go through machines and be poured into bags. This, of course, means that their flow characteristics are important. A mix that cakes can be difficult to handle as it could clog up machines and stick to the components. Adding small quantities of SIPERNAT® D17 can improve the free flowability by the methods described previously. 

With the modernisation of agriculture and farming, automated processes that demand precise dosing and a consistent composition are becoming more prevalent. SIPERNAT® D17 can give the free-flowing nature required for these as well as giving a consistent quality throughout batches and reducing the time each product needs to spend on plant which could also lead to an overall cost saving.

 

Pellets of animal feed that flow better with the addition of precipitated silica.

Figure 4: Improving the flowability of animal feed mixed with SIPERNAT® D17 can reduce time and costs associated with handling the feed.

 

Summary

The SIPERNAT® range from Evonik offers a range of advantages depending on the grade; They can be hydrophilic and absorb the moisture to keep it from the host powder or hydrophobic and repel the moisture for the same purpose. They can have different sizes to give multiple options for distribution within the powder. They can be liquid carriers to give the improved handleability of powders or free-flow aids to reduce caking within a product that is already a powder.

SIPERNAT® D17 is recommended for use within agricultural and feed premises as it can offer time and cost savings by giving better flow characteristics and therefore improved handleability and dosage precision. For more information or to find out how it could work for your formulations get in contact with us to speak to our technical sales manager for the agro-industry.

 

Headshot of Technical Sales Manager, Martin Scott
Martin Scott, Technical Sales Manager

Coatings and Agrochemicals

Martin completed his Chemistry degree with a focus on Medicinal Chemistry at the University of Warwick in 1999. Since then he has held several Sales and Management positions in the chemical industry. He has now been with us since 2014 and looks after accounts in the Coatings and Agrochemical industries.

arrow View All Articles By Martin Scott
Share this article
You might also be interested in...