Watch an experts’ discussion on liquids additives use at mixer and at post-pelleting stages. The webinar “Liquid additives: an opportunity of value!” enabled exchanges on liquids additives use at mixer and at post-pelleting stages.The Answers to the questions sent during the live are available now on the Forum

Franck Ducatel, Operation Director at Cargill Premix France and president of Tecaliman, Joan Brussosa, International Sales/Project Manager at Mangra and Marc Perel (Solution Application Manager) were on the set to host the live webinar. Anna Perez, Reaseach Director Analysis, IRTA was also interviewed to give an analytical point of view.

Questions and Answers session

As mentioned during the live webinar, the “liquid additive equipment maintenance check list” can be downloaded via: http://bit.ly/39SbeQn and to know more click here.

   First, a dry mixing time is needed to homogeneize the solid ingredients. Before addition of micro-liquids, it can be quite short (a few seconds). Then comes the addition of liquids -time depend on quantity and flow). They can be applied simultaneously since the flows do not overlap. Lastly, the third mixing time allows to finalize the repartition of liquids within the batch. All automation systems have different approaches to consider these different times but things must be cleared between the feed manufacturer and the PLC company.

Compared to powder dosing, the injection of liquid requires specific equipment whose maintenance is more delicate. What are the practices to recommend for monitoring "weighings"? (pump, plastic or metallic material, injector ...)

Maintenance of liquid system is not a big deal. It consists mainly on checks and verifications. Please have a look to Adisseo's check-list proposal.

Is the premixing of liquids a recommended practice?

As far as possible, managing each liquid seperately is recommended (from storage to spraying). But if there is no adverse interaction, liquids can be put together before addition in the mixer.

How to ensure the good dispersion of the active liquid materials in the mixer?

Spraying is a matter of choice of nozzles (number, type, size, angle), location, pressure and viscosity in some cases.

From the point of view of the incorporation of liquids, are there differences in behavior between the different types of mixers?

The equipment supplier must consider the type of mixer (single/double shaft - ribbon/paddle...) to implement the nozzles. Spraying quality is of bigger importance than the mixer type. The filling ratio of the mixer is also of importance (distance between the sprays and the feed; are the shaft and ribbon or paddles covered by the feed?).

If we have powder micro ingredient and want to apply it with oil on feed, what would be the suggested mode of application, as oil suspension (powder directly in oil), as water dispersion (powder into small quantity of water and than water solution into oil) or as an emulsion?

It mainly depend on the physical and chemical properties of the additive (particle size, solubility, rate of inclusion, stability....). Today this topic is more research program. 

Is there any limit as for the amount of additives that recommend applying with a post-pellet dosing equipment? (enzymes and/or probiotics)?

Fortunately, additives are quite concentrated. Even if the manufacturer wants to spray 2 or 3 different products, an addition of 1 liter per ton or a bit more is doable.

What is your opinion about the feed mills having PPLA system without sieving the pellets before liquid application. Can this system be accurate enough?

Of course, this is not the best option. THe final result will then depend on the 3 factors: initial quantity of fines in the feed, pellet durability, stresses during feed storage, transportation and distribution to the animals.

Which is ithe most efficient Post pellet liquid applicator available now? For Fish feeds, With less cost, Any options...Pls explain the working if possible.

Many suppliers propose proper PPLA systems. For fish feed, adding liquids continuously in a drum coater is common. A more recent technique is vacuum batch coating to apply high levels of fats and oils. Liquid additives are applied at the same stage.

Thank you for the ongoing live about liquid additives in the feed mill. We often face the following question from our customers on liquid application system.Kindly requesting your insight on the same. Can we mix macro ingredients (oil) with Micro ingredients(Amino acids/Acitifier) while spraying into batch mixer? Or All Micro ingredients together ? Thank you for your clarification.

As far as possible, managing each liquid seperately is recommend (from storage to spraying). But if there is no adverse interaction, liquids can be put together before addition in the mixer.

How should the liquids and palatabilizer be added together or separately?

In general, palatants require less accuracy in term of dosage and spraying compared to other types of additives. They can be easily sprayed on a mechanical conveyor. This is why they are independent most of the time. Before mixing with another liquid, incompatibility of molecules must be assessed.

Is dry mixing necessary in the mixing time or we can skip it and start liquid spray after loading?

With flowmeters we can have dedicated lines and mixing them into the manifold is optional. We can use different manifolds for those liquids which could not be mixed. It is a closed and cleaner system.

How can we choose between hidraulic or atomizing nozzles.

Refering to Post-Pelleting Liquid Application, the optimum is to create micro-droplets, not a mist. Pure hydraulic nozzles will not produce micro drops, so air is necessary but no so much because we want to get a fine dosing (micro drops) but avoid nebulization (mist).

How do I define the maximum inclusion based on free water resulted from this liquid additive?

In formulation, water content of liquid additives must be considered the same way as for solid ingredients (a value in matrix). In practice, water content of additives is never limitating. With weighing scales it is necessary to add each liquid separately and sometimes mix them before addition into the mixer or use dedicated scales for each liquid. The scaled vessel always keeps traces of the previous mixture and is more difficult to flush and clean.

What are the benefits of flowmeters comparing to weighing scales?

With weighing scales it is necessary to add each liquid separately and sometimes mix them before addition into the mixer or use dedicated scales for each liquid. The scaled vessel always keeps traces of the previous mixture and is more difficult to flush and clean.

What are the advantages of mass flowmeter compared to volumetric flowmeter?

A mass flowmeter measures Mass Flow (kg/min), regardless the actual density value. If there are changes in density value, the flow meter corrects it automatically.
A volumetric flowmeter measure Volume Flow (l/min). As the dosing is made in mass, it is necessary to change from Liter to Kg in the electronics using the actual density value. If the density varies, the conversion to Mass could be slightly affected and alter dosing accuracy.

What is the best sequence for adding different liquids? Is it ok to spray all liquids in the mixer at the same time, if the mixing time is very short?

Please refer to the 1st question in the Forum.

After a mixer profile test, What should we recommend a customer when the CV of the liq is not as good as the powder? What are the advices to improve CV for liquid?

This is a very open question. Apparent heterogeneity can have different sources: actual quality of spraying (place, geometry, pressure, steadiness of the flow...). Let's not forget the analytical process i.e. sampling and lab analysis.