Discontinuous addition of small volumes of liquids in an intensive mixer to animal supplement feed with different particle size distributions

Animal compound and supplement feed can generally be characterised as dispersible multi-ingredient mixtures in which particles differ in size, density and shape and tend to segregate. The segregation of animal compound and supplement feed is frequently a reason for customer and official complaints. To avoid segregation, usually small volumes of liquids – e.g. molasses or vegetable oils – are added in the main mixer of a feed production line to cause fractional agglomeration of fine particles. The presence of small volumes of liquids will affect the distribution behaviour of particles during mixing and it may also influence the material and technological properties. However, the mixing homogeneity of typical compound feeds that can be achieved when small volumes of liquids are present is not adequately characterised at the moment. There is insufficient knowledge of the process design and specifically the time of the liquid application in the mixing sequence.This study aimed to investigate the effect of adding liquids in customary amounts to animal supplement feed on the achievable mixing homogeneity as well as its dependency on the time of the liquid application in the mixing sequence. Major material properties, namely flowability and dusting potential, were determined to evaluate both the results and the product quality. An intensive mixer equipped with a feed pipe for liquid application was used as test facility. The results show that, under certain conditions, the addition of liquids in an intensive mixer may have a positive effect on the achievable mixing homogeneity of mineral feeding stuffs.

Graphical abstractThe addition of liquids while mixing feed powders may cause a fractional agglomeration on the one hand and may influence the achievable mixture homogeneity and the required mixing time on the other hand. The study aimed to investigate material and process parameters influencing the achievable mixture homogeneity when liquids are added discontinuously in an intensive mixer.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► The point in time of liquid addition showed no impact on the mixture homogeneity. ► A fractional agglomeration prevents segregation while mixing. ► Fractional agglomeration depends in particular on the particle size distribution. ► The results suggest that material-specific liquid optima exist.