# Critical velocity of solid mineral fertilizers in a vertical upward airstream and repose angle

Laen...

## Kuupäev

2017

## Kättesaadav alates

## Autorid

Hůla, J.

Kroulík, M.

Honzík, I.

## Ajakirja pealkiri

## Ajakirja ISSN

## Köite pealkiri

## Kirjastaja

## Abstrakt

Critical velocity of mineral fertilizers in airstream is important not only at the
application of fertilizers by spreaders but also at combine of fertilizing and sowing. The
knowledge of angles of repose is important to design hoppers on spreaders for solid mineral
fertilizers. Critical velocities for six solid mineral fertilizers were measured in the vertical
aspiration duct of a laboratory sorting machine. Variation curves were constructed for particular
fertilizers and the mean critical velocity of fertilizers (velocity of uplift) was computed. The mean
critical velocity of fertilizers was between 8.53 and 12.43 m s
-1
. The lowest critical velocity was
found out in the fertilizer UREA 46%, the highest in the fertilizer LAV. Statistical significance
of differences in the critical velocity of fertilizers was assessed. Angles of repose of eight solid
mineral fertilizers were also measured and statistical significance of differences was evaluated.
The highest values of repose angle were determined for potassium salt and ammonium sulfate
(35.9° respectively 34.9°), the lowest values for UREA and LAV (28.7° respectively 29.6°). The
obtained results extend information applicable to an assessment of parameters of the operation
quality of spreaders during mineral fertilizer application.

## Kirjeldus

Article

## Märksõnad

mineral fertilizers, variation curves, repose angle, articles