Agglomerator / humidifier for crop protection agent production

To ensure good flow properties, a longer shelf life, good dispersibility and wettability (when reconstituted into the liquid phase prior to spreading in the field), pesticides are nowadays mostly produced either as dry agglomerates or as dry, extruded product, having the appearance of either small cylindrical shaped or, after an additional treatment in a Spheronizer, spherical particles.

Agglomerates

Agglomerates are produced by thoroughly mixing the micronised, powdery premix with a liquid binder, such that the particles will stick to each other to form larger particles. The eventual grain size (0.3 - 1.4 mm) of the agglomerates depends among others on the ratio of the binder to the powder.

In case of the extruded product, a low-pressure extruder is used, in which an extrudable mass will be pressed through a screen (orifice plate) with perforations of 1 - 2 mm. The low pressure in which this extrusion takes place ensures that the extrudates remain relatively porous and therefore maintaining the required good dispersibility. A humidified feed product with very homogeneous moisture content is essential to achieve optimum extrusion results with a maximum yield and minimum of clogging of the extruder.

Suitable equipment

For both agglomeration and extrusion process, Hosokawa’s Flexomix is the most suitable equipment. The Flexomix, a high speed, continuous instant mixing equipment, ensures very even, homogeneous humidification of the particles.

Agglomerated product

In case of agglomeration, the homogeneous mixing in the Flexomix ensures efficient formation of agglomerates with uniform quality, resulting in a high process yield. These agglomerates are porous and slightly irregularly shaped ensuring a good wettability and dispersibility. The Flexomix has a self cleaning mixing chamber, which minimises adherence of moist product to the mixing chamber wall, allowing a relatively high liquid addition ratio as required. The agglomerates formed in the Flexomix fall from the Flexomix into a fluidised bed dryer and are dried to the required final moisture content.

Extruded product

In case of extrusion, the feed product is evenly humidified in a Flexomix prior to the extrusion step. A possible technology for extrusion can be the Bextruder, made by Hosokawa Alpine Compaction.

Agglomeration process

In new plants, the Flexomix is the equipment of choice for both a direct agglomeration process as well as the wetting / humidification step in case of an extrusion process to ensure a maximum extrusion performance. In a lot of cases, the installation of the Flexomix in existing plants to replace existing  (less effective) agglomeration or humidification devices has also proven to be very successful to significantly increase the yield and reduce the down time due to e.g. clogging to a minimum. The Flexomix is used by major water dispersible granular crop protection agent producers world wide.