Apparatus and method for de-dusting bulk materials

Abstract

In batchwise operation, the granules (4) are fed into the de-dusting tank (9), which has no closure element at the lower granule-outlet opening (25) and for which the swirling nozzles (31), for the introduction of compressed air, are arranged in a lower cone structure (28), and - in particular depending on the filling level in the intermediate tank (14) located beneath - either can fall downwards without any counterflow (32), wherein de-dusting takes place as a result of the air introduced being pushed out, optionally on account of the negative pressure which is present at the upper air-outlet opening, as a result of which only free-floating particles of dust are extracted, or a counterflow (32) is introduced at the stage of the feed-in operation and said counterflow, rather than allowing some of the fed-in particles (4) to fall through the granule-outlet opening (25), retains said particles in something of a floating state at the level of the lower third, or lower quarter, of the de-dusting tank (9). As a result of the counterflow (32) being controlled, it is possible to control the height position of the region of reversal (30) of the highly swirled-up granules (4) and also the residence time of the granules (4) in the de-dusting tank (9), and thus also to operate the apparatus continuously.

Description

technical field [0001] The invention relates to the removal of dust from bulk materials, in particular by means of ionization, wherein the dust usually adheres to the grains of the granulate, especially by means of electrostatic charging. Background technique [0002] In pharmaceutical and food technology, especially in plastics technology, it is often necessary to work with raw materials in the form of bulk materials (eg granules, pregrinds, coarse powders, etc.). For the purposes of this application, all bulk materials are denoted by the simplified term "pellets". [0003] The conveying of these loose materials is often carried out by means of pneumatic conveying, especially by dilute phase conveying, during which the pellets are transported by means of an air flow and mostly suspended together in the air flow through the conveying line to the desired Location. [0004] For further processing, eg as raw material for injection molding machines, the pellets should be as cl...

AI Technical Summary

Problems solved by technology

However, this may result in more fines due to collisions of the pellet grains, resulting in further dust generation

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