Blending device for particulate material, with helical conveyer

In a device for continuously blending particulate materials including a central shaft having an axis, a plurality of metering means, each to meter a respective quantity of a respective particulate material;

• blending means to receive and blend the metered quantities of particulate material delivered from the respective metering means, said blending means comprising conveying means in the form of an elongate member having a rotating axis coinciding with said axis of said shaft, said elongate member being disposed helically in turns about and concentric to the rotating axis, means to rotate the elongate member about its rotating axis to trace out an envelope shape of the casing in which the conveying means is located, said casing having a discharge end and a lower portion conforming to said envelope shape of the helically formed elongate member, the conveying means rotating in the casing so as to generate a conveying direction for particulate material in the casing towards the discharge end thereof, and stirring members provided on the conveying means and extending between at least some adjacent turns of the helically formed member, the elongate member having a cross-section which is of arcuate form at least on a side thereof facing said conveying direction to create an inefficient conveying means, and the stirring members being arranged on an outside portion of at least some adjacent turns of the elongate member, the stirring members extending a full length of the helically formed member so that the adjacent stirring members are positioned alternatingly inside and outside the helical turns, each metering means including a respective metering conveying means formed from a metering elongate member having turns helically disposed about an axis of rotation, means to rotate the metering elongate member about the axis of rotation, a metering casing to contain the metering elongate member, the metering casing having a lower portion, the turns of the helically formed metering elongate member rotating so as to trace out an envelope shape, said lower portion of the metering casing conforming to the envelope shape of the helically formed metering elongate member, at least some of the metering conveying means in the metering means are equipped with means to vary a pitch of a helix of the respective elongate member;
• a single prime mover, the conveying means in the metering means and the blending means being driven from said single prime mover at correlated speeds of rotation.