Ribbon mixers

Ribbon Mixers

Ribbon mixers are discontinuous mixers, consisting of a trough vessel and a rotating shaft with circular helical mixing knives. These knives are called ribbons. There is an outer large ribbon helix and an inner small ribbon helix. These two helical ribbons have countercurrent rotation, thus enabling a perfect mix.

Batch ribbon mixers of a specific capacity mix each time the specific batch, e.g. 1000 kg in the specific mixing time, e.g. 3 min.

Dead times of mixer filling and mixer emptying should be counted in a full batch cycle.

There is usually a (horizontal) rotating shaft with either 2 rows of counter-current stirring knives called ribbons, or paddles, depending on the requirements of the mixture.

At the bottom of the mixer, there is an emptying valve, usually driven by a pneumatic actuator or cylinder. Important issues of batch mixers are a reliable and dust-tight outlet valve, a quick emptying time of the mixer, and full emptying of the mixed product.

The mixing time and the degree of homogeneity of the mixture are related to the cost and quality of each mixer.

To increase the efficiency of a mixing plant, it is useful to foresee a weighing hopper over the mixer and a buffer of similar capacity under the mixer.