Mixers and mixing

In general, agitators can be classified into the following two groups. 

1 Agitators with a small blade area which rotate at high speeds. These include turbines and marine type propellers. 

2 Agitators with a large blade area which rotate at low speeds. These include anchors, paddles and helical screws. 

The second group is more effective than the first in the mixing of high viscosity liquids. 

The mean shear rate produced by an agitator in a mixing tank ym is proportional to the rotational speed of the agitator N [Metzner and Otto (1957)]. 

---

Figure 8.32 Kenics mixer and mixing quality as a function of the helix angle [58] (courtesy of Han Meijer of Technische Universiteit Eindhoven)...

Mixer and mixing vessel subclasses primarily are distinguished by the mixing energy, mixer type, and whether a jacketed vessel with vacuum capabilities is used in conjunction with a specific mixer. 

One of the most frequently applied tests is in the study of additive incorporation and compounding. All of the additives used in a formulation must be incorporated in the major component, and the components should be in a stable molecular arrangement. Figure 12 illustrates a test result for incorporation of minor components to the major component as well as homogeneous compound after the additives are incorporated. The test was performed with an EPDM rubber and reblended additives. The EPDM was loaded into the mixer and mixed... 

A type of processing equipment in which the entire amount of material to be used is put into the mixer and mixed for a definite period, with multiple recirculation of material through the mixing zone, in contrast to what happens in a continuous mixer. After the mixing period the whole amount of material is removed from the mixer. In oil production or processing, the process in which emulsion is collected in a tank and then broken in a batch. This process is used as opposed to continuous or flow-line treating of emulsions. 

Blending can, in a first instance, be carried out in dry condition in the polymer powder or granules the degree of blending is, however, not yet sufficient. To obtain a better dispersion, a blending process in the fluid state is necessary. To achieve this, various types of mixing devices are available, such as roll mills, internal mixers and mixing extruders. 

Except for the CMUs which were produced in an industrial block plant, the batches were completed following the same procedure. Before starting a typical concrete batch, the water, sand and pea gravel were adjusted for moisture content. The two aggregates and the plastic filler were introduced into the mixer and mixed for approximately 30 seconds. The cement and two-thirds of the total water were added and the drum was rotated for 2 minutes more. The rest of the water was added within the next 30 seconds. After two minutes the drum was stopped, and the slump test was performed. The drum was then scraped to loosen any material not previously mixed. It was restarted and rotated... 

Norway by Forberg AS. Although the shape of the mixer and mixing elements differ from the. Littleford design the general idea is very... 

Rinse the container with 10.0 g item 10. Add to the mixer and mix for 10 minutes. Transfer the dispersion to the mixer. 

Transfer the ointment in a mixer and mix for 5 minutes with electric mixture. Fill the ointment. 

Uniform sand mixes can be prepared by adding the binder to the sand in conventional foundry mixer, muller, or mix-mixers, or laboratory or kitchen mixers, and mixing for sufficient time to obtain a good admixture of the sand and binder, e.g., for several minutes. When added separately, it is desirable to mix each component for less than 2 min to avoid undue drying. 

Two more 101b sand mix batches were made by adding 23 g of Nusheen kaolin powder furnished by the Freeport Kaolin Co., 0.5 lbs of the binder solution and 0.7 g of phenolphthalein to 10 lbs of the same Houston sand AFS 45—50, while stirring in a 10 lb Clearfield mixer, and mixing for 2 min. The kaolin powder and the binder mixed readily with the sand and a uniform sand mix with excellent flowability containing 5% of binder and 0.5% of kaolin by weight of sand was obtained in this manner. The sand mix was kept in a closed polyethylene bag for about 4 h before using. 

First, fibres and 4BS nucleants are introduced into the paste mixer and mixed for 1 min, then the leady oxide is added. The dry mix is homogenized for 3 min and then water heated to 80 °C... 

The most commonly used technique to qualify filler dispersibility is to study light reflectivity of clean-cut mixes. Some apparatuses have been developed to evaluate filler dispersion using a calibrated set of reference mixes (Dispergrader). However, such characterization mainly detects dispersion defects of a few tens of microns, and direct comparison of carbon black and silica mixes has to be done cautiously. In any case, it is necessary to make a mix, which means choosing a formula, a mixer, and mixing conditions thus the result cannot be considered as an intrinsic dispersibility measurement of the filler, but just reflects the dispersibility of the filler in one mix with a set of mixing conditions. 

Mixing devices are generally divided into two main categories static mixers and mixing elements (also known as dynamic mixers). The use of mixing elements on the screw is far more popular than the use of static mixers. 

All components in the pellet form (polymer pellets and other additive pellets) are pre-weighed in the desired ratio and added to the ribbon blender or other similar mixer and mixed until dispersed uniformly. From here, the blend is conveyed to the feeder as needed. 

Otsuka M, Gao J, Matsuda Y. Effects of mixer and mixing time on the pharmaceutical properties of theophylline tablets containing various kinds of lactose as diluents. Drug Dev Ind Pharm 1993 19(3) 333-348. 

---