Mixing & Dispersion Systems and Choosing the Right Mixer

During product preparation, the mixing process is quite important when considering proper adjustment of raw material doses and production technology. The operation of distributing powders or liquids thoroughly and completely within each other is called "mixing."

The prepared homogeneous system is called a mixture. The purpose of the mixing operation is:

1. Mixing two or more liquids or powder substances that can be mixed with each other, 2. Mixing solid particles that are insoluble in a liquid (such as suspension), 3. Distribution of particles in a carrier such as emulsion, suspension, liquid, or ointment. In mixture preparation, liquids, gases and vapors that do not require external energy for mixing and mix easily with each other combine instantly through diffusion; this phenomenon is called positive mixing. The process of mixing solid particles in a liquid that are insoluble in the liquid and settle to the bottom of the liquid when the mixing operation stops is defined as negative mixing. We can clearly distinguish between dispersion and mixture using ambient velocity logic. Consider a line ranging from 1-25 m/s. The operation occurring between 1-19 m/s on this line is called mixing, and the operation occurring between 19-25 m/s is called dispersion. Dispersion also means distribution. To capture dispersion in mixer machines or, in other words, dissolvers, it is necessary to select appropriate motors, impellers (mixing disks) and transmission elements. Mixing low-viscosity liquids is easier. However, the mixing operation required for adding powder substances to these liquids, that is, creating suspensions, is more difficult. This is because the powder particles begin to settle downward the moment mixing stops. When a viscous liquid is used, settling is slower, but the mixing operation becomes more difficult. "High-Speed Mixers" designed for the production of low-viscosity products are devices designed to work at high speeds to disperse maximum product in the minimum possible time. These types of devices are used especially in applications where homogeneity of liquid with powder or liquid with liquid and dispersion are required. These mixers with effective motor power suitable for the density of products with various viscosities can serve in the production of paints, inks, varnishes, pigment paste, and various petrochemical products. These types of mixers can have fixed single speed or, with speed control, variable speed. Since the speed control inverters used in Sözer Makina mixers are heavy-duty type, they have the capability to provide power above the mixer's motor power for short periods if needed. These types of mixers generally operate in the range of 100-1,500 rpm. In the mixing of some low-viscosity products, although fluidity is high, sometimes fast-speed dispersion alone is not sufficient, and heavy-speed blending is also required. "Combination Mixer Machines" preferred in the production of such products have a wide range of applications due to their high and heavy-speed mixing capabilities operating simultaneously or at different time intervals. These systems reduce the operation of two different machines into one. These types of machines have two or three mixing systems on them. The first consists of two dispersion impellers on a shaft operating in the 100-1,500 rpm range; the second has two butterfly mixers on a shaft operating in the 50-400 rpm range and a center scraper-mixer system rotating at fixed 20 rpm. In two-shaft combination mixers, the butterfly mixer and scraper system are located on the same shaft. When we move on to mixing medium-viscosity products, "Planet Malaxer Machines" come into play. Planet malaxers are generally used in the production of construction chemicals with medium-density viscosity (all types of putty, paste, sealant and waterproofing components, adhesives, plastisol, etc.) as well as in the pharmaceutical and food sectors. These machines with a planet mixing system have two mixing systems. The first is a dispersion impeller operating on a central shaft operating in the 100-1,500 rpm range, and the second is two planet mixing systems located on the sides operating in the 0-100 rpm range. In addition to rotating around their own axis, these mixing blades orbit within the bowl due to the rotation of the block to which they are attached above, increasing mixing efficiency. With the help of blades positioned at various angles on these shafts, effective and homogeneous mixing is achieved in a very short time through the upward and downward movement of the product within the bowl. Additionally, since the mixing shafts rotate in opposite directions to each other, homogeneous mixing is provided without heating the product. Besides the mixing shafts, the scraper arm also provides great advantage in drawing the product from areas close to the bowl wall. The scraper arm, with chemical-resistant polyethylene material at the edge and on the lowest mixing blades, provides scraping of the side wall and bowl bottom. Finally, "Z-Mixer Machines" are preferred in the production of very high-viscosity products. Z-mixer machines are widely used in mixing from low viscosity to very high viscosity range, from various adhesives to rubber-based products. Examples of application areas include Hotmelt adhesive, rubber, BMC and SMC dough, fiberglass-reinforced products, and brake lining production industries. With two specially designed "Z" mixing paddles with a horizontal mixing system rotated at different speeds within the bowl, extremely homogeneous kneading and mixing is achieved. Due to the special shape of the mixing paddles, compared to conventional "Z" type mixers, it provides much shorter time and effective mixing. The complete stainless steel internal walls of the mixing bowl and the steel-cast mixing paddles, as well as the use of European-origin sealing elements in the bearings, are offered as standard features on the machine. "Z" type mixing paddles are designed to operate in both directions. Two types of product discharge systems are offered for the Z-mixer machine. With the mixing bowl remaining fixed, an endless screw operating at the lowest point of the bowl enables the product to be discharged outside the bowl. This screw operates in both directions and also benefits the mixture during production. The other product discharge system is the bowl rotation system. The bowl rotates at a 110-degree angle, allowing the product inside to pour out and be removed from the bowl. T. Emrah Sözer Industrial Engineer Production Director Sözer Makina