The core equipment for the production of ready-mixed powder is the mixer, commonly used vertical ribbon mixer, paddle mixer, horizontal ribbon mixer, plough mixer and other forms. At present, large-opening paddle mixers and plough mixers are mostly used for ready-mixed powder.

1. Vertical ribbon mixer
The vertical ribbon mixer is mainly composed of a mixing barrel, a vertical ribbon, and a flying knife group. The middle spiral rotates circumferentially, and the flying knives on the side of the barrel rotate at high speed to chop the coagulated material. This series of mixers is suitable for mixing fine materials or granular materials, and mixing highly uniformly distributed fine powders, greases and other liquid and semi-liquid materials. The large, quick-opening door on the side of the mixer makes cylinder cleaning convenient and efficient. The vertical ribbon mixer discharges cleanly and leaves little residue, making it suitable for use in food processing. However, in the current ready-mixed powder industry, horizontal mixers are generally used.

2. Paddle mixer
The paddle mixer consists of a horizontal cylinder, a transmission mechanism, a mixing blade, and an optional crushing rod. When working, a good mixing effect can be achieved under the rapid and violent tumbling and throwing of the staggered mixing blades. The discharge port is divided into large door type and small door type. The large door type discharges materials quickly and leaves less residue. The advantages of this equipment are wide range of application, high mixing uniformity, short mixing time, but there is a certain amount of residue, which is easy to cause secondary pollution. Currently, it is widely used in the ready-mixed powder industry.

3. Plough mixer
Plough mixer consists of a circular cylinder, transmission mechanism, plough, fly cutter, structure schematic diagram in Figure 1. plough knife mixer with the main shaft rotating at the appropriate speed, the material in the cylinder by the plough knife strong action and thrown up, part of the wall along the cylinder to do the circumferential movement, the other part of the material is thrown to the centre of the cylinder or along the plough cutter tangential direction to the ends of the fly scattered. When the material flows through the high-speed rotating fly cutter, it is sheared at high speed or strongly diffused, and the common action of the plough head and fly cutter blade makes the powder produce a centrifugal throwing convection movement, and mix with each other fully in a short time. The trajectory of the material in this equipment is longitudinal and transverse, especially for the material that is easy to agglomerate, it can play the role of deagglomeration and breaking up.

Figure 1 Structural diagram of plough mixer

4. Horizontal ribbon mixer
The horizontal ribbon mixer consists of a U-shaped cylinder, ribbon mixing blades and transmission components. The structure is shown in Figure 2. The spiral ribbon-shaped blades are generally double-layered. When working, the outer spiral ribbon collects materials from both sides to the middle, and the inner spiral ribbon transports materials from the middle to both sides, forming convective mixing. The advantages of this equipment are wide application range, high mixing uniformity, short mixing time and large loading coefficient.

Figure 2 Structural diagram of horizontal ribbon mixer

5. Application of different types of mixers
Taking a 6 m³ mixer as an example, the power consumption, external dimensions and weight of different types of mixers are compared. It can be seen from Table 1 that different types of horizontal mixers of the same volume have similar loading coefficients. The plough mixer consumes the most energy, while the ribbon and paddle mixers have relatively smaller energy consumption. Horizontal mixers occupy a large area and are low in height, suitable for projects that are subject to height restrictions and require construction first and layout planning later; vertical mixers, which occupy a small area, have a large loading factor, have low energy consumption, and have no residue, are suitable for projects that are not subject to height restrictions. 

Table 1 Comparison of different types of mixers