1、 Question raising

As is well known, every thing has two extremes, and the same applies to powder mixing. The equipment specification that is usually suitable for dry powder mixing is a bucket volume between 100 and 600 liters. The feeding, discharging, mixing time, powder pressure, and mixing uniformity of the mixer are all in good condition, and the mixing effect is good. If the volume of the equipment increases or even exceeds 1000 liters, uniform mixing becomes difficult and the mixing time will be greatly extended.

2、 The impact of oversized mixer specifications on mixing uniformity

Analyze the impact of oversized mixer specifications from two aspects:

1. Due to the excessive space in the mixing machine bucket, the span of powder movement increases, thereby increasing the difficulty of uniform mixing. This is because the range of powder activity is large, and the difficulty of diffusion and convection mixing increases. The space and time for powder components to flow from left to right and from bottom to top increase, and the distance of powder particle movement and displacement increases, resulting in an increase in mixing difficulty;

2. The total amount of powder involved in mixing increases, meaning that the powder particles always increase significantly. The displacement exchange between powder particles during the mixing process greatly increases the workload. These factors increase the task of powder mixing and prolong the process of uniform powder mixing. Under normal circumstances, selecting a mixer can optimize equipment with a bucket volume of 100-600 liters. If a large mixer must be selected due to one-time batch requirements, the mixing time should be extended in the mixing process to achieve uniform mixing.

It should be noted that in extreme cases, the mixer size is too large, and even if the mixing time is extended for many times, it is difficult to achieve uniform mixing.

3、 The Influence of Small Mixer Specifications on Mixing Uniformity

If the specification of the mixer is too small (such as less than 10 liters), it will appropriately weaken the mixing capacity of the equipment and reduce the mixing efficiency.

Analysis reason: Due to the small volume of the mixing equipment bucket and the small stacking height of the powder involved in mixing, the gravitational pressure between the powder particles in the bucket is relatively small, which means the powder pressure is relatively small. Therefore, the mixing method based on the principle of gravity diffusion is not ideal for mixing. Especially when using a small-scale mixer to mix light powder (powder with a specific gravity ≤ 0.35), the mixing effect will be even worse.

Therefore, if the size of the mixing machine barrel is too small, it will also reduce the mixing capacity of the mixing equipment, causing a certain impact on the uniformity of mixing.

Summary: 1. If the specific gravity of the powder to be mixed is large (greater than 0.8), using a small-scale mixer can basically mix normally and achieve the mixing purpose. This is because the specific gravity of the powder is relatively high, and the powder pressure between the powders is also relatively high, meeting the normal mixing requirements.

2. If the specific gravity of the powder to be mixed is small (less than 0.5), using a small-scale mixer (with a volume less than 10 liters) will affect the normal mixing process and make it difficult to achieve uniform mixing.

3. Powders with a specific gravity between 0.5 and 0.8 should be treated as appropriate.