Process flow of the compound feed processing unit

I. Batch Processing System for Compound Feed Processing Units
Formulation is the core of feed‑processing technology, and the accurate implementation of a feed formula depends on precise formulation techniques. Changes to the batching system are primarily aimed at accommodating an increasing variety of ingredients, reducing inclusion levels, enhancing weighing accuracy, shortening the weighing cycle, and boosting throughput per unit time. An instrument currently being tested for installation on existing equipment enables on‑line chemical analysis of raw materials, allowing the determination of various constituents such as amino acids, moisture, crude fiber, and starch. Consequently, it will be possible to dynamically reconfigure feed formulas and produce feeds with exact specifications, thereby stabilizing feed quality and minimizing the impact of raw‑material variability on product performance.
Weighing accuracy is another area that remains to be developed. Currently, several micro‑ingredient systems are available that measure by weight loss. This weight‑loss approach eliminates the influence of airflow, enhances weighing precision, and enables the simultaneous measurement of ten or more materials, thereby shortening the batching cycle. Moreover, it offers high accuracy and can be integrated with mixers that operate on very short cycles.
II. Coordination between the crushing process and the batching process in the compound feed processing unit
Crushing technology is closely related to ingredient‑mixing technology. Depending on the sequence of operations, it can be categorized into two processes: mixing before grinding (referred to as “mix‑then‑grind”) and grinding before mixing (referred to as “grind‑then‑mix”). At present, the “grind‑then‑mix” process is widely adopted in China, though some feed mills also employ this approach.
The pre‑mixing process offers numerous advantages, but it also has the following drawbacks: (1) it demands a high level of automated control; (2) replacing the screen or hammer plates on the crusher necessitates shutting down downstream operations; and (3) the mill experiences periodic no‑load operation.
However, with the development of the electromechanical industry, the quality and application scope of electronic components have continued to expand, and workshop scheduling has become more rational and advanced, thereby effectively addressing these shortcomings. Meanwhile, as feed‑ingredient technologies have progressed, the use of oilseed crops such as rapeseed and sunflower seeds—rich in both oil and protein—has steadily increased. Because these oil‑rich ingredients are difficult to crush in a single pass, the practice of blending first and then milling is becoming increasingly common.
III. Ingredient-Dispensing Precision Control Technology for Compound Feed Processing Units
Employing error-free computer‑based batching control technology, the system can precisely regulate the quantity of each ingredient in every batch. A micro‑additive pre‑mixing and high‑precision micro‑mixing system has been established.
IV. Mixing in the Compound Feed Processing Unit
Mixing is a critical step in ensuring feed quality and improving feed efficiency.
1. Mixing Process

The key to the mixing process is ensuring uniformity. Three main factors are considered: mixing time, the agitator design, and measures to prevent segregation after mixing. Mixing time is typically determined based on the scale’s mixing duration.

Design the mixing time based on the recommended values provided by the manufacturer. Mixers are available in two types: large‑door and small‑door models. Large‑door mixers discharge quickly and minimize residual material; however, they may leak if the door does not seal properly, compromising the quality of the mix. Therefore, this factor should be carefully considered when selecting a mixer. To minimize segregation of the mix, the conveying distance after discharge should be kept as short as possible. In particular, pneumatic conveying should be avoided, and the rate at which material enters the storage bin should not be too high. Additionally, a pre‑mixing stage should be incorporated into the mixing process.

2. Hybrid Processing Equipment
The research focus in the field of mixing equipment is primarily on enhancing mixing uniformity, reducing mixing time, and increasing throughput per unit time. There are numerous types of agitators; the most commonly used include horizontal ribbon mixers, horizontal paddle mixers, and horizontal twin‑shaft paddle mixers (such as the Föbauer mixer). The mixing performance of various mixers is summarized in the table below:

For both compound and specialized feed mills, the choice of mixer output deserves careful consideration. Single‑product feed mills tend to employ a single high‑capacity mixer (12–15 t/h), whereas compound feed mills, to enhance production flexibility, should use smaller, short‑cycle mixers (1–4 t/h) to produce the diverse, small‑batch formulations required by customers.