The core quality indicator of BB fertilizer (blended fertilizer) is nutrient uniformity, and the mixing performance of the BB fertilizer mixer directly determines the quality of the final product. This process is influenced by several key factors and requires targeted control.

First, the raw material pretreatment stage. BB fertilizer raw materials are mostly nitrogen, phosphorus, and potassium single granular fertilizers or powdered organic fertilizers. If the raw material particle size varies greatly, stratification due to different densities is likely to occur. Screening is required to control the raw material particle size deviation to within 2mm. At the same time, the raw material moisture content must be maintained at a stable 12%-15%. Too high a moisture content can easily cause the particles to stick together, while too low a moisture content can cause the powdered raw material to generate dust.

Second, the mixing parameter setting is important. The speed of the BB fertilizer mixer should be adjusted according to the raw material type. When mixing granular fertilizer, the speed can be set to 15-20 rpm to avoid particle collision and breakage caused by high speed. When mixing raw materials containing powder, the speed can be increased to 20-25 rpm. The mixing time also needs to be controlled. Typically, 8-12 minutes per mixing cycle is sufficient. Too short a time will result in uneven mixing, while too long a time can easily cause excessive friction and loss of the raw materials.

Finally, the compatibility of the equipment structure is important. The impeller design of the BB fertilizer mixer must balance convection and shearing. If the raw materials contain a small amount of fiber (such as when adding straw powder to organic fertilizer), impellers with scraping functions should be used to prevent the raw materials from adhering to the cylinder walls. The cylinder should avoid right angles and instead use rounded transitions to reduce dead corners where raw materials accumulate, ensuring that every portion of the raw materials is mixed and ensuring uniformity from a structural perspective.

In fertilizer production, ring die granulators must adjust core parameters based on the characteristics of different raw materials, such as organic fertilizer, compound fertilizer, and slow-release fertilizer, to ensure optimal granulation.

For organic fertilizers, whose raw materials often contain fiber components such as straw and fermented manure, ring die granulators require large-aperture ring dies (typically 8-12mm) and anti-entanglement rollers to prevent fiber entanglement and pelletizing stalls. Furthermore, the steam injection time should be appropriately extended during the conditioning stage to enhance the viscosity of the fiber raw material.

If producing bio-organic fertilizers containing live bacteria, a rapid cooling device should be added after granulation to reduce the pellet temperature to below 35°C to prevent high temperatures from killing the live bacteria.

Compound fertilizer raw materials are primarily nitrogen, phosphorus, and potassium powders, which are prone to moisture absorption and agglomeration. Therefore, granulators require ring dies made of wear-resistant materials (such as alloy steel) to minimize wear on the die holes, and the roller pressure must be precisely controlled. Excessive pressure can cause components like nitrate nitrogen in the raw materials to decompose and be lost due to the high extrusion temperature, while too little pressure can cause the granules to become loose.

Slow-release fertilizers, however, contain special ingredients like coating agents, so the ring die granulator requires a lower extrusion temperature (below 30°C). This is usually achieved by reducing the roller speed (from 30 rpm to 20 rpm) and adding a cooling device to prevent high temperatures from damaging the slow-release coating structure and ensure the fertilizer’s slow-release effect.

In industrial production, directly stacking high-temperature materials after processing can easily lead to problems such as agglomeration and deterioration. Drum fertilizer coolers are key equipment for addressing this problem. So how do they achieve efficient cooling? Today, we’ll examine their core operating principles from both a structural and process perspective.

The core structure of a drum fertilizer cooler consists of an inclined drum body, a transmission system, a cooling system, and a discharge mechanism. During operation, hot materials enter through the feed port at the upper end of the drum. The transmission system drives the drum to slowly rotate, causing the materials to continuously tumble and move forward within the drum as it rotates.

The cooling system achieves cooling through two methods: one is a cooling jacket installed on the drum shell, through which cold water or air flows, removing heat from the material through heat conduction; the other is a direct flow of low-temperature gas into the drum. The gas fully contacts the hot material, absorbing heat through heat exchange, and is then discharged through the exhaust port. Throughout the entire process, the material is tumbled to ensure uniform heating and avoid incomplete cooling. The drum fertilizer cooler’s tilt angle and rotational speed control the material’s residence time, allowing for flexible adjustment based on the cooling requirements of different materials.

Finally, the cooled material is discharged from the discharge port at the lower end of the drum, completing the cooling process. Whether it’s granular, powdered, or small chunks, this cooling method delivers efficient and stable cooling, widely applicable to production needs across multiple industrial sectors.

When a flat die granulator is in operation, material first enters the feed inlet and is evenly conveyed to the pulverizing unit, where it is fully pulverized to meet subsequent processing requirements. The pulverized material is then transported by a screw conveyor to the pressing area. In the pressing area, the pressing rollers work closely with the flat die, forcing the material through the die holes under strong pressure, initially forming pellets. Next, the pellets are cut into the desired length by a cutter and leave the pressing area. The hot pellets then enter the cooling unit, where they are rapidly cooled by air or water, stabilizing their shape and properties. Finally, the cooled pellets are screened and packaged before being released to the market as finished products.

The flat die granulator’s pressing rollers feature wide grooves, ensuring pressure resistance and wear resistance. The larger rollers can withstand greater pressure, while the wider grooves effectively prevent material accumulation and ensure smooth material flow into the pressing area. The evenly distributed design of multiple pressing rollers ensures smoother operation while increasing the pressing area, significantly improving production efficiency. Taking biomass pellet production as an example, this design can increase yields by 30%-50%, effectively reducing production costs.

The flat die granulator achieves efficient material forming through its ingenious structural design and scientific workflow. Currently, this principle is widely used in feed, biomass energy, fertilizer, and other fields. With continued technological advancement, it is expected to play a significant role in even more areas in the future, bringing greater convenience and benefits to industrial production and resource utilization.