The core working principle of fertilizer mixing equipment, such as drum mixers or double helix mixers, is to achieve physical mixing of various granular or powdered fertilizers through mechanical stirring. The process does not involve chemical reactions and only relies on the structure and motion of the equipment to ensure mixing uniformity. The following is an explanation from three aspects: device type, structural characteristics, and working principle:

　　1、 Equipment type and typical structure

　　Drum mixer

　　Structure: Adopting a horizontal drum design, equipped with spiral blades or a three-dimensional mixing structure inside. Some high-end models use 304/316 stainless steel material to enhance corrosion resistance.

　　Auxiliary design: Optional tipping bucket automatic feeding device, steam pipeline humidity control system, supporting continuous production.

　　Applicable scenarios: Dry mixing processes such as BB fertilizer (mixed fertilizer), compound fertilizer, organic fertilizer, etc., with a single machine processing capacity of 5-20 tons/hour.

　　Double helix mixer

　　Structure: Composed of a mixing shaft, spiral blades, frame, and electrical control system, the blades form a certain angle (such as 37 °) with the axis and are set in reverse.

　　Features: Fast mixing speed, high uniformity, short feeding and discharging time, suitable for medium to large-scale production of 12 tons per hour.

　　2、 Detailed explanation of working principle

　　Drum mixer

　　Movement mode: The drum rotates at a low speed of 20-40rpm, combined with internal spiral blades or three-dimensional structures, to cause fertilizer particles to roll up and down and move axially.

　　Hybrid mechanism:

　　Gentle mixing: Low speed operation reduces particle breakage, ensures mixing uniformity, and a breakage rate of less than 3%.

　　Convection effect: Spiral blades push the material to move axially, forming a convective cycle and eliminating local concentration differences.

　　Discharge method: The mixed fertilizer is discharged through gravity or auxiliary devices (such as discharge blades).

　　Double helix mixer

　　Movement mode: When the mixing drum rotates clockwise, the high blades lift the material to a certain height and then freely fall, mixing with the bottom material; The low blades push the material at the discharge end in the opposite direction, creating strong impact and convection.

　　Hybrid mechanism:

　　Lifting and falling: High blades lift materials to increase mixing space, and the falling process enhances particle collision.

　　Bidirectional pushing: The high and low blades act in reverse to circulate the material in the mixing drum, avoiding dead corners.

　　Discharge method: When the mixing drum rotates counterclockwise, the discharge blades discharge the finished material.

　　3、 The impact of key design on the mixing effect

　　Blade angle and arrangement

　　The spiral blade angle of the drum mixer (such as 37 °) and the reverse setting of the high and low blades of the double helix mixer both improve mixing efficiency by optimizing the material movement trajectory.

　　Excessive blade angle may lead to material accumulation, while insufficient blade angle may result in insufficient hybrid power.

　　Speed control

　　The drum mixer operates at low speed (20-40rpm) to protect the integrity of the particles, while the double helix mixer achieves rapid mixing through high-speed rotation (such as 14.5-12.5 revolutions per minute).

　　The rotational speed should be adjusted according to the characteristics of the material, such as particle size and density, to avoid layering or excessive crushing.

　　Material selection

　　Stainless steel materials (such as 304/316) are suitable for fertilizer mixtures containing corrosive components (such as potassium phosphate), while carbon steel is used in general scenarios to reduce costs.