Horizontal Mixer

The horizontal mixer is a core piece of equipment responsible for the batch homogenization of multi-component materials in production lines for organic fertilizers, compound fertilizers, and feed premixes. Featuring a horizontal U-shaped vessel and a double-layer counter-rotating ribbon agitator, the machine achieves rapid and uniform material blending through a three-dimensional compound motion. Within the overall fertilizer production line, the horizontal mixer is typically positioned after the crushing and screening stages and before the granulator; it precisely homogenizes pulverized organic powder, NPK chemical fertilizer powders, medium and trace elements, and microbial agents, thereby supplying the granulation process with raw materials that possess stable properties and uniform nutrient distribution. The mixing performance directly determines the granulation rate and granule strength, making this mixer a critical link connecting the upstream and downstream stages of fertilizer production.

Component Composition and Functional Zoning

From the perspective of fertilizer production processes, the horizontal mixer comprises the following functional units:

(I) Feeding Unit: Includes a top feed inlet and a liquid addition system. Atomizing nozzles at the top ensure the uniform spraying of liquid microbial agents or binders. The feeding sequence follows the principle of loading heavier materials before lighter ones and dry materials before wet ones.

(II) Mixing Unit: This is the core component of the equipment, featuring a horizontal main shaft and dual-layer (inner and outer) counter-rotating ribbon blades. The outer ribbon conveys material from the ends of the mixing vessel toward the center, while the inner ribbon simultaneously conveys material from the center toward the ends. Combined with the shearing and radial tumbling actions of the blade edges, this configuration enables the material to undergo complex three-dimensional motion, achieving a complete mix within 3 to 8 minutes.

(III) Discharge Unit: Includes a curved bottom discharge outlet and a large-opening mechanism (pneumatic or manual). The discharge angle exceeds 70 degrees, allowing for complete material evacuation within 3 to 5 seconds, aided by the counter-thrust of the ribbon blades.

(IV) Power and Control Unit: Includes the electric motor, gear reducer, and variable frequency drive (VFD) system.

Production Line Roles and Process Flow

The horizontal mixer serves as the core mixing component in a fertilizer production line. The complete production process flows as follows: raw material crushing → screening → horizontal mixing → granulation → drying → cooling → screening → packaging.

During the mixing stage, the horizontal mixer performs several critical tasks: precisely blending pulverized organic powder with NPK chemical fertilizer powders according to the formula; uniformly dispersing trace components—such as secondary nutrients, micronutrients, and microbial agents—into the bulk material; evenly spraying liquid microbial agents or binders via top-mounted atomizing nozzles; and supplying raw materials with stable properties and uniform nutrient distribution to the granulation stage. Compared to vertical mixers, horizontal mixers offer faster mixing speeds, eliminate dead zones, and minimize material residue, making them particularly well-suited for processing formulations that involve materials with significant differences in specific gravity or require the addition of trace microbial agents.

Description of Hybrid Processes and Stages

The mixing process of the horizontal mixer can be divided into the following stages:

Feed distribution stage: Materials are introduced through the top inlet, following a sequence of heavy-to-light and dry-to-wet. Liquid microbial agents or binders are evenly sprayed in via top-mounted atomizing nozzles. Feeding should be performed slowly and steadily; rapid, bulk dumping must be avoided.

Convective mixing stage: Once the main shaft rotates, the outer ribbon pushes material from both ends of the mixing vessel toward the center, while the inner ribbon simultaneously conveys material from the center back toward the ends. This creates a vigorous axial convective circulation. The front face of the ribbon drives the material along the helical path, while the voids formed behind the ribbon are filled by material falling from above.

Three-dimensional homogenization stage: Combined with the shearing and radial tumbling actions exerted by the blade edges, powdered or granular raw materials undergo a complex three-dimensional mixing motion within 3 to 8 minutes. The coefficient of variation (CV value) for mixing uniformity can be consistently maintained below 5%.

Discharge stage: Upon completion of mixing, the large pneumatic bottom discharge gate opens, and the material is completely evacuated within 3 to 5 seconds, aided by the reverse thrust of the ribbons.

Preparation and Requirements for Pre-production Materials

Horizontal mixers have specific process requirements for feed materials. Particle size: The particle size of the materials to be mixed should range from 20 to 1400 mesh. Material characteristics: Mixing parameters must be adjusted based on factors such as material density, particle size, and flowability. Liquid addition: For solid-liquid mixing, the machine should be started before the liquid is sprayed; mixing should continue for 3 to 5 minutes after spraying is complete. Spray volume: This is determined based on the material's adsorption properties and specific production process requirements.

Operating procedures and key control points

Standard operation of horizontal mixers is the key to ensuring mixing quality and equipment life:

Preparation before starting: Check whether the bolts in various parts are loose and whether the main engine compartment door is tight. Fill the reducer with oil (gear oil) according to the oil mark before use.

Operation: Plug in the power first, then turn on the switch. During the mixing process of materials, no hard foreign objects larger than 5mm shall enter the machine. The mixing time of one material is generally about 5 to 8 minutes.

Shutdown operation: When the machine is shut down and not in use, the materials in the machine should be drained cleanly. If abnormal sounds such as metal collision or friction are found, stop the machine immediately and check to eliminate them.