Horizontal Mixer

Horizontal Mixer

The horizontal mixer is a material mixing device featuring a horizontally mounted U-shaped vessel as its core container and ribbon-style mixing blades as its working components. It is widely used across industries such as chemicals, food processing, pharmaceuticals, animal feed, and fertilizers for mixing powders, granules, and viscous materials. In fertilizer production, the horizontal mixer serves as the key equipment for the batch homogenization of multi-component materials in production lines for organic fertilizers, compound fertilizers, blended fertilizers, and feed premixes.

The design philosophy of the horizontal mixer centers on high capacity, high efficiency, and ease of integration into production lines. Its elongated U-shaped vessel structure ensures that materials move with minimal resistance during the mixing process. Counter-rotating ribbons mounted on a single horizontal shaft create a mixing environment that is both energy-efficient and highly effective. The ribbon blades typically feature a double- or triple-layer configuration: the outer helix gathers material from the ends toward the center, while the inner helix conveys material from the center toward the ends. This flow pattern generates multiple eddies, accelerating the mixing process and enhancing uniformity. The unit is driven by a cycloidal reducer powered via a pulley system; unlike the rigid high-torque transmission of gear reducers, the elastic connection provided by the belt drive offers the advantage of protecting transmission components during overload conditions.

In fertilizer production lines, the horizontal mixer is typically positioned after the crushing and screening stages but before the granulator. It precisely homogenizes pulverized organic powder, NPK fertilizer powders, medium and trace elements, and microbial agents. By supplying raw materials with stable properties and uniform nutrient distribution to the granulation stage, it directly influences granule formation rates and particle strength. Thanks to its rapid mixing speed, high uniformity, absence of dead zones, and minimal material residue, the horizontal mixer has become indispensable core equipment in the fertilizer processing industry.

Overall Structure and Core Components

The horizontal mixer features a modular, integrated design, with the complete unit comprising the following six major systems:

(I) Mixing Chamber System: This serves as the main vessel and utilizes a long U-shaped structure. This design ensures that materials move within the chamber with minimal resistance. The chamber can be customized with heating or cooling jackets to meet specific process requirements, such as vacuum or positive-pressure operation. To prevent material adhesion, the inner walls can be fitted with rubber liners; for fertilizer raw materials—which are often highly moist and sticky—liners made of 304 stainless steel or high-molecular-weight polyethylene are commonly used to provide corrosion resistance and prevent sticking. Inspection ports on both sides facilitate routine maintenance.

(II) Agitation System: This is the core working component, consisting of a horizontal main shaft and ribbon-style mixing blades mounted upon it. The ribbon blades are typically arranged in double or triple layers: the outer helix gathers material from both ends toward the center, while the inner helix conveys material from the center toward both ends. This counter-directional ribbon layout creates convective mixing, enhancing both mixing speed and uniformity through a vortex effect. The mixing components are manufactured from highly wear-resistant steel. Given the characteristics of organic fertilizer raw materials, the edges of the ribbon blades are often hard-faced with wear-resistant alloys to withstand abrasion from grit.

(III) Drive System: This system comprises an electric motor, pulleys, and a cycloidal reducer. A pulley-driven arrangement transmits power to the cycloidal reducer; the elastic nature of the belt drive offers the advantage of protecting drive components during overload conditions. The motor is directly coupled to the main mixing shaft via the cycloidal reducer, resulting in a simple structure, high operational reliability, and ease of maintenance. Some high-end models are equipped with a variable-frequency drive (VFD) system, allowing the main shaft speed to be flexibly adjusted based on material viscosity.

(IV) Shaft End Sealing System: Gland packing seals are installed at the shaft ends to minimize leakage. A high-efficiency labyrinth air-purge seal ensures zero material leakage at the shaft ends. To address the tendency of fine fertilizer powders to leak, the bearing housings feature a double-face seal design.

(V) Discharge System: The discharge method is selected flexibly based on the specific characteristics of the materials being processed. For powdery materials, a pneumatic large-opening door design is employed, offering advantages such as rapid discharge and zero residue. The bottom is equipped with a pneumatic or manual large-opening curved discharge gate; with a discharge angle exceeding 70 degrees and the aid of the ribbon agitator's reverse thrust, the material can be completely emptied within 3 to 5 seconds. The residual rate is less than 0.5%, effectively preventing cross-contamination between different formulation batches. Manual or pneumatic butterfly valves are used for ultra-fine or semi-fluid materials.

(VI) Auxiliary Systems: These include a top feed inlet; a liquid addition device (featuring top-mounted atomizing nozzles for the uniform spraying of liquid microbial agents or binders); and a heating or cooling jacket (offering options for electric or thermal oil heating, while cooling can be achieved by directly injecting cooling water into the jacket), among others.

Applicable Fields and Industry Coverage

Horizontal mixers have an extremely wide range of applications, covering virtually every industrial sector that requires the mixing of powders, granules, and viscous materials.

Fertilizer Production: Serves as core equipment for the batch homogenization of multi-component materials in production lines for organic fertilizers, compound fertilizers, blended fertilizers, bio-fertilizers, organic-inorganic compound fertilizers, and feed premixes. Capable of mixing powder-with-powder and powder-with-liquid combinations; suitable for blending various fertilizer raw materials such as organic fertilizers, potting soil, and compound fertilizers.

Chemical Industry: Widely used for mixing powders and liquids in sectors such as fine chemicals, plastics, rubber, coatings, and refractory materials. Particularly well-suited for handling viscous materials.

Food and Pharmaceutical Industries: Widely used for material mixing in the food, pharmaceutical, cosmetics, and additive industries.

Feed Industry: Widely used for mixing applications in the feed and feed additive sectors.

Construction Materials Industry: Widely used for mixing raw materials such as thermal insulation mortar, wear-resistant flooring, putty, natural stone-effect paint, and gypsum.

Types of usable raw materials

Horizontal mixers can process a wide variety of raw materials. Fertilizer materials: organic fertilizer powder, NPK chemical fertilizer powder, compound fertilizers, blended fertilizers, bio-organic fertilizers, nutrient-rich soil, humic acid, peat, secondary and trace elements, microbial inoculants, etc. Chemical raw materials: titanium dioxide, calcium carbonate, ethyl cellulose, chemical additives, bentonite, etc. Food and pharmaceutical materials: food additives, traditional Chinese medicinal herbs, flavors and fragrances, etc. Construction material ingredients: thermal insulation mortar, wear-resistant flooring, putty, natural stone-effect paint, gypsum, etc.

Operating Principles and Mixing Mechanisms

The working principle of the horizontal mixer relies on the synergistic effect of "dual-layer ribbon convective circulation" and "three-dimensional compound motion." Its operation involves three core stages:

Axial Convection Stage: As the main shaft rotates, the inner ribbon drives material toward both ends, while the outer ribbon drives material from the ends toward the center. The outer ribbon gathers material from the sides to the middle, and the inner ribbon conveys material from the middle to the sides, creating a vigorous axial convective circulation.

Radial Tumbling Stage: The front face of the ribbon pushes material along the helical path, while the voids formed behind the ribbon are filled by material falling from above. Driven by the ribbons, the material moves both axially and radially, establishing a convective cycle. Combined with the shearing and radial tumbling actions exerted by the ribbon edges, the material undergoes a three-dimensional compound motion within the mixing vessel.

Vortex Intensification Stage: The counter-movement of the inner and outer ribbons generates multiple vortices within the flowing material, accelerating the mixing process and enhancing uniformity. This creates an omnidirectional mixing cycle—up, down, left, and right. Even when materials differ in specific gravity or particle size, the rapid, vigorous tumbling and scattering action of the staggered mixing ribbons ensures excellent mixing results.