Vertical Disc Mixer

Equipment Introduction

The vertical disc mixer is a new type of vertical continuous mixing equipment, mainly used for the uniform mixing of powdery and granular materials. Its core design concept utilizes the mixing mechanism within the disc to generate three-dimensional tumbling motion, enabling raw materials with different specific gravities and particle sizes to achieve a high degree of homogenization in a short time. This equipment features a compact structure, small footprint, low energy consumption, high mixing efficiency, and continuous operation, and is widely used in industries such as organic fertilizer, compound fertilizer, chemicals, building materials, and feed.

Compared to horizontal twin-shaft mixers, vertical disc mixers have a lower investment threshold for small- to medium-scale production scenarios. Furthermore, their open or semi-open structure allows operators to observe the material status in real time, making them an economical link between crushing, screening, and granulation processes.

Equipment Structure

The entire machine can be divided into three core parts, each working collaboratively to ensure a stable and efficient mixing process:

1. Frame: The frame is the load-bearing foundation of the entire machine, typically constructed from high-quality carbon steel plates and channel steel, undergoing rigorous product certification and process inspection to ensure structural stability under high loads.
2. Transmission Connection: Composed of a motor, a cycloidal pinwheel reducer, and nylon pin couplings. The cycloidal pinwheel reducer offers advantages such as a large transmission ratio, compact structure, smooth operation, and low noise; the nylon pin couplings facilitate assembly and maintenance while also providing some cushioning and vibration damping.
3. Mixing Part: Includes a mixing disc, mixing shaft, mixing arms (or mixing teeth/blades), inlet, and outlet. Fixed mixing teeth are mounted on the mixing shaft, rotating to evenly tumble the material within the disc. The inner wall of the disc is typically lined with polypropylene or stainless steel plates, offering non-stick and wear-resistant properties, significantly reducing material residue. In addition, some models are equipped with atomizing nozzles at the top, which can evenly spray liquid bacterial agents or binders during the mixing process; the bottom discharge port is equipped with pneumatic or manual valves to achieve rapid unloading.

Application scope of equipment

Working Principle of the Equipment

The core working principle of the vertical disc mixer lies in the combination of “centrifugal dispersion” and “gravitational diffusion.”

1. Power Transmission and Rotation

The electric motor drives a high-torque cycloidal pinwheel reducer, which in turn drives the main shaft. The main shaft then drives the mixing teeth to agitate the material. The main body of the equipment is a vertically placed rotating disc with several sets of lifting plates arranged at specific angles at the bottom.

2. Material Lifting and Dispersion

When the motor drives the disc to rotate at high speed, the material falls into the disc from the top inlet and is instantly lifted to a high position by the lifting plates. Then, under the influence of gravity, it falls in a parabolic trajectory. During this process, tens of thousands of collisions, interpenetration, and diffusion occur between the material particles.

3. Three-Dimensional Mixing

The material forms a complex vortex motion within the disc, achieving all-round tumbling and mixing from bottom to top and from the inside out. Unlike horizontal mixers that rely on forced shear convection, vertical disc mixers utilize a vertically rotating disc design to create intense relative motion between raw materials of different specific gravities and particle sizes in three-dimensional space.

4. Mixing Completion and Discharge

A batch of material typically completes mixing in 3–8 minutes. After mixing, the material is rapidly discharged from the bottom outlet, and a pneumatic butterfly valve enables rapid unloading.

5. Key Process Parameters

The linear velocity of the mixing teeth should be controlled between 3–5 m/s—too high a velocity will cause fine powder to adhere to the wall and splash, preventing it from falling; too low a velocity will result in insufficient shear force to break up wet clumps. The coefficient of variation (CV) of mixing uniformity should be controlled within 5%.

Applicable Raw Materials for the Equipment

1. Fertilizer Industry (Main Application)

1) Organic Raw Materials: Well-rotted chicken manure, pig manure, sheep manure, straw powder, mushroom residue, sludge, biogas residue, garden leaves;

2) Inorganic Fertilizers: Urea, monoammonium phosphate, diammonium phosphate, potassium chloride, potassium sulfate, calcium magnesium phosphate fertilizer, trace element powders;

3) Auxiliary Materials: Humic acid, microbial agents, binders, conditioners;

4) Suitable Moisture Content: 20%~35% Suitable for mixing with semi-wet viscous materials and dry powdered fertilizers.

2. Raw Materials for Other Industries

Feed: Soybean meal, wheat bran, fish meal, premix additives;

Building Materials: Dry mortar, bentonite, clay, gypsum powder;

Chemical Industry: Lightweight powder fillers, composite additives, powdered chemical raw materials; Restrictions: Large stones, metal blocks, and hard, large materials are prohibited from direct feeding, as they may damage the mixing teeth.

Equipment operation and maintenance methods

Common Equipment Faults and Solutions

Fault 1: Abnormal operating noise, metallic friction and impact sounds

Causes: Loose stirring tooth bolts, hard iron blocks/stones entering the disc, insufficient lubrication and wear of bearings, misalignment of the main shaft;

Solution: Immediately stop the machine and disconnect the power; open the cover and clean out hard debris; tighten the stirring tooth bolts; add grease to the bearings, replace worn bearings directly; correct the coaxiality of the main shaft.

Fault 2: Discharge blockage, slow discharge

Causes: High moisture content of material, high viscosity and clumping; insufficient opening stroke of the discharge gate; material accumulation at the discharge port;

Solution: Stop the machine and use plastic/wooden tools to clean the blockage (do not use iron tools to scratch the liner); adjust the discharge gate limit switch; clean the accumulated material at the discharge port every shift; for high-moisture materials, appropriately reduce the feed rate and shorten the single mixing time.

Fault 3: Motor overload, tripping, and difficulty starting

Causes: Starting with material; accumulated material in the disc; increased resistance due to wear of the mixing teeth; insufficient lubrication in the reducer; unstable voltage;

Solutions: Strictly follow the no-load start procedure; thoroughly clean the disc; replace worn mixing teeth; replenish reducer lubricating oil; stabilize the power supply voltage.

Fault 4: Main shaft seal leakage and dust overflow

Causes: Aging of the packing seal, blockage of the labyrinth groove; excessive feed dust;

Solutions: Replace the sealing packing, clean the labyrinth groove of accumulated dust; install a dust removal device for the feed to reduce dust generation.

Fault 5: Poor mixing uniformity and material stratification

Causes: Severe wear of the mixing teeth, insufficient number of layers; excessive feed speed, insufficient material mixing time; mismatched speed;

Solutions: Replace the entire set of mixing teeth; reduce the feed flow rate; for frequency converters, adjust the speed downwards/upwards to match the material characteristics; extend the single mixing time.

Fault 6: Gearbox overheats too quickly and leaks oil.

Causes: Insufficient/deteriorated lubricating oil; stuck or overloaded coupling pins; aging oil seals.

Solutions: Replace gear oil; inspect coupling pins; replace gearbox oil seals.

Application of the Equipment in the Production Line

In a complete organic fertilizer or compound fertilizer production line, the vertical disc mixer is typically located after the crushing and screening process and before the granulator, undertaking the core functions of “pre-mixing” and “wetting and conditioning”:

1. Batching and Mixing Hub: Receives various raw materials (nitrogen, phosphorus, potassium, organic fertilizer powder, recycled materials, etc.) from the dynamic batching machine, and performs batch homogenization mixing to ensure nutrient stability and avoid local enrichment.
2. Process Connection: The uniformly mixed material is conveyed by a belt conveyor to the granulator (such as a rotary drum granulator, disc granulator, or extrusion granulator), providing a consistent material base for subsequent granulation.
3. Liquid Addition: Water, steam, microbial agents, or binders can be sprayed simultaneously during the mixing process to adjust the material moisture and improve the granulation pelleting rate.
4. Reuse of Recycled Materials: The dried and cooled recycled materials are re-mixed into the raw materials, achieving a closed-loop cycle and reducing raw material waste.

Equipment Parameters

Target Customers for Equipment:

1. Fertilizer Production Enterprises:

Small and medium-sized organic fertilizer plants, bio-organic fertilizer processing plants;

BB fertilizer blending stations, organic-inorganic compound fertilizer plants;

Livestock and poultry manure resource utilization enterprises, sludge treatment plants.

2. Raw Material Processing Supporting Manufacturers:

Feed premix plants, small dry powder mortar processing plants, garden waste treatment stations.

3. Engineering Supporting Customers:

Organic fertilizer equipment manufacturers, organic fertilizer production line planning and design institutes, small township agricultural input processing plants.

4. Core Customer Characteristics:

Small and medium-sized production entities with limited site area, moderate budgets, frequent fertilizer formula changes, high requirements for mixing uniformity, and daily production capacity of 10-200 tons.

Equipment Limitations and Selection Considerations

1. Limitations: Not suitable for long-term mixing of ultra-high viscosity slurries and large-particle lumps; for ultra-high capacity (over 20t/h) continuous production lines, a twin-shaft horizontal mixer is preferred.
2. Selection Points:

1) High-moisture organic fertilizer materials: Stainless steel lining and thickened wear-resistant mixing teeth are preferred.

2) Frequent switching between multiple formulas: Select models with large side access doors and easily removable lining plates.

3) Automated production lines: Optional variable frequency motors, pneumatic unloading, and remote control modules are recommended.

4) Corrosive chemical raw materials: Custom-made 304 stainless steel model.