Multiple Silos Single Weigh Static Automatic Batching System

Equipment Introduction

The multi-silo single-weighing batching system, also known as a multi-silo single-weighing batching machine, uses a shared independent weighing hopper for multiple raw material storage silos to accumulate and meter the materials. It is a batch-type static batching equipment, specifically designed for small and medium-sized organic fertilizer and BB blended fertilizer plants. Unlike single-silo single-weighing systems, its core feature is that multiple raw materials are sequentially fed into the same weighing hopper to complete the overall batching. It boasts low overall cost, compact footprint, and requires fewer units.

(I) Core Advantages and Disadvantages

1. Advantages

1) Low cost and small footprint: Only one set of weighing sensors and hoppers is needed, saving 40% of equipment investment compared to single-weighing systems with the same number of silos; suitable for small workshops.

2) Simple structure and easy maintenance: Only one set of weighing components, few vulnerable parts, and low maintenance workload.

3) Modular silo structure: 3-12 raw material silos can be freely added or removed, adaptable to 3-8 kinds of fertilizer raw material formulas.

4) Integrated dust removal: Only one centralized dust removal system is used, with simple pipeline layout.

5) Easy operation: Single set of weighing instruments, low learning curve for operators. 2. Shortcomings

1) Cumulative metering has an accumulated error, with an overall accuracy of ±0.3%~±0.8%, lower than the ±0.2% accuracy of a single bin and single scale;

2) Batch-based intermittent production cannot simultaneously feed multiple raw materials, resulting in slow batching speed;

3) Blockage in a single bin can lengthen the entire batching cycle, and there is no independent isolation and maintenance function;

4) Frequent formula switching can easily lead to residual cross-contamination, resulting in a larger cleaning workload.

(II) Model Differentiation

1. Granule-Specific Model: Each bin is equipped with an electromagnetic vibrating feeder, suitable for urea and compound fertilizer granules;

2. Powder-Specific Model: The bottom of the silo is equipped with a variable frequency screw feeder + vibration arch breaker, suitable for humic acid and organic fertilizer powder;

3. General-Purpose Mixed Model for Granules and Powders: A combination of screw feeders in some bins and vibration feeders in others.

Structural Composition

The entire equipment adopts a modular design, mainly composed of the following five parts:

1. Raw Material Storage Bin Group

Number of bins: Standard configuration 3-8, can be customized to more than 10 bins depending on the complexity of the formula.

Single bin volume: Typically 1-3 m³, bin bodies are made of carbon steel or stainless steel (304/316L).

Auxiliary devices: Pneumatic arch breakers or vibrators are installed on the bin walls to prevent powdery and wet materials from bridging and clumping; dust collection ports are installed on the bin tops to connect to the workshop dust collection system.

2. Feeding Mechanism

Each bin is equipped with an independent feeding device, selected according to the material characteristics:

1)Belt feeder: Suitable for dry granules with good flowability (such as urea, potassium chloride);

2)Screw feeder (auger): Suitable for powdery and small granular materials, the feeding speed can be precisely controlled by frequency conversion speed regulation;

3)Vibrating feeder: Suitable for organic fertilizer raw materials that are prone to sticking to the walls and have high moisture content.

3. Single Weighing Unit

Weighing Hopper: Located centrally below all hoppers, suspended installation, capacity 500–1500 kg/batch.

Weighing Sensors: Equipped with high-precision resistance strain gauge sensors (typically 3–4), accuracy class C3, batching error controlled within ±0.1%–±0.3%.

Discharge Gate: Pneumatic butterfly valve or flap valve at the bottom of the weighing hopper, automatically opens for discharge after weighing reaches the target.

4. Mixing and Conveying System

Mixing Silo/Buffer Hopper: Receives weighed materials for brief premixing;

Belt Conveyor: Transports the batched materials to the next process (mixer, granulator, or packaging machine).

5. Control System

PLC + Touch Screen/Industrial Computer: Enables formula management, automatic sequential control, real-time weight display, and fault alarms.

Software Functions: Supports storage of dozens to hundreds of formulas, one-click switching; features automatic drop compensation, out-of-tolerance alarm, data recording, and report output functions.

Working Principle
The multi-silo single-weighing batching machine adopts the static incremental weighing (Gain-in-Weight) principle. The workflow is as follows:

1. Formula Setting: The operator selects the formula on the touchscreen, setting the target weight and batching order for each raw material.

2. Sequential Feeding: The control system starts the feeder of the first silo in the preset sequence, and the material enters the weighing hopper. The feeding process is divided into two stages:

1) Coarse Flow (Fast Feed): Rapidly feeds to 90% of the target weight;

2) Fine Flow (Slow Feed): Automatically reduces speed when approaching the target value, accurately replenishing material with a small flow rate to reduce overshoot.

3. Metering and Locking: After reaching the set weight, the feeder stops, and the pneumatic gate closes. The system reads and records the stable weight.

4. Circular Batching: Repeat the above steps for the second, third, and so on raw materials, accumulating the weight of all raw materials in the weighing hopper.

5. Unloading: After all raw materials have been batched, the bottom door of the weighing hopper opens, and the material falls into the mixing bin below or is conveyed out via belt conveyor to the next process.

6. Zeroing and Resetting: After unloading, the weighing hopper is zeroed, and the next batch batching begins.

Application Scope and Applicable Raw Materials

1. Application Scope

Organic Fertilizer: Precisely proportioned blends of fermented livestock and poultry manure (chicken, cow, pig manure) powder, microbial agents, humic acid, wood ash, and straw powder;

Compound/Mixed Fertilizer: NPK formulation of urea, monoammonium phosphate, potassium chloride, potassium sulfate, and fillers (bentonite, attapulgite);

BB Fertilizer (Blended Fertilizer): Proportional blending of various finished granular fertilizers;

Feed Industry: Multi-ingredient formulation of livestock and poultry feed and aquatic feed;

Building Materials and Chemicals: Ingredients for concrete mixing plants, refractory materials, and dry mortar.

2. Characteristics of Applicable Raw Materials

Equipment Applications in Production Lines

(I) Complete Fertilizer Process Chain

Raw material bucket elevator → Multi-silo single-weighing batching system → Horizontal mixer → Granulator / BB fertilizer packaging machine → Drying, cooling, and screening → Finished product packaging

(II) Application Logic

1. Main batching equipment for small and medium-sized fertilizer plants, preferred for those with limited budgets and small plant spaces;

2. Standard equipment for BB blended fertilizer production lines, suitable for scenarios with 3-6 types of raw materials and moderate requirements for proportioning accuracy;

3. Batching for small organic fertilizer granulation lines, mixing and proportioning organic matter, nitrogen, phosphorus, and potassium auxiliary materials;

4. Not suitable for high-end water-soluble fertilizers and precision slow-release fertilizers (cumulative errors affect nutrient compliance).

(III) Comparison with Single-Silo Single-Scale Selection

1) Annual production below 100,000 tons, ≤6 types of raw materials, limited budget: Choose multi-silo single-scale;

2) Annual production above 100,000 tons, frequent switching of multiple formulas, and stringent nutrient indicators: Choose single-silo single-weighing batching system.

Common Faults, Causes, and Standardized Solutions

Target Audience and Selection Recommendations

1. Main Target Audience

Small and medium-sized organic fertilizer plants: Annual production of 10,000-50,000 tons, with diverse raw materials and frequent formula changes, prioritizing cost-effectiveness;

Compound fertilizer/BB fertilizer manufacturers: Require precise control of NPK ratios to meet national nutrient content standards;

Feed processing plants: Precise formulation of multiple raw materials (corn, soybean meal, premix, additives);

Blended fertilizer (BB fertilizer) distributors: Flexible formulation of different contents based on orders, multi-variety small-batch production;

Start-up fertilizer companies: Limited budget, hoping for a single set of equipment to handle both organic and compound fertilizer production.

2. Core Selection Principles

Select the number of compartments based on formula complexity: 4 compartments for conventional formulas with 3-4 raw materials; 6-8 compartments for complex formulas (including trace elements and microbial agents).

Select the feeding method based on material characteristics: Belt feed for granular feed; variable frequency screw feed + arch-breaking device for powdery/wet feed.

Select sensors based on accuracy requirements: ±0.3% for ordinary organic fertilizers; ±0.1% for compound/BB fertilizers, with automatic drop compensation.

Select models based on production capacity: PLZ1000 for 10,000–30,000 tons/year; PLZ1200 for 30,000–50,000 tons/year; PLZ1500 or dual systems in parallel for over 50,000 tons/year.

In summary, the multi-silo single-weighing batching machine, with its core logic of "multi-silo storage, single-weighing, sequential batching, and automatic accumulation," significantly reduces equipment investment and floor space while ensuring batching accuracy. Mastering its two-stage feeding control principle of "coarse flow + fine flow" and establishing a maintenance system of "daily cleaning, weekly calibration, and monthly upkeep" are crucial for ensuring formula stability and achieving the required finished product qualification rate.