Scraper Conveyor (Drag Chain Conveyor)

The Enclosed and Versatile Solution for Dust-Free, Horizontal to Inclined Conveying

The Scraper Conveyor, also known as a Drag Chain Conveyor, is a highly versatile, enclosed conveying system designed to handle a wide range of bulk materials, from fine powders to small granules, including those that are slightly abrasive or cohesive. Material is moved along a U-shaped trough by flights (scrapers) attached to a driven chain. Its enclosed design ensures dust-free operation, making it ideal for environmentally sensitive areas and for conveying materials over horizontal or moderately inclined paths, even with multiple feeding and discharge points.

Key Features

  • Enclosed Trough Design

    A sealed housing minimizes dust emission and prevents material contamination, ensuring a clean working environment and product integrity.

  • Drag Chain & Flight Assembly

    A single or double strand of heavy-duty chain with attached flights (paddles) positively drags material through the trough, providing reliable transport even with challenging materials.

  • Multiple Inlet/Outlet Flexibility

    Easily configured with multiple feed points along its length and several discharge gates, offering great layout flexibility for collecting from or distributing to several process points.

  • Horizontal & Inclined Capability

    Efficiently conveys materials at angles from horizontal up to approximately 15-20 degrees, depending on material characteristics.

  • Low Profile & Space Efficiency

    Can be installed in tight spaces, under equipment, or where headroom is limited, often requiring less space than equivalent belt conveyors.

Advantages

  • Superior Dust Containment

    The fully enclosed system is ideal for handling fine, dusty materials like powdered fertilizers, additives, or limestone, meeting strict environmental and workplace safety standards.

  • Handles Challenging Materials

    Effectively conveys moist, hot, or slightly sticky materials that might cause build-up on belt conveyors.

  • Layout Versatility

    Its ability to have multiple inlets and outlets in a single run simplifies plant design, reducing the need for multiple conveyors and transfer points.

  • Robust & Durable Construction

    Built with wear-resistant trough liners (UHMW, AR steel) and hardened chains, it withstands abrasive materials and continuous operation.

  • Gentle on Granules

    When properly designed, it can convey granular fertilizers with minimal attrition or particle degradation.

Applicable Raw Materials

  • Fine Powders

    Phosphate rock dust, limestone powder, fly ash, and powdered additives.

  • Granular Fertilizers

    NPK blends, urea prills, potash (size permitting).

  • Recycle & Byproduct Streams

    Screen fines, filter dust, and other process residues.

  • Slightly Cohesive Materials

    Damp salts, certain organic-based powders.

Basic Structure & Components

Scraper Conveyor
Enclosed Trough

A U-shaped housing, typically made of carbon or stainless steel, with optional wear-resistant liners.

Drag Chain

One or two strands of hardened steel roller chain or engineered drag chain that runs the length of the trough.

Flights (Scrapers or Paddles)

Attached to the chain at regular intervals, these push the material forward. They can be plastic, nylon, or steel.

Drive Unit

Located at the discharge end, consisting of a motor, gear reducer, and a drive sprocket assembly that engages the chain.

Take-Up Unit

Located at the tail (infeed) end, this assembly maintains proper chain tension, typically via a screw or spring mechanism.

Inlet Hoppers/Ports

Multiple openings along the top of the trough for feeding material.

Discharge Gates

Manual or automated slide gates located at the bottom of the trough for controlled material discharge.

Inspection & Access Hatches

Removable panels along the trough for cleaning, inspection, and maintenance.

Technical Data

Type

Conveyor Speed (m/s)

Capacity of the Conveyor (m³/h)

Conveying Length L0 (m)

Motor Power (kW)

MS16

0.4-0.5

2-10

3-80

0.27-11

MS20

0.4-0.5

10-15

3-80

0.4-15

MS25

0.4-0.5

15-20

3-80

0.6-18.5

MS32

0.4-0.5

20-30

3-80

1.5-30

MS40

0.4-0.5

30-40

3-80

1.5-37

MS50

0.4-0.5

40-50

5-80

2.2-55

MS63

0.4-0.5

50-60

5-80

3-75

MS80

0.4-0.5

60-80

5-80

7.5-75

MS100

0.4-0.5

80-100

5-80

11-75

 

Key Differentiators vs. Other Conveyors

A Belt Conveyor is superior for long-distance, high-capacity transport of granular materials on gentle inclines. A Scraper Conveyor excels in dust containment, handling fine/powdery materials, and complex layouts with multiple feed/discharge points in a more compact, enclosed design. It is not suitable for very long distances like belt conveyors.

A Bucket Elevator is designed for dedicated vertical lifting. A Scraper Conveyor is for horizontal to moderately inclined conveying. They serve orthogonal purposes in a plant’s material flow.

Both are enclosed. A Screw Conveyor is better for shorter distances, metered feeding, and steeper inclines but causes more particle attrition and has higher power consumption for long runs. A Scraper Conveyor is more energy-efficient for longer horizontal runs, gentler on materials, and offers easier multiple-point access.

Both are dust-tight. Pneumatic systems offer maximum layout flexibility but have very high energy costs and are best for low to medium capacities over shorter distances. Scraper Conveyors are a more energy-efficient mechanical solution for moderate distances and higher capacities where the path is relatively straight.

It is the preferred choice for clean, efficient, and flexible conveying of powders and granules within a processing plant, especially where dust control, multiple material streams, or space constraints are critical factors. It bridges the gap between simple open conveyors and high-energy pneumatic systems.