Objective: To remove dust, sand, small stones, metal shavings, and other impurities attached to or mixed with dried stems, leaves, flowers, and roots, while maintaining the integrity of the plant material and avoiding breakage.

Challenge: Dried plants are fragile and cannot be washed vigorously with water (unless a subsequent drying process is included). Therefore, the main methods used are physical sorting and airflow cleaning.

Common Cleaning and Sorting Equipment

1. Air Separation Cleaning Machine / Airflow Cleaning Machine

Working Principle: A controlled airflow (blower) is used to blow the lighter dried herbal plants into a collection bin, while heavier impurities such as stones, metals, and soil particles fall due to gravity and are separated through different channels.

Advantages:

Waterless dry cleaning, keeping the plants dry and preventing mold.

Efficient removal of impurities with higher specific gravity.

Minimal physical damage to the plants.

Applicable to: Most dried herbs, including leaves, flowers, and cut roots and stems.

2. Vibrating Screen Separator / Multi-layer Screening Machine

Working Principle:  Multiple layers of vibrating screens with different mesh sizes are used to classify materials by size. Small particles of sand and soil fall through the bottom screen, stones and larger impurities remain on the upper screens, and the clean herbal plants remain on the middle screen.

Advantages:

Can simultaneously separate multiple impurities by size.

Screen mesh size can be customized to suit different herbal material sizes.

Applicable to: Granular, seed-like, or uniformly cut herbal materials.

3. Specific Gravity Separator / Density Separator

Working Principle: Combining vibration and upward airflow, the material is made to "boil" on the screen surface. Denser stones and metals sink and move towards the higher end of the screen; lighter herbal plants float and move towards the lower end, thus achieving precise separation.

Advantages:

Extremely high separation accuracy, especially effective at separating impurities that are similar in size and shape to the herbs but have different densities.

A key piece of equipment in the processing of traditional Chinese medicine and high-end spices.

Applicable to: High-value, dried herbal raw materials requiring sophisticated processing. 

4. Rotary Drum Cleaning/Polishing Machine (Optional)

Working Principle: Dry herbs tumble and rub against each other inside a slowly rotating mesh drum, aided by a powerful dust collection system, to remove surface dust and thin layers of soil.

Note: This equipment is primarily used for surface dust removal and polishing. It has limited effectiveness against embedded or large impurities and is typically used as a pre- or post-processing step.

Application: Suitable for raw materials requiring improved appearance and removal of surface dust.

5. Magnetic Separator

Working Principle: Powerful magnets (permanent magnets or electromagnets) are installed on the conveyor belt or discharge port to attract and remove magnetic metal impurities such as nails, screws, and metal shavings that may be mixed in with the raw materials.

Advantages: Low cost, easy installation, and an essential process for ensuring safety (preventing damage to subsequent equipment) and product purity.

Application: Standard configuration for all dry herbal product processing lines.

Typical Processing Line Combination

For large-scale processing, equipment is usually combined into a processing line to achieve optimal cleaning results:

Feeding → Magnetic Separation (iron removal) → Air Separation (removal of heavy impurities and light floating materials) → Vibrating Screen (grading and soil removal) → Gravity Separation (precise sorting) → Manual Inspection/Packaging