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Optical sorting technology is very useful in simplifying sorting work across various industries. However, few people know this technology very well. Because it is hard to get enough and exact information on the internet. This article will offer in-depth knowledge about this technology.

Optical sorting technology is an automatic sorting technology by comparing the optical parameters of reflected light. The minimum detecting area is closed to 0.04mm2 currently, which can support solid material sorting with a rate of 99% and over. In daily life, it is also known as color sorting technology or digital sorting technology.

Common Optical sorting technology just catches the optical information of materials’ surface. If we use an X-ray camera, then the technology can also detect inner optical information.

By optical data,  the sorting system can easily recognize wanted materials and unwanted materials.

Optical sorting technology aims at simplifying the work involved in sorting physical products. Especially, the technology is effective for solid materials. So it is commonly used to sort agricultural seeds like grains, rice, beans, and others.

Recently, most people use this technology in the plastic recycling industry, which is used to separate the PET from Abs.

Advantages of Optical Sorting Technology

Optical Sorting Technology plays a key role in ensuring efficient and accurate sorting. It’s advantages include;

1. High Efficiency

First, it is an automatic sorting technology. Take an example, we always see the people use color sorter to remove the impurities in a rice milling factory. A common one chute color sorter will sort about 500kgs of raw rice in an hour.

Also, no random mistakes will happen, which is impossible to avoid for human sorting.

Optical sorting technology ensures 100% efficiency, labor-saving, non-destructive sorting, low processing cost, etc.

2. It’s Multifunctional

Optical Sorting Technology is available for almost solid materials. And it separates the materials based on color differences.

In agriculture, It is effective to remove the impurities for all agricultural seeds. For example, we use this technology to separate over-roasted coffee beans and the well roasted.

Most tea processing factories use this technology to sort good tea leaves.

3. Accurate Sorting

According to our practical data, the sorting accuracy is close to 99% for grain and other seeds. Meanwhile, the minimum sorting area is close to 0.04mm2. That means it is easy to find all color differences.

Applications of Optical Sorting Technology

As a high precision sorting solution, we see the optical Sorting technology has a wide range of applications.

1. Agricultural Industry

As we know, optical sorting technology is very important for seed cleaning and grading. If you’d like to remove the impurities such as glass, stone, and moldy seeds, this technology is one of your best options. It is highly effective in cleaning and grading tiny seeds like sesame and beans.

Grains Take an example, Wheat. The technology can help to remove the solid impurities glass, stem, sand, and others.  It helps to remove the bad wheat seeds with aflatoxin spots, and improve food safety.
Beans Remove impurities and bad seeds, also you can use this technology to grade the beans with sizes and colors.
Rice Remove the impurities including sands, glass, shells, and other bad seeds with aflatoxins spots.
Tea Leaves Separate leaves and stem; remove the impurities, and grade the tea leaves.
Coffee Beans No matter green beans and roasted beans, the technology is effective to separate good beans and bad beans based on color differences.
Nuts Separate the fruit and shell. eg: pistachio
Vegetables Separate vegetables based on colors. eg: green pepper and red pepper.
Fruits Pick Out wanted fruits based on the sizes

In agriculture, optical sorting technology offers quality and efficiency.

2. Food Processing Industry

In food processing, you can use this technology to separate foods that are discolored and foreign materials. Also, the technology is available to use as a grading and categorization machine. It helps to separate foods that are not as ripe as desired.

CCD optical sorting technology may fit all your scenario. Some special applications like separating the fruit from the nutshells, you might also use X-ray sorting technology.

3. Plastic Recycling Industry

The optical sorting technology is also available for the plastic recycling industry. It makes plastic recycling work automatic, and easy.

There are two common usages in this field.

First, separate the plastic flasks based on color differences. Most factories mill the plastic into flakes and pellets and then use this technology to separate them into different colors.

Second, Separate the PET and HPDE. NIR color sorters are capable of sorting plastics based on their types such as PET or HPDE flakes.

4. Ore Sorting

Ore is an important building material in our daily life. So we always want to find the same color ore, and similar sizes, then optical sorting technology can easily solve this problem.

Actually it wide common in Chinese ore factories. As we know, China is the top exporter of ore building materials, and this technology is one of the main contributors.

How does this technology work?

The optical sorting technology has three main processes:

  • the Graphic Acquisition System
  • Optical Data Analysis system
  • Rejection System

Graphic Acquisition System

The acquisition system collects the optical information of the materials to be sorted. This process requires a special industrial lens. You may think this process is taking photos in our daily life.

This process will record all color details of the materials’ surface.

And this process needs a light source because color information is based on the reflected light of the materials.

Optical Data Analysis and Comparing

The data analysis process is a core part of optical sorting.

The graphics last process collected will reflect the shape, size, and color of every material. The sizes of the materials reflect light mean materials sizes. And the brightness of the reflected light of the material reflects the size of the material.

Finally, just comparing to presetting the data, then the system will decide to accept or reject the target and release the corresponding order to the next process. The whole process requires electronic signals to transport graphic information and orders which is a bridge among different parts.

For example, when the system catches an unwanted material, it will send a rejection order to the next process.

Rejection System

The rejection System is an executive system.

When receiving an acceptable order, the system will remain the motion track the same. And finally, the pellets will fly to the collecting box.

On the contrary, once receiving a rejection order, the system will release the compressed air to change the motion track and let the materials go to another collecting box.

The Rejection system work is not complicated; it follows the previous order to decide whether to keep the target or not.

What Are the Types of Optical Sorting Technology?

The optical sorting technology has three different types of cameras used in our daily uses. They are CCD Graphic Technology, NIR Graphic Technology, and X-ray Graphic Technology.

CCD Graphics Technology

CCD Graphic technology collects RGB graphic information. It is more sensitive to the material’s color. Its minimum precision is close to 0.01mm2 of the color block. This makes it ideal for sorting tiny, or different types of materials. The CCD Graphics system technology is very beneficial for you.

NIR Graphic Technology

This technology uses infrared technology to sort materials. Near-infrared technology is an electromagnetic wavelength of between 780 – 2526nm.

These infrared rays absorbed by the material’s molecules produce a light absorption spectrum that is different from in every material. This makes it easy for materials to be identified and sorted depending on set parameters.

NIR graphic is mostly used to sort materials depending on the materials’ chemical composition regardless of the shape and size of materials such as plastic.

X-ray Graphic technology

Invisible x-rays penetrate the materials. The rays are reflected and converted to electric signals and later image signals.

X-ray graphic Technology is mostly used to detect foreign materials. The density of the material plays a key role in the accuracy of x-ray Graphic technology.

Optical Sorting Technology In Color Sorter

In this part, I will introduce more details about the optical sorting technology combined with the color sorter.

Step 1: Products Enters The Optical Sorting Machine

The materials to be sorted are feed into the optical sorting machine through a feeding hooper in their mixed state.

Step 2: Materials Passes Through The Vibratory Feeder

The vibratory feeder controls the entry of the materials into the chute to avoid overcrowding or overlapping of products.

Step 3: Materials are Accelerated and Singulated

The vibratory feeder controls the flow of products into the chute. This is where they are accelerated so that they can be singular for easier viewing. In most cases, the chute is slightly inclined to achieve acceleration.

Step 4: Products Viewing and Classification

The viewing areas have lights, sensors, and cameras to view the products and classify them according to color and set parameters.

The classification is done mid-air where the ejector pushes the products that do not meet the parameters to the reject bin through compressed air.

Step 5: Materials are Accepted Or Rejected

If the material does not meet the set parameter, it is pushed off the path using pressurized air.

The final results will be an accurate separation of the products with the acceptable and rejected products in their place.


Color sorting technology is useful in offering accurate sorting, separation, grading, and categorization of various materials and products across several industries. This comes with an advantage such as reduced labor cost, high-quality production, and high return on investment.

Edon Zheng

Edon Zheng

Hi, I'm Edon, the co-founder of, I've been running a factory in China that makes and exports color sorters for 8 years now, and the purpose of this site is to share with you the knowledge related to color sorters from a Chinese supplier's perspective.

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