Do you really Know the X-ray Sorting Technology?

About X-ray

Since the 21st century, our lives have become convenient by the rapid development of science and technology. The application of X-rays has also changed every aspect of life. Especially in the coal preparation and beneficiation industries, the application of X-ray separation technology has overturned the traditional beneficiation methods.

X-ray (X-Ray), also known as Roentgen ray, was discovered in 1895 by the German physicist W.K. Roentgen. It is a stream of particles produced by the transition of electrons in atoms between two energy levels with very different energies. It is an electromagnetic wave with very short wavelength and high energy. Its wavelength (0.001~10nm) is between ultraviolet and gamma rays.

Features of X-ray

First of all, because X-ray is also an electromagnetic wave, it can show wave-particle duality feature, and can make the film photosensitive like visible light. In addition, it also has some other properties, such as penetration, ionization, fluorescence, heat, etc. These properties of X-ray make people apply it to various fields.

X-ray and mineral sorting

Sorting is a relatively common method for separating solid materials, and it has a long history of being used in mineral sorting. After the second industrial revolution, especially during a period when nuclear physics research has developed to a considerable level, the combination of sorting and the application of high-energy rays (such as lasers, X-rays and y-rays) and electronic computer technology has resulted in the research direction of radiation mineral sorting. And the selection methods using rays as the identification tool has truly risen from a traditional empirical method to a technical science.

Principle of X-ray sorting

The XRT sorter uses X-ray to scan the raw ore, collects data from the detector, and distinguishes the ore and waste rock through intelligent algorithm, and blow the waste rock away with the High-pressure blowers.

Main methods and application conditions of X-ray sorting

The signal recorded by the X-ray sorting method is the content of the selected element or element group in the ore, so the sorting process is not affected by other properties of the ore. X-ray beneficiation methods can be divided into three categories: X-ray-fluorescence sorting method; X-ray-absorption sorting method; X-ray-fluorescence radiation sorting method.

The X-ray-fluorescence sorting method is based on the characteristics of minerals that emit photons (visible fluorescence) when they are excited by X-rays to achieve mineral separation.

X-ray absorption separation method is to separate different minerals or rocks by different X-ray absorption coefficient of a certain wavelength and energy.

X-ray radiation sorting method is a method of sorting ores by using characteristic spectral lines generated by excitation after receiving X-ray irradiation.

Of course, three conditions are required when using X-ray sorting: the unevenly mineralization of the ore deposit, and the grades of the mined ore pieces are obviously different; the ore has a certain degree of lumpiness and must be granular or massive to facilitate the mechanical device Separation; the ore has separation characteristics that accord with the principle of X-ray radiation separation.

Factors affecting X-ray

1. The distribution of ore particle size. Appropriate mineral particle size distribution can greatly improve the efficiency of ore sorting. Different types of sorters have different upper processing limits of particle size, and the sorting effect of different ore sizes in the same sorter will also be different.

2. The speed of the belt conveyor. The speed of the feeding belt is an adjustable parameter of the equipment. It determines the amount of ore passing through the sorting area per unit time, which in turn affects the sorting efficiency of the ore. If the belt speed is too slow, it will reduce the processing capacity of the ore; if it’s fast, the amount of ore passing through the sorting area per unit time will increase the load of the sorting actuator, thereby reducing the sorting accuracy.

3. The ore sorting execution system. Nowadays, many X-ray sorting machines use high-frequency nozzles to sort ores by spraying high-pressure air. The power of the jet directly determines the trajectory of the ore. If the power of jet is too small, no matter whether it meets the sorting standard or not, the movement path change of the ore block will not obviously, making the sorting invalid; if it is too large, it will also affect the neighboring trajectory that meets the sorting standard, and makes the sorting invalid too.

4. Setting of the Identify threshold value. During X-ray irradiation recognition, the adjustment of its recognition threshold will directly affect the sorting efficiency of the machine. If the threshold value is too high, the amount of gangue will increase and the sorting recovery rate will decrease. If the threshold value is too low, the grade of the sorted ore will not meet the requirements, which will increase the load of the subsequent process.

Conclusion

X-ray sorting technology has been developed for more than half a century. Since we used the natural radioactivity of minerals to sort uranium-containing ores, to sorting by various rays in the spectrum range, the types of ore sorted and the industrial fields of application have become more and more extensive, including non-ferrous metals, rare and precious metals, Most industrial raw materials including ferrous metals and some non-metals.

Nowadays, many countries attach great importance to the efficient development and utilization of mineral resources and vigorously advocate the implementation of energy saving, emission reduction, consumption reduction and intelligentization of metallurgical mines. X-ray sorting technology, as a high-efficiency, low-consumption, and environmentally friendly method of beneficiation technology, is gradually gaining the attention and favor of domestic metallurgical mines, energy and chemical enterprises and related research institutes. At present, the application of X-ray radiation sorting technology and supporting equipment is quite mature, and the development prospects of X-ray sorting technology and application will also be bright.

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