The nano-diamond powder is obtained by crushing and grading coarse-grained single crystal diamond. Using a ball mill to grind the diamond to produce diamond powder is the most commonly used method. The ball mill crushing method has been used in the production of diamond powder in my country for many years and has achieved satisfactory result. However, due toshortcomings of the low production efficiency, it has been replaced by jet mills. Jet mills use compressed air as the working medium. The compressed air is sprayed into the crushing chamber at high speed through special supersonic nozzles. The airflow carries materials at high rates. Make intense collision, friction and shear between materials and materials to achieve the purpose of crushing. The most significant advantage of the jet mill is that it is not limited by the mechanical linear velocity and can produce high air velocity, especially the supersonic jet mill can create a flow rate several times the speed of sound so that it can generate substantial kinetic energy. It is easier to obtain micron level And sub-micron ultrafine powder. From the principle of pulverization, this type of machine is more promising for the production of diamond powder.
Grading is a critical process in the diamond powder production process. It involves the production efficiency and quality of the diamond powder. At present, the most widely used in diamond powder particle size classification method in China is the combination of natural sedimentation and centrifugal processes to produce a fine powder.
The natural sedimentation method is a sorting method that directly applies to Stokes's law. According to the principle that particle of the same specific gravity have different sedimentation speed in water due to different particle sizes, the particle size can be classified by controlling the sedimentation height and sedimentation time. Simple, easy to operate, stable quality, but long production cycle and low labour efficiency. To this end, many domestic and foreign manufacturers have developed automated grading equipment, using the computer technology and frequency conversion control technology, equipped with four systems of automatic mixing, automatic pumping, automatic water circulation and computer control. All digital design, precise control, energy is saving Electricity, with high efficiency, high reliability and good maneuverability unmatched by humans. Compared with manual sorting efficiency, it can be increased by 10-20 times. It has the high degree of automation, fast sorting speed, accurate sorting accuracy, no impurity pollution, unmanned factor interference, robust product quality stability, good reproducibility, and labour intensity. Ten significant advantages of small size, the low labour cost of enterprises, and a large amount of one-time feeding.