In 1967, Yili Company of the United States successfully developed Yili's vibrating fine screen on the basis of curved screen, and applied it to the company's plant for the first time. In the past 20 years, the fine screen technology has developed rapidly, and dozens of new types have emerged at home and abroad. Fine sieving, which is widely used to improve the grade of iron concentrate, is mainly: Yili smashing fine screen, China's smashing nylon fine screen and high frequency fine screen.
In order to have a clear understanding of the fine-grain screening equipment , some of its characteristics are described as follows:
(1) The application of the principle of “large mesh sieve small particle material”. Most screening systems for fine-grain screening use this screening principle. Figure 1 shows the relationship between the mesh width and the separation particle size of a curved screen (including a vibrating fine screen, etc.).

As can be seen from Fig. 1, when the mesh width is 1.0 mm, the separation particle size is 0.5 mm, that is, the separation particle size is half the mesh width, which is a general case. However, when the mesh width is less than 1.0 mm, the separation particle size is less than half of the mesh width. When the mesh width is greater than 1.0 mm, the separation particle size is greater than half the mesh width. That is, the separation particle size varies with the mesh width. The smaller the mesh width, the finer the separation particle size becomes. These are the valuable features of the curved sieve and the like as a fine particle screening and classification device .

(2) There are more and more ways to prevent the screen from being blocked. Different fine screening devices have different mechanisms for preventing screen plugging. For example, Yili slams the mechanical splicing mechanism of the fine screen and the pneumatic piston mechanism. The German MS fine screen utilizes an unbalanced vibration motor for magnetic vibration. The British CTS screen utilizes the ribs on the back of the screen to break the flow layer in the screen hole to prevent the screen hole from clogging (see Figure 2). The Swedish Sarah cylinder screen uses flushing water. Germany Hamburg I type 2000 screening machine, using the irregular vibration of the camshaft. Lin Dalek screen using high-speed motor, and the screen vertical elliptical motion of the low-amplitude elastic .UR type sieve shaker and the use by the linear jet principle. The ultrasonic screening machine not only prevents clogging of the mesh holes, but also increases the screening efficiency when sieving fine particles. Most of these vibrating fine screens use high frequency and low amplitude vibration to avoid clogging of the screen holes. [next]
(3) The inclination angle of the sieve is large. The inclination of the fine sieving machine is larger than that of the conventional vibrating screen.
For example, Yili oscillating fine screen tilt angle 45 ° ~ 65 °. Hamburg I type 2000 sieve tilt angle 20 ° ~ 45 °. France VTHF type sieve tilt angle 30 ° ~ 40 °. Dai Beier ultrasonic sieve tilt angle 35 °. Huji sieve, The swirling fine sieve, the vertical cylindrical fine sieve and the V-type screening machine are all inclined at 90° (ie vertical screen). The inclination of the conventional vibrating screen is generally only 0°-20°.
(4) The screen material is constantly updated. Yili's vibrating fine screen is made of stainless steel wedge-shaped screen. The strip width is 1.6mm and the screen hole width is 0.089mm. The joint diamond mine belonging to Southwest Africa Co., Ltd. used high-speed steel mesh. The Alghero jet screen uses an elastic wire mesh. German companies to use the Harvard high wear-resistant, shock-resistant special steel wire mesh, high-quality steel, nickel, titanium, brass and other types of materials processing screen. Drake U.S. griddle to three-way, West Germany imported from alloy steel wire, using a sandwich structure, i.e. the screen surface by the two tensioned three-layer screen composed of the same, generally lower than the upper sieve mesh Small three screens.
Polyurethane screens developed and used in Germany and other countries generally have a life expectancy of 3 to 20 times that of alloy steel screens. The Soviet Union uses a polyurethane screen with a mesh opening of 0.5×25 mm, and each piece of 120×120 mm is used for vibrating fine screening. The effect is obvious and the life is extended many times. Australia's Abuminku Cleveland tin plant, using a 0.5mm mesh polyurethane screen on the DSM screen, has a three-fold life expectancy. According to Huji's test, the life of the polyurethane screen is 20 times longer than that of the alloy steel.
Germany produces a screen made of Trevila B-type monofilament. The newly invented polyester yarn has the advantages of corrosion resistance, high elasticity and abrasion resistance. It is smoother than the usual polyester screen. GKD Weaving screens made of synthetic materials, especially recently produced products such as polytetrafluoroethylene, polyphthalic acid and polyester, have been used. The use of synthetic compound materials instead of stainless steel for the manufacture of screens is still rapidly evolving. The nylon fine screen widely used in China is made of domestic nylon 1010 raw material, braided structure, injection molding fine screen, which has the advantages of wear resistance, low cost and easy to block the screen hole.
(5) The production and measurement techniques of fine mesh screens are constantly evolving. Due to new developments in screen materials, industrial screens with a mesh opening of 0.05 mm have been produced. The fine sieve used in foreign laboratories, the mesh size is at least 5μm or even 1-2μm, which is called electroforming microporous sieve.
With the development of fine mesh screen manufacturing technology, the measurement technology of mesh size has also been developed. The screening test of iron concentrate by Yili Company of the United States shows that the size of the mesh hole is decisive for improving the grade of iron concentrate. Therefore, it proposes to the manufacturer that the size and precision of the mesh hole is 89±13μm, that is, the mesh size. The range of variation is 76 to 102 μm. The company uses a special instrument for checking the mesh. It has been reported that the use of this instrument to measure the size of the mesh is 20 times faster than using an optical instrument that is magnified 100 times. According to recent reports, the use of optoelectronic scanning device, moving the sieve plate, can automatically measure the size of the mesh, the device measurement range is 0.02 ~ 1.25mm.

Vertical Mill Wear Parts

Hard-plate has many years experience to fabricate the nearly full set of vertical mill internal wear parts. The fabrications are mainly made from chromium carbide hardfacing plates, which has abrasion resistant property and could make the service life last longer than carbon steel.