NETZSCH’s Latest s-Jet Steam Jet Mill
Netzsch’s latest dry grinding machine uses superheated steam as the source of power to grind dry products down to the nano range, which could only be achieved via wet grinding in the past (conventional dry grinding processes could only reach fineness in the range 1~2 µm). The processes required the use of grinding media (e.g. yttrium-stabilized zirconia or zirconium silicon grinding beads), which collided with the walls of the grinding chamber and other grinding beads during the grinding process, resulting in high wear. The replacement of grinding beads and maintenance of grinding chamber thus caused an increase in costs.
In light of the two factors described above, Netzsch developed the revolutionary s-Jet grinding system. S-Jet is able to reduce the fineness of products to 100~200 nanometers (d50) in a powdered state because it uses steam as the milling gas.
Steam has lower viscosity and density than air, so the machine is still able to successfully grind the powder, even if it already reaches the micron or nano range.
Furthermore, this source of power has higher energy and can reach jet speeds of up to 1,200 m/s, which is roughly twice the speed of traditional jet mills at 550 m/s.
Kinetic impact energy of the particles inside the fluid bed rises fourfold. This is why s-Jet can achieve finer particles in a dry grinding process.
Besides grinding products into the nano range, s-Jet can replace traditional dry grinding mills. In the case of aluminum oxide, the production capacity of s-Jet can almost reach triple the amount of Netzsch CGS, greatly increasing production efficiency. Yet, s-Jet is able to maintain high quality production because of the ConVor separation system, a patented design of Netzsch. The special geometric design of the ConVor separation system allows powder to maintain the same speed when passing through the separation system. This prevents particles that are too large from being brought out of the system due to an increase in speed, and allows the narrow range of fineness shown below to be achieved.
