Blue nano tungsten oxide for thermal insulation dispersion may be prepared in a rotary kiln using ammonium paratungstate (APT) as a raw material.
In the process of reducing APT to prepare blue tungsten oxide, after the formation of blue tungsten oxide (WO2.9), the WO2.9 particles enter the discharge hopper from the furnace tube and slide into the discharge pipe along the inverted cone funnel. At the same time, the water vapor, N2, H2 and part of the fine powder coming out from the furnace tube are driven by the fan to enter the settling tank from the upper part of the hopper. The fine powder is collected in the settling tank. And the water vapor, N2 and H2 is vented to the atmosphere by adjusting the gas valve and passing through the fan.
Because the thread opened on the push screw has a certain distance from the outlet of the discharge hopper, and the feed end of the discharge pipe is lower than the discharge end, blue tungsten oxide particles entering the discharge pipe are stacked at the outlet of the discharge hopper, that is, at the feed end of the discharge pipe. The stack results in a better seal of the outlet of the hopper. After the stack is formed until the outlet of the hopper is closed, the blue tungsten oxide particles at the edge of the stack are in contact with the threads of the push screw. Thus, the particles at the edge of the stack will move toward the exit end of the discharge tube as the screw rotates. When passing through the discharge pipe, blue tungsten oxide particles are cooled by a layer of water chamber covered by the outside of the discharge pipe to achieve the purpose of cooling.
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