Tungsten Carbide Mixture Wet Milling-spray Drying (2/2)

In the process of preparation, it is significant that choosing the granularity and controlling the balance of carbon and oxygen. It requires uniform WC powder and the original granularity is equal to tungsten carbide granularity after sintering. The balance of carbon and oxygen is not only the most critical but also the most difficult to control. Due to the fluctuation range of the content of W-C-Co ternary alloy allowed in C is extremely limited, the decarbonized phase (η phase) and carburizing phase (graphite phase) will have a great impact on tungsten carbide performance.

Next, wet milling adds WC powder, Co powder and additives or carbides prepared into the grinder for milling until the ground to the desired particle size and thoroughly mixed with the Co. In the wet milling process, only the destruction of the dispersed particles and aggregates, crushing and dispersing the material fully, in order to ensure effective mixing between each component powder. And wet milling will be specifically divided into rolling milling and stirring milling. Roll milling uses the grinding ball and grinding media (the mixture) rotated to a certain height in the friction and centrifugal force to fall freely on the tube material will have an impact and grinding effect of grinding material and stir well. While stir milling depends on the power drive shaft rotatable stirring and stirring ball material, cut its rotation and centrifugal force generated by the component material and the ball moves in radial. Due to the end of the tube and the tube wall resistance and resistance in the material sphere generate vertical component and tangential component and material spiraling ball, colliding with each other, forming a complex friction movement.

Spray-drying tower is a kind of advanced process in tungsten carbide mixture drying and granulation. After the mixture after the wet grinding with pumped into the feed tank, stir heating, pressure slurry is fed to the atomizer atomized into the tower from the bottom of the tower. After oil and gas heat exchanger heated nitrogen N2 gas from the blower to the top of the tower distributor and uniformly into the tower of the atomized slurry was dry granulated. Pellets after drying off the bottom of the tower back for recycling. Finally, after separated with fine grain preliminarily, washed and heated, the gas can be reused.

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