Sodium silicate or caustic can assist in dispersion of the clay.Issue to consider:

• Amount of clay present. The use of 2 stages of scrubbing followed by classification can be useful if the clay content is very large.

Do you have any data about the water chemistry? Softening the water will help with dispersion. Another dispersant to consider using would be a poly acrylate acid.

Would you be able to advise us on the clay content, clay type or if any experiments had been run?

It is a surface coating and goes easily by washing and fired color improves in ceramic after this washing. My intention is to accelerate this washing process and remove clay completely for increasing fired whiteness.

Let me do some test in couple of days and will update.

I agree with the comments above that its very clay dependent. Here is another idea.

A few weeks ago I got to visit a potash plant and they handled their clay problem in a very different way to what I had seen before. In their rotary conditioner prior to the float (basically a rotary scrubber) they put in an additive to agglomerate the clay. The feed to the conditioner was approximately 2-4mm. The challenge was then to remove the agglomerated product; in this case it didn't float so it worked well.

That was a novel approach at the potash plant. Can you comment on process selection for removal of the agglomerated product?

What is the additive which makes clay to agglomerate and ours also rotary scrubber.

The agglomerated clay is significantly larger than the individual particles hence doesn't report to the float conc. and is thus rejected. In this particular case I'm not sure how this would work perhaps if there is a size differential with the feldspar you could screen off after the scrubber? At least if it is agglomerated it shouldn't stick to the feldspar particles....

Sorry I can't comment on what chemical is used for the agglomeration but I'm sure if you talk with the chemical vendors they may be able to help you.

Have you considered an Attrition Scrubber? It liberates clay particles. No chemicals needed. Have a look at Metso Minerals website. (i.e. http://www.metso.com)