If you are adequately controlling the kiln feed residues to 15 per cent I am not sure what the grit return weigher is going to tell you. Will you be able to remotely adjust the vanes of the mechanical separator from the control room while the mill is running? If not I would suggest periodic sampling and measuring residues around the circuit is all you need to do to determine the rejects rate. What do you mean by "optimise" the raw mills? Do you need more raw mix output? Is there sufficient drying capacity in the mills? I presume they are swept by preheater exhaust gases?

We have a VSK unit with 300tpd production. The raw mix contains limestone, clay, cokebreeze. We are getting continuously high free lime. Please advice the procedure through which we can reduce the free lime.

There are a number of reasons why you might be getting continuously high free lime in your clinker. The most likely ones are: (i) there is too much limestone in your raw mix, (ii) the raw mix is not ground to sufficient fineness, or (iii) the temperature in the kiln is not high enough to finally combine the free lime with the clay minerals. The problem might be a combination of all these factors.

We have started using a new raw material as a silica source. This material contains a significant amount of titanium. Coincidentally, our free lime content has increased. Can the material be the cause? How stable is perovskite (CaTiO₃) as a clinker mineral?