The power drawn by the mill main motor is principally a function of the amount of media in the mill. Superimposed on that is some inverse variation due to the amount of material in the mill.

We are running a mini cement plant based on VSK technology in Africa and are having problems with initial strength. The plant produces Portland cement. The one day compressive strength is 10mpa using ENV 197-1 method. This increases to 17mpa after three days and becomes 28mpa in seven days. It reaches to about 42mpa in 28 days. The clinker is ground with gypsum. We would like to improve initial strength (ie strength of one to seven days) by at least 50 per cent. Can you please suggest any admixtures that can be included while grinding gypsum and clinker and what percentage will have to be added.

In order to boost the early strength you need to raise the lime saturation or silica modulus of the kiln feed and clinker. Unfortunately your VSK technology inhibits the possibilities to produce high early strength cement. You might approach Grace or Mapei and ask if any of their additives will solve your problem.

One alternative we have considered to increase the strength of our pozzolan cement is to add grinding aid (strength-enhancer).But during our first run, the blank sample exhibited more strength in the lab test compared to cement with grinding aid. Can the grinding aid will really boost strength to a greater degree? What grinding aids you can suggest for this purpose? Currently we have 28-day strength of 23 MPa but our objective is to reach 30MPa.