Can I have the details about "patented TXI Cemstar addition of air cooled slag to cement kilns". Do you have any information of any cement plant using Blast furnace slag as raw material for rawmix. What are the basic requirements and the precaution we must take to use GBFS as a rawmix component. Will it affect productivity of the mill as I heard that slag is very difficult to grind.

The TXI Cemstar process involves the addition of air cooled slag to the inlet of the rotary kiln with the aim of boosting the output by up to 20 per cent. The distinction between "air cooled slag" and "granulated blast furnace slag" is important. I know of no factories using granulated slag as a raw mix addition while a number in the USA are using air cooled slag and the Cemstar process. This air cooled slag is not added to the raw mill, but added directly to the kiln inlet via a hopper and appropriate feeding device. This is the basis of the TXI patent from the Cemstar process.

Can we get the good quality clinker by using phosphogypsum as a raw material? Is any plant producing sulphuric acid and cement clinker as a by-product from waste phosphogypsum? If yes, kindly give the contact address of that plant1.

In Lea you can find reference to co-production of sulphuric acid and cement. Gypsum, clay, coke, iron oxide and sand are burnt together. The coke dissociates the gypsum producing lime and SO₂. The lime combines with theother materials to produce clinker and the SO₂ is captured to produce sulphuric acid. There would potentially be a problem with phosphogypsum due to the high P₂O₅ content of the resulting clinker. Sorry, I don't know of any plants using this technology.