Raw Materials and Quarrying Questions and Answers

Answer: C

Five per cent of 3,000 tonnes is 150 tonnes a day, and over 300 days that is 45,000 tonnes. A seemingly small substitution rate translates into a very substantial saving across a year. Substitution rates are quoted per tonne but judged on the annual total.

Answer: D

It governs the balance between the aluminate and ferrite phases in the clinker and affects how the melt behaves in the burning zone. Together with the lime saturation factor and silica modulus it fixes the character of the mix.

Answer: A

The first two describe normal practice. The third is wrong, since the factor is calculated from the oxide analysis rather than measured, which is why a fast and accurate analysis matters so much to the control of the mix.

Answer: B

Correct answer: True

The lime saturation factor is computed from the chemical analysis - the calcium oxide present as a proportion of what the silica, alumina and iron oxide could theoretically combine with. No instrument measures it directly. It is one of three such calculated moduli, with the silica ratio and the alumina ratio, and together they are what the raw mix is actually controlled to.

Answer: C

A cross-belt sampler takes increments as the material passes, giving a composite that represents the whole stream. Occasional grab samples would miss exactly the short-term variation that the control system exists to correct.