IELTS writing task 1

The two diagrams depict two different processes for the cement production and the concrete production.

The cement making process is composed essentially by of five different stages. To begin with, limestone and clay are poured into a crusher, which is used to obtain makes the powder. (You could use the passive "which is used to make", but we use it less than Italian does)
In the second and third stages the powder is introduced in a mixer and then is passed through a rotating heater, where the powder is heated. In the final two stages, the product coming from the heater is brought to a grinder, which provide to give provides / gives (choose one word or the other) the final product: the cement. Then, it is packed into bags to be carried easily where they need it it is needed. (Since we don't know who "they" are, we will have to use the passive here).

The second diagram illustrates the concrete production using the cement as a basic element. This process is completed in three different stages. In the first part, cement and water are put in a concrete mixer in particular percentages of 15% and 10% respectively.In the final stage the rotating action of the mixer will be enough to obtain the required product: the concrete. (I suspect that you have the articles at the end "the cement" and "the concrete" because Italian requires the article for the general product, but English does not.)

Good luck on the exam!