The diagrams below show the stages and equipment used in the cement-making process, and how cement is used to produce concrete for building purposes.

The first diagram illustrates the process of cement manufacture, and the second diagram shows the materials that go into the production of concrete.

It is clear that there are five stages in the production of cement, beginning with the input of raw materials and ending with bags of the finished product. To produce concrete, four different materials are mixed together.

At the first stage in the production of cement, limestone and clay are crushed to form a powder. This powder is then mixed before it passes into a rotating heater. After heating, the resulting mixture is ground, and cement is produced. Finally, the cement is packaged in large bags.

Cement is one of the four raw materials that are used in the production of concrete, along with gravel, sand and water. To be exact, concrete consists of 50% gravel, 25% sand, 15% cement and 10% water. All four materials are blended together in a rotating machine called a concrete mixer.

(160 words, band 9)

the cement-making process---cement manufacture

to produce concrete---production of concrete.

To write an introduction about a process diagram, just paraphrase the question statement as usual.

For the overview, here are some general things that you could mention:

- the number of stages in the process
- where / how the process begins and ends
- the items (e.g. materials) involved in the process

Let's return to the 'cement' task and write the introduction and overview.

Let's start with the 5 nouns that mark the 5 stages of this process:
crusher, mixer, heater, grinder, bags

We can convert these nouns into passive verb forms:

Limestone and clay are crushed.The resulting powder is mixed.It is heated.Then it is ground.The final product, cement, is bagged.

Or we can keep the original nouns, and use active or passive verbs:

Limestone and clay are placed in a crusher. (passive)The resulting powder goes into a mixer. (active)It then passes through a rotating heater. (active)The heated mixture is put into a grinder. (passive)The cement is packaged in large bags. (passive)

Of course, the best approach is to use a mix of the above options:

At the first stage in the production of cement, limestone and clay are crushed to form a powder. This powder is then mixed before it passes into a rotating heater. After heating, the resulting mixture is ground, and cement is produced, Finally, the cement is put in large bags.