Hi Anabel, I have read this closely. I have found a few things which you correct.
Firstly, I have read your overview. It doesn't matter if you wanna the overview in the last paragraph because there is not a rule about that. However, as we know that the overview is one of crucial points, I suggest you place it in the first paragraph after outcomes of paraphrasing the question/statement. Keep in your mind that you will fight the time if you should play safely. Besides that, your first paragraph has not described the good paragraph. You have to remember that you are supposed to write at least 3 sentences in the paragraph.
cement production is passing limestone and clay through
I suggest you deliver proper word to explain what you mind. I think you should write
"limestone and clay are blended in a crusher". If you fail in picking the proper words, you will miss getting the high score in both indicators (lexical resource and coherence and cohesion). Actually, there were a few words which can not illustrate what you mind well. Following this, please you avoid repetition. It can reduce your score as well.
You need making its flow smoother. Harnessing the transition word is the good way to guide readers to understanding your writing. I believe you can master this matter on condition that you wanna need more time for reading examples of writing task 1.
Practice more and more is its key.
GOOD LUCK