IELTS writing task 1 a real process description

IELTS Writing Task 1: a real process description
You might find it useful to read a real process description from this website about
insulation manufacturing. The extract below looks very similar to a paragraph from an
IELTS essay!
For glass wool, the raw materials are sand, limestone and soda ash, as well as recycled
off-cuts from the production process. The raw materials are melted in a furnace at very
high temperatures, typically between 1,300°C to 1,500°C. The smoke created during this
process is filtered and flue gases are cleaned to minimise any environmental impact. The
droplets of melt exiting the furnace are spun into fibres. Small quantities of binding
agents are added to the fibres. The mineral wool is then hardened in a curing oven at
around 200°C. The mineral wool is cut to the required size and shape.
Task:
Can you find the passive verbs in the paragraph above? Can you improve the paragraph
by adding some sequencing words (firstly, then etc.)?