On the afternoon of Wednesday 22nd March, the lot of us arrived at Degussa in Miles Platting, NE Manchester (minus Graham, Chris, Tom, Mike, and Miss Rodgers – they were at the science museum – skiving!)
For the second time, Mr. Wood actually got there first! First of all we got posh name tags , disposable jackets and lovely blue helmets and goggles. We were split into two groups and while one had a briefing of history of the site, the other went to meet Mr. Pattel (remembered for his coughing and time checking "We have 5 minutes!"). Afterwards we swapped around. One useful fact he told us was that 60-80 % of the pigment made is used in printing inks. He also insisted that blue was either red or green, (yeah right!)
After that, we made our way out to the plant, where we discovered blue people (not Smurfs), and a black and blue cat.
We watched a demonstration of how Prussian blue was made, and saw where all of the chemicals were mixed to make large amounts.
Basically, the process going on was taking Iron II ions from wire cleaning processes in a mixture of HCL. The H+ ions were neutralized by OH– ions and the Iron ions were then reacted with NaCN to form "Yellow prussipite of soda" Known as YPS=Sodiumhexacyanoferrate 2 (Na4Fe(CN6)). The YPS was then reacted to displace the Na and replace it with more Iron to form "Prussian White" which was actually Iron2 hexacyanoferrate2 (Fe2Fe(CN6)). They then oxidize this "Prussian White" using Sodium Chlorate (NaClO3) to produce the Prussian blue.
The Prussian blue has various uses in the printing industry. Some examples of companies using this pigment are Walkers, Cosmopolitan, and various other packaging and magazine companies.
All in all, the entire tour was rounded off with a question asking session in a conference room. This turned into an economics discussion on the value of the pound and the euro. During all of this we were given coke/tango (warm) but it seemed to work.
Overall, the afternoon was very interesting and I think that it will be interesting to spot where the pigment is used from day to day.