PRECHEZA a.s. published a book on FEPREN iron oxides.
30. 8. 2020

PRECHEZA a.s. published a book on FEPREN iron oxides.

See what the author says about of the new book.

I came to the factory almost straight out of university (at the time, it was not called Precheza yet but it was no longer Mutual Agricultural Factory for Fertilizers and Chemicals either). I was educated in general chemical theory but lacked thorough practical knowledge. Therefore, when I came to Přerov Chemical Factory, I had to learn the specifics of the products manufactured there. Titanium dioxide production is the company’s main product today, whereas iron oxide pigments are a complementary product, back then, the company primarily produced fertilizers and iron oxides were rather a marginal part of its portfolio. However, this was not the case when it came down to research, and iron oxide research group became my workplace for many years.

Although the company’s manufacturing program was focused on fertilizers, both titanium dioxide and iron oxide pigments had their own brochures describing their properties and production technology, pigment evaluation methods and application areas. A rookie in the research team usually received a black-and-white or a black-and-red brochure, or both, and was told to go and read “something about pigments”. Both brochures were created around the same time when titanium dioxide and iron oxide pigment manufacturing rollout, i.e. in the early seventies. Obviously, information presented in the brochures gradually became obsolete, even though iron oxide red was and remains hematite and anatase and rutile are still the two structures used in titanium dioxide production. In any case, approximately 7 years ago, Milan Laskafeld and Petr Stolín from the technical service team decided to update the titanium dioxide brochure, add new evaluation methodology, add and expand application areas and publish a new brochure. This is how Titanium Dioxide, the new book, came out in 2014 in both Czech and English. Then, for a few years, nothing happened.

At the end of 2018, somebody came up with the idea to publish a new version of the book on iron oxide pigments but they believed that it would be a lot of work, too much work to complete it successfully by 2020, there would be nobody willing to do it etc. But because I had just completed a summary of manufacturing methods and properties of inorganic pigments for Pardubice University, I convinced my colleagues that we could take on the challenge. I didn’t quite have an idea yet how much work writing a book would be. One of the first questions was to what degree we could use Ctrl-C and Ctrl-V. Pigment evaluation methodology is one of the things which are not much different, whether it is a white, a red, a green or a purple pigment. Although we tried to avoid simple copy-pasting the chapters included in the previous book which dealt with titanium dioxide, it could not be avoided completely, both in evaluation methodology and in applications.

Of course, titanium dioxide is white and can be anatase or rutile, and iron oxide pigments are red, yellow or black, in other words, coloured. They are even called that, colour pigments, and when we included chromium green, ultramarine and mixed oxide pigments, things became even more colourful. Finally, working on the book was fun, especially looking for information on technology and history of production and use of colour pigments. For example, I discovered that the first patent on manufacturing iron oxide reds using calcining was registered by John Atkinson from Harrington back in 1794. This was an industrial process; iron oxide pigments came into use way before that.

Unlike titanium dioxide, which was developed approximately 100 years ago, iron oxide pigments had been used for many thousands of years. Even the cave paintings dating back to 40 thousand years ago where, to a large extent, created with iron oxide pigments (although, of course, they were not a product of industrial manufacturing at the time). We could also explain in more detail what is colour, why a red is red, what makes a yellow yellow and why black is black. We also explained why mixing colour pigments together would never produce black, just gray. As for pigment properties evaluation, methodology was more or less the same as in the previous book but we found some methods and properties which were typical for colour pigments specifically, either because they are coloured or because they are also used in construction. By cutting into some chapters and referring the reader for more details in Titanium Dioxide book, we could spend more time describing in detail how particle size is measured; this area is linked to many errors and lack of knowledge even among experts. Various methods can be used for measuring particle size and each of them will produce the right result for the given sample but individual results may differ significantly.

Construction materials are the main application area for iron oxide pigments. The reason is their durability, lightfastness and stability in mixtures with strong alkaline construction materials such as concrete. Iron oxide pigments can be used in the majority of other segments such as coatings and plastics. However, unlike titanium dioxide, yellow and black pigments are sensitive to heating, which limits their use in plastics.

It makes no sense to try and squeeze all information which you can find in FEPREN – Iron Oxide Pigments book in this article; it would not even be possible. This is why I prefer to leave you with a few intriguing questions, answers to which you can easily find in the book (or elsewhere):

1. Natural iron oxide pigments (ochres) are also known as umbra or sienna. Do you know why?

2. Sunset and sunrise on Earth are red. Why? What is the colour of sunset on Mars?

3. Yellow iron oxide constitutes tiny needs of a mineral known as goethite (chemical formula FeOOH). The mineral known as lepidocrocite has the same composition. How are these two minerals different?

4. Under certain preconditions, specific surface can be used to determine the average particle size. How do you do that?

5. What (besides pigment colour) determines the final hue of coloured concrete products?


Finally, I would like to thank everyone who contributed to the book – those who wrote individual chapters, who reviewed them, and, first and foremost, to my colleague Jitka Koppová, without whose editorial work this book would hardly be a success.

Petr Pikal

Head of Research and Development

PRECHEZA a.s. Přerov