This Sankey diagram of energy flows in a “pusher type reheating furnace” illustrates an article on ‘Reheating Furnaces in Steel Plants’ by Satyendra on the ISPAT Guru blog.

Unit of flow is not clear, but the main stream arriving from the top represents the baseline 100% (508 units) of which a portion can be recuperated and fed back into the furnace as preheated air.

Browsing through the blogs on data visualization and infographics (check my blogroll) I often find inspiration in Nels’ MFA diagrams. From time to time I like to beef up the skinny MFA diagram skeletons a bit by converting them into Sankey diagrams. At the same time, by translating the numbers into Sankey arrows one gets a better idea what the main (mass) flows are.

This is a MFA diagram on Iron and Steel Flows in the European Union in 2000 as found in this post. Original data is from a 2008 OECD study, flows in Mt.

The description of the diagram says: “A study of iron and steel flows in 2000 in the European Union showed that an input of about 120 Mt of iron ore (of which 98 Mt was imported) yielded 98 Mt of primary crude steel (i.e. produced directly from iron ore and coke). A further 65 Mt, representing 40% of total crude steel production, were produced as secondary crude steel, produced from scrap steel.”

I did a first quick version of the flows as Sankey diagram, trying to stick very much to the layout of the original diagram. All nodes are the same size and more or less located at the position of the master. It already shows that the main steel flows: iron ore imported into the European Union, and steel scrap being recycled within the EU. Export of semi-finished steel products from the EU to the Rest of World (52 Mt) almost balanced with 47 Mt of semi-finished steel products imported into the EU.

I tried to improve the diagram by removing the three nodes ‘New Scrap’, ‘Prompt Scrap’ and ‘End of Life products’ since there is no transformation of these flows at the nodes (also no change in quantity). Further I reduced the size of some boxes and dragged the ‘Semi-finished Products’ (Rest of World) box closer to the ‘Finished Steel Products’ (European Union) box to avoid crossing streams. Wherever possible I try to avoid diagonal arrows.

The final result also has the Rest of World and European Union grouping. I am not to happy with the colors though.

Your thoughts?

Following up to my Aug 25, 2011 post on Global Steel and Aluminium Flows, I would like to recommend the follwing book that has just been released: Sustainable Materials – with Both Eyes Open: Future Buildings, Vehicles, Products and Equipment – Made Efficiently and Made with Less New Material by Julian M. Allwood and Jonathan M. Cullen.

I’m hardly a hundred pages into reading, but I already love it. The book is very graphical (to say the least), well illustrated, with many graphs and photos, infographics and even historic images. Plus – and this is why it deserves to be presented here on the blog – it features a great number of Sankey diagrams.

I really enjoy the lego bricks in the steel making flow chart (pp. 121-127). You’re also going to love the ‘WhatsApp’-style chat between Henry Ford and the Wright Brothers (p. 181).

This book “faces up to the impacts of making materials in the 21st century. We’re already making materials well, but demand keeps growing and so we need to start using them well to.” (from the back cover)

Sustainable Materials with Open Eyes by Julian M. Allwood and Jonathan M. Cullen can obtained from Amazon and – I am pretty much sure – from your local book dealer. Here is the book’s website.

You might remember the radial Sankey diagrams “invented” by Visio guy (here). This 3-D version below left me speechless… I hope the guys at junkcharts dedicate a critical evaluation to it….


(view the original diagram here)

This is from EUROFER (The European Confederation of of Iron and Steel Industries) and shows steel flows in fifteen European countries (EUR-15) in million metric tons. Values are for 2004. The grey area is supposed to represent steel accumulated in capital goods (machinery, buildings, …) over a certain life time.

Whooo woah, that’s a merry go round, I feel dizzy already!

Checking further on the authorship of the Sankey diagram I presented in this post, I came to the LCMP website at the University of Cambridge. LCMP? Yes … Low Carbon and Metals Processing. The engineering research group around Julian Allwood and Jonathan Cullen have three large research themes: WellFormed, WellMet2050, and WellMade.

The below Sankey diagrams are from the report ‘Going on a metal diet’ by Allwood, Cullen et.al. published within the WellMet2050 research theme.

The first Sankey diagram shows the global steel flows in 2007

the other the global aluminium flows in 2007:

One page 7 of the report the authors explain

“In our maps, the width of each line is proportional to the mass flow of metal. Values for the major flows are given in Mt (million tonnes). Steel flows less than 1 Mt and aluminium flows less than 0.05 Mt are not shown. Each major process step is shown as a vertical black line, with three possible outputs: useful metal (colored), process scrap (grey) and metal losses (black). Useful metal continues to flow to the next process step, while scrap loops back to the appropriate melting stage where it is recycled. Internal recycling loops, for example from the continuous casting processes for steel are shown small oval loops. (…)The working papers … give more detail about creating the Sankey diagrams

Unfortunately these two mentioned working papers are not (yet?) available on the website. These really fantastic Sankey diagrams have been compiled from different data sources. I thought I’d share them with you. Please visit the LCMP website and read about their other exciting projects.

This 1996 article on Energy Conservation Management (source: Charles M. Gottschalk: Industrial Energy Conservation, UNESCO Energy Engineering Series, John Wiley & Sons Ltd., Chichester, West Sussex, UK, 1996) has a Sankey diagram of the energy flow in a boiler system (will post that one separately one day, maybe). It also features the following steel factory material flow chart (flows are in MT per month, although the text says it is in tons/month):

I took this and converted it to a Sankey diagram, to better comprehend where the real material flows are, and where the biggest losses occur. Losses are distinguished from the other material flows with a
darker blue color. I actually produced two different versions: the first one sticks very closely to the original layout of the processes, the second one has more of a top-down flow direction.

I was unable to hook the flows to the corner of a process node as it is done in the original diagram (e.g. flow from cold mill to slitter line), Also, the little “bridges” where the arrow from circling to annealer crosses the three other arrows, cannot be reproduced in the same way with the tool I am using.

In the second version I need more space, but I think it is much more comprehensible as it sticks to a top-down flow direction. Losses branch off sideways. I added arrow heads for very thin arrows, otherwise they would sometimes be hardly visible. I refrained from putting the units behind each value to keep it like in the original.

Seems as if I have to much spare time, but this ain’t true…