Urban Mining – Steel Scraps

While I intuitively like the concept of Urban Mining - we have all these precious raw materials within easy reach of robots - I know nothing about it. I want to remedy that with the best ignorance cure of all: YouTube! Please, see an exteneded list of videos at the bottom of this post.

The rest of the post will focus on steel recycling to understand the problems and potentials (with regards to AI and robotics) in this industry.

ELB in Duisburg:

Hammel metal separation:


The steel scraps produced in the recycling videos go to steel plants. To see how important this raw material is, check out Thyssen-Krupp's product website.

Important problems

Here is a list of problems that are specific to steel recycling -- as shown in the videos from ELG.


Perhaps the elephant in the room is that recycling can be a very toxic process. This gives an edge to countries with more relaxed regulation, e.g. certain Asian countries. For example, to extract gold from electronics you may use cyanide. If robotics are more pervasive in robotics, this could eliminate the edge of low-regulation countries as recycling can be done in pure machine environments.


The scrap buyer at the German company (ELG in Duisburg) must buy deliveries of scrap metal on a daily basis and at the right price. For example, nickel can be particularly expensive. She will sometimes go out of the office to buy even small quantities of steel from scrap dealers, and always carry a magnet in her pocket to test the quality.

The dealer has to sell her the steel at a loss because he is running low on space! However, since many competitors also wants to buy the scraps, the buyer has to offer fair prices and have the dealers interest in mind.


The scrap company must examine the quality of a shipment (e.g. steel) before it can be sent to a plant. The process involves cutting out samples, melting the samples and finally determining the alloying elements (e.g. molybdenum) it contains. High-grade steel must have the right mix of non-iron elements. Furthermore, the scrap should not contain toxis elements, such as heavy metals.


A shipment of steel scraps may contain copper or zink parts. These metals would contaminate the steel melt later on, so they have to be picked out of the pile before shipping to the steel plant. Workers at a German plant manually sort through the pile and test the metal with a magnet!


Big pieces of scrap larger than 500 kg have to be cut into smaller pieces, otherwise they won't fit in the furnace of the customer. ELG uses a big crane fitted with a giant claw to cut big pieces of sheet metal (e.g. from dismantled factories) into smaller pieces.

Sometimes ELG uses external companies to reduce the piece size for them.


Another problem that is exposed in the video is that of transportation. A delayed shipment of scrap metal to a steel plant can cause critical downstream delays in the supply chain. In the video, the recycling plant receives too few rail cars into their on-sight train yard (how cool is that!). They have to act fast in order to get the shipment out the door, which means they have to get more train cars fast. Perhaps an alternative would be to ship the metal using self-driving train cars that can be summoned on demand or some other sci-fi solution.

Making new steel

The scrap is melted into new steel in an electric arc furnace at the plant. The furnace uses a lot of electricity! At the plant, the composition of the scraps is analysed again using a randomly selected sample of the shipment. The balance of chromium, nickel and phosphorus to iron has to be within certain bounds.

Robotic potential

How could robots solve the problems outlined above?

Additional video material that relates to Urban Mining

Some of these videos are about extracting gold from electronics.



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