Human History – The Incentive of Waste Recycling Remains the Same…Extracting Value

Entry by Dr Tim Johnson, Technical Director at Tetronics

So there we were, sitting at a pavement café in the romantic Italian city of Sorrento on the first day of our holiday when I took out my camera, pointed it at my wife and then started taking pictures of the wall behind her head. Obviously, she thought I had gone mad, but what had taken my interest (I admit, in a slightly sad and scientific way) were the large blocks of porous volcanic stone this wall was made up of.  In fact, a great many buildings in that part of Italy are also built from this tufo, including a fair few which are still standing proudly after 2000 years or more.  A visit to the top of Vesuvius later in the holiday revealed the ultimate source of this highly useful building material, although here most of the rock was quite different in character, being darker and fully dense.  In both cases, I was struck by the strong similarity in appearance between these volcanic materials and the Plasmarok™; traditionally known as ‘slag’ we commonly produce at Tetronics from our pilot plants and commercial plasma facilities.  On the other hand, this similarity comes as no great surprise since Plasmarok and lava are essentially the same thing, other than the one is man-made and the other is naturally occurring.

Almost all industrial processes generate by-products and in the case of high temperature processes like plasma a lot of these are a mixture of metal oxides in the form of a molten glass, what the industry used to call a ‘slag’.  At a recent conference on the treatment of steel industry wastes, speaker after speaker stood up to report not only on how they were recovering metals from their waste and returning them to the main production process, but also on how various slag was being transformed into useful products for road surfaces, cement fillers and other aggregates.  And indeed, such reuse of wastes has been a feature of the metals industry for literally thousands of years with a high proportion of today’s metallurgical waste being put to good use in one way or another.

For most of human history the incentive to recycle wastes has not been an environmental one, but rather an economic and/or practical one.  Many wastes were a valuable alternative to more traditional raw materials, plus there was the practical problem of disposing of a large mass of waste, year after year, in times where the costs and difficulties of transport were high.  We may live in a very different world today, but the economic and practical incentives remain as strong as always and there is now a greater encouragement to recycle and recover materials than ever before. The enormously widespread (but almost unnoticed) use of materials derived from what one might call natural ‘slags’ in everything from buildings to jewellery provide us all at Tetronics with a powerful encouragement to find ever more innovative ways to imitate nature through the development of new and exciting alternative uses for that much-underrated resource: yes, slag.

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