In the primary industry sector, functioning networks for using secondary raw materials are already in place. But to further close the cycle of materials and use raw materials in the most efficient way possible, new approaches for recovering and using secondary raw materials need developing.
Industrial symbiosis – example of integrated chemical parks
- Creates shorter transport routes by setting up the facilities needed to produce basic chemicals and manufactured chemical products. For example, chlor-alkali electrolysers need to be located at chemical facilities to avoid transporting the chlorine needed to produce polyvinyl chloride (PVC). In integrated chemical parks, operating gas, water and steam are made available centrally by a steam power plant supplying several companies via a pipeline network.
- Heat integration (i.e. using heat from cooling processes to provide heat for other processes) not only in-house but also between local companies via a heating grid.
Industrial symbiosis – example of the cement industry utilising waste from the steel industry
- Blast furnace slag, which arises as a non-metallic by-product of the steel industry and hence finds no application in this sector, is used as a raw material in the cement industry. The granulated slag it contains thus substitutes clinker, a carbon intensive by-product.
- The transformation of the steel sector with the transition to the DR-Verfahren (direct reduction process) and the expansion of steel recycling in electric furnaces results in the removal of blast furnace slag as a by-product. Potential ways of using electric furnace slag as a secondary raw material in the cement industry need further research.
Utilising secondary products – example from the chemical industry
When producing the base chemical chlorine using chlor-alkali electrolysis, sodium hydroxide (caustic soda) is accrued as a by-product and new processes have been developed to make use of this substance. Nowadays, sodium hydroxide is used in the chemical industry as a neutralising agent and in the production of aluminium and glass. Sodium hydroxide is also implemental in processing chlorine into polyurethanes and polyesters.