Rock Solid ziet reststoffen niet als een eindproduct, maar als een grondstof. Door ervaring in en kennis van chemische en civieltechnische aspecten en processen, maar ook door een open en innovatieve opstelling is Rock Solid in staat om uit reststoffen nieuwe grondstoffen te produceren.

In addition to having an extensive network within our field of expertise, we also guarantee high quality application/s of raw materials. This enables us to build up enduring relationships with the both the supplier/s of the residues and the user/s of the raw materials. Industrial areas where Rock Solid already supplies secondary raw materials include:

  • concrete industry
  • asphalt industry
  • cement industry
  • steel industry
  • non-ferrous industry
  • road and construction industry

If you are in search of high quality processing or affordable raw materials, then Rock Solid will help you to find the right solution.

Incinerator bottomash

The largest amount of residue after the incineration process is incinerator bottom ash. This is a mixture of materials whose upgrading can be divided into three distinct categories: metals, aggregates and non-incinerated materials. The metals and aggregates recovered are recycled and the non-incinerated materials are brought back to the waste-to-energy plant for reprocessing.

To optimise the separation of materials and to ensure high-quality aggregates, Rock Solid uses mobile upgrading/processing plants. The benefits of this are:

  • flexible operations
  • not tied to a single location
  • the possibility of combining ash from various installations
  • constant possibility of quality improvement.

The use of mobile plants makes it possible to upgrade smaller amounts of incinerator bottom ash to aggregates. This is done together with a partner contractor who has the capability to extract higher percentages of ferrous and non-ferrous metals, and thereby produce cleaner better quality aggregates. To further upgrade aggregates, Rock Solid has been developing new technologies which enable us to convert incinerator bottom ash into a freely available building material.


Rock Solid has long standing experience in the stabilisation and immobilisation of residues. This enables us to breathe new life into residues by recycling them into new raw materials. StabiRock is an immobilisation product, a concrete-like material, which is particularly suitable as a foundation material under paved surfaces, such as:

  • roads
  • park and ride areas
  • container terminals
  • depots
  • storage/transhipment premises

The technical properties of StabiRock can be adjusted to the specific demands of the foundation. By customising the foundation , considerable savings can be made on the overall construction costs.

Rock Solid not only offers a sustainable solution, but also an economically attractive alternative.


ICL Fertilizers Europe (ICL) and Rock Solid are collaborating to use nutrient-containing residues as raw materials in the production of fertiliser. Ash from biomass energy production (on the form of sewage sludge, poultry manure and wood) is potentially suitable as a raw material for fertiliser production. The expertise of both companies complement each other in this project.

Nutrients are essential for all life on earth. The demand for it has been growing rapidly as a result of an increasing world population. This is not just for food production purposes, but also for biomass production, which is playing an increasingly important role in energy supply. In the current situation, nutrient demand is mainly provided by primary materials. However, these materials are finite and if no alternative can be found, future generations may not be able to meet their basic food requirements.

Forecasts show that natural supplies of phosphates are only sufficient for the next 50 to 300 years. Residues of biomass energy production often contain high concentrations of primary nutrients. These residues are not currently utilised in the nutrient lifecycle, being either dumped or subjected to low-grade processing. With the new recycling technology used by ICL and Rock Solid, the material cycle can be closed and recycling taken to a new level.