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Genanvendelse af brugt stenuld - Hovedprojekt

3 Summary and conclusions

Objective

The objective of the project is to investigate and assess the possibilities of setting up a recycling system for used insulation material made of stone wool. To support the objective investigations were carried out during the project at demolition sites. Furthermore the environmental and economical consequences of a recycling system were assessed.

Preliminary investigations of the future stone wool potential form the basis for this project. In the preliminary project the yearly potential of used stone wool for recycling were calculated to be 6,276 ton in 2003, rising to 14,375 ton in 2012.

Field investigations

The following field investigations were performed at demolition sites:

• Source sorting of used stone wool, and transport directly to a Rockwool production facility.
• Tests with use of used stone wool as raw material in the production of new stone wool products at the Rockwool production facility.

During the project a number of key stake holders working with demolition and recycling of construction wastes were interviewed.

Test results

Source sorting and treatment of the used stone wool have shown that it is possible to reach an almost complete separation of stone wool and glass wool. The sorting tests showed that an average of 90% of all stone wool taken out of constructions being renovated or demolished can be sorted to a satisfactorily quality and recycled.

Tests on production of new stone wool have shown that it is unproblematic to use used stone wool as a raw materials.  Fiberchemical analysis shows deviations between the used stone wool and the current briquette of raw material used for production of new stone wool products. It is however possible to adjust the fiberchemical composition of a briquette, so it is possible to add used stone wool in the production.

The tests have also shown that the current production capacity and production equipment can create problems with regards to obtaining the correct distribution between used stone wool and cement briquettes. This will especially be problematic if large amounts of used stone wool are to be handled and used in the production.

It will thus require investments from Rockwool to establish a recycling system of their used products. The investments needs especially to be used for production equipment and tools for controlling the received used stone wool.

Assessment of technical issues

The quality of the used stone wool sorted out during the sorting tests was of such a high quality, that it met the quality demands set by Rockwool. The stone wool could thus be used in the production with out a further treatment. If it is possible to obtain a corresponding quality in a recycling system, Rockwool will only need to invest in a control system for a new type of raw material, and will not need to invest in sorting equipment.

Source sorting of stone wool at demolition sites are assessed not to give difficulties in a recycling system. Widespread source sorting at construction and demolition sites are already common practice today, and are also be applied to stone wool.

Based on the production tests at the Rockwool production facility at Vamdrup the project has developed a list of specifications for the used stone wool that Rockwool is willing to receive and use in the production process. Specifications are made for the current conditions at the production facility (as they were during the tests) and for future conditions if Rockwool invests in new equipment.

It has been assessed that Rockwool needs to invest app. 5 million DKK in equipment and tools if used stone wool is to be included without problems in the production of new stone wool products. These investments will however make Rockwool able to receive up to 11,000 ton used stone wool per year (the current amount available for recycling is 5,609 ton/year in 2003) and the production system will thus be able to receive the future growing amounts of used stone wool.

Models for recycling of used stone wool

Three alternative models for recycling of used stone wool have been set up in the project. The models will be compared with the existing disposal system for stone wool to landfill; the exiting waste system is also called the reference system. The models for recycling are:

Model 1

• Recycling of used stone wool as raw material for new stone wool products at Rockwool (From west of Great Belt)
• Use of used stone wool as raw materials for production of sand blasting material at RGS90 (From east of Great Belt)

Model 2

• Recycling of used stone wool as raw material for new stone wool products at Rockwool (From west of Great Belt)
• Partly use of used stone wool as raw materials for production of sand blasting material at RGS90 (From east of Great Belt)
• Partly recycling of used stone wool as raw material for new stone wool products at Rockwool (From East of Great Belt)

Model 3

• Recycling of all used stone wool as raw material for new stone wool products at Rockwool (From west of Great Belt)

When setting up the models is was assumed that as much used stone wool as possible should be recycled. Thus it should be sorted and treated at the source (the demolition site) and delivered either directly to Rockwool or to another user, possibly via regional collection stations

A recycling percentage of app. 90% of the used stone wool potential is assumed in all models responding to 5,609 ton/year (2003). The remaining app. 10% will continue to be disposed at landfills.

Assessment of environment and working environment

The environmental consequences of establishing the 3 recycling models for used stone wool has been assessed, both external environment and working environment has been included.

The environmental screening of the models does not surprisingly show, that the environmental effects and the resource consumption are larger for the recycling models than in the reference system. This was also shown in the preliminary project, and is mainly caused by the larger amount of transport in the recycling systems compared to the reference system.

Naturally the amount of waste to landfills will on the contrary be reduces significantly in the recycling models compared to the reference system. Stone wool is a very stable type of waste, and it is thus modelled as volume waste in the impact modelling. Volume waste is mainly a problematic to landfill due to the fact that it takes up space in the landfill i.e. it is desirable to remove stone wool from the land fills to preserve landfilling space.

There will thus be both advantages and disadvantages in recycling used stone wool; a reduction of waste to landfilling, which reduces land areas confiscated for landfills and a larger consumption of non-renewable resources as well as more polluted air and water. It will be a clear advantage to recycle used stone wool compared to landfilling. This is also shown in extrapolated calculations for 2006 and 2008.

The procedures for sorting the used stone wool for recycling does not deviate significantly from the sorting procedures already performed at demolition sites. It is thus assessed that the source sorting of stone wool does not have a negative effect on the working environment.

Economical assessment

The following three costparameters are included in the economical assessment:

• Transport
• Containers
• Capital investments at Rockwool

The average costs for recycling of used stone wool in the three different recycling models as well as the average costs for disposal at landfills in the reference system is presented in the following table.

Model 3 and the reference system are the most expensive solutions for disposal of used stone wool, while model 1 is the cheapest. It should however be noted, that it is assumed that no extra costs are connected with source sorting in the recycling systems and that there are no necessary capital investments at RGS90.

The difference between the recycling systems have two main causes: Transport costs including crossing of the Great Belt Bridge, and capital investments at Rockwool.

The environmental and economical calculations in this project have been based on potential amounts of used stone wool generated in 2003. In order to assess future developments for the recycling models calculations have also been performed on potential stone wool amounts for 2006 and 2008.

Conclusions and recommendations

It will be realistic to obtain 90% recycling of used stone wool from renovation and demolition sites.

A recycling system for used stone wool can be established relatively simply and be economically advantageous, provided that the key stakeholders are willing to participate. A recycling system should be based on a geographical division between East and West Denmark and should have two different ways for recycling/further use, i.e. collection and delivery at Rockwool for recycling and use as raw material for Carbogrit at RGS90 in Stigsnæs (model 1).

It is not possible to give an clear conclusion on environmental effects, but it can be concluded that for it is an advantage for certain environmental effects to recycle used stone wool, since a lot of waste is removed from land filling. More energy resources will however be used for transport, causing a greater contribution to air emissions.

Rockwool will need to invest in development and implementation of one ore more tools for control of the used stone wool they receives. Investments are assessed to be around 5 million DKK. The investments will however secure that Rockwool has capacity to receive future amounts of used stone wool.

The extrapolated calculations for 2006 and 2008 shows that the cost of transport as well as the environmental effects will decrease per ton recycled stone wool due to the future increase in amounts. It is also expected that the investment costs at Rockwool per ton recycled stone wool will decrease, since their costs per year does not change regardless of the amount of received stone wool.

A precondition for a successful recycling system that is economically and environmentally advantageous is that sufficient amounts of used stone wool is collected and that it has a quality that can be used by Rockwool without any pre-treatment.

Based on the results of the field investigations, the tests at Rockwool and the calculations and assessments of the recycling models it is recommended to establish a recycling system that follows model 1 in this report.

It is therefore recommended to take the preliminary steps to a dialog and closer discussions with involved partners and stakeholders in such a recycling system in order to make a more concrete and precise framework. It is furthermore recommended to look further into the relevant legislation, the municipal handling of the stone wool fraction in regulations and administrative procedures for recycling.

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Version 1.0 August 2006, © Miljøstyrelsen.