The main objectives of the Paroc-WIM-project are:

1) to demonstrate a cost efficient alternative to the technique presented in the BAT Reference Document for recycling production waste in the stone wool manufacturing process

2) to minimise the amount of waste from manufacturing of stone (rock) wool by injecting the process waste into the melting furnace

3) to develop the waste injection machinery to a commercial product available for all stone wool producers. The project demonstrates technical, economical and environmental benefits of this method compared to the "BAT-technology".

Paroc has engineered the waste injection prototype machinery at its plant in Oulu (Finland) for recycling stone wool production waste. The present prototype still needs some adjustments before the first complete machinery can be constructed and implemented into industrial use. The actions planned in order to complete the machinery for waste injection are as follows:

1) to modify the prototype including follow up of the process parameters and measurement of air emissions

2) to design and manufacture the complete full scale machinery for the plant in Haessleholm (Sweden), Implementing the new machinery includes test runs as well as follow-up of the process parameters and measurement of air emissions

3) to create and disseminate information material to support commercialising of this new technique to be widely available for all stone wool manufacturers.

The demonstrated technique can be used at all stone wool production lines, with coke fired melting furnaces (over 90 % of the stone wool production lines). This new method can utilise about 50% of all wastes generated in stone wool production. The use of virgin rock decreases with about 15 % due to recycling of waste. The new method reduces emission of sulphur and carbon oxides.

This new technology offers significant economic and environmental benefits in comparison to the technology for recycling of waste in stone wool production presented in the BAT Reference Document for Glass Industry.

The Paroc WIM project is in line with the principles expressed in the Communication 96/399 adopted by the Commission in July 1996 on the updated Community strategy for waste management. In line with the Commission strategy there is a general effort by the national and municipal authorities as well as the industry to minimise the amount of waste dumped on a waste disposal site.

The facts of waste, generated in stone wool production in Europe are taken from the IPPC, Reference Document on Best Available Techniques in Glass Manufacturing Industry. The total waste generated in the European stone wool industry is estimated to 20 to 60% of product output. In practice this means 160 000 to 480 000 tons of waste in the EU from 40 production lines with in average 20 000 tons/line yearly production.

The major part of the waste comes from the fiberizing process. When the spinning machine fiberizes molten material, a mixture of different types of rock, about 10-20 % of melt is not fiberized completely and consequently rejected from the production process. A stone wool line with a yearly wool production of 20 000 tons generates 2000 to 5000 tons of fiberizing waste per year. Until now there has been only one method to re-use this waste. The waste has been ground and mixed with cement to briquettes. The briquettes are hardened before use as raw material in melting process in order to act in the same way as rock.

This method is also described in the BAT Reference Document. Briquetting of waste requires rather high investment costs in form of machinery and building. Melting of cement-consisting briquettes causes higher atmospheric emissions of particulate matters and sulphur oxides than melting of virgin rock due to impurities in cement.

Value for money – environmental cost/benefit ratio

The melting costs with waste injection will be about 27 % lower in comparison to using only virgin stone and 16 % lower when compared to using briquettes together with stone (see chart above).

The savings in melting energy in comparison to virgin rock will reduce the carbon dioxide emission with about 4 %.

Using briquettes together with stone causes about 50% increase in emission of sulphur oxides depending on sulphur content in rock and cement used. The demonstrated waste injection will reduce the sulphur emission with 10-15 % compared ton use of virgin stone. The investment costs for waste injection is only 20% of costs for briquetting equipment including the necessary buildings.

The data presented in the charts are based on experience from the one Paroc plant using virgin stone+briquetting. The waste injection data is based on experience from prototype and calculations.