Background The total waste generated by the European stone wool industry is estimated to be between 20 to 60% of the product output. In the EU Member States there are 26 stone wool plants with about 40 stone wool production lines. With a yearly production of 20 000 tons/line on average, these plants generate 160 000 to 480 000 tons of waste in the EU. 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 the melt is not fiberized completely and consequently rejected from the production process. Until now, there has been only one method to reuse this process waste, i.e. briquetting. The waste is ground and mixed with cement to briquettes. However, this “briquetting of waste”, which is described in the BAT reference document for the glass industry, requires rather high initial production costs for machinery and buildings and uses an extra raw material, i.e. cement. Furthermore, the melting of briquettes causes increased atmospheric emission of particulate matter and sulphur oxides because of the impurities in cement. The Paroc enterprise has equipped one of its Swedish plants with the existing BAT for waste recycling (i.e. briquetting). The relatively high production costs and increased air emissions have intensified the need to find alternative techniques for waste recycling. Objectives The main objectives of the “PAROC-WIM” project are: • 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; • to minimise the amount of waste from the manufacturing of stone (rock) wool by injecting the process waste into the melting furnace; • to develop the waste injection machinery to a commercial product available for all stone wool producers, using coke fired melting furnaces (over 90% of the stone wool production lines). The demonstration project is in line with the Community strategy for waste management, 96/399, and with the Sixth Environment Action Programme 2001-2010. Results The "PAROC-WIM" LIFE project has successfully developed a process to feed fine fractioned material directly into the melting zone in a stone wool melting furnace. The acronym WIM stands for "Waste Injection into the stone wool Melting furnace". The best environmental benefits of this process are gained, when it is used for recycling stone wool production waste directly into the melting zone. Other fine fractioned minerals and especially fine fractioned coke can also be fed into the melting furnace with WIM. An additional environmental benefit of this technology is the reduction of melting energy and, therefore, decreased coke consumption and reduction of coke-induced gaseous emissions to the atmosphere. The project has demonstrated a cost efficient alternative to the technique presented in the Reference Document on Best Available Techniques in the Glass Manufacturing Industry (adopted Dec 2001) for recycling production waste in the stone wool manufacturing process and for minimising the amount of waste from manufacturing of stone wool. It was successfully carried out in two Paroc factories; in Oulu, Finland and in Hässleholm, Sweden. Using the WIM process, the prototype at the Oulu factory has achieved the following results: In 2003 almost 80 % of the spinning waste was reused as raw material corresponding to over 7% of the total amount of mineral raw materials. A totally new full-scale pilot plant has been constructed and placed at the stone wool factory in Hässleholm. The best elements of the prototype were used in the pilot plant, in both the design and operational routines. During 2004 the use of spinning waste recycling increased from 80% to nearly 100%. Savings in the raw material has meant a reduced amount of waste delivered to the landfill as well as reduced coke (energy source in melting) and dolomite (prime raw material) consumption. The new technology is being marketed and sold within the Paroc Group and licensed to other stone wool producers. This project has been awarded the title of "Best of the Best" from a shortlist of 21 "Best" LIFE Environment projects in 2005-2006