Recycling of Waste Materials in the Production of Stone Wool for Insulation LIFE98 ENV/DK/000629

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1 Recycling of Waste Materials in the Production of Stone Wool for Insulation LIFE98 ENV/DK/ Project description Environmental issues Beneficiaries Administrative data Contact details: Project Manager: Peter Binderup HANSEN Tel: Fax: Project description: Background Current production methods for stone based mineral wool for insulation requires large quantities of energy and stone material. At the same time, large quantities of waste products from municipal and industrial treatment and production systems are being produced, which are believed to be suited as raw materials and energy sources in the production of mineral wool. Objectives The objective of the project was to perform a full-scale demonstration of the newest technology for recycling waste products as raw material in the production of stone wool based insulation materials (rock-wool). The following results were expected: - a reduction of waste to be disposed of - the production of mineral wool would require less energy and stone based raw materials - increased knowledge of the possibilities for substitution of the primary energy and stone based raw materials with waste products. The designated production lines were to be redesigned with modified sub-systems for running a sequence of tests with alternative raw materials for stone wool production. Specifically, the modifications would be in the feeding process and the environmental process to enable the required additional performance criteria to be fulfilled. The materials planned for testing were: paper sludge, sewage sludge, plastics, coal tailings and metallurgical slags. From an environmental point of view, the

2 technical nature of the project was fourfold: - it would reduce an existing and increasing environmental problem in terms of depositing industrial and household waste in Germany, the Netherlands, France, Denmark, and the UK. - it would increase recycling in the overall circulatory system of waste management by introducing waste materials in the stone wool production - it would reduce the use of natural resources - it would reduce energy consumption Results Waste handling and the agglomeration/briquetting system: In Rockwool Lapinus a new plant for recycling process waste has been established. It is based on a process in which internal Rockwool process waste is mixed with other components, such as secondary raw materials from other industries and stone split, and an organic binder and subsequently formed into briquettes. Initially, problems were experienced, but by improving the quality of the raw materials, especially the milling waste, and by under-roof storage of the briquettes the quality of the briquettes improved significantly. Subsequently a much-improved output was obtained and at the same time the expected coke consumption was realised. Environmental System: The new environmental system was built on Rockwool Ltd s factory in Wales, UK. It is based on a process where a dirty flue gas (containing fly ash) from a melting furnace passes through a combustion chamber. Here CO, reduced S-compounds (i.e. H2S and COS) an N-compounds (NH3, HCN etc.), and tars and other organic remains are oxidized at a temperature above 800 C to combustion products such as CO2, H2O, and N2, as well as the acidic oxides of sulphur and nitrogen SO2 and NOx. The system was commissioned on February 1st The adjustment of the combustion system initially gave rise to some problems, due to fouling of the combustion chamber. Through optimization and improved heat recovery the problems were minimized and the system enabled the use of waste materials containing organic residues. Demonstration series metallurgical slag. In 1998 a joint project was initiated with a Dutch steel producer in order to clarify whether Rockwool Lapinus (Netherlands) could use steel making slag in the charge. The feasibility study revealed that direct charging of steel slag would make the material economically attractive whereas steel slag charged as fines in briquettes would only be relevant if the price of the slag were reduced significantly. Successful trials were carried out using steel slags in briquettes as well as directly charged, i.e. process conditions, product quality, and environmental conditions were not compromised. The present price level of the slags combined with the chemical composition of the material has lead to a systematical use in the charge in Rockwool Lapinus Slag from ferro alloy production in the UK have been melted successfully in Rockwool Ltd s factory in Wern Tarw. However, due to insufficient business potential combined with a too high sulphur content of the slag, further activities in this field have been stopped. Rockwool Ltd. in the UK has successfully demonstrated the utilisation of steel making slag in the charge. The limited sulphur content combined with a high iron and calcium content makes the steel slag an attractive and competitive alternative raw material. The investigation has resulted in a general use of steel slag in Rockwool Lid in the order of 20,000-25,000 t/year. On an EU basis the potential for steel slag etc. is estimated to be in excess of 150,000 t. Although the project shows that the process is technically feasible, it is still uncertain if it is commercially viable. Demonstration series aluminium slags: Rockwool Lapinus in the Netherlands has

3 carried out a feasibility study on the use of aluminium slag, revealing that significant additional investment is necessary in the conventional briquetting factory to secure the internal working environment, due to the presence of aluminium nitrite in the aluminium slag which releases gaseous ammonia when mixed with water during the briquetting process, resulting in the need for extensive ventilation. Tests with external briquettes containing the aluminium slags initially revealed problems with closing the internal waste balance, however since then the situation has improved so much that no additional briquettes containing waste is necessary, after which external briquetting of the aluminium slags would be economically feasible. Remaining problems are related to cross boarder transportation from Germany, where the external briquette manufacturer foreseen is situated Whereas in Germany the aluminium slag is classified as a green waste, in the Netherlands the slag is classified as an orange waste, the import of which is restricted. The aluminium slag is presently used in three of the four German factories at an amount of 26,000-37,000 t per year, thereby replacing some 16,000-25,000 t bauxite. There is also an annual coke saving of about 1,500 t. The recent development of a new product in Deutsche Rockwool has put more focus on some of the product quality parameters. Additional demonstrations with the aluminium slag revealed that the product quality needed for the new products could not be met with the aluminium slag based charge. Although only a limited number of factory lines produces these new products it still proved a potential challenge which needed attention. Demonstration series waste materials with calorific value. In Rockwool Lapinus test runs have followed runs in the new briquetting plant with briquettes containing paper sludge (from a paper mill). This proved not to be economically feasible. Trials carried out in Rockwools Norwegian factory, showed that waste carbon lining could replace % energy, which currently comes from coke, maintaining good process conditions as well as good product quality. The cyanide emission is unaffected by the use of waste carbon lining. The halogen emission can be managed by the addition of hydrated lime or sodium bicarbonate. The fly ash would have to be either landfilled or sold for upgrading. The permanent implementation of waste carbon lining at the Rockwool Factory in Hiltrup is expected to commence in October 2001, with an expected annual consumption of 2,000-3,000 t of waste carbon lining, thereby replacing 1,300-2,000 t of coke. The annual production of waste carbon lining in Germany is 10,000-12,000 t. Deutsche Rockwool would be able to handle all of this in the three factories. By full implementation, Deutsche Rockwool could annually use as much as 20,000 t of the material, however import is restricted as the material is generally classified as a hazardous waste and therefore is preferably treated it within the countries of origin. It is expected that an annual consumption of 30,000-40,000 t of waste carbon lining would eventually be possible, covering Germany, France, Italy, Spain, UK and Norway. This would replace 20,000-25,000 t of coke. Demonstration series of aluminium rich catalytic wastes. The new products in Deutsche Rockwool made it necessary to look for alternative aluminium rich secondary raw materials for some lines. A literature survey revealed that an aluminium rich catalyst waste from the petrochemical industry could be an attractive secondary raw material. In the past large amounts of the material had to be landfilled as no industries were able to use it. The demonstration series have shown that the material may be used in the Rockwool process as a replacement for bauxite and the fibre quality is good enough to produce the new products. The material has no negative impact on the products, on the composition of the fly ashes or on the flue gas emissions

4 potential annual consumption of this waste catalyst material is 12,000 t, thereby replacing 7,000-8,000 t of bauxite. If the material is available in larger amounts at the right price an annual consumption of 25,000 t could be possible in Deutche Rockwool alone. By including Rockwool Lapinus another 25,000 t could be realistic. This would give a total annual consumption of about 50,000 t of aluminium rich catalyst waste, which would correspond to a bauxite saving of some 30,000 t. Environmental issues addressed: Themes Waste - Industrial waste Waste - Waste use Keywords use of waste as energy source energy saving recycling potential reuse of materials iron and steel industry insulating material alternative technology Target EU Legislation Land & Soil "Directive 86/278 - Protection of the environment, and in particular of the soil, when sewage slu... Waste Directive 1999/31 - Landfill of waste ( ) Natura 2000 sites Not applicable Beneficiaries: Coordinator Type of organisation Rockwool International A/S International enterprise

5 Description Rockwool International A/S is a private company, producing insulation materials for the building insustry. The company has production facilities in several countries (23 factories in 14 countries). Administrative data: Project reference LIFE98 ENV/DK/ Duration 01-NOV-1998 to 01-MAY Total budget 2,615, EU contribution 578, Project location Københavns amt(danmark) Limburg(Nederland) Project description Environmental issues Beneficiaries Administrative data Read more