PROJECT DESCRIPTION
BACKGROUND
Icreasingly, household waste is being disposed of by incineration. Dumping in open landfill is now being restricted more and more, and is banned in France since 2002. This leaves three basic ways of treating household waste : composting, recycling and incinerating. This last solution is developing rapidly as it is also producing energy, although there are some serious environmental problems related to this technology, which is associated by the general public to the dioxins that used to be found in the fumes released from old-fashioned incinerators. Yet today’s modern incinerators are equipped with a module that washes the fumes and extracts the solid residues. One ton of household waste will generate 700 kg of inert fumes, 25-50 kg of fly ashes and 220-270 kg of clinkers. Safe technologies permit the recycling the clinkers (see for example the LIFE project LIFE96 ENV/F/000435), but the ashes washed from the fumes are a very active by-product that need recycling.
OBJECTIVES
The project aimed to develop an innovative treatment process for fly ash and refuse which result from the incineration of municipal wastes. This was aimed at making it possible to end the disposal of such toxic waste in special landfill and to recover a large quantity of products, which are currently lost. Starting with its initial experience in the treatment of used batteries and industrial waste via hydrometallurgical treatment, RECUPYL aimed at developping a new treatment proces for fly ashes, which involved: - a scientific analysis of the problem in hand, - a feasibility study of the new process, - industrialisation and distribution of the process, either via a licensing agreement and assistance with installation, or by developing a partnership with an industrial concern.
RESULTS
From a scientific and technological perspective, it has become clear that hydrometallurgical treatment is essential in eliminating and recovering heavy metals, provided that this form of treatment is combined with other techniques, in particular thermal and mechanical treatment. Hydrometallurgy covers all metal extraction processes involving the creation of a solution (with an acidic or basic solvent), leaching and electrolysis. A hydrometallurgical process includes the following individual operations: - dissolution of the fraction of ore containing the necessary chemical element, - purification and concentration of the solutions, - transformation to metal state. In addition to all of its technical advantages, this process is environmentally friendly, because the hydrometallurgical processes causes practically no atmospheric pollution by the emission of gas, dust or steam. The technology developed by RECUPYL allows a complete treatment of the fly ashes and the enhancement of several by-products. One ton of fly ashes will produce the following recycled elements: - 670 kg of mineral granulate that can be utilised for building roads - 180 kg of salts that can be utilised on roads when these are frozen - 120 kg of gypsum, that can by utilised in the construction industry - 20 kg of zinc and 10 kg of other metals that can be utilised as standard raw material. The environment advantages of the process are as follows : - Dump sites are not invaded by toxic refuse coming from incinerators - Natural resources are preserved by the utilisation of recycled material - Less dangerous waste is carried around on long distances - The public image of incineration is improved. The demonstration phase was successful and the commercial success also seems guaranteed. A treatment line build on the premises of an incinerator, with a treatment capacity of 4000 tons/year will result in a treatment cost of EUR 260 per tonne, very similar to the cost of dumping. The cost per unit will decrease rapidly for a larger capacity and fall well below the cost of dumping. Furthermore, the sale of the recycled material will also help to ensure economical viability.From a scientific and technological perspective, it has become clear that hydrometallurgical treatment is essential in eliminating and recovering heavy metals, provided that this form of treatment is combined with other techniques, in particular thermal and mechanical treatment. Hydrometallurgy covers all metal extraction processes involving the creation of a solution (with an acidic or basic solvent), leaching and electrolysis. A hydrometallurgical process includes the following individual operations: - dissolution of the fraction of ore containing the necessary chemical element, - purification and concentration of the solutions, - transformation to metal state. In addition to all of its technical advantages, this process is environmentally friendly, because the hydrometallurgical processes causes practically no atmospheric pollution by the emission of gas, dust or steam. The technology developed by RECUPYL allows a complete treatment of the fly ashes and the enhancement of several by-products. One ton of fly ashes will produce the following recycled elements: - 670 kg of mineral granulate that can be utilised for building roads - 180 kg of salts that can be utilised on roads when these are frozen - 120 kg of gypsum, that can by utilised in the construction industry - 20 kg of zinc and 10 kg of other metals that can be utilised as standard raw material. The environment advantages of the process are as follows : - Dump sites are not invaded by toxic refuse coming from incinerators - Natural resources are preserved by the utilisation of recycled material - Less dangerous waste is carried around on long distances - The public image of incineration is improved. The demonstration phase was successful and the commercial success also seems guaranteed. A treatment line build on the premises of an incinerator, with a treatment capacity of 4000 tons/year will result in a treatment cost of EUR 260 per tonne, very similar to the cost of dumping. The cost per unit will decrease rapidly for a larger capacity and fall well below the cost of dumping. Furthermore, the sale of the recycled material will also help to ensure economical viability.
