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|INVOLVEMENT OF LIMOUSIN IN ENVIRONMENTAL MATTERS|
1. The « Water and Environment » Centre of Excellence
For over twenty years, Limousin has developed an economy linked to the environment. In order to improve the relationship between industry and environment, the region offers a variety of activities, especially in the water sector but also in relation to air, waste and soil which rely on three components:
Together, these activities make up a major centre of excellence, recognised nationally and internationally, and which is supported and developed by the Limousin Region and its Regional Development Agency.
The centre started in 1997 on the initiative of the CEO of Faure Equipements, specialists in designing and manufacturing filter-presses. The idea was to gather together local skills in the field of water treatment, in order to promote a field of activity that is very well represented and diverse in Limousin and which would include a wider group of professions (manufacturers, design departments and training) connected to all aspects of the environment (water, air, soil, waste, energy, etc.). In 1998 and 1999, a dozen companies were represented at the POLLUTEC trade fair in Lyon and in Paris on a local collective stand which pooled many types of know-how and which enabled a concerted response to be made to the growing market demand for environmental technology.
The dozen companies were aware that communication about the environment in which they work – along with training units and research laboratories, design, engineering and consulting departments, other designers and manufacturers – is as important as promoting their own products or services. These local players have pooled their understanding and their skill so that they are stronger and more competitive in attacking more distant markets.
The various members in the « Water and Environment » Centre of Excellence are:
Training and Research
Studies and Services
Designers and Manufacturers
2. Technical Achievements
The change in outlook towards the environment has become a real issue for manufacturers. As a result, increasing numbers of companies have positioned themselves in the sector. One such company is CALLISTO in Limoges, whose activity is focussed on the problems of industrial water use and discharges. As ceramics is a long-established industry in Limousin, it was natural that CALLISTO would work with the sector and some of the companies they have worked with include:
KPCL (IMETAL Group)
After different studies and a major restructuring aimed at separating uncontaminated rainwater, the manufacturer has set up a treatment facility for process effluent and contaminated rainwater.
Effluent generated by ceramics industries typically contains coarse and fine suspended matter and may also contain products used during production, such as deflocculation agents. Effluent treatment has been in operation since 1996 and for a nominal capacity of 15 m3/h includes:
FERRO COULEURS FRANCE
Faced with increasing environmental regulation and taking account of discharges into the urban wastewater system, this company has adopted an approach aimed at reducing the volume of effluent and at renovation and improving the reliability of treatment facilities for these effluents.
Certain processes (air washing, cooling, etc.) have had their recycling times reduced. The process and the treatment structures with a nominal capacity of 20 m3/h have been resized with, amongst others:
ALLIA (METRA group)
After studies, replacement of the existing treatment plant by a plant with a nominal capacity of 3.5 m3/h including:
This treatment enables a significant reduction in the waste generated and can lead to re-using some of the treated water for certain washing phases. All of this work enables discharges to be reliable and the regulatory and contractual orders to be complied with.
In addition to the above work carried out with CALLISTO, ALLIA, which is in the process of obtaining ISO 14001 certification, has already invested significantly in the environment. For example, the company reuses fired waste material in the form of calcine clay after grinding. ALLIA has also invested in dry-glazing consoles to avoid dust discharges into the atmosphere and in the factory.
It is worth noting that in the three cases shown, the raw effluent is loaded with dense and abrasive suspended matter. Other characteristics of the effluent vary significantly from site to site and require a specific approach which takes into account such parameters as COD, metals, phosphates, nitrites, etc.
Source: « Effluent Treatment in Various Ceramic Businesses » – CALLISTO
3. Energy Consumption
The ceramic industry uses enormous amounts of energy because of the essential nature of the different stages of firing (first firing, glaze firing and decorative firing(s)). It also uses different types of fuel, mainly gas and electricity. In recent years enormous progress has been made in reducing the amount of energy consumed. Developments in kiln burners have resulted in sharp increases in efficiency, which translate into reduced fuel consumption. Control systems have also improved, enabling more efficient mixes of gas and air and therefore better control of firing atmosphere. As a result, companies like DORALAINE have changed the control systems on all their kilns and reduced energy consumption. Other companies are also interested in reducing energy costs by investing in heat recovery from kilns to supply dryers or by increasing the emissivity of the kilns by installing new ceramic coatings on the walls.
4. Solid Waste in the Ceramics Sector
One problem for those industries using traditional casting techniques lies in the disposal of the plaster moulds that represent a major amount of waste for the sector. SVE ONYX, which salvages most of the industrial waste in the region, is currently developing a grinder for the plaster, enabling the plastic spacer lugs of the moulds to be separated by a system of screens. The recovered plaster can then be reused for other activities. In particular, it is possible to use them in the manufacture of plaster partitions, in crop-dusting or as charges in kilns in cement-works.
Although initiatives have been taken in the ceramics sector to reduce the quantity of waste and to reuse the by-products, it remains difficult to dispose of certain types of waste, such as used sludge. Research has shown that, in certain circumstances, it is possible to reuse all or part of this sludge in the manufacturing process. This is the case in the field of floor/wall tiles, roof tiles or bricks, where companies succeed in recycling their waste.
Research in recycling does not stop with the reuse of waste in the manufacture of finished products, but calls on state-of-the-art technology. Thus, SPCTS, the Science of Ceramic Techniques and Surface Treatment Laboratory at the University of Limoges, is developing a technique for recycling and reusing some forms of waste by plasma arcing.
5. Solid Waste Treatment using Plasma Arcing
As already discussed, legal requirements governing the environment, waste management and waste disposal have significantly increased in recent years. Nowadays it is not sufficient to simply destroy the pollutants, they should be treated where possible in order that they can be reused as a future source of raw materials.
Five types of treatment exist for household waste: landfill, incineration, selective sorting, biological treatment and thermal cracking. Since the aim is to reuse as much as possible and to avoid pollution, it is clear that these techniques cannot, by themselves, provide a solution to the problem. The plasma technique, developed in the 1980s, is different to more common thermal techniques in that heavy and volatile metals can be recovered and recycled. Furthermore, the use of thermal plasma allows a waste chemistry to be developed independent of the thermal source to produce light molecules by pyrolysis, while making inorganic waste inert. Although the treatment plants tend to be modest in capacity, the system boasts significant treatment speeds compared to more common techniques operating at similar capacities.
Waste from purification treatment (scrubbing) of exhaust gases from household waste incinerators (known as REFIOM in French) is difficult to dispose of because it is heavily loaded with heavy or volatile metal salts as well as toxic species such as phosphates and dioxins. As the aim is to have a « zero pollutant » at the end of the treatment chain, it is necessary to use a technique that is capable of rendering inert waste with very different compositions. In addition, because of its composition REFIOM could become a significant source of metallic raw materials. Thus, REFIOM has been treated by transferred arc in a plasma kiln in a controlled atmosphere. Continuous supply enables the transformation of REFIOM into a glass, while eliminating undesirable metal species and destroying toxic organic molecules. At the end of the treatment, the resulting glass is metal-free and only inert gases are released. The vaporised metallic species are collected, dissolved and treated by wet process in baths. The metals are extracted and reused in the metallurgical chain, which helps to reduce the treatment cost. The vitreous matrix, free of pollutants, is no longer considered as waste and becomes a usable material, such as aggregate for roads. Plasma techniques are also suitable for the destruction of organo-chlorinates and fluorides. The technique can ensure the destruction of these species so that discharged quantities are well below the critical threshold of toxicity. Thus, only light or inert gas molecules are emitted, thereby limiting any pollution.
Although, in general, thermal techniques enable vitrification and the production of good quality glasses, the plasma technique is the only one to date capable of ensuring a selective evaporation of heavy and volatile metals from the vitreous matrix. In comparison with other known solutions, these techniques offer the best guarantees in terms of efficiency from the point of view of rate of toxin destruction, which has obvious possibilities in relation to economic profitability.
Source : SPCTS (Science of Ceramic Techniques and Surface Treatments)
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