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LIFESO2ZEROEF - Reduction of SO2 emissions by a zero-effluent wet desulfuration process using MgO by-products (LIFESO2ZEROEF)

LIFE13 ENV/ES/000605


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Contact details:

Contact person: José Antonio APARICIO
Tel: 34948421633
Fax: 34948304253
Email: j.aparicio@magnesitasnavarras.es



Project description:

Background

Sulphur oxides (SO2) are produced during the calcination process of magnesite, mainly from the fuel used in the combustion furnace. SO2 is classified as an atmospheric pollutant due to its contribution to acid rain, which is a significant problem in Europe and in the east coast of North America. For this reason, the magnesium oxide (MgO) industry is included within the polluting industries group, and consequently it must fulfil specific regulations. The traditional processes used to reduce the SO2 emissions are based on dry or wet desulphurisation technologies. The difference lies in the way of introducing the absorbent. Dry technologies use a solid or semi-liquid absorbent, while wet ones use an absorbent solution. The Best Available Technologies (BAT) conclusions for the production of cement, lime and magnesium oxide were approved on 26 March 2013. The BAT establishes that dry technologies can be used only if the use of wet technologies is not viable – i.e. because the efficiency in SO2 emissions reduction is higher for the wet desulphurisation process. The main problem with wet technologies is the high water consumption (5-12 m3/tonne) and the generation of a wastewater effluent with a high sulphate content.

In this context, it would be beneficial to test the viability of a ‘zero waste’ wet desulphurisation technology. The use of MgO-based reagents would give value to the effluent generated and ensure that it does not represent a risk to water contamination or present other environmental problems.


Objectives

The main goal of the project was to construct a wet desulphurisation demonstrative plant, on an industrial scale, using MgO-based reagents. This plant would treat the whole combustion gases generated (60 000 Nm3/h) in one of the magnesite calcination rotary furnaces, which is located in MAGNA industrial plant.

Specific project objectives were to:

  • Demonstrate a reduction of emissions of SO2 at the furnace exit below a threshold of 400 mg/Nm3 using MgO slurry as an absorbent;
  • Incorporate a new evaporation step for the generated effluent, with the aim of obtaining a solid residue of magnesium sulphate (MgSO4) and minimise the effluents that are generated at the end of the process;
  • Characterise the MgSO4 generated as a residue, and to study its recovery as a component of fertilisers;
  • Reduce water consumption by means of the condensation of the generated water vapour and its subsequent re-use in the process, that will result in the reduction of the volume of effluent generated;
  • Test and communicate the new technology so that it can be considered a Best Available Technique (BAT) in the next update of the BAT Reference Document for the Production of Cement, Lime and Magnesium Oxide (CLM BREF); and
  • Demonstrate the applicability of this technology and its possible transfer to other areas with similar environmental problems.


Results

The main objective of the LIFE SO2ZEROEF project was to construct a wet desulphurisation demonstrative plant, on an industrial scale, using MgO based reagents. This plant was expected to treat the whole combustion gases (60 000 Nm3/h) generated in one of the magnesite calcination rotary furnaces located in the beneficiary’s industrial plant. It aimed to reduce the SO2 emissions below a threshold of 400 mg/Nm3 using MgO slurry as an absorbent. The project has not achieved these main objectives because MAGNA was unable construct a wet desulphurisation demonstrative plant on an industrial scale due to the lack of permits. The permits needed to construct the new desulphurisation plant were still pending (IEA and building licence). Although the new technology met the requirements of the local government of Navarra regarding SO2 emissions, the effluent that would be generated by the plant was not expected to meet the required wastewater discharge limit for the Arga River.

Nevertheless, the project beneficiary decided to continue the project on a pilot plant. MAGMA considers that the wet desulphurisation technology was successfully validated on this scale, and it intends to implement the technology at its industrial plant by 2019. The main conclusion obtained from the monitoring of the pilot plant was that the wet desulphurisation technology is able to reduce the SO2 emissions from 7 000 mg/Nm3 to values below to 400 mg/Nm3. Moreover, the effluent generated in the wet desulphurisation process can be crystallised to obtain magnesium sulphate (MgSO4) waste that can be used as fertiliser.

The technology was also shown to reduce the sulphate concentration in the generated effluent to a below 500 mg/l. It furthermore reduces water consumption by 75% with respect to other wet desulphurisation technologies.

This new technology could be a feasible alternative to the traditional dry desulphurisation process to reduce the SO2 emissions, minimising the environmental impacts. Therefore, it could be fostered as a Best Available Technology (BAT) of cement, lime and magnesium oxide. The technology is in line with the European Directives (2010/75 EU, 2008/50/EC, 2001/81/EC, 2001/80/EC and Directive 93/12/EC) and the Geneva Convention on Long-Range Transboundary Air Pollution. The beneficiary intends to include this new technology in the next update of the BAT Reference Document for the Production of Cement, Lime and Magnesium Oxide, as outlined in its After LIFE+ plan.

Furthermore, the technology offers a range of social and economic benefits. The reduction of SO2 emissions will improve the air quality and minimise acid rain, and thus benefit human health, while the water quality of the Arga River will improve as a result of the reduction of the wastewater effluents. Also, the use of reagents based on MgO (waste from the current process) will lead to a reduction in the amount of waste produced. Moreover, the implantation of the new technology will improve the competitiveness of the company, due to the optimisation of the resources and the possibility of obtaining a marketable sub-product (MgSO4). New jobs could potentially be created to the benefit of the local economy.


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Environmental issues addressed:

Themes

Industry-Production - Metal industry
Waste - Waste use
Air & Noise - Air pollutants
Environmental management - Cleaner technologies


Keywords

acid rain‚  waste use‚  emission reduction‚  air pollution‚  metal products industry


Target EU Legislation

  • Industry and Product Policy
  • Directive 2010/75 - Industrial emissions (integrated pollution prevention and control) (24.11.201 ...
  • Air
  • Directive 2001/80 - Limitation of emission of certain pollutants into the air from large combusti ...
  • Directive 2001/81- National emissions ceilings for certain atmospheric pollutants (23.10.2001)
  • Geneva Convention on Long-range Transboundary Air Pollution (CLRTAP) (13.11.1979) and Decision (8 ...
  • Directive 2008/50/EC - Ambient air quality and cleaner air for Europe (21.05.2008)

Natura 2000 sites

Not applicable


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Beneficiaries:

Coordinator MAGNESITAS NAVARRAS, S.A.
Type of organisation Large enterprise
Description MAGNESITAS NAVARRAS, S.A is one of Spain’s principal producers of calcined magnesite for use in fertilisers and animal nutrition.
Partners None

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Project reference LIFE13 ENV/ES/000605
Duration 02-JUN-2014 to 30-JUN -2016
Total budget 2,535,288.00 €
EU contribution 855,144.00 €
Project location Navarra(España)

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Read more:

Project web site Project's website
Publication: After-LIFE Communication Plan After-LIFE Communication Plan
Publication: After-LIFE Communication Plan After-LIFE Communication Plan (Spanish version)
Publication: Layman report Layman report (Spanish version)
Publication: Layman report Layman report

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Project description   Environmental issues   Beneficiaries   Administrative data   Read more   Print   PDF version