Interim LCA comparison of metal working fluids with and without Chlorinated paraffins

Stig Irving Olsen, Frans Møller Christensen

    Research output: Book/ReportReportResearch

    Abstract

    The present report constitutes deliverable D 19 and D 23 of the OMNIITOX project and is the life cycle assessment part of the ECB case study (work package 5). The objectives of the case study have been to deliver empirical knowledge for the feasibility study carried out as part of WP5 and to deliver data and inspiration to other work packages (WP 7, 8 and 9). Specifically for this part of the case study (life cycle assessment part), the aims have been to apply LCA for comparing the use of different alternative substances in a specific application and to make a basis for comparison with the EU risk assessment approach for assessing the same substances. In the other part of the case study (Deliverable 9; Christensen & Olsen, 2002), the results of the Risk Assessments are summarised. In the original problem definition focus were on the use of SCCP and as an alternative MCCP in metal working fluids (MWF), however since SCCP is largely substituted this was not possible. The LCA therefore focus on a comparison between a MWF containing MCCP and an alternative MWF containing sulphurised compounds. The product studied for the LCA is chosen by the cooperating company (company identity presently considered confidential) and it is a product for which it is necessary to use an extreme pressure metal working fluid (which is the main use of MCCP). The product chosen for study object is stainless steel tubes for use in e.g. heat exchangers. The functional unit of this study is 1 tonne stainless steel tube with an outer diameter of 19.5 mm and material thickness of 1.65 mm (corresponding to approx. 1340 m tube). The tube is used as a heat-exchanger tube and the quality named 2205. The study has focused on European based operations since most known processes in the product system takes place in Western Europe. All background processes, such as electricity production, are based on average technology. This is also valid for most processes upstream the supplier of metal working fluid, for which LCA data to a high degree has been estimated on the basis of available LCA data on comparable processes/products. To a certain extent the suppliers of raw materials have delivered data but not specific LCA data for their materials. As far as possible the study traces back all materials to elementary inputs (i.e. inputs from the nature) but estimates are used to a great extent. Transport has only been estimated for the MWF raw materials to the producer of MWF. Transport from MWF supplier to the company is assumed to be identical for the two alternatives. All energy data has been taken from the LCAiT database, so e.g. electricity is European average from 1994. The MWFs used are produced in Sweden and data has been supplied concerning the production and the use of raw materials. Information on the composition and in some case modest information on production of raw materials has been gathered. Many of the raw materials are based on some fatty acid esters and data for these esters are estimated from the production of rape seed oil methyl ester. Additionally data for detergent grade chemicals has been included as estimates for some of the components of the MWFs. Data on steel production and on electricity and transport are taken from the LCAiT data base. The tube manufacturing company was not able to provide process data. These have therefore been estimated from comparable processes in other data bases. They could however provide an estimate of the additional energy and steel required when using the alternative MWF (metal working fluids) as well as an estimate of the amount of MWF used per tonne of steel.The use and disposal stages of the steel tubes have been omitted since they are identical for both alternatives. The inventory results calculated using the software tool LCAiT are given in the appendices. Impact assessment has been performed using the CML method with current available characterisation factors. However for a selection of compounds in the inventory, the impact categories ecotoxicity and human toxicity have further been evaluated by several methods (EDIP, USES-LCA (CML), CALTOX, and Impact 2002) as an input to WP7 after a gathering of substance data for calculation of (eco)toxicity characterisation factors. The results of the impact assessment show that there are only minor differences between the two alternative systems. The differences are due to a slightly larger use of energy and steel in the production of tubes when using the non-chlorinated alternative to MCCP based MWF, i.e. a slightly less environmental impact from the MCCP containing MWF. However, differences in energy use etc. depend highly on the energy estimates which may be somewhat uncertain. Furthermore, the results show that, impacts from electricity and steel production and consumption during MWF application (the pilgering process) dominates over the impacts related to the production of the MWF itself, which is only a minor contributor to the total life cycle impact. Although the MWFs in themselves only contribute slightly to the overall life cycle impacts, it was found relevant to compare the production of these. It is seen that their impacts do not differ significantly. The assessment of selected substances with several methods for LCIA toxicity assessment did not introduce any other significant environmental differences between the two alternative MWFs. It can be concluded that the small differences between the two systems studied cannot be interpreted as significant. The lack of difference between productions of MWFs was to some degree expected since most raw material data has been estimated using the same background data. One of the main objectives of the LCA case study was to examine the possible higher energy consumption in metal working processes using the non-chlorinated alternative. The preliminary results in this report suggest that these differences are insignificant. However, due to the limited amount of specific data, this conclusion should be considered carefully. Better data for energy and steel consumption will be searched for and possibly included in the final report. In Risk Assessment of chlorinated paraffins, a risk has been associated with the emissions of MWFs from metal working operations. Since the actual company collects spent MWFs and incinerate these, emissions are not expected to occur except from diffuse losses. The diffuse emissions have not been estimated but could give rise to a higher toxic impact from the MCCP containing MWF. A sensitivity analysis of this will be made in the final report.
    Original languageEnglish
    Number of pages14
    Publication statusPublished - 2002

    Keywords

    • Chemicals
    • Life cycle impact assessment
    • Life cycle inventory
    • case study

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