QUOVADIS Project

1. QUOVADIS Project Work Package 6 – Task 6.4Validation of prCEN/TS 15413 (WI 343027) “Methods for the preparation of the test sample from the laboratory sample” Part 2 – Ruggedness testing Aldo Giove – ENEL GEM Area Tecnica Ricerca – Brindisi (Italy) Roma, 24 October 2007

2. Devices for particle size reduction First step Final step or Retsch SM 2000 Cutting Mill Retsch SR 300 Rotor Beater Mill Retsch ZM-1 Centrifugal Mill Size reduction by cutting and shearing forces Low speed  low heating Final particle size depending on the grid/sieve installed; coarse to mid size cutting (order of magnitude: mm) Feed: soft, medium-hard, tough, elastic, fibrous materials Low to mid throughput Size reduction by high speed impact and shear effects High speed  heating may be developed during processing, depending on the type of material Final particle size depending on the grid/sieve installed; mid to fine size cutting (order of magnitude: below mm) Feed: soft, medium-hard, brittle, fibrous materials Low throughput Size reduction by hammering, impact and shear effects High speed  some heating is developed during processing Final particle size depending on the grid/sieve installed; coarse to mid size cutting (order of magnitude: mm) Feed: soft, medium-hard; low performances on tough, elastic and fibrous materials Mid to high throughput

3. Evaluation of the effect of particle size reduction devices (D95 = 0.95 cm) Analyses: CHN: 3 replicates each x 15 independent portions Hg direct: 3 replicates each x 15 independent portions Moisture + ash: 3 replicates each x 15 independent portions Elements (~20, by alkali fusion and ICP-OES): 3 replicates each x 15 independent portions

4. Sub-sampling for evaluation of ruggedness 16 sub-samples (A .. R) of about 50 g each were already been prepared from 1 kg of material (D95=0.95 cm). Five of them (A, D, G, L, O) have previously been used for the verification of the statistical formula. The other nine are used for evaluation of ruggedness: B, C, E for low stress processing; F, I, M, for mid stress processing; P, Q, R for high stress processing. Each sub-sample has been further divided in two aliquots for the different analytical procedures, one for CHN and Hg, the other for moisture, ash and elemental determination.

5. Effect of particle size reduction device on municipal solid waste (QR-D): mass recovery rate Recovery rate is more quantitative for cutting mill SM 2000+ centrifugal mill ZM 1 (“Low” stress processing), while more of 15 % of the mass is lost (as dispersed dust) with the rotor beater millSR 300+ centrifugal mill ZM 1(“Mid" but expecially “High” stress processing). Worst results have been shown by “high” stress method. Definitley low stress processing shows the best recovery in both type of samples. The temperatures developed during Low stress treatment aren’t enought high to cause significat influences on the sample; mid- and expecially high-stress procedures could influence some volatile parameters (i.e. moisture). Low stress processing has the smallest influence on the samples  characteristics.

6. Effect of particle size reduction device: macro-homogeneity on municipal solid waste sample Analytical results performed on the different aliquots of sample have been used to evaluete the actual CV between the “macro” aliquots (homogeneity between the test portions of about 15 g each, obtained by combining results of “micro” aliquots of 1 g each). A qualitative comparison of these values shows that for each parameter the variability between sub-sample (RSD%) is comparable and doesn’t show significant differences due to the processing.

7. Effect of particle size reduction device: micro-homogeneity on municipal solid waste sample Analytical results performed on the different aliquots of sample have been used to evaluete the actual CV between the “micro” aliquots (homogeneity between all the different test portions of about 1 g each) A qualitative comparison of the values shows that for each parameter the variability between test portions (RSD%) is comparable and doesn’t show significant differences due to the processing; Copper values show extremely high variability

8. Application of statistical formula on demolition wood sample (QR-B) Case of 16 sub-samples of 55 g each obtained from the quartering of the original sieved sample, with a shape factor estimated using the dimensions 5x0.5x0.4 cm (s = 0.008). D95 = 0.95 cm. Case of sub-samples of 1 g each (obtained after further quartering) and a shape factor estimated using the dimensions 0.5x0.5x0.4 cm (s = 0.8); D95 = 0.05 cm. (These are the test samples needed of analytical determinations) For major and homogeneously distribuited components (high p-factor) a CV of 0.05 or less is to be expected. For less homogeneously distribuited components (small p-factor) a CV of 0.11 or higher is to be expected. These CV express the level of macro-homogeneity For major and homogeneously distribuited components (high p-factor) a CV of 0.07 or less is to be expected. For less homogeneously distribuited components (small p-factor) a CV of 0.17 or higher is to be expected. These CV express the level of micro-homogeneity

9. Effect of particle size reduction device: macro-homogeneity and loss of volatiles on demolition wood sample For most parameters the variability is significantly affected by the processing: low stress procedure show generally lower variability compared to “high” and “mid” stress procedures. A notable exception regards Pb is due to a sub-sample that has a content ten times higher than all others of this element, explained by possible presence of a single “fragment” of highly contaminated wood.

10. Effect of particle size reduction device:micro-homogeneity on demolition wood sample For each parameter the variability (RSD%) show significant differences due to the processing; “Low” and “Mid” stress procedures differ significantly with “high” stress in the result micro-homogeneity (homogeneity between all the different test portion of about 1 g)

11. Effect of particle size reduction device: loss of volatiles on demolition wood sample Mid- and high- stress processing could lead to some loss of volatiles: moisture values are significantly different between the low-stress processed sample, (treated with cutting mill) and both other series of sample (treated with rotor beater mill) Other parameters don’t show significant differences between low, mid and high stress treatments

12. The cutting mill used in the low-stress procedure shows generally better performances for particle size reduction of SRF compared to the rotor-beater mills, so it should be preferred when possible. Considerations on effect of particle size reduction devices • Loss of analytes: volatile compounds (mainly moisture) can be lost due to the system used for particle size reduction (this effect was not visible in the case of municipal solid waste, maybe due to the heterogeneity of sample that masks significant differences between the procedures). “Low stress” procedure gives higher recovery for moisture compared to the “mid” and “high-stress treatment. For all other parameters, differences between the three treatment procedures are due just to the intrinsic heterogeneity of the sample. • Mass recovery: the “Low-stress” treatment procedure shows the best mass recovery (> 90%), while the “Mid” and “High” stress procedures perform somehow worse. This is due to the different particle size reduction technology used: the cutting mill used in the low-stress procedure develops less dust during processing compared to the rotor-beater mills, so it should be preferred when possible. • Resulting micro-homogeneity and macro-homogeneity appear to be influenced in some way by the system used for particle size reduction (this effect was not visible in the case of municipal solid waste, maybe due to the heterogeneity of sample that masks significant differences between the procedures). Low stress procedure (cutting mill) gave slightly better results. prCEN/TS 15413 ( upgrade to EN 15413)