Charac te r i za t ion o f recyc led gypsum

Jiménez-Rivero, A., García-Navarro, J.

G R U P O D E I N V E S T I G A C I Ó N S O S T E N I B I L I D A D E N L A C O N S T R U C C I Ó N Y E N L A I N D U S T R I A

4 t h I N T E R N A T I O N A L C O N F E R E N C E o n S u s t a i n a b l e S o l i d W a s t e M a n a g e m e n t , L i m a s s o l - C Y P R U S 2 0 1 6

Prof. Justo García Navarro, Dr. Arquitecto

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1. INTRODUCTION

2. METHODOLOGY

3. RESULTS AND DISCUSSION

4. CONCLUSION

TABLE OF CONTENTS

Introduction - Methodology – Results and discussion - Conclusion

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An estimated amount of 1.9 million tonnes of post-consumer plasterboard waste was generated in the EU-27 in 2013b, of which only 6% was recycled into plasterboard.

Therefore, the use of recycled gypsum (RG) is still very low in the EU. For example, the weight percentage of post-consumer RG in a reference plasterboard was recently estimated to be 1%.

Around 4/5a of gypsum products manufactured in the EU is plasterboard.

a Eurostat, 2012b Eurostat, 2012 and GtoG DA1 report

CURRENT SITUATION

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TOWARDS A NEW APPROACH

In a circular economy…

post-consumer waste is effectively collected, recycled and used to make new products;

virgin raw materials are used only when secondary raw materials are not available.

The waste chain needs to be upgraded in order to maximize recyclable gypsum waste and ensure quality recycled gypsum.

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GtoG PROJECT

Life+ GtoG Project ENV/BE/001039:

“From Production to Recycling, a Circular Economy for the European Gypsum Industry with the Demolition and Recycling Industry”

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GTOG IMPLEMENTATION ACTIONS

The works included pilot projects in distinct European locations: Belgium, France, Germany, the Netherlands and the United Kingdom, in the stages part of the deconstruction-recycling value chain.

Deconstruction

Recycling

Recycled gypsum ready to be reincorporated into the plasterboard manufacturing process was then obtained.

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GTOG IMPLEMENTATION ACTIONS

21 gypsum feedstock samples were tested. Business-as-usual feedstock (GYBAU) was compared to recycled

gypsum feedstock (GYRG).

GYBAU:Conventional gypsum as currently used in the EU manufacturing plants: 4 samples from plants using mined gypsum, 3 samples from plants using FGD, 1 sample of pre-consumer recycled gypsumSamples supplied by 5 gypsum manufacturers in BE, DE, FR (2), UKN=8

GYRG:100% recycled gypsum from pre and post-consumer sourcesSamples supplied by 2 gypsum recyclers operating in BE, FR, NL, UKN= 13

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MAIN OBJECTIVE OF THIS STUDY

To analyse relevant parameters that characterize gypsum as a raw material (business-as-usual (BAU) gypsum feedstock and recycled gypsum (RG) feedstock).

The samples were collected by LOEMCO (Official Laboratory for Testing Materials of Construction, third party laboratory, partner of the GtoG project) during the GtoG project, between February 2014 and January 2015.

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METHODOLOGY

Gypsum as feedstock: recycled gypsum quality criteria

The experimental methods based on four European documents:

The Instruction Sheet VGB-M 701: free moisture, purity, salts and pH;

The European Standard EN 933-1: particle size results;

EN 13137: total organic carbon (TOC); EN ISO 11885: toxicological parameters; Radioactivity index according to the RP 112

document (EC); Asbestos content according to the Rietveld

method .

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RESULTS

PARTICLE SIZE

GYBAU and GYRG had similar maximum size. However, the deviation was higher for the case of GYBAU.

Note:

Variations in the particle size distribution of feedstock may affect the calcination rate. Thus, the particle size of RG should be in line with the conventional feedstock used by the manufacturer.

Parameter UnitGtoG project guidelines

Maximum size mm 15.00

Free moisture % w/w <10

Purity % w/w >80

Total organic carbon % w/w <1.5

Magnesium salts % w/w <0.1

Sodium salts % w/w <0.06

Potassium salts % w/w <0.05

Soluble chloride % w/w <0.02

pH - 6-9

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RESULTS

FREE MOISTURE

The average free moisture obtained for GYRG is 6.91% w/w. The value was above the threshold (10 % w/w) in 3 of the 13 GYRG samples.

Note:

Reincorporation of RG with high free moisture content may involve additional energy use and cost. As a consequence, the Eurogypsum Recycling Working Group recommends to limit free moisture of RG to 5%.

Parameter UnitGtoG project guidelines

Maximum size mm 15.00

Free moisture % w/w <10

Purity % w/w >80

Total organic carbon % w/w <1.5

Magnesium salts % w/w <0.1

Sodium salts % w/w <0.06

Potassium salts % w/w <0.05

Soluble chloride % w/w <0.02

pH - 6-9

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RESULTS

PURITY

The average purity of GYBAUwas 4.37 % w/w higher compared to GYRG. In all cases >80% w/w.

Note:

Purity affects the energy use of the calcination stage during the manufacturing process, due to the content of chemically bound water. The Eurogypsum Recycling Working Group recommends a value of at least 85% .

Parameter UnitGtoG project guidelines

Maximum size mm 15.00

Free moisture % w/w <10

Purity % w/w >80

Total organic carbon % w/w <1.5

Magnesium salts % w/w <0.1

Sodium salts % w/w <0.06

Potassium salts % w/w <0.05

Soluble chloride % w/w <0.02

pH - 6-9

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RESULTSTOTAL ORGANIC CARBON

In this study, one of the GYRGsamples exceeded the TOC threshold in the GtoG guidelines on RG quality criteria*.

Note:

High TOC values affect the fluidity of the slurry and increases the excess of water demand. The residual paper should therefore be kept at the minimum possible level. The Eurogypsum Recycling Working Group recommends TOC below 1.0% w/w.

Parameter UnitGtoG project guidelines

Maximum size mm 15.00

Free moisture % w/w <10

Purity % w/w >80

Total organic carbon % w/w <1.5

Magnesium salts % w/w <0.1

Sodium salts % w/w <0.06

Potassium salts % w/w <0.05

Soluble chloride % w/w <0.02

pH - 6-9*was attributed to the nature of the sample, as it turn out that RG-01 corresponded to only pre-consumer RG

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RESULTS

WATER SOLUBLE SALTS AND PHThe only sample that presented a high TOC content also showed a high sodium (0.066% w/w) and chloride (0.124% w/w) content. On the other hand, the pH value complied in all cases.

Note:The presence of soluble salts affects the paper bonding in plasterboard production.

Parameter UnitGtoG project guidelines

Maximum size mm 15.00

Free moisture % w/w <10

Purity % w/w >80

Total organic carbon % w/w <1.5

Magnesium salts % w/w <0.1

Sodium salts % w/w <0.06

Potassium salts % w/w <0.05

Soluble chloride % w/w <0.02

pH - 6-9

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RESULTS

TOXICOLOGICAL PARAMETERSSurprisingly, only 88% of GYBAUand 77% of GYRG samples complied with the GtoG guidelines. Three samples exceeded the nickel content.

Analysis was repeated by a third party laboratory. Discrepancy between the results suggests that further investigation is needed on the procedures and testing methods for trace elements .

Parameter Unit GtoG project guidelines

As mg/kg <4.0Be mg/kg <0.7Pb mg/kg <22.0Cd mg/kg <0.5Cr mg/kg <25.0Co mg/kg <4.0Cu mg/kg <14.0Mn mg/kg <200.0Ni mg/kg <13.0Hg mg/kg <1.3Se mg/kg <16.0

Te mg/kg <0.3

Tl mg/kg <0.4V mg/kg <26.0Zn mg/kg <50.0Asbestos yes/no noR index < 0.5 < 0.5

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The present work has analysed data from testing gypsum feedstock(business-as-usual, BAU and recycled gypsum, RG).

CONCLUSION

In order to obtain quality recycled gypsum, most of theseparameters can be typically managed by the deconstruction-recycling value chain (e.g. free moisture, total organic carbon),by applying effective deconstruction processes (i.e. dismantling,separate collection), and adequate recycling procedures andequipment.

The procedures and testing methods for trace elements must befurther investigated in order to achieve harmonized criteria.

In any case, technical parameters should be adapted to theneeds of each plant (specific manufacturers’ requirements) andvalues should be periodically monitored.

http://gypsumtogypsum.org/