Production of lightweight fillers (LWFs) from recycled glass and paper sludge ash (PSA)

Transcription

1 Symbiosis 2014 International Conference, Athens Production of lightweight fillers (LWFs) from recycled glass and paper sludge ash (PSA) Charikleia Spathi a,b, Luc Vandeperre a, Chris Cheeseman b a Department of Materials, Imperial College London b Department of Civil and Environmental Engineering, Imperial College London

2 Background to the project EPSRC Industrial Case PhD Award Mixed colour glass cannot be reprocessed Sustainable solutions for PSA required as an alternative to landfill Manufacturing LWFs from waste glass and PSA would be a novel re-use application

3 Background to the project EPSRC Industrial Case PhD Award Mixed colour glass cannot be reprocessed Sustainable solutions for PSA required as an alternative to landfill Manufacturing LWFs from waste glass and PSA would be a novel re-use application Industry demand for lightweight fillers (LWFs) and cenospheres

4 Industrial Project Collaborators

5 ENERGY Life cycle of paper Distribution Printing RECOVERED PAPER PULP Paper End users Chemical pulp PAPER SLUDGE PSA Energy production

6 ENERGY Life cycle of paper Distribution Printing RECOVERED PAPER PULP Paper End users Chemical pulp PAPER SLUDGE PSA Energy production

7 Paper Sludge Ash (PSA) Residue from combustion of wastepaper sludge 125,000 tonnes of PSA was produced in ,000 tonnes beneficially reused in UK markets 37,000 tonnes landfilled Increasing volumes produced and opportunity for new applications Material for combustion Amount (tonnes/year) Paper sludge 275,000 Biomass (virgin and clean non-virgin timber) 120,000 Plastics 17,000 Waste Protocols Project: A technical report on the production and use of PSA (2007)

8 Waste glass & PSA: Chemical and mineralogical composition X-Ray Fluorescence data SiO 2 CaO Na 2 O MgO Al 2 O 3 K 2 O Fe 2 O 3 SO 3 TiO 2 P 2 O 5 Others Waste glass nd nd - PSA nd X-Ray Diffraction data

9 PSA: Microstructure Agglomerated particles Loosely bonded Porous

10 dl/lo (%) PSA: Dilatometer results 0-5 Samples fall apart at T= 1180 C Inadequate sintering As-received PSA Temperature ( C)

11 dl/lo (%) PSA and recycled glass: Dilatometer results 0-5 T onset = 594 C, T end = 664 C dl/l o = 23.2 % Recycled Glass As-received PSA Temperature ( C)

12 PSA: Thermogravimetric Analysis (TGA)

13 PSA: Thermogravimetric Analysis (TGA) T onset = 600 C, T end = 780 C m loss = 5.5 wt% CaCO 3 CaO + CO 2

14 Mechanisms for expansion during rapid sintering Green particle particle packing

15 Mechanisms for expansion during rapid sintering Green particle Liquid phase sintering Heating particle packing vitreous phases formed

16 Mechanisms for expansion during rapid sintering Green particle Liquid phase sintering Gas evolution particle packing vitreous phases formed

17 Mechanisms for expansion during rapid sintering Green particle Liquid phase sintering Rapidly sintered particle Gas evolution particle packing vitreous phases formed closed cell structure

18 Specifications of potential LWF products Desired properties Low density ~ < 1 g cm -3 Relatively low water absorption High strength Particle size ranging from ~ 60µm to 2mm

19 Industrial manufacturing process Raw materials (recycled glass) Ball milling As used by Poraver, Liaver and Ecoglass manufacturers Mixing Pan pelletising Sintering (rotary kiln)

20 Laboratory manufacturing process 1. Raw materials Fine glass powder PSA 4. Pelletising Angle and rotation speed adjusted 2. Grinding 1-4 hours 5. Rapid sintering Temp.: 800 C Time: < 40 min 3. Mixing Water 6. Sieving Size: 1 7 mm

21 particle density ( g cm -3 ) Water absorption (wt.%) Effect of PSA content on density and water absorption Wet milled for 1 hour, T sint = 800 C, t sint = 20 minutes Commercial LWFs Commercial LWFs PSA content (wt. %)

22 particle density (g cm -3 ) Effect of sintering time: 20% PSA-80% glass mix 2,0 1,8 1,6 1,4 1,2 1,0 0,8 0,6 Commercial LWF 0,4 0,2 0, Sintering time (min)

23 particle density (g cm -3 ) Effect of sintering time: 20% PSA-80% glass mix 2,0 1,8 1,6 1,4 1,2 1,0 0,8 0,6 0,4 0,2 Heating Glass softening Gas evolution Stable phase Commercial LWF Potential coarsening 0, Sintering time (min)

24 particle density (g cm -3 ) Water absorption (%) Effect of sintering time: 20% PSA -80 % glass mix 2 1,8 1,6 Commercial LWF ,4 1,2 1 0, ,6 0,4 0,2 Commercial LWF Sintering time (min)

25 Effect of sintering time on microstructure Sintering time: 5 minutes Sintering time: 10 minutes

26 Effect of sintering time on microstructure Sintering time: 15 minutes Sintering time: 20 minutes

27 Crushing Strength (10) (MPa) 20% PSA-80% glass mix: Effect of pellet size on CS (10) mm 2-5mm 5-7mm Pellet size 20% PSA_800 C_15min Commercial LWF

28 Conclusions Identified LWFs as the target product cenosphere-type products PSA can be mixed with glass (1:4) to form LWFs Laboratory production process mimics industrial manufacturing Promising results to date: - Light weight fillers are produced at particle sizes ranging from 1-7 mm - Relatively low sintering temperature (800 C) and time (15 min) - Optimum PSA-glass LWFs have higher crushing strength than commercial LWFs

29 Questions and Answers Thank you!