1. Saint-Gobain Vidros S/A
CHARACTERIZATION OF ASHES FROM INCINERATION OF
CHROMIUM-TANNED LEATHER SHAVINGS AND THEIR
APPLICATION AS COLORANT IN SODA-LIME CONTAINER GLASS
Diego Mendes
Marcio Madeira Guimarães
Marcos Henrique Gibim
Samuel Márcio Toffoli
Polytechnic School
University of São Paulo
2. Saint-Gobain Vidros S/A
Polytechnic School
University of São Paulo2
Objective
Verify the possibility of using ashes from leather shavings as
a colorant in soda-lime silicate glass
Characterization of the ashes
O Particle Size Distribution;
O Chemical Analyzis;
O Scanning Electron Microscopy + EDS.
Glass melting
OLaboratory scale;
OChromite and leather shaving ashes;
OSame base glass (target: 0,2 wt% of Cr2O3 in the glass);
Characterization of the glass
O Chemical Analyzis;
O Scanning Electron Microscopy + EDS
3. Saint-Gobain Vidros S/A
Polytechnic School
University of São Paulo3
Introduction
Tanning process
O Skin treated by tannin process;
O Chromium salts – stabilize skin;
O Remaining shavings – environmental impact;
Wet-blue leather
Ashes
Green glass
Calcination
O T ~ 900 ºC;
O Volume reduction;
Ashes as a glass colorant
O Minimize waste disposal;
O Reduce raw material extraction;
O Replace chromite in glass.
4. Saint-Gobain Vidros S/A
Polytechnic School
University of São Paulo4
Experimental
Characterization of the ashes (as received)
O Particle Size Distribution - Laser Scattering;
O Phase analysis - X-Ray Difraction (XRD);
O Chemical Analysis – Wet Analysis and X-Ray Fluorescence (XRF);
O Image observation - Scanning Electron Microscopy - Energy Dispersive Spectroscopy
(SEM-EDS);
Glass Melting
OBase glass: Commercial soda-lime containing either chromite or ashes;
O Alumina crucibles, 1450 °C, 3h;
Characterization of the glasses
O Chemical Analyzis - X-ray Fluorescence (XRF);
O Image observation - (SEM-EDS).
8. Saint-Gobain Vidros S/A
Polytechnic School
University of São Paulo8
Results: Particle Size Distribution
Chromite
Ashes
d (0.1) = 4.6 mm
d (0.5) = 149.5 mm
d (0.5) = 22.4 mm
d (0.1) = 6.6 mm
9. Saint-Gobain Vidros S/A
Polytechnic School
University of São Paulo
Results: Obtained glass
9
Glass with chromite Glass with ashes Glass with chromite Glass with ashes
11. Saint-Gobain Vidros S/A
Polytechnic School
University of São Paulo11
Glass with chromite - Bottom Glass with ashes - Bottom
Glass with chromite - Top Glass with ashes - Top
12. Saint-Gobain Vidros S/A
Polytechnic School
University of São Paulo
Glass with
ashes - Top
(wt%)
Glass with
ashes - Bottom
(wt%)
Glass with
chromite - Top
(wt%)
Glass with
chromite - Bottom
(wt%)
Na2O 11.69 11.85 10.70 10.72 11.70 11.24 11.24 12.06
Al2O3 4.63 4.31 4.98 4.58 4.69 4.78 4.68 4.47
SiO2 72.98 73.20 73.66 74.10 72.32 73.31 72.93 72.00
K2O 0.67 0.63 0.60 0.70 0.75 0.62 0.54 0.75
CaO 9.35 9.37 9.68 9.52 9.95 9.36 10.07 10.09
Cr2O3 0.67 0.65 0.38 0.39 0.58 0.69 0.53 0.63
12
Results: Glass Comparison - EDS
13. Saint-Gobain Vidros S/A
Polytechnic School
University of São Paulo13
Glass comparison - XRF
Glass with
ashes
(wt%)
Glass with
chromite
(wt%)
Target
(wt%)
Na2O 12,5 13,2 13,3
Al2O3 2,04 1,88 1,47
SiO2 73,2 72 73,1
K2O 0,35 0,32 0,32
CaO 11,1 11,8 11,1
Cr2O3 0,19 0,17 0,2
MgO 0,09 0,14 0,08
Fe2O3 0,381 0,322 0,41
TiO2 0,032 0,029 -
SO3 0,2 0,2 -
14. Saint-Gobain Vidros S/A
Polytechnic School
University of São Paulo14
Conclusions
It is possible to use ashes from the calcination of
chromium-tanned leather shavings as an alternative
colorant in soda-lime silicate glass.
15. Saint-Gobain Vidros S/A
Polytechnic School
University of São Paulo15
Challenges
Evaluate fusibility
O High Cr2O3 content in the ashes ~ 70 %;
O Homogeneous fusion;
● Color coordinates;
Cr VI content
O Environmental and labour problems;
O XPS;
O XANES (particle acelerator);
Calcination process
O Optimization, control;
16. Saint-Gobain Vidros S/A
Polytechnic School
University of São Paulo16
Acknowledgments
Alberto Delboni;
Mauro Akerman;
Marcos Gibim;
Paulo Feldbaum.
