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

Saint-Gobain Vidros S/A

Polytechnic School

University of São Paulo 2

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

Saint-Gobain Vidros S/A

Polytechnic School

University of São Paulo 3

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.

Saint-Gobain Vidros S/A

Polytechnic School

University of São Paulo 4

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).

Saint-Gobain Vidros S/A

Polytechnic School

University of São Paulo

Results: Chemical analysis – ashes and chromite

5

Ashes (wt%) Chromite (wt%)

Oxide XRF Wet analysis EDS XRF EDS

Cr2O3 68 68.9 89.01 44.3 41.67

Fe2O3 - - - 16.9 17.40

SiO2 12 - 5.90 5.51 1.32

Al2O3 6.7 - 4.11 17.9 22.72

MgO - - - 17.1 16.69

Na2O 5.3 - - - -

CaO 1.0 - 0.98 0.57 0.20

P2O5 3.6 - - - -

SO3 2.5 - - - -

TiO2 0.8 - - 0.32 -

MnO - - - 0.18 -

Saint-Gobain Vidros S/A

Polytechnic School

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Results: XRD - ashes

6

Pow

er

poin

t te

mpla

te la

nscape

01-1129 (D) - Aluminian Chromite, syn - Fe(Al,Cr)2O4 - Y: 15.82 % - d x by: 1.0000 - WL: 1.54090 - Cubic -

25-0626 (I) - Buetschliite, syn - K2Ca(CO3)2 - Y: 1.74 % - d x by: 1.0000 - WL: 1.54090 - Rhombohedral -

82-0512 (C) - Cristobalite - SiO2 - Y: 7.38 % - d x by: 1.0000 - WL: 1.54090 - Tetragonal - I/Ic PDF 5.3 -

05-0490 (D) - Quartz, low - SiO2 - Y: 3.82 % - d x by: 1.0000 - WL: 1.54090 - Hexagonal - I/Ic PDF 3.6 -

06-0504 (D) - Eskolaite, syn - Cr2O3 - Y: 16.67 % - d x by: 1.0000 - WL: 1.54090 - Rhombohedral - I/Ic PDF 1.8 -

Operations: Import

Marcelo-Eng.Quimica - File: CinzaRG.RAW - Type: 2Th/Th locked - Start: 2.000 ° - End: 72.000 ° - Step: 0.020 ° - Step time: 1.0 s - Temp.: 25 °C (Room) - Time Started: 2 s - 2-Theta: 2.000 ° - Theta: 1.00

0

100

200

300

400

500

600

700

800

900

1000

2-Theta - Scale

2 10 20 30 40 50 60 70

d=

4.0

71 d

=3

.62

8

d=

3.3

46

d=

2.8

62

d=

2.6

62

d=

2.4

77

d=

2.2

62

d=

2.1

73

d=

2.0

45

d=

1.8

14

d=

1.6

70

d=

1.5

78

d=

1.4

64

d=

1.4

31

d=

3.1

61

Eskola

ita

Quart

zo

Cristo

balit

a

Ca

rbonato

de C

álc

io e

Po

tássio

Cro

mita d

e A

lum

ínio

Cr2O3

Saint-Gobain Vidros S/A

Polytechnic School

University of São Paulo 7

Results: SEM (2500 x)

Chromite Ashes

Saint-Gobain Vidros S/A

Polytechnic School

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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

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

Saint-Gobain Vidros S/A

Polytechnic School

University of São Paulo 10

Results: SEM – Chromite vs Ashes

Alumina crucible

Saint-Gobain Vidros S/A

Polytechnic School

University of São Paulo 11

Glass with chromite - Bottom Glass with ashes - Bottom

Glass with chromite - Top Glass with ashes - Top

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

Saint-Gobain Vidros S/A

Polytechnic School

University of São Paulo 13

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 -

Saint-Gobain Vidros S/A

Polytechnic School

University of São Paulo 14

Conclusions

It is possible to use ashes from the calcination of

chromium-tanned leather shavings as an alternative

colorant in soda-lime silicate glass.

Saint-Gobain Vidros S/A

Polytechnic School

University of São Paulo 15

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;

Saint-Gobain Vidros S/A

Polytechnic School

University of São Paulo 16

Acknowledgments

Alberto Delboni;

Mauro Akerman;

Marcos Gibim;

Paulo Feldbaum.