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FUSIONS – HOW TO IMPROVE THROUGHPUT AND
CONCENTRATION RANGE OF ANALYSIS BY ELIMINATING
THE LOSS ON IGNITION PROCESS STEP, USING DIFFERENT
DILUTION RATIOS AND MAINTAINING ACCURACY AND
PRECISION OF RESULTS
Laura Oelofse (Rigaku Americas) and Yoshijuro Yamada (Rigaku
Corporation )
Abstract
The use of fusions for XRF in industrial process monitoring is common
practice and there are several time consuming steps to complete in
order to render a sample fusion ready.
This paper details a method that would eliminate the need to carry out
the Loss on Ignition, Gain on Ignition step thus eliminating 2 hrs from
the preparation time and it also details the ability to use different
dilution ratios of sample and flux for materials on the same calibration
curve in order to increase the scope of materials that can be included in
a universal calibration curve using both naturally sourced certified
reference materials and synthetic pure chemicals as calibration
standards
Analysis Schemes in Various
Industry Sectors
Composition
varies in
narrow range
Widely
varying
composition
Incoming Raw
Materials
Product
XRFs Role in High Throughput
Solutions
Results
Analysis
Sample
Introduction
Sample
Preparation
Sample
Loading
Fusions – Flux + Sample
All compounds changed to oxide form
Eliminate Particle Size Effect
Eliminate Mineralogical Effect
Some Typical Fused Glass Beads
6
Why Preparation of Fused Glass Beads
• Particle size and mineralogical effects are removed or diminished
by fusion of the sample with a suitable flux to form a glass bead.
• Synthetic calibration standards can be made by mixing pure oxides
at concentration levels to suit the analytical range.
• Depending on sample type, fusion can even be quicker than
pressed powder procedure.
• Generally accuracies and reproducibility are superior with fusion
procedure.
• Only drawback is possible dilution of trace elements and therefore
inferior LLD. Low dilution fusions are possible.
7
Preparation of
Fused Glass Beads
Melting method
Heat for
Melting
Weigh out
and mix
Flux + Specimen
Cast & Cool
1000° -1100° C
To standard holder
Glass disk
specimen
Platinum crucible
Remove bubbles
9499D00500
3 - 7 mins
8 - 15 mins
5 mins
8
Preparation of Fused Glass Beads
• Preparation of powder as fused glass bead involves weighing out
sample and flux, placing in Gold/Platinum crucible, heating to 1000
– 1200 degrees and casting as a flat glass bead by pouring melt
into a heated Gold/Platinum mould and cooling under controlled
conditions.
• Newer alternative is moldable where melt remains in crucible and
bead is formed in situ.
• DEPENDING ON NATURE OF SAMPLE – LOSS ON IGNITION
MAY BE NECESSARY. ( CEMENTS, LIMESTONE, DOLEMITE)
9
In reality there are three types of samples
Type 1 – Sample is stable, no loss or gain during fusion process
Sample
Flux
F
S
Type 2 : Sample loses CO2 or Intrinsic Waters during fusion, known as Loss on Ignition
LOI
Sample
Flux
F
S
Type 3: Sample loses CO2 or Intrinsic Waters during fusion, known as LOI and changes oxidation state and
pick up oxygen, gaining on ignition, known as GOI
LOI
Sample
S
Flux
Replaced with flux
B
GOI
Analytical Error Factors in Fusion Method
The errors can be removed by Rigaku Bead Correction method
Powder Sample
Heterogeneity Effect
Grain-size Effect
Mineralogical Effect
Fusion Bead
Weighing Error
Loss on Ignition
Gain on Ignition
Evaporation of Flux
Error factors
for Bead
Error Factors in Fusion Method
Fusing
Weighing
Weighing error(1)
GOI (3)
O2
Sample
FeO
Flux(Li2B4O7 etc)
Bead
(4)
Flux
LOI
evaporation
(2)
CO2 H O
2
Fe2O3
Pt crucible
1000-1200˚ C
The four error factors can be corrected.
Strategy for the Corrections of LOI, GOI and Dilution Ratio
Model 1 : Use of Ratio of flux to sample weight ( F/S)
LOI
Sample
Flux
F
S
Definition of LOI
: Imaginary component with no x-ray absorption
Correction LOI(GOI) : Concentration is manually input or calculated as balance
Dilution ratio : Corrected by manual input of F/S
Model 2 : Use of Ratio of bead to sample weight( B/S)
LOI
Sample
S
Flux
Replaced with flux
B
Definition of LOI
: Imaginary component of flux
Correction : LOI(GOI) : Concentration is manually input or calculated as balance
Dilution ratio : Corrected by manual input of B/S
(Note) Flux evaporation can be corrected
Analysis in Fused Beads
Use of fusion bead correction
Software generates theoretical alphas for LOI/GOI and dilution ratio
Calibration equation
Wi  (aI 2  bI  C)(1  K   αjWj  αLOIWLOI  αFRF)
The alphas correct for
LOI/GOI
Dilution ratio
and Flux evaporation during fusing
The alphas are generated by using a fundamental parameter software and it
generates variety of models.
Dilution ratio models : Flux weight to sample
weight(F/S) or bead weight to sample weight(B/S)
LOI/GOI : Loss eliminated or manual input
Rigaku Fusion Bead Correction Software
• Allows for varying flux : sample ratios and the use of
catch weights
• Allows calculation of the Loss on Ignition /Gain on
Ignition and flux loss component by balance or ratio input
BCS376
LOI 0
LOI 10
SiO2
67.1
67.42
60.68
TiO2
0.02
0.02
0.02
Al2O3
17.7
17.79
16.01
Fe2O3
0.10
0.10
0.09
CaO
0.54
0.54
0.49
MgO
0.03
0.03
0.03
Na2O
2.83
2.84
2.56
K2O
11.2
11.25
10.13
LOI
0.35
0.00
10.00
Total
99.87
99.99
100.01
Sample (g)
0.3000
0.2700
Li2B4O7 ( g)
3.0000
3.0000
60
50
40
LOI XRF
Oxides
30
LOI CHEM
Lineær (LOI CHEM)
20
10
0
0
20
LOI CHEM
-10
40
60
Fusion Bead Correction for LOI in Various Kinds of Materials
BCS393
(Limestone)
Chem.
XRF
Diff.
NBS69b
Chem
(Bauxite)
XRF
Diff.
NBS697
Chem
(Bauxite)
XRF
Diff.
NBS97a
Chem
(Clay)
XRF
Diff.
JDo 1
Chem
(Dolomite)
XRF
Diff.
BCS375
Chem
(Feldspar)
XRF
Diff.
R801
Chem
(Pyrophyllite) XRF
Diff.
BCS314
Chem
(Silica brick) XRF
Diff.
SiO2 TiO2 Al2O3 Fe2O3 MnO MgO
0.70 0.01
0.12
0.05 0.01
0.15
0.77 0.02
0.16
0.03 0.00
0.13
-0.07 0.01
0.04 -0.02 -0.01 -0.02
13.57 1.92 49.29
7.21 0.11
0.09
13.68 1.92 49.28
7.25 0.11
0.14
0.11 0.00
-0.01
0.04 0.00
0.05
6.84 2.53 45.99 20.09 0.41
0.18
6.88 2.51 45.98 20.15 0.42
0.25
0.04 -0.02
-0.01
0.06 0.01
0.07
44.00 1.91 39.06
0.45 0.00
0.15
43.89 1.93 38.72
0.45 0.00
0.09
-0.11 0.02
-0.34
0.00 0.00 -0.06
0.21 0.00
0.01
0.02 0.01 18.58
0.28 0.01
0.06
0.01 0.00 18.87
0.07 0.01
0.05 -0.01 -0.01
0.29
67.15 0.38 19.82
0.12 0.00
0.05
67.80 0.38 20.05
0.10 0.00
0.07
0.65 0.00
0.23
0.02 0.00
0.02
78.64 0.10 16.76
0.17 0.00
0.04
78.62 0.10 16.71
0.17 0.00
0.08
-0.02 0.00
-0.05
0.00 0.00
0.04
96.40 0.19
0.77
0.53 0.01
1.81
96.47 0.20
0.79
0.49 0.00
1.86
0.07 0.01
0.02 -0.04 -0.01
0.05
CaO Na2O
55.46 0.03
55.78 0.00
0.32 -0.03
0.13 0.03
0.17 0.00
0.04 -0.03
0.71 0.04
0.78 0.00
0.07 -0.04
0.11 0.04
0.13 0.01
0.02 -0.03
33.94 0.01
33.95 0.00
0.01 -0.01
0.89 10.41
0.87 9.95
-0.02 -0.46
0.04 0.22
0.08 0.16
0.04 -0.06
1.81 0.05
1.86 0.01
0.05 -0.04
K2O
0.02
0.01
-0.01
0.07
0.07
0.00
0.06
0.06
0.00
0.50
0.58
0.08
0.00
0.00
0.00
0.79
0.74
-0.05
0.18
0.19
0.01
0.09
0.08
-0.01
P2O5
0.01
0.00
-0.01
0.12
0.11
-0.01
0.97
0.97
0.00
0.36
0.37
0.01
0.04
0.03
-0.01
0.00
0.01
0.01
0.00
0.02
0.02
0.00
0.01
0.01
LOI
43.44
43.10
-0.34
27.46
26.99
-0.47
22.18
22.00
-0.18
13.42
13.83
0.41
47.18
46.79
-0.39
0.39
0.03
-0.36
3.86
3.88
0.02
0.10
0.01
-0.09
Results are obtained by using theoretical alphas and LOIs are
obtained as balance. The accuracy of the calculated LOI across the
range of 0 % - 50% is 0.5%
Quantification and
Correction of Gain
on Ignition
Synthetic mixtures of SiO2 and
FeO were blended to yield
30%, 50% and 70% FeO
During fusion the FeO is
oxidized to Fe2O3 and there is
a weight gain of
(Fe2O3 – 2FeO)/ 2FeO
The mass absorption
coefficient of GOI is set to zero
and the value is considered as
a negative LOI in the FP
calculation.
The WFe2O3 = WFeO + W GOI
SiO2
FeO
calc.
Recalc.
FP value
70.00
30.00
calc.
Recalc.
FP value
50.00
calc.
Recalc.
FP value
30.00
Fe2O3
32.27
32.48
50.00
52.64
52.84
70.00
72.17
72.15
Determination of GOI from Standard Iron Ore
Fe2O3
Diff
Chem
XRF
JSS 803-2
89.57
89.71
0.14
JSS830-3
84.18
84.16
-0.02
Euro 680-1
86.33
86.31
-0.02
ASCRM 004
89.43
89.51
0.08
• Method applied to iron ore with high Fe content and
shown to be suitable
Dilution Ratio Correction
STD
S:F 1:5
JB-2
UNK
S:F 1:10
JG-1
Lit.
FP
Lit.
SiO2
52.83
73.06
72.75
TiO2
1.18
0.28
0.26
Al2O3
14.57
14.02
14.29
Fe2O3
14.24
2.13
2.21
MnO
0.20
0.06
0.06
MgO
4.63
0.71
0.75
CaO
9.82
2.18
2.19
Na2O
2.02
3.38
3.41
K2O
0.43
4.10
3.97
P2O5
0.10
0.09
0.10
Application of LOI, GOI and dilution ratio correction to
Empirical Calibration Methods
• Matrix correction coefficients were theoretically calculated for LOI,
GOI and dilution ratio correction components
• The matrix correction expression including the dilution ratio
correction is shown on the next slide
• Using the Theoretical Alpha Correction model where the base
component is considered to be the LOI/GOI/D.C then these are
eliminated in the De Jongh calculation and are calculated as a
balance component.
• The accuracy for Fe2O3 in a regression of geological standards for
an uncorrected calibration was 0.161%, for a calibration with
conventional matrix corrections 0.066% and for theoretical matrix
correction coefficients with LOI and GOI correction an improved
accuracy of 0.056%
Rigaku Theoretical Alphas for Fusion Bead
Correction equation of T.Fe
Wi = (aiIi2+biIi +c)*(1+SajWj + aFRF - KF)
Factor Coefficient
K
0.910900
a(T.Fe) 0.002392
a( SiO2) 0.001413
a(Mn)
0.002923
a(CaO) 0.006793
a(MgO) 0.000967
a(Al2O3) 0.001128
a(TiO2) 0.006700
a(P)
0.003929
a(S)
0.004874
a(K)
0.008125
a(FLUX) 0.089130
1. The correction coefficients a j for inter-elements and flux
are calculated theoretically by Rigaku/FP software. These
alphas depend on the optics of spectrometer.
2. K corresponds to the standard dilution ratio.
3. When the actual dilution ratio “ RF” ( Bead weight/ sample
weight ) is input for the each sample manually, all error
factors are automatically corrected. ( LOI, GOI and Dilution
Correction)
4. Calibration constants (a,b,c) are calculated using the nonlinear regression equation , after standard samples are
measured.
Dilution Ratio Correction
Calibration equation with dilution ratio correction
Wi  b I i  c 1   a j Wj  a F R F  K F 
 j L

K F   aFR F
General calibration equation
Wi  b I i  c 1   a j Wj  a F R F 


R F  R F  R F
aFRF + KF is the correction term for
the difference between the actual and
standard dilution ratio.
RF : Difference between the actual
and standard ratio
RF
: Actual dilution ratio
Matrix Correction Model
Correction model
Lachance-Traill
Uncorrected
component
Analyte
Notes
Correction by all the components except the
analyte.
The calibration curve is linear.
de Jongh
Base component
Correction by all the elements except the base
component.
The calibration curve is linear.
JIS
Base component
and analyte
Correction by all the elements except the base
component and the analyte.
The calibration curve is linear or quadratic.
When a significant amount of LOI (GOI) is contained, it is advisable to use de Jongh or JIS
model.
SiO2 Calibration Curve
Analysis sample: rock fusion disk (dilution ratio 5:1)
de Jongh model
X-ray intensity (a. u.)
X-ray intensity (a. u.)
JIS model
Accuracy: 0.18
mass%
Standard value (mass%)
Accuracy: 0.17
mass%
Standard value (mass%)
considering self-absorption
by the analyte
CaO Calibration Curve
Analysis sample: rock fusion disk (dilution ratio 5:1)
de Jongh model
X-ray intensity (a. u.)
X-ray intensity (a. u.)
JIS model
Accuracy: 0.17 mass%
Standard value (mass%)
Accuracy: 0.14 mass%
Standard value (mass%)
considering self-absorption
by the analyte
Comparison of Matrix
Correction Coefficients
between Several Materials by
the Fusion Method
— Analysis of Refractories —
Calibration Range of the Major Components and
Dilution Ratio for Each Material
Material
Major component (mass%)
SiO2
Al2O3
Fe2O3
MgO
6–49
Silica
84–97
–10
10
–44
47–94
10
81–99
Chrome-magnesia
–27
Zircon-zirconia
–45
Alumina-zirconia-silica
–42
Alumina-magnesia
The whole range
–1
(Flux/Sample)
37–86
Magnesia
–1
ZrO2
Clay
High alumina
–5
Cr2O3
Dilution ratio
10
2–53
10–82
10–93
–97
10–52
–94
22.16
48–92
10
12–48
10
3–79
–27
–99
• Wide calibration range
• Different dilution ratio
10
10
–53
–92
10–22.16
• Flux: Li2B4O7
• LiNO3 was used just
for Chrome-magnesia.
Comparison of Matrix Correction
Coefficients for Each Material (1)
Clay
Alumina-Zircon-Silica
SiO2
Analyte
Correcting comp.
Al2O3
Fe2O3
TiO2
MnO
CaO
MgO
Na2O
K2O
P2O5
Cr2O3
ZrO2
High alumina
1.38E-03
1.02E-03
2.44E-04
8.65E-04
6.91E-05
1.33E-03
1.04E-03
-5.41E-05
-1.88E-05
6.06E-04
8.76E-04
Si-Ka
1.38E-03
1.01E-03
2.41E-04
8.62E-04
6.60E-05
1.33E-03
1.04E-03
-5.75E-05
1.37E-03
1.02E-03
2.43E-04
6.81E-05
1.33E-03
1.04E-03
-5.49E-05
6.07E-04
8.68E-04
Correction model: Lachance-Traill
Correction coefficients are almost identical for each
material.
SiO2 Calibration Curve
Magnified
Magnesi
a
X-ray intensity (a. u.)
X-ray intensity (a. u.)
Accuracy:
0.25 mass%
Silica
Clay
AZS
AZS
◆ 10 : 1
◆ 22.16 : 1
Chrome-magnesia
(Chrome-magnesia)
Standard value (mass%)
Standard value (mass%)
AZS: Alumina-zirconia-silica
Comparison of Matrix Correction
Coefficients for Each Material (2)
Clay
Alumina-Zircon-Silica
Fe2O3
Analyte
Correcting comp.
SiO2
Al2O3
TiO2
MnO
CaO
MgO
Na2O
K2O
P2O5
Cr2O3
ZrO2
High alumina
-1.88E-03
-2.19E-03
3.93E-03
-1.94E-04
4.03E-03
-2.37E-03
-2.62E-03
3.94E-03
-1.65E-03
7.27E-03
1.09E-03
Fe-Ka
-1.87E-03
-2.18E-03
3.95E-03
-1.93E-04
4.04E-03
-2.36E-03
-2.61E-03
3.96E-03
-2.06E-03
-2.37E-03
3.64E-03
3.72E-03
-2.54E-03
-2.79E-03
3.64E-03
6.91E-03
1.30E-03
Correction model: Lachance-Traill
Correction coefficients are almost identical for each
material.
Fe2O3 Calibration Curve
Magnified
Chrome-magnesia
Accuracy:
0.029
mass%
◆ 10 : 1
X-ray intensity (a. u.)
X-ray intensity (a. u.)
Magnesi
a
Chrome-magnesia
◆ 22.16 : 1
Zircon-zirconia
(Chrome-magnesia)
Standard value (mass%)
Standard value (mass%)
AZS: Alumina-zirconia-silica
Dilution Ratio Correction
+ Matrix Correction
Rock sample
Analyte
GSJ:
:
dilution ratio 10:1 and 5:1
: SiO2
Analysis sample
CCRMP: SY-2, SY-3
JA1, JA2, JA3, JB2, JB3, JG1a, JG2, JG3, JGb1, JR1, JR2, JLs1, JCp1
Dilution Ratio Correction
Rock sample
Analyte
:
dilution ratio 10:1 and 5:1
: SiO2
No correction
X-ray intensity (a. u.)
X-ray intensity (a. u.)
Accuracy: 11 mass%
●：5:1
●：10:1
Standard value (mass%)
Dilution ratio
correction
Accuracy: 3.6
mass%
●：5:1
●：10:1
Standard value (mass%)
The dilution ratio correction improves
the accuracy; however, the fitting is
still not excellent due to matrix effect.
Dilution Ratio Correction
+ Matrix Correction
Dilution ratio
correction
Accuracy: 3.6
mass%
● 5:1
● 10:1
Standard value (mass%)
:
dilution ratio 10:1 and 5:1
: SiO2
X-ray intensity (a. u.)
X-ray intensity (a. u.)
Rock sample
Analyte
Dilution ratio
cor.
+ Matrix cor.
Accuracy:
0.33 mass%
● 5:1
● 10:1
Standard value (mass%)
The combination of the dilution
ratio and matrix corrections enables
an excellent fitting.
LOI Correction (1)
• Test sample: rock sample with 50 mass% LOI
(the bead was made with the dilution ratio
10:1, and then treated as the dilution ratio 5:1,
which results in the sample with 50 mass%
LOI.)
• Analyte: SiO2
LOI Correction and
Matrix Correction Coefficients
Correction model: de Jongh
Element line: Si-Ka
Without LOI cor.
With LOI cor.
Base component
SiO2
LOI
Na2O
MgO
Al2O3
SiO2
P2O5
K2O
CaO
TiO2
MnO
Fe2O3
-4.79E-04
-6.32E-05
5.15E-03
5.81E-03
5.91E-03
2.78E-03
2.74E-03
2.67E-03
2.94E-03
3.35E-03
4.76E-03
5.11E-03
-1.97E-03
-1.99E-03
-2.03E-03
-1.87E-03
-1.61E-03
-7.21E-04
5.03E-04
Matrix Correction
(without LOI Correction)
Analyte
: SiO2
Accuracy: 2.5
mass%
● w/o LOI
● with LOI
Standard value (mass%)
X-ray intensity (a. u.)
X-ray intensity (a. u.)
No correction
Matrix
correction
Accuracy: 3.5 mass%
● w/o LOI
● with LOI
Standard value (mass%)
LOI Correction and Matrix
Correction
Matrix
correction
Accuracy: 3.5 mass%
● w/o LOI
● with LOI
Standard value (mass%)
: SiO2
X-ray intensity (a. u.)
X-ray intensity (a. u.)
Analyte
LOI correction
+ Matrix cor.
Accuracy:
0.26 mass%
● w/o LOI
● with LOI
Standard value (mass%)
Wide Analysis Range in XRF
Analysis of Diverse Natural
Minerals
by the Fusion Method
(Synthetic Fusion Bead Added)
Purpose of This Test Analysis
• To obtain a good fitting for calibration curves with wide
concentration range of diverse natural minerals by the fusion
method
• To obtain a good fitting for calibration curves with synthetic
standard fused beads
Reference Materials for Calibration (1)
Sample
Material
Dil. ratio
Sample
Material
Dil. ratio
BAS203a
Talc
10
NBS688
Basalt rock
10
BCS313-1
High purity silica
10
SRM 1c
Limestone
10
BCS314
Silica brick
10
SRM 69b-1
Bauxite
10
BCS315
Fire brick
10
SRM 696
Bauxite Surinam
10
BCS319
Magnesite
10
SRM 697
Bauxite Dominican
10
BCS368
Dolomite
10
SRM 698
Bauxite Jamaican
10
BCS369
Magnesite-Chrome
22.167
SRM 70a
Potash feldspar
10
BCS370
Magnesite-chrome
22.167
SRM 99a
Soda feldspar
10
BCS375
Soda feldspar
10
R-603
Clay
10
BCS376_1
Potash feldspar
10
R-701
Feldspar
10
BCS358
Zirconia
10
R-801
Pyrophyllite
10
BCS388
Zircon
10
JSS009-2
Pure iron oxide
10
BCS389
High purity magnesium
10
JRRM511
Chrome-magnesia
22.167
BCS393
Limestone
10
JRRM602
Zirconia
10
BCS394
Calcined bauxite
10
JRRM701
AZS
10
BCS395
Bauxite
10
RM-611
Portland cement
10
NBS98a
Plastic clay
10
RM-612
Portland cement
10
NBS120c
Florida phosphate rock
10
RM-613
Portland cement
10
Reference Materials for Calibration (2)
Sample
Material
Dil. ratio
Notes
ECISS782-1
Dolomite
10
ECISS776-1
Fire brick
10
BCS348
Ball clay
10
NIST 81a
Glass sand
10
NIST 278_1
Obsidian rock
10
NIST 1413
Glass sand
10
NBS694
Phosphate rock
10
BAS 683-1-(1)
Iron ore sinter
10.13
BAS 683-1-(2)
Iron ore sinter
10.13
BCS315_Co1
Fire brick with Co AA standard sol.
10
For analysis of Co from the WC container
BCS315_W1
Fire brick with W AA standard sol.
10
For analysis of W from the WC container
NIST278_1_Co05
Obsidian rock with Co AA standard sol.
10
For analysis of Co from the WC container
NIST278_1_W05
Obsidian rock with W AA standard sol.
10
For analysis of W from the WC container
TiO2_10
TiO2 reagent
10
To extend TiO2 calibration range
P2O5_25
LiPO3 reagent
10
To extend P2O5 calibration range
K2O_50
K2CO3 reagent
10
To extend K2O calibration range
CaO_100
CaCO3 reagent
10
To extend CaO calibration range
Na2O_25
Na2CO3 reagent
10
To extend Na2O calibration range
Calibration Range
Unit: mass%
Analyte
Calibration range
Analyte
Calibration range
Na2O
0
– 25
Fe2O3
0
– 99.84
MgO
0
– 96.7
Cr2O3
0
– 52.51
Al2O3
0
– 88.8
ZrO2
0
– 92.7
SiO2
0
– 99.78
HfO2
0
– 1.63
P2O5
0
– 33.34
SO3
0
– 6.07
K2O
0
– 50
SrO
0
– 0.28
CaO
0
– 100
Co2O3
0
– 1.407
TiO2
0
– 10
WO3
0
– 1.261
MnO
0
– 0.596
Li2B4O7
10
– 22.167
Dilution ratio
(flux/sample)
Na2O calibration
MgO calibration
Na2CO3
Synthetic bead
Accuracy: 0.048 mass%
Standard value (mass%)
X-ray intensity (a. u.)
X-ray intensity (a. u.)
Accuracy: 0.40 mass%
BCS370
Mg-Cr
BCS369
Mg-Cr
Standard value (mass%)
SiO2 calibration
X-ray intensity (a. u.)
X-ray intensity (a. u.)
Al2O3 calibration
Accuracy: 0.23 mass%
Standard value (mass%)
Accuracy: 0.35 mass%
Standard value (mass%)
P2O5 calibration
SO3 calibration
Phosphat
e rock
Accuracy: 0.017 mass%
Standard value (mass%)
X-ray intensity (a. u.)
X-ray intensity (a. u.)
LiPO3
Synthetic bead
Portland
cement
Accuracy: 0.056 mass%
Standard value (mass%)
K2O calibration
CaO calibration
CaCO3
Synthetic bead
X-ray intensity (a. u.)
X-ray intensity (a. u.)
K2CO3
Synthetic bead
Accuracy: 0.021 mass%
Standard value (mass%)
Accuracy: 0.27 mass%
Standard value (mass%)
TiO2 calibration
Fe2O3 calibration
Fe2O3
Synthetic bead
X-ray intensity (a. u.)
X-ray intensity (a. u.)
TiO2
Synthetic bead
Accuracy: 0.027 mass%
Standard value (mass%)
Iron ore
Accuracy: 0.067
mass%
Standard value (mass%)
Summary
• By applying the dilution ratio correction, LOI correction and matrix
correction (theoretical alphas), it is possible to obtain a good fitting for
calibration curves with wide concentration range for diverse natural rocks
and minerals by the fusion method.
• With a few calibration standards, it is necessary to use the de Jongh or
Lachance-Traill models, where calibration curves are linear in theory. In this
test, de Jongh model was used because some samples contain significant
LOI content.
• With a large number of calibration standards, it is possible to use the JIS
model, where calibration curves can be quadratic.
• With synthetic fused beads to extend the calibration range, it is possible to
obtain a good fitting for calibration curves.
Conclusion
• The fusion bead method is useful sample preparation for eliminating
hetrogeneity effects, particle size effects, however chemical
reactions can cause the sample weight to decrease or/and increase
during fusion because of volatilization of H2O, CO2 and oxidation.
• It is possible to correct error factors in fusion for either the FP
method or the Empirical Calibration method.
• It is possible to skip the lengthy independent LOI step in preparing
the samples for fusion, by incorporating the step into the fusion
process and correcting for the associated losses and/or gains via
the correction methods just detailed
• It is possible to weigh catch weights and have them recorded in the
dilution correction.
• The time savings realized by eliminating the LOI step and supporting
varying dilution ratios improves throughput and cuts the analysis
cost per sample
• Thank you for your attention