Estimates of the Chemical form of
fluorine in Steel Slag by the
application of saturated column test
Environmental Risk Analysis,
Kyoto University
Kengo NAKAMURA, Minoru YONEDA
1
Back Ground
Steel Slag as Recycled Materials
CaF2
Benefit: low temperature
= low cost = Save energy
Oxidation Slag：70kg/t
Reduction Slag：40kg/t
Fluorine regulated environmental standards in Japan
Recycled Materials
・Building material (Ex. Base course material)
・Cement raw material (Ex. Aggregate)
2
Back Ground
Environmental Standards Relating to use Steel Slag
Fluorine Environmental Standards
Designated standard
Leachate Standard (㎎/L)
Concentration Standard (㎎/kg)
0.8
4000
WHO : 1.5Fmg/L
Ex. Sea : 1.3~1.7Fmg/L
More Strict
The standard of fluorine addition will become trade between
the reduction of energy consumption and human health risk.
3
Purpose
Purpose in this study
• To determined chemical form of
the fluorine that influenced or
indicate the solubility of fluorine
component by.
The method of estimate fluorine compounds is
saturation column test
1. Dissolution fluorine trend from steel slag is
reproduced through column test
2. PHREEQC fluorine compound is determined by
comparing PHREEQC database
4
Method
Sample (Oxidation slag, Reduction slag)
Oxidation slag
O
36.09
Fe
18.81
Ca
15.59
Si
8.69
Al
6.73
Mn
5.29
Mg
3.15
C
1.32
Na
0.38
Ti
0.29
F
0.40
others
3.26
Reduction slag
O
46.85
Ca
29.75
Si
8.71
Al
5.25
Mg
3.84
C
2.55
S
0.71
Mn
0.27
Fe
0.26
Ti
0.20
F
1.17
others
0.44
It is composed mainly of solid phase described above,
quantities evaluation of solid phase in steelmaking slag has
not been achieved.
5
Method
Saturation Column Test
• The saturation column test is a
method to estimate short term
behavior of dissolution of element
in solid recycled materials.
Outflow
Condition
Sample
Oxidation slag
Column height
（cm）
Column bore
（cm）
Solvent
Flow rate
（mL/min）
Fill ration(g)
Water content
rate（%）
Fill ration
（Dry）（g）
Acryl Column
Reducing slag
Filter
30
5
Ultra pure water
19.6
1264.39
699.96
0.06
2.8
1263.63
680.38
Density（g/ml）
3.96
3.2
Filling amount
(Dry)（ml）
319.1
212.62
Porosity（%）
45.83
63.9
Inflow
The final condition of column
test will be achieved if the
composition of Liquid
(Solvent in liter) : solid (steel
slag in kg) = 10 :1
6
Result
Oxidation Slag
Results of Column Test
F Concentration : 3.6mg/L
pH:10.4
F Concentration : 0.2mg/L
pH:10.4
Reduction Slag
F Concentration : 2.2mg/L
pH:11.6
F Concentration : 0.6mg/L
pH:11.5
Decrease of dissolution
fluorine compounds, fluorine
phase is transformed from
high solubility phase to low
solubility phase.
Fluorine compounds are
possible that it is seen not
change due to the
migration of solubility by
water flow.
7
Result
Chemical Equilibrium Model PHREEQC
• Geosphere transition model PHREEQC is used to
calculate an ionic transfer as surface of aqueous
and solid phase. Inorganic thermodynamic model
in PHREEQC has been taken into account solid
phase in the transition between the dissolution
as well as an action of ion.
Example
Dissolution of the mineral fluorine(CaF2)
CaF2 ↔ Ca2+ + 2F－
At equilibrium the aqueous concentrations obey the
solubility product:
Kfluorite = [Ca2+][F-]2 = 10-10.57 at 25℃
Relation can be rewritten in logarithmic form as:
logKfluorite = log[Ca2+] + log[F-]2 = -10.57
8
Result
Fluorine Components
Fluorine component on the
surface of steel slag
≡ 𝐴𝑙𝐹3 → 𝐴𝑙 3+ + 3𝐹 −
≡ 𝐶𝑎𝐹2 → 𝐶𝑎2+ + 2𝐹 −
≡ 𝐹𝑒𝐹2 → 𝐹𝑒 2+ + 2𝐹 −
≡ 𝑀𝑔𝐹2 → 𝐹𝑒 2+ + 2𝐹 −
≡ 𝐹𝑒𝐹3 → 𝐹𝑒 3+ + 3𝐹 −
≡ 𝑁𝑎𝐹 → 𝑁𝑎+ + 𝐹 −
Name
Reaction
logK
deltaH(kJ)
AlF3
Fluorite(CaF2)
FeF2
FeF3
Sellaite(MgF2)
NaF
AlF3 = Al+3 + 3FCaF2 = Ca+2 + 2FFeF2 = 2F- + Fe+2
FeF3 = 3F- + Fe+3
MgF2 = 2F- + Mg+2
NaF = Na+ + F-
-17.21
-10.04
-2.38
-19.24
-9.38
-0.021
-34.04
12.13
-51.69
-13.81
-12.46
-569
Relationship pH and pe of fluorine
compounds are created using PHREEQC
Calculation condition
Fluorine compounds are presented 0.1mol/kg and
reappearance dissolution fluorine concentration on
water 1L (density of water: 1g/cm3)
9
Result
Chemical Property of Fluorine Components
pH dependence
CaF2, MgF2, FeF3 are showed
pH dependence.
pe dependence
Fluorine compounds are not
showed pe dependence except
FeF3.
In order to reproduce the fluorine trend in the column test, solvent conditions are
used to measure the value of pH which was obtained from column test and
chemical equilibrium computation.
10
Result
Estimate of fluorine in steel slag by PHREEQC
for calculating fluorine compounds
Parameter of column test are set at the same condition with PHREEQC
(flowing amount water, water flow time, column height, sample density)
Each fluorine compound was calculated in each column. Fluorine compounds are
assumed to present each fluorine compounds 100% in column
Oxidation Slag
AlF3, CaF2, FeF2, FeF3, MgF2, NaF (6 column)
Reduction Slag
AlF3, CaF2, MgF2 (3 column)
It is assumed that liquid solution condition is
used same pH parameter of column test
(Oxidation slag: max pH10.4, Reduction slag: max pH11.8)
11
Result
Estimate fluorine in steel slag by PHREEQC
Oxidation Slag
Reduction Slag
12
Conclusion
Conclusion
Oxidation Slag
• Base on column test it can be conclude that fluorine
concentration is high in initial condition which was rate
of liquid : solid is 1 :1.
• In addition, from PHREQCE simulation (the relationship
between dissolution concentration and fluorine
dissolution rate) , it suggest that fluorine chemical
compounds of oxidation slag are ALF3 and NaF .
Reduction Slag
• The decreased of fluorine concentration in reduction
slag was lower compare with the decreased of fluorine
concentration in oxidation slag.
• From PHREEQC simulation it can be showed that the
chemical compound of fluorine in reduction slag is AlF3.
13
Thank you for your attention.
14
Result
15
鉄鋼スラグ Iron slag
16
生産量と利用量：Amount of production & utilization
14000
14107 13722
12168 12302
13427 13865
12916
14400
1800
1600
(t)
12000
1400
10000
1200
8000
1000
6000
800
4000
347
385
374
361
392
317
342
452
200
0
0
2000
2001
2002
2003 2004
year
amount of production (Right)
ｺﾝｸﾘｰﾄ 加工用 他利用 埋立等
骨材 原料 3,0%
2,3%
0,3% 2,4%
再使用
17,3%
土木
35,6%
製鋼スラグ
道路
29,5%
地盤改
良材
5,2%
再使用
21,0%
5,2%
2006
2007
amount of recycle (Left)
加工用 他利用
原料
4,0%
11,5%
埋立等
8,8%
ｺﾝｸﾘｰﾄ
骨材
1,3%
再使用
1,6%
道路
39,4%
セメント
1,0%
土木
37,3%
道路
27,1%
地盤改良
材
転炉スラグ 5,5%
2005
Produce and recycle amount of steel slag
*left: produce amount arbor right: recycle amount arbor
加工用原
他利用 埋立等
料
2,8% 0,8%
ｺﾝｸﾘｰﾄ骨
0,3%
材
0,0% セメント
セメント
4,4%
600
400
2000
Final waste disposal amount of accessory product
2000
(t)
16000
土木
28,5%
電気炉スラグ
地盤改
良材
3,9%17
Method
Saturation Column Test
Oxidation
slag
Colume
height（cm）
Colume bore
（cm）
Solvent
Flow rate
（mL/min）
Fill ration(g)
Water content
rate（%）
Fill ration
（Dry）（g）
Density
（g/ml）
Filling
amount
(Dry)（ml）
Porosity（%）
Reducing slag
30
5
Ultra pure water
19.6
1264.39
699.96
0.06
2.8
1263.63
680.38
3.96
3.2
319.1
212.62
45.83
63.9
18