Pyro Processing

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1 00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 100 80 60 40 20 _Quartz masses % Cristob. 200 400 600 800 1000 1200 1400 Fe2O3 C2(A,F) C12A7 C4AF C3A 100 80 60 40 20 clays Clays Ca CO3 CaO CO2 H₂O T °C C₂S 3 C3S 0 Quartz α _β Liqu. 3.1 Evaporation Zone

• Between 100 and 400ºC: H₂O (l) + heat→ H₂O (g),∆H = 44.2 kJ/mol

3.2 Dehydration Zone

Between 350ºC and 650ºC

• Clay starts to lose its water of crystallization:

O H 2 O Al . SiO 2 Heat O H 2 . O Al . SiO 2 ₂ ₂ ₃ ₂ → ₂ ₂ ₃ + ₂ ,∆H =+ 202kJ/mol At 400ºC

• Magnesium carbonate’s decomposition pressure reaches atmospheric pressure at this temperature: 2

3 Heat MgO CO

MgCO + → + ,∆H = +117 kJ/mol

• Vaporization and oxidation of organic compounds and sulfides: 3 3 2 2 2 O Fe O 4SO 2 7 FeS 2 + → + At 550ºC

• CaCO₃starts to decompose at this temperature. However, acidic environment favours the deformation of the molecules of CaCO₃.

3.3 Decarbonation Zone

At 900ºC

• This is the zone where CaCO₃decomposes rapidly into CaO and CO₂because of its decomposition pressure at this temperature:

2

3 CaO CO

CaCO → + ,∆H =+ 178.2kJ/mol

• Much free lime is produced and starts to react: 2 2 2CaO . SiO SiO CaO 2 + → ,∆H =-125.9kJ/mol 3 2 3 2O 2CaO . Al O Al CaO 2 + → ,

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3 2 3 2O 2CaO . Fe O Fe CaO 2 + → ,∆H = -31 kJ/mol

• Free CaO combines with SO₃to give anhydrite: 4

3 CaSO

SO

CaO + →

• This anhydrite reacts with the alkalies from clay to give alkali sulphates: 4 2 2 4 Na O CaO Na SO CaSO + → + SO Na . SO K 3 or SO K CaO O K CaSO₄ + ₂ → + ₂ ₄ ₂ ₄ ₂

• The quantity of SO₃is generally insufficient to combine with the alkalies: 3 8 3 2O C A NaC A Na + → K₂O + C₂S → KC₂₃S₁₂ 3.4 Clinkering Zone At 1200ºC

• Belite(

C

₂

S

)formation completed:

2 CaO

+

SiO

₂

→

2 CaO

.

SiO

₂,∆H = -125.9 kJ/mol.

7 12A

C becomes enriched in lime and changes toC₃A

A

C

₂ and

C

₂

F

form a solid solution : C₄AF ,∆H = -50.4 kJ/mol Between 1250ºC and 1450ºC

• C₃A and C₄AF liquefy and constitute the flux.C₂S combines with freeCaO to form C₃S in the presence of flux, forming nodules: CaO+C₂S →C₃S,∆H =+8 kJ/mol.

• The alkali sulfates decompose, liberating alkalies and

SO

₂: ↑ + ↑ + → + ₂ ₂ ₂ 4 2SO Heat R O SO 1/2 O R

• Anhydrite decomposes intoCaO and

SO

₂: ↑ + ↑ + → + 2 2 4 Heat CaO SO 1/2O CaSO ,∆H = +490 kJ/mol.

• Ferric oxide, in a reducing atmosphere, changes to ferrous oxide: ↑ + → ₂ 2O3 2FeO 1/2 O Fe 3.5 Cooling Zone At 1400ºC to 1250ºC,

• Theα1 formC₂S crystallizes to the more hydrolizable βC₂S form. • TheC₃Aand C₄AF crystallize and finally the molten sulfates crystallize.

4. Cyclone

4.1 Pressure Drop

• TheDp through a cyclone for a family of

similar cyclones: 4 2 D Q r cst Dp= ∗ ∗ where:

- Dp is the pressure drop through the cyclone

- r is the fluid density

- Q is the gas flow

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4.2 Thermal Efficiency • go mo go th T T T 1 h ₌ − − where:

- T_go is the temperature of gas at cyclone outlet

- T_go is the temperature of material at cyclone discharge • A normal value for thermal cyclone efficiency is above 95%. This definition is commonly used but the name

"Thermal efficiency" can be considered misleading because the useful heat gained by the material at the cyclone discharge is also related to the cyclone trapping efficiency.

4.3 Trapping Efficiency • i o i t D D D h = − where:

- _{Di is the dust load of gas at cyclone inlet} - _{Do is the dust load of gas at cyclone outlet} • The current value for the trapping efficiency of the top cyclone is around 95%. It was commonly accepted in

the past that the bottom cyclones had a lower efficiency (75-85%) but series of measurements and tower simulation showed a higher efficiency for these cyclones (around 90%).

4.4 Calculation of Material Flow

• With the two following equations expressing the total flow conservation and the tracer flow (i.e. K₂O), the recirculation level can be assessed.

- F_kk +F_KD =F_KL +F_CA

- F_kk∗K_kk +F_KD=F_KL∗K_kk +F_CA∗K_CA

where:

- F_KD: The kiln dust flow (LOI=0) - F_KL: The kiln load flow (LOI=0) - F_kk: The clinker flow (LOI=0) - FCA: The coal ash flow (LOI=0)

- K_kk: Tracer concentration in clinker - K_KD: Tracer concentration in kiln dust - K_KL: Tracer concentration in kiln inlet - K_CA: Tracer concentration in coal ash

(if ash has to be added)

5. Chains

5.1 Guideline

Zone Target (wet) Dry kiln

Free zone length (ratio to kiln diameter) 1.0 to 1.5 1.0 to 1.5

Dust M2/m3 11.0 to 15.0 11.0 to 15.0

Chain length (% of kiln diameter) <75% <75% Plastic zone length (ratio to kiln diameter) 1.0 to 4.0 N/A

M2/m3 5.0 to 8.0 N/A

Chain length (% of kiln diameter) 60% to 70% N/A Preheat lower section zone length (ratio to kiln diameter) 0.5 to 2.5 0.5 to 2.5

M2/m3 7.0 to 10.0 7.0 to 10.0

Chain length (% of kiln diameter) 70% 70% Preheat upper section zone length (ratio to kiln diameter) 0.5 to 2.5 0.5 to 2.5

M2/m3 6.0 to 8.5 6.0 to 8.5

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Zone Target (wet) Dry kiln

Radiation zone length (ratio to kiln diameter) 1 1

M2/m3 8.5 to 11.0 8.5 to 11.0

Chain length (% of kiln diameter) 70% 70%

Global m2/mtpd 2.5-2.8 2.3 – 2.6

Global kg/mtpd 110-130 105-110

Global length Ratio to kiln diameter 6-10 5 – 8

Global length % kiln length 18-25% 17 – 22%

(sources: Marc Brunelle)

• Chain surface: 19m2/t for oval chains vs. 22-25 m2/t for round chains. • For small kilns, ratios are always lower than for larger kilns.

• Ratios are higher for dry kiln compared to wet kiln. • Chainless sections are applied along chain zone aiming to:

- equalize gas temperatures

- serve as a buffer area to equalize varying rates of material transportation - precipitate kiln dust

- allow for installation of thermocouples

Other Rules of Thumb

• 1500 m of installed chains reduces the exit chain gas temperature by 100oC. • A properly designed chain system can lower the SHC by 300 kcal/kg ck. • heat exchange rate: 8.75 kcal/h/m2/C.

• pressure per one meter of chain: 1-2 mm H2O for curtain chain and 2-3 for Gartand chain (note: Garland

chains are abandoned due to practical considerations in maintaining hanging pattern). • For Gartand chain, the thermal effect is 1.5 time higher than curtain chain.

• Wear rate: 80-120 g/t ck for wet kiln and 100-150 for dry kiln. 5.2 Lafarge Corp Data

Kiln Type Impact Chain densities

updated Feb 99 plates Specific Area Gross Area Area Ratio Specific Weight Gross Weight Weight Ratio

M.Brunelle (CTS) m2/m3 m2/m3 m2/mtpd kg/m3 kg/m3 kg/mtpd

C1-C2 C2 C1-C2 C2

(less FE void) (plus all voids) Nominal Prod. (less FE void) (pluss all voids) (Nominal Prod.)

BTH K1(1999) 1SPH 6.46 4.39 1.36 260.12 176.77 54.79 BTH K1(1998) 1SPH 6.44 4.38 1.17 260.26 176.77 47.14 JPA K2 (1998) 1SPH 6.33 4.93 2.57 242.82 189.32 98.46 Averages 6.39 4.65 1.87 251.54 183.05 72.80 STC K1 Dry (cros) 4.90 4.18 1.76 303.00 258.57 109.18 BFD K2 (1998) Dry 5.70 4.70 1.50 269.30 221.90 71.00 ESW K4 (1999) Dry 7.46 5.44 2.96 303.21 220.92 120.37 ESW K4 (1998) Dry 7.42 5.36 3.08 301.27 217.89 125.02 STC K2 (1998) Dry 6.96 6.48 2.44 317.93 296.23 111.57 SCK K1(1998) Dry 8.21 6.34 2.10 309.56 238.92 79.14 SCK K2 (1998) Dry yes X1 7.79 6.16 2.21 274.44 216.96 77.90 Averages 7.26 5.75 2.38 295.95 235.47 97.50

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Kiln Type Impact Chain densities

updated Feb 99 plates Specific Area Gross Area Area Ratio Specific Weight Gross Weight Weight Ratio

M.Brunelle (CTS) m2/m3 m2/m3 m2/mtpd kg/m3 kg/m3 kg/mtpd

C1-C2 C2 C1-C2 C2

(less FE void) (plus all voids) Nominal Prod. (less FE void) (pluss all voids) (Nominal Prod.)

FDA K1(1998) Wet yes X2 4.95 4.36 2.72 280.57 246.86 154.36

FDA K2 (1998) Wet yes X1 5.90 5.13 3.00 333.31 289.84 169.66

RMD K1(1998) Wet 7.16 6.23 2.68 283.75 247.01 106.16

RMD K2 (1998) Wet yes X1 6.54 5.28 2.62 291.05 234.90 116.66

SEA (1998) Wet 4.82 4.07 2.72 189.23 159.84 106.76

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6. Cooler

6.1 Compartments Compartments number <800 tpd: 4 compartments 800-1200 tpd: 5 compartments 1200-2000 tpd: 6 compartments 2000-3000 tpd: 7 compartments 3000-4000 tpd: 8 compartments >4000 tpd: 9 compartments • To the middle of the cooling zone, the ratio between compartment area will be 1.4 (except for the #2).

Recuperation zone • C N k H 1440 Q I ∗ ∗ ∗ ∗ ∗ = ρ . where: - l: cooler width - Q: clinker flow (t/day)

-

ρ

: Clinker apparent density (t/m3) generally 1.25 - H: bed depth (m)

- k: grate efficiency (0.70 for flat grates)

- N: number of stroke per minute (usually 10 to 14spm) - c: the grate course (m)

• N has to be chosen to allow 1.6 * N in case of push.

• The length of the recuperation zone will be set with an air density between 1.45 Nm3/m2*s (Fuller) and 1.55 (IKN) and a heat consumption 800 kcal/kg and 0.85 Nm3/kgkk for the combustion air.

Cooling zone

• The cooler loading will be the factor determining the cooling zone length: - 40 t/m2/day dry process (high pressure fans thick bed depth (60 cm)) - 35t/m2/day wet process (high pressure fans)

- 28 t/m2/day all processes (low pressure fans, thin bed depth (30 cm))

Rules of thumb

• Air velocity above clinker bed: 5 to 7m/s.

• 6 to 10 strokes per minute, cooler stroke length around 5”, clinker speed around 1 to 1.2 m/min. • Clinker granulometry: passing 0.5mm:<15% , remaining at 25mm<10%.

• Void volume: about 0.4 to 0.5. • Clinker bulk density: 89 to 120 lb/ft3.

• Grate cooler: 5-10 kWh/ t, target should be below 5 kWh/t w/o vent air fan. 6.2 Fans

Recuperation zone

• Maintain the flow during a kiln push: the fan maximum pressure has to be 30% higher than the nominal. At constant flow, 15% of security to absorb the pressure variation. It is also a good security to keep 30% of flow reserve between the peak of the curve and the nominal.

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Cooling zone

• They should be able to go from 2.5 to 3 Nm3/kg during a push. Their curve should be flatter and their maximum pressure 30% above the functioning point. 20% increase in flow has to keep 15% safety margin on pressure. Minimum is 30 mbar for single-stage cooler.

Rules of thumb

• Grate plate resistance is directly related to the air flow and represents about 15% of total air resistance. • Basic operating principles:

- Maintain a constant air to clinker ratio - Maintain a constant bed depth

- Remove all excess cooling (vent) air

• The longer the air/clinker contact time, the cooler the clinker.

• The higher the velocity air, the colder the clinker surface, the higher the heat transfer rate from center to edge of the clinker but the lower the between air and clinker edge.

• Average cooling air flow (Lafarge Corp): 3.7 kg/kg kk, 2.9Nm3/kg kk. • Average grate loading: 30 mt/m2/d (the older the lower usually). • Secondary air temperature:

n . SHC ) K 347 .( 3250 T = − .

where:K: heat loss of the cooler in kcal/kgck, SHC in kcal/kgck, n: excess air (ex:1.1) • Airflow:

Chamber # 1 2 3 >=4

Nm3/(m2.s) 2.0-3.5 1.2-1.8 1 <1

6.3 Cooler Efficiency Coefficients a. Recovery Efficiency (ρ): • ca ta sa ca in , ck ta sa m m m h h h h input heat usable total gases recovered by gained heat + + + = = ρ where :

- msa=mass of secundary air in kg/h andhsais the enthalpy of secondary air in kcal/h

- mta=mass of tertiary air in kg/h andhtais the enthalpy of tertiary air in kcal/h

- mca=mass of cooling air in kg/h andhcais the enthalpy of cooling air in kcal/h

• This efficiency depends highly on the quantity of air recovered by combustion. It is higher for wet kilns (∼90%) than for dry kilns (∼70%).

b. Cooling Efficiency • in ck, out ck, in ck, h h -h clinker in input heat clinker by lost heat = = η c. Recovery Factor (k) • ( mta) ta sa

m

k

=

+

−

=

ln

(

1 ρ

)

_or

ρ

₁

_-

_e

-kmsa - k = 0.9 ⇒ bad cooler - k = 1.1 ⇒ poor cooler - k = 1.3 ⇒ good cooler - k = 1.6 ⇒ excellent cooler

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d. Cooler Loss

• Cooler loss = all heat not recovered by combustion air.

• Cooler loss = heat content of clinker leaving cooler (h_ck_,_out ): + heat content of vent air + heat content of coal mill air + heat content of raw mill air + wall heat losses e. Typical Values

(Lafarge Corp data) min max Av. min max Av.

k 0.83 1.67 1.25 η 92% 97.2% 95%

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6.4 Typical Heat Balance Davenport Cooler

Cooler heat & mass balance Davenport cooler Final balance Date:Sept 16 to 18, 97 Clinker (T/d): 2537

Clinker (kg/h): 105725 Ref. temperature: 0°C IN volume volume mass mass Temp. Heat Heat

Nm³/h Nm³/kg ck kg/kg ck kg/h ºC kcal/h kcal/kg ck Cooling air 225671 2.13 2.76 291643 37 2613673 24.7 Hot clinker 1.00 105725 1350 36638913 346.5 Total 225671 2.13 3.76 397368 39252586 371.3 OUT Secondary air 23016 0.22 0.28 29745 974 7540626 71.3 Tertiary air 71770 0.68 0.88 92751 874 20901034 197.7 Raw mill take-off

Coal mill take-off 16232 0.15 0.20 20978 317 1623430 15.4 Vent air 114652 1.08 1.40 148170 167 5976961 56.5 Cold clinker 1.00 105725 143 2916855 27.6 Wall loss 293680 2.8 Total 225671 2.13 3.76 397368 39252586 371.3 Difference: 0 0.00 0.00 0 0 0.0 0.00% 0.00% 0.00% 0.00% 0.00% 0.00% ρ: 75.37%(recovery ratio) k: 1.56 η: 92.04%(cooling efficiency) Cooler loss: 102.26kcal/kgck

Tertiary air Vent

0.68 Nm³/kg ck 1.08 Nm³/kg ck 0.22 Nm³/kg ck 874°C Coal mill 167°C 974°C 0.15 Nm³/kg ck Secondary air 317°C Clinker 105725 kg/h 1350°C

Cooling air Clinker 2.13 Nm³/kg ck 105725 kg/h

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7. Kiln Heat Balance

7.1 Theoretical Heat for Clinker Formation

Perray

• From clinker analysis: Q

(

kcal/kgck

)

=4.11Al₂O₃+6.47MgO+7.64CaO−5.11SiO₂−0.60Fe₂O₃ Lafarge Model • Exothermic reaction 100 160 228 172 S C S C QE ₂ ₃ ∗      ₊ = • _{Decarbonization} _QD₌₄₃₇_.₅₊₀_.₆₆ ₁₀−2 _∗_T₋₀_.₂₂ ₁₀−4 _∗_T2 where: - QE in kcal/kgkk - QD in kcal/kgCaCO3

- _{T is the decarbonatation temp (ºK)} • _{Qtheo = QD - QE}

7.2 Wall Losses a. General Formula • WL=αS(T2−T1)

where:

- WL is the losses in kcal/h - S is the area in m2

- T2 is the wall temperature (ºC) - T1 is the ambient temperature (ºC) - αis defined in the following graph

0 5 10 15 20 25 30 35 40 45 50 55 60 65 100 200 300 400 500 600 T - T° (C) W/M2C v = 14 m/s wind 13 12 11 10 9 8 7 6 5 4 3 2 1 v = 0 m/s (free convection) S S = 0.9 Ambient T° - 20°C Wind:0m/s α

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b. Radiation • kcal/m h 100 273 te 100 273 tp * 96 . 4 * Loss 2 4 4               + −       +

=∈ with: tp: wall temperature, te: external temp. (in C)

Emissivity:∈

material ∈

bricks 0.8

steel 0.95

For oxidized steel ∈=0.996-2.88*10-4.(tp-100) For dusty kiln shell ∈=0.96-5.2*10-4.(tp-100) For silica bricks ∈=0.81-6.08*10-4.(tp-200)

Other data tp ∈ tp ∈

Iron oxide 500C 0.78 Steel oxide 40C 0.94

Zinc galvanized sheet bright 28C 0.23 Steel oxide 370C 0.97

Iron polished 425C 0.144 Steel polished 770C 0.52

Steel dense shinny oxide layer 25C 0.82 Steel pipe 200 0.8

Emissivity Error measurement: Example

Read temperature=65C, emissivity choosen: 1 instead of actual: 0.4 True temperature=t=(273+65).41/0.4 =425K =152C

Loss calculated with read temperature=290kcal/h/m2, Loss with true temperature=510 kcal/h/m2

c. Convection

• Loss=α*(tp−te)1.25kcal/m2h

α: coef exchange 2.6 for vaults 2.2 vertical surfaces 7.3 Kiln Residence Time

Rules of thumb:

• Long kiln: 2-4 hours (Lafarge Corp. average: 155 min), short kiln:40 to 60 minutes. • RPM from 1.5 to 2.5 (short kiln), Long Kiln: 1.2 to 1.8, Lafarge Corp. average: 1.34.

• Le Teil (1998): 1.5 to 2.3RPM improved clinker granulometry: Retained at 20mm: 7.2 to 13.5%, R10mm: 25to 37% Perray • S d N L 19 . 0 T ∗ ∗ ∗ = with: - L Kiln length (m) - N Kiln speed (rpm) - d kiln diameter (m) - S Kiln slope (m/m) Material speed

• Lafarge model in calcination zone:

Ts Tf Tf Ts Tm S d N Vm − + − ∗ ∗ ∗ = 2 19 . 0 with: - Vm: the speed at m - Tm: mat temp at m

- Ts: temp where calcination begins

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7.4 Water Spray • Flow needed = f t T T s w h kg . 9 . 538 ) 100 ( ) .( . / 2 2 1 + − −

= where: T1andT2: uncooled and cooled temp (C) of the gas,w:

gas rate (kg/h),s: specific heat of gas (kcal/kg), t2:water temp. (in C), f :% water evaporated (decimal). • Lafarge corp : from 0 to 0.26kg water/kg clinker, average: 0.14.

7.5 Heat Balance Example a. Davenport 1997 Flow Sheet

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b. Precalciner Heat Balance

plant Davenport kiln Kiln 1 date 13/11/97

Precalciner specific heat consumption 584 kcal/kg ck

heat in %mass kg/hr Temp

(°C) kcal/kg kcal/hr kcal/kg ck heat out %mass kg/hr Temp

(°C) kcal/kg kcal/hr kcal/kg ck Air 99617 712 181.98 18127832 172.52 Tower Exit Gas 188391 358 100.84 18997182 180.80

Primary air 1 2.00% 1992 10 2.40 4788 0.05 O2 2.13% 4013 81.97 328920 3.13

Primary air 2 2.00% 1992 10 2.40 4788 0.05 CO2 45.82% 86313 83.08 7170647 68.24

Inleakage 1 10.00% 9962 10 2.40 23938 0.23 H2O 2.18% 4103 759.59 3116709 29.66

Inleakage 2 0.00% 0 10 2.40 0 0.00 SO2 0.18% 338 59.90 20229 0.19

Tertiary air 86.00% 85670 823 211.21 18094318 172.20 N2 48.87% 92067 90.06 8291338 78.91

Preheater feed 190500 61 11.84 2256252 21.47 Ar 0.83% 1558 44.51 69337 0.66

H2O 0.00% 0 61.04 0 0.00 Bypass Gas 21000 440 126.82 2663285 25.35

Kiln Dust 0 300 68.65 0 0.00 O2 2.00% 420 102.07 42869 0.41

Return Dust 0 350 81.80 0 0.00 CO2 32.14% 6749 104.95 708259 6.74

Coal/Coke 8334 60 16.57 138056 1.31 H2O 2.84% 596 800.12 476879 4.54

Combustion 7361.60 61349445 583.86 SO2 3.77% 791 75.39 59662 0.57

H2O 1.34% 112 60.04 6705 0.06 N2 58.27% 12237 111.49 1364285 12.98

Natural Gas 0 80 43.21 0 0.00 Ar 0.99% 207 54.74 11332 0.11

Combustion 0 0 0.00 Bypass Dust 3810 400 85.46 325607 3.10

H2O 0.00% 0 80.15 0 0.00 Kiln Feed 112921 850 197.04 22249876 211.75

WDF 0 80 44.98 0.00 0.00 Heat of Formation 412.02 46526066 442.79

Combustion 0.00 0.00 0.00 Tower Exit dust 22000 340 79.13 1740957 16.57

H2O 0.00% 0 80.15 0 0.00 Wall Losses 22.00 2484260 23.64

Kiln Gases 49672 904 258.36 12833217 122.13

total in 348122 94711507 901.37 total out 348122 94987233 904.00

difference 0 275726 2.62

0.00% 0.29% 0.29%

c. Kiln Heat Balance

plant Davenport kiln Kiln 1 Date 13/11/97

kg/hr kg/kg ck

fuel kg/hr Temp (°C) LHV (kcal/kg) Tot. kcal/kg Clinker 105075 1.00

Coke/Coal 3572 60 7362 26354660 Kiln Feed 112921 1.07

Natural Gas 0 15 0 0.00 Return Dust 0 0.00

Waste Derived Fuel 0 0 0 0.00 Waste Dust 0 0.00

total combustion air %vol Nm3/hr %mass kg/hr Temp (°C) neutral combustion air %mass kg/hr

Total Combustion Air 29600 38254 Neutral Combustion Air 35852

O2 23.15% 8300

Primary Air 1 4.78% 1415 4.78% 1828 27 CO2 0.04% 14

Primary Air 2 6.21% 1837 6.21% 2374 25 H2O 0.00% 0

Inleakage 1 10.00% 2960 10.00% 3825 25 SO2 0.00% 0

Inleakage 2 0.00% 0 0.00% 0 25 N2 75.53% 27079

Secondary Air 79.01% 23388 79.01% 30226 1065 Ar 1.28% 459

total kiln gas %vol Nm3/hr %mass kg/hr Temp (°C) neutral combustion gas %mass kg/hr

Total Kiln Gas 34667 49672 904 Neutral Combustion Gas 39195

O2 2.01% 696 2.00% 993 O2 0.00% 0 CO2 23.45% 8130 32.14% 15963 CO2 25.71% 10076 H2O 5.06% 1754 2.84% 1410 H2O 3.60% 1410 SO2 1.89% 655 3.77% 1872 SO2 0.31% 121 N2 66.80% 23158 58.27% 28944 N2 69.22% 27130 Ar 0.79% 275 0.99% 490 Ar 1.17% 459

excess air kg/hr water spray kg/hr Temp (°C)

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d. Kiln Summary

plant Davenport kiln Kiln 1 date 13/11/97

Kiln specific heat consumption 250 kcal/kg ck

heat in %mass kg/hr Temp

(°C) kcal/kg kcal/hr kcal/kg ck heat out %mass kg/hr Temp

(°C) kcal/kg kcal/hr kcal/kg ck

Air 38254 846 221.92 8489285 80.79 Total Gas 49672 904 258.36 12833217 122.13

Primary air 1 4.78% 1828 27 6.50 11884 0.11 O2 2.00% 993 221.81 220355 2.10

Primary air 2 6.21% 2374 25 6.01 14256 0.14 CO2 32.14% 15963 239.69 3826133 36.41

Inleakage 1 10.00% 3825 25 6.01 22974 0.22 H2O 2.84% 1410 1049.74 1479875 14.08

Inleakage 2 0.00% 0 25 6.01 0 0.00 SO2 3.77% 1872 168.70 315788 3.01

Secondary Air 79.01% 30226 1065 279.23 8440171 80.33 N2 58.27% 28944 239.63 6935970 66.01

Kiln Feed 112921 850 609.06 68775942 654.54 Ar 0.99% 490 112.52 55097 0.52

H2O 0.00% 0 0.00 0 0.00 Clinker 105075 1358 349.49 36723000 349.49

H2O Spray 0 10 9.97 0 0.00 Heat of Formation 420.00 44131394 420.00

Return Dust 0 300 68.65 0 0.00 Exit dust 0 400 95.32 0 0.00

Coal/Coke 3572 60 16.57 59167 0.56 Wall Losses 75.00 7880606 75.00

Combustion 7362 26292619 250.23 H2O 1.34% 48 60.04 2873 0.03 Natural Gas 0 15 7.70 0 0.00 Combustion 0 0 0.00 H2O 0.00% 0 14.97 0 0.00 WDF 0 0 0.00 0.00 0.00 Combustion 0 0.00 0.00 H2O 0.00% 0 0.00 0 0.00

total in 154747 103619887 986.15 total out 154747 101568217 966.63

difference 0.00 -2051671 -19.53

0.00% -2.02% -2.02%

8. Volatile

8.1 Properties of Volatile Elements a. Basic Volatile Properties

• The raw mix comes with some minor elements (potassium, sodium, sulphur and chlorides) called volatiles. Element Compound Formula Molecular

Weight Melting Point °C Boiling Point °C Heat of Formation -∆H°f kJ/mol Na Oxide Hydroxide Carbonate Sulfate Chloride Na2O NaOH Na2CO3 Na2SO4 NaCl 62.0 40.0 106.0 142.0 58.4 820 322 851 884 801 d 1390 d — 1465 416 427 1131 1385 411 K Oxide Hydroxide Carbonate Sulfate Chloride K2O KOH K2CO3 K2SO4 KCl 94.2 56.1 138.2 147.3 74.6 887 410 891 1069 776 d 1327 d 1689 1410 362 426 1146 1434 1436 Ca Oxide Hydroxide Carbonate Sulfate Chloride Fluoride CaO Ca (OH)2 CaCO3 CaSO4 CaC12 CaF2 56.1 74.1 100.1 136.1 111.0 78.1 2580 d d d≈ 1280 (1450) 772 1380 2850 — — — 1600 — 636 987 288 1430 795 — d=Decomposes, s=Sublimates

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b. Eutectic

• In a multicomponent-system the melt formation is governed by eutectics. Eutectic is a mixture of two or more substances that have a melting point lower than any of the substances of the mixture.

Eutectic Melting System Concentration (% mole) Melting point (°C) Na₂SO₄— CaSO₄ 52 — 48 900 K₂SO₄— CaSO₄ 58 — 42 867 K₂SO₄— Na₂SO₄ 23 — 77 823 K2CO3— CaCO3 60 — 40 750 K₂CO₃— Na₂CO₃ 42 — 58 710 K₂SO₄— KCl 40 — 60 690 KCl — CaSO₄ 68 — 32 688 KCl — NaCl 50 — 50 640 NaCl — Na₂SO₄ 65 — 35 630 KCl — CaCl2 25 — 75 600 NaCl — CaCl₂ 50 — 50 500 c. Vapor Pressure

Vapor Pressure for Volatile Compounds at Different Temperatures

mm Hg 100 200 300 400 500 600 700 760 700 800 900 1000 1100 1200 1300 1400 1500 °C NaOH KOH KCl NaCl Na CO₂ ₃ K CO₂ ₃ K SO 4 2 Na SO₂ ₄

Caution: This graphic is for trend indication only.

We have no indication of the precision of the curves. Do not use for calculation.

Thus, for instance, K is more volatile than Na.

d. Typical Chemical Reaction

• n

(

4

)

m 2 O2 2 m SO m MeO n SO

Me ↔ + + where: Men can be: Ca, K2,Na2

• The equilibrium constant of that reaction has this formula:

[

] [ ] [ ]

( )

m n m m n SO Me O SO MeO K 4 2 / 2 2 =

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e. Parameters Influencing the Volatilisation Process

Influence of kiln gases on the volatility of the circulating elements Kiln atmosphere vapor pressure Sodium v Potassium v Sulphur v Chloride v CO2 ⇑ ⇓ ⇓ ⇑ H2O ⇑ ⇑ ⇑ ⇑ ⇑ O2 ⇓ ⇑ ⇑⇑ SO2 ⇑ ⇓ Effect of fineness on v at 1300°C K2O v Na2O v SO3 v 1.7% > 200 µm 21.8 % > 90 µm 0.89 0.42 0.63 < 90 µm 0.89 0.46 0.63 < 60 µm 0.93 0.45 0.65 8.2 Volatilization Process

• Volatiles will start to volatilize (evaporate) from the liquid phase as soon as the temperature increases.

• A fraction of those elements (or compounds) will be vaporized in the burning zone and get entrained with the gases toward the back of the kiln. The vapors will cool down together with the gas stream and recondense before leaving the kiln or in the dust collector. The condensation takes place on any cool surface, mostly on the dust carried by the gas.

- F_i : flux of volatile componenti brought by fuel (g/kg ck)

- M_i : flux of volatile componenti brought by raw mix (g/kg ck)

- C_i : flux of volatile componenti going out with the clinker (g/kg ck)

- L_i : flux of volatile componenti lost with gas and dust (g/kg ck) ( loss)

- Ki : flux of volatile componenti in the kiln load (g/kg ck) - G_i : flux of volatile componenti in the gas stream (g/kg ck)

a. Volatile Recirculation Model

Fuel Exit gas

& dust

Clinker Raw mix

Gas & dust

Kiln load Trapping Volatilization • Kiln load: vt 1 M tF K − + = • Clinker:

(

tF M

)

vt 1 v 1 C + − − = • Gas stream: vt 1 F vM G − + = • Losses:

(

vM F

)

vt 1 t 1 L + − − =

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Typical volatilization and trapping coefficients

Type of kiln _SO3 _K2O _Na2O

Cl-v t v t v t v t

Wet kiln without dust wasting 0.59 0.76 0.45 0.81 0.12 - 0.99 -Wet kiln with dust wasting 0.72 0.63 0.53 0.51 0.24 0.68 0.99

-Long dry kiln 0.65 0.87 0.65 0.81 0.21 0.45 0.99

-Preheater kiln 0.80 0.90 0.69 0.96 0.26 0.79 0.99 0.99

Precalciner kiln 0.55 0.96 0.49 0.98 0.55 0.60 0.99 0.99

(Prepared from average volatile balances made within Lafarge) Typical concentration factors of volatiles in the kiln load (kiln load / raw mix ratio)

Na2O and K2O 2 to 10

SO3 4 to 20

Cl- 20 to 100

b. Evolution of Volatiles During Transitions • If M(θ) is a step atθ = 1 then:

(

)( )

/T 1 0 1 K K vt K ) ( K θ = + − θ where:

- K₀ : previous kiln load composition - K₁ : new kiln load composition

- θ : time (to avoid confusion with t, the trapping coefficient)

- T : the time required by a given mass of volatile to complete a cycle - M(θ) : flux of volatile from the raw mix at timeθ

- F(θ) : flux of volatile from the fuel at timeθ - K(θ) : flux of volatile in the kiln load at timeθ

Rules of thumb

• Circulating kiln load : 1.7 to 2.1 kgload/kg clinker.

• Generated dust: Lafarge Corp average for LD kilns:0.6, from 0.2 to 1.34 (BFD). • Generated dust: short kiln: 100 to 150g/kgck, Lepol Grate: 50g/kgck.

c. Volatile Cycle • v 1 t C − =

- t is the time between the trapping and the

burning zone

- v is the volatilization coefficient

- C is the cycling time

Chlorine: v = .99 5-6 days

:

SO₃ v = .6 5-7 hours

8.3 SO₂- SO₃

a. General

• Sulfur is found in:

- Clinker raw material (combined form of sulfur or sulfate). - Combustibles (S in the form of organic components).

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Sulfur Behaviour

Sulfur Input Locations to Precalciner Feed: as SO4, 90-95% capture as FeS2, 35-60% capture Fuel Fuel: as SO4or S, 90-95% capt RM 30-40% capture

Formation in the Burning zone

• The following is the thermodynamic equilibrium of sulfur species in a 10% excess air flue gas. The principal product formed in the burning zone will be SO₂.

400 600 800 1000 1200 1400 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 Temperature (ºK) % o f tot a l s u lphur

H2SO4 SO3 SO2

0 20 40 60 80 100

b. What Affects the SO2 Generation in the Burning Zone?

The composition of the kiln load

• Sulfur is preferably linked with alkalies which have a higher stability and a greater chance of being found as alkali sulfate in the clinker (K₂SO₄,Na₂SO₄) themselves being part of bigger compounds. So if the kiln load composition has a molar excess of K₂O−Na₂O available (not combined with chlorine) vs SO , the₃ SO₂

generated from the load will be lower (sulfur, alkali, molar ratio < 1.2).

The burning zone temperature

• At lower temperature, less CaSO₄or alkali sulfates will decompose to form SO₂ and the SO₃ level in the clinker will be higher.

The O2level 0.0 0.5 1.0 1.5 2.0 2.5 3.0 Oxygen % 0 500 1000 1500 2000 S O2 pp m SO3 0 0.2 0.4 0.6 0.8 1.0 0 1.0 2.5 5.0 %O2 1400°C 1200°C 1000°C v

The residence time in the burning zone

• The longer the time the material stays in the burning zone, the higher the chance for SO₂ to volatilize.

Back-end

• If the raw mix contains sulfur compounds (i.e. FeS₂ = pyrite), the combustion of these compounds generates

2

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c. SO3 Volatilization in Calciner 90 91 92 93 94 95 96 97 98 99 100 0 0 0 0 0 0 0 0 0 0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 0 0 0 0 0 0 0 0 0 0 40 50 60 70 80 90 00000000000000000000000000000000000000000000000000000000000000000000000000000 00000000000000000000000000000000000000000000000000000000000000000000000000000 00000000000000000000000000000000000000000000000000000000000000000000000000000 00000000000000000000000000000000000000000000000000000000000000000000000000000 Combustion efficiency (%) S O 3 v o lat ilizat io n (% ) d. Trapping

• SO2 is stable above 900ºC but starts to be

trapped by CaCO₃ and CaO at lower temperatures. There is a large excess of

3

CaCO in the preheater, which explains a high trapping coefficient (95% "dry" scrubbing).

Lab experience (H. Ritzmann, Neubeckum).

400 500 600 700 800 900 1000 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 0 0 0 0 0 0 0 0 0 0 0 20 40 60 80 00000000000000000000000000000000000000000000000000000000000000000000000 00000000000000000000000000000000000000000000000000000000000000000000000 00000000000000000000000000000000000000000000000000000000000000000000000 Temperature (ºC) S O 2 tra ppe d (% o f tota l) • CaCO3 +SO2 +1/2O2 →CaSO4 +CO2.

• In a precalciner kiln, the decarbonated limestone captures more actively SO , especially with a high level of₂

Oxygen and the following equilibrium is shifted to the left: CaSO₄ ↔CaO+SO₂+1/2O₂.

• For this reason, precalciner kilns are able to absorb rather high concentrations of SO in the gas coming from₂

the kiln.

8.4 Build-up and Rings

• After condensation and before solidification of the volatiles, the dust particles will be sticky and tend to agglomerate on solid objects: kiln walls, chains or lower cyclones of preheater tower.

• The sulphur build-up usually occurs where the temperature is between 800°C and 1100°C: kiln walls and chains for a long kiln, smoke chamber and lower cyclone for a preheater kiln. In those build-ups, the following sulfates are most commonly found: Arcanite (K₂SO₄), Anhydrite (CaSO₄), Glaserite (K₃Na (SO₄)₂),

Ca-Langbeinite(K₂Ca₂(SO₄)₃) and sulfate spurrite (Ca₂(SiO₄)₃CaSO₄).

• In a long kiln, the build-ups are formed below the internal exchanger. This takes place in the kiln load so the build-ups formed this way are naturally destroyed in the majority of the cases. In small diameter kiln, however, a sulfate ring can appear.

• Chlorine will condense in the 600°C to 700°C zones, that is in the chains for a long kiln.

• Operational difficulties when the concentration of circulating elements in the load material exceeds the following levels (on clinker basis):

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8.5 Volatile Balance Example : Davenport 1997

Flow Loss of ign Moisture SO3 K2O Na2O Cl

t/h % * % % % % % Raw mix 168.500 35.410 0.000 0.897 0.500 0.090 0.001 Clinker 105.075 0.000 0.000 0.610 0.710 0.130 0.010 Kiln load - 5.210 0.000 2.450 1.099 0.760 0.101 Recirculated dust 22.000 5.000 0.000 1.440 0.580 0.100 0.001 Injected prod 0.000 0.000 0.000 0.000 0.000 0.000 0.000 Waste dust 3.810 5.200 0.000 11.230 2.073 0.493 0.255

Flow Ash Moisture S K2O (ash) Na2O (ash) Cl

t/h (as rec) % (as rec) % (as rec) % % % (as rec) %

Coal 8.680 10.460 5.570 1.020 2.100 0.290 0.000

Coke 3.720 0.510 4.590 3.040 1.100 2.780 0.000

Flow SO2 Dust (dry) Dust SO3 Dust K2O Dust Na2O Dust Cl Loss of ign

kg/h kg/h % % % % % *

Stack 908.18 0.00 0.00 0.00 0.00 0.00 0.00

Mass Balance

Flow CO2 Flow CO2=0

dry t/h % t/h

Raw mix 168.5 35.4 108.83

Recirculated dust 22.0 5.0 20.90

Coal 8.2 - 1.13 ««| (Coal; Flow CO2=0: Ash + S converted to SO3 + Cl)

Coke 3.55 - 0.30 ««| (LWF; Flow CO2=0: Ash + S converted to SO3 + Cl)

Injected prod 0.00 0.00 0.00

Total inlet - - 131.17

Clinker 105.08 0.00 105.08

Recirculated dust 22.00 5.00 20.90

Waste dust 3.81 5.20 3.61

Stack 1.14 0.00 1.135 (Stack; Flow CO2=0: Dust + SO2 converted to SO3 + Cl)

Total outlet - - 130.72 ¯ Inlet-outlet: 0.44 (st/h LOI=0)

Flow Rate Adjustment

Weighting Flow Flow dry Flow CO2=0 Flow CO2=0 note - data entry

t/h kg/kgkk t/h kg/kg kk • Enter weighting factors

Raw mix 0.50 168.2 1.60 108.61 1.03 in boldface

Recirculated dust 0.00 22.0 0.21 20.90 0.20 • total must equal 1.0

Coal 0.00 8.7 0.08 1.13 0.01 • all positive values 0-1

Coke 0.00 3.7 0.03 0.30 0.00 Injected prod 0.00 .0 0.00 0.00 .000 Total inlet - - 130.94 1.24 Clinker 0.50 105.3 1.00 105.30 1.00 Recirculated dust 0.00 22.0 0.21 20.90 0.20 Waste dust 0.00 3.8 0.04 3.61 0.03 Stack 0.00 1.1 0.01 1.14 0.011 Total outlet 1.0 - - 130.94 1.24

note - data entry on "Ignition loss"

*Ignition loss at: %CO2 °C • Concerns LOI determination; impacts the CO2=0 mass balance

• if %CO2; LOI is only CO2 loss • if 1050; LOI is CO2 & moisture loss

(26)

Kiln Audit November 1997 Volatile Balance kiln load hypothesis = 1.30 kg/kg clinker SO3 Waste Dust = 4.063 17.304 31.362 Combustible = 5.154 Stack = 10.231 Return Dust = Trapping = Volatilization = 3.009 14.058 26.208

Raw Mix = 14.783 17.792 Kiln Load =31.850 Clinker = 5.642

Total Trapping Coefficient = 0.544 Volatile Coefficient = 0.823 K2O Waste Dust = 0.750 1.962 7.202 Combustible = 0.173 Stack = 0.000 Return Dust = Trapping = Volatilization = 1.212 5.240 7.029

Total Trapping Coefficient = 0.896 Volatile Coefficient = 0.492 kiln load hypothesis = 1.30 kg/kg clinker Na2O Waste Dust = 0.178 0.387 8.615 Combustible = 0.028 Stack = 0.000 Return Dust = Trapping = Volatilization = 0.209 8.228 8.586

Total Trapping Coefficient = 0.979 Volatile Coefficient = 0.869 Chlorine Waste Dust = 0.057 0.059 1.275 Combustible = 0.018 Stack = 0.000 Return Dust = Trapping = Volatilization = 0.002 1.216 1.257

Total Trapping Coefficient =

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8.6 Circulation in Preheater (Port-la-Nouvelle) a. Kiln Parameters

- Clinker production: 58.33 tph

- Raw mix: 88.4 tph

- Coal: 8.035 tph

- Heat consumption: 833 kcal/kk - O₂ kiln out: 2.5% - O₂ tower out: 3.5%

- Kiln exit gas: 1.286 Nm3/kk - C1 exit gas: 1.412 Nm3/kk - Tower exit gas: 1.505 Nm3/kk - Dust tower exit: 4.2 tph - Kiln exit temp: 1200 ºC

- C1 exit temp: 835 ºC

• The dust from ESP and conditioning tower are mixed after the raw mix feeder.

• In the following diagrams, the ESP dust + conditioning tower dust are called E-P dust. b. Kiln Volatile Balance

SO₃ K₂O Na₂O Cl

Volatilization (%) 68.5 77.5 18.4 99.0

Trapping (%) 100 100 100 100

c. Flow Calculation in Exchanger

• Equation 1: @LOI=0 Mat C2 + Kiln dust = Mat C1 + C1 dust

• Equation 2:

[

K₂O

]

_C₂ +

[

K₂O

]

_Kdust =

[

K₂O

] [

_C₁ + K₂O

]

_dustC₁

Cyclone Efficiency C4 C3 C2 C1 95% 94% 94% 89%

d. Flux per Cyclone

Cl SO3 Na2O C1 Inlets Outlets ∂rel 24.15 25.61 -6% 22.2 21.5 +3% 2.78 2.84 -2% C2 Inlets Outlets ∂rel 11.92 11.4 +4.4% 8.02 16.97 -112% 2.27 2.58 -14% C3 + C4 Inlets Outlets ∂rel 3.32 2.45 +23% 4.59 5.54 -21% 1.51 1.74 -15% • The relative difference inlet/outlet is higher for the top stage:

- only 1 measurement - smaller volatile content

• The SO₃ balance for stage 2 is explained by the SO trapping in material (lower in C1)₂ SO₂ is stable above 700º. The volatile elements are trapped principally in the 2 bottom stages (75%).

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9. Lafarge Corp Typical Ratios

1998 data

Kiln by plant Rated Capacity Thermal load Specific loading Cooler loading

Process Metric tonnes Gcal/hm2 MTPD/M3 MTPD/m2

Long wet Richmond 1 830 5.7 0.6

-Richmond 2 823 6.0 0.6 -Woodstock 1 794 4.1 0.6 -Woodstock 2 839 4.4 0.6 -Fredonia 1 446 3.4 0.5 22.3 Fredonia 2 650 5.7 0.5 31.7 Paulding 1 687 6.1 0.6 22.8 Paulding 2 687 6.1 0.6 22.8

Long dry Brookfield 1 650 4.1 0.5 25.1

Brookfield 2 855 4.4 0.8 35.8 Exshaw 4 1272 3.5 0.5 34.6 Kamloops 617 4.0 0.6 23.8 St-Constant 1 1510 3.9 0.6 33.8 St-Constant 2 1540 4.0 0.6 37.5 Alpena 19 1119 6.2 0.7 47.1 Alpena 20 1105 6.1 0.6 32.2 Alpena 21 1102 5.8 0.6 32.1 Alpena 22 1649 5.1 0.5 34.0 Alpena 23 1657 5.6 0.5 34.2 Joppa 1 1574 6.2 0.6 28.9 Sugar Creek 1 705 4.6 0.7 23.4 Sugar Creek 2 804 4.7 0.7 22.3

Single stage Bath 3267 4.6 0.6 41.1

Preheater Joppa 2 1845 5.4 0.6 29.4 S Preheater Whitehall 1 1344 4.3 1.7 57.7 Whitehall 2 947 3.7 1.8 52.4 AS Preca Exshaw 5 2459 5.3 4.1 57.0 Davenport 2751 2.7 3.4 40.0 Richmond 3 3000 3.1 4.7 38.9

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10. 57 Clinker Reactivity Study (P. Barriac)

Ranges studied: R. quartz on

63µ: 0.5% to

5.3%

Sol. Na2O eq.:

0.1% to 0.9%

Ex. SO3/tot. alk.:

-0.6% to +1.7% C3A perc.: 0% to 12.6% C3S perc.: 43% to 76% C2S perc.: 2% to 31.5% Free CaO perc.: 0.05% to 2.2% Underburning to overburning If we want: ⇓ Siliceous raw mix reject % of soluble alkalies Excess SO3/tot. alkalies % of C3A % of C3S % of C2S % of free CaO Moderate burning with: R.1 or 2-d (easier combination ⇒: small alite

and belite size)

% alkalies and/or clinker % SO3(to have a molar ratio ≥1)

(with Ex. SO3/total

alk.≤1% to limit alite size) at the expense of %C4AF (strong impact if high % sol. alk.) at the expense of %C2S (and/or with %C4AF and %MgO) in favour of %C3S with lime saturation factor to keep C3S = Ct burning zone length (in particular rate of temperature rise) R.28-d. (easier combination ⇒: small alite

and belite size)

% total alkalies (almost of all alkalies are soluble at 28 d)

(with Ex. SO3/total

alk.≤1% to limit alite size) at the expense of %C4AF with %C4AF and %MgO with %C4AF and %MgO (we can free CaO to %C3S) burning zone length ( rates of temperature rise and cooling) R. 1, 2 and 28-d. (easier combination ⇒: small alite

and belite size)

(with Ex. SO3/total

alk.≤1% to limit alite size) at the expense of %C4AF with %C4AF and %MgO with %C4AF and %MgO burning zone length ( rates of temperature rise and cooling) kWh/t (easier combination ⇒: small alite

and belite size)

(keeping a molar ratio at least equal

to 1) at the expense of %C4AF at the expense of %C2S (and/or with %C4AF and %MgO) in favour of %C3S burning zone length (in particular rate of temperature rise) Note: To establish this table, we have taken all the results of the statistical study into account, plus some other results taken from Influence du Profil

thermique – Comparison de 4 études de laboratoire – P. Barriac, June 6, 1995.

Presentation: italics: explaining comments – normal letters: comments on application (method, limits). Clinker Reactivity – supplement to the 10 Basic Facts.

Pyro Processing

Table of Contents

1. Kiln Typical Values

2. Quick Overview Kiln Exit Gas Calculation

3. Pyroprocessing Reactions by Zone

C

S

2

CaO

+

SiO

→

2

CaO

.

SiO

A

C

C

F

SO

SO

4. Cyclone

5. Chains

6. Cooler

ρ

m

m

k

=

+

−

=

ln

(

1

ρ

)

or

ρ

1

-

e

7. Kiln Heat Balance

(

)

8. Volatile

(

)

[

] [ ] [ ]

( )

(

)

(

)

(

)( )

[

]

[

]

[

] [

]

9. Lafarge Corp Typical Ratios

10. 57 Clinker Reactivity Study (P. Barriac)

_or

₁

_-

_e