EVERY SINGLE EQUATION IN CEMENT INDUSTRY

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EVERY SINGLE EQUATION IN CEMENT INDUSTRY

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P A R T  I

CEMENT CHEMISTRY

 

Chapter 1

QUALITY CONTROL FORMULAS

 

1.01 Ignition Loss

Ignition loss is usually determined by tests in a laboratory furnace. It can also be
calculated from the chemical analysis of the kiln feed by the following formula:

1.02 Silica Ratio

 

Large variations of the silica ratio in the clinker can be an indication of poor
uniformity in the kiln feed or the fired coal. Changes in coating formation in the burning zone,
burnability of the clinker, and ring formations within the kiln can often be traced to changes
of the silica ratio in the clinker. As a rule, clinker with a high silica ratio is more difficult to
burn and exhibits poor coating properties. Low silica ratios often lead to ring formations and
low early strength (3 – 7 days) in the cement.

1.03 Alumina – Iron Ratio

Clinker with a high alumina – iron ratio, as a rule, produce cement with high early
strength (1 to 3 days) but makes the reaction between the silica and calcium oxide in the
burning zone more difficult.

1.04 Lime Saturation Factor

This factor has been used for kiln feed control for many years in Europe and only
recently has also found acceptance by American cement manufactures. When the lime
saturation factor approaches unity, the clinker is difficult to burn and often shows excessive
high free lime contents. A clinker, showing a lime saturation factor of 0,97 or higher
approaches the threshold of being “overlimed” wherein the free lime content could remain at
high levels regardless of how much more fuel the kiln operator is feeding to the kiln.

 

 

1.05 Hydraulic Ratio

This index is very seldom used any more in modern cement technology for kiln feed
control.

 

 

1.06 Percent Liquid

Clinker, when burned at a temperature of 1450ºC, Has the following liquid content:

 

 

1.07 Burn ability Index

This is an indicator of the ease of burning for a given clinker. The higher the index
number, the harder the clinker is to burn.

BF = LSF +10SR – 3(MgO + Alkalis)

(find LSF in 1.04 and SR in 1.02)

 

1.09 Bogue’s Formulas for Clinker and Cement Constituents

For a cement chemist, these formulas are the most important and frequently used
indicators of the chemical properties of a cement or clinker. The constituents calculated by
these formulas, however, are only the potential compositions when the clinker has been
burned and cooled at given conditions. Changes in cooling rate or burning temperature can
modify the true constituent composition to a considerable extent.

a) Bogue’s Formulas for Cement Constituents

 

 

b) Bogue Formulas for Clinker Constituents

When appreciable amounts of SO3 and Mn2O3 are present in the clinker, the values of
the chemical analysis have to be recalculated to take into account the amount of CaO that has
been combined with SO3, the amount of free lime present and the Mn2O3.
The values to be used in the Bogue formulas are:

 

To find the amount of CaO that is combined with SO3 as CaSO4 proceed as follows:

 

 

Having determined the appropriate values for the CaO and Fe2O3, one can then
proceed to calculating the potential clinker constituents by using the previously given Bogue
formulas. When the Bogue formulas are used for feed compositions, keep in mind that the
coal ash addition, dust losses, and alkali cycles can alter the final composition of the clinker.
Also use the analysis on a “loss free” basis in the calculations of the constituents.

1.10 Total Carbonates

Total carbonates are usually determined analytically by the acid-alkali titration
method. They can also be calculated from the raw (unignited) analysis as follows:

 

1.11 Total Alkalis as Na2O

The total alkali content in terms of sodium oxide is calculated from the loss free
analysis:

 

1.12 Conversion of Raw Analysis to Loss Free Basis

 

where

Or = percent of oxide (by weight) on a raw basis
Of = percent of oxide (by weight) on loss free basis
L = percent loss on ignition (by weight)
1.13 Conversion of Kiln Dust Weight to Kiln Feed Weight

Dust collected in a precipitator or bag house of a kiln shows a different loss on ignition
than the kiln feed because it has been partially calcined. For inventory control purpose and in
some kiln operating studies it is often necessary to express the weight of dust in terms of
equivalent feed weight.

 

1.14 Calculation of Total Carbonates from Acid-Alkali Titration

This method is only applicable when the MgO content of the sample is known. Values
from the raw (unignited) basis are used for the calculation.

 

1.15 Percent Calcination

Kiln feed or dust samples taken at any location of the kiln are often investigated for
the apparent degree of calcination the sample has undergone.

 

PROBLEMS AND SOLUTIONS

Problems and examples shown in this chapter are all subsequent chapters are arranged
in the same sequence as the formulas are presented in the chapter.

 

Chapter 2
KILN FEED MIX CALCULATIONS

 

2.01 CaCO3 Required to Obtain a Given C3S in the Clinker

This formula should only be used as a quick reference in times when no other
analytical methods, other than the titration method, is available.

where
A = desired C3S in clinker
a = existing C3S in clinker

2.02 Two-Component Mix Calculations

a) To obtain a constant total carbonate content
This method can only be used when the MgCO3 content in the two components is
constant.

 

 

where
x = material A needed (percent by weight)
100 – x = material B needed (percent by weight)
C1 = TC in material A (percent by weight)
C2 = TC in material B (percent by weight)
TC = desired total carbonates

b) Percent of each component needed for a desired CaCO3
Use this formula only when the MgCO3 content in the two components is constant.

 

where
w = weight of material A needed for each 100 unit weights of material B
Cf = CaCO3 desired in mix
C1 = CaCO3 in material A
C2 = CaCO3 in material B

c) To obtain a constant C3S/C2S ratio
Insert the values found from the raw material analysis (on the raw basis)

d) Formulas for mix corrections
Limestone added to a cement rock to correct mix.

where
M = percent CaCO3 desired in mix
F = percent CaCO3 found in mix (before correction)
A = percent limestone already added
L = percent CaCO3 in limestone
X = corrected percent limestone needed to obtain M.

Clay added to a limestone to correct mix.

where
M = percent CaO or CaCO3 desired in mix
F = percent CaO or CaCO3 found in mix
B = percent clay already added
C = percent CaO or CaCO3 in clay
X = percent clay needed to obtain M

 

2.03 Three Component Mix Calculation

a) To obtain a desired LSF and SR

2) Desired compound composition

Whatever targets are set, make sure to make:

 

3) Theoretical compound composition for each component

 

To be calculated from the raw analysis data. Also make sure to use the proper sigh (+
or -).

 

Note: Proceed with the calculations only when the sum total of the compounds
corresponds to the total of the oxides, i.e, for L: total oxides = x1 + y1 + z1 , etc.

4) Calculations, auxiliary matrix

5) Weight of each component needed per unit weight of clinker

All weights units can be used, i.e., the results can be expressed in ton/ton, or kg/kg of
clinker. Results obtained must all be positive numbers. If any of the results are negative, the
desired mix cannot be obtained with the given raw materials. Fighter the targets have to be
changed or other suitable raw materials must be selected.

2.04 Four – Component Mix Calculation

a) Analysis of components (raw basis)

 

 

b) Desired clinker composition

 

c) Theoretical compound composition for each component
(to be calculated from raw analysis data, make sure to use the proper sign)

 

d) Raw material costs

(insert here the total costs per ton, for each raw material. These costs will
later be used to determinate the cost of the calculated mix)

 

Note: The sum total of the oxides of each raw material must equal the
sum total of the compounds of that material.

e) Calculation, auxiliary matrix

note: Make sure to indicate the proper sign in the results.

f) Weight of each component required per unit weight of clinker.
The result can be expressed in terms of kg/kg clinker. Results obtained must all be
positive numbers.

g) Final mix proportions

Note: All results are expressed in terms of a decimal.
h) Cost of the mix
The cost of the mix per unit weight of clinker can be calculated as follows:

 

 

 

2.05 Determination of Chemical Composition

When certain properties are required in a mix, a preliminary investigation of the
needed chemical composition can be made by the following trial and error method. This
method is only applicable when Al2O3/Fe2O3 is higher than 0,64.
Desired:

PROBLEMS AND SOLUTIONS

 

 

The sum total of the primary oxides is 97,91 and x1 has been found earlier to be 98,0.
Therefore, this composition is acceptable since the two agree closely with each other.

 

Chapter 3
KILN FEED SLURRY

 

3.01 Specific Gravity and Pulp Density of Slurries

 

 

3.02 Properties of Water

3.03 Mass of Slurry Required per Mass of Clinker

Metric units can be employed in this formula.

 

3.04 Slurry Feed Rate Required

 

 

3.05 Clinker Production for a Given Slurry Rate

 

C = clinker rate (long tons per hour)
c = clinker rate (short tons per hour)
w1 = mass slurry per mass of clinker
D = pulp density of slurry (kg/m3)
F = mass dry feed per mass of clinker (tons/ton) or (kg/kg)
G = slurry rate (m3/s)
g = slurry rate (gpm)
M = percent moisture

3.06 Clinker Production per Slurry Tank Unit

Note: This formula applies only to the cylindrical portion of the slurry tank.

 

3.07 Specific Gravity of Slurry

 

3.08 Dry Solids per unit Volume of Slurry

CT = tons clinker per meter of slurry tank height
F = mass of dry feed per mass of clinker (kg/kg) or (tons/ton)
R = radius of slurry tank (m)
S = kg solids per m3 of slurry
sgs = specific gravity of dry slurry
sgw = specific gravity of slurry

PROBLEMS AND SOLUTIONS

3.03 A given kiln uses a slurry of 32 percent moisture and the dry solids rate
has bee found to be 1,593 kg/kg clinker. What is the slurry consumption on this
kiln?

 

Chapter 4

CHEMICAL AND PHISICAL PROPERTIES OF
MATERIALS USED IN CEMENT MANUFACTURING

4.02 Bulk Densities of Common Materials

kg/m3
Aluminum                                               2595
Asbestos                                                 3045
Brick (basic)                                         2400-2965
(alu.)                                                    1520-1760
(firecly)                                                1360-1520
Cement (packed)                                     1506
(loose)                                                 1200-1440
Clay (loose)                                          960-1200
Clinker                                                1440-1700
Coal (loose)                                           800-865
Coke                                                      480-640
Concrete (reinforced)                              2325
Gravel (loose)                                          1760
Ice                                                             919
Iron (Cast)                                                7210
Iron Ore                                                   2805
Kiln Feed (dry)                                         1360
Kiln Dust (loose)                                      1040
Limestone                                                1520
Mortar                                                      1665
Fuel Oil                                                      895
Sand                                                         1520
Shale                                                        2480
Slurry (@35 percent H2O)                       1682
Steel                                                         7850
Water                                                      1000

4.03 Typical Coal Analysis

4.04 Typical Fuel Oil Properties

 

4.04 Typical Gaseous Fuel Properties

 

 

4.05 Barometric Pressure at Different Altitudes

 

4.06 Sieve Sizes

 

4.07 Coefficients of Linear Expansion

 

4.09 Properties of Air

 

4.10 Particulate Concentration in Gases

For gases:
1mg/liter = 24,04 m ppm
1mg/m3 = 0,02404 m ppm
where
m = molecular weight of gas

 

 

4.11 Selected International Weights

 

4.12 Selected Minerals and Ores

 

4.13 Classification of Minerals

a) Ingeous rock
These are formed by the intrusion or extrusion of magma or by volcanic activity. The
following minerals belong to this group:
Granite : Crystalline quartz and orthoclase
Orthoclase : Feldspar containing potassium
Plagioclase : Feldspar containing calcium and sodium
Quartz : Silicon dioxide
Biolite : A dark green form of mica consisting of silicate of Fe, Mg, K, or Al
Pyroxene : Silicate minerals containing calcium, sodium, magnesium, iron, or
aluminum
Olivine : Silicate of magnesium and iron
Magnetite : Oxide of iron

b) Sedimentary rock

These are formed by deposits of sedimentation. They can also consist of fragments
of rock deposited in water or by precipitation from solutions and organisms. The following
rocks belong to this group:

Gravel                    Shale             Chalk
Sandstone           Limestone       Marl
Siltstone              Gypsum          Coral

c) Metamorphic rock

These are minerals that have been changed by the action of heat, pressure, and water.
The following minerals belong to this group:

Gneiss :        Laminated or foliated metamorphic rock
Schist :          Crystalline metamorphic rock with foliated structure along
parallel planes
Marble :        Metamorphic crystallized limestone
Quartzite :      Metamorphic sandstone

 

 

4.14 Chemical Formula and Molecular Weight of Common Minerals

 

 

Chapter 5
FORMULAS AND DATA USED IN COMBUSTION
CALCULATIONS

5.01 Termochemical Reactions

5.02 Combustion Constants

Note: Volumes at 16oC and 760 mm Hg.

5.03 Heat Value of Fuel

The heat value of a fuel is usually determined in a calorimeter. For an approximate
indication, the heat value can also be calculated from the ultimate analysis. Values for C
(carbon), S (sulfur), H (hydrogen), etc., are expressed in terms of percent by weight for coal
and in terms of percent by volume for natural gas.

 

5.04 Conversion from “Gross” to “Net” Heating Value’

The net heating value accounts for the heat losses that are experienced for the
evaporation of the moisture in the fuel as well as the water that is generated by the
combustion of hydrogen. Heating values obtained in the calorimeter are “gross” values and
can be converted to the “net” basis by the following formulas:

In Europe it is the custom to express the heating value or fuel consumption in terms of
the “net” basis whereas in North America the “gross” heating value is generally used.

5.05 Analysis of Coal

a) Ultimate analysis
C + H + N + S + O + Ash = 100 percent (by weight)
where

C = percent carbon, H = percent hydrogen, N = percent nitrogen,
S = percent sulfur, O = percent oxygen.
The percent oxygen (O) is not determined by analytical methods but calculated by
difference to make the sum total equal to 100.

b) Proximate analysis
V + free C + ash + m = 100 percent
where
V = percent volatiles,
free C = percent free carbon,
m = percent moisture

The percent free carbon is calculated by difference to make the sum total equal to 100.

5.06 Methods of Expressing Solid Fuel Analysis

Analysis of solid fuels should be reported with a note containing a remark in respect to
the method in which the analysis is expressed. The following are the methods (basis)
frequently used:

a) “as analyzed”
b) “dry basis”
c) “as received”
d) “combustible basis” (moisture and ash free)
e) “as fired”

For inventory control purposes it is of advantage to express coal tonnage, heating
value and its composition on the “dry basis” to eliminate the fluctuations coal undergoes
when it is stored and exposed to weathering.

5.07 Conversion of Coal Analysis to Different Basis

Let
Y = percent C, S, N, or percent ash
O = percent oxygen
H = percent hydrogen
m = percent moisture
subscript:
a = “as analyzed” basis
d = “dry basis”
r = “as received” basis
f = “as fired” basis
c = “combustible” basis
a) To convert from “as analyzed” to “dry” basis

 

b) To convert from “dry” to “as received” basis

Multiply all components, except hydrogen, by the factor

 

c) To convert from “dry” to “as fired” basis
Multiply all components, except hydrogen, by the factor

Note: in b) and c) above, the percent hydrogen is calculated as follows:

 

d) To convert from „as received” to „dry” basis
Multiply each component, except the hydrogen, by the factor

 

e) To convert from “combustible” to “as fired” basis
Multiply each component, except the hydrogen, by the factor

 

f) To convert from “as received” to “combustible” basis
Multiply each component, except the hydrogen, by the factor

The following table shows clearly how the values of a coal analysis and the heating
value can change when the analysis is expressed in different terms.

5.08 Typical Coal Ash Analysis

For a cement chemist, it is important to know the chemical composition of the coal
ash. The majority of the ash, during the burning of coal, enters the clinker and modifies its
chemical composition. On coal fired kilns, it is not only important to maintain a uniform kiln
feed but also to fire the kiln with a coal of uniform composition. In plants, where coal
originates from several different suppliers, provisions should be made to blend these coals
before they are fired in the kiln. A typical analysis of coal ash is shown in the following:

 

5.09 Fuel Ignition Temperature

The approximate ignition temperature of various fuels are

ºC
Coal                 250
Wood              300
Bunker C oil     200
Diesel fuel       350
Natural gas     550

5.10 Percent Coal Ash Absorbed in Clinker

The percent coal ash contained in the clinker can be calculated from the loss-free
analysis of the ash, raw mix, and clinker as follows:

Analysis

 

5.11 Effect of Coal ash on Clinker Composition

Changes in the composition of the clinker as a result of coal ash addition can be
calculated by the following method:
Analysis (loss-free)

 

5.12 Determination of Theoretical Fuel Consumption

Knowing the properties of the coal, kiln feed, and the exit gas allows an engineer to
calculate the coal consumption by using Dr. Kuhl’s formula:
Data needed:

a = constant, 0,266
b = percent carbon in dry coal
c = percent hydrogen in dry coal
d = percent nitrogen in dry coal
e = percent oxygen in dry coal
f = percent sulfur in dry coal
g = percent ash in dry coal

 

 

What is the coal consumption on this kiln?

 

PROBLEMS AND SOLUTIONS

 

 

What is the net heating value of this coal expressed in terms of kcal/kg?

 

5.10 Given the following analysis on a loss free basis;

 

What percent ash does the clinker contain?

 

 

Chapter 6
pH: HYDROGEN – ION – CONCENTRATIONS

 

6.01 Definition of pH

The pH value of a chemical is indicated by the negative log of the hydrogen-ionconcentration
(hc +).

 

 

6.02 Calculation of pH

 

 

P A R T II
B U R N I NG

Chapter 7
TECHNICAL INVESTIGATION OF
KILN PERFORMANCRE

Introduction

The significant formulas for a study of the kiln performance and efficiency are given.
An engineer should follow the sequence in which the formulas are presented herein as many
calculation require the results obtained from earlier computations.

To simplify the engineers task, all the formulas are presented in the form of work
sheets that can be used to arrange the study in an orderly fashion. At the conclusion,
a summary sheet is also given to compile all the significant results of this study.
Data, formulas, and results are presented in metric system units by using the
appropriate worksheets in this chapter.

These worksheets can also be used to perform studies of parts of the kiln system
(e.g., the cooler operation). The reader should have no difficulties in selecting the appropriate
formulas from the worksheets in these instances.
For a complete study, it is essential that the kiln data be selected during a time when
the kiln operates in a stable and uniform manner.

7.01 Technical Information on kiln Equipment

Plant location:____________________________________ Kiln: _____________________
Kiln
Process: ___________________________________________________________________
Manufactured by: ____________________________________________________________
Year placed in operation: ______________________________________________________
Types of clinker produced: _____________________________________________________
Types of fuel burned: _________________________________________________________
Primary air source: ___________________________________________________________
Feeder type: ________________________________________________________________
Type of dust collector: ________________________________________________________
Dust processing: _____________________________________________________________
Preheater
Type: _____________________________________________________________________
Manufactured by: ___________________________________________________________
Year: _____________________________________________________________________
Cooler
Type: ____________________________________________________________________
Manufactured by: ___________________________________________________________
Year: _____________________________________________________________________

Other kiln equipment
Function     Type        Hp
………..          ……..       ………
………..          ……..       …………
………..           ……..      …………

Date of investigation:_________________________________________________________
Tested by: _________________________________________________________________

Chapter 8& 9
KILN PERFORMANCE AND EFFICIENCY

Data needed
Fuel Analysis (Oil or Coal – as Fired)

AA = Percent ash = ………..
AH = Percent hydrogen = ………..
AC = Percent carbon = ………..
AN = Percent nitrogen = ………..
AO = Percent oxygen = ………..
AS = Percent sulfur = ………..
AM = Percent moisture = ………..
AQ = Heat value (kcal/kg) = ………..
AJ = Heat value (kJ/kg) = ………..

 

CALCULATIONS

9.01 Amount of Feed Required to Produce One Kilogram of Clinker

 

 

9.03 Potential Clinker Compounds and Clinker Factors

 

 

Page 102 and 103 are missed

9.11 Products of Combustion

 

Note: For natural gas firing, use the formula 13.08 in chapter 13.

9.12 Weight of Gases from the Feed

 

 

Note: The assumption is made that wasted dust has been 50% calcined. Find a, b, f in 9.01
and k2 in 9.02.

 

9.13 Total Weight of Kiln Exit Gases

Adding the products in 9.11 and 9.12 gives the total weight of exit gas