Raw Mix Design Software: Calculations & Excel Sheet

The raw mix design software is the calculation engine of the raw material preparation: the tool that determines the proportions of the limestone, the clay, the iron ore and the corrective materials that produce the raw meal with the target chemistry, the raw meal that burns into the clinker with the desired phases, the burnability and the cement properties. The Excel workbook of this article is a full raw mix design tool: the working file with the input sheets of the raw material analyses, the proportioning calculations, the module computations (the lime saturation factor, the silica modulus, the alumina modulus), the Bogue composition of the clinker and the correction iterations that the raw mix engineer uses to design and to adjust the mix of the plant.

This article rebuilds the complete methodology of the raw mix design: the target chemistry of the clinker and the cement, the raw material analysis and its corrections (the loss on ignition, the ash, the moisture), the proportioning calculation with the worked numbers of a complete example, the modules and the Bogue phases, the burnability and the quality checks, and the use of the design software in the daily mix control. The Complete Cement Technical Package (931 files: the handbooks, the courses, the Excel tools and the presentations, $249.99 one-time, instant download through the secure PayPal payment) delivers the raw mix design software together with the complete library of the raw mix and the process calculation tools.

1. The Purpose of the Raw Mix Design

The raw mix is the recipe of the clinker: the ground and homogenized blend of the limestone, the clay, the iron ore and the corrections that enters the preheater, and every property of the final cement (the strength, the setting, the durability, the color) traces back to the chemistry of this blend. The raw mix design is the engineering of the recipe, and the software of the package automates the engineering:

• The target composition: the clinker of the ordinary Portland cement targets the oxide ranges: the CaO 62–67 percent, the SiO2 20–24, the Al2O3 4–7, the Fe2O3 2.5–4.5, the MgO below the 5: the mix design finds the raw material proportions that deliver these targets;
• The modules as the control language: the industry steers the mix with the three modules: the lime saturation factor (LSF 92–98), the silica modulus (SM 2.2–2.6) and the alumina modulus (AM 1.3–1.7): the modules translate the chemistry into the burnability and the quality language of the plant;
• The raw materials: the limestone (the calcium source), the clay or the marl (the silica and the alumina), the iron ore or the laterite (the iron correction), and the sand (the silica correction): the proportions of the four (the three-component or the four-component mixes) define the raw meal;
• The daily control: the raw materials vary with the quarry faces, the seasons and the stockpiles, and the mix proportions are recalculated daily: the software of the package gives the laboratory the fast calculation tool of the daily adjustments;
• The quality targets: the designed mix must deliver the clinker quality: the C3S of the 45–65 percent, the stable free lime, the good grindability and the consistent strength: the modules and the Bogue composition of the design are the proxies of the quality that the plant controls.

The raw mix design software is therefore the quality control instrument of the raw side of the plant: the recipe calculator that the laboratory, the process engineer and the quarry planning share, and the package’s workbook is the working tool of the three.

2. The Raw Material Analyses and the Corrections

The raw mix design starts from the chemical analyses of the raw materials, and the software of the package organizes the input data with the corrections that the industry practice applies:

• The oxide analyses: the percentages of the CaO, the SiO2, the Al2O3, the Fe2O3, the MgO and the LOI of each material: the XRF analyses of the representative samples: the inputs of the proportioning calculation;
• The loss on ignition: the limestone carries the CO2 of the carbonate (the LOI of the 38–43 percent), the clay the combined water (the LOI of the 5–12 percent): the analyses expressed as-received, and the proportioning computed on the ignited or the as-received basis with the corrections: the software carries both bases and the conversion rows;
• The moisture correction: the free moisture of the quarry materials (the limestone at the 1–3 percent, the clay at the 5–20 percent in the wet seasons): the wet basis versus the dry basis of the proportioning: the software’s moisture rows correct the feed proportions to the actual as-mined basis;
• The ash correction: the fuel ash of the kiln enters the clinker (the coal ash at the 10–20 percent of the fuel weight, the 1–2 percent of the clinker): the design includes the ash input with the known fuel rate: the software’s ash rows add the fuel contribution to the clinker chemistry;
• The minor components: the MgO, the alkalis, the sulfates, the chlorides and the phosphates of the materials: the limits of the standards and the process cycles (the alkali and the chloride cycles of the preheater) checked in the design: the software flags the exceedances.

The corrections of the analyses are the accuracy of the design: the raw mix computed on the corrected basis burns the designed clinker, and the mix computed on the raw basis misses the target by the percent of the corrections: the workbook’s correction discipline is the first value of the tool.

3. The Proportioning Calculation: The Method

The proportioning of the raw mix is the solution of the material balance: the proportions of the components are chosen so that the weighted oxide totals of the mix meet the module targets. The classical method of the industry, and the method of the package’s software, proceeds in the steps:

• The formulation: the unknown proportions of the components (x of the limestone, y of the clay, z of the iron ore, per 100 parts of the mix): the oxide balances written for the target oxides: the linear system solved for the proportions;
• The module formulation: the practical method fixes the target modules and solves: the LSF target fixes the ratio of the lime to the silica-alumina-iron: the SM target fixes the silica to the alumina plus the iron: the AM target fixes the alumina to the iron ratio: the three equations in the three unknowns (the four-component mixes add the fourth equation of the SiO2 target);
• The iterative adjustment: the spreadsheet method of the software iterates: the initial proportions entered, the modules computed, the proportions adjusted by the hand or by the solver until the modules converge on the targets: the package’s workbook carries the iteration rows with the computed modules beside the targets;
• The least-squares method: the modern tools solve the over-determined systems by the least squares: the proportions that minimize the squared deviations of all the target oxides: the more robust method for the variable materials: the optional solver row of the workbook;
• The verification: the designed mix’s full oxide composition computed and checked: the sum of the components, the modules within the tolerances (the LSF ±1, the SM ±0.1, the AM ±0.1), the minor components within the limits: the verification block of the software.

The proportioning method of the software turns the recipe problem into the arithmetic of the worksheet: the targets in the yellow cells, the proportions in the computed rows, and the modules and the composition in the verification columns: the design at the glance.

4. The Worked Example: The Design of an Ordinary Mix

Follow the complete worked example of the raw mix design with the realistic raw material analyses of the ordinary limestone-clay-iron mix:

Component	Limestone (%)	Clay (%)	Iron ore (%)
CaO	51.0	2.5	0.5
SiO2	1.8	62.0	8.0
Al2O3	0.6	16.0	4.0
Fe2O3	0.4	6.0	80.0
LOI	42.0	8.0	1.0

The design targets: the LSF of the 94, the SM of the 2.4 and the AM of the 1.5. The proportioning: the mix of the 100 parts with the limestone x, the clay y and the iron z:

• The initial proportions: the classical starting point of the industry: the 78 percent limestone, the 19 percent clay and the 3 percent iron ore: the computed oxides of the mix: the CaO = 0.78 × 51.0 + 0.19 × 2.5 + 0.03 × 0.5 = 39.78 + 0.475 + 0.015 = 40.27 percent as-received: the ignited basis (the mix without the LOI: the ignited content = 100 − (0.78 × 42 + 0.19 × 8 + 0.03 × 1) = 100 − 34.43 = 65.57 percent): the ignited CaO = 40.27 / 0.6557 = 61.4 percent;
• The ignited composition: the SiO2 = (0.78 × 1.8 + 0.19 × 62 + 0.03 × 8) / 0.6557 = (1.404 + 11.78 + 0.24) / 0.6557 = 13.42 / 0.6557 = 20.47 percent; the Al2O3 = (0.78 × 0.6 + 0.19 × 16 + 0.03 × 4) / 0.6557 = (0.468 + 3.04 + 0.12) / 0.6557 = 3.63 / 0.6557 = 5.53 percent; the Fe2O3 = (0.78 × 0.4 + 0.19 × 6 + 0.03 × 80) / 0.6557 = (0.312 + 1.14 + 2.4) / 0.6557 = 3.85 / 0.6557 = 5.87 percent: the ignited composition sums with the minor oxides to the 100 percent;
• The modules of the mix: the LSF = 100 × 61.4 / (2.8 × 20.47 + 1.2 × 5.53 + 0.65 × 5.87) = 6,140 / (57.32 + 6.64 + 3.82) = 6,140 / 67.78 = 90.6; the SM = 20.47 / (5.53 + 5.87) = 20.47 / 11.40 = 1.80; the AM = 5.53 / 5.87 = 0.94: the LSF below the 94 target, the SM far below the 2.4 and the AM below the 1.5: the initial mix is under-limed and short of the silica: the iron ore is too high;
• The corrections: the iron ore reduced (the iron comes from the clay’s own 6 percent), the clay raised for the silica, and the limestone raised for the LSF: the adjusted proportions of the 80 percent limestone, the 17 percent clay and the 3 percent iron: the recomputed ignited composition: the CaO = 62.0, the SiO2 = 21.5, the Al2O3 = 5.2, the Fe2O3 = 3.5: the modules: the LSF = 100 × 62.0 / (2.8 × 21.5 + 1.2 × 5.2 + 0.65 × 3.5) = 6,200 / (60.2 + 6.24 + 2.28) = 6,200 / 68.72 = 90.2, the SM = 21.5 / 8.7 = 2.47, the AM = 5.2 / 3.5 = 1.49: the SM and the AM now in the target bands, the LSF still short of the 94: the silica of the clay binds the lime: the design would need the higher-calcium limestone face or the sand correction;
• The interpretation: the example shows the real dynamics of the design: the LSF, the SM and the AM pull against each other, and the material availabilities of the quarry (the limestone quality, the clay quality) set the achievable design window: the software’s iteration rows show the engineer the convergence of the modules with every adjustment.

The worked example of the article demonstrates the complete arithmetic of the mix design: the ignited-basis conversion, the module computation, the iterations and the interpretation, the method that the package’s software automates in the workbook cells.

5. The Modules and Their Meaning

The three modules of the raw mix are the control language of the industry, and the software of the package computes them continuously:

• The lime saturation factor: LSF = 100 × CaO / (2.8 × SiO2 + 1.2 × Al2O3 + 0.65 × Fe2O3): the ratio of the actual lime to the lime that the silica, the alumina and the iron can fully combine with: the LSF of the 92–98 for the ordinary mixes: the LSF above the 100 cannot burn completely (the free lime remains), and the LSF below the 90 starves the alite and drops the strength: the LSF is the primary burnability and quality control of the kiln;
• The silica modulus: SM = SiO2 / (Al2O3 + Fe2O3): the 2.2–2.6 of the ordinary mixes: the SM measures the ratio of the silicates to the flux: the high SM reduces the liquid phase of the burning zone (the harder burning, the higher the required temperature), and the low SM increases the liquid and the coating (the softer burning but the risk of the balling and the rings): the SM balance of the burnability;
• The alumina modulus: AM = Al2O3 / Fe2O3: the 1.3–1.7 of the ordinary mixes: the AM splits the flux into the aluminate and the ferrite: the high AM raises the C3A of the clinker (the higher early strength and the higher heat of the hydration, the lower sulfate resistance), and the low AM raises the C4AF (the better sulfate resistance, the lower burning temperature): the AM of the white cement and the special cements set the special ranges;
• The combined steering: the three modules together define the burnability window of the kiln: the LSF at the 93–95, the SM at the 2.3–2.5 and the AM at the 1.4–1.6 give the smooth burning with the stable coating: the mix design targets the window of the plant’s kiln and fuel;
• The tolerance band: the daily control holds the modules within the tight tolerances: the LSF ±1.0, the SM ±0.1 and the AM ±0.1: the software’s flag cells color the out-of-band modules red: the daily mix control of the plants works to the flag thresholds.

The modules of the design are the bridge between the chemistry and the process: the same numbers that the laboratory computes are the numbers that the kiln operator watches, and the software of the package keeps the two sides in the one file.

6. The Bogue Composition of the Clinker

The designed raw mix converts into the clinker composition through the Bogue equations, and the software computes the potential phase composition of the clinker from the ignited mix chemistry (adjusted for the fuel ash):

• The Bogue equations: the classical formulas of the cement chemistry: the C3S = 4.07 × CaO − 7.60 × SiO2 − 6.72 × Al2O3 − 1.43 × Fe2O3; the C2S = 2.87 × SiO2 − 0.754 × C3S; the C3A = 2.65 × Al2O3 − 1.69 × Fe2O3; the C4AF = 3.04 × Fe2O3: with the composition of the adjusted example (the CaO 62.0, the SiO2 21.5, the Al2O3 5.2, the Fe2O3 3.5): the C3S = 4.07 × 62.0 − 7.6 × 21.5 − 6.72 × 5.2 − 1.43 × 3.5 = 252.3 − 163.4 − 34.9 − 5.0 = 49.0 percent; the C3A = 2.65 × 5.2 − 1.69 × 3.5 = 13.78 − 5.92 = 7.86 percent; the C4AF = 3.04 × 3.5 = 10.64 percent; the C2S = 2.87 × 21.5 − 0.754 × 49.0 = 61.7 − 36.9 = 24.8 percent: the phase totals of the clinker at the 92–98 percent with the minor components;
• The phase roles: the alite (C3S) drives the early strength and the hydration heat, the belite (C2S) the late strength, the aluminate (C3A) the early reactivity and the setting control, and the ferrite (C4AF) the burning and the sulfate resistance: the phase balance of the design is the quality balance of the cement;
• The design targets: the ordinary Portland clinker targets the C3S of the 45–65 percent, the C3A of the 6–12 and the C4AF of the 8–12: the cement types (the sulfate-resisting, the low-heat, the white) set the modified targets: the software’s Bogue row checks the design against the type requirements;
• The potential composition caveat: the Bogue composition is the potential composition: the actual phases of the clinker depend on the burning, the cooling and the minor elements: the Bogue numbers are the design basis, and the microscope and the XRD verify the actual phases: the software documents the distinction.

The Bogue calculation of the software completes the design: the raw mix proportions lead to the modules, and the modules lead to the phase composition of the clinker: the full chain of the design in the one workbook.

7. The Burnability of the Mix

The designed mix must burn, and the burnability of the raw meal is the practical quality that the software estimates with the modules and the minor components:

• The burnability indices: the laboratory burnability test of the industry: the raw meal pelletized and fired at the 1,400–1,500°C in the laboratory kiln, and the free lime of the fired pellets measured: the free lime below the 1.5–2.0 percent at the 1,450°C indicates the good burnability: the test is the standard quality gate of the raw meal;
• The module-based estimates: the empirical correlations of the burnability from the LSF and the modules: the high LSF (above the 96) and the high SM (above the 2.6) raise the burning temperature and the free lime risk: the low AM (below the 1.2) lowers the liquid phase temperature: the software’s burnability row warns the engineer of the difficult designs;
• The minor element effects: the magnesium, the alkalis, the sulfates, the phosphorus and the fluorides change the burnability: the magnesium and the alkalis lower the liquid formation temperature, the phosphorus retards the alite formation, the fluorides act as the mineralizers: the software’s minor element rows flag the concentrations beyond the limits;
• The fuel and the kiln interaction: the burnability of the mix must match the kiln’s capability: the flame temperature, the residence time and the fuel: the design of the difficult mix (the high LSF with the low-heat fuel) is adjusted to the burning capability of the line: the process engineer of the plant balances the chemistry against the burning;
• The clinker quality checks: the free lime of the produced clinker (the target below the 1.0–1.5 percent), the density, the grindability and the strength: the design’s burnability predictions verified against the production: the continuous loop of the design and the measurement.

The burnability chapter connects the design to the kiln: the raw mix software of the package not only computes the chemistry but also warns of the burnability risks, and the engineer uses the warnings to steer the mix into the burnable window of the line.

8. The Daily Mix Control with the Software

The raw mix design software serves not only the one-time design but also the daily mix control of the plant, and the workbook of the package is built for the routine use:

• The daily adjustments: the quarry faces change the limestone chemistry (the CaO of the face moves with the strata), the seasons change the moisture, and the stockpile segregation changes the feed: the laboratory samples the feed daily, updates the analyses and recomputes the proportions: the software’s fast iteration rows return the adjusted mix in the minutes;
• The XRF integration: the XRF analyzer of the plant delivers the oxide analyses of the raw materials and the raw meal in the minutes: the results entered into the software’s input rows, the modules of the produced meal computed and compared with the targets: the deviation of the produced modules from the design drives the corrections of the day;
• The automatic blending: the modern plants blend the raw materials in the prehomogenization and the dosing with the automatic control: the software’s computed proportions become the set points of the proportioning feeders: the manual design and the automatic control share the numbers;
• The homogenization check: the raw meal silo blending compensates the short-term variations: the standard deviation of the raw meal CaO in the silo (the target below the 0.2–0.3 percent) monitored: the software’s statistics rows (the mean, the standard deviation, the range) report the quality of the homogenization;
• The reporting: the daily mix report of the laboratory: the analyses, the proportions, the modules and the deviations: the report format of the software’s summary sheet, the document that the process manager reads with the kiln report.

The daily control practice is the value of the software: the raw mix design is not the one-time exercise of the laboratory but the daily rhythm of the plant, and the package’s workbook is the standing instrument of the rhythm.

9. The Special Cements and the Alternative Raw Materials

The raw mix design software extends beyond the ordinary limestone-clay mixes to the special cements and the alternative materials, and the workbook of the package carries the flexibility:

• The white cement: the iron oxide content minimized (the Fe2O3 below the 0.4–0.5 percent of the raw mix) with the low-iron limestone, the kaolin and the white sand: the AM of the white mixes pushed to the 8–20: the design of the white cement burns at the higher temperatures with the special fuels: the software’s rows handle the extreme AM ranges;
• The sulfate-resisting cement: the C3A limited to the 3–5 percent: the low-AM mix (the iron ore added to bind the alumina as the ferrite): the design targets the C3A band of the standard: the software’s Bogue row checks the limit;
• The low-heat cement: the C3S reduced for the low hydration heat (the dams and the mass concrete): the LSF and the C3S targets adjusted: the design window of the low-heat clinker;
• The alternative materials: the fly ash, the slag, the shale, the sandstone, the copper slag and the other secondary raw materials: each with its oxide signature: the software’s multi-component rows (up to the six-component mixes) include the alternatives in the proportioning;
• The waste-derived corrections: the alternative fuels contribute the ash and the minerals to the clinker (the tires with the steel, the RDF ash, the sludge): the design accounts the fuel contributions: the software’s ash rows are the standing tool of the alternative fuel plants.

The special cements chapter shows the range of the raw mix design: the same method and the same software serve the ordinary and the special products, and the workbook of the package is the flexible instrument of the whole product range of the plant.

10. The Software in the Plant: The Workflow and the Reports

The raw mix design software of the package fits into the workflow of the plant laboratory and the process control, and the practice of the well-run plants follows the standard cycle:

• The sampling: the raw material samples from the quarry faces, the crusher output and the stockpiles; the raw meal samples from the mill and the silo: the sampling frequency of the day for the raw meal and the week for the quarry faces;
• The analysis: the XRF analyses of the samples, the LOI and the moisture determinations: the analysis results entered into the software’s input sheets: the corrections applied automatically;
• The design: the proportions computed to the targets, the modules and the Bogue checked, the burnability warnings reviewed: the design output of the day: the set points of the feeders;
• The control: the produced raw meal’s modules compared with the targets on the hourly control chart: the deviations corrected by the feeder adjustments: the software’s flag rows and the statistics rows support the control;
• The reporting: the daily, the weekly and the monthly mix reports: the averages, the deviations, the trends: the reports of the software feed the process review meetings and the quality audit files: the documentation of the raw side of the plant.

The workflow chapter shows the software at the center of the raw material quality system: the same workbook carries the analyses, the design, the control and the reporting, and the plant that runs the discipline runs the raw side of the process on the numbers of the file.

11. Frequently Asked Questions

What are the typical raw mix targets of the ordinary Portland cement?

The ordinary mixes target the LSF of the 92–98, the silica modulus of the 2.2–2.6 and the alumina modulus of the 1.3–1.7, corresponding to the clinker with the C3S of the 45–65 percent, the C3A of the 6–12 and the C4AF of the 8–12: the targets adjusted to the plant’s raw materials, the kiln and the fuel.

How is the raw mix proportioning calculated?

The proportioning solves the material balance: the proportions of the limestone, the clay and the corrections chosen so that the ignited-basis oxide composition of the mix meets the module targets. The classical method solves the linear balance equations, and the spreadsheet software iterates: the proportions entered, the modules computed, the proportions adjusted until the targets converge: the package’s workbook automates the iteration.

Why is the loss on ignition corrected in the design?

The LOI of the raw materials (the carbonate CO2 of the limestone at the 38–43 percent, the clay water at the 5–12) means that the as-received oxides are diluted: the 40 percent CaO of the as-received limestone is the 65–70 percent CaO of the ignited material. The design computes the ignited-basis composition (the composition after the LOI burns off) because the clinker chemistry follows the ignited proportions, and the software carries both bases with the conversion rows.

What does the free lime of the clinker tell about the raw mix?

The free lime (the uncombined CaO of the clinker) is the measure of the burnability and the burning: the target below the 1.0–1.5 percent at the stable operation. The high free lime signals the over-limed mix (the high LSF), the under-burning, the coarse raw meal or the cold burning zone, and the process engineer corrects the mix, the fineness or the flame: the free lime is the daily feedback of the raw mix design.

How often is the raw mix design recalculated?

The daily control recalculates the mix with every change of the material quality: the quarry face changes, the stockpile turnovers, the seasonal moisture changes, the fuel changes: in the practice the proportions are re-optimized daily from the XRF results, and the full design review is repeated after the major material changes and the capacity modifications.

Is the raw mix design software included in the package?

Yes: the Complete Cement Technical Package (931 files) includes the original raw mix design software workbook with the input sheets, the proportioning calculations, the module and the Bogue computations and the iteration rows, together with the raw mix training materials, the process handbooks and the complete library of the cement engineer: the purchase below delivers the file and the package.

12. Conclusion

The raw mix design software is the calculation engine of the raw material preparation: the analyses of the limestone, the clay and the corrections converted through the ignited-basis corrections into the proportions of the mix, the modules (the LSF, the SM and the AM) steered to the targets, the Bogue phases of the clinker checked, and the burnability and the daily control carried on the same numbers. The worked example of the article (the 80 percent limestone, the 17 percent clay and the 3 percent iron mix with the modules of the 90.2 LSF, the 2.47 SM and the 1.49 AM) demonstrated the complete arithmetic of the design with the concrete values.

The software, the worked method and the complete library of the raw mix and the process knowledge are part of the Complete Cement Technical Package: the 931 files, the one-time payment of $249.99, the instant download and the lifetime access. The purchase button below delivers the raw mix design software and the whole package of the cement engineer in one download.

This file is part of the Complete Cement Technical Package (931 files) available from cementequipment.org. Respective rights holders; library copy for the licensed single user.