Phlego cement - method for tailored composition design

Abstract

Phlego cement is a recently developed cement composition that avoids the use of carbonate-containing rock in favor of low- or no carbon igneous rock compositions. A presently preferred Phlego raw meal composition range is 40-55% silica, 5-15% CaO and 8-15% total alkalis (Na2O and K2O) with no significant carbon content ( 2% by weight or less). However, it may be the case that no single igneous rock type with a composition in this range is locally available at a production site. This work addresses this possible problem by describing how two or more non-Phlego compositions can be combined to provide a Phlego raw meal composition.

Description

[0001] Phlego Cement - Method for Tailored Composition Design

[0002] FIELD OF THE INVENTION

[0003] This invention relates to making raw meal for Phlego cement .

[0004] BACKGROUND

[0005] In previous work, we have described a new cement composition, referred to as Phlego cement, that avoids the use of carbonate-containing rock in favor of low- or no carbon igneous rock compositions . A presently preferred Phlego composition range is 40-55% silica, 5-15% CaO and 8-15% total alkalis (Na2O and K2O) with no significant carbon content (2% by weight or less) . However, expanding the range of usable rock types for Phlego cement would enhance its industrial scalability, maximizing the availability of suitable materials . Therefore, it would be an advance in the art to broaden the range of usable rock types for Phlego cement .

[0006] SUMMARY

[0007] This work addresses this need through advanced compositional optimization - where two or more rock types having non-Phlego compositions are strategically selected and mixed to achieve a Phlego composition for the resulting mixture . Such averaging can be visualized as schematically shown on FIGs . 1 and 2.

[0008] The example of FIG. 1 schematically shows the Streckeisen diagram, also known as the QAPF diagram. The diagram is a double-triangle (ternary) plot where eachcorner represents one of the major mineral groups . It is a classification diagram to classify igneous rocks based on their mineralogical composition. The name "QAPF" stands for the four major mineral groups used in the diagram:

[0009] Q: Quartz

[0010] A: Alkali feldspar

[0011] P : Plagioclase feldspar

[0012] F: Feldspathoid

[0013] The relative proportions of these mineral phases in a rock sample can be plotted within the different areas of the diagram to determine the rock' s classification.

[0014] The composition of the Phlego blend, defined as the "target" can be strategically obtained by considering the compositions of rocks surrounding this "target" region. By adopting a "mix and match" strategy, we can blend the surrounding rock compositions to achieve a desired compositional profile . This approach leverages the inherent variability and complementary compositions of neighboring raw materials within the diagram to tailor-make a blended material that aligns with the specific composition and properties of Phlego cement . In this example, the non-Phlego circle and triangle compositions are mixed according to the indicated percentages to provide the Phlego star composition .

[0015] FIG. 2 shows an example of compositional averaging on a TAS diagram. A TAS diagram classifies rock according to silica (S) and total alkali (TA) content . In this example, three non-Phlego circle compositions are mixed according to the indicated percentages to provide the Phlego star composition .

[0016] This strategy provides the following advantages :( 1 ) Tailored Material Properties :

[0017] By mixing and matching different rock compositions, we can create a cement blend with specific properties that are not readily available in carbonate rock alone;

[0018] (2 ) Resource Optimization:

[0019] Instead of solely searching for naturally occurring rocks to provide the exact target composition, this strategy increases the abundance by enabling the use of locally available materials from different geological scenarios . By combining the different raw materials in the right proportions, the desired target composition can be achieved. (3) Adaptability to Changing Conditions : this strategy allows for the adjustment of rock compositions to maintain performance standards . For example, the mixture can be recalibrated to optimize performance under the environment conditions, adapting to the particular demands of the application site .

[0020] (4 ) In general, Phlego cement provides important advantages of lower CO2 emissions, higher throughput, and lower transportation costs per ton of produced cement .

[0021] Commercial applications include cement, cementitious materials, and supplementary cementitious material

[0022] BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows an example of Phlego composition averaging on a QAPF diagram.

[0023] FIG. 2 shows an example of Phlego composition averaging on a TAS diagram.DETAILED DESCRIPTION

[0024] Mix-and-Match Strategy for Phlego Raw Material Optimization Carbonate rocks, including dolomite and limestone, comprise approximately 20-25% of all sedimentary rocks, with limestone being a subset and alone accounting for about 10-15% . In contrast, igneous rocks dominate ~95% of Earth' s crust, with calc-alkaline rocks forming a significant portion (~15- 18% ) . To optimize the composition of the targeted rock blend for Phlego, we refined its chemical balance through strategic volcanic rock mixing, adjusting SiO2, CaO and alkali levels (Na2O + K2O) to enhance availability while achieving optimal cementitious properties .

[0025] Compositional Window for Cementitious Material

[0026] This work relates to a raw meal formulated from a mix of compositionally diverse igneous rocks, optimized for structural performance and reactivity. The formulation is defined within specific compositional windows to

[0027] ensure predictable and scalable cementitious behavior :

[0028] • Silica (SiO2) : 40-55% Provides structural integrity and controlled reactivity.

[0029] • Calcium Oxide (CaO) : 5-15% Balances cementitious activity and durability.

[0030] • Total Alkalis (Na2O + K2O) : 8-15% Enhances activation potential while maintaining long-term stability.

[0031] These compositional windows allow for tailored mixing of various rock sources, including feldspathoid-rich and calc-alkaline rocks, while maintaining cementitious, workability, and durability properties .Identifying Key Compositions from QAPF & TAS

[0032] To achieve the target Phlego formulation, we leverage the QAPF (Quartz-Alkali Feldspar-Plagioclase-Foid) and TAS (Total Alkali-Silica) diagrams to strategically select and mix rock compositions within controlled chemical ranges .

[0033] FIG. 1 shows the QAPF Diagram (Quartz-Alkali Feldspar-Plagioclase-Foid) for Plutonic and Volcanic Rock Selection. The QAPF diagram categorizes rocks based on their feldspar, plagioclase, feldspathoid, and quartz proportions, impacting reactivity and durability as follows :

[0034] • SiO2: 40-50%, Alkali : 10-15%, CaO: 3-8% Feldspathoidrich, enhancing alkali activation.

[0035] • SiO2: 45-50%, Alkali : 6-12%, CaO: 8-15% Bridges feldspathoid and basaltic compositions, ensuring balance .

[0036] • SiO2: 48-53%, Alkali : 6-10%, CaO: 8-12% Optimized alkali-CaO balance for cementitious performance .

[0037] FIG. 2 shows the TAS Diagram (Total Alkali-Silica) for Volcanic Rock Selection. The TAS diagram categorizes volcanic rocks based on their SiO2vs . (Na2O + K20) content, ensuring a balanced mix for cementitious applications :

[0038] • SiO2: 45-55%, Alkali (Na2O + K20) : 10-15%, low CaO High feldspathoid content enhances reactivity, suitable for alkali activation from solid phases .

[0039] • SiO2: 50-55%, Alkali : 6-10%, CaO: 8-12% Balanced reactivity and stability, preventing excessive setting times .• SiO2: 55-65%, Alkali : 8-12%, CaO: <5% High alkali levels improve activation potential, but lower CaO requires compositional adjustments .

[0040] Mixing Compositions to Achieve the Desired Chemical Balance Once suitable compositions are identified, strategic mixing is performed to maintain the optimal balance of SiO2, alkalis, and CaO for Phlego' s cementitious formulation.

[0041] Key Adjustments in the Mix-and-Match Strategy

[0042] 1. Adjusting CaO Content for Cementitious Properties

[0043] o If CaO is too low ( feldspathoid-rich sources) , blend with limestone or intermediate volcanic compositions .

[0044] o If CaO is excessive, dilute with feldspathic materials to prevent hydration instability.

[0045] 2. Optimizing Alkali Content (Na2O + K2O) for Reactivity o High alkali improves reactivity but must be controlled to prevent expansion.

[0046] o Balance with lower-alkali components while maintaining activation potential .

[0047] 3. Silica Content Control for Structural Integrity

[0048] o Moderate SiO2levels enhance strength; excessive quartz reduces reactivity.

[0049] o Introduce feldspathoid or feldspar-rich sources to maintain the Si02-to-alkali ratio .

[0050] By strategically mixing volcanic and plutonic rocks from the TAS and QAPF categories, Phlego' s raw material formulation is optimized for cementitious performance while

[0051] ensuring geographic adaptability for sourcing raw materials .Establishing Compositional "Windows"

[0052] To obtain the targeted Phlego' s formulation, we establish compositional "windows" that guarantee consistent performance .

[0053] Target Compositional Windows

[0054] • Silica (SiO2) : 40-55% Ensures reactivity while maintaining structural integrity.

[0055] • Calcium Oxide (CaO) : 5-15% Prevents hydration instability while supporting cementitious strength. • Total Alkalis (Na2O + K2O) : 8-15% Optimizes activation while avoiding long-term instability.

[0056] Advantages of these ranges include :

[0057] 1. Balancing Workability, Durability, and Reactivity

[0058] o Too much silica decreases workability and reduces reactivity; too little weakens the structure . o Alkali content is key for activation but must be controlled for long-term stability.

[0059] 2. Ensuring Scalability and Raw Material Adaptability o Flexibility in obtaining these windows allows localized raw material sourcing while maintaining performance .

[0060] The following issues were considered to arrive at the preceding preferred composition ranges .

[0061] Excess silica (SiO2) in cement formulation is problematic because :1. Reduced Reactivity: Silica is inert and dilutes the active compounds, slowing down the setting and hardening process .

[0062] 2. Lower Strength Development : Too much silica reduces the formation of calcium silicate hydrate (C-S-H) , weakening the final strength of the cement .

[0063] 3. Unwanted Phases : Excess silica can form less reactive compounds, leading to shrinkage and durability issues .

[0064] 4. Compromised Workability: High silica content can make the mix dry, reducing ease of mixing, pumping, and placing the cement .

[0065] 5. Alkali-Silica Reaction (ASR) : Too much silica increases the risk of ASR, leading to expansion and cracking in the concrete .

[0066] Excess alkali (Na2<3 and K2O) in cement is problematic because :

[0067] 1. Alkali-Silica Reaction (ASR) : High alkali increases the risk of ASR, causing expansion and cracking.

[0068] 2. Weaker Strength: Too much alkali interferes with the formation of C-S-H, reducing strength.

[0069] 3. Workability Issues : It can decrease workability, making the mix harder to handle .

[0070] 4. Shrinkage and Cracking: Excess alkali can lead

[0071] to drying shrinkage and cracking.

[0072] Excess CaO (CaO) in cement formulation is not advisable because :1. Excessive Heat Generation: Too much CaO leads

[0073] to excessive heat release during hydration, which can cause thermal cracking in large concrete pours .

[0074] 2. Reduced Durability: High CaO can result in the formation of calcium hydroxide (Ca (OH)2) , which is soluble and weakens concrete, reducing its long-term durability .

[0075] 3. Increased Shrinkage : High CaO content can lead

[0076] to greater drying shrinkage, causing cracking and compromising the concrete ' s structural integrity.

[0077] The preceding considerations relate to providing the raw meal for Phlego cement production. For completeness, the remaining steps in Phlego cement production are firing the raw meal to provide a clinker, then grinding up the clinker and adding 0.5% to 2% gypsum by weight . This firing can be done at a temperature in the range of 900-1200 °C, for a residence time of 60 minutes or less . Calcination in 30 minutes has been achieved in an optimized process .

Claims

CLAIMS1. A method of making a raw meal for cement production, the method comprising:defining a target composition range of 40-55% by weight silica, 5-15% by weight CaO, 8-15% by weight total alkalis (Na2<0 and K2O) and 2% or less by weight total carbon content ;selecting two or more rock types, wherein each rock type has a composition outside the target composition range; andmixing the two or more rock types to provide a raw meal mixture, wherein the raw meal mixture has a composition within the target composition range .

2. A method of making a cement composition, the method comprisin :providing a raw meal according to the method of claim 1 ;firing the raw meal to provide the cement composition.3 . The method of claim 2 wherein a temperature of the firing is in a range from 900 °C to 1200 °C .

4. The method of claim 2, wherein a duration of the firing is in a range from 20 minutes to 60 minutes .

5. The method of claim 2, further comprising adding gypsum to the cement composition to provide a final composition,wherein a gypsum content of the final composition is 0.5% to 2% by weight .

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