Dicalcium Silicate Production via Mineralizing Agents
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Solution Overview
Problem
Conventional processes for producing dicalcium silicate as a hydraulic binder are energy-consuming and require multiple thermal treatment stages, with limitations such as slow reaction rates and incompatibility with calcium carbonate.
Innovation Solution
A process involving a mixture of calcium carbonate and silicon dioxide with an inorganic alkali or alkaline earth metal salt as a mineralizing agent, reacted in a controlled CO2 atmosphere at elevated temperatures to produce dicalcium silicate with low unreacted material and carbon content, optimizing the molar ratio and reaction conditions for efficient energy use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional rotary tube furnace process is used to produce dicalcium silicate, then dicalcium silicate can be produced as a hydraulic binder, but the process is energy-consuming and requires high firing temperatures (1250°C)
Solution Approach 1:
The patent changes the temperature parameter from conventional high firing (1250°C) to lower temperature range (900-1100°C) by introducing mineralizing agents that catalyze the formation of dicalcium silicate at reduced temperatures, thereby decreasing energy consumption while maintaining product quality
Solution Approach 2:
The patent introduces mineralizing agents (such as alkali metal salts or alkaline earth metal salts) as intermediaries that facilitate the chemical reaction between calcium carbonate and silicon dioxide at lower temperatures, acting as catalysts to enable the formation of dicalcium silicate without requiring conventional high-energy firing processes
2Reliability
If multiple thermal treatment stages (hydrothermal treatment + firing) are used, then dicalcium silicate can be produced from calcium carbonate and silicon dioxide, but the process complexity increases and reaction slowness persists
Solution Approach 1:
The patent merges the hydrothermal treatment stage and the firing stage into a single thermal treatment process. By adding mineralizing agents to the starting material mixture before one-stage heating, the process combines what were previously separate sequential operations into one integrated step, reducing process complexity while maintaining effective conversion
Solution Approach 2:
The patent performs preliminary action by pre-mixing mineralizing agents with the calcium carbonate and silicon dioxide starting materials before thermal treatment. This preliminary preparation ensures that the catalytic components are already in position to facilitate the reaction during the single heating stage, eliminating the need for separate hydrothermal and firing stages
3Reliability
If conventional process is used, then dicalcium silicate can be produced, but calcium carbonate cannot be used directly and reaction rate is slow
Solution Approach 1:
The patent introduces mineralizing agents as intermediary substances that catalyze the reaction between calcium carbonate and silicon dioxide. These agents lower the activation energy barrier and significantly increase the reaction rate, enabling direct use of calcium carbonate as a starting material without requiring slow conventional thermal treatment processes
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method enables energy-efficient production of dicalcium silicate with high yields of α′L- and β-C2S, reducing energy consumption and thermal stress, while allowing for the use of calcium carbonate and achieving low total carbon content in the product.
Implementation Method 1
The starting material is reacted with the mineralizing agent in a gas atmosphere having a CO2 partial pressure of from 0.05 MPa to 0.2 MPa at a temperature of from 900° C. to 1100° C. so as to obtain a dicalcium silicate product
Data Source
AI summary
A process for preparing dicalcium silicate includes providing a starting material comprising calcium carbonate (CaCO3) and silicon dioxide (SiO2), wherein a molar ratio of calcium:silicon (C:S) is from 1.5:1 to 2.5:1. At least one of an inorganic alkali metal salt and an alkaline earth metal salt is added as a mineralizing agent to the starting material in an amount of from 0.5 wt.-% to 20 wt.-%, based on a total weight of the starting material. The starting material is reacted with the mineralizing agent in a gas atmosphere having a CO2 partial pressure of from 0.05 MPa to 0.2 MPa at a temperature of from 900° C. to 1100° C. so as to obtain a dicalcium silicate product. The dicalcium silicate product comprises a content of an unreacted starting material of <5 wt.-% and a total carbon content of <1.5 wt.-%, each based on a weight of the dicalcium silicate product.