Calcium magnesium silicate ore will be generated yearly as stripped material associated with wollastonite mining operations, however its variety of applications means that this material is economic rather than waste.
Synthetic Slag Conditioning
The steel industry uses synthetic slag formulations to control temperature, oxidation and waste removal during the smelting process. Products like High Calcium Quicklime and Silica sand can be partially replaced with wollastonite and Dolomitic Quicklime partially replaced with diopside. This lowers the melting point and requires less flux to achieve desired viscosity, while reducing the amount of CO2 normally released by the lime-based ingredients.
Industrial Cement Production
The production of conventional cement is very energy intensive and releases large amounts of CO2. Wollastonite and the surrounding calcium magnesium silicate are non-CO2 emitting, single sources of calcium and silicone oxides. Bench trial results showed the following benefits;
Reduced CO2: Early trials show a 30% substitution of wollastonite ore results in combined calcination and energy related CO2 reduction of 24%.
Energy Efficient: Cement clinker made with 44% wollastonite in a coal-fired process required less fuel because of lower reaction temperatures and resulted in an additional 44 kg CO2 savings per ton of cement.
Greater Performance: Experimental analyses on strength, texture and free lime for wollastonite-based cement showed better results than conventional samples.
Greater Strength: Natural wollastonite micro-fibres have a high stiffness and increases the level of flexural strength and improved load-deflection response when incorporated into cement and cement-silica fume matrices. The colourless, hydrophobic and small wollastonite fibers results in easier colour matching, greater freeze-thaw resistance, and suitability for thin set mortars and coatings.
Increased Durability: Greater mechanical resistance and chloride tolerance reduces corrosion on reinforcing steel and increases product lifetime. Thermal resistance makes wollastonite suitable for high heat applications and increases burn through time.
Lower Cost: Natural wollastonite fibres provide a relatively low-cost alternative to other reinforcement fibres for cement systems by providing multiple congruent benefits not often found with conventional additives.