What’s the difference between basalt mineral wool and slag mineral wool

 Analysis: The chemical composition of blast furnace slag is that the SiO2+Al2O3+CaO+MgO content is as high as 90% to 95%, and the Fe2O3+FeO content is less than 1%, while that of basalt and dolerite is SiO2+Al2O3+CaO+ The MgO content 77% to 83%, which is more than 10% lower than that of blast furnace slag. The content of Fe2O3+ FeO is about 11% on average, and it can reach 17% at the highest. From this, the acidity coefficient MK of the basalt mineral wool board is calculated to be 1.5 or even more than 2.0, and the acidity coefficient MK of the slag mineral wool board is about 1.2.

2 The difference in water resistance between basalt mineral wool board and slag mineral wool board

The crystallization zone of basalt mineral wool board is CS-C2AS-C2S (wollastonite-aluminum beryl-calcium feldspar). All of them have no hydraulic characteristics, and the changes are very small after water exposure, making the basalt mineral wool board have good water resistance. The crystallization zone of the slag mineralwool board is CS-C2AS-CAS2 (wollastonite-aluminum cristobalite-dicalcium silicate), and the dicalcium silicate produces hydration reaction with water in the course of its production with increasing temperature, so that the stability of slag wool fibers decreasing in a humid environment;

Basalt mineral wool board’s PH value is less than 4, which belongs to mineral fiber with particularly stable water resistance. Slag wool is generally more than 5, even more than 6, and its water resistance can only be moderately stable or unstable.

3 The comparison in thermal conductivity performance

Both basalt wool board and slag mineral wool board have good thermal insulation performance. When the working temperature exceeds 675°C, the cooling process of slag wool will be slow, which causes the internal structural conversion density to decrease from 3.28 to 2.97, and the volume expands by about 10%, making the slag mineral wool board powdered and disintegrated, but basalt mineral wool board does not have this conversion, the use of temperature is up to 760 °C above, the softening temperature is 900 ~ 1000 °C.

4 The difference in corrosion resistance

One of the main functions of the blast furnace is desulfurization to prevent iron brittleness in the process of use. These removed sulfur remain in the form of CaS in the blast furnace slag and then enter the slag wool. The content is about 5%. When the slag mineral wool board is used in a high-humidity environment, the CaS will decompose into Ca(OH)2 and H2S. Ca(OH)2 makes the water alkaline and further reduces the water resistance of the slag cotton. H2S gas can be dissolved in water to produce hydrosulfuric acid, which will cause corrosion when it comes into contact with metal. The basalt mineral wool board uses basalt or diabase as a raw material, there is no sulfur source, so no corrosion will occur.