Method for the detection of silica content in silica fume

Methods for the detection and testing of silica content in silica fume

In general, the detection and laboratory test of silica content in silica fume is usually carried out by hydrofluoric acid gravimetric method. Before the silica content can be detected, the loss on ignition must be detected before the silica content can be detected.

1. Detection and testing of silica fume loss on ignition:

Accurately weigh 0.5g of silica powder sample, dry it at 105~110 °C, add it to a platinum crucible, and then burn it at 950~1000 °C for 45min, and then put the crucible in a dry place to cool to room temperature and weigh it. And so on until the weight is constant.

Loss on ignition = (m-m1)/m ×100

where: m1 - the mass of the specimen before burning, g;

m—— mass of the specimen after burning, g;

2. Hydrofluoric acid gravimetric method for detection and testing of silica content in silica fume silica fume:

Accurately weigh 0.25g of the sample after measuring the loss on burning, wet it with a small amount of water, add 4~5 drops of sulfuric acid (1+1) and 5~7mL hydrofluoric acid, heat and volatilize it at low temperature on an electric hot plate or electric stove, and remove it to cool when it is nearly dry. Add 2~3 drops of sulfuric acid (1+1) and 3~4mL hydrofluoric acid, continue to heat and volatilize until dry, and then raise the temperature until the sulfur trioxide white smoke is completely exhausted, put the platinum crucible into a high-temperature furnace and burn it at a temperature of 900 °C for 30min. Remove, cool to room temperature in a desiccator and weigh. And so on until the weight is constant.

The mass percentage of SiO2 silica in the sample is calculated as follows:

SiO2 = (m-m1)/m ×100

Where: m1 - the mass of the specimen and crucible after burning, g;

m 2 – mass of residue and crucible, g;

m - the mass of the specimen, g;