Method for determination of silica content in microsilica powder

Microsilica - Determination method for silica content in silica fume

Under normal circumstances, the detection of silica content in micro-silica powder silica ash is usually detected by hydrofluoric acid gravimetric method. Before detecting the content of silica, the firing loss must first be detected, and then the content of silica can be detected.

1. Detection and analysis of micro-silica fume burning loss:

The silica powder sample of 0.5g was accurately weighed, dried at 105~110℃, added to the platinum crucible, and then burned at 950~1000℃ for 45min, and then the crucible was placed in the dry and cooled to room temperature, and weighed. Repeat until the weight is constant.

Burn loss =(M-M1)/m ×100

Where: m1 -- mass of sample before burning, g;

m -- mass of burned sample, g;

2, hydrofluoric acid gravimetric test of micro-silica powder silica content:

Accurately weigh the 0.25g sample after measuring the firing loss, moisten it with a small amount of water, add 4-5 drops of sulfuric acid (1+1) and 5-7ml hydrofluoric acid, and put it on the electric plate or electric furnace at low temperature to heat volatilize, and cool it 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 increase the temperature until the white smoke of sulfur trioxide is completely escaped, and the platinum crucible is burned in a high temperature furnace at 900℃ for 30min. Remove, cool to room temperature in a dryer and weigh. Repeat until the weight is constant.

The mass percentage of SiO2 in the sample is calculated according to the following formula:

Silica SiO2=(M-M1)/m x 100

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

m 2 -- mass of residue and crucible, g;

m -- mass of sample, g;