SU1357843A1 - Method of determining free silicon dioxide in coal and rock dust - Google Patents

Abstract

The invention relates to methods used in analytical chemistry, and allows for improved accuracy and selectivity of determination. The method includes ashing of the sample, fusion, dissolution, the introduction of ammonium molybdate, a reducing agent - citric acid, irradiation with ultraviolet light and the subsequent measurement of optical density. Accuracy of determination is 2-8%. The 5-fold excesses of arsenic and phosphorus do not interfere with the determination. Table 2. 00 SP 00 4 OE

Description

1135

This invention relates to analytical chemistry, and specifically to methods for studying coal and rock dust.

The purpose of the invention is to improve the accuracy and selectivity of the determination.

Example. 10 mg of coal dust are ash at 650 ° C. To a cooled crucible, 3.5 ml of smoothly are poured (50 g of potassium carbonate and 50 g of potassium chloride in 300 ml of wax. The crucible is placed in a drying oven at 200 ° C to evaporate the liquid and then placed in a muffle furnace for 7 minutes. Heated to 850 ° C. After cooling, 10 ml of a 5% sodium carbonate solution are added to the crucible and heated to complete dissolution of the melt. It is filtered through an ash filter into a 50 ml volumetric flask. The crucible is washed 3 times with water under heating and the washed water is the same filter. The solution is neutralized with 7 ml of 1N sulfuric acid and after cooling the volume is adjusted to 50 ml.

For the analysis, take 2 ml of this solution, dilute to 20 ml, pour in 1 ml of a 7.5% pure sulfuric acid solution of ammonium molybdate and after 5 minutes 5 ml of a 5% aqueous solution of citric acid and: 5 ml. 10 n, sulfuric acid. The solution is irradiated for

5min - UV illuminator VIO-1 in quartz cuvettes.x. Distance from the lamp to the irradiated solution

6cm ..

five

At the end of the test, the optical density of the solution is measured on a spectrophotometer with a wavelength of 815 nm.

A sample of the sample is 10; 7 μg of silica (10.0 μg per sample). A known method is found 8s2 µg. The accuracy of the determination according to the method 79S54% known, g, the proposed 91.59%, Relative -.- LN standard deviation according to the known method 20.63%, according to the proposed method 8.09%.

Table 1 presents experimental data 5 showing that the presence of phosphates in triplicate: the number does not mark the definition

In tab. Figure 2 presents experimental data showing that the presence of five -; rags, 1x quantities of mice overstates fire results, the Formula, and 3 about the same

A method for determining free silica in coal and rock dust, including its ashing, melting, and melting. the introduction of ammonium molybdate g, a reducing agent, and 0 subsequent measurement (the measurement of optical density, which is based on accuracy and selectivity, is determined as a reducing agent from J5 ammonium acid and reduction carried out under irradiation with ultraviolet light.

0

five

T a b

and a

table 2

Claims (1)

Formula and Sample 25 A method for determining free silicon dioxide in coal and rock dust, including its ashing, fusion, dissolution, introduction of ammonium molybdate, a reducing agent, and 30 subsequent measurement of optical density, with the fact that, with the aim of increasing the accuracy and selectivity of determination, they use 35. Citric acid and reduction are carried out by irradiation with ultraviolet light.