How to Analysis the Silicon content in Rare Earth Ferro Silicon Magnesium

What is Ferro Silicon Magnesium (FeSiMg)?

Ferro silicon magnesium (FeSiMg), also known as nodularizing agent is a kind of alloying additive.  

Ferro Silicon Magnesium FeSiMg ferro silicon mangensium price

How to Analysis the Si Content in FeSiMg

Generally, the silicon content of ferrosilicon nodulizing agent is between 35% and 47%. How to quickly and accurately detect the silicon content in rare earth magnesium ferrosilicon alloy is of extremely important significance. The main methods for determining the silicon content in rare earth ferro silicon magnesium alloys include gravimetric method, spectrophotometry and acid-base titration. Through the discussion and comparison of the analysis methods of silicon content in rare earth ferro silicon magnesium alloys, the reaction mechanism, reagents, analysis methods and other aspects are studied.

The results show that the potassium fluorosilicate volumetric method has accurate results, high reproducibility, short analysis time, and can quickly and accurately analyze the silicon content in rare earth magnesium master alloys.

Test device

The test device used in this article is an air extraction filter device.

Principles of chemical reactions

The standard sample is dissolved with nitric acid and hydrofluoric acid to convert silicon into the form of fluorosilicic acid. In the presence of excess K+, fluorosilicone complex ions will form potassium fluorosilicate precipitates, and then the precipitates are hydrolyzed with boiling water to produce silicon. The equivalent amount of hydrofluoric acid is burned. The hydrofluoric acid is titrated with a standard acid and alkali solution. The chemical reaction formula is as follows:




Laboratory calibration method of sodium hydroxide solution

Method 1: Calibrate with potassium hydrogen phthalate. Weigh 2.000 g of potassium hydrogen phthalate solid powder dried at 105-110 °C and place it in a 250 mL Erlenmeyer flask. Add 100 mL of sub-boiling water to dissolve it. Add 5 drops of mixed indicator and use hydrogen Titrate the sodium oxide solution until the solution turns bright purple, and record the volume V of the standard solution consumed. Calculate the concentration of sodium hydroxide solution according to the following calculation formula.


T is the titer of sodium hydroxide solution to silicon, in g/ml; X is the silicon content in the ferrosilicon standard sample; The volume of sodium oxide solution, in ml.

Analytical method

Weigh 0. 100 0 g sample (accurate to 0. 000 2 g), place the sample in a 400 mL polytetrafluoroethylene beaker, add 10 mL of HNOs, dropwise add 5 mL of HF, and stir with a plastic rod Completely dissolve the sample.

Purge the cup wall with 15 mL of water, add 20 mL of KNO3 solution while stirring, continue stirring for 0.5 min, leave it for 20 min, and place it in cold water or ice water. Use medium-speed quantitative filter paper to filter the test solution and the sediment on the air extraction filtration device. Wash the beaker and the sediment three times each with KNO3 washing solution, each time not exceeding 5 mL. Move the sediment and the filter paper to the original beaker, add KF protective solution 15 mL, add 10 drops of mixed indicator, neutralize the residual acid with sodium hydroxide solution, carefully scrub the wall of the cup while neutralizing and mash the filter paper into a paste, when neutralized with sodium hydroxide solution until the solution When a bright purple color appears, for example, quickly add 200 mL of boiling water, immediately titrate with sodium hydroxide standard solution, add 5 drops of indicator when the end point is lavender, and continue titrating until a bright purple color appears.

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