When decomposing iron ore, why should it be carried out at low temperature?
Because the iron ore inside the FeCl3, Yi Shenghua, most of the more than 100 degrees Celsius will evaporate into the air, so it is low temperature decomposition.
The decomposition of iron ore, in practical applications, is based on the characteristics of the ores, the requirements of the analytical items, and the separation of interfering elements. Acid decomposition and alkali melting are usually employed.
At present, it is more common to use alkali fusion to decompose sample. Sodium carbonate, sodium hydroxide, sodium hydroxide, potassium hydroxide and sodium hydroxide and sodium carbonate with commonly used fluxes (2:1) mixed flux etc.. The melting can be carried out in a silver crucible, a Nickel Crucible, a high aluminium crucible or a graphite crucible. Also useful sodium peroxide in the Nickel Crucible semi molten.Since iron ore contains a large amount of iron, it can be damaged by melting directly in the platinum crucible with sodium carbonate, and platinum also affects the determination of iron, so it is seldom used.For iron ores containing sulfides and organic compounds, the sample should be burned at 500-600 degrees C to remove sulfur and organic matter, and then decomposed with hydrochloric acid and added a small amount of nitric acid to decompose the sample completely. The presence of nitric acid affects the determination of iron and can be removed by evaporation with hydrochloric acid.
The commonly used acid decomposition method is as follows:(1) hydrochloric acid decomposition of iron ore can generally be heated by hydrochloric acid decomposition, iron silicate soluble in hydrochloric acid, can add a little hydrofluoric acid or ammonium fluoride, the sample is completely decomposed. The dissolution rate of magnetite is very slow, add a few drops of stannous chloride solution, the decomposition speed is.(2) sulfuric acid hydrofluoric acid decomposition sample, in the platinum crucible and the plastic crucible, adds 1:1 sulfuric acid 10 drops, hydrofluoric acid 4-5ml, the low temperature heats up, when will emit three oxidation two sulfur white smoke, extracts with hydrochloric acid.(3) when sulfuric acid or sulfur phosphorus mixed acid (1:2) dissolves, the ore needs to be heated until the water is completely evaporated, and the white smoke of three sulfur trioxide is added, and then heated for several minutes. But the heating time should not be too long to prevent the formation of pyrophosphate.
