GB/T 6730.27-2017 in English

National Standard of the People's Republic of China

Determination of fluorine content in iron ore - Lanthanum alizarin complex spectrophotometry

Standard background and technological evolution

GB/T 6730.27-2017 is the 27th part of the GB/T 6730 standard system, mainly used for the determination of fluorine content in iron ore and its products. This standard replaces the old standard GB/T 6730.27-1986. The main technical changes include:

• Updated the standard name and scope
• Added chapters such as warnings and normative references
• Specified the specific requirements for sampling and sample preparation
• Optimized the expression of sample quantity and weighing accuracy

Technical principles and methods

This standard adopts the lanthanum-alizarin complex spectrophotometry method, using fluorine to react with lanthanum and alizarin to form a blue ternary complex, and measuring the absorbance at a wavelength of 620 nm. The specific steps are as follows:

1. Sample decomposition: The sample is distilled with perchloric acid and phosphoric acid at high temperature to separate fluorine from other elements.
2. Color reaction: Take part of the distillate and add lanthanum-alizarin complexing agent in acetone medium to form a blue complex.
3. Spectrophotometry: The absorbance is measured by a spectrophotometer and compared with a standard curve to determine the fluorine content.

Instrument Specifications

The main instruments used in the analysis include:

• Steam distillation apparatus: used for high-temperature decomposition of the sample.
• Spectrophotometer: The wavelength range covers 620 nm.
• Muffle furnace: used for sample pretreatment.

Comparative Analysis of Standards

Implementation suggestions