Features of the fire assay method
The fire assay method is a classic analysis method that applies the principles and techniques of metallurgy to analytical chemistry, and is one of the oldest methods in analytical chemistry.
The fire assay method is to quantitatively determine the content of precious metals by adding flux to smelt ores and metallurgical products.
Features of The Fire Assay Method
Fire assay is not only an ancient means of enriching gold and silver, but also an important means of gold and silver analysis. Geology, mines, gold and silver smelters at home and abroad use it as the most reliable analysis method and widely used in production. Some countries have set this method as a standard method. Our country has also set it as a national standard method for the determination of gold in gold concentrates, copper concentrates, jewelry gold and alloy gold. With the development of science and technology, there are more and more new techniques for analyzing gold and silver, and analytical instruments are becoming more and more advanced. Compared with other methods, the fire assay method has a longer operating procedure and requires certain skills. There are many analysts try to use other analytical methods instead of fire assays.
However, the fire assay method is irreplaceable. For the determination of gold content in high-content gold raw materials or pure gold, its accuracy and accuracy are inferior to other direct determination methods. In the arbitration analysis of gold and silver content, fire Assay analysis can give convincing results for all parties in the dispute. This is because the fire assay has many unique advantages that other analytical methods do not have:
(1)Good sampling representativeness. Gold and silver are often present unevenly in the sample at the order of <g/t. The fire assay has a large sample size, generally 20-40g, and even samples up to 100g or more can be taken. Therefore, the representative of the sample is good. The sampling error is reduced to a minimum.
(2)Wide adaptability. It can adapt to almost all samples, from ore, gold concentrate to alloy gold, the fire assay method can accurately determine gold and silver, including those antimonites that cannot be solved by wet analysis. For the analysis of the main components of pure gold, the fire assay can also obtain satisfactory results. Except for very few samples, this method can be adapted to almost all minerals.
(3)The enrichment efficiency is high, reaching more than ten thousand times. A small amount of gold and silver can be quantitatively enriched from tens of grams of samples containing a large amount of matrix elements into the test gold button. Even if the micrograms of gold and silver are enriched, the loss Very small,-generally only a few percent. Due to the simple composition of the compound granule (or enrichment slag), it is beneficial to use various test methods to determine in the future.
(4)The analysis results are reliable and accurate. South African Rand Company's routine analysis of pure gold (>99.9%), 74 analysis results of the same sample, the standard deviation (S) 0.0058%. The S of 10 analysis results of similar domestic products is also about 0.005%. Over the years, some scholars at home and abroad have tried to completely replace the fire assay with new wet chemical analysis or instrumental analysis, but they have not succeeded so far. Werbicki et al. compared the three analytical methods of Au in solution-AAS, ICP-AES, and the assay method, and gave the standard deviation S of each method analyzed by 18 laboratories. The result is that the ICP-AES and AAS methods are basic Consistent, but all slightly worse than the trial gold method Wall pointed out that the fire assay method is suitable for samples with a gold content of <1μg~1g, and its accuracy and precision are better than other instrumental analysis.