Updated on 17/Jul--Let's continue to talk about the cupellation procedure in fire assay analysis

2.4.2 -After the cupellation is completed, you should wait for the furnace temperature to cool down before opening the furnace door. Otherwise, at the moment of opening, the above-mentioned blooms that seriously affect the measurement will appear.

Experiments show that the gold-silver ratio of different concentrations will have different loss rates under the same cupellation conditions. The higher the silver content, the more serious the loss of total gold and silver.

2.5 Influence of platinum group elements on gold

When the platinum group metal contains platinum group metals, it cannot be removed by cupellation. The presence of platinum group metal metals may make the combined particles dark after the cupellation, and not smooth after flaking. In severe cases, it may be in the process of flaking There are burrs and bifurcations, which have a serious impact on the measurement. For the Pd element in the combined gold, it can be separated from the gold by gold separation (the gold separation solution is red), which does not affect the measurement result. However, other platinum group metals are not easy to separate, resulting in high gold. We can roughly judge the existence of platinum group metals through the gold roll. If there is black on the gold roll, it indicates that the platinum group metal exists. At this time, the result of the fire test method will be wrong.

For the case where the Pd element is contained in the gold, we have our own method. Of course, this method has a large loss rate of gold and silver, but in order to meet and prove that we are responsible to the customer, we will ask the customer to observe it on site to prove that it does contain Pd element.

2 types of cupel normally

There are two types of cupel for analysis by fire assay, one is made of animal ashes and the other is made of magnesia. We generally use bone ash cupel, but since animal ashes are getting fewer and fewer, it is a trend to use magnesia cupels.(In fact, magnesia cupel are more accurate than bone ash cupel.