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Analysis of gold with chemicals
Directly to the process of gold mining is necessary to take a number of deep research . One of them – a test of the mineral content in the ore is enriched . Process detailed analysis of the presence of metal in the rock samples taken from the soil study area – is a very important step towards the confirmation of gold reserves , as well as the support of large-scale activities in their production .
One of the forms of assessment content – is a laboratory analysis of rock samples . To date, there are many different methods to do this, but they all depend on the desired end result. Some of the best approaches – the use of modern equipment, which is based on the polarization beam techniques and electron microscopy. They allow the analysis of the whole structure , the structure and mineralogy of certain minerals based on their samples.
In order to obtain detailed information about the content of metal in the rock is necessary to the modern analytical techniques – techniques of testing fusion , atomic absorption spectrometry (Atomic Absorption Spectrometry – AAS) , etc.
Apart from them , in this case may find its use and much simpler methods of analysis, the essence of which is the use of chemical solutions which allow to determine the presence of gold in the rock -tested her samples. This approach is very easy, but nevertheless , is quite sensitive to the content of the metal.
For the analysis of metal content in the rock sample must take the following steps .
– Prepare – rock samples from the survey area , weighing approximately 60 g and granulate them to about 200 mesh (0.074 mm).
Prepare – distilled water in a conical flask.
– Using the measuring cup , make a chemical solution of aqua regia : a mixture of 3 parts of hydrochloric acid (HCl) and 1 part nitric HNO3. The solution volume should be 4-5 times the volume of the samples.
– Slowly pour into a container with distilled water with aqua regia . The ratio should be 1 to 1 . Peculiar smell will let you know that the aqua regia sufficient to react .
Then aqua regia – heated at a temperature of 85-90 degrees Celsius. Place a piece of the rock in a container and then wait at least 30 minutes.
Reaction formula of gold dissolution in aqua regia
Au + 3HNO3 4HCl = HAuCl4 + + 3NO2 + 3H2O.
After the rain stopped cooling the reaction of aqua regia and water and sediment deposition . Filter the precipitate and then using a tea strainer and napkins. So you separate the precipitate from the solution .
In order to verify the presence of gold in the rock sample , add the precipitate prepared in advance a special solution, for example , 5% tin chloride (SnCl2), diluted with 95 % hydrochloric acid (HCl). Tin chloride – this is a very sensitive reagent allows one to identify the amount of gold to 10 parts per billion .
If the drop of solution ( stannous chloride ) will turn the purple color, this indicates that the sample contains gold.