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Coal contains many harmful elements, which will enter the atmosphere in the form of gas, dust or powder, or infiltrate the soil with rain, causing environmental pollution. Therefore, in addition to daily combustion characteristics of coal used for power generation, it is also necessary to determine the content of organic and inorganic elements.

There are many methods for the determination of these elements, the traditional wet digestion process is time-consuming with high blank value and the volatile elements such as mercury, arsenic, and selenium are easily lost, resulting in a large deviation in the measurement results. Microwave digestion technology has developed rapidly in recent years, and it is a fast and efficient method of dissolving samples, which uses a sealed vessel for digestion to avoid volatilization during the dissolution of volatile trace elements. Welso used microwave technology to digest the coal samples, and achieved good digestion results. Please refer to following experiment process.

Sample:

Gasified Coal

Fine Coal

Coarse Coal

Experimental reagents and dosage (per digestion vessel ):

● AR nitric acid: 2 ml

● AR hydrochloric acid: 6 ml

● Ar hydrofluoric acid: 2 ml

Experimental equipment:

●WMD800

●Analytical balances

●10ml pipette

Sample Handling Steps:

●Weigh 0.1 g of sample (accurate to 0.1 mg), place it in a microwave digestion inner tank, and add 2 ml of nitric acid solution, 6 ml of hydrochloric acid and 2 ml of hydrofluoric acid solution. Let stand for about 10 minutes to allow the sample to come into full contact with the digestion solution.

●Seal the can, mix well, and load it into the microwave digestion instrument, and carry out microwave digestion according to the digestion procedure on the following page.

Digestion Methods:

Digestion Results

Gasified Coal

Fine Coal

Coarse Coal

Gasified Coal：Large particles remain after digestion

Fine Coal：Almost no digestion

Coarse Coal: Solid particles in the suspensions in the solution

The WMD800 microwave digestion system is a new product launched by Welso in 2019, which has been newly designed and upgraded with higher performance and protection system, and is welcomed by users around the world. We also have high-throughput WMD1200R, WMD1800R, and WMD4000, and if you need to know more about each device, you can download the microwave digestion brochure from our website.