Method for determining mercury and arsenic in briquette coal based on hydrothermal synthesis reaction kettle digestion briquette coal-atomic fluorescence spectrometry

Abstract

The invention relates to the field of liquid phase chemistry, in particular to a method for determining mercury and arsenic in briquette coal based on hydrothermal synthesis reaction kettle digestion briquette coal-atomic fluorescence spectrometry, which comprises the following steps: adding a certain amount of briquette coal and a proper amount of mixed acid into a polytetrafluoroethylene sealing tank which is subjected to soaking, cleaning and preheating pretreatment, and pre-digesting until gas is released and the reaction tends to be mild; covering, putting into a stainless steel sleeve, sealing, putting into an electrothermal blowing dry box, carrying out closed heating digestion, and then carrying out acid removal and constant volume operation, so as to obtain a solution to be detected; and additionally preparing standard series solutions of mercury and arsenic elements, drawing a standard curve, testing the obtained digestion solution to be detected by using an atomic fluorescence spectrometer to obtain fluorescence intensity, and converting through the standard curve to obtain the content of corresponding elements in the briquette coal. The method can accurately measure the content of volatile trace elements represented by mercury and arsenic in the briquette coal.

Description

technical field [0001] The invention relates to the field of liquid phase chemistry, in particular to a method for determining mercury and arsenic in briquette based on hydrothermal synthesis reactor digestion of briquette-atomic fluorescence spectrometry. Background technique [0002] Coal is a complex geological product consisting of various organic and inorganic minerals. The briquette is made of coal as the base material and is compounded by adding a variety of different types of binders (such as coal tar, coal tar, starch, humic acid, biomass, etc.), which is more complex than the chemical composition of raw coal itself. There are dozens of harmful or potentially harmful trace elements, such as Cr, Cl, Pb, Hg, Se, As, etc. Compared with the major harmful elements, the content of trace elements is extremely low, the occurrence forms are complex and diverse, and the toxicity is high. In the process of thermal processing and utilization such as pyrolysis and combustion, i...

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Problems solved by technology

Among them, the electric hot plate atmospheric pressure open digestion method directly digests the coal sample with mixed acid in an open container. Cross-infection, if it is used for the digestion of briquette samples, due to the complexity and particularity of the briquette composition, the compatibility between the briquette and the mixed acid is not good, and the temperature and pressure cannot reach the ideal state, and the sample is difficult to completely dissolve, resulting in the determination The result is seriously distorted, the detection limit of the method is high, and the amount of acid is large

The microwave digestion method is advanced and reliable, but the cost of equipment is high and it is difficult to achieve popularization

If it is used for the digestion of briquette samples, due to the weakening of the interaction between the binder and the coal particles in the briquette and the action of the acid, a large amount of acid is used to achieve a clear and transparent digestion effect, and it takes a long time to catch the acid in the later stage, which cannot guarantee that the volatile elements will not be removed. Escaping, acid decomposition is easy to produce a large amount of nitride gas, causing the deformation of the digestion tank. Secondly, the organic binder in the briquette makes the volatile content higher, and the volume of the fluid in the closed digestion tank expands during digestion, and the pressure increases sharply. , there is a potential danger of causing the reaction to go out of control and cause the digestion tank to burst

In the ashing-digestion method, the test is ashed and then digested with mixed acid. The ashing process is cumbersome, and most of the organic binders (starch, biomass, coal tar) in the briquettes have a low decomposition temperature, and volatile residues are easily Minor elements (such as Hg, As) escape with organic volatiles, resulting in low measurement results

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