KR101271192B1 - Analytical method on trace element of rock samples by acid digestion method with fused glass beads - Google Patents

Abstract

Disclosed is a method for analyzing trace elements of rock samples using glass spheres that can shorten the wet pretreatment time as well as the accuracy of analysis of insoluble elements.
The trace element analysis method of the rock sample according to the present invention comprises the steps of (a) mixing the rock sample and the flux to form a glass sphere; (b) reacting the glass spheres with a mixed acid solution to primary acid decomposition; (c) secondary acid decomposition by adding HClO ₄ to the primary acid-decomposed mixture; (d) diluting the secondary acid decomposed mixture with an aqueous HNO ₃ solution; And (e) measuring the elements contained in the diluted mixture.

Description

ANALYTICAL METHOD ON TRACE ELEMENT OF ROCK SAMPLES BY ACID DIGESTION METHOD WITH FUSED GLASS BEADS

The present invention relates to a method for analyzing trace elements of rock samples, and more particularly, to a wet pretreatment using glass spheres that can shorten the process time and the accuracy of analysis of insoluble elements by performing wet pretreatment using glass spheres. It relates to a trace element analysis method of a rock sample containing.

In order to analyze trace elements in rocks, it is usually necessary to make solid samples in solution. In addition, the method of dissolving an appropriate rock sample may vary according to an analysis method of trace elements.

The method of dissolving the solid sample is classified into a beaker-open beaker method, a high pressure bomb, an alkali melting method and a microwave digestion method.

On the other hand, the inductively coupled plasma mass spectrometer (ICP-MS), which is commonly used to measure the elements contained in rock samples, has a very low analysis limit (more than 100 times compared to spectroscopic method). Since they can be measured simultaneously in a short time (usually 1-2 minutes), they are very useful for measuring trace elements in rocks and minerals. In particular, it has excellent analytical sensitivity to the rare earth elements which are considered to be geologically important, and can measure the concentration of meteorites without chemical separation and concentration. Therefore, it can be a good analysis method for comparing the trace element analysis results according to the rock dissolution method.

However, inductively coupled plasma mass spectrometers are limited in the amount of dissolved solids in the dissolved sample, the sensitivity decreases or increases when the amount of dissolved solids is large, and there are polyatomic interferences formed by the reagents used during the dissolution process. Consideration is needed.

In addition, the inductively coupled plasma mass spectrometer is for simultaneous multi-element analysis, so when the sample is made into a solution by one dissolution method to analyze several elements, the accuracy and precision of the result may be affected depending on the element to be analyzed.

At this time, in the case of dissolution by the beaker-heating plate method and the acid decomposition method by the microwave oven method, when the elements such as Zr and Hf are concentrated in insoluble minerals such as zircon, the measured concentration is due to insufficient dissolution of the minerals. Appears low.

When dissolved using alkali melting to dissolve insoluble minerals, the high temperature causes the loss of a significant portion of volatile elements such as Pb, Cu, and Rb, and the dilution ratio due to the increase of the total dissolved solids due to the mixing of rock samples and fluxes. This increases to approximately 1,6,600, which may adversely affect the accuracy of analysis of low concentration rare earth elements.

In particular, Zr, Y, Hf, Nb, and Ta among the trace elements are important elements used in the analysis of the Earth's tide with other non-flowable elements. Among them, Zr and Hf are insoluble minerals such as zircons that concentrate them in the rock. There is a problem that it is not completely dissolved by acid decomposition.

Meanwhile, in the case of the beaker-heating plate method, which is a general pretreatment method for analyzing trace elements of rock samples, there is a problem that the total time required for pretreatment takes about 4.5 to 5 days.

An object of the present invention is to analyze the trace element of the rock sample by the acid decomposition method using a glass bead, to improve the analysis accuracy of the insoluble element, and to reduce the wet pretreatment time to analyze the trace element of the rock sample To provide.

The trace element analysis method of the rock sample by wet pretreatment using the glass sphere according to an embodiment of the present invention for achieving the above object comprises the steps of: (a) mixing the rock sample and the flux to form a glass sphere; (b) reacting the glass spheres with a mixed acid solution to primary acid decomposition; (c) secondary acid decomposition by adding HClO ₄ to the primary acid-decomposed mixture; (d) diluting the secondary acid decomposed mixture with an aqueous HNO ₃ solution; And (e) measuring the elements contained in the diluted mixture.

The trace element analysis method of the rock sample according to the present invention performs a dilution ratio of the rock sample and the flux about 1: 2, and trace elements through wet pretreatment of glass spheres for the analysis of the major and minor components of the rock sample In addition, it is possible to improve the analysis accuracy of insoluble elements and to significantly reduce the wet pretreatment time of rock samples.

1 is a flow chart showing a trace element analysis method of rock samples according to an embodiment of the present invention.
2 to 4 are graphs showing analysis results of trace elements for three samples according to Examples and Comparative Examples.

Advantages and features of the present invention and methods for achieving them will be apparent with reference to the embodiments described below in detail with the accompanying drawings. It should be understood, however, that the invention is not limited to the disclosed embodiments, but is capable of many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, To fully disclose the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims.

Hereinafter, with reference to the accompanying drawings will be described in detail with respect to the trace element analysis method of rock samples by wet pretreatment using glass spheres according to a preferred embodiment of the present invention.

1 is a flow chart showing a trace element analysis method of rock samples according to an embodiment of the present invention.

Referring to Figure 1, the trace element analysis method of the illustrated rock sample is glass sphere formation step (S110), the first acid decomposition step (S120), the second acid decomposition step (S130), dilution step (S140) and element measurement Step S150 is included.

Glass sphere formation

In the glass sphere forming step (S110), the glass sample is mixed with the flux to form a glass sphere. At this time, the rock sample should be ground into a fine powder of less than about 100 mesh (mesh).

Although not shown in the drawings, the glass sphere forming step S110 includes an oxidation, mixing, melting, and cooling process.

In the oxidation process, the powdered rock sample is put into an electric furnace to make an oxide, and then maintained for 30 to 40 minutes while heated to 950 ~ 1000 ℃.

In the mixing process, a mixed flux of 35% lithium tetraborate (Li ₂ B ₄ O ₇ ) and 65% lithium metaborate (LiBO ₂ ) (melting point 825 ° C.) was used. Mix with.

In the melting process, the mixed rock sample is charged into a platinum crucible and then melted in an automatic fusion machine to form glass spheres. At this time, the melting temperature is preferably carried out at 1050 ℃ or less, specifically 1000 to 1050 ℃ can be presented. If the temperature exceeds 1050 ° C, volatile elements such as Pb, Cu, and Rb may be lost due to high temperature.

Meanwhile, 2.5 g of the oxidized sample and 5 g of the mixed flux were mixed in a platinum crucible (Pt95%, Au5%) and melted in an automatic melting apparatus for about 20 minutes to produce glass balls, and crushed and re-glassed glass balls to ensure homogeneity. It melt | dissolves and produces a glass sphere. The produced glass sphere is pulverized again to powder. If the weight ratio of rock sample and flux is less than 1: 2, it may cause a problem that the rock sample does not dissolve. On the contrary, if the weight ratio of rock sample and flux exceeds 1: 2, the problem of high dilution ratio is caused. Measurement problems will occur.

If, during the melting process is not perfect melting, the grinding process and the re-melting process may be further performed to ensure the homogeneity of the glass sphere to be produced.

In the grinding process, the previously prepared glass spheres are ground to an average particle size of about 100 mesh or less.

In the remelting process, the ground glass is charged into a platinum crucible and then remelted in an automatic melting apparatus. At this time, the remelting temperature may be carried out at the same temperature as the melting temperature.

In the cooling process, in order to prevent crystallization of the completely melted glass spheres in the automatic melting apparatus, a rapid cooling using a fan is performed.

Primary Acid Decomposition

In the first acid decomposition step (S120), a glass sphere is reacted with a mixed acid to make a solution. A 0.2 g glass sphere powder sample is placed in a 50 ml Teflon container and 5 ml of mixed acid having a ratio of 1: 1: 0.250 of nitric acid (HNO ₃ ), hydrofluoric acid (HF) and perchloric acid (HClO ₄ ) is added. Shake the Teflon container to mix the glass sphere and the mixed acid and then seal it may be carried out for about 24 hours at a temperature of 180 ~ 200 ℃ in the heating plate.

Here, the mixed acid is preferably a mixed acid of nitric acid (HNO ₃ ), hydrofluoric acid (HF) and perchloric acid (HClO ₄ ) in an appropriate ratio, the weight ratio of HNO ₃ , HF and HClO ₄ is 1: 1: 0.250 can be presented. After completion of the first acid decomposition process, the Teflon container is opened and the acid is evaporated from the heating plate.

Secondary acid decomposition

In the second acid decomposition step (S130), 1 ml of HClO ₄ is added to the first acid decomposed mixture, and then secondary acid decomposed. In this case, in the secondary acid decomposition step (S130), after HClO ₄ is added to the Teflon container, it may be performed at 170 ° C. for 2 to 3 hours.

This secondary acid decomposition step (S130) is carried out for the purpose of removing the fluorine compound in the mixture.

Dilution

In the dilution step (S140), the secondary acid-decomposed mixture is diluted with an aqueous HNO ₃ solution. In this case, the dilution step S140 may include a first dilution process and a second dilution process.

In the first dilution process, dilution is carried out using an aqueous 1 wt% HNO ₃ solution. At this time, the dilution ratio is approximately 32 to 35 times to prepare a first dilution solution for analyzing sub-elements (Ba, Sr, Zr) and the like by an inductively coupled plasma atomic emission spectrometer (ICP-AES).

In the second dilution process, a dilution solution for analyzing trace elements including rare earth elements is prepared by an inductively coupled plasma mass spectrometer (ICP-MS) by diluting 20 times with a 1 wt% HNO ₃ solution in the first diluted solution.

By this first and second dilution processes, the total dilution ratio is approximately 1: 1950, which is approximately 3.4, considering that the final dilution ratio is 1: 6,600 using the beaker-heating plate melting method. It can be seen that the fold is lowered.

Therefore, in this invention, the analysis accuracy of rare earth elements etc. with low density | concentration can be improved.

Elemental measurement

In the element measuring step (S150), the element contained in the diluted solution is measured. In this case, the element measuring step S150 may include a first measuring step and a second measuring step.

In the first measurement step, the first dilution solution is first measured by using an inductively coupled plasma-atomic emission spectrometer (ICP-AES). At this time, in the first measurement step, the main component element and the subcomponent element are measured together.

In the second measurement step, the second dilution solution is secondarily measured using an inductively coupled plasma-mass spectrometer (ICP-MS). In the second measurement step, trace elements and rare earth elements are measured.

In the case of the trace element analysis method using glass spheres performed in this manner, the total time required for performing the wet pretreatment is about 2 days, which is a beaker-a pretreatment method commonly used for the trace element analysis of rock samples. Considering that the total time required for the hot plate method is 4.5 to 5 days, it is about 2 times shorter.

As described so far, in the present invention, the glass sample was manufactured using a glass dilution glass bead in which the mixing ratio of the sample and the flux is 1: 2 using a glass ball wet method (automatic bead machine). After the acid decomposition process is "Example", the wet method by the beaker-heating plate method (formerly acid decomposition method) as the "comparative example", AGV-2 which is a rock standard sample of the US Geological Survey (USGS) By comparing the analysis results of three powder samples (Andesite), BHVO-2 (Basalt) and G-3 (Granite), it is possible to improve the analysis accuracy of insoluble elements and to greatly improve the wet pretreatment time of rock samples. It was confirmed that there is an effect that can be shortened.

Example

Hereinafter, the configuration and operation of the present invention through the preferred embodiment of the present invention will be described in more detail. It is to be understood, however, that the same is by way of illustration and example only and is not to be construed in a limiting sense.

Details that are not described herein will be omitted since those skilled in the art can sufficiently infer technically.

1. Trace element analysis method

Example

After preparing AGV-2 (Andesite), BHVO-2 (Basalt) and G-3 (Granite), the rock standards of the United States Geological Survey (USGS), each sample was placed in an electric furnace at 950 ° C. After heating for minutes, it was cooled in a desiccator.

Thereafter, 2.5 g of each sample was mixed with 5 g of a mixed flux in which Li ₂ B ₄ O ₇ : LiBO ₄ was mixed in a weight ratio of 35:65, introduced into an automatic melting apparatus, and then melted at 1050 ° C. for 15 minutes to carry out glass balls. Was prepared. Thereafter, the prepared glass spheres were pulverized, re-injected into an automatic melting apparatus, and re-melted at 1050 ° C. for 15 minutes to produce a homogeneous glass sphere.

Thereafter, 5 g of the glass sphere and 5 ml of the mixed acid mixed with HNO ₃ : HF: HClO ₄ in a weight ratio of 1: 1: 0.25 were reacted, and the acid was decomposed at 190 ° C. for 24 hours. Thereafter, 1 ml of HClO ₄ was further mixed into the mixture, followed by further acid decomposition and drying at 170 ° C. for 2 to 3 hours.

Thereafter, the mixture was diluted with about 7 ml of an aqueous 1% by weight HNO ₃ solution, and then analyzed for main and subcomponents using ICP-AES.

The diluted mixture was then diluted 20 times again with 1% by weight HNO ₃ solution, followed by analysis of trace elements and rare earth elements using ICP-MS.

Comparative example

The rock standards of the United States Geological Survey (USGS), AGV-2 (Andesite), BHVO-2 (Basalt), and G-3 (Granite) were prepared and acid-degraded by the beaker-heated plate method. That is, about 0.1 g of sample is placed in a 50 ml Teflon container and 5 ml of mixed acid having a ratio of hydrofluoric acid, nitric acid and perchloric acid is 1: 1: 0.25. After mixing the acid and the sample, the Teflon container is sealed, placed on a heating plate, and heated at about 200 ° C. for about one day. Open and dry the Teflon container and repeat the same process once again. Add 3 ml of aqua regia to the dried sample and heat at about 200 ° C for about a day. After drying, 1 ml of HClO ₄ and 2 ml of boric acid are added and dried on a heating plate. After drying, diluting 100 times with 10 ml of 1% by weight of HNO ₃ to prepare a first dilution solution, and analyzes the minor components by ICP-AES. Return the first dilution solution to 1% by weight HNO ₃ A second dilution solution with 20-fold dilution was made and analyzed for trace elements and rare earth elements by ICP-MS. At this time, the dilution ratio is about 1: 2000 and the total time required for pretreatment is about 4.5-5 days.

2. Trace element analysis device

Table 1 shows the analysis conditions of the Inductively Coupled Plasma-Atomic Emission Spectrometer (ICP-AES) and the Inductively Coupled Plasma-Mass Spectrometer (ICP-MS).

[Table 1]

ICP - AES

[Table 2]

ICP-MS

3. Trace element analysis result

Tables 3 to 5 show the analysis results of trace elements for the three samples according to the Examples and Comparative Examples, Figures 2 to 4 shows the trace elements of the three elements according to the Examples and Comparative Examples Each graph shows the results of the analysis.

Here, three samples were used USG rock standards AGV-2 (Andesite), BHVO-2 (Basalt), G-3 (Granite). At this time, the group 1 element is relatively positive or chalcophile element such as Cr, Co, Ni, Cu, Zn, Pb, etc., and the group 2 element is an alkali metal and alkaline earth metal group element such as Rb, Sr, Cs, Ba, etc. And indeterminate lipophilic elements such as Y, Zr, Nb, Hf, Th, and U. Group 3 elements are rare earth elements that are described separately in most cases because of their chemical similarity, and the systematic behavior of rock formation and change. 2 to 4 (a) to (c) correspond to group 1 elements to group 3 elements, and 'O' respectively shown in the graphs of FIGS. 2 to 4 (a) to (C) is an embodiment. Corresponds to Comparative Example.

[Table 3] (Unit: μg / g)

[Table 4] (Unit: μg / g)

[Table 5] (Unit: μg / g)

Referring to Tables 3 to 5 and FIGS. 2 to 4, in the case of Examples, the results of analysis of the rare earth elements corresponding to the Group 3 elements, as compared with the results of analysis of the Group 3 elements according to the comparative example performed by the acid decomposition method There was no difference and it was confirmed that the accuracy and relative standard deviation can be analyzed within the range of 15%.

In particular, in the case of the glass spheres, no loss of volatile elements such as Pb, Cu, Rb, etc. was observed. The result was obtained.

Therefore, in the case of using the rock sample trace element analysis method using the glass sphere according to the present invention, the glass sphere for the analysis of the major and minor components by wet pre-treatment used in the analysis of the trace element, to improve the analysis accuracy of insoluble elements In addition, there is an effect that can significantly reduce the pretreatment time of the rock sample.

While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not limited to the disclosed embodiments. Such changes and modifications are intended to fall within the scope of the present invention unless they depart from the scope of the present invention. Accordingly, the scope of the present invention should be determined by the following claims.

S110: glass sphere forming step
S120: first acid decomposition step
S130: secondary acid decomposition step
S140: Dilution Step
S150: Element Measurement Steps

Claims (8)

(a) mixing the rock sample with the flux to form a glass sphere;
(b) reacting the glass spheres with a mixed acid solution to primary acid decomposition;
(c) secondary acid decomposition by adding HClO ₄ to the primary acid-decomposed mixture;
(d) diluting the secondary acid decomposed mixture with an aqueous HNO ₃ solution; And
(e) measuring the elements contained in the diluted mixture;
In the step (a), the flux is characterized in that Li ₂ B ₄ O ₇ and LiBO ₂ is mixed,
The step (a)
(a-1) oxidizing the rock powder sample in an electric furnace at 950-1000 ° C. for 30-40 minutes;
(a-2) mixing the oxidized rock sample with a flux in a weight ratio of 1: 2,
(a-3) melting the mixed rock sample and flux at 1000 to 1050 ° C. to produce glass balls,
In the step (b), the mixed acid is HNO ₃ , HF and HClO ₄ The trace element analysis method of the rock sample, characterized in that mixed in a weight ratio of 1: 1: 0.250.
The method of claim 1,
After the step (a-3),
(a-4) cooling the prepared glass sphere,
(a-5) crushing the glass sphere,
(a-6) The trace element analysis method of the rock sample, characterized in that it further comprises the step of re-melting the crushed glass sphere to powder again.
delete delete The method of claim 1,
The flux
Trace element analysis method for rock samples, characterized in that 35% Li ₂ B ₄ O ₇ and 65% LiBO ₂ is mixed.
delete The method of claim 1,
The step (d)
(d-1) first diluting the mixture 32-35 times with 1% by weight aqueous HNO ₃ solution,
(D-2) The trace element analysis method of the rock sample, characterized in that it comprises the step of diluting the first diluted mixture again 20 times with 1% by weight aqueous HNO ₃ solution.
The method of claim 7, wherein
The step (e)
(e-1) measuring the first diluted mixture by an inductively coupled plasma-atomic emission spectrometer (ICP-AES);
(e-2) Trace element of the rock sample, characterized in that the secondary dilution of the mixture by using an inductively coupled plasma-mass spectrometer (ICP-MS) Analytical Method.

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