Method for detecting content of zirconium element in high-purity quartz sand

Abstract

The invention discloses a method for detecting the content of a zirconium element in high-purity quartz sand, which comprises the following steps: heating and digesting the high-purity quartz sand by using an acid digestion solution in a closed environment, and evaporating a solvent to dryness after the digestion is completed to obtain a residue; transferring the residues into a heat-resistant container by using nitric acid, evaporating the solvent to dryness, then adding strong base, and heating to carry out alkali dissolution reaction; the alkali dissolution reaction comprises the following steps: heating to 200-300 DEG C, preserving heat for a period of time, heating to 550-950 DEG C, and preserving heat for a period of time; cooling after the alkali dissolution reaction is finished, dissolving an alkali dissolution reaction product with nitric acid, and fixing the volume with pure water to obtain a sample solution; preparing a standard impurity solution and a blank sample solution; the sample solution, the standard impurity solution and the blank sample solution are tested and analyzed through ICP-OES or ICP-MS, and the content of the zirconium element in the high-purity quartz sand is obtained.

Description

Technical Field

[0001] This invention relates to the field of high-purity quartz sand detection technology, specifically to a method for detecting the zirconium content in high-purity quartz sand. Background Technology

[0002] High-purity quartz sand is a silicon dioxide material made from natural crystals, quartz minerals, or chemically synthesized. It is a key basic material and is widely used in high-tech industries such as semiconductors, optical fibers, photovoltaics, electric light sources, and bioengineering.

[0003] The purity of high-purity quartz sand has an absolute impact on its application, so precise analysis of the purity of quartz sand is often required in the industry.

[0004] The majority of zirconium in quartz sand exists as zircon (ZrSiO4), with smaller amounts existing as zircon (ZrO2) and other forms. Due to the extremely high melting points of zirconium-containing minerals (zircon: 2750℃, zircon: 2950℃), when using quartz sand as a raw material to manufacture quartz products such as quartz glass and quartz optical fibers, the zirconium-containing minerals often exist in the form of concretions, which can have a fatal impact on the quality of quartz products.

[0005] Currently, the most commonly used methods for determining the content of impurity elements in high-purity quartz sand are inductively coupled plasma optical emission spectrometry (ICP-OES) or inductively coupled plasma mass spectrometry (ICP-MS). These methods offer advantages such as the ability to simultaneously determine multiple trace elements, low detection limits, and fast analysis speed. The process involves first digesting the quartz sand to prepare a sample, followed by testing.

[0006] The main component of quartz sand is silicon dioxide. Impurity elements exist in mineral form on the surface and in the crack structure of quartz sand particles, and partially replace silicon and oxygen atoms in the crystal lattice. Therefore, to prepare the quartz sand to be tested into a sample for ICP-OES and ICP-MS testing, it is necessary to break the silicon-oxygen tetrahedral structure in the quartz sand crystal and then dissolve the impurity elements.

[0007] The most commonly used method for digesting quartz sand is the acid dissolution method. This method involves digesting the quartz sand to be tested with strong acids such as hydrofluoric acid and nitric acid, converting all the silica into silicon tetrafluoride and removing it. The residue is then dissolved in nitric acid and tested using ICP-OES or ICP-MS. For example, patent specification CN120404897A discloses a method for determining the content of impurity elements in high-purity quartz using ICP-MS, including the following steps: S1: drying the sample; S2: weighing the sample; S3: primary dissolution with strong acid I; S4: secondary dissolution with strong acid II; S5: cooling and volume adjustment; S6: testing and analyzing the standard series working solutions, sample solutions, and blank solutions on ICP-MS.

[0008] However, acid dissolution digestion of quartz sand often results in incomplete digestion and inaccurate determination of trace elements, especially the determination of zirconium (Zr) in quartz sand.

[0009] Zircon is a very stable mineral, and only a few acids, such as hydrofluoric acid, can react with it. However, the reaction between zircon and hydrofluoric acid is very slow (when zircon dissolves in acid, a zircon-rich layer forms on the surface of the zircon, which limits the digestion rate of zircon. For example, it takes more than 72 hours to digest 50 mg of zircon with 2 mL of hydrofluoric acid in a sealed container at 120°C). Therefore, it is difficult to completely digest zircon. Summary of the Invention

[0010] In view of the above-mentioned technical problems and the shortcomings of the field, the present invention provides a method for detecting the zirconium content in high-purity quartz sand. By optimizing the digestion process, the accuracy of zirconium (Zr) content measurement in quartz sand is greatly improved.

[0011] The specific technical solution is as follows: A method for determining the zirconium content in high-purity quartz sand includes: High-purity quartz sand was digested in a closed environment using an acid digestion solution and heated. After digestion, the solvent was evaporated to obtain the residue. The residue is transferred to a heat-resistant container using nitric acid, the solvent is evaporated, and then a strong alkali is added and heated to carry out an alkaline dissolution reaction. The alkaline dissolution reaction includes: first heating to 200~300℃ and holding for a period of time, then heating to 550~950℃ (e.g., 650℃, 900℃, etc., preferably 650~900℃) and holding for a period of time. After the alkaline dissolution reaction is completed and cooled, the alkaline dissolution reaction product is dissolved in nitric acid and then diluted to volume with pure water to obtain the sample solution. Prepare standard impurity solutions and blank sample solutions; The zirconium content in high-purity quartz sand was obtained by testing and analyzing the sample solution, standard impurity solution, and blank sample solution using ICP-OES or ICP-MS.

[0012] The present invention describes a method for digesting quartz sand that involves acid dissolution followed by alkali dissolution. The acid dissolution method effectively converts and removes silicon dioxide in the quartz sand, fully exposing the impurity minerals. The subsequent alkali dissolution method effectively decomposes the exposed zircon particles, thereby fully digesting the impurity minerals in the quartz sand and achieving the goal of accurately measuring the zircon content in the quartz sand.

[0013] The present invention adopts a digestion process of acid dissolution followed by alkali dissolution because if alkali dissolution is performed first and then acid dissolution is performed, the silica in the quartz sand will react with the alkali and ultrapure water to generate substances such as water glass during the process of transferring the residue in the crucible to the acid dissolution container, thus making it impossible to carry out subsequent steps.

[0014] The method of this invention can not only accurately measure the zirconium content in quartz sand, but is also applicable to the testing of the content of metallic impurity elements (such as Cr) introduced by minerals such as chromite that are difficult to dissolve by ordinary acid dissolution methods in quartz sand.

[0015] In some embodiments, the silica content in the high-purity quartz sand is above 99.998% by mass. This invention can detect trace zirconium (Zr) content in high-purity quartz sand.

[0016] The sealed environment can be achieved through an acid digestion container. The acid digestion container is made of a material that does not react with the acid digestion solution, is resistant to acid corrosion, and can withstand temperatures up to 200°C. Specifically, it may include one or more of polytetrafluoroethylene (PTEE), perfluoroalkoxyalkane (PFA), etc.

[0017] This invention employs a process where quartz sand is first placed in an acid digestion container, and after acid dissolution is complete, the acid solution is evaporated to dryness. Subsequently, the residue is transferred to a heat-resistant container such as a crucible for alkali digestion. This is because the acid digestion solution used during the acid dissolution of quartz sand corrodes the heat-resistant containers such as crucibles used for alkali digestion, and materials resistant to acid corrosion, such as polytetrafluoroethylene, cannot withstand the high temperatures during alkali digestion. The process of evaporating the acid solution to dryness is to prevent the residual acid from reacting with the alkali and impurity elements to form a complex precipitate that is insoluble in nitric acid, thus affecting the test results.

[0018] The acid digestion solution preferably includes hydrofluoric acid and nitric acid, and may also include at least one of hydrogen peroxide, hydrochloric acid, etc. Further: the mass fraction of HNO3 in the nitric acid is 65%~70%; the mass fraction of HF in the hydrofluoric acid is 40%~50%, for example 48%; the mass fraction of H2O2 in the hydrogen peroxide is 30~40%; and the mass fraction of HCl in the hydrochloric acid is 31%~38%.

[0019] More preferably, the volume ratio of nitric acid to hydrofluoric acid in the acid digestion solution is 1:1~3.

[0020] In some preferred embodiments, the amount of high-purity quartz sand used is 0.3~1 g. This is because if too little quartz sand is used, the purity test of the quartz sand may be inaccurate due to the uneven distribution of impurities; if a large amount of quartz sand is used for digestion, acid dissolution will take more than a day (a large amount of quartz sand stacked up will result in a smaller specific surface area and a higher ion concentration of the reaction products, causing the acid dissolution time to be prolonged, for example, 2 g of quartz sand requires about three days for sealed acid dissolution at 150 ℃), and it is easy to have incomplete digestion.

[0021] In some preferred embodiments, the acid digestion solution includes hydrofluoric acid, and the volume ratio of hydrofluoric acid to the mass of the high-purity quartz sand in the acid digestion solution is 8-20 mL:1 g, for example, 10 mL:1 g. Further, the hydrofluoric acid contains 40%-50% HF by mass.

[0022] In some preferred embodiments, the heating digestion temperature is 120~200℃, such as 150℃, 160℃, etc. The heating digestion of this invention is carried out in a closed environment because the boiling point of the acid used in acid dissolution is not high. Increasing the reaction temperature is beneficial to increasing the digestion rate. For example, the boiling point of hydrofluoric acid is 112.2℃, and the boiling point of nitric acid is 83℃. Open heating for acid dissolution digestion can not reach a high temperature and easily leads to acid evaporation, failing to completely digest the quartz sand. Sealed heating can increase the pressure inside the reaction vessel, allowing the reaction acid to reach a higher temperature, thereby maintaining the activity of the reaction acid and enhancing its oxidizing properties. However, if the temperature exceeds 200℃, it can easily damage the container for the acid dissolution reaction, shortening its service life.

[0023] In some preferred embodiments, the heating digestion time is 2 to 5 hours, for example, 3 hours.

[0024] In some preferred embodiments, the residue is transferred to a heat-resistant container using nitric acid with a HNO3 mass concentration of 1% to 10%.

[0025] The heat-resistant container, including crucibles, must be able to withstand high temperatures of 950°C, resist strong alkali corrosion at high temperatures, and be composed of materials whose constituent elements are not quartz sand and are not the metal elements to be tested. Specifically, it may include one or more combinations of silver, gold, platinum, nickel, graphite, etc.

[0026] The strong alkali is one that reacts with zircon (ZrSiO4) without affecting the metal elements being tested in the quartz sand, has good water solubility, and will not corrode heat-resistant containers. The purity of the strong alkali is preferably above superior grade, with a single metal impurity content of <1 ppm, and the metal impurity elements do not include zirconium.

[0027] When adding strong alkali to a heat-resistant container, it is preferable to use a clean stirring rod to gently stir, so that the strong alkali and residue are mixed evenly to avoid local clumping.

[0028] In some preferred embodiments, the mass ratio of the added strong alkali to the mass of high-purity quartz sand is (5~8):1.

[0029] In some preferred embodiments, a strong alkali is added in a dry environment to prevent the alkali from absorbing moisture and affecting weighing and subsequent volume adjustment. The dry environment can be achieved using an infrared lamp, and the ambient humidity of the dry environment is preferably less than 85%.

[0030] In some preferred embodiments, the strong base includes one or more of sodium hydroxide, potassium hydroxide, and sodium peroxide.

[0031] The strong alkali used in this invention is preferably selected in correspondence with the heat-resistant container. When sodium hydroxide or potassium hydroxide is used for alkali dissolution, it is suitable for heat-resistant containers made of materials such as silver, gold, platinum, and graphite. When sodium peroxide is used for alkali dissolution, it is suitable for heat-resistant containers made of materials such as nickel and graphite.

[0032] The alkali dissolution reaction is first preheated to 200-300℃ to remove acid-dissolved residues in the quartz sand and any moisture that may be present in the alkali, and to ensure uniform heating of the heat-resistant container. The second stage, heating to 550-950℃, is to keep the alkali in a molten state. The heating rate and holding time can be determined based on the amount of quartz sand and alkali.

[0033] In some preferred embodiments, the heating rate in the alkaline dissolution reaction does not exceed 1°C / s, for example, 0.9°C / s.

[0034] In some preferred embodiments, the alkaline dissolution reaction is carried out at 200-300°C for 10-60 min (e.g., 30 min).

[0035] In some preferred embodiments, the alkaline dissolution reaction is carried out at 550~950℃ (e.g. 650℃, 900℃, etc., preferably 650~900℃) for 10~120 min (e.g. 40 min, 60 min, etc., preferably 40~60 min).

[0036] In some preferred embodiments, the alkaline reaction product is dissolved in nitric acid with a mass concentration of 1% to 10% HNO3.

[0037] In this invention, standard impurity solutions with gradient concentrations can be prepared using standard stock solutions corresponding to each element of the analyte, with example concentrations of 0.1 ng / g, 0.2 ng / g, 0.5 ng / g, 1.0 ng / g, etc.

[0038] In this invention, the preparation method of the blank sample solution can be the same as that of the sample solution, the only difference being the absence of high-purity quartz sand.

[0039] Compared with the prior art, the beneficial effects of this invention are as follows: This invention employs a digestion and sample preparation method involving acid dissolution followed by alkali dissolution. Sufficient acid dissolution converts silica into silicon tetrafluoride, which is then removed, fully exposing zirconium-containing impurity minerals. Subsequently, alkali dissolution further digests these minerals, preparing a sample solution suitable for ICP-OES and ICP-MS testing. This method effectively dissolves zirconium-containing impurity minerals that cannot be digested by ordinary acid dissolution, allowing for accurate measurement of the zirconium content in quartz sand. Furthermore, this method is also applicable to testing the content of metallic impurity elements (such as Cr) introduced by minerals like chromite, which are difficult to digest using ordinary acid dissolution methods, in quartz sand. Detailed Implementation

[0040] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Operating methods not specifically specified in the following embodiments are generally performed under conventional conditions or as recommended by the manufacturer.

[0041] Example 1: Weigh 0.3 g of #1 quartz sand using an analytical balance and place it in a PFA dissolution vessel. Add 4 mL of digestion solution (hydrofluoric acid and nitric acid volume ratio 3:1, with HF mass fraction of 48% in hydrofluoric acid and HNO3 mass fraction of 65% in nitric acid) to the dissolution vessel. After tightening the dissolution vessel, place it on a graphite heating plate and set the heating temperature to 160 ℃ for 3 h of digestion. After the acid dissolution is complete, open the dissolution vessel, place it on a graphite heating platform, set the heating temperature to 80 ℃, and evaporate the acid solution to dryness.

[0042] Add 1 mL of 1wt% dilute nitric acid to the PFA dissolution vessel, tighten the vessel, and place it on a graphite heating plate at 80 °C for 20 min.

[0043] Pour the liquid from the PFA dissolution vessel into a silver crucible, and rinse the dissolution vessel with an appropriate amount of dilute nitric acid to fully collect the metal ions. After collection, cover the crucible with the lid.

[0044] Place the silver crucible on a graphite heating plate, evaporate the acid solution to dryness, add 1.5 g of sodium hydroxide, cover the crucible, and place it in a muffle furnace.

[0045] First, the muffle furnace is heated to 300 ℃ at a heating rate of 1 ℃ / s and held for 30 min. Then, it is heated to 900 ℃ at a rate of 0.9 ℃ / s and held for 1 h.

[0046] After the muffle furnace has cooled, remove the crucible and rinse it with 1wt% dilute nitric acid. Then, slowly transfer the solution to a beaker and add ultrapure water to the beaker to make up to the final volume to obtain the sample solution.

[0047] Prepare standard impurity solutions and blank sample solutions.

[0048] The sample solution, standard impurity solution, and blank sample solution were tested using ICP-OES.

[0049] Example 2: The only difference from Example 1 is that the quartz sand sample was changed, with #1 quartz sand replaced by #2 quartz sand; all other aspects are the same.

[0050] Example 3: The only difference from Example 1 is that the quartz sand sample was changed, and #1 quartz sand was replaced with #3 quartz sand. All other aspects are the same.

[0051] Example 4: The only difference from Example 1 is that the quartz sand sample was changed, with #1 quartz sand replaced by #4 quartz sand; all other aspects are the same.

[0052] Comparative Example 1: Weigh 0.3 g of #1 quartz sand using an analytical balance and place it in a PFA dissolution vessel. Add 4 mL of digestion solution (hydrofluoric acid and nitric acid volume ratio 3:1, with HF mass fraction of 48% in hydrofluoric acid and HNO3 mass fraction of 65% in nitric acid) to the dissolution vessel. After tightening the dissolution vessel, place it on a graphite heating plate and set the heating temperature to 160 ℃ for 3 h of digestion. After the acid dissolution is complete, open the dissolution vessel, place it on a graphite heating platform, set the heating temperature to 80 ℃, and evaporate the acid solution to dryness.

[0053] Add 1 mL of 1wt% dilute nitric acid to the PFA dissolution vessel, tighten the vessel, and place it on a graphite heating plate at 80 °C for 20 min.

[0054] After the PFA melting vessel has cooled, add ultrapure water to the beaker to make up the volume and obtain the sample solution.

[0055] Prepare standard impurity solutions and blank sample solutions.

[0056] The sample solution, standard impurity solution, and blank sample solution were tested by ICP-OES respectively. Comparative Example 2: The only difference from Comparative Example 1 is that the quartz sand sample was changed, with #1 quartz sand replaced by #2 quartz sand; all other aspects are the same.

[0057] Comparative Example 3: The only difference from Comparative Example 1 is that the quartz sand sample was changed, with #1 quartz sand replaced by #3 quartz sand; all other aspects are the same.

[0058] Comparative Example 4: The only difference from Comparative Example 1 is that the quartz sand sample was changed, with #1 quartz sand replaced by #4 quartz sand; all other aspects are the same.

[0059] Comparative Example 5: Weigh 0.3 g of #1 quartz sand using an analytical balance and place it in a PFA digestion vessel. Add 4 mL of digestion solution (hydrofluoric acid and nitric acid volume ratio 3:1, with HF mass fraction of 48% in hydrofluoric acid and HNO3 mass fraction of 65% in nitric acid) to the digestion vessel. After tightening the digestion vessel, place it in a high-pressure reactor and set the heating temperature to 180 ℃ for 24 h of digestion. After cooling, transfer the solution to a beaker and rinse several times with 1wt% dilute nitric acid to collect metal ions. Add ultrapure water to the beaker to make up to volume and shake well to obtain the sample solution.

[0060] Prepare standard impurity solutions and blank sample solutions.

[0061] The sample solution, standard impurity solution, and blank sample solution were tested using ICP-OES.

[0062] Comparative Example 6: Weigh 0.3 g of #1 quartz sand using an analytical balance and place it in a silver crucible. Add 1.5 g of sodium hydroxide, cover the crucible, and place it in a muffle furnace.

[0063] First, the muffle furnace is heated to 300 ℃ at a heating rate of 1 ℃ / s and held for 30 min. Then, it is heated to 900 ℃ at a rate of 0.9 ℃ / s and held for 1 h.

[0064] After the muffle furnace has cooled, remove the crucible and rinse it with 1wt% dilute nitric acid. Then, slowly transfer the solution to a beaker and add ultrapure water to the beaker to make up to the final volume to obtain the sample solution.

[0065] Prepare standard impurity solutions and blank sample solutions.

[0066] The sample solution, standard impurity solution, and blank sample solution were tested using ICP-OES.

[0067] Tables 1 and 2 show the experimental conditions and analytical results of the examples and comparative examples, where ppm are expressed by mass.

[0068] Table 1 Table 2 Table 1 shows the test results of different experimental methods on the impurity concentration in #1 quartz sand. It can be seen that the aluminum content measured by the methods of ordinary acid dissolution and digestion and high-pressure reactor acid dissolution and digestion is basically consistent with that measured in Example 1, but the test results of zirconium are much lower than those of Example 1. The aluminum and zirconium contents measured by ordinary alkaline dissolution and digestion are both lower than those of Example 1, indicating that the method of the present invention has a good test effect on both the common metallic element aluminum and the sparingly soluble metallic element zirconium.

[0069] Table 2 shows the test results of the impurity concentration in #2, #3, and #4 quartz sands after the present method and ordinary acid dissolution and digestion by ICP testing. It can be seen that the test results of the examples and comparative examples for aluminum content are basically consistent, while the test results of zirconium content in examples 2 and 3 are higher than those in the comparative example, indicating that the method of the present invention has a good test effect on zirconium in different types of quartz sands. #4 quartz sand basically does not contain zirconium, and the zirconium content detected in the examples and comparative examples is consistent, indicating that the method of the present invention will not lead to the additional introduction of zirconium.

[0070] In summary, this invention overcomes the shortcomings of the acid dissolution method commonly used in ICP testing, enabling the complete digestion of zirconium-related minerals in high-purity quartz sand and significantly improving the accuracy of zirconium impurity content detection in high-purity quartz sand.

[0071] Furthermore, it should be understood that after reading the above description of the present invention, those skilled in the art can make various alterations or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims.

Claims

1. A method for detecting zirconium content in high-purity quartz sand, characterized in that, include: High-purity quartz sand was digested in a closed environment using an acid digestion solution and heated. After digestion, the solvent was evaporated to obtain the residue. The residue is transferred to a heat-resistant container using nitric acid, the solvent is evaporated, and then a strong alkali is added and heated to carry out an alkaline dissolution reaction. The alkaline dissolution reaction includes: first heating to 200~300℃ and holding for a period of time, then heating to 550~950℃ and holding for a period of time. After the alkaline dissolution reaction is completed and cooled, the alkaline dissolution reaction product is dissolved in nitric acid and then diluted to volume with pure water to obtain the sample solution. Prepare standard impurity solutions and blank sample solutions; The zirconium content in high-purity quartz sand was obtained by testing and analyzing the sample solution, standard impurity solution, and blank sample solution using ICP-OES or ICP-MS.

2. The method for detecting zirconium content in high-purity quartz sand according to claim 1, characterized in that, The silica content in high-purity quartz sand is above 99.998%.

3. The method for detecting zirconium content in high-purity quartz sand according to claim 1, characterized in that, The acid digestion solution includes nitric acid and hydrofluoric acid; The volume ratio of nitric acid to hydrofluoric acid in the acid digestion solution is 1:1~3; The mass fraction of HNO3 in the nitric acid is 65%~70%; The hydrofluoric acid contains 40% to 50% HF by mass.

4. The method for detecting zirconium content in high-purity quartz sand according to claim 1, characterized in that, The dosage of high-purity quartz sand is 0.3~1 g; The acid digestion solution includes hydrofluoric acid; The volume ratio of hydrofluoric acid in the acid digestion solution to the mass ratio of the high-purity quartz sand is 8~20 mL:1 g.

5. The method for detecting zirconium content in high-purity quartz sand according to claim 1, characterized in that, The heating and digestion temperature is 120~200℃; The heating and digestion time is 2-5 hours.

6. The method for detecting zirconium content in high-purity quartz sand according to claim 1, characterized in that, The residue was transferred to a heat-resistant container using nitric acid with a mass concentration of 1% to 10% HNO3.

7. The method for detecting zirconium content in high-purity quartz sand according to claim 1, characterized in that, The mass ratio of the added strong alkali to the mass of high-purity quartz sand is (5~8):

1.

8. The method for detecting zirconium content in high-purity quartz sand according to claim 1, characterized in that, Add a strong alkali in a dry environment; The strong alkali includes one or more of sodium hydroxide, potassium hydroxide, and sodium peroxide.

9. The method for detecting zirconium content in high-purity quartz sand according to claim 1, characterized in that, In the alkaline dissolution reaction: The heating rate shall not exceed 1℃ / s; Keep warm at 200~300℃ for 10~60 minutes; Keep warm at 550~950℃ for 10~120 minutes.

10. The method for detecting zirconium content in high-purity quartz sand according to claim 1, characterized in that, The alkaline reaction product is dissolved in nitric acid with a mass concentration of 1%~10% HNO3.

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