阅读说明：本技术 一种测定含银物料中硒含量的方法 (Method for measuring selenium content in silver-containing material ) 是由 梁菊敏 田海燕 王维 蒋娟莉 李超 朱倪鑫 郭海娟 李宛豫 李睿 罗福扬 谢晓鑫 于 2021-09-10 设计创作，主要内容包括：本发明涉及一种测定含银物料中硒含量的方法,包括：将待测物料与硝酸以及硫酸混合加热至第一预设温度,得到第一混合溶液；将浓度为9-9.3mol/L的盐酸加入到所述第一混合溶液中,加热煮沸,依次加入掩蔽剂、吸附剂以及还原剂进行反应,反应后用定性滤纸过滤得到沉淀物；将所述定性滤纸和所述沉淀物加入到硝酸和盐酸中加热,得到第二混合溶液；对所述第二混合溶液进行滴定,得到硒含量。通过用特定浓度的盐酸溶液,使待测物料中的银变成氯化银沉淀,既而在此盐酸浓度下加热煮沸数分钟,使氯化银返溶,既能保证硒还原成单质,又能使银留在溶液中,过滤后与硒分离,不影响硒含量测定结果。该测试方法操作简单、快速、准确,可以应用于生产工艺过程控制分析。(The invention relates to a method for measuring selenium content in silver-containing materials, which comprises the following steps: mixing and heating a material to be detected, nitric acid and sulfuric acid to a first preset temperature to obtain a first mixed solution; adding hydrochloric acid with the concentration of 9-9.3mol/L into the first mixed solution, heating and boiling, sequentially adding a masking agent, an adsorbent and a reducing agent for reaction, and filtering by using qualitative filter paper after the reaction to obtain a precipitate; adding the qualitative filter paper and the precipitate into nitric acid and hydrochloric acid for heating to obtain a second mixed solution; and titrating the second mixed solution to obtain the selenium content. Silver in the material to be detected is changed into silver chloride precipitate by using hydrochloric acid solution with specific concentration, and the silver chloride is heated and boiled for several minutes under the hydrochloric acid concentration to re-dissolve the silver chloride, so that selenium can be reduced into a simple substance, the silver can be remained in the solution, and the silver is separated from the selenium after filtration, and the selenium content determination result is not influenced. The test method is simple, rapid and accurate to operate, and can be applied to the control and analysis of the production process.)

1. A method for determining selenium content in a silver-containing material is characterized by comprising the following steps:

mixing a silver-containing material to be detected with nitric acid and sulfuric acid, and heating to a first preset temperature to obtain a first mixed solution;

adding hydrochloric acid with the concentration of 9-9.3mol/L into the first mixed solution, heating and boiling, sequentially adding a masking agent, an adsorbent and a reducing agent for reaction, and filtering by using qualitative filter paper after the reaction to obtain a precipitate;

adding the qualitative filter paper and the precipitate into nitric acid and hydrochloric acid for heating to obtain a second mixed solution;

and titrating the second mixed solution to obtain the selenium content.

2. The method for determining the selenium content in the silver-containing material according to claim 1, wherein the step of adding hydrochloric acid with a concentration of 9-9.3mol/L into the first mixed solution, heating and boiling, sequentially adding a masking agent, an adsorbent and a reducing agent for reaction, and filtering with qualitative filter paper after the reaction to obtain a precipitate specifically comprises:

adding hydrochloric acid with the concentration of 9-9.3mol/L into the first mixed solution, heating and boiling for 3-10 minutes, adding a masking agent and an adsorbent, and heating to a second preset temperature;

adding a reducing agent into the first mixed solution with the second preset temperature in batches, and heating and boiling again;

and standing the first mixed solution after being heated and boiled again for 1-3 hours, and filtering by using qualitative filter paper to obtain a precipitate.

3. The method for determining the selenium content in the silver-containing material according to claim 1, wherein the qualitative filter paper and the precipitate are added into nitric acid and hydrochloric acid and heated to obtain a second mixed solution, wherein the volume ratio of the nitric acid to the hydrochloric acid is 3-4: 100.

4. The method of claim 1, wherein the step of heating the qualitative filter paper and the precipitate in nitric acid and hydrochloric acid to obtain a second mixed solution further comprises:

and adding urea into the second mixed solution, heating to boil, standing, and adding water to a constant volume.

5. The method for determining the selenium content in the silver-containing material according to claim 1, wherein the step of titrating the second mixed solution to obtain the selenium content specifically comprises:

adding a sodium thiosulfate standard solution and a starch solution into the second mixed solution, and titrating to an end point by using an iodine standard solution;

and calculating according to the dosage of the iodine standard solution to obtain the selenium content.

6. The method of claim 1, wherein the masking agent is tartaric acid and the adsorbent is diatomaceous earth.

7. The method of claim 1, wherein the reducing agent is sodium sulfite.

8. The method as claimed in claim 2, wherein the step of filtering the precipitate with qualitative filter paper comprises:

filtering with qualitative filter paper to obtain precipitate, washing the precipitate and a container for containing the first mixed solution with hydrochloric acid with a preset concentration respectively, and collecting washing liquid obtained by washing the container;

and filtering the washing solution by using the qualitative filter paper, and then discarding the filtrate.

9. The method of claim 8, wherein the predetermined concentration is 2-2.5 mol/L.

10. The method as claimed in claim 2, wherein the first predetermined temperature is 200-300 ℃ and the second predetermined temperature is 65-70 ℃.

Technical Field

The invention relates to the technical field of analysis and detection, in particular to a method for determining selenium content in a silver-containing material.

Background

In the control analysis of the selenium production process, various selenium detection samples comprise the following types: copper anode mud, selenium removal slag, selenium removal liquid, crude selenium, selenium-tellurium alloy, concentrate, tailings, neutralization slag, smoke dust, dynamic wave filter liquid, selenium reduction liquid and the like. For the determination of the selenium content in the industrial production process of copper anode mud, crude selenium and selenium, a volumetric method is mainly adopted for determination, and the approximate range of the silver, selenium and tellurium content is as follows when various samples of selenium are encountered in the determination process: selenium 0.3-99%, silver 0.2-60%, and tellurium about 2%.

For high-silver materials such as selenium-removed slag, silver concentrate and the like, silver and hydrochloric acid are easy to form silver chloride precipitate during selenium reduction in hydrochloric acid medium adopted by other methods, the silver chloride precipitate and selenium form precipitate which cannot be separated, and the silver reacts with iodine standard solution and thiosulfuric acid standard solution in a titration link to influence the analysis result of selenium.

For the determination method of the selenium content in the high-silver material, no standard analysis method exists in China, the existing methods such as hydroxylamine hydrochloride and hydrazine hydrate reduction need to be firstly subjected to silver removal filtering operation, the whole operation process is long, time and labor are wasted, and the requirement of rapid determination of the selenium content in the existing high-silver material cannot be met.

Therefore, the prior art is still subject to further improvement.

Disclosure of Invention

In view of the defects of the prior art, the invention aims to provide a method for measuring the selenium content in a silver-containing material, and aims to solve the problems of complicated operation flow and low detection efficiency of the conventional method for measuring the selenium content in the silver-containing material.

The technical scheme adopted by the invention for solving the technical problems is as follows:

a method of determining the selenium content of a silver-containing material, wherein the method comprises:

mixing and heating a material to be detected, nitric acid and sulfuric acid to a first preset temperature to obtain a first mixed solution;

adding hydrochloric acid with the concentration of 9-9.3mol/L into the first mixed solution, heating and boiling, sequentially adding a masking agent, an adsorbent and a reducing agent for reaction, and filtering by using qualitative filter paper after the reaction to obtain a precipitate;

adding the qualitative filter paper and the precipitate into nitric acid and hydrochloric acid for heating to obtain a second mixed solution;

and titrating the second mixed solution to obtain the selenium content.

Optionally, the method for determining the selenium content in the silver-containing material, wherein the step of adding hydrochloric acid with a concentration of 9 to 9.3mol/L into the first mixed solution, heating and boiling, sequentially adding a masking agent, an adsorbent and a reducing agent for reaction, and filtering with qualitative filter paper after the reaction to obtain a precipitate specifically includes:

adding hydrochloric acid with the concentration of 9-9.3mol/L into the first mixed solution, heating and boiling for 3-10 minutes, adding a masking agent and an adsorbent, and heating to a second preset temperature;

adding a reducing agent into the first mixed solution with the second preset temperature in batches, and heating and boiling again;

and standing the first mixed solution after being heated and boiled again for 1-3 hours, and filtering by using qualitative filter paper to obtain a precipitate.

Optionally, the method for determining the selenium content in the silver-containing material includes adding the qualitative filter paper and the precipitate into nitric acid and hydrochloric acid, and heating to obtain a second mixed solution, where a volume ratio of the nitric acid to the hydrochloric acid is 3-4: 100.

Optionally, the method for determining the selenium content in the silver-containing material, wherein after the step of adding the qualitative filter paper and the precipitate into nitric acid and hydrochloric acid for heating to obtain a second mixed solution, the method further comprises:

and adding urea into the second mixed solution, heating to boil, standing, and adding water to a constant volume.

Optionally, the method for determining the selenium content in the silver-containing material, wherein the step of titrating the second mixed solution to obtain the selenium content specifically includes:

adding a sodium thiosulfate standard solution and a starch solution into the second mixed solution, and titrating to an end point by using an iodine standard solution;

and calculating according to the dosage of the iodine standard solution to obtain the selenium content.

Optionally, the method for determining the selenium content in the silver-containing material comprises the steps of using tartaric acid as the masking agent and using diatomite as the adsorbent.

Optionally, the method for determining selenium content in silver-containing material is described, wherein the reducing agent is sodium sulfite.

Optionally, the method for determining the selenium content in the silver-containing material, wherein the filtering with qualitative filter paper to obtain the precipitate specifically includes:

filtering with qualitative filter paper to obtain precipitate, washing the precipitate and a container for containing the first mixed solution with hydrochloric acid with a preset concentration respectively, and collecting washing liquid obtained by washing the container;

and filtering the washing solution by using the qualitative filter paper, and then discarding the filtrate.

Optionally, the method for determining the selenium content in the silver-containing material is used, wherein the predetermined concentration is 2-2.5 mol/L.

Optionally, the method for determining the selenium content in the silver-containing material includes that the first preset temperature is 200-.

Has the advantages that: according to the method for determining the selenium content in the silver-containing material, the hydrochloric acid solution with specific concentration (9-9.3mol/L) is used, so that the silver in the material to be determined is changed into silver chloride precipitate, the silver chloride is heated and boiled for several minutes under the hydrochloric acid concentration, the silver chloride is re-dissolved, the selenium is reduced into a simple substance, the silver is remained in the solution, and the silver is separated from the selenium after filtration, so that the selenium content determination result is not influenced. The test method is simple, rapid and accurate to operate, and can be applied to the control and analysis of the production process.

Drawings

Fig. 1 is a schematic flow chart of a method for determining selenium content in a silver-containing material according to an embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention clearer and clearer, the present invention is further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. As used herein, the singular forms "a", "an", "the" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. As used herein, the term "and/or" includes all or any element and all combinations of one or more of the associated listed items.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

As shown in fig. 1, the invention discloses a method for determining selenium content in a silver-containing material, which comprises the following steps:

s10, mixing the material to be detected, nitric acid and sulfuric acid, and heating to a first preset temperature to obtain a first mixed solution.

Specifically, the material to be detected can be the de-selenium slag and the silver concentrate with higher silver content, and the used nitric acid and sulfuric acid are analytically pure. Wherein, the proportion of the nitric acid and the sulfuric acid can be added according to the volume ratio of 5: 2.

For example, 0.1g of the material to be measured may be weighed into a beaker, and 10ml of nitric acid and 4ml of sulfuric acid may be added to the beaker. The first preset temperature can be more than 200 ℃. The beaker is covered by a surface dish in the heating process. The heating device used for heating may be electric heating or alcohol lamp heating.

S20, adding hydrochloric acid with the concentration of 9-9.3mol/L into the first mixed solution, heating and boiling, sequentially adding a masking agent, an adsorbent and a reducing agent for reaction, and filtering with qualitative filter paper after the reaction to obtain a precipitate.

Specifically, the amount of hydrochloric acid with a concentration of 9-9.3mol/L can be adjusted according to the amount of the sample detected in the experiment, for example, 0.1g of the sample is weighed in the step S10, at this time, 9mol/L hydrochloric acid can be removed, the surface dish and the wall of the beaker are cleaned until the liquid in the beaker reaches 50ml, and then the solution is heated and boiled to dissolve the silver chloride precipitate again. The masking agent can mask tartaric acid and other impurities in the solution, so that the interference of the impurities on the experimental result is avoided. The adsorbent is diatomite, and selenium is attached to the adsorbent by utilizing the adsorbability of the diatomite. The reducing agent may be sodium sulfite to reduce selenium from the solvent. Wherein, the reaction is carried out at a certain temperature, after the tartaric acid, the kieselguhr and the sodium sulfite are added, the reaction vessel is covered on the reaction vessel and heated to boil, and the reaction vessel is placed for 1.5 hours to ensure that the reaction is complete. It should be noted that the heating and boiling refers to boiling of the reaction solution by heating under a normal atmospheric pressure.

When the reaction is complete, the product after the reaction can be filtered by using quick qualitative filter paper to obtain a precipitate.

Specifically, a precipitate is obtained by filtration with qualitative filter paper, the precipitate and a container for containing the first mixed solution are respectively washed with hydrochloric acid with a predetermined concentration, and a washing solution obtained by washing the container is collected; and filtering the washing solution by using the qualitative filter paper, and then discarding the filtrate. In the present embodiment, the hydrochloric acid of the predetermined concentration refers to hydrochloric acid of a concentration of 2 to 2.5 mol/L.

And S30, adding the qualitative filter paper and the precipitate into nitric acid and hydrochloric acid, and heating to obtain a second mixed solution.

Specifically, qualitative filter paper may be placed in a beaker together with the precipitate, nitric acid and hydrochloric acid may be added, and then heated to dissolve the filter paper, resulting in a second mixed solution. Wherein the volume ratio of the nitric acid to the hydrochloric acid is 3-4:100, such as 4: 100.

And S40, titrating the second mixed solution to obtain the selenium content.

Specifically, urea is added into the second mixed solution, a watch glass and the wall of a beaker are washed with water, then the mixed solution is heated and boiled, the watch glass is taken off, the watch glass and the wall of the beaker are washed with water again, and after the mixed solution is cooled to room temperature, water is added to the mixed solution to fix the volume. An excess of sodium thiosulfate standard solution, starch solution, was added and titrated with iodine standard solution until blue color appeared. And then calculating to obtain the content of the selenium.

In the present embodiment, the basic principle is as follows:

in a 70-75% hydrochloric acid medium and in the presence of tartaric acid, selenium is reduced to elemental form with anhydrous sodium sulfite and separated from other impurities, and when elemental selenium is converted to selenic acid, it can react with excess sodium thiosulfate in dilute hydrochloric acid, the excess sodium thiosulfate is titrated with an iodine standard solution using starch as an indicator. The reaction is as follows:

H₂SeO₃+4Na₂S₂O₃+4HCl→Na₂SeS₄O₆+Na₂S₄O₆+4NaCl+3H₂O

2Na₂S₂O₃+I₂→Na₂S₂O₃+2NaI

the method for determining the selenium content in a silver-containing material provided by the present invention is further explained by the following specific examples. It should be noted that, the (1+4), (1+3), and (3+1) hydrochloric acid used in the following examples are parts by volume, such as (1+4) hydrochloric acid, 4 volumes of water, and 1 volume of hydrochloric acid.

Example 1

The detection sample used is a high-silver material such as silver concentrate (silver content is 30-60%), and the detection method adopted in the embodiment is a detection method commonly used in the prior art, and comprises the following specific detection steps:

1. a sample of 0.1000 g was weighed into a 250ml beaker.

2. Adding 10ml of nitric acid and 4ml of sulfuric acid, heating to slight smoke, taking down and cooling.

3. The watch glass and the wall of the glass are flushed with (1+4) hydrochloric acid, heated until silver chloride is condensed, cooled slightly, filtered by quick qualitative filter paper, the beaker is washed with (1+4) hydrochloric acid, precipitated for 5-6 times, the precipitate is discarded, and the filtrate is collected in a 250ml beaker.

4. Adding 1-2 g of tartaric acid, and adjusting the hydrochloric acid acidity of the system to 70-75%. Adding 0.5g of diatomite, heating to near boiling, adding a small amount of anhydrous sodium sulfite for many times to completely precipitate selenium, then adding 0.2 g of anhydrous sodium sulfite, covering a watch glass, boiling for 1min, and standing for 1.5 h.

5. Filter with quick qualitative filter paper, wash the precipitate with (1+4) hydrochloric acid, beaker 5-7 times, and discard the filtrate.

6. The filter paper and the precipitate are placed in an original beaker, 6-8 drops of nitric acid and 10ml of hydrochloric acid are added, and the filter paper is dissolved by heating.

7. Adding 3g of urea, flushing the watch glass and the cup wall with water, heating and boiling, taking off the flushed watch glass and the cup wall, cooling to room temperature, and adding water to about 150 ml.

8. An excess of sodium thiosulfate standard solution, 5ml (5g/L) starch, was added and titrated with iodine standard solution until blue color appeared as an endpoint.

Example 2

The detection sample used is a high-silver material such as silver concentrate (silver content is 30-60%), and the detection method adopted in the embodiment is the detection method provided by the invention, and the detection steps are as follows:

1. a sample of 0.1g (to the nearest 0.0001g) was weighed into a 250ml beaker.

2. 10ml of nitric acid and 4ml of sulfuric acid are added, heated to slight smoke, removed and cooled.

3. The watch glass and the cup wall are flushed by (3+1) hydrochloric acid to 50ml, heated and boiled for a plurality of minutes, 1g of tartaric acid and 0.5g of diatomite are added and heated to near boiling, anhydrous sodium sulfite is added for a plurality of times to completely precipitate selenium, the watch glass is covered and boiled for 1 minute, and the watch glass is placed for 1.5 hours.

4. Filtering by using quick qualitative filter paper, washing a beaker by using (1+4) hydrochloric acid, precipitating for 5-7 times, and discarding filtrate.

5. Putting the filter paper and the precipitate into an original beaker, adding 6-8 drops of nitric acid (analytically pure) and 10ml of hydrochloric acid (analytically pure), and heating to dissolve the filter paper.

6. Adding 3g urea, washing the watch glass and the cup wall with water, heating and boiling, taking off the washed watch glass and the cup wall, cooling to room temperature, and adding water to 150 ml.

7. An excess of sodium thiosulfate standard solution, 5ml (5g/L) of starch, was added and titrated with iodine standard solution until blue color appeared as an end point.

Compared with the method adopted in the prior art, the detection method provided by the invention omits a step of filtering and desilvering.

Further, the feasibility analysis of removing one filtration was as follows:

because the silver ions are precipitated by (1+4) HCl (the optimal acidity of the precipitated silver ions is (1+4) HCl medium) to remove the interference of the silver ions on the selenium. So the first filtration is performed and the precipitated selenium is performed in (3+1) HCl medium (the optimal acidity condition for precipitated selenium is (3+1) HCl medium), so HCl is added to the filtrate to increase the acidity from (1+4) HCl to (3+1) HCl medium. Resulting in a solution volume of 150-200 ml. What would be the case if boiling with (3+1) HCl were not used, but (1+4) HCl?

According to experimental determination, the content of silver ions in a sample solution before and after (1+4) HCl boiling and filtering is removed by (1+4) HCl boiling and filtering, and the removal rate is more than 98%. And after (3+1) HCl is boiled and filtered, about 96 percent of silver ions exist in the solution, and a large amount of silver ions existing in the solution in the selenium filtering link are discarded along with the filtrate.

Is a large amount of Ag ions present in the filtrate after boiling with (3+1) HCl medium that would interfere with the precipitation (reduction) of selenium ions? Is a small amount of silver in the form of silver chloride entering the titration link with selenium through the selenium filtration link affect the final analysis result?

A comparison test is carried out aiming at the problems, so that the first filtration is omitted, whether a large amount of silver ions interfere with precipitated selenium ions or not and whether a small amount of silver chloride precipitates interfere with analysis results or not are omitted, the analysis results of different high-silver materials are compared by different analysts, and the comparison results are as follows:

the selenium content is less than or equal to 2.00 percent, and the allowance is 0.20 percent; the selenium content is more than 2.00 percent, and the allowance is 0.25 percent; the comparative analysis of the original method and the optimized method was performed on 20 samples by 4 analysts, and the individual maximum analysis error of the samples was only one sample exceeding the tolerance.

The following conclusions are drawn through experimental comparison:

1. a small amount of silver chloride precipitate generated by changing the concentration of the hydrochloric acid does not influence the analysis result;

2. the difference between the analysis result after the first filtering step and the original analysis result is within the tolerance range.

Further, in order to ensure the accuracy, i.e., the feasibility, of the analytical method, the samples were recovered in the presence of standards, and the recovery rates were 99.93%, 99.83%, and 99.83%, respectively, for the three times.

It is to be understood that the invention is not limited to the examples described above, but that modifications and variations may be effected thereto by those of ordinary skill in the art in light of the foregoing description, and that all such modifications and variations are intended to be within the scope of the invention as defined by the appended claims.