阅读说明：本技术 一种高镍基体溶液中铬的分析方法 (Analysis method of chromium in high-nickel matrix solution ) 是由 李婷 李希凯 赵有刚 梁玉霞 赵志虎 赵一华 于 2021-07-02 设计创作，主要内容包括：本发明属于高镍基体溶液检测技术领域,公开了一种高镍基体溶液中铬分析方法,以解决现有技术硫酸镍等镍基体溶液中的铬元素分析中存在的技术问题,本发明通过配置溶液、绘制工作曲线、配置待测镍溶液、计算出待测镍溶液中铬含量等步骤,本发明中溶液中的氢氧化铁只与三价铬形成共沉淀,在pH=10的氨水与氯化铵缓冲溶液中,三价铬与氢氧化铁形成共沉淀与镍分离的方法取得了满意效果,本发明消除了高镍基体对微量铬测定的干扰,能够快速、准确地检测镍电解新液、电积新液、混合阳极液等镍基体溶液中的铬含量,以达到严格控制电镍中杂质元素铬的含量的,保证电镍产品品级率的目的。(The invention belongs to the technical field of high nickel matrix solution detection, and discloses a method for analyzing chromium in a high nickel matrix solution, in order to solve the technical problems in the analysis of chromium elements in nickel-based bulk solutions such as nickel sulfate and the like in the prior art, the method comprises the steps of preparing the solution, drawing a working curve, preparing a nickel solution to be detected, calculating the chromium content in the nickel solution to be detected and the like, wherein ferric hydroxide in the solution only forms coprecipitation with trivalent chromium, the method for forming coprecipitation of trivalent chromium and ferric hydroxide and separating nickel in the ammonia water and ammonium chloride buffer solution with pH =10 obtains satisfactory effect, eliminates the interference of a high-nickel matrix on the determination of trace chromium, can quickly and accurately detect the chromium content in nickel matrix solutions such as nickel electrolysis new solution, electrodeposition new solution, mixed anolyte and the like, the method can strictly control the content of impurity element chromium in the nickel and ensure the grade rate of the nickel product.)

1. The method for analyzing chromium in the high nickel matrix solution is characterized by comprising the following steps of:

step one, preparing a 2mg/mL ferrous ion solution, an ammonia buffer solution with the pH value of 10, a 1mg/mL trivalent chromium standard storage solution, a 2mg/mL trivalent chromium standard solution, a 1g/L nickel substrate solution and an 80g/L sodium sulfate solution;

step two, transferring 0.00mL, 2.50mL, 5.00mL, 7.50mL, 10.00mL and 15.00mL of the prepared trivalent chromium standard solution in the step one into five 100mL volumetric flasks respectively, then adding 5mL of 80g/L sodium sulfate solution and 20mL of 1.19g/mL concentrated hydrochloric acid into each volumetric flask, and fixing the volume by water to ensure that the chromium concentration in the solution in the volumetric flasks is 0.00 mg/L, 0.25mg/L, 0.50mg/L, 0.75mg/L and 1.00mg/L in sequence;

step three, using air-acetylene flame, adjusting the water to zero at the 357.9nm wavelength of an atomic absorption spectrometer, measuring the absorbance of the standard solution in the step two by using a flame atomic absorption spectrometry, and drawing a working curve by taking the concentration as an abscissa and the absorbance as an ordinate;

putting 50mL of 1g/L nickel substrate solution into a 500mL triangular beaker, adding 0.5mL-2 mL of 2mg/mL ferrous ion solution, adding 50mL of ammonia buffer solution with the pH value of 10, and stirring for 2-3 min;

step five, transferring the coprecipitate in the four-triangle beaker into a glass sand funnel, washing with ammonia water (1 + 10), adding 5mL of 20% hydrochloric acid into the glass sand funnel, performing suction filtration in a 20mL colorimetric tube after the precipitate is dissolved, washing the glass sand funnel with 20% hydrochloric acid for three times, combining the washing solutions into the 20mL colorimetric tube, adding 1mL of a masking agent into the colorimetric tube, performing constant volume to 20mL of scales with 20% hydrochloric acid, and uniformly mixing to form a nickel solution to be detected;

and step six, using air-acetylene flame to the nickel solution to be detected in the step five, adjusting the water to zero at the 357.9nm wavelength of an atomic absorption spectrometer, measuring the absorbance of chromium in the test solution, and automatically calculating the chromium content in the nickel solution to be detected according to the working curve drawn in the step three.

2. The method for analyzing chromium in a high nickel matrix solution as claimed in claim 1, wherein: the acetylene flow in the third step and the sixth step is 2000 mL/min-2800L/min.

3. The method for analyzing chromium in a high nickel matrix solution as claimed in claim 3, wherein: the acetylene flow is preferably 2500 mL/min.

4. The method for analyzing chromium in a high nickel matrix solution as claimed in claim 1, wherein: in the third step and the sixth step, the height of the burner is 14mm-16mm, the position of the burner is-1 mm, and the flow rate of the burner is 2.5L/min.

5. The method for analyzing chromium in a high nickel matrix solution as set forth in claim 1, wherein: and in the fourth step, washing with ammonia water, quantitatively transferring, carrying out vacuum filtration until the mixture is dry, continuously washing the wall of the glass sand funnel and the coprecipitate with ammonia water for three times, washing the wall of the glass sand funnel with distilled water, and carrying out vacuum filtration for three times until the coprecipitate is dry.

6. The method for analyzing chromium in a high nickel matrix solution as set forth in claim 1, wherein: preferably, 1mL of a 2mg/mL ferrous ion solution is added in step four.

7. The method for analyzing chromium in a high nickel matrix solution as set forth in claim 4, wherein: and the masking agent in the step five is a sodium sulfate solution with the concentration of 3.0g/L-5.0 g/L.

8. The method for analyzing chromium in a high nickel matrix solution as set forth in claim 7, wherein: the masking agent is preferably a 4.0g/L sodium sulfate solution.

9. The method for analyzing chromium in a high nickel matrix solution as set forth in claim 1, wherein: and carrying out a reagent blank experiment along with the step four and the step five.

Technical Field

The invention relates to the technical field of high nickel matrix solution detection, in particular to a method for analyzing chromium in a high nickel matrix solution.

Background

In the production process of soluble anode electrolysis and insoluble anode electrodeposition of nickel sulfide, the produced nickel sulfate solution mainly contains about 80g/L of nickel, and also contains impurity elements such as iron, chromium and the like. In a large-scale nickel hydrometallurgy production flow, both an intermediate flow and upstream and downstream customers have urgent requirements on analysis of chromium elements in nickel matrix solutions such as nickel sulfate and the like, a nickel matrix seriously interferes with chromium determination, no method is available at present for effectively and accurately detecting the chromium content in the nickel matrix solution, and the prior art cannot solve the technical problems.

Disclosure of Invention

The invention aims to solve the technical problem in the analysis of chromium elements in nickel base body solutions such as nickel sulfate and the like in the prior art, and provides a method for analyzing chromium in a high-nickel base body solution.

In order to achieve the purpose, the invention adopts the following technical scheme:

a method for analyzing chromium in a high nickel matrix solution comprises the following steps:

step one, preparing a 2mg/mL ferrous ion solution, an ammonia buffer solution with the pH value of 10, a 1mg/mL trivalent chromium standard storage solution, a 2mg/mL trivalent chromium standard solution, a 1g/L nickel substrate solution and an 80g/L sodium sulfate solution;

step two, transferring 0.00mL, 2.50mL, 5.00mL, 7.50mL, 10.00mL and 15.00mL of the prepared trivalent chromium standard solution in the step one into five 100mL volumetric flasks respectively, then adding 5mL of 80g/L sodium sulfate solution and 20mL of 1.19g/mL concentrated hydrochloric acid into each volumetric flask, and fixing the volume by water to ensure that the chromium concentration in the solution in the volumetric flasks is 0.00 mg/L, 0.25mg/L, 0.50mg/L, 0.75mg/L and 1.00mg/L in sequence;

step three, using air-acetylene flame, adjusting the water to zero at the 357.9nm wavelength of an atomic absorption spectrometer, measuring the absorbance of the standard solution in the step two by using a flame atomic absorption spectrometry, and drawing a working curve by taking the concentration as an abscissa and the absorbance as an ordinate;

putting 50mL of 1g/L nickel substrate solution into a 500mL triangular beaker, adding 0.5mL-2 mL of 2mg/mL ferrous ion solution, adding 50mL of ammonia buffer solution with the pH value of 10, and stirring for 2-3 min;

step five, transferring the coprecipitate in the four-triangle beaker into a glass sand funnel, washing with ammonia water (1 + 10), adding 5mL of 20% hydrochloric acid into the glass sand funnel, performing suction filtration in a 20mL colorimetric tube after the precipitate is dissolved, washing the glass sand funnel with 20% hydrochloric acid for three times, combining the washing solutions into the 20mL colorimetric tube, adding 1mL of a masking agent into the colorimetric tube, performing constant volume to 20mL of scales with 20% hydrochloric acid, and uniformly mixing to form a nickel solution to be detected;

and step six, using air-acetylene flame to the nickel solution to be detected in the step five, adjusting the water to zero at the 357.9nm wavelength of an atomic absorption spectrometer, measuring the absorbance of chromium in the test solution, and automatically calculating the chromium content in the nickel solution to be detected according to the working curve drawn in the step three.

Furthermore, the flow rate of acetylene in the third step and the sixth step is 2000 mL/min-2800L/min.

Further, the acetylene flow rate is preferably 2500 mL/min.

Further, the height of the burner in the third step and the sixth step is 14mm-16mm, the position of the burner is-1 mm, and the flow rate of the burner is 2.5L/min.

And further, washing with ammonia water in the fourth step, quantitatively transferring, carrying out vacuum filtration until the mixture is dry, continuously washing the wall of the glass sand funnel and the coprecipitate with ammonia water for three times, washing the wall of the glass sand funnel with distilled water, and carrying out vacuum filtration on the coprecipitate for three times until the wall is dry.

Further, 1mL of a 2mg/mL ferrous ion solution is preferably added in the fourth step.

Further, in the fifth step, the masking agent is a sodium sulfate solution with the concentration of 3.0g/L-5.0 g/L.

Further, the masking agent is preferably a 4.0g/L sodium sulfate solution.

And further, carrying out a reagent blank experiment along with the step four and the step five.

Compared with the prior art, the invention has the following beneficial effects:

according to the invention, because the concentration of nickel in the nickel matrix solution reaches 80g/L and the content of chromium element is only about 0.01mg/L, when the effective detection of the element to be detected is ensured, the interference of nickel on chromium cannot be eliminated by direct measurement, and therefore, the chromium and the nickel need to be separated and then measured. In the present invention, the ferric hydroxide in the solution is only in the form of trivalent chromiumThe method for forming coprecipitation of trivalent chromium and ferric hydroxide and separating nickel in ammonia water and ammonium chloride buffer solution with pH =10 has satisfied effect. Using ferrous iron (Fe)²⁺) Reducing hexavalent chromium (Cr) in solution⁶⁺) Is trivalent chromium (Cr)³⁺) Generated ferric ion (Fe)³⁺) And can also be used as a coprecipitator to enrich trivalent chromium (Cr) in solution³⁺) Thereby realizing the determination of the total chromium in the nickel matrix solution. The interference of a high-nickel matrix on the determination of trace chromium is eliminated, and the chromium content in nickel matrix solutions such as new nickel electrolysis solution, new electrodeposition solution, mixed anolyte and the like can be rapidly and accurately detected, so that the aims of strictly controlling the content of impurity element chromium in the electrolytic nickel and ensuring the grade rate of the electrolytic nickel product are fulfilled.

Drawings

FIG. 1 is a graph showing the effect of acetylene flow on absorbance;

FIG. 2 is a graph of the effect of burner height on chromium absorbance;

FIG. 3 is a graph of the effect of burner position on absorbance;

FIG. 4 is a graph showing the experimental amount of precipitant;

FIG. 5 is a graph showing the ammonia buffer solution dosage test;

FIG. 6 is a graph of a stirring time selection experiment;

FIG. 7 is a graph showing the experiment of hydrochloric acid concentration.

Detailed Description

The invention is further illustrated by the following examples.

Example (b):

preparation of reagents

1. Preparation of ferrous ion solution: weighing 1.000g of iron powder with the mass fraction of more than 99.90 percent, placing the iron powder in a 500mL beaker, adding 20mL of hydrochloric acid with the density of 1.19g/mL, covering a watch glass, heating and dissolving the iron powder to a small volume at low temperature, taking down the beaker, cooling, washing the watch glass and the wall of the beaker with water, transferring the beaker into a 500mL volumetric flask, and fixing the volume with water, wherein the solution lmL contains 2mg of ferrous ions;

2. pH =10 preparation of ammonia buffer solution: weighing 140g of ammonium chloride, dissolving in water, adding 1200mL of ammonia water with the density of 0.90g/mL, and diluting with water to 2000mL to obtain an ammonia buffer solution with the pH = 10;

3. preparation of trivalent chromium standard storage solution: weighing 1.000g of chromium powder with the mass fraction of more than 99.95 percent, placing the chromium powder in a 400mL beaker, adding 20mL of hydrochloric acid with the density of 1.19g/mL, covering a watch glass, heating to dissolve, cooling to room temperature, transferring to a 1000mL volumetric flask, diluting with water to the scale, and uniformly mixing. 1mL of this solution contained 1mg of trivalent chromium;

4. preparation of trivalent chromium standard solution: transferring 2.00mL of trivalent chromium standard storage solution into a 200mL volumetric flask, adding 5mL of hydrochloric acid with the density of 1.19g/mL, diluting with water to a scale, and uniformly mixing to obtain a trivalent chromium standard solution, wherein 1mL of the trivalent chromium standard storage solution contains 10 microgram of chromium (III);

5. preparing a nickel matrix solution: weighing 1.0000 g of metal nickel with the mass fraction of more than 99.95 percent, placing the metal nickel in a 500mL beaker, adding 20mL of nitric acid, covering a watch glass, heating to dissolve and evaporate the metal nickel to a small volume, taking down and cooling the metal nickel, washing the watch glass and the cup wall with water, heating to dissolve salts, cooling the metal nickel, transferring the cooled metal nickel into a 1000mL volumetric flask, and fixing the volume with water to obtain a nickel matrix solution, wherein lmL contains lmg of nickel;

6. preparation of 80g/L sodium sulfate solution: weighing 80g of sodium sulfate, placing the sodium sulfate in a 500mL beaker, dissolving the sodium sulfate in water, adding water to a constant volume of 1000mL, and uniformly mixing to obtain 80g/L of sodium sulfate solution.

A method for analyzing chromium in a high nickel matrix solution comprises the following steps:

step one, preparing a 2mg/mL ferrous ion solution, an ammonia buffer solution with the pH value of 10, a 1mg/mL trivalent chromium standard storage solution, a 2mg/mL trivalent chromium standard solution, a 1g/L nickel substrate solution and an 80g/L sodium sulfate solution.

And step two, transferring 0.00mL, 2.50mL, 5.00mL, 7.50mL, 10.00mL and 15.00mL of the prepared trivalent chromium standard solution in the step one into five 100mL volumetric flasks, adding 5mL of 80g/L sodium sulfate solution and 20mL of 1.19g/mL concentrated hydrochloric acid into each volumetric flask, and fixing the volume by using water to ensure that the chromium concentration in the solution in the volumetric flasks is 0.00 mg/L, 0.25mg/L, 0.50mg/L, 0.75mg/L and 1.00mg/L in sequence.

And step three, using air-acetylene flame, adjusting the water to zero at the 357.9nm wavelength of the atomic absorption spectrometer, measuring the absorbance of the standard solution in the step two by using a flame atomic absorption spectrometry, and drawing a working curve by taking the concentration as an abscissa and the absorbance as an ordinate.

And step four, putting 50mL of 1g/L nickel substrate solution into a 500mL triangular beaker, adding 0.5mL-2 mL of 2mg/mL ferrous ion solution, adding 50mL of ammonia buffer solution with the pH value of 10, and stirring for 2-3 min.

And step five, transferring the coprecipitate in the triangular beaker into a glass sand funnel, washing the coprecipitate with ammonia water (1 + 10), quantitatively transferring the coprecipitate, carrying out vacuum filtration until the coprecipitate is dry, continuously washing the wall of the glass sand funnel and the coprecipitate with the ammonia water for three times, washing the wall of the glass sand funnel with distilled water, and carrying out vacuum filtration for three times until the coprecipitate is dry. Adding 5mL of 20% hydrochloric acid into a glass sand funnel, after dissolving the precipitate, performing suction filtration in a 20mL colorimetric tube, washing the glass sand funnel three times by using the 20% hydrochloric acid, combining the washing solutions in the 20mL colorimetric tube, then adding 1mL of 3.0-5.0 g/L sodium sulfate solution serving as a masking agent into the colorimetric tube, then fixing the volume to 20mL scale by using the 20% hydrochloric acid, and uniformly mixing to form the nickel solution to be detected.

And step six, using air-acetylene flame to the nickel solution to be detected in the step five, wherein the acetylene flow is 2000mL/min-2800L/min, the burner height is 14mm-16mm, the burner position is-1 mm, and the burner flow is 2.5L/min. And (3) adjusting the wavelength of 357.9nm of the atomic absorption spectrometer to zero by using water, measuring the absorbance of chromium in the test solution, and calculating the chromium content according to the working curve.

The chromium content is expressed in terms of mass concentration, and the value is expressed in terms of g/L and is calculated according to the following formula:

in the formula: rho-the concentration of chromium in the test solution, mg/L, is obtained by checking on a working curve;

ρ₀-concentration of chromium in reagent blank solution, mg/L;

v is the volume of test solution, mL; (20 mL)

V₀And transferring the amount of the nickel matrix solution in mL. (50 mL)

In the invention, the raw materials of the reagents are analytically pure reagents, and the used water is distilled water or deionized water or water with equivalent purity.

Selection of acetylene gas flow

The chromium absorbance was measured by changing the flow rate of acetylene gas using a 0.50mg/L chromium standard solution while fixing the other instrument conditions, and the results are shown in FIG. 1.

The experimental results in fig. 1 show that the absorbance of chromium gradually increases with the increase of acetylene flow, and in order to ensure the measurement stability, the acetylene flow is selected to be 2500 mL/min.

Selection of burner height

The chromium absorbance was measured by using a 0.50mg/L standard solution of chromium and adjusting the heights of different burners while keeping the conditions of other instruments constant, and the results are shown in FIG. 2.

The experimental result of figure 2 shows that the measurement sensitivity is highest when the height of the burner is 14mm-16mm, and the height of the burner is 15mm in the patent.

Selection of burner position

The chromium absorbance measured at different burner positions was adjusted using a 0.50mg/L chromium standard solution, with the other instrument conditions fixed, and the results are shown in FIG. 3.

The data in FIG. 3 shows that the chromium absorbance is highest at the burner position of-1 mm. In this embodiment the burner position is chosen to be-1 mm.

Selection of the amount of ferrous ions

Adding different amounts of Fe²⁺The solution is added into seven 50mL samples of the new nickel electrolysis solution, 1mg/mL of trivalent chromium standard storage solution is added into 1.00mL in sequence, and the chromium concentration in the solution is measured, and the result is shown in figure 4.

As can be seen from FIG. 4, when Fe²⁺ When the addition amount of the solution is 1.0mL, the concentration of chromium in a sample to be detected is the highest, and the generated coprecipitation is more complete, so that proper Fe is obtained²⁺The amount added was 1.0 mL.

Selection of the amount of the ammoniacal buffer solution

Two experimental samples with different chromium contents were selected, different amounts of ammoniacal buffer solutions were added, and the absorbance of chromium was measured according to the experimental method, as shown in fig. 5.

As can be seen from FIG. 5, the assay results stabilized with increasing amounts of ammonia buffer, which is selected herein to be 50 mL.

Selection of the stirring time

Samples were treated with different selected stirring times according to the experimental method, and the experimental results are shown in fig. 6.

The stirring time has important influence on the completion of the coprecipitation, and the analysis speed is improved as much as possible on the premise of ensuring the completion of the precipitation, so that the stirring time is selected to be 2-3 min.

Selection of dissolution and acidity thereof

Compared with two solutions of nitric acid and hydrochloric acid, the speed of dissolving the coprecipitation by using the hydrochloric acid as the solution is obviously superior to that of the nitric acid through experiments, so that the hydrochloric acid is used as the solution. The concentration of the solution hydrochloric acid was chosen experimentally, see fig. 7.

Nickel interference test

Sample addition of Fe²⁺After coprecipitation, separation and enrichment, the nickel content in the solution to be detected is about 30mg/L-80 mg/L. Different amounts of nickel were added to the 0.25mg/L and 1.00mg/L chromium standard solutions, respectively, and the interference of nickel with chromium element was examined, as shown in Table 1.

TABLE 1 Nickel interference test

As can be seen from Table 1, nickel negatively interferes with the determination of chromium.

Iron interference experiment

The iron content in the solution to be tested is about 100mg/L, different amounts of iron are added into the chromium standard solution of 0.25mg/L and 1.00mg/L respectively, and the absorbance of the chromium element is measured according to an experimental method, and the result is shown in Table 2.

TABLE 2 iron interference experiment

As can be seen from the data in table 2, iron negatively interferes with the determination of chromium.

As can be seen from interference experiment examination, the measurement of chromium elements by nickel and iron is interfered, so that a proper masking agent needs to be selected to eliminate the interference of nickel and iron on chromium.

Influence of addition amount of sodium sulfate as masking agent on nickel element

Different sodium sulfate solutions were added to the chromium standard solutions of 0.25mg/L and 1.00mg/L, respectively, each containing 80mg/L of nickel, and the experimental results are shown in Table 3 below.

TABLE 3 sodium sulfate vs. Nickel masking experiment

As can be seen from Table 3 above, when the concentration of sodium sulfate in the solution to be measured is 3.0-4.0 g/L, the interference of nickel on chromium can be completely eliminated.

Influence of sodium sulfate addition on iron element

Different sodium sulfate solutions were added to the chromium standard solutions of 0.25mg/L and 1.00mg/L, respectively, each having an iron content of 100mg/L, and the experimental results are shown in Table 4 below.

TABLE 4 sodium sulfate versus iron masking experiment

As can be seen from Table 4 above, when the concentration of sodium sulfate in the solution to be measured is 3.0-5.0 g/L, the interference of iron on chromium can be completely eliminated.

Therefore, the interference elimination experiment of nickel and iron is considered, and the concentration of sodium sulfate in the solution to be detected is 4.0 g/L.

Comparison of operating curves

And respectively preparing a water and chromium standard working curve and a nickel and iron matrix matching chromium standard working curve, respectively adding 80 g/L5 mL of sodium sulfate solution, and determining results shown in the following table 5.

TABLE 5 comparison of chromium working curves

As can be seen from the data in Table 5, the absorbance of the two working curves is consistent, and the interference of nickel and iron is completely eliminated after the sodium sulfate is added, so that the water mark working curve added with the sodium sulfate can be used for replacing the matching working curve of the nickel and iron matrixes.

Hydrochloric acid medium concentration selection

Preparing 0.25mg/L and 1.00mg/L chromium standard solutions, adding 80g/L sodium sulfate solution 5mL, and adding different hydrochloric acid amounts, wherein the absorbance values are shown in Table 6.

TABLE 6 hydrochloric acid medium concentration selection

As can be seen from Table 6, the difference in hydrochloric acid concentration affects the determination of chromium element, and 20% hydrochloric acid concentration was selected as the formulated acid concentration of the calibration curve in order to keep the acidity of the solution to be measured.

Method detection limit

The concentration of the blank was measured for 11 samples according to the experimental method, using 3 times the standard deviation of the measured values as the detection limit of the method, and the concentration corresponding to 10 times the standard deviation as the lower measurement limit, as shown in Table 7 below.

TABLE 7 determination of detection limits and lower measurement limits

As is clear from Table 7, the detection limit of this method is 0.014mg/L, and the lower limit of the method measurement is 0.046 mg/L.

Test for recovery with addition of standard

Different amounts of chromium standard solutions were added to the samples, respectively, and the standard recovery experiments were performed according to the experimental methods, the results of which are shown in table 8.

TABLE 8 spiking recovery experiment

The data in table 8 show that the normalized recovery of chromium in the samples ranged from 90.0% to 102.0%. The method has good recovery rate of the added standard and meets the production requirement of a nickel system.

Multiple ratio test

The chromium content of the mixed anolyte was determined using different sample volumes according to the experimental method of this example, and the results are shown in table 9 below.

TABLE 9 control of mixed anolyte results

17. Control experiment

The method comprises the steps of weighing 0.1000g of sample nickel hydroxide, dissolving in alkali, metering to a volume of 200mL, and taking 50mL of the sample to perform determination by the method.

TABLE 10 control experiment