A method for determining palladium content in palladium ash

Abstract

The present invention relates to a method for determining the content of palladium in palladium ash, and belongs to the technical field of secondary resource detection of precious metals. The present invention mixes palladium ash and a mixed oxidant for melting decomposition, leaches with dilute hydrochloric acid, and boils after adding nitric acid to obtain a palladium ash sample solution, the palladium ash sample solution is precipitated by dimethylglyoxime under acidic conditions, and then dissolved by hydrochloric acid-hydrogen peroxide to prepare a palladium test solution; a palladium standard stock solution is transferred, a palladium standard working solution is prepared, and the concentration of the palladium standard working solution is determined by an inductively coupled plasma emission spectrometer to construct a standard working curve; according to the standard working curve, the palladium ion concentration of the palladium test solution is determined by an inductively coupled plasma emission spectrometer, and then the palladium content in the palladium ash is calculated. The present invention enhances the decomposition ability of the sample, can solve the problems of limited palladium capture capacity and incomplete impurity separation in the existing method, and significantly improves the accuracy of the palladium determination result.

Description

Technical Field

[0001] The invention relates to a method for determining the palladium content in palladium ash, and belongs to the technical field of precious metal secondary resource detection. Background Art

[0002] Palladium ash is a by-product in the recovery process of palladium-containing materials. Rapid and accurate analysis of the palladium content in palladium ash can provide a strong guarantee for improving the recovery rate of palladium in secondary resources. The palladium content in palladium ash is usually low. The current determination methods mainly include tellurium coprecipitation method, fire assay method, closed digestion method, etc. In fact, the tellurium coprecipitation method and fire assay method have limited capture capacity for palladium. When the palladium content is relatively high, the palladium cannot be completely captured, resulting in low test results; the closed digestion method has the phenomenon of dissolving residues in the palladium ash sample, and it is impossible to judge whether the palladium is completely dissolved, which affects the test results; if the palladium content is directly determined after alkaline melt leaching, the large amount of sodium ions and other impurity elements in the solution will have a great interference with the instrument measurement. In addition, the presence of a large amount of sodium salt will also clog the instrument, ultimately affecting the test results. In summary, the existing methods for the determination of low-content palladium ash have shortcomings, mainly manifested in weak sample decomposition ability, limited palladium capture ability, and incomplete impurity separation that interferes with the determination. Summary of the invention

[0003] In the determination of low-content palladium ash, there are problems such as weak sample decomposition ability, limited palladium capture ability, and incomplete impurity separation interfering with the determination. The present invention proposes a method for determining the palladium content in palladium ash. The present invention mixes palladium ash and a mixed oxidant for melting decomposition, leaches with dilute hydrochloric acid, and boils after adding nitric acid to obtain a palladium ash sample solution. The palladium ash sample solution is precipitated with dimethylglyoxime under acidic conditions, and then dissolved with hydrochloric acid-hydrogen peroxide to prepare a palladium test solution; the palladium standard stock solution is transferred, a palladium standard working solution is prepared, and the concentration of the palladium standard working solution is determined by an inductively coupled plasma emission spectrometer to construct a standard working curve; according to the standard working curve, the palladium ion concentration of the palladium test solution is determined by an inductively coupled plasma emission spectrometer, and then the palladium content in the palladium ash is calculated. The present invention enhances the decomposition ability of the sample, can solve the problems of limited palladium capture ability and incomplete impurity separation in the existing method, and significantly improves the accuracy of the palladium determination results.

[0004] A method for determining the palladium content in palladium ash, the specific steps are as follows:

[0005] (1) adding a weighed amount of palladium ash into a high-aluminum crucible, adding a mixed oxidant and mixing, melting at a temperature of 770-790°C, cooling to room temperature, directly adding the high-aluminum crucible into a dilute hydrochloric acid solution, leaching the melt in the high-aluminum crucible at room temperature, washing the high-aluminum crucible with deionized water to obtain a leachate, adding nitric acid to the leachate and heating it to a slight boil, cooling to room temperature, and diluting with deionized water to obtain a palladium ash sample solution;

[0006] (2) Pd ash sample solution was transferred and evaporated at room temperature to wet salt state, deionized water and dimethylglyoxime-acetone mixture were added, stirred until the precipitate was completely precipitated and allowed to stand, filtered through medium-speed quantitative filter paper for separation, and the palladium precipitate on the filter paper was washed with ammonia diluent;

[0007] (3) Evaporating the palladium precipitate at room temperature, adding hydrochloric acid and hydrogen peroxide to dissolve it, cooling it, and using deionized water to make up the volume to obtain a palladium test solution;

[0008] (4) Accurately pipette the palladium standard stock solution and prepare palladium standard working solutions with concentrations of 0.00, 0.50, 1.00, 10.00, 20.00, and 30.00 g / mL, respectively;

[0009] (5) Determine the concentration of the palladium standard working solution using an inductively coupled plasma emission spectrometer and construct a standard working curve;

[0010] (6) According to the standard working curve, the palladium ion concentration of the palladium test solution is determined by inductively coupled plasma emission spectrometry, and then the palladium content in the palladium ash is calculated.

[0011] The mass of palladium ash weighed in step (1) is 0.5-2 g.

[0012] The mixed oxidant in step (1) is a mixture of sodium hydroxide and sodium peroxide, and the molar ratio of sodium hydroxide to sodium peroxide is 1:1-1.5.

[0013] The amount of the mixed oxidant added in step (1) is 2 to 6 times the mass of the palladium ash.

[0014] The concentration of the dilute hydrochloric acid solution in step (1) is 1.2-2.4 mol / L.

[0015] The concentration of nitric acid in step (1) is 14.4-15.2 mol / L, and the amount of nitric acid added is 5-10% of the volume of the leaching solution.

[0016] The amount of deionized water added in step (2) is 5 to 10 times the volume of the palladium ash sample solution removed, the concentration of dimethylglyoxime in the dimethylglyoxime-acetone mixture is 3 to 9 g / L, and the amount of dimethylglyoxime-acetone mixture added is 1 to 2 times the volume of the palladium ash sample solution removed.

[0017] The NH3 concentration in the ammonia dilution solution in step (2) is 13.3-14.8 mol / L.

[0018] In the step (3), the concentration of hydrochloric acid is 11.6-12.4 mol / L, the mass concentration of hydrogen peroxide is 20-30%, the liquid-solid ratio of hydrochloric acid to the evaporated palladium precipitate is 6-9:1 in mL:mg, and the liquid-solid ratio of hydrogen peroxide to the evaporated palladium precipitate is 2-3:1 in mL:mg.

[0019] The calculation formula for the palladium content in the palladium ash in step (6) is:

[0020] ;

[0021] Where:

[0022] W%-mass fraction of palladium content, %; C-palladium concentration after deducting blank from the measured concentration in step (4), g / mL; V1-volume of solution in step (1), mL; V2-volume of solution removed in step (2), mL; V3-volume of solution in step (3), mL; m-weight of sample, g.

[0023] The beneficial effects of the present invention are:

[0024] (1) The present invention adopts a method of high-temperature melting of a palladium ash sample and a mixed strong oxidant, and then acid leaching to enhance the decomposition ability of the palladium ash sample;

[0025] (2) The palladium ash sample of the present invention has a large sample weight, which can improve the representativeness, stability and accuracy of the test results;

[0026] (3) The present invention uses dimethylglyoxime mixed reagent and palladium chelate precipitation and then performs solid-liquid separation, which can completely separate the palladium and impurities in the palladium ash, solve the problem of insufficient palladium capture capacity and incomplete impurity separation in the existing method, and further improve the accuracy of detection;

[0027] (4) The present invention uses hydrochloric acid-hydrogen peroxide to quickly decompose dimethylglyoxime palladium precipitate, and then determines the palladium content by inductively coupled plasma emission spectroscopy, which has the characteristics of accurate results, high efficiency, strong applicability, and easy to master. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is the standard working curve. DETAILED DESCRIPTION

[0029] The present invention is further described in detail below in conjunction with specific implementation modes, but the protection scope of the present invention is not limited to the described contents.

[0030] Example 1: A palladium ash No. 1 sample with a palladium content standard value of 0.51% (mass fraction) was measured 9 times and the average value and relative standard deviation were calculated;

[0031] The method for determining the palladium content in palladium ash, the specific steps are as follows:

[0032] (1) 2 g of palladium ash (accurate to 0.0001 g) was weighed and added into a high-aluminum crucible, and a mixed oxidant (a mixture of sodium hydroxide and sodium peroxide, with a molar ratio of sodium hydroxide to sodium peroxide of 1:1) was added and mixed, and melted at a temperature of 770°C for 10 min, cooled to room temperature, and the high-aluminum crucible was directly added into a dilute hydrochloric acid solution with a concentration of 1.2 mol / L, and the melt in the high-aluminum crucible was leached at room temperature, and the high-aluminum crucible was washed with deionized water to obtain a leachate, and nitric acid with a concentration of 14.5 mol / L was added to the leachate and heated to a slight boil, cooled to room temperature, transferred to a volumetric flask and fixed to volume with deionized water to obtain a palladium ash sample solution; the amount of the mixed oxidant added was twice the mass of the palladium ash, and the amount of nitric acid added was 5% of the volume of the leachate;

[0033] (2) Pipette 10 mL of palladium ash sample solution, evaporate it at room temperature to a wet salt state, add deionized water and dimethylglyoxime-acetone mixed solution (the concentration of dimethylglyoxime in the dimethylglyoxime-acetone mixed solution is 3 g / L), stir until the precipitate is completely precipitated and let stand for 30 minutes, filter and separate through medium-speed quantitative filter paper, and wash the palladium precipitate on the filter paper with ammonia diluent (the concentration of NH3 in the ammonia diluent is 13.6 mol / L); the amount of deionized water added is 5 times the volume of the palladium ash sample solution transferred, and the amount of dimethylglyoxime-acetone mixed solution added is 1 times the volume of the palladium ash sample solution transferred;

[0034] (3) Evaporating the palladium precipitate at room temperature, adding 11.9 mol / L hydrochloric acid and 30% mass concentration of hydrogen peroxide to dissolve, cooling, transferring to a volumetric flask and making up to volume with deionized water to obtain a palladium test solution; the liquid-solid ratio of the hydrochloric acid to the evaporated palladium precipitate is 6:1, and the liquid-solid ratio of the hydrogen peroxide to the evaporated palladium precipitate is 2:1;

[0035] (4) Accurately pipette 1000 g / mL palladium standard stock solution and prepare palladium standard working solutions with concentrations of 0.00, 0.50, 1.00, 10.00, 20.00, and 30.00 g / mL, respectively;

[0036] (5) The concentration of the palladium standard working solution (wavelength 340.458 nm) was determined by inductively coupled plasma emission spectrometry, and a standard working curve was constructed. Specifically, under the optimal working conditions of nebulizing gas flow rate 0.9 L / min, auxiliary gas flow rate 0.7 L / min, plasma gas flow rate 15 L / min, solution lifting volume 1.0 L / min, high frequency power 1300 W, measurement repetition number 3, measurement time 30 s, axial observation, peak area integral calculation results, a wavelength of 340.458 nm was selected to establish the standard working curve, and the correlation linear coefficient r ≥ 0.9999, see Figure 1 ;

[0037] (6) According to the standard working curve, the palladium ion concentration of the palladium test solution is determined by inductively coupled plasma emission spectrometry, and then the palladium content in the palladium ash is calculated;

[0038] The calculation formula of the palladium content in the palladium ash is:

[0039] ;

[0040] Where: W%-mass fraction of palladium content, %; C-palladium concentration after deducting blank from the measured concentration in step (4), g / mL; V1-volume of solution in step (1), mL; V2-volume of solution removed in step (2), mL; V3-volume of solution in step (3), mL; m-weight of sample, g;

[0041] The results of 9 measurements of palladium ash No. 1 sample in this embodiment (palladium content in palladium ash) and their average values ​​and relative standard deviations are shown in Table 1.

[0042] Table 1 Determination results of palladium content in palladium ash sample 1# and average value and relative standard deviation

[0043] ;

[0044] As can be seen from Table 1, the palladium ash sample in this embodiment has a large sample weight (2 g), a good decomposition effect, a strong palladium capture ability, and a thorough impurity separation, which improves the accuracy of the determination of the palladium content in the palladium ash, and the relative standard deviation is only 1.18%.

[0045] Example 2: A palladium ash 2# sample with a standard palladium content of 1.13% (mass fraction) was measured 9 times and the average value and relative standard deviation were calculated;

[0046] The method for determining the palladium content in palladium ash, the specific steps are as follows:

[0047] (1) 1.5 g of palladium ash (accurate to 0.0001 g) was weighed and added to a high-aluminum crucible, and a mixed oxidant (a mixture of sodium hydroxide and sodium peroxide, with a molar ratio of sodium hydroxide to sodium peroxide of 1:1.2) was added and mixed, melted at a temperature of 780°C for 10 min, cooled to room temperature, and the high-aluminum crucible was directly added to a dilute hydrochloric acid solution with a concentration of 1.2 mol / L, and the melt in the high-aluminum crucible was leached at room temperature, and the high-aluminum crucible was washed with deionized water to obtain a leachate, nitric acid with a concentration of 14.5 mol / L was added to the leachate and heated to a slight boil, cooled to room temperature, transferred to a volumetric flask and fixed to volume with deionized water to obtain a palladium ash sample solution; the amount of the mixed oxidant added was 3 times the mass of the palladium ash, and the amount of nitric acid added was 5% of the volume of the leachate;

[0048] (2) Pipette 10 mL of palladium ash sample solution, evaporate it at low temperature at room temperature until it is in a wet salt state, add deionized water and dimethylglyoxime-acetone mixed solution (the concentration of dimethylglyoxime in the dimethylglyoxime-acetone mixed solution is 5 g / L), stir until the precipitate is completely precipitated and let stand for 30 minutes, filter and separate through medium-speed quantitative filter paper, and wash the palladium precipitate on the filter paper with ammonia diluent (the concentration of NH3 in the ammonia diluent is 13.6 mol / L); the amount of deionized water added is 5 times the volume of the palladium ash sample solution transferred, and the amount of dimethylglyoxime-acetone mixed solution added is 1 times the volume of the palladium ash sample solution transferred;

[0049] (3) Evaporating the palladium precipitate at room temperature, adding 1.2 mol / L hydrochloric acid and 30% mass concentration of hydrogen peroxide to dissolve, cooling, transferring to a volumetric flask and making up to volume with deionized water to obtain a palladium test solution; the liquid-solid ratio of the hydrochloric acid to the evaporated palladium precipitate is 6:1, and the liquid-solid ratio of the hydrogen peroxide to the evaporated palladium precipitate is 2:1;

[0050] (4) Accurately pipette 1000 g / mL palladium standard stock solution and prepare palladium standard working solutions with concentrations of 0.00, 0.50, 1.00, 10.00, 20.00, and 30.00 g / mL, respectively;

[0051] (5) The concentration of the palladium standard working solution (wavelength 340.458 nm) was determined by inductively coupled plasma emission spectrometry, and a standard working curve was constructed. Figure 1 ;

[0052] (6) According to the standard working curve, the palladium ion concentration of the palladium test solution is determined by inductively coupled plasma emission spectrometry, and then the palladium content in the palladium ash is calculated;

[0053] The results of 9 measurements of palladium ash No. 2 sample in this embodiment (palladium content in palladium ash) and their average values ​​and relative standard deviations are shown in Table 2.

[0054] Table 2 Determination results of palladium content in palladium ash sample 2# and average value and relative standard deviation

[0055] ;

[0056] As can be seen from Table 2, the palladium ash sample in this embodiment has a large sample weight (1.5 g), a good decomposition effect, a strong palladium capture ability, and a thorough impurity separation, which improves the accuracy of the determination of the palladium content in the palladium ash, and the relative standard deviation is only 1.97%.

[0057] Example 3: A palladium ash 3# sample with a standard palladium content of 2.66% (mass fraction) was measured 9 times and the average value and relative standard deviation were calculated;

[0058] The method for determining the palladium content in palladium ash, the specific steps are as follows:

[0059] (1) 1.0 g of palladium ash (accurate to 0.0001 g) was weighed and added into a high-aluminum crucible, and a mixed oxidant (a mixture of sodium hydroxide and sodium peroxide, with a molar ratio of sodium hydroxide to sodium peroxide of 1:1.2) was added and mixed, and melted at a temperature of 790°C for 10 min, cooled to room temperature, and the high-aluminum crucible was directly added into a dilute hydrochloric acid solution with a concentration of 1.2 mol / L, and the melt in the high-aluminum crucible was leached at room temperature, and the high-aluminum crucible was washed with deionized water to obtain a leachate, and nitric acid with a concentration of 14.5 mol / L was added to the leachate and heated to a slight boil, cooled to room temperature, transferred to a volumetric flask and fixed to volume with deionized water to obtain a palladium ash sample solution; the amount of the mixed oxidant added was 4 times the mass of the palladium ash, and the amount of nitric acid added was 10% of the volume of the leachate;

[0060] (2) Take 5 mL of palladium ash sample solution, evaporate it at low temperature at room temperature until it is in a wet salt state, add deionized water and dimethylglyoxime-acetone mixed solution (the concentration of dimethylglyoxime in the dimethylglyoxime-acetone mixed solution is 7 g / L), stir until the precipitate is completely precipitated and let it stand for 30 minutes, filter and separate it through medium-speed quantitative filter paper, and use ammonia diluent (the NH3 concentration in the ammonia diluent is 13.6 mol / L) to wash the palladium precipitate on the filter paper; the amount of deionized water added is 10 times the volume of the palladium ash sample solution taken, and the amount of dimethylglyoxime-acetone mixed solution added is 2 times the volume of the palladium ash sample solution taken;

[0061] (3) Evaporating the palladium precipitate at room temperature, adding 1.2 mol / L hydrochloric acid and 30% mass concentration of hydrogen peroxide to dissolve it, cooling it, transferring it to a volumetric flask and making up the volume with deionized water to obtain a palladium test solution; the liquid-solid ratio of the hydrochloric acid to the evaporated palladium precipitate is 9:1, and the liquid-solid ratio of the hydrogen peroxide to the evaporated palladium precipitate is 3:1;

[0062] (4) Accurately pipette 1000 g / mL palladium standard stock solution and prepare palladium standard working solutions with concentrations of 0.00, 0.50, 1.00, 10.00, 20.00, and 30.00 g / mL, respectively;

[0063] (5) The concentration of the palladium standard working solution (wavelength 340.458 nm) was determined by inductively coupled plasma emission spectrometry, and a standard working curve was constructed. Figure 1 ;

[0064] (6) According to the standard working curve, the palladium ion concentration of the palladium test solution is determined by inductively coupled plasma emission spectrometry, and then the palladium content in the palladium ash is calculated;

[0065] The results of 9 measurements of palladium ash 3# sample in this embodiment (palladium content in palladium ash) and their average values ​​and relative standard deviations are shown in Table 3.

[0066] Table 3 Determination results of palladium content in palladium ash sample 3# and average value and relative standard deviation

[0067] ;

[0068] As can be seen from Table 3, the palladium ash sample of this invention has a large sample weight (1.0 g), a good decomposition effect, a strong palladium capture ability, and a thorough impurity separation, which improves the accuracy of the determination of the palladium content in the palladium ash, and the relative standard deviation is only 1.80%.

[0069] Example 4: A palladium ash 4# sample with a palladium content standard value of 4.76% (mass fraction) was measured 9 times and the average value and relative standard deviation were calculated;

[0070] The method for determining the palladium content in palladium ash, the specific steps are as follows:

[0071] (1) Add 0.5 g of palladium ash (accurate to 0.0001 g) weighed into a high-aluminum crucible, add a mixed oxidant (a mixture of sodium hydroxide and sodium peroxide, with a molar ratio of sodium hydroxide to sodium peroxide of 1:1.5) and mix well, melt at a temperature of 780°C for 10 min, cool to room temperature, directly add the high-aluminum crucible into a dilute hydrochloric acid solution with a concentration of 1.2 mol / L, and leach the melt in the high-aluminum crucible at room temperature. Wash the high-aluminum crucible with deionized water to obtain a leachate, add nitric acid with a concentration of 14.5 mol / L to the leachate and heat to a slight boil, cool to room temperature, transfer to a volumetric flask and dilute to volume with deionized water to obtain a palladium ash sample solution; the amount of the mixed oxidant added is 6 times the mass of the palladium ash, and the amount of nitric acid added is 10% of the volume of the leachate;

[0072] (2) Take 5 mL of palladium ash sample solution, evaporate it at low temperature at room temperature until it is in a wet salt state, add deionized water and dimethylglyoxime-acetone mixed solution (the concentration of dimethylglyoxime in the dimethylglyoxime-acetone mixed solution is 9 g / L), stir until the precipitate is completely precipitated and let it stand for 30 minutes, filter and separate it through medium-speed quantitative filter paper, and use ammonia diluent (the NH3 concentration in the ammonia diluent is 13.6 mol / L) to wash the palladium precipitate on the filter paper; the amount of deionized water added is 10 times the volume of the palladium ash sample solution taken, and the amount of dimethylglyoxime-acetone mixed solution added is 2 times the volume of the palladium ash sample solution taken;

[0073] (3) Evaporating the palladium precipitate at room temperature, adding 1.2 mol / L hydrochloric acid and 30% mass concentration of hydrogen peroxide to dissolve it, cooling it, transferring it to a volumetric flask and making up the volume with deionized water to obtain a palladium test solution; the liquid-solid ratio of the hydrochloric acid to the evaporated palladium precipitate is 9:1, and the liquid-solid ratio of the hydrogen peroxide to the evaporated palladium precipitate is 3:1;

[0074] (4) Accurately pipette 1000 g / mL palladium standard stock solution and prepare palladium standard working solutions with concentrations of 0.00, 0.50, 1.00, 10.00, 20.00, and 30.00 g / mL, respectively;

[0075] (5) The concentration of the palladium standard working solution (wavelength 340.458 nm) was determined by inductively coupled plasma emission spectrometry, and a standard working curve was constructed. Figure 1 ;

[0076] (6) According to the standard working curve, the palladium ion concentration of the palladium test solution is determined by inductively coupled plasma emission spectrometry, and then the palladium content in the palladium ash is calculated;

[0077] The results of 9 measurements of palladium ash No. 4 sample in this embodiment (palladium content in palladium ash) and their average values ​​and relative standard deviations are shown in Table 4.

[0078] Table 4 Determination results of palladium content in palladium ash 4# sample and average value and relative standard deviation

[0079] ;

[0080] As can be seen from Table 4, the palladium ash sample of this invention has a large sample weight (0.5 g), a good decomposition effect, a strong palladium capture ability, and a thorough impurity separation, which improves the accuracy of the determination of the palladium content in the palladium ash, and the relative standard deviation is only 1.46%.

[0081] The specific implementation modes of the present invention are described in detail above, but the present invention is not limited to the above implementation modes, and various changes can be made within the knowledge scope of ordinary technicians in this field without departing from the purpose of the present invention.

Claims

1. A method for determining the palladium content in palladium ash, characterized in that: The specific steps are as follows: (1) adding a weighed amount of palladium ash into a high-aluminum crucible, adding a mixed oxidant and mixing, melting at a temperature of 770-790°C, cooling to room temperature, directly adding the high-aluminum crucible into a dilute hydrochloric acid solution, leaching the melt in the high-aluminum crucible at room temperature, washing the high-aluminum crucible with deionized water to obtain a leachate, adding nitric acid to the leachate and heating it to a slight boil, cooling to room temperature, and fixing the volume with deionized water to obtain a palladium ash sample solution; the mixed oxidant is a mixture of sodium hydroxide and sodium peroxide, and the molar ratio of sodium hydroxide to sodium peroxide is 1:1-1.5; (2) Pd ash sample solution was transferred and evaporated at room temperature to wet salt state, deionized water and dimethylglyoxime-acetone mixture were added, stirred until the precipitate was completely precipitated and allowed to stand, filtered through medium-speed quantitative filter paper for separation, and the palladium precipitate on the filter paper was washed with ammonia diluent; (3) Evaporating the palladium precipitate at room temperature, adding hydrochloric acid and hydrogen peroxide to dissolve it, cooling it, and using deionized water to make up the volume to obtain a palladium test solution; (4) Accurately pipette the palladium standard stock solution and prepare palladium standard working solutions with concentrations of 0.00, 0.50, 1.00, 10.00, 20.00, and 30.00 µg / mL, respectively; (5) Determine the concentration of the palladium standard working solution using an inductively coupled plasma emission spectrometer and construct a standard working curve; (6) According to the standard working curve, the palladium ion concentration of the palladium test solution is determined by inductively coupled plasma emission spectrometry, and then the palladium content in the palladium ash is calculated.

2. The method for measuring the palladium content in the palladium ash according to claim 1, wherein: The amount of the mixed oxidant added in step (1) is 2 to 6 times the mass of the palladium ash.

3. The method for measuring the palladium content in the palladium ash according to claim 1, wherein: The concentration of the dilute hydrochloric acid solution in step (1) is 1.2-2.4 mol / L.

4. The method for measuring the palladium content in the palladium ash according to claim 1, wherein: The concentration of nitric acid in step (1) is 14.4-15.2 mol / L, and the amount of nitric acid added is 5-10% of the volume of the leaching solution.

5. The method for measuring the palladium content in the palladium ash according to claim 1, wherein: The amount of deionized water added in step (2) is 5 to 10 times the volume of the palladium ash sample solution transferred, the concentration of dimethylglyoxime in the dimethylglyoxime-acetone mixture is 3 to 9 g / L, and the amount of dimethylglyoxime-acetone mixture added is 1 to 2 times the volume of the palladium ash sample solution transferred.

6. The method for measuring the palladium content in the palladium ash according to claim 1, wherein: The NH3 concentration in the ammonia dilution solution of step (2) is 13.3-14.8 mol / L.

7. The method for determining the palladium content in palladium ash according to claim 1, wherein: In step (3), the concentration of hydrochloric acid is 11.6-12.4 mol / L, the mass concentration of hydrogen peroxide is 20-30%, the liquid-solid ratio of hydrochloric acid to the evaporated palladium precipitate is 6-9:1 in mL:mg, and the liquid-solid ratio of hydrogen peroxide to the evaporated palladium precipitate is 2-3:1 in mL:mg.

8. The method for measuring the palladium content in palladium ash according to claim 1, wherein: The calculation formula for the palladium content in the palladium ash in step (6) is: ； Where: W%-mass fraction of palladium content, %; C-palladium concentration after deducting blank from the measured concentration in step (4), µg / mL; V1-volume of solution in step (1), mL; V2-volume of solution removed in step (2), mL; V3-volume of solution in step (3), mL; m-weight of sample, g.

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