A chemical analysis method for determining chloride ions in metallic copper by generating molecular crystals to constrain the behavior of specific ions

Abstract

The invention belongs to the field of chemical analysis, and specifically discloses a chemical analysis method for determining chloride ions in metallic copper by generating molecular crystals to constrain the behavior of specific ions. The invention well solves the problem of determining the chloride ion content in metal-containing samples and has simple operation and high accuracy.

Description

Technical Field

[0001] The invention belongs to the field of chemical analysis, and relates to a method for determining chloride ions, and in particular to a chemical analysis method for determining chloride ions in metallic copper by utilizing the generation of molecular crystals to constrain the behavior of specific ions. Background Art

[0002] During the smelting process, crude copper is further smelted from matte. Since its impurity element content is still relatively high, it cannot be used directly and is generally used as the raw material for electrolytic copper. During the copper beneficiation process, copper oxide minerals will not be floated and are therefore stripped out. Generally, it is oxidized and leached with acid. After the copper ions enter the leaching solution, they are reduced to produce crude copper powder. This powder has a high impurity element content and cannot be used directly. It requires further smelting and purification.

[0003] The above two types of copper metals generally contain considerable concentrations of chloride ions. If they are not removed during further smelting and purification, the chloride ions will affect the product quality of the copper during electrolysis, and may even have a destructive effect on the production equipment. Therefore, before further smelting and purification of the above two types of copper metals, it is necessary to understand the specific content of chloride ions therein. Since most of the chloride ions are melted as chloride salts and wrapped inside the copper metal, chemical detection of the chloride ion content in the copper metal becomes a difficult point.

[0004] The most mature dissolution method for testing chloride ions is the semi-sintering method of Eska reagent. However, this method is more effective for natural mineral or compound samples, and has little effect on samples mainly composed of metals. The main reason is that during the sintering process, the insoluble chloride salts are all converted into carbonates with a smaller volume, so that the chloride ions are converted into water-soluble sodium chloride for leaching; since the conversion rate of chloride salts wrapped in metals is relatively low, this method is not suitable for the determination of chloride ions in metal-containing samples.

[0005] In addition, if the acid dissolution method is directly used for leaching of the above two types of copper samples, the chloride ions wrapped by the metal can be released. However, during the dissolution process, due to the need for heating and the heat release of the chemical reaction itself during the reaction, the free chloride ions dissociated in the solution will be volatilized and lost in the form of hydrogen chloride, resulting in low analysis results. Summary of the invention

[0006] The invention provides a chemical analysis method which is simple to operate and highly accurate and which utilizes the generation of molecular crystals to constrain the behavior of specific ions to determine chloride ions in metallic copper.

[0007] To achieve the above object, the present invention adopts the following technical solutions:

[0008] A chemical analysis method for determining chloride ions in metallic copper by generating molecular crystals to constrain the behavior of specific ions, characterized in that it comprises the following steps:

[0009] (1) Weigh 1.000-3.0000g of metallic copper sample and place it in a 400mL beaker. Add 50mL of 1:2 dilute nitric acid containing 10g / L of mercuric nitrate. Heat the sample to completely dissolve it. Boil it to drive out all nitrogen oxides. Remove it and cool it.

[0010] (2) Add ammonia water to the solution obtained in step (1) and stir, adjust its pH value to about 9, add 5-10 mL of excess ammonia water, and let it stand for 1-2 hours;

[0011] (3) Filter the solution after standing in step (2), wash the beaker and the precipitate with 1:19 nitric acid for 6-7 times respectively, retain the precipitate, discard the filtrate, put the filter paper together with the precipitate into the washed beaker, add nitric acid and sulfuric acid mixed acid for treatment, prepare a 1:9 hydrochloric acid solution, determine the mercury by ICP method after constant volume, and convert the chloride ion content. The amount of mercury to chloride ion in the aminomercuric chloride compound is 1:2.

[0012] Preferably, in step (3), slow filter paper is used for filtration.

[0013] Preferably, the nitric acid used in step (3) is 15 mol / L, and the ammonia water used in step (2) is 15 mol / L.

[0014] The present invention adopts a method of acid dissolution to simultaneously dissociate the free chloride ions in the solution to form a molecular crystal that is not easy to lose, so as to constrain the chemical behavior of the chloride ions in the solution and fix the chloride ions in the solution, and then separate the chloride by other methods, and then determine the content of the chloride ions; the present invention adopts 1:2 nitric acid and 10g / L mercuric nitrate to dissolve the sample, so that the chloride ions are dissociated and at the same time form mercuric chloride molecular crystals, thereby constraining the ionic behavior of the free chloride ions in the solution and fixing them in the solution; the sample is dissolved by using dilute nitric acid and mercuric nitrate at the same time, so that the free chloride ions in the solution are dissociated and at the same time form mercuric chloride molecular crystals. The method can form mercuric dichloride molecular crystals, thus solving the problem of free chloride ion volatilization loss in the solution process; after the sample is completely dissolved, ammonia water is added to adjust the pH value of the solution to about 9 in excess, so that the mercuric dichloride molecular crystals generate aminomercuric dichloride precipitates, which is a characteristic reaction of mercuric dichloride ion crystals, and then separate from the copper ions in the solution, retain the precipitates, and determine the mercury content after dissolving it, and indirectly calculate the chloride ion content, and ammonia water is added to make the mercuric dichloride molecular crystals generate aminomercuric chloride precipitates and separate from a large amount of copper ions in the solution, thereby avoiding the influence of the copper ion matrix effect in the subsequent mercury testing process, and improving the accuracy and reliability of the measurement results.

[0015] The invention has the advantages of simple operation and high accuracy, and has been applied in actual detection work. The invention well solves the determination of chloride ion content in metal-containing samples and fills the blank of analysis and detection in this field in China. DETAILED DESCRIPTION

[0016] Example 1

[0017] A chemical analysis method for determining chloride ions in metallic copper by generating molecular crystals to constrain the behavior of specific ions, comprising the following steps:

[0018] (1) Weigh about 1.000g of metallic copper sample into a 400mL beaker, add 50mL of 1:2 dilute nitric acid containing 10g / L of mercuric nitrate, heat to completely dissolve the sample, boil to drive out nitrogen oxides, and remove to cool;

[0019] (2) Adding aqueous ammonia to the cooled solution in step (1) while stirring, adjusting the pH of the solution to about 9, and adding 5-10 mL of excess aqueous ammonia, and letting it stand for 1-2 hours;

[0020] The solution after standing in step (2) is filtered using slow filter paper, and the beaker and the precipitate are washed with 1:19 nitric acid for 6-7 times respectively, the precipitate is retained, and the filtrate is discarded, and the filter paper and the precipitate are placed in the original beaker, and treated with a nitric acid and sulfuric acid mixed acid with a volume ratio of 2:1, and then prepared into a 1:9 hydrochloric acid solution. After constant volume, the mercury is determined by ICP, and then converted into the content of chloride ions. The amount of mercury and chloride ions in the aminomercuric chloride compound is 1:2; the chemical reagents used in the test method adopted by the present invention are all analytical pure reagents, nitric acid is 15 mol / L, and ammonia water is 15 mol / L; the spiked recovery and precision of this example are shown in Table 1 below.

[0021]

[0022] Example 2

[0023] A chemical analysis method for determining chloride ions in metallic copper by generating molecular crystals to constrain the behavior of specific ions, comprising the following steps:

[0024] (1) Weigh about 2.000g of metallic copper sample into a 400mL beaker, add 50mL of 1:2 dilute nitric acid containing 10g / L of mercuric nitrate, heat to completely dissolve the sample, boil to drive out nitrogen oxides, and remove to cool;

[0025] (2) Adding aqueous ammonia to the cooled solution in step (1) while stirring, adjusting the pH of the solution to about 9, and adding 5-10 mL of excess aqueous ammonia, and letting it stand for 1-2 hours;

[0026] (3) The solution after standing in step (2) was filtered using slow filter paper, and the beaker and the precipitate were washed with 1:19 nitric acid for 6-7 times respectively. The precipitate was retained and the filtrate was discarded. The filter paper and the precipitate were placed in the original beaker, and after treatment with nitric acid and sulfuric acid mixed acid, a 1:9 hydrochloric acid solution was prepared. After constant volume, the mercury was determined by ICP, and then converted into the chloride ion content. The amount of mercury and chloride ion in the aminomercuric chloride compound was 1:2. The spiked recovery and precision of this example are shown in Table 2 below.

[0027]

[0028] Example 3

[0029] A chemical analysis method for determining chloride ions in metallic copper by generating molecular crystals to constrain the behavior of specific ions, comprising the following steps:

[0030] (1) Weigh about 3.000g of metallic copper sample into a 400mL beaker, add 50mL of 1:2 dilute nitric acid (containing 10g / L of mercuric nitrate), heat to completely dissolve the sample, boil to drive out nitrogen oxides, and remove to cool;

[0031] (2) Adding aqueous ammonia to the cooled solution in step (1) while stirring, adjusting the pH of the solution to about 9, and adding 5-10 mL of excess aqueous ammonia, and letting it stand for 1-2 hours;

[0032] (3) The solution after standing in step (2) was filtered using slow filter paper, and the beaker and the precipitate were washed with 1:19 nitric acid for 6-7 times respectively. The precipitate was retained and the filtrate was discarded. The filter paper and the precipitate were placed in the original beaker, and after treatment with nitric acid and sulfuric acid mixed acid, a 1:9 hydrochloric acid solution was prepared. After constant volume, the mercury was determined by ICP, and then converted into the chloride ion content. The amount of mercury and chloride ion in the aminomercuric chloride compound was 1:2. The spiked recovery and precision of this example are shown in Table 3 below.

[0033]

Claims

1. A chemical analysis method for determining chloride ions in metallic copper by generating molecular crystals to constrain the behavior of specific ions, characterized in that: The following steps are involved: (1) Weigh about 1.000g of metallic copper sample into a 400mL beaker, add 50mL of 1:2 dilute nitric acid containing 10g / L of mercuric nitrate, heat to completely dissolve the sample, boil to drive out nitrogen oxides, and remove to cool; (2) Adding aqueous ammonia to the cooled solution in step (1) while stirring, adjusting the pH of the solution to about 9, and adding 5-10 mL of excess aqueous ammonia, and letting it stand for 1-2 hours; (3) Filter the solution after standing in step (2) using slow filter paper, wash the beaker and the precipitate with 1:19 nitric acid for 6-7 times respectively, retain the precipitate, discard the filtrate, put the filter paper and the precipitate into the original beaker, add nitric acid and sulfuric acid mixed acid with a volume ratio of 2:1 for treatment, prepare a 1:9 hydrochloric acid solution, determine the volume, and then convert it into chloride ion content by ICP. The amount of mercury and chloride ion in the aminomercuric chloride compound is 1:2; The chemical reagents used in the test method were all analytically pure reagents, 15 mol / L nitric acid and 15 mol / L ammonia water.

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