Method for removing silver from silver-containing noble metal material through nitric acid
By controlling the potential of the nitric acid solution within 800 ± 20mv range, the problem of long and deep separation of the split process of the silver cymbals in existing technologies has been solved, and efficient silver depth removal and low -cost production have been achieved.
Patent Information
- Application Number
- CN202411379240.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-30
- Publication Date
- 2025-01-24
AI Technical Summary
In the prior art, the process of silver palladium separation is lengthy and difficult to separate in depth, resulting in a low direct yield of palladium and a high separation process cost.
By controlling the concentration of nitric acid in the reaction solution, the potential of the solution is controlled near 800 ± 20mV to ensure that the precious metal tadpoles are not dissolved and the depth of silver is removed.
The depth removal of silver is achieved, the leaching rate of the silver is greater than 95 %, and the immersion rate of other precious metals is less than 0.3 %. At the same time, the volatilization of nitrogen oxides and the loss of nitric acid are reduced to the maximum extent, and production costs are reduced.
Smart Images
Figure BDA0005069477540000041 
Figure BDA0005069477540000051 
Figure BDA0005069477540000061
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of noble metal hydrometallurgy, and in particular to a method for removing silver from silver-containing noble metal materials by nitric acid. Background Art
[0002] In precious metal materials and concentrates, especially palladium concentrates, there is often a large amount of silver, which is not conducive to the purification of other precious metals. In industry, a variety of methods for separating silver and palladium have been explored, including reduction smelting, solvent extraction, ion exchange, complexation, and acid-base leaching, but these methods all have certain limitations. In the process of separating silver and palladium by reduction smelting, palladium will volatilize and lose, resulting in a low direct recovery rate of palladium; although solvent extraction and ion exchange methods can achieve deep separation of silver and palladium, the palladium concentrate must be dissolved before separation and enrichment, the process is long and there are many restrictions on the impurity components of palladium concentrate; the complexation method usually uses ammonia water, thiourea, oxalic acid and other complexing agents for silver and palladium separation, and the direct recovery rate of palladium is low and the scope of application is small. At present, most factories usually use acid leaching to separate silver and palladium, and then purify them separately. Because the leaching potentials of silver and palladium are close, it is difficult to separate silver and palladium deeply during leaching, and the separation process is lengthy. Therefore, it is of great significance to develop and design a method with a short process flow and deep silver removal. Summary of the invention
[0003] In view of the problems of lengthy silver-palladium separation process and difficult deep separation in the above-mentioned prior art, the present invention provides a method for desilvering silver-containing precious metal materials by nitric acid. By controlling the concentration of nitric acid in the reaction solution, the solution potential is controlled at around 800±20mV to ensure that the precious metal palladium is not dissolved, thereby achieving deep removal of silver.
[0004] To achieve the above object, the technical solution of the present invention is as follows:
[0005] A method for desilvering a silver-containing precious metal material by nitric acid, comprising the following steps:
[0006] (1) taking equal volumes of concentrated nitric acid and pure water, and mixing 1 / 3-1 / 2 volume of the concentrated nitric acid and the pure water evenly to obtain a base solution;
[0007] (2) weighing a silver-containing precious metal material in a ratio of base liquid to silver-containing precious metal material = 8-10:1, starting stirring, adding the silver-containing precious metal material to the base liquid at room temperature, and simultaneously adding the remaining concentrated nitric acid in step (1) in a titrating manner;
[0008] (3) After the addition of the silver-containing precious metal material is completed, the solution temperature is maintained at 25-45° C., and the reaction is continued for 0.5-1 h after the remaining concentrated nitric acid in step (1) is completely titrated;
[0009] (4) filtering the mixture after the reaction, and obtaining a filtrate as a silver-containing leaching solution, and obtaining a filter residue as a desilvered precious metal concentrate after washing.
[0010] Furthermore, in the process of adding the silver-containing precious metal material in step (2), the solution temperature does not exceed 45°C.
[0011] Furthermore, in the process of adding the concentrated nitric acid in the step (2), the solution potential is not greater than 900 mV.
[0012] Furthermore, during the process of adding the concentrated nitric acid in step (2), the solution potential is 800±20 mV.
[0013] Furthermore, the leaching rate of silver in the obtained filtrate is greater than 95%, and the leaching rate of other precious metals is less than 0.3%.
[0014] Furthermore, the silver-containing precious metal material includes palladium.
[0015] Compared with the prior art, the present invention has the following beneficial effects:
[0016] The invention provides a method for nitric acid desilvering of silver-containing precious metal materials. The method has a short process flow, simple operation and low cost. By adjusting the nitric acid concentration and reaction temperature in the reaction solution, the solution potential value is accurately controlled at 800±20mV, and the leaching of other precious metals is greatly reduced while leaching silver, thereby achieving deep desilvering of silver-containing precious metal materials. In the method, the leaching rate of silver is greater than 95%, and the leaching rate of other precious metals is less than 0.3%. In addition, the method minimizes the volatilization of nitrogen oxides, reduces the loss of nitric acid, and thus reduces the production cost. DETAILED DESCRIPTION
[0017] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail by specific embodiments below. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.
[0018] A method for desilvering a silver-containing precious metal material by nitric acid, comprising the following steps:
[0019] (1) taking equal volumes of concentrated nitric acid and pure water, and mixing 1 / 3-1 / 2 volume of the concentrated nitric acid and the pure water evenly to obtain a base solution;
[0020] (2) weighing the silver-containing precious metal material in a ratio of base liquid to silver-containing precious metal material = 8-10:1, starting stirring, adding the silver-containing precious metal material to the base liquid at room temperature, and keeping the solution temperature below 45° C. during the addition of the silver-containing precious metal material; at the same time, adding the remaining concentrated nitric acid in step (1) in a titration manner, and keeping the solution potential below 900 mV during the addition of concentrated nitric acid to prevent the precious metal palladium from being leached;
[0021] (3) After the addition of the silver-containing precious metal material is completed, the solution temperature is maintained at 25-45° C., and the reaction is continued for 0.5-1 h after the remaining concentrated nitric acid in step (1) is completely titrated;
[0022] (4) filtering the mixture after the reaction, and obtaining a filtrate as a silver-containing leaching solution, and obtaining a filter residue as a desilvered precious metal concentrate after washing.
[0023] In one embodiment of the present invention, the solution potential during the process of adding concentrated nitric acid in step (2) is 800±20 mV.
[0024] Example 1
[0025] The contents of various metals in the silver-containing precious metal material were tested, and the test results are shown in Table 1.
[0026] Table 1 Content of various metals in silver-containing precious metal materials (g / t)
[0027] Metal Type Ni Cu Fe Ag Au Pd Pt content 60.28 5.11 3.79 32840 386 5835 1965
[0028] Take equal volumes of concentrated nitric acid and pure water, mix 1 / 2 volume of concentrated nitric acid and pure water evenly to obtain a base liquid; weigh the silver-containing precious metal material according to the ratio of base liquid: silver-containing precious metal material = 10:1, start stirring, add the silver-containing precious metal material to the base liquid at room temperature, and keep the solution temperature at 35°C during the addition of the silver-containing precious metal material; at the same time, add the remaining concentrated nitric acid in a titration manner, and keep the solution potential at 900mV during the addition of concentrated nitric acid; after the addition of the silver-containing precious metal material is completed, keep the solution temperature at 25°C, and react for 1h after the remaining concentrated nitric acid is completely titrated, filter the reaction mixture, and test the content of various metals in the filtrate. The test results are shown in Table 2.
[0029] Table 2 Content of various metals in the filtrate after silver removal from silver-containing precious metal materials (mg / L)
[0030] Metal Type Ni Cu Fe Ag Au Pd Pt content 50.1 4.14 2.7 2780 0.05 0.13 0.02
[0031] The liquid-based leaching rate and slag-based leaching rate of various metal elements were calculated according to the formula, and the results are shown in Table 3.
[0032]
[0033] Table 3 Leaching rate of various metals (%)
[0034] Metal Type Ni Cu Fe Ag Au Pd Pt Leaching rate 95.08 92.68 81.50 96.84 0.15 0.03 0.01
[0035] Example 2
[0036] The contents of various metals in the silver-containing precious metal material were tested, and the test results are shown in Table 4.
[0037] Table 4 Content of various metals in silver-containing precious metal materials (g / t)
[0038] Metal Type Ni Cu Fe Ag Au Pd Pt content 13.88 1.24 6.5 78998 1159 23400 6124
[0039] Take equal volumes of concentrated nitric acid and pure water, mix 1 / 3 volume of concentrated nitric acid and pure water evenly to obtain a base liquid; weigh the silver-containing precious metal material according to the ratio of base liquid: silver-containing precious metal material = 8:1, start stirring, add the silver-containing precious metal material to the base liquid at room temperature, and keep the solution temperature at 45°C during the addition of the silver-containing precious metal material; at the same time, add the remaining concentrated nitric acid in a titration manner, and keep the solution potential at 780mV during the dropwise addition of concentrated nitric acid; after the addition of the silver-containing precious metal material is completed, keep the solution temperature at 45°C, and react for 0.5h after the remaining concentrated nitric acid is completely titrated, filter the mixture after the reaction, and test the content of various metals in the filtrate. The test results are shown in Table 5.
[0040] Table 5 Content of various metals in the filtrate after desilvering of silver-containing precious metal materials (mg / L)
[0041] Metal Type Ni Cu Fe Ag Au Pd Pt content 11.10 0.92 9.52 6180 0.01 0.86 0.25
[0042] The liquid-based leaching rate and slag-based leaching rate of various metal elements were calculated according to the formula, and the results are shown in Table 6.
[0043]
[0044] Table 6 Leaching rate of various metals (%)
[0045] Metal Type Ni Cu Fe Ag Au Pd Pt Leaching rate 97.88 90.87 70.64 95.75 0.01 0.04 0.05
[0046] Example 3
[0047] The contents of various metals in the silver-containing precious metal material were tested, and the test results are shown in Table 7.
[0048] Table 7 Content of various metals in silver-containing precious metal materials (g / t)
[0049] Metal Type Ni Cu Fe Ag Au Pd Pt content 22.03 43.52 3.95 8457 1243 2511 967
[0050] Take equal volumes of concentrated nitric acid and pure water, mix 1 / 2 volume of concentrated nitric acid and pure water evenly to obtain a base liquid; weigh the silver-containing precious metal material according to the ratio of base liquid: silver-containing precious metal material = 9:1, start stirring, add the silver-containing precious metal material to the base liquid at room temperature, and keep the solution temperature at 30°C during the addition of the silver-containing precious metal material; at the same time, add the remaining concentrated nitric acid in a titration manner, and keep the solution potential at 820mV during the addition of concentrated nitric acid; after the addition of the silver-containing precious metal material is completed, keep the solution temperature at 35°C, and react for 0.75h after the remaining concentrated nitric acid is completely titrated, filter the reaction mixture, and test the content of various metals in the filtrate. The test results are shown in Table 8.
[0051] Table 8 Content of various metals in the filtrate after desilvering of silver-containing precious metal materials (mg / L)
[0052] Metal Type Ni Cu Fe Ag Au Pd Pt content 28.76 48.35 5.08 1085 0.05 0.03 0.04
[0053] The liquid-based leaching rate and slag-based leaching rate of various metal elements were calculated according to the formula, and the results are shown in Table 9.
[0054]
[0055] Table 9 Leaching rate of various metals (%)
[0056] Metal Type Ni Cu Fe Ag Au Pd Pt Leaching rate 98.35 83.69 96.88 96.64 0.03 0.01 0.03
[0057] The invention provides a method for nitric acid desilvering of silver-containing precious metal materials. The method has a short process flow, simple operation and low cost. By adjusting the nitric acid concentration and reaction temperature in the reaction solution, the solution potential value is accurately controlled at 800±20mV, and the leaching of other precious metals is greatly reduced while leaching silver, thereby achieving deep desilvering of silver-containing precious metal materials. In the method, the leaching rate of silver is greater than 95%, and the leaching rate of other precious metals is less than 0.3%. In addition, the method minimizes the volatilization of nitrogen oxides, reduces the loss of nitric acid, and thus reduces the production cost.
[0058] Some exemplary embodiments of the present invention are described above. It can be understood that the above embodiments are only used to explain the present invention and do not constitute a limitation on the protection scope of the present invention. The features in these embodiments can be recombined in a suitable manner, and the scheme obtained thereby is still within the protection scope required by the present invention. Based on the above embodiments, all other embodiments obtained by those skilled in the art without making creative work, that is, all modifications, equivalent substitutions and improvements made within the spirit and principles of this application, fall within the protection scope required by the present invention.
Claims
1. A method for desilvering a silver-containing precious metal material by nitric acid, characterized in that: The following steps are involved: (1) taking equal volumes of concentrated nitric acid and pure water, and mixing 1 / 3-1 / 2 volume of the concentrated nitric acid and the pure water evenly to obtain a base solution; (2) weighing a silver-containing precious metal material in a ratio of base liquid to silver-containing precious metal material = 8-10:1, starting stirring, adding the silver-containing precious metal material to the base liquid at room temperature, and simultaneously adding the remaining concentrated nitric acid in step (1) in a titrating manner; (3) After the addition of the silver-containing precious metal material is completed, the solution temperature is maintained at 25-45° C., and the reaction is continued for 0.5-1 h after the remaining concentrated nitric acid in step (1) is completely titrated; (4) filtering the mixture after the reaction, and obtaining a filtrate as a silver-containing leaching solution, and obtaining a filter residue as a desilvered precious metal concentrate after washing.
2. The method for desilvering a silver-containing precious metal material by nitric acid according to claim 1, characterized in that: During the process of adding the silver-containing precious metal material in step (2), the solution temperature does not exceed 45°C.
3. The method for desilvering a silver-containing precious metal material by nitric acid according to claim 1, characterized in that: During the process of adding the concentrated nitric acid in the step (2), the solution potential is not greater than 900 mV.
4. The method for desilvering a silver-containing precious metal material by nitric acid according to claim 1 or 3, characterized in that: During the process of adding the concentrated nitric acid in step (2), the solution potential is 800±20 mV.
5. The method for desilvering a silver-containing precious metal material by nitric acid according to claim 1, characterized in that: The leaching rate of silver in the obtained filtrate is greater than 95%, and the leaching rate of other precious metals is less than 0.3%.
6. The method for desilvering a silver-containing precious metal material by nitric acid according to claim 1, characterized in that: The silver-containing precious metal material includes palladium.