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CN-121974383-A - Preparation method of ultra-high-purity electronic grade silver nitrate

CN121974383ACN 121974383 ACN121974383 ACN 121974383ACN-121974383-A

Abstract

The invention discloses a preparation method of ultra-high-purity electronic grade silver nitrate, which relates to the technical fields of precious metal fine chemical industry and electronic material preparation, and realizes high-efficiency preparation through a full-flow optimization process of catalytic dissolution-gradient temperature control silver dissolution, a composite purification system cooperated with ceramic membrane filtration, gradient decompression-ultrasonic auxiliary crystallization, closed-loop waste gas treatment, low-temperature pulsation drying and multistage recovery and AI intelligent quality control. Under the optimization of key parameters, the silver nitrate content of the product reaches 99.996 percent, and the silver recovery rate is 99.970 percent. The method has the advantages of resource recycling, low energy consumption and stable quality, and can meet the severe requirements of the large-scale production of the electronic materials on the ultra-high purity silver nitrate.

Inventors

  • ZHANG HONGWANG
  • LIN SONG
  • SHI WEILI

Assignees

  • 江苏鸿脉新材料有限公司

Dates

Publication Date
20260505
Application Date
20260127

Claims (10)

  1. 1. The preparation method of the ultra-high-purity electronic grade silver nitrate is characterized by comprising the following steps of: Step S1, catalytic dissolution-gradient temperature control silver dissolution, namely mixing silver ingots with nitric acid, adding a composite catalytic auxiliary agent into a reaction system, adopting low-temperature start-medium-temperature reaction-high-temperature impurity removal three-stage gradient temperature control, controlling the dropping speed of nitric acid to be 120-130L/h by a DCS system linked tantalum dual-flow metering pump, and simultaneously introducing nitrogen with the purity of more than or equal to 99.99% as a shielding gas at the flow rate of 5-8L/min; Step S2, multistage collaborative purification, namely adding a composite purification system into the silver nitrate solution prepared in the step S1, stirring and reacting for 30-40min at 75-80 ℃ and 300-350r/min, and then filtering by adopting a ceramic membrane to remove sediment; step S3, negative pressure coupling crystallization, namely delivering the filtrate obtained in the step S2 into a negative pressure evaporation kettle, adopting a gradient decompression-constant temperature concentration process, transferring the concentrated filtrate into a crystallization kettle, and adopting program cooling and ultrasonic auxiliary crystallization; Step S4, closed-loop waste gas treatment, namely sequentially passing NO x waste gas generated in the step S1 through a condenser, a primary hydrogen peroxide washing tower, a secondary alkali absorption tower and an adsorption-desorption tower, wherein the desorption process adopts 120-150 ℃ hot air, the desorbed NO x and oxygen are mixed according to the volume ratio of 4:1, and the mixture is introduced into a catalytic converter to be converted into 65% concentration nitric acid at 300-350 ℃ for recycling to the silver dissolving process of the step S1; S5, low-temperature pulsation drying and multi-stage recovery, namely, sending the crystal obtained in the step S3 into a low-temperature vacuum pulsation dryer, controlling the vacuum degree to be less than or equal to 0.09MPa, controlling the drying temperature to be 80-90 ℃, and drying for 3-4 hours at the pulsation frequency of 30-50 times/min; And S6, AI intelligent quality control, namely monitoring the grain diameter and impurity content of the crystal in real time by a laser particle analyzer and an inductively coupled plasma mass spectrometer, and enabling an AI control system to adaptively adjust the crystallization temperature, ultrasonic parameters and drying pulsation frequency according to detection data so as to ensure the uniformity of the quality of the product.
  2. 2. The method for preparing ultra-high-purity electronic grade silver nitrate according to claim 1, wherein in the step S1, the silver ingot is national standard No. 1 silver ingot, the purity is 99.99%, and the mass percentage concentration of nitric acid is 65%.
  3. 3. The method for preparing ultra-high-purity electronic grade silver nitrate according to claim 1, wherein the mass ratio of the silver ingot to the nitric acid to the composite catalyst auxiliary agent in the step S1 is 100 (78-82) (0.001-0.003).
  4. 4. The preparation method of the ultra-high-purity electronic grade silver nitrate according to claim 1, wherein the composite catalyst auxiliary agent in the step S1 is formed by compounding cerium oxide and potassium fluoborate according to a mass ratio of 2:1.
  5. 5. The method for preparing ultra-high-purity electronic grade silver nitrate according to claim 1, wherein the three-stage gradient temperature control in the step S1 is specifically performed in a first stage for 30-60min at a temperature of 85-95 ℃, a second stage for 6-7h at a temperature of 100-110 ℃, and a third stage for 30-60min at a temperature of 115-120 ℃.
  6. 6. The method for preparing ultra-high-purity electronic grade silver nitrate according to claim 1, wherein the composite catalyst auxiliary agent in the step S1 is added in a manner of adding 30wt% before the dropwise addition of nitric acid, 50wt% in the middle of the reaction and 20wt% in the later of the reaction.
  7. 7. The preparation method of the ultra-high-purity electronic grade silver nitrate according to claim 1, wherein the composite purification system in the step S2 consists of a chelating main agent and a catalytic decomposition agent according to the mass ratio of 5 (2-3), wherein the chelating main agent is formed by compounding N-benzoyl-N-phenylhydroxylamine and diethyl sodium dithiocarbamate according to the mass ratio of 3:2, and the catalytic decomposition agent is nano titanium dioxide with the average particle size of 20-50 nm.
  8. 8. The method for preparing ultra-high-purity electronic grade silver nitrate according to claim 1, wherein the amount of the composite purification system in step S2 is 0.10-0.12kg/kg silver ingot, and the pore diameter of the ceramic membrane in step S2 is 50-100nm.
  9. 9. The method for preparing the ultra-high-purity electronic grade silver nitrate according to claim 1, wherein the gradient decompression-constant temperature concentration process in the step S3 is characterized in that the pressure of the first stage is 0.06-0.08MPa, the temperature is 120-130 ℃, the concentration is carried out until the specific gravity of a solution is 2.8-3.0g/cm 3 , the pressure of the second stage is 0.02-0.04MPa, the temperature is 130-140 ℃, the specific gravity is 3.2-3.3g/cm 3 , the program cooling and the ultrasonic auxiliary crystallization in the step S3 are specifically carried out by cooling to 30 ℃ at a speed of 1 ℃ per minute, preserving heat for 1h, cooling to 15-20 ℃ at a speed of 0.5 ℃ per minute, and simultaneously applying 20-30kHz ultrasonic, and the ultrasonic power is 50-80W for 30min.
  10. 10. The preparation method of the ultra-high-purity electronic grade silver nitrate according to claim 1, wherein the hydrogen peroxide in the step S4 is 5-8% in percentage by mass, the alkali is 10-15% sodium hydroxide solution in percentage by mass, and the catalyst in the catalytic converter is platinum-rhodium alloy.

Description

Preparation method of ultra-high-purity electronic grade silver nitrate Technical Field The invention relates to the technical field of precious metal fine chemical engineering and electronic material preparation, in particular to a preparation method of ultra-high-purity electronic grade silver nitrate. Background Silver nitrate is used as a core base material in the electronic information industry, and its purity directly determines the performance of downstream electronic materials. Along with the advancement of semiconductor technology to processes of 5nm and below, the conversion efficiency of photovoltaic cells is continuously improved, the purity requirement on silver nitrate is improved from 'high-grade purity' to 'electronic-grade ultra-high purity', and meanwhile, good crystal dispersibility and no agglomeration phenomenon are required to be ensured. At present, the main stream of silver nitrate production adopts an acidolysis method, and the core flow comprises the steps of silver dissolution, purification, evaporative crystallization, drying and the like. The existing process has the defects that the quality of raw materials is not guaranteed, effective impurity removal means are lacked, impurities such as iron, copper and lead are not thoroughly removed, the product purity is difficult to meet the electronic-grade application requirements, the reaction is coarsely controlled, the nitric acid addition mode is unreasonable, the reaction is severe, the temperature fluctuation is large (more than +/-5 ℃), NO x waste gas is largely generated, the treatment efficiency is low, the environment-friendly standard pressure is high, the solid-liquid separation adopts a traditional centrifuge, silver nitrate crystals are easy to damage, the manual operation intensity is high, the drying adopts a decompression drying mode, the energy consumption is high, the efficiency is low, the production period is long, the equipment material selection is improper, the common metal flowmeter is easy to be corroded by nitric acid, the feeding precision is influenced, the whole-flow automatic control is lacked, the safety risk is high, the equipment investment cost is high, and the requirements of domestic raw material supply and environmental protection policies are not met. In order to solve the technical problems, the invention patent document CN103214022B discloses a preparation method of high-purity silver nitrate, which comprises the steps of cleaning the surface of metal silver with dilute nitric acid, adding pure water, slowly adding nitric acid, controlling the reaction temperature to 80-90 ℃, after the reaction is completed, removing redundant nitric acid through thermal boiling, adding pure water to adjust the specific gravity of the solution to 1.80-1.90g/ml, standing, filtering, hydrolyzing and coprecipitating, namely heating filtrate to 90+/-5 ℃, adding a impurity removing agent under stirring, adding silver oxide to adjust the pH value of the solution to be=6.5+/-0.3, stopping heating after stirring, standing for precipitation, filtering, adjusting the pH value of the filtrate to be=1-3 with dilute nitric acid, concentrating, crystallizing, filtering and drying to obtain a finished product. The content of impurity metal ions in the silver nitrate prepared by the method is below 10 ppb. However, the method has the problems that the reaction temperature regulation lacks a precise interlocking mechanism, NO x waste gas does not form a closed-loop recovery system, hydrolysis coprecipitation and pH regulation step-by-step operation lead to lower process efficiency, and anion impurities such as chloride, sulfate and the like are not removed specially, so that the severe requirements of the high-end electronics field on the purity of silver nitrate and the production economy are difficult to meet. Therefore, the development of the preparation method of the ultra-high-purity electronic grade silver nitrate with stable process, high efficiency in impurity removal, environmental protection and safety and short production period becomes a problem to be solved urgently in the industry. Disclosure of Invention The invention aims to overcome the defects of the prior art and provide the preparation method of the ultra-high-purity electronic grade silver nitrate, which has the advantages of stable process, high impurity removal efficiency, environmental protection, safety and short production period. In order to achieve the aim, the technical scheme adopted by the invention is that the preparation method of the ultra-high-purity electronic grade silver nitrate comprises the following steps of: Step S1, catalytic dissolution-gradient temperature control silver dissolution, namely mixing silver ingots with nitric acid, adding a composite catalytic auxiliary agent into a reaction system, adopting low-temperature start-medium-temperature reaction-high-temperature impurity removal three-stage gradient temperature control, contro