CN102040240A - Method for producing high-purity silver nitrate - Google Patents

Abstract

The invention discloses a method for producing high-purity silver nitrate, comprising the following steps of: (1) reacting: flushing silver with purified water, placing the flushed silver in a reaction kettle, adding pure nitric acid, keeping the silver to be excessive, heating to 70DEG C, removing excessive nitrides and adjusting the pH value of a reaction solution; (2) hydrolyzing: adding the reaction solution in a hydrolysis kettle, flushing and diluting until the density is 1.6-1.7g/cm<3>, adding an impurity removing agent, standing for 10-16 hours and filtering to obtain filtrate; (3) evaporating and crystallizing: carrying out the pressure reduction and evaporation on the filtrate subjected to the impurity removal and cooling and crystallizing when the specific gravity is 3.2g/cm<3>; and (4) centrifuging and drying: after centrifuging and separating a crystal which is crystallized and separated out, allowing a solid to enter vacuum drying equipment, heating, decompressing and drying for 24 hours to obtain a pure silver nitrate finished product. The silver nitrate produced by the method has low metal content and high quality.

Description

A kind of method of producing high purity silver nitrate

Technical field

The present invention relates to a kind of production method of Silver Nitrate, especially a kind of production method of high-purity silver nitrate.

Background technology

Sensitization industry is the comprehensive great fine chemistry industry of a multidisciplinary multiple-project, for sensitive materials, prepares the purity of the required raw material of this material, is confirmed by the history of the sensitization industrial development of many countries in the world.The needed main raw material of preparation sensitive emulsion---Silver Nitrate.But for many years,, there are all detrimental impurity in the Silver Nitrate, bring difficulty for the high-grade negativity film of production because quality does not pass a test, the unity of product and poor stability, the later stage performance is often prematurely senile, becomes substandard products.

No matter the quality present situation of Silver Nitrate product is a photographic-grade, still there is top grade pure, all exist the checked for impurities element few, the shortcoming of foreign matter content height (reaching 1-5ppm).The tradition synthesis method is with the silver ingot deionized water rinsing, remove surface contaminants after, add in the reactor that the strap clamp cover heats, add distilled water earlier, add concentrated nitric acid again, make concentration of nitric acid be about 60～65%. control temperature of reaction kettle, make reaction unlikely acute excessively, and nitrogen oxide is overflowed.It is 1.6～1.7g/cm3 that reaction solution is diluted to relative density with deionized water, cooling was left standstill 10-16 hour, the filtering Sulfuric acid disilver salt, throw out and suspended substances such as bismuth sulfate, clear liquid be through reduction vaporization, treats that solution concentration is when crystalline film appears in the surface, deliver to crystallization kettle, leave standstill, the crystallisation by cooling centrifugation, 90 ℃ down dry, make the Silver Nitrate finished product.There is following inherent defect in this flow process:

A, lack necessary effectively impurity elimination means, the impurity of Silver Nitrate product is many.

B, production unit poor-performing might cause foreign matter to enter in the Silver Nitrate product.

Summary of the invention

Purpose of the present invention is exactly to solve the not high problem of product purity that existing Silver Nitrate production method is produced, and a kind of production method of highly purified Silver Nitrate is provided.

The technical solution used in the present invention is: a kind of method of producing high purity silver nitrate is characterized in that it may further comprise the steps:

(1) reaction: get the silver pure water rinsing, remove surface contaminants, place reactor again, add the pure nitric acid after distillation in batches, keep silver excessive in the reaction process, be heated to 70 ℃, catch up with under the negative pressure condition and remove unnecessary nitride, conditioned reaction liquid pH value is to PH3～4;

(2) hydrolysis: above-mentioned reaction solution is added hydrolysis kettle, with pure water towards rare to density be 1.6-1.7g/cm3, add cleaner magnesium oxide, slowly stir, cooling was left standstill 10-16 hour again, removed by filter impurity, filtrate;

(3) evaporative crystallization: the filtrate after the removal of impurity is sent into the evaporative crystallization still, and reduction vaporization slowly stirs, when proportion was 3.2g/cm3, crystallisation by cooling was during crystallization, be ten minutes by 1 ℃ strong cold process of the strong cold per minute cooling of recirculated water earlier, cooling in per ten minutes was slowly cooled off 3 hours for 1 ℃ then;

(4) centrifugal drying: after the crystal centrifugation was separated out in crystallization, solid entered vacuum dryer, and heating drying under reduced pressure 24 hours gets the high purity silver nitrate finished product.

Adopt technique scheme owing to adopt cleaner in the production technique of the present invention, make metallic impurity especially precipitation by metallic ion get off, reach the purpose of removal of impurities again by solid-liquid separation, so the content of the metallic impurity of product is low.

For stoping the influence of reaction vessel metallic corrosion to the Silver Nitrate quality product, described reactor, hydrolysis kettle, crystallization kettle material are the stainless steel lined titanium.Above-mentioned materials is basic not corrosion in Silver Nitrate and nitric acid, and is therefore minimum to the quality product influence.

In sum, the invention has the beneficial effects as follows:, therefore make the quality product of the Silver Nitrate of producing obtain improving greatly because the present invention is provided with the removal of impurities operation; Because the present invention adopts the stainless steel lined titanium metal material, so the metal content in the Silver Nitrate product is little, the quality height of Silver Nitrate product.

Test products foreign matter content result is as shown in table 1 through Beijing Physichemistry Analysis ﹠ Measurment Centre.

Table 1: Beijing Physichemistry Analysis ﹠ Measurment Centre's test result (ppm)

Twice test result all meets or exceeds the countries concerned's standard of Silver Nitrate product

Embodiment

A kind of method of producing high purity silver nitrate of the present invention, it may further comprise the steps:

(1) reaction: get the silver pure water rinsing, remove surface contaminants, place reactor again, add the pure nitric acid after distillation in batches, keep silver excessive in the reaction process, be heated to 70 ℃, catch up with under the negative pressure condition and remove unnecessary nitride, conditioned reaction liquid pH value is to PH3.5;

(2) hydrolysis: above-mentioned reaction solution is added hydrolysis kettle, with pure water towards rare to density be 1.65g/cm3, add cleaner magnesium oxide, slowly stir, cooling was left standstill 13 hours again, removed by filter impurity, filtrate;

(3) evaporative crystallization: the filtrate after the removal of impurity is sent into the evaporative crystallization still, and reduction vaporization slowly stirs, when proportion was 3.2g/cm3, crystallisation by cooling was during crystallization, be ten minutes by 1 ℃ strong cold process of the strong cold per minute cooling of recirculated water earlier, cooling in per ten minutes was slowly cooled off 3 hours for 1 ℃ then;

(4) centrifugal drying: after the crystal centrifugation was separated out in crystallization, solid entered vacuum dryer, and heating drying under reduced pressure 24 hours gets the high purity silver nitrate finished product.

Reactor, hydrolysis kettle, crystallization kettle material are the stainless steel lined titanium.

Claims (2)

1. method of producing high purity silver nitrate is characterized in that it may further comprise the steps:

(1) reaction: get the silver pure water rinsing, remove surface contaminants, place reactor again, add the pure nitric acid after distillation in batches, keep silver excessive in the reaction process, be heated to 70 ℃, catch up with under the negative pressure condition and remove unnecessary nitride, conditioned reaction liquid pH value is to PH3～4;

(2) hydrolysis: above-mentioned reaction solution is added hydrolysis kettle, with pure water towards rare to density be 1.6-1.7g/cm3, add cleaner magnesium oxide, slowly stir, cooling was left standstill 10-16 hour again, removed by filter impurity, filtrate;

(3) evaporative crystallization: the filtrate after the removal of impurity is sent into the evaporative crystallization still, and reduction vaporization slowly stirs, when proportion was 3.2g/cm3, crystallisation by cooling was during crystallization, be ten minutes by 1 ℃ strong cold process of the strong cold per minute cooling of recirculated water earlier, cooling in per ten minutes was slowly cooled off 3 hours for 1 ℃ then;

(4) centrifugal drying: after the crystal centrifugation was separated out in crystallization, solid entered vacuum dryer, and heating drying under reduced pressure 24 hours gets the high purity silver nitrate finished product.

2. the production method of high purity silver nitrate according to claim 1 is characterized in that described reactor, hydrolysis kettle, crystallization kettle material are the stainless steel lined titanium.