JPS582209A - Manufacture of metallic nitrate - Google Patents

Abstract

PURPOSE:To efficiently manufacture a high purity aqueous soln. of a metallic nitrate without generating gaseous nitrogen oxide by reacting a metal with nitric acid in the presence of hydrogen peroxide. CONSTITUTION:When a metallic nitrate is manufactured by a reacting a metal such as Ag, Cu or Bi with nitric acid, during, before or after adding nitric acid, hydrogen peroxide is added continuously or in several times. Nitrogen oxide generated during the progress of the reaction is converted into nitric acid radicals at once by oxidation with adjacent hydrogen peroxide, facilitating the dissolution of the metal. By this method an aqueous soln. of a metallic nitrate is efficiently obtd. in one stage without practically generating gaseous nitrogen oxide. Since the soln. contains no impurities, high purity metallic nitrate crystals can be obtd. from the soln.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in the process for producing metal nitrates by reaction of metals with nitric acid.

Metal nitrates are used in a wide range of fields in the chemical industry, depending on the metal, such as medicines, catalysts, analytical reagents, pigments, raw materials for the plating industry, and raw materials for metal compounds.

Traditionally, metal nitrates are produced by dissolving metals, metal oxides, metal hydroxides, metal carbonates, etc. in dilute nitric acid to create a nitric acidic metal nitrate aqueous solution, and then neutralizing with an alkali. A method of evaporating and concentrating the sum or t9 as it is to form crystals is carried out. Among these methods, the method of dissolving metals with nitric acid is used when the metal is relatively easily obtained in a state with a large surface area, such as in the form of granules or pieces, or when the metal nitrate has a mourning band of high purity 11. It is adopted as such.

However, when producing nitrates of silver, bismuth, copper, mercury, cobalt, nickel, lead, etc. from warehouses,
During the reaction between these O metals and nitric acid, there is no harmful gas of nitrogen oxides.
** can be avoided. The generation of this gas becomes more intense as the nitric acid, addition rate, and treatment temperature are increased to accelerate the dissolution rate. Therefore, there is a problem that denitrification treatment equipment is indispensable on an industrial scale.

The present invention solves the above-mentioned problems and produces highly pure metal nitrate water in one step without substantially generating nitrogen oxide gas during the decomposition of these metals with nitric acid. The purpose is to efficiently produce St.

According to the present invention, in the production of metal nitrates in which nitric acid is reacted with metals, the reaction with nitric acid as described above is accompanied by the generation of nitrogen oxides, and the cough reaction is carried out in the presence of hydrogen peroxide. It is characterized by

It is not clear why nitrogen oxide gas is no longer generated when a metal is reacted with nitric acid in the presence of hydrogen peroxide.

It is also thought that the encounter in the estimated range is once generated by the reaction between the metal and nitric acid, and the nitrogen oxides are immediately oxidized by hydrogen peroxide in the vicinity of K, making it easier to elute the extracted metal as nitrate radicals. Generally, the reaction between a metal and nitric acid is carried out by adding nitric acid to the metal in many divided portions or by continuously adding the nitric acid to the metal and causing the reaction to occur sequentially. Although it varies depending on the type, shape, and surface condition of the metal, metals usually do not react with K immediately, but react relatively rapidly after a certain period of time when the nitric acid concentration and surface condition reach an appropriate level. (the liquid temperature rises), and thereafter the dissolution progresses steadily. In order to completely oxidize the nitrogen oxides generated during the progress of such a reaction according to the above-mentioned idea, it is necessary to have enough hydrogen peroxide present to convert them into nitrate radicals. At the beginning of the reaction between the metal and nitric acid, as mentioned above, due to various conditions, especially the liquid temperature is not constant during the reaction rate, hydrogen peroxide may be added to the reaction liquid at the same time or before or after the addition of nitric acid, as appropriate. Just let it happen. After the initial stage of the reaction, nitric acid and hydrogen peroxide can be added simultaneously as a mixed solution or separately in a continuous K.
Alternatively, it may be added in multiple parts. The nitric acid and hydrogen peroxide used may be either concentrated or diluted. In addition, 1 is used for rounding to efficiently proceed with such reactions.
It goes without saying that stirring is required to make the reaction (product) homogeneous and that the amount of solution is sufficient to convert all of the metal into nitrate.

Next, a more specific explanation will be given by illustrating silver, copper and bismuth as metals. To achieve the object of the present invention, which is to obtain a metal nitrate aqueous solution without generating nitrogen oxide gas by adding nitric acid and hydrogen peroxide to metal, K is the relative amount of nitric acid added at the same time as the amount of hydrogen peroxide used. I need to explain the ratio. At this time, it is assumed that the following reaction formula holds true for the reaction of silver, copper, or bismuth with nitric acid and hydrogen peroxide, for example.

2), y + 2HNO, + bird O3 → 2mu, No,
+ 2H, OCu + 2 HNO, + H, O, →
Cu(No,), +21! ! 02 Bi + 6H
N01+3HIO,-+Bi(NO,1,+sh.

That is, first, when the metal is silver, the number of moles of hydrogen peroxide used is stoichiometrically 0.5 times the number of moles of silver. However, in reality, it is desirable that it be 0.7 times or more. In addition, the quantitative relationship between hydrogen peroxide and nitric acid, which are added simultaneously, is that from the above reaction formula, the molar ratio of hydrogen peroxide to nitric acid is stoichiometrically 0.5, but in reality it is 0.37. It is necessary to add it in the above molar ratio. It is a matter of course that the nitric acid used in the reaction is present in an amount necessary for the silver dissolution reaction to proceed. The total molar ratio of the added amounts of nitric acid and/or hydrogen peroxide corresponding to such molar ratio must always be within the above range during addition. When dissolving scissors under the above conditions, the average dissolution rate is 1
The amount of gold and silver per hour is about 15 to 20 weight times, and the temperature of the liquid during the reaction rises to about 40°C.

Next, when one metal is copper, the molar multiple of hydrogen peroxide to copper needs to be at least 11 times, and the molar ratio of nitric acid to hydrogen peroxide needs to be at least 0.33 based on the same consideration as in the case of silver. . Under these conditions, copper is on average 10% of the total amount of steel (per hour)
1111 is dissolved in -24 weight, and the liquid temperature rise stops at around 6G'C. Furthermore, when one metal is bismuth, the molar ratio of hydrogen peroxide to bismuth must be 1.6 or more, and the molar ratio of hydrogen peroxide to nitrate must be 0.33 or more. Under these conditions, bismuth is dissolved in an average amount of about 50% of the total bismuth amount OIs per hour, but the liquid temperature is around SO°C.

These quantitative relationships for other metals that generate nitrogen oxide gas upon reaction with nitric acid can be appropriately selected based on the above criteria.

Examples will be described below.

Example 1 A piece of steel plate (20 square, l thick) Sof in a glass container with a lid
Collect it, add 100% water to it, and add 62X without stirring.
(Weight) Concentrated nitric acid (hereinafter referred to as nitric acid) 2o- and 3! To I was added (by weight) 10-hydrogen peroxide solution (hereinafter referred to as hydrogen peroxide). Thereafter, nitric acid and peroxide water were simultaneously pumped continuously at a volume of 0.63 m/h using separate metering pumps.
It was added for 4 hours at a ratio of sk and ozews/-. During the test, no nitrogen oxide gas was detected (the concentration analyzer showed zero), and the copper plate sample was completely dissolved in 5 hours. Note that the gas generated is introduced into the above reaction vessel.
Dilute and discharge with t/- air, and then o, s t7
- was diluted with 10t/- of air, the sample was collected as an analytical gas, analyzed with a nitrogen oxide analyzer, and continuously and automatically recorded. The liquid temperature was also continuously recorded automatically, and as a result, the liquid temperature was 20°C when the continuous addition of nitric acid and hydrogen peroxide started, but it gradually rose after that and reached a maximum of 54°C after 1 hour ls had passed. reached. Thereafter, after 2 hours and 48 minutes, the temperature reached a maximum of 48°C, and then gradually decreased.

Example 2 100F of silver powder was collected in a glass container with a lid, and 1 part of water was added to it.
00- was added thereto, and hydrogen peroxide solution 5- was further added while stirring. Thereafter, nitric acid and hydrogen peroxide were added simultaneously at 0.39 ml/- each continuously using separate metering pumps.
and O* a-/- for 6 hours. During the test, no nitrogen oxide gas was detected as the concentration analyzer showed zero, and the sample steel powder was completely dissolved in 6.5 hours. The analysis of the generated gas and the measurement of the liquid temperature were continuously and automatically recorded as in Example 1, but the liquid temperature was 19°C when the continuous addition of nitric acid and hydrogen peroxide started, and then gradually increased. After 2 hours, it reached the highest temperature of 31℃.

After that, it gradually declined.

Example 3 Collect granular bismuth 100f in a glass container with a lid,
Add 10 - of water to this and add 50 - of nitric acid while stirring.
Add 20- of hydrogen peroxide and form a circle.

Thereafter, nitric acid and hydrogen peroxide were simultaneously added continuously by separate metering pumps to 042 d/- and 0,21 ml, respectively.
/m () for 4 hours. During the test, no nitrogen oxide gas was generated as the concentration analyzer showed zero, and the sample bismuth grains were completely dissolved in 5 hours. The analysis of the generated gas and the measurement of the liquid temperature were continuously and automatically recorded in the same way as in Example 1.The liquid temperature was 22°C when the continuous addition of nitric acid and hydrogen peroxide started, and after that, the temperature rose relatively rapidly. The temperature rose to a maximum of 68°C 5 minutes later, but then decreased to 48.5°C after 1 hour, and then remained almost flat or slightly decreased.

Comparative Example 1 Hydrogen peroxide was not used, and nitric acid was continuously used at o, s.
Added for S time at a ratio of o d/-, all except 9 <Example 1
In the same manner as above, melt the copper plate piece and make a circle. After 1 hour and 10 minutes had passed after the start of continuous addition of nitric acid (liquid temperature 23°C), nitrogen oxide gas was observed to be generated.
,0OOppHm was recorded.9.

After that, gas generation of 13,500 to 16.5009 pm@degrees was observed, and after the addition of nitric acid was stopped, the rate rapidly decreased. The liquid temperature also showed roughly the same behavior as the above-mentioned change in the amount of gas generated, and after 1 hour and 45 minutes, Itsukushima 47
℃, but after that it gradually decreased. The test piece of copper plate was completely dissolved in 6 hours.

Comparative Example 2 Nitric acid and hydrogen peroxide were simultaneously added continuously using a separate fixed pump at a rate of 0.0, s4-/- for 4 hours.
The steel plate pieces were melted in the same manner as in Example 1 except for 9. Two hours after the start of continuous addition of nitric acid and hydrogen peroxide, the generation of nitrogen oxide gas started to be detected, and for the next two hours, the number of nitrogen oxide gas was several 1100p.
The situation continued with the occurrence of p@ change, but after that the generation of gas increased and the temperature was recorded at 28401) pm for 4 hours and 20 minutes, so an additional 10% of hydrogen peroxide was added (no further addition was made). .

Then, the gas production decreased rapidly until 9. When the liquid temperature was added, maximum values were shown at 4@, 8°C, and @LO°C, respectively. The copper urethane sample was completely dissolved in S time.

Comparative Example 3 A glass container with a lid was immersed in a constant temperature bath, hydrogen peroxide was not added before continuously adding nitric acid and hydrogen peroxide, and during continuous addition, nitric acid was added at 0.41°C.
wt/m2 and hydrogen peroxide at a rate of 0.17 sd/- for 5 hours and 5 minutes for both. During the test, no generation of nitrogen oxide gas was detected, except for the 16 minute period from 2 hours 36 minutes to 52 minutes after the start of continuous addition of nitric acid and hydrogen peroxide, at a maximum concentration of 150 ppm. The sample silver powder dissolved 949 after 6 hours and 5 minutes.

Comparative Example 4 Except that l〇- of hydrogen peroxide was added before continuously adding nitric acid and hydrogen peroxide, and during continuous addition, hydrogen peroxide was added at a ratio of 0.15 d/-. All Example 3
The bis 1st grains were dissolved in the same manner as above. Immediately after the start of continuous addition of nitric acid and hydrogen peroxide, nitrogen oxide gas began to be generated, reaching a maximum so ppm 2 minutes later, decreasing thereafter, and no gas generation was detected after 30 minutes. The liquid temperature showed 5 s°C 5 minutes after the start of continuous addition, and then gradually decreased.

The sample bismuth grains dissolved 70% in 4 hours.

As is clear from the above, according to the method of the present invention, a metal nitrate aqueous solution can be efficiently obtained in one step without generating nitrogen oxide gas, so that denitrification treatment equipment is not required. Furthermore, since the nine-nitrate aqueous solution obtained by this method does not contain any particular impurities, highly pure metal nitrate crystals can be obtained from it.

Patent applicant: Sumitomo Metal Mining Co., Ltd. Agent: Patent attorney Yasuzo Kaizu Same as: Patent attorney Hirayama - Kushi

Claims (1)

[Claims] A method for producing metal nitrates in which a metal is reacted with nitric acid, the reaction with nitric acid being accompanied by the generation of nitrogen oxide gas, characterized in that the reaction is carried out in the presence of a large amount of peroxide .