CS262108B1 - Process for producing copper nitrate solution - Google Patents

Abstract

The solution relates to a method of producing copper nitrate for the preparation of catalysts from metallic copper and nitric acid. Oxygen or air and nitric acid with a concentration of 40 to 65% are simultaneously introduced into the reaction mixture. Nitric acid is added at a rate of 0.5 to 50 kg per 1 m3 of oxygen or air. Gaseous exhalations are brought into contact with wet copper. Dissolution can be carried out completely continuously. The obtained copper nitrate solution contains more than 200 kg Cu . m_:) and less than 0.1 kg . m~3 of ammonium ions. The amount of nitrous gases formed during dissolution does not exceed 0.2 kg NO2 per 1 kg of dissolved copper.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a process for the manufacture of a solution of copper nitrate having a copper concentration in solution of greater than 200 kg. m ^-3 suitable for the preparation of catalysts, by dissolving metallic copper in nitric acid to which oxygen or air is introduced during dissolution.

The prior art methods of preparing copper nitrate are by dissolving metallic copper in nitric acid without adding oxygen or air. When dissolving copper in nitric acid at a concentration greater than 35%, a copper nitrate solution at a copper concentration greater than 200 kg is obtained. m ^-3 which is suitable for the preparation of catalysts. During dissolution, however, considerable amounts of nitrogen oxides, toxic nitrous gases, are difficult to dispose of and costly to build up. The dissolution of copper in nitric acid above 35% is mainly due to the following chemical reactions:

Cu + 4HNO ₃ -> Cu (NO ₃ i ₃ + 2 H ₃ , 0 + 2 NO ₃

Ou 4- 8 HNO ₃ - * ₃ Cu (NO ₃ ) ₂ 4- 2 H, O +

4- 2 NO

This deficiency, i.e. the formation of nitrous gases, is partially solved by methods in which dilute nitric acid at a concentration of less than 15% is used, in addition to the above reactions, other chemical reactions take place.

4Cu 4-IOHNO 3 - 4Cu (NO 2) + 5H, 0 44-N ₂ O

Cu + 12HNO ₃ - 5Cu (NO ₃ ) ₂ + 6H ₂ O + + N ₂

Cu 4 -OHOH 3 - 4 Cu (NO ₃ ) ₂ + 3H ₂ O +

4- NH4NO3

The disadvantage of these processes is, besides the necessity of subsequent concentration of the obtained solution, also the content of ammonium ions in the solution, which do not allow the use of the copper nitrate solution for the preparation of catalysts. The same drawback is also found in the methods of dissolving metallic copper in nitric acid in the presence of a reducing agent such as hydrogen peroxide or urea, and in the presence of urea further reduces the reaction rate substantially and the need for energy supply.

A method for producing a copper nitrate solution having a copper concentration of more than 200 kg is directed to eliminating said drawbacks. m- ^{3 is} particularly suitable for the preparation of the catalysts according to the invention, characterized in that, during the dissolution of copper in nitric acid, oxygen and / or air are introduced into the reaction mixture during dissolution, while nitric acid is added in an amount of 0.5-50 kg / m ^{3 of} oxygen and / or air. The gaseous exhales are contacted with metallic copper, thereby reducing the amount of nitrous gases produced below 0.02 kg NO ₂ per 1 kg of dissolved copper. The copper nitrate solution prepared according to the invention contains more than 200 kg. m ^{-3 of} copper and less than 0.1 kg. m- ³ ammonium ions and is suitable for the preparation of catalysts. The dissolution of copper in the nitric acid of the present invention proceeds largely according to the total chemical reaction

Cu + + O I6HNO3 _3-7 Cu (NO _{3) 2} 44. 8 H ₂ O 4 N ₂

The following chemical processes take place on the surface of the metallic copper in contact with the fumes

Cu 4 NO _2i - * 4 CuO 4 N ₃

CuO 4- 8HNO ₃ 4Cu (NO ₃ ) ₂ 4- 4 H ₃ O

The advantage of the process according to the invention is, in particular, that in the course of dissolution minimal amounts of nitrous gases are formed, no expensive equipment is required for their disposal, the obtained copper nitrate solution has the desired concentration of copper and ammonium ions. A further advantage of the invention is that the cost of producing the copper nitrate solution according to said process is substantially lower compared to known processes; 2.3 moles of nitric acid are sufficient to dissolve 1 mole of copper.

Example

In a reaction column with a diameter of 300 mm and a height of 1200 mm filled with copper metal, 1/5 of the solution from the previous dissolution was left and air was introduced into the bottom of the column at a rate of 1.8 m ³ hr. ¹ and 50% nitric acid at a rate of 6-10 dm ³ .hr. ^-1 .

A total of © 36 dm ³ of nitric acid was added. The residual nitrous gases were fed to a column having a diameter of 150 mm, a height of 1000 millimeters filled with metallic copper, which was sprayed with 9 dm ^{3 of} water during dissolution. A total of 56.8 dm ³ of a 253 kg copper nitrate solution was obtained. m ^-3 and content 0.07 kg. m ~ ³ ammonium ions. The consumption of nitric acid was 2.28 kg of 100% HNO ₃ per kg of dissolved copper, and the exhalations during dissolution did not exceed 0.02 kg of NO ₃ per kg of dissolved copper.

Claims (3)

Process for producing a copper nitrate solution having a copper concentration in solution of more than 200 kg.m ^-3 suitable for preparing a catalyst, by dissolving copper in nitric acid, characterized in that during dissolution, oxygen or air and nitric acid are reacted into the mixture. concentration of 40-65% is added at a rate of 0.5-50 kg of nitric acid per m ^{3 of} oxygen and / or air. OF THE INVENTION 2. A method according to claim 1, wherein the gaseous exhales are contacted with wet metallic copper. 3. The process according to claim 1, wherein the dissolution is carried out continuously, wherein nitric acid, oxygen and / or air are introduced into the lower part of the reactor and the resulting copper nitrate solution is deburred from the upper part of the dissolution reactor.