Metal dissolution process

DETAILED DESCRIPTION What is claimed is: 1.
A method for prevention of evolution of NOx fumes in the dissolution of metal values in mineral acid solutions containing HNO.
sub.
3 which comprises adding hydrogen peroxide to said acid solution, maintaining the hydrogen peroxide concentration during the dissolution at between about 1 and about 20 grams per liter and the mole ratio of hydrogen peroxide to mineral acid at a value of less than 0.
273.
2.
The method of claim 1 in which the dissolution is carried out at temperatures in the range from about 10.
degree.
to about 70.
degree.
C.
3.
A process of claim 2 in which said temperatures range from about 20.
degree.
to about 55.
degree.
C.
4.
A process according to claim 1 wherein a hydrogen-peroxide stabilizer is added to the acid solution.
5.
A process according to claim 4 wherein the hydrogen peroxide stabilizer is selected from fatty acids, glycerine, glycols, allyl alcohol, crotyl alcohol, cis-1,4-but-ene-diol, phenol, p-phenol sulfonic acid or salts thereof or p-methoxy phenol.
6.
A process according to claim 4 wherein the hydrogen peroxide stabilizer is ethylene glycol.
7.
A process according to claim 1 wherein the mineral acid solution is a mixture of nitric acid and at least one acid selected from sulfuric acid, hydrofluoric acid and hydrochloric acid.
8.
A process for bright dipping copper or copper alloys without evolution of NOx fumes which comprises immersing the copper or copper alloy in a bright dip acid solution containing from about 430 to about 460 grams per liter of H.
sub.
2 SO.
sub.
4, from about 100 to about 150 grams per liter of HNO.
sub.
3 from about 0.
2 to about 3 grams per liter of HCl and from about 8 to about 12 grams per liter of hydrogen peroxide.
9.
The process of claim 8 wherein the acid solution also contains a hydrogen peroxide stabilizer.
10.
The process of claim 8 wherein the acid solution also contains a surface passivation agent.
11.
A bright dip solution for copper or copper alloys comprising: from about 430 to about 460 grams per liter of H