Industrial uses
This is an orange, crystalline substance with a specific gravity of 2.68. Solubility in water is
11.7% at 20 °C. Both potassium and sodium dichromate are used in mineral processing.Dichromate solutions have an acid reaction because Cr
2O
72- ion reacts with water as follows:
H2O + Cr
2O
72- ? HCr
2O
4- + H
+ + CrO
4-Salts of chromic acid in acid medium are oxidants (Cr
4- changes to Cr
3- ). In principle,
dichromates are used in selective separation of copper–lead bulk concentrates, usually in
acid pH. A mixture of sodium dichromate and sodium silicate has shown to be an excellent
lead depressant during copper flotation from a bulk copper–lead concentrate containing
secondary copper minerals.
