Production
The production of pure platinum group metals normally starts from residues of the production of other metals with a mixture of several of those metals. One typical starting product is the anode residue of gold (other fast refining methods used today), copper or nickel production. The differences in chemical reactivity and solubility of several compounds of the metals under extraction are used to separate them.
A first step is to dissolve all the metals in aqua regia forming their respective Cl-complexes. If silver is present, this is then separated by forming insoluble silver chloride. Rhodium sulfate is separated after the salts have been melted together with sodium bisulfate and leached with water. The residue is then melted together with sodium peroxide, which dissolves all the metals and leaves the iridium. The two remaining metals, ruthenium and osmium, form ruthenium and osmium tetroxides after chlorine has been added to solution. The osmium tetroxide is then dissolved in alcoholic sodium hydroxide and separated from the ruthenium tetroxides. All of these metals' final chemical compounds can ultimately be reduced to the elemental metal using hydrogen.
Read more about this topic: Platinum Group
Famous quotes containing the word production:
“From the war of nature, from famine and death, the most exalted object which we are capable of conceiving, namely, the production of the higher animals, directly follows. There is grandeur in this view of life, with its several powers, having been breathed into a few forms or into one; and that, whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved.”
—Charles Darwin (1809–1882)
“The growing of food and the growing of children are both vital to the family’s survival.... Who would dare make the judgment that holding your youngest baby on your lap is less important than weeding a few more yards in the maize field? Yet this is the judgment our society makes constantly. Production of autos, canned soup, advertising copy is important. Housework—cleaning, feeding, and caring—is unimportant.”
—Debbie Taylor (20th century)
“It is part of the educator’s responsibility to see equally to two things: First, that the problem grows out of the conditions of the experience being had in the present, and that it is within the range of the capacity of students; and, secondly, that it is such that it arouses in the learner an active quest for information and for production of new ideas. The new facts and new ideas thus obtained become the ground for further experiences in which new problems are presented.”
—John Dewey (1859–1952)