Pulling metals out of the ground is nothing new, and it has been done for many years. Copper is one of those things that the many mining companies around the world look for. This chemical element is known for its high thermal and electrical conductivity, something that makes it valuable for construction, plumbing, and electrical work around the globe.

Mining companies, especially the big publicly traded ones, tend not to focus solely on copper. The three companies in this article look for various other elements, something that gives them more diversity for our portfolios. The companies that we’ll take a look at are Rio Tinto plc (NYSE:RIO), BHP Billiton Limited (NYSE:BHP) and Freeport-McMoRan Copper & Gold Inc. (NYSE:FCX).

Rio Tinto

Rio Tinto’s HQ is in the UK, but the company is a multinational British-Australian miner that combs the planet looking for copper, aluminum, gold, diamonds, coal, uranium and more. They have been incredibly successful over the company’s long life, and I believe that their success will continue for many years to come.

Sales at the mining giant have grown from $9.23 billion in 2003 up to $60.54 billion in FY 2011. Net income during that same period grew from $2.16 billion up to $5.84 billion. Assets at Rio Tinto have also grown over the period from $24.08 billion to $119.55 billion in FY 2011. Those assets, the mines, are spread throughout the world with more focused amounts in Australia and Canada, the current mining capitals of the world.

This company has a pretty high P/E of 24.9 at the time of writing, something worth looking out for. The price to sales ratio is relatively low compared to industry though at just 1.93. Price to book isn’t too high either at 1.85. I like the low debt/equity ratio that the company has (just 0.38), and although I prefer no debt, when a company is the size of Rio Tinto with various projects around the world, I think they’re pretty secure.

Of course, there are some negatives with the company. I don’t like the low ROE, ROA and ROC, which sit at 6.99%, 3.9% and 4.8%, respectively. Those numbers lag the industry. If you are planning an investment you should also be aware of the foreign exchange risk that is present in such a large, multinational company.

BHP Billiton

BHP Billiton, like Rio Tinto, is a British-Australian mining monster. This company mines copper, diamonds, gold, aluminum, silver, petroleum and even natural gas. BHP Billiton is the largest mining company in the world if you measure based on 2011 revenues.