Steel is the most recycled material in the world. Sources of scrap steel range from steel cans collected in municipal recycling programs to old automobiles. Steels vary in composition, in order to qualify as a steel the material must consist of iron and a small percentage of carbon (greater than 1.7%). Additional ingredients, such as manganese, chromium and nickel, can be alloyed in to alter the properties of the steel. Due to steels high iron content it exhibits magnetic characteristics, except stainless steel due to a higher content of alloys such as chromium. The magnetic characteristics of steel is utilized to separate steel from other metals and materials using a large magnet. Magnets are also used in MRFs to seperate the steel from other containers on the sorting line.

Many communities operate recycling programs for household sources of steel such as appliances and steel cans. Most Canadians have convenient access to steel can recycling, through curbside, drop-off , and buyback programs. The recycling and collection of automobiles often falls into the hands of private business who process the cars using large crushing machines and then extract the steel using magnets to then be old to steel producers.

There are two standard processes for making steel. The Basic Oxygen Furnace process uses a minimum of 25% recycled steel. The Electric Arc Furnace process uses almost 100% recycled steel. For every ton of steel recycled, 2,500 pounds of iron ore, 1,400 pounds of coal, and 120 pounds of limestone are conserved.