Cadmium

Cadmium is a soft, bluish-white, metallic element that can easily be shaped and cut with a knife. The atomic symbol is Cd, and the atomic number is 48. Cadmium melts at 321 degrees Celsius and boils at 765 degrees Celsius. Cadmium burns brightly in air when heated, forming the oxide CdO. In 1871, the German chemist Friedrich Stromeyer discovered cadmium in incrustations in zinc furnaces.

Rare greenockite is the only mineral bearing cadmium. Cadmium occurs most often in small quantities associated with zinc ores, such as sphalerite. Electrolysis or fractional distillation is used to separate the cadmium and zinc. It is estimated that at least 80% of world cadmium output is as a by-product from zinc refining. The remaining 20% comes from secondary sources and recycling of cadmium products. Cadmium recycling has been practical only from nickel-cadmium batteries and from some alloys and dust from electric-arc furnaces.

Cadmium is used primarily for metal plating and coating operations in transportation equipment, machinery, baking enamels, photography, and television phosphors. It is also used in pigments and lasers, and in nickel-cadmium and solar batteries.

Prices – Cadmium prices in the past 6 years have been at severely depressed levels, reflecting the decreased demand for the substance. Cadmium prices in 2003 rose 26% to 29 cents per pound from 23 cents in 2002. The 2003 price of 29 cents was an improvement from the record low of 14 cents in 1999 but it was still far below the 20-year average price of $1.59 per pound.

Supply – World cadmium production in 2002 fell to a 27-year low of 15,800 metric tons. China and Japan were the largest producers of cadmium in 2002, each producing 2,500 metric tons, representing 15.8% of world production. US production of cadmium in 2002 rose +3% to 700 metric tons from the record low of 680 metric tons in 2001. The US production level in 2002 was less than half the level seen just two years earlier. The US in 2002 accounted for just 4.4% of world production.

Demand – Consumption of cadmium has been declining fairly steeply in the last few years due to environmental concerns. Of the total apparent consumption, some 75 percent was for batteries. Another 12 percent went into pigments while coatings and plating used 8 percent. Stabilizers for plastics took 4 percent while nonferrous alloys and other uses took 1 percent.

Trade – The US in 2002 relied on imports for virtually none of its cadmium usage, down from 38% as recently as 1998. US imports of cadmium have plunged in recent years and in 2002 fell to a negligible 25 metric tons from 107 metric tons in 2001 and 425 metric tons in 2000. US exports of cadmium fell to 194 metric tons in 2002 from 272 metric tons in 2001.