Kennecott Garfield Smelter Stack



Kennecott Utah Copper LLC’s Garfield Smelter Stack is a 1215 ft high smokestack west of Magna, Utah, alongside Interstate 80 near the Great Salt Lake. It was built to disperse exhaust gases from the Kennecott Utah Copper smelter at Garfield, Utah. It is the 60th-tallest freestanding structure in the world, the 4th-tallest chimney, and the tallest man-made structure west of the Mississippi River.

Waste gases
The Garfield Smelter Stack was completed in 1974, replacing several earlier smokestacks, the tallest of which was 413 ft high. The extra height was needed to meet the requirements of the Clean Air Act of 1970, to disperse waste gases according to new standards.

In response to new emissions limits and anticipated future state and federal standards, Outokumpu and Kennecott had conducted flash converting pilot tests from 1985 at Outokumpu's research facility in Finland. With the introduction of strict new environmental regulations in the state of Utah, the smelter's maximum permissible sulfur emission was decreased to 1082 ST per year from the earlier 18574 ST. In 1995 a new, cleaner flash smelting furnace was commissioned. By 2004, the annual average SO2 emissions from the stack were 161.5 lb/h (73 kg/h), below the permitted average annual level of 211 lb/h (96 kg/h) (with a three-hour permitted SO2 limit of 552 lb/h (250 kg/h)).

The off-gases from the flash smelting furnace contain 35–40% sulfur dioxide. They are cooled and cleaned in a waste-heat boiler, electrostatic precipitator and scrubbing system before being sent to the sulfuric acid plant. The acid plant produces either 94% or 98% sulfuric acid with tail gas containing typically 50–70 ppm sulfur dioxide, resulting in a measured sulfur fixation of greater than 99.9%. In 2006, the company produced and sold approximately 833000 ST of sulfuric acid, made from the formerly released gas. The acid recovery plant is designed to also recover waste heat from the process to produce electrical power. Approximately 24 MW of electrical power is generated, representing 70% of the smelter’s electrical requirements.

Design and construction
The stack is 177 ft in diameter at the bottom with 12 ft walls, and rises directly from the ground. At the top it is 40 ft in diameter and 12 in thick. A large fiberglass duct passes up the stack and carries gases to the top.

26317 cuyd of wood and 900 ST of steel were used in its construction. Construction commenced on August 26, 1974 and finished on November 19, an 84-day concrete pour. It cost $16.3 million at the time to build, equivalent to $ in.

The top can be accessed by a Swedish-built elevator that crawls up a gear track on the inside surface. It takes 20 minutes to ascend the stack, although workers only need to travel up to the 300-foot level each day, to service the air-sampling station.

The Garfield Smelter Stack is the tallest free-standing structure west of the Mississippi River, the fourth tallest smokestack in the world and the fifty-ninth tallest free-standing structure on earth. It is approximately as tall as the Berlin TV Tower, the Bank of China Tower in Hong Kong, or the Bank of America Tower in New York City. It is the only operating smelter chimney left in Utah.