Rio Tinto Kennecott is a fully integrated mining operation located just outside Salt Lake City, Utah, US. Kennecott is a wholly owned subsidiary of Rio Tinto.
For more than 110 years, Kennecott has been mining and processing minerals from the rich orebody of the Bingham Canyon Mine. In 1989, Rio Tinto acquired the Bingham Canyon Mine and other facilities in the Salt Lake Valley.
Kennecott is a strong economic driver and strives to be a valuable community partner through strategic partnerships, charitable giving and sustainable development practices.
Kennecott’s operations include the Bingham Canyon Mine, Copperton Concentrator, Garfield Smelter, refinery, power plant and associated facilities.
The metals and minerals Kennecott produces are essential for modern life. Kennecott produces copper, molybdenum, gold, silver and sulphuric acid to be shipped around the world.
Mine and crusher
At Kennecott, ore is extracted from the Bingham Canyon Mine. After blasting, the ore is carried to a crusher to break down the rock. The crushed ore travels by conveyor belt to the concentrator.
The ore is mixed with an aqueous solution and ground into a fine powder. It is then mixed with water, chemicals and air in flotation cells. This process causes the copper-bearing minerals to stick to air bubbles in the cells. When the bubbles float off the top, they are collected as a liquid concentrate that is 28 per cent copper.
The concentrate travels 27km to Kennecott’s smelter. It is dried and sent into a flash-smelting furnace, which separates it into several products, including a copper matte that is 70 per cent copper. After the copper matte cools, it is fed into several furnaces that remove most of the remaining impurities, achieving 99.6 per cent purity. We then cast the copper into 750 pound (340kg) anodes.
These anodes are sent to the refinery to be placed in an acid solution, interleaved with stainless steel cathodes. For ten days, an electric current passes between the anode and the cathode, causing the copper ions to migrate from the anode to the cathode. Other impurities, including gold and silver, drop off into the bottom of the tank where they are collected for further processing.
The electrolytic process forms a plate of 99.99 per cent pure copper. One anode will produce two cathodes, each weighing about 300 pounds (136kg). These copper cathodes are Kennecott’s finished products.
Many copper deposits also contain molybdenum, and Kennecott’s Bingham Canyon Mine is no exception.
The froth flotation process at the concentrator separates molybdenum, copper, gold and silver minerals. The molybdenum concentrate is filtered, dried and packaged to be shipped to roasting facilities that further process the concentrate into the base finished product – molybdenum oxide.
Gold and silver
Gold and silver are byproducts of the copper mining and smelting process. They follow the same production pathway as the copper ore from the mine to the smelter.
At the refinery, the copper anodes (which contain gold and silver) are lowered into an acid solution. Gold and silver drop off into the bottom of the tank as electrolytic slimes. These slimes are sent to the Precious Metals plant where the gold is separated from the silver. After the separation, the gold and silver are refined into a dry sand, which is melted and cast into bars.
Many of the world's most important metal ore bodies are sulphides – that is, mineral compounds that contain sulphur. The Bingham Canyon Mine contains veins of copper sulphide, so the ore extracted contains sulphur, which needs to be separated from the copper.
The smelting process breaks elements apart and sulphur is driven off as sulphur dioxide gas. Kennecott’s smelter is one of the most modern and cleanest in the world. It captures 99.9 per cent of the sulphur dioxide emissions produced.
The sulphur dioxide gas is cleaned and piped to a double-contact acid plant. There, the sulphur dioxide is converted to sulphuric acid. Kennecott produces about one million tonnes of sulphuric acid each year as a product of the smelting process.
The sulphuric acid is delivered to gold, copper, uranium, and beryllium metal producers, fertiliser producers, chemical manufacturers, power plants, steel companies, farmers, and companies involved in water treatment across the US.
Kennecott aligns business strategies and daily practices around sustainable development in order to strengthen the operation and products, build enduring communities, and provide lasting benefits for customers, employees and stakeholders.
Kennecott strongly believes in being stewards of the land. The company sets self-imposed environmental targets to drive continual improvement.
A core component of sustainable development is supporting and enhancing a sustainable economy near the operation. Kennecott’s continued success is based on its ability to secure access to people, land and capital, and make responsible investments in our future. Kennecott’s objective is to understand and maximise the benefits we can bring to the economy at local, regional and national levels.
Kennecott’s greatest asset is its employees. The company is committed to providing a safe and healthy workplace where people can develop to the full extent of their abilities. Kennecott builds enduring relationships with its people by treating them with fairness and decency at all times.
Wherever possible, Kennecott prevents, or otherwise minimises, mitigates or remediates any potentially adverse effects of the operation on the environment. This practice creates and sustains business value and reputation. Through Kennecott’s commitment and actions, the company strives to be a leader in environmental performance by demonstrating good management of natural resources, responsibly reducing the environmental footprint and exceeding community expectations for sustainable development.