Rio Tinto looking to upgrade Utah power plant as part of mine extension

International mining giant Rio Tinto said June 19 that it plans to invest $660m over the next seven years to extend the life of its Kennecott Utah Copper Bingham Canyon mine in Utah from 2018 to 2029, which would entail upgrades to a major on-site power plant.

The new investment includes the construction of mine infrastructure and new equipment to support pushing back the south wall of the mine. First ore from the south wall push back, which will be processed through existing mill facilities, is expected in 2017. The investment will enable production at an average of 180,000 tonnes of copper, 185,000 ounces of gold and 13,800 tonnes of molybdenum a year from 2019 through 2029.

Rio Tinto Copper chief executive Andrew Harding said: “This investment highlights the additional value we can create by the efficient investment of capital at existing tier one assets. It will secure low cost copper, gold and molybdenum production for the next two decades. We continue to evaluate underground options that will further extend the life of Bingham Canyon, which has already been in operation for more than 100 years.”

Work continues on evaluating projects to expand the tailings impoundment and upgrade the power plant, and obtaining permits for these projects, Rio Tinto noted in the June 19 statement.

The company noted in a March report that it has installed a new combined heat and power (CHP) system at the Kennecott Utah copper refinery. The CHP unit produces steam to meet the needs of the facility (about 70,000 pounds per hour) while efficiently co-producing 6 MW of electricity. The refinery CHP system became operational in December 2010. “It displaces 6 megawatts of electricity that would otherwise be sourced from more conventional processes (like coal),” the fact sheet added. “The Refinery CHP unit has been sized to meet the steam needs of the facility and co-produce approximately 50% of the electrical needs of the facility.”

The refinery CHP system, along with another CHP system, generates about 15% of Kennecott Utah’s total electricity requirements using renewable and/or alternative technologies. Other systems where renewable and alternative electricity systems are or will be installed include the following:

• A similar-sized CHP system at the MAP facility will co-produce approximately 6 MW of electricity and 60,000 pounds per hour of steam.

• A waste-heat power generation system at the smelter that captures waste heat from the two furnaces (the flash-smelting and converting furnaces) at the smelter’s acid plant (which captures 99.9% of SO2 emissions and converts it into sulfuric acid). The waste heat generates about 20 MW of electricity (about two-thirds of the smelter’s electrical power demand.)

• A solar photovoltaic system at the Reverse Osmosis Plant generates enough electricity for 65% of the building’s lighting needs.

Said a 2011 environmental stewardship report from the company about the site’s main power plant: “As part of our vision for the future, we plan to convert three boilers at the onsite power plant to combined-cycle natural gas, which will double the amount of power available while reducing air emissions by half. … Currently, the power plant produces about 175 megawatts (MW) using four boilers powered by either coal or natural gas. Upon receipt of internal and external approvals, three of the four existing boilers will be replaced with one natural gas turbine that can generate 175 MW and a new waste heat boiler. Heat recovered from the natural gas turbine’s exhaust will be used to power the three turbines formerly powered by steam from the existing boilers. The repowering project will double the power plant’s generating capacity to 350 MW. The efforts led to the December 2011 approval of an air permit for the power plant by the Utah Division of Air Quality.”

Rio Tinto is a leading international mining group headquartered in the United Kingdom, combining Rio Tinto plc, a London and New York Stock Exchange listed company, and Rio Tinto Ltd., which is listed on the Australian Securities Exchange.

About Barry Cassell 20414 Articles
Barry Cassell is Chief Analyst for GenerationHub covering coal and emission controls issues, projects and policy. He has covered the coal and power generation industry for more than 24 years, beginning in November 2011 at GenerationHub and prior to that as editor of SNL Energy’s Coal Report. He was formerly with Coal Outlook for 15 years as the publication’s editor and contributing writer, and prior to that he was editor of Coal & Synfuels Technology and associate editor of The Energy Report. He has a bachelor’s degree from Central Michigan University.