Outotec’s Kaldo Technology concept provides user-friendly, environmentally sound and optimized solutions for production of Doré metal based on proprietary equipment and technologies.
Instead of using different vessels for roasting, smelting, reducing and converting, all these four steps can be executed in one single vessel, the Kaldo furnace. Because the converting operation also includes oxidizing of the selenium, selenium roasters are not needed. Instead Selenium is recovered at high purity from off-gases from the Kaldo furnace.
The Kaldo furnace is a compact and energy-efficient reactor with high capacity. Energy is introduced with an oxygen/fuel burner lance. Converting and refining is done with a special lance using air at supersonic speed, giving high oxidizing efficiency.
The process off-gases containing selenium are taken to a wet gas cleaning system consisting of a venturi scrubber unit, a wet electrostatic precipitator and an absorption tower.
The Kaldo furnace requires a minimum of maintenance thanks to special design features. The use of a spare vessel enables the re-bricking of the furnace outside its operating position. A newly relined vessel can replace an old worn-out vessel quickly and easily by simply lifting it out/in with an overhead crane.