METHOD FOR EXTRACTING METALS FROM SOLID SLAG WHEN IT IS BEING DISCHARGED FROM COAL-FIRED BOILER, AND DEVICE FOR ITS IMPLEMENTATION Russian patent published in 2012 - IPC C22B7/04 C22B11/00 F22B33/00 

FIELD: metallurgy.

SUBSTANCE: solid slag is supplied from taphole to vacuum furnace during coal firing so that molten slag and gaseous oxides are obtained and removed from the furnace for further processing. Molten slag is tapped to ladle, blown with heated air and supplied to a centrifuge for separation of particles of precious metals. Heated pulverised coal is supplied to cleaned slag, and liquid drops of copper, iron, nickel, cobalt, vanadium, manganese and chrome, as well as vapours of reduced lithium and zinc are separated from slag. Reduced liquid and vaporous metals are continuously tapped from centrifuge for further processing. Then, slag is sprayed due to centrifugal forces, and sprayed slag drops are pre-cooled till their surface is hardened in opposite moving cooling medium flow. Then, they are collected, exposed in slag accumulator and cooled with air in slag cooler. In addition, the air heated in slag cooler is used in boiler burners and for blowdown of molten slag that is cooled in condenser after it hardens the slag. Condensate is used for pre-cooling of sprayed slag.

EFFECT: elimination of leaks of cold air and water vapours to boiler furnace through taphole; separation of precious metals; afterburning of unburnt carbon; extraction of iron and other non-precious metals from slag, including environmentally hazardous ones, as well as use of slag heat for heating of compressed air.

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