The newly developed green leaching processes for chromium, lead and gold extraction from ores or concentrates are described. The chromium is extracted from the iron chromite ore with fused sodium hydroxide at 500-550 degreesC as sodium chromate. The galena in lead sulfide concentrate is converted into lead carbonate in ammonium or sodium carbonate solution at 50-80 degreesC followed by the separation of lead carbonate formed from the unconverted sulfide ores by flotation. Gold associated with sulfide ore (such as pyrite and chalcopyrite) can be extracted into sodium thiosulfate solution without any pretreatment such as roasting, high pressure aqueous oxidation or bacteria pre-leaching.