HEAVY METAL RECOVERY IN FERROUS METAL PRODUCTION PROCESSES

摘要

A process for the production of ferrous metals or alloys thereof in which Zn and other heavy metals are recovered from the iron-bearing flue dust and the iron dust residue is returned to the furnace. The iron bearing flue dust is first separated from the furnace flue gases and leached in an alkali metal hydroxide solution having a concentration greater than 5m and pulp density of 1 : 1.5 to 1 : 8 at a temperature between 80 DEG C and the boiling point of the solution. The residue is then separated from the pregnant solution and washed before it is returned to the furnace. After purification and clarification of the pregnant solution, the Zn and other heavy metals are recovered to regenerate the solution which is subsequently recycled. After the iron dust residue has been washed it may be roasted with sodium carbonate at above 700 DEG C and leached in a caustic solution. Also, the flue dust may be subject to a dilute leach the dilute leach residue then being reducted by roasting prior to the main leached step.