Slag fuming furnace operation

The first feed went into the KIVCET furnace on March 31, 1997. The start-up of the new slag-fuming furnace was three months later in June 1997. The initial period of operation was hampered by mechanical problems that prevented sustained periods of operation imtil a major shutdown in November 1997 when several mechanical deficiencies were corrected. This... 

With increased focus on the recovery of metal values in stockpiled slags and residues, impurity control becomes an even more important consideration. Operation of the KIVCET furnace at design capacity and the restart of one of the older slag fuming furnaces have enabled treatment of these stockpiles. As the stockpiles were being accumulated they formed natural bleeds for undesirable impurities such as the halides, and now the challenge will be to control... 

Details of operating conventional slag fuming furnaces are given in Table 8.2. 

There are numerous sources of fumes from the furnace operation, such as dust from the raw materials feeding and fumes emitted from electrode penetrations and tapping. These fumes, which consist of dust, phosphoms vapor (immediately oxidized to phosphoms pentaoxide), and carbon monoxide, are collected and scmbbed. Principal wastewater streams consist of calciner scmbber liquor, phosphoms condenser and other phossy water, and slag-quenching water. 

The complex system of recycle streams betwe i and within each of ftie operating units ensures a higih overall recovery of the major products. For example, lead, bismuth and precious metals are recovered firom both the lead concentrates and the zinc concentrates treated. Recovery of lead is also significantly enhanced by operation of ftie slag fuming and oxide leaching circuits. Lead not recovered directly to bullion in the KIVCET furnace is recycled... 

The Kivcet Process (an acronym in Russian for oxygen flash cyclone electrothermal process), was developed by the Vniitsvetmet Institute in Kazakhstan in 1967 for the treatment of both copper and lead concentrates (Sychev et al, 1985). A 25 t/d pilot plant was built and operated for a number of years followed by a plant to treat 500 t/d of mixed copper-zinc concentrates at Glubokoe in 1970. That plant produced a copper matte and zinc rich slag for slag fuming in the electric furnace to recover zinc oxide. 

Fig 8.8 - Average overall fuming rate versus tail slag composition (50 tonne capacity furnace - batch operation). 

Zinc fuming rates in the electric furnace were directly proportional to the power input, with 180 kg of zinc per hour per square metre of furnace area obtained at a power density of 1000 kW/m of furnace area. The zinc level in residual slag could be reduced to less than three per cent and lead to less than 0.2 per cent. Zinc fuming rates for other previous fuming operations using AC submerged arc resistance furnaces range from 10 to 70 kg of zinc per hour per square metre of furnace area. 

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