Refractory Materials For Lead Smelting

The basic method for lead smelting is the sintering blast furnace method (i.e., the roasting-reduction smelting method). The furnace types include blast furnaces, lead-zinc closed blast furnaces, QSL (oxygen bottom-blown) furnaces, and KIVCET direct smelting furnaces.

Refractory Materials for Lead-Zinc Closed Blast Furnaces
The lead-zinc closed blast furnace is a new type of furnace that combines lead smelting and zinc smelting to process lead-zinc oxide ores or lead-zinc mixed sulfide ores. It is a thermal device capable of directly producing lead and zinc. The lead-zinc closed blast furnace mainly consists of a closed blast furnace, a condenser (i.e., a lead mist chamber), a flue, and is connected to lead and zinc refining equipment.

A standard furnace has 36 tuyeres with a tuyere area of about 10m². The working layer of the furnace hearth lining and the water-cooled panel lining of the furnace waist are generally built with magnesia-chrome bricks. The non-working layer of the furnace hearth and other parts of the furnace body are built with clay bricks and dense clay bricks. High-alumina cement refractory castables are commonly used for on-site casting of the furnace top and the inclined channels connecting the lead mist chamber, although these can also be made as precast blocks for hoisting and masonry. The bottom and top of the lead mist chamber are built with dense clay bricks or high-strength refractory castables. The side walls, which are subject to erosion by lead mist and chemical attack, deteriorate quickly and need to be built with clay-bonded silicon carbide bricks. The rotors and shafts inside the lead mist chamber are made of graphite or silicon carbide materials. Ordinary clay bricks are used for the flue and other areas.

The furnace generally has a lifespan of 3 to 4 years. The linings of the feed port, furnace waist, tuyere area, and slag line area are prone to damage and require several minor repairs during each furnace campaign. The lead mist chamber and flue have a lifespan equivalent to several furnace campaigns, but the rotor and shaft need multiple replacements. The bottom and top of the lead-zinc separation chamber are usually built with clay bricks or dense clay bricks, with the non-working layer of the side walls built with clay bricks and the working layer with magnesia-chrome bricks. The bottom of the lead trough and lead discharge trough is built with high-alumina bricks with an Al₂O₃ content of 65%, and the walls with magnesia-chrome bricks or chrome bricks. The trough can also be cast with refractory castables of the same material to form a strong integral lining. The cover plates of the trough are made of precast blocks of high-alumina cement refractory castables. The linings of the lead-zinc separation chamber and trough are in relatively good condition, suffer little damage, and can last for several furnace campaigns. The combustion chambers, heat exchanger rooms, and chimneys of the lead tower and zinc tower are generally built with clay bricks and can also last for several furnace campaigns.