Sulphidic Zn-Pb concentrates and other zinc bearing materials

The sulphidic-concentrates are stockpiled (optionally) along with other primary or secondary zinc-bearing materials in isolated storage zones or silo’s. Sampling and laboratory analysis can be performed. The materials are blended before feeding the sinter band by enclosed belts up to the sinter band feed grid. Roasting and sintering then occurs at elevated temperature: about 1150°C according to the feed composition or higher by blowing air enriched (or not) with O2, up-drought or down-drought. The air oxidizes the zinc-lead sulphide to solid zinc-lead-oxide/sulphate and Sulphur Dioxide collected in the gas cleaning system together with some volatile components and entrained  particles from the sinter band in the gas-cleaning system. A by-product of the sintering is sulphur dioxide, which is marketed as such (liquid) or further processed into sulphuric acid, a commodity. The gas cleaning system aims at collecting dust and impurities before the sulphuric acid plant or SO2 condensation. Most of zinc-lead in concentrates is oxidized to zinc-lead oxides; depending on iron content in the feed, during the sintering process, zinc is proportinately linked to the iron present, forming zinc ferrite; zinc and lead oxides, zinc ferrites and lead sulphate are the main components of the Intermediate EC 305-411-1. The main reaction is to transform the polymetallic sulphide into an oxidic complex material (calcine). The intermediate (Calcine) is collected automatically from the sinter band and allowed to cool down. If required, it can further be ground before being transferred to storage zones or silo’s through specially designed transfer units (i.e. pneumatic transport). In case of transport to other premises, the Intermediate will be loaded in containers (barrels, small containers, bulk containers, silo-trucks, bulk transport ships, barges …). The zinc calcine is transferred to silo’s near the smelt unit, pneumatically, hydraulically or by closed conveyor belts; it can also be unloaded from [pneumatic] transport trucks, trains, containers, ships, barges…and transferred  to storage zones or silo’s through specially designed transfer units, [reddlers, conveyor belts, ...]. The zinc calcine is optionally blended with other Zinc-containing oxidic recovered materials and fluxing agents, if necessary for an adequate slag composition in the furnace. The mixture is regularly fed with reducing agents (e.g.coke) to the smelting units (e.g. Imperial Smelting Furnace) where zinc metal is eventually produced.
The calcine is typically used in the pyrometallurgical production of zinc and lead metal, as by-product.

Product of the reaction of zinc ore concentrates with air at 954°C to 1010°C (1750°F to 1850°F). Consists primarily of ZnO, ZnFeO2, ZnSO4 and a composite of metallic oxides. The calcine is typically used in the pyrometallurgical production of zinc and lead metal, as by-product.

Acute toxicity - oral

Skin corrosion / irritation

Serious eye damage / eye irritation

Carcinogenicity

Reproductive toxicity

Specific target organ toxicity - repeated (STOT-RE)

Hazardous to the aquatic environment (acute / short-term)

Hazardous to the aquatic environment (long-term)