Reaction of zinc ore sulphidic concentrates and zinc bearing materials  with air (enriched or not with O2).

Zinc bearing materials are reacted with air (enriched or not with O2) at 954°C to 1100°C (1750°F to 2000°F). Stockpiling of the sulphidic-concentrates, and optionally, other primary or secondary zinc-bearing materials in isolated storage zones or silo’s. - Sampling and laboratory analysis - Blending of the materials before feeding the furnace - Feeding of the blend by enclosed belts up to the furnace mouth. - Roasting at elevated temperature: about 950°C according to the feed composition or higher by blowing air enriched or not with O2. The air oxidizes the zinc sulphide to solid zinc-oxide and Sulphur Dioxide collected in the gas cleaning system together with some volatile components and entrained particles from the furnace in the gas-cleaning system. A by-product of the roasting 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 in concentrates is oxidized to zinc oxide; depending on iron content at the roasting the remaining zinc is linked to iron forming zinc ferrite at roasting temperature; zinc oxide and zinc ferrites are the main components of the Intermediate EC 273-776-3. The main reaction is to transform the polymetallic sulphide into an oxidic complex material (calcine) - The intermediate (Calcine) is collected automatically from the furnace 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 calcine is typically used in the production of zinc salt solutions - The zinc calcine is transferred to silo’s near the Leaching plant, 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 - The mixture is continuously fed to leaching tanks (closed loop of acidic solution, mostly sulphate) used in the production of (Intermediate) Zinc salt solutions.

Calcines, zinc-ore conc. is the product of the reaction of zinc sulphidic-concentrates, and optionally, other primary or secondary zinc-bearing materials which is roasted in furnace at elevated temperature or blow with air. It is a solid consisting  primarily of ZnO, ZnFeO2, ZnSO4 and a composite of metallic oxides and that is continuously fed to leaching tanks (closed loop of acidic solution, mostly sulphate) used in the production of (Intermediate) Zinc salt solutions.

Acute toxicity - inhalation

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)