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What is lead sinter and how is it produced?

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Metallurgy — lead processing A zinc-lead blast furnace and lead-splash condenser. This technology is utilized mainly for producing zinc while managing both lead and zinc from raw materials, a technique that was highly influential in 20th-century smelting.

Lead sinter is a brittle, lumpy material produced during the lead processing stage known as indirect smelting. It consists of a mixture of lead, zinc, iron, and silicon oxides, along with lime, metallic lead, and residual sulfur.1

The production of sinter involves a process called roasting, which serves two primary purposes: removing the majority of the sulfur from lead concentrates and agglomerating fine flotation products so they remain stable within a blast furnace.1

The process is carried out as follows:
* Preparation: Lead concentrate is mixed with various fluxing materials, such as limestone or iron ore.1
* Roasting: The mixture is spread onto a moving grate where air is blown through at temperatures reaching 1,400 °C (2,550 °F). During this stage, the sulfur in the ore acts as a fuel, combusting into sulfur dioxide gas.1
* Fusion: The heat fuses the remaining ingredients into a solid, brittle mass.1
* Discharge: As the material is discharged from the grate, it is broken into lumps, creating the final sinter ready for charging into the blast furnace.1