Lead Refining Plant
Lead Refining Plant
Product Description
Lead Refining Plant
Mettherm provides lead refining equipment for providing lead as per the international purity standard of secondary lead i.e. 99.97% and above.
The Process:
The lead received from Rotary Furnace is called hard lead /crude lead .The lead tapped from the furnace has to be cleaned from residual oxides and slag. After stirring for a while the impurities settle at the surface and are skimmed off.
The refining of crude lead takes place in a refining kettle at temperatures between 400°C and 550°C. If only battery scrap is used for lead production, 2 subsequent refining steps are required:
1. Removal of Cu which might have entered the melts through copper wires.
2. Removal of antimony originated from the former grid metal to produce pure lead.
Crude lead originating from battery scrap is normally alloyed with copper and antimony and also some traces of Ca, Sn, As, Zn in order to remove the unwanted elements. By adding sulphur to the lead melt and after stirring for some time, a Pb/Cu2S-dross (and if present with minor parts of Zn, Sb, As) is formed and skimmed off.
This de-copperisation step should be carried out at least two times or more to secure the refining result. The de-copperised lead still contains a large amount of antimony (and maybe some Sn, As). All of these elements can be removed by oxidation. For that purpose air or oxygen-enriched air is blown into the melt and stirred.
The different oxides formed settle at the surface and can be skimmed off. The oxidizing process is completed when mainly lead oxide is formed. Instead of oxidizing the impurities by injecting air, sodium nitrate (NaNO3) can be added. Here again a dross containing the impurities (and lead) is formed, which is skimmed off after wards.
It is obvious that the success of the refining has to be controlled by chemical analysis.
The refined metal is cast into ingots for shipment, sale or further manufacturing.
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Characteristics: