For many years lead has been considered the dead man walking of metals. A poor public image, fuelled by stories of lead poisoning due to lead contamination of air and water, have long been seen as justifications for the metal’s demise in common use. However, it is still produced in large quantities to meet demand for lead-acid batteries. Its LME price no longer lags zinc; the twin metals now vie for investor interest. However, how the metal is produced, and from what, will define the future of the industry especially whilst public opinion is focussed on a greener circular economy agenda.
If you are looking for more details, kindly visit our website.
The lead smelting industry is split clearly into two areas:
But as is the case in many smelting industries, primary smelters have stepped onto the turf of the secondary ones and many primary lead smelters also process used lead-acid batteries.
Having said this, outside of China less than 20 primary smelters are still in operation (see Figure 1), but with a potential capacity of around 2.2M tonnes of lead. A typical primary lead smelter has a capacity of between 100 to 200kt.
Figure 1 ROW Smelting technology distribution. Definitions of terms used in Figure 1 - TSL : Top Submerged Lance, BF : Blast Furnace, QSL : Queneau Schuhmann Lurgi lead smelting process, EF : Electric Furnace, SKS : ShuiKouShan lead smelting process, ISF : Imperial Smelting Furnace, Slag Only : where a smelting process is processing high lead bearing slag
Primary Lead …. Had its day or still has a place? What does ESG say?
The primary industry may not be huge, but it does have a significant number of smelting and refining technologies in use. The traditional primary smelting route was the sinter plant and blast furnace combination. The sinter plant can be a difficult operation to control in terms of fugitive emissions to air of both lead and SO2, and so new processes were developed.
Skarn is currently working on a primary lead smelter GHG & Energy analysis. We are also working on a secondary smelter analysis to ‘close the gaps’ on downstream operations.
As new direct smelting technologies: QSL, Kivcet & the Top Submerged Lance (TSL) variants like Isasmelt and Ausmelt were developed, the sinter plant-blast furnace combinations were replaced. This was especially so in China, where the Chinese developed SKS process came to dominate lead production in the last decade. Having said this. still some blast furnace plants linger on there.
In terms of Green House Gas (GHG) emissions, blast furnaces use large amounts of coke, the direct processes use more power, typically for the production of oxygen. Thus, GHG emissions can be very site specific depending on what is the source of the power being used by the smelter. However, for a lead smelter based in Europe, Figure 2 shows the typical Scope 1 and Scope 2 emissions depending on the technology used.
Figure 2 Scope 1 & 2 emissions for typical lead smelter technologies
The use of hydrocarbons like coal, coke natural gas and fuel oil may be the subject of replacement by green hydrogen in the future. Most notably, as the direct processes also need oxygen, so a green hydrogen hydrolyser producing both hydrogen and oxygen from water would reduce GHG emissions for the direct processes further. This is not the case for a blast furnace where all the coke cannot be replaced by hydrogen; a significant proportion, well over 50%, will still be needed as burden support.
In terms of ESG, the direct processes in the primary sector should survive as long as developments, such as green hydrogen replacement, come to fruition. But are the processing units too big, sized for processing concentrate feed, and wrongly situated, located for the transport and processing or concentrates rather than recycling batteries? Lead concentrate is typically produced as a co-product to zinc and contains significant quantities of precious metals. Lead smelters are also the processing option for such precious metals residues from zinc smelters; the pair often being sited together. Primary lead smelters can also process used lead-acid batteries. Without a complete upheaval therefore in the zinc and lead supply chain, primary smelters would appear to have a future …. at least those embracing direct smelting along with the ESG agenda!
Secondary Lead…. Small, simple, the ESG way to go?
The picture for the secondary industry is completely different and is due to the fact that in comparison with primary smelters the processing technology is much simpler. There are close to 100 plants of 50-100kt capacity; but even more below this, especially in less well developed countries such as India, Mexico and China.
A typical secondary smelter will have some method of breaking the used battery, the metal contents are then smelted, refined and cast into lead product. The smelting stage can be a blast furnace like that used in the primary sector, but they are far smaller in size; the true work horse of the secondary industry is the rotary furnace, and notably in the USA the reverberatory furnace. The typical secondary refinery will be pyrometallurgical but will only have a few kettles rather than the large units used by primary smelters.
This small size means the secondary smelters can be closer to their market for the supply of used batteries and the supply of new lead units. But this, accompanied with the simplicity of the technology, means that secondary lead smelters have the potential for very poor ESG performance. The huge number of small capacity plants worldwide mean that consistent alignment to regulations is likely impossible.
If you want to learn more, please visit our website RE TECH.
In terms of GHG emissions, as can be seen in Figure 2, a typical secondary lead smelter is a much low emitter than its primary compatriot. This is driven by the lower energy consumption of the typical plant : automated battery breaking and based around rotary furnace smelting. It is the problem of uncontrolled emission of lead to air and water that is the potential issue, and with it the potential social issues.
In areas such as Europe and the USA, the secondary lead smelters are under close monitoring, and thus modern, very low emission operations exist. It is in less developed areas where the problems are likely to occur, not helped by less stringent limits.
Clearly a rationalisation of the “lower” end of the secondary smelting industry is needed. This would also make the logistics of battery recycling more environmentally compliant. Big loads going into environmentally controlled, large capacity battery breaking operations close to market. Not the current situation: loads of loads of scrap batteries into a potential environmental free for all!
So, what is the future like?
We believe that both the primary and secondary sectors have a place in the future manufacture of lead.
However no new primary plants are likely unless significant surpluses in the lead concentrate market are foreseen. Any increase in battery recycling capability will be taken up with additional secondary capacity. But both industries will be in the ESG spotlight to ensure lead is no longer the dead man walking.
We expect to see primary smelters using direct smelting processes with green hydrogen and renewable power; and as to be seen at Port Pirie with hydrogen as a potential further revenue stream. These plants are likely to process both lead concentrate feed and used batteries.
We also expect modern secondary smelters based on their traditional rotary furnace flowsheet located close to market and operating under very close monitoring to match their “intown” sites. With these plants processing used batteries.
Skarn is currently working on a primary lead smelter GHG & Energy analysis, which is expected to be launched towards the end of August. We are also working on a secondary smelter analysis to ‘close the gaps’ on downstream operations.
For further information regarding the forthcoming Lead Smelter GHG & Energy product please contact john.anderson@skarnassociates.com or fernandoaraya@skarnassociates.com.
Boliden’s lead smelter in Bergsöe is one of Europe’s biggest recyclers of used lead-acid batteries and as such plays an important part in the metal’s life cycle.
At Boliden Bergsöe the lead from 4 million worn-out lead-acid car batteries is recycled every year. At least 70 per cent of the lead produced here is sold to the battery industry in Europe and used again.
“Our lead smelter helps recover and recycle a finite resource that is of great importance to modern society, but which can be extremely toxic if not handled in the right way during smelting and recovery,” says Fredrik Kanth, acting General Manager at Bergsöe.
Minimised environmental impact
Bergsöe seeks to minimise the environmental impact of its emissions to air and water, and the plant exceeds both national statutory requirements and EU requirements. The total lead discharge to water in 2016 was 1.3 kg, compared with 3.5 kg, the level stipulated in the environmental permit. The plant already meets most of the regulations in the EU Industrial Emissions Directive for the Best Available Techniques in the Non-Ferrous Metals Industry, which will become mandatory as of 2020.
Ultramodern systems take care of waste water containing sulphuric acid and scrub process air, including lead-bearing extraction air, and collect filtered particles for recycling externally. Ash from crucibles, casting machines and lead-bearing slag is also processed on site.
District heating from worn-out batteries
Worn-out batteries contain plastic that serves as a reducing agent in lead production. The plastic also gives off heat together with the coke used during the smelting process. The residual heat, equivalent to the annual heating requirement of 2,000 homes, is supplied to Landskrona municipality’s district heating system.
DID YOU KNOW THAT...? Lead is one of the most recycled metals and around 99 per cent of lead-acid batteries are recycled in Europe. The lead in the batteries is fully recyclable. The greater part of the recycled lead is sold back to the battery industry, which uses it to make new batteries.
Text: Richard Cutler
Photo: Stefan Berg
The company is the world’s best lead smelting plant manufacturer supplier. We are your one-stop shop for all needs. Our staff are highly-specialized and will help you find the product you need.