CLEANLEAD PROJECT: “DEVELOPING A NEW CONCEPT ‘CLEANLEAD’ FACTORY FOR EUROPE”
partially f ounded by the European Union within “GROWTH
PROGRAMME”. This Project had a duration of
three years, and it has been successfully accomplished
on April 2004.
Técnicas Reunidas S.A. (ES), Britannia Refined Metals Ltd (UK), Orzel Bialy S.A. (PL), Instytut Metali Niezelaznych (PL), Coventry University (UK), Lafarge Plasterboard Ltd (UK), Faculdade de Ciéncias da Universidade de Lisboa (P), Netherlands Organisation for Applied Scientific Research (NL), Magneto Special Anodes B.V. (NL), Membraan Applicatie Centrum Twente (NL), Kovohute Prĭbram A.S. (CZ), Institute for Nonferrous and Rare Metals (RO)
Secondary lead consumption is
r aise due to ever
increasing lead acid batteries demand for automotive
industry, and also related to new uses
such as the electric vehicles or
hybrid vehicles, solar and renewable energy storage ,
portable and auxiliary batteries in emergency systems, etc.
The lead battery recycling industry currently faces the challenge of
the conventional processes
aiming to avoid toxic waste s (slags, mattes, etc) generation
and trying to comply with the
more strict environmental regulations.
provides a new, low energy
cost, zero-waste generation sustainable option which
can improve substantially the
current lead smelting operations. The new process has been developed to deal
efficiently with the whole batter y
drained acid treatment, optimisation of the smelting stage and
hydrometallurgical treatment of the battery pastes.
Cleanlead Process Conceptual Diagram
The CLEANLEAD Process for drained acid treatment not only prevents the
current sludge for disposal
from being produced, but also turns
the acid into reusable products. Depending on the applied process option,
commercial synthetic gypsum , acid for new batteries refilling
or biotreatment of
effluents can be performed. This wide range of purposes
makes the described technology applicable
to different cases and
Detail of the gypsum product
Current processes turn the drained acid containing metallic impurities
into a waste sludge for disposal by adding lime. This treatment
associated environmental costs. The CLEANLEAD Process makes commercial synthetic
gypsum through drained acid purification by means of membrane techniques such
as diffusion dialysis and nanofiltration or chemical fits the
specifications to be used as feed
plasterboard industry, as an additive in the cement industry and in
floorscreeds manufacturing since the process can be
to get different gypsum products. Besides environmental advantages,
producing commercial gypsum versus an acid sludge
presents attractive economic revenue .
Membrane Electrolysis cell
electrochemical process allows obtaining a clean
and concentrated sulphuric acid (30% w/w) suitable for new
batteries refilling through
The CLEANLEAD Process also
of drained acid blended with other industrial alkaline effluents (landfill
leachates, etc) by means of biologically produced H2S to remove the impurities and getting
finally a non polluting stream.
OPTIMISED SMELTING OPERATION
Desulphurised battery paste smelting methods were developed within the CLEANLEAD project as an alternative to conventional raw paste smelting. Very positive results have been obtained in trials performed in a 500 kg rotary furnace, which are summarised as follows:
smelting temperature up to 900 ºC
• 3-4 times shorter smelting time
amount reduction by 65-75%
silica slag type being produced
reduc tion of
fluxes and reductants consumption
bullion yield up to 75% of the charge mass
volume reduction and low SO2 emission
Electric Furnace Isasmelt Furnace
Further achievements on preventing unstable slag from being produced are available within the CLEANLEAD technology. Conventional unstable sodium-based slag can be re-smelted in electric arc furnace. Tests carried out in a 80 kVA pilot unit confirm that re-smelting of soda slag in the presence of iron oxides and sand produces non-toxic stable ferrosilicate slag. In addition, some matte is generated, which reduces SO2 emissions.
way developed deals
with using the sodium sulphate slag from an Isasmelt furnace as
flux in the
rotary furnace. This slag performed as well as the currently
used sodium carbonate flux and therefore can replace it, thus reducing the operating cost.
The technological innovations described above have been integrated in CLEANLEAD
optimised smelting process, which
great flexibility and important
improvements to suit local operating requirements. The gathered
benefits of the optimised smelting processes are:
ferrosilicate slag within current and future
environmental regulations is produced, avoiding current
generation of unstable and toxic sodium-based slag. ØElimination
or substantial reduction of SO2 gas emission. ØDecreas ing
energy consumption and total operating
costs. Ø ing process performance and environmental aspects
of furnace operations.
Lead Electrowinning Pilot Cell
A novel process
under the CLEANLEAD
technology deals with the hydrometallurgical treatment of battery paste to
obtain pure Pb. This approach stands as a n
to smelting and offers zero waste and low cost sustainable
In this process, battery paste is reduced and desulphurised to render it
suitable for feeding a low energy lead electrolytic process. Reduction is
carried out by adding battery
acid together with a small amount of lead bearing sulphides such as mattes, concentrates,
fumes, etc., as reducing agents, which involve
lower costs and an extra amount of lead
eventually recovered. The desulphurisation is performed with
sodium hydroxide, which is regenerated in a subsequent step. This saves consumable
and produces valuable gypsum. Desulphurised paste is leached with sodium
hydroxide at 60 ºC, and then the pregnant solution containing dissolved lead
passes to lead electrowinning in alkaline media, having an energy requirement
of 0.5 kWh/kg Pb and current efficiencies close to 100%. The developed
electrolytic process shows important technical and environmental advantages,
lower operating cost than conventional lead smelting technology.
Vesatility of Products
As an alternative to lead electrowinning, the CLEANLEAD
also allows pure Lead Oxide production at very competitive cost, which is
suitable for new pastes manufacturing
or other industrial applications.
The CLEANLEAD Process represents a radical innovation and definitive
solution to the
current problems the secondary lead
industry is presently facing in Europe and worldwide.
The new technologies deal efficiently with all battery components, e.g.
drained acid, metallic lead
, and pastes, proposing the
best solution for
is a must for the
developed CLEANLEAD process, pursuing zero-waste emissions, getting
substantial savings in operating and environmental costs, and producing
reusable valuable products instead of toxic wastes or slags generated by
conventional smelting processes.
High quality and diversified products can be obtained, such as pure lead oxide, pure electrolytic lead, commercial gypsum, etc.
and flexibility, which can be implemented as a whole or step by step, and easy to be adapted
to local industr y
conditions and requirements.
PERSON: Mr. Carlos Frías,
TÉCNICAS REUNIDAS, S.A., R&D Division
Calle Sierra Nevada, 16 - San Fernando de Henares - 28830 Madrid (SPAIN)
Phone: 34 91 6558780; Fax: 34 91 6558789; E-mail: email@example.com