Furnace Metals Used Material Used CommentRotary Al, Pb, Cu, precious

metalsScrap & other secondary, blister Cu

Oxidation and reaction with substrate.

Tilting Rotary Furnace1

Al, Pb Scrap & other secondary

Minimizes salt & flux use.

Reverberatory Al, Cu, Pb and others

Scrap & other secondary, black Cu

Isasmelt2/Ausmelt3 Cu, Pb Intermediates, concs. & secondary materials.

Isasmelt and Ausmelt are same technology

QSL4 Pb Concs. & sec. materials

Kivcet Flash Furnace5

Pb, Cu Concs. & sec. materials

Blast Furnace and ISF

Pb, Pb/Zn, Cu, precious metals, high carbon ferro-Mg.

Concentrates, most secondary materials

For ferro-manganese production - only used together with energy recovery.

Outokumpu Flash Smelter6

Copper, nickel, lead Concentrates

Kaldo Furnace7 Most non-ferrous metals, including Cu & Pb

Concentrates and secondary

Oxygen rich burner system

Table 1. Primary and Secondary Lead Furnace Options

Serious and urgent consideration must be given to either reconfiguring the present operation to accommodate lead concentrate or constructing a second smelter that is designed to switch from ULAB to lead concentrate and “visa versa”. Unfortunately, the number of feasible options for smelting both primary and secondary materials is limited and summarized in Table 1.It is clear from the table that the current configuration at Hubei is not well suited to smelting primary and secondary materials. The reverberatory furnace is designed to treat

1 Dross Engineering - http://www.dross-engineering.com/lead.htm 2 Isasmelt Furnace - http://www.mimpt.com.au/isasmelt-technology.html - http://www.mimpt.com.au/downloads/isasmelt4.pdf 3 Ausmelt Technology - http://www.ausmelt.com.au/techno_furnace.html 4 BAT in German Lead and Zinc Production – French German Institute for Environmental Research, Feb. 1999 - http://www.umweltdaten.de/nfp-bat-e/zincandlead-e.pdf, pages 44, 50, 97-106, 179, 5 Kivcet Flash smelter - http://www.metsoc.org/virtualtour/processes/zinc-lead/kivcetlarge.asp 6 Outokumpu Flash Smelting - http://www.outokumpu.fi/mineralprocessing/pdf/Flash_Smelting_ENG.pdf 7 Boliden Contech - http://www.boliden.ca/Contech/contech.htm, click on “Technologies” then “Lead Smelting”.

secondary materials and despite the fact that the rotary furnace could be adapted or modified to process primary materials, it too small to be a viable option.

Alternatively, as the Company has considerable expertise in the field of electrolytic refining, consideration could be given to a hydrometallurgical process for the treatment of both primary and secondary materials. The PLACID process developed by Technicas Reunidas in Spain or a combination of the PLACID or the new PLINT8 process in conjunction with pyrometallurgy might be more appropriate because it utilizes existing pyrometallurgical equipment thereby reducing the capital cost of any investment.

Fig.5 Isasmelt and Gas Supply Buildings

One important fact to bear in mind when considering the Isasmelt option is that the ULAB/lead concentrate recycling/smelting process is enhanced when the Isasmelt furnace is operated in tandem with a second furnace dedicated to grid metallics and by-products. The reason for this is that the Isasmelt furnace is ideal for producing antimony free lead bullion from a feedstock comprising of battery paste from the breaker. Given normal operating conditions any antimony in the battery paste will be retained in the furnace slag. As the company is producing Calcium lead alloys, and the demand is likely to increase, the more antimony free furnace lead bullion produced the quicker and cheaper will be the refining stage. Accordingly, it is illogical to charge the Isasmelt with high Antimony furnace slag to recovery the metal content because the furnace will then be contaminated with Antimony and this may result in undesirable high Antimony bullion from the battery paste charges. 8 The TR PLACID and PLINT Processes– see Appendix 1 for a full explanation of the two processes used in conjunction with pyrometallurgical smelting and refining.

Before any such decisions are made it is also strongly recommended that a team of specialists from the company visit the Metal Reclamation (Industries) Sdn. Bhd (MRISB) Plant in Kuala Lumpur and look at what they have done and achieved. MRISB were in a similar position to the Jinyang Company some years ago; growing domestic demand for battery alloys, chronic shortage of domestically sourced ULAB and a ban on the import of ULAB from other countries. The management of MRISB decided to choose a plant upgrade that would enable the processing of either ULAB or lead concentrate or both. The chosen upgrade was 60,000 MT/y MIM Isasmelt and the new furnace gives the company the flexibility it needs in a tight market. Since completion of the US$ 20M modernization program in 2001, MRISB has become the largest producer of lead battery alloys in the ASEAN group of countries.

Far better to charge the high Antimonial slags to a separate furnace and dedicate the Isasmelt to battery paste.

Professional advice has already been given to you suggesting that the most effective combination would be two Isasmelt furnaces, that is, one larger than the other with the largest being used to smelt either battery paste or lead concentrate. In preference, ILMC would recommend an Isasmelt/rotary combination for two reasons. Firstly, the company already has a relatively new rotary furnace that could be used, thereby reducing the capital cost of a plant upgrade substantially. It is a small furnace, but dedicated to melting grid metallics from the battery breaker and smelting and refining by-products, it might be large enough depending on the future throughput of the plant. Secondly, a rotary furnace will enable greater smelting flexibility for by-products and any other refining drosses and agglomerated baghouse fume. It should be noted that there is no real conflict in advice, as both combinations will work. Furthermore, both the ILMC and your professional consultant have independently recommended dry desulfurization in the furnace, demonstrating a clear convergence of opinion.

Ventilation and Dust Collection

There was little or no fume present in and around the plant, and although the baghouse system was not modern, each furnace had a separate extraction and ventilation sytem and everything seemed to be perfectly adequate. The only recommendation is to place covered collection bins under the drop out valves from the baghouses to prevent dust being blown out of the collection areas into the plant and the surrounding area. In addition, each of the covers on the collection bins should have a hole in the middle. This would permit a flexible tube to be attached to the end of the drop out valve and pass directly through the hole in the cover into the collection bin. In this way, the fume drops directly into the covered bin and none is lost to the wind (fig. 6).

Fig 6. Fume collection skip with cover and a flexible tube attached to the down pipeBaghouse fume is mixed with the oxide paste from MA Breaker then charged to the furnace for lead recovery. As with all the methods of treating baghouse fume in a furnace, retention time is paramount. No mixing equipment was found and in the absence of a high

temperature furnace to make fume bricks charging the fume mixed with oxide paste to a reverberatory furnace is the best option right now. Nevertheless, it is well know that fume most of the baghouse fume dust mixed with the oxide paste will simply separate from the paste in the furnace as the charge dries out and be “sucked” back into the baghouse before the reduction process has had time to act on the material. Consideration should therefore be given to some form of agglomeration furnace to fuse the fume dust into a solid mass that would have a long retention time in the furnace.

An agglomerator furnace is usually about 2 or 3 m square. The furnace can be easily fabricated locally and needs very little maintenance (Fig. 7). The baghouse fume dust is fed from a storage hopper via a rotary non return valve into a screw conveyor. Here a small quantity of soda ash is added from a second hopper, and then the mix is dropped onto a sloping hearth that has a gas or oil fired burner pointed towards and “playing” onto the hearth. The flame of the burner is set to a “lazy” yellow flame that has a wide flame front that covers the hearth area. Under the influence of the gentle heat from the burner, the fume dust will become molten, flow down the hearth and drip off the end of the sloping hearth into a collection pot. Sometimes limestone or iron oxide flux is added to the molten fume at this stage to mix it prior to smelting in the main furnace. The appearance and consistency of the agglomerated fume dust is similar to a hard brittle yellow plastic, but this metamorphism from dust to solid will increase the residence time in the furnace, improve lead recovery and reduce by-product re-circulation, and thereby costs.

Fig. 7 Agglomerator Furnace

Alternatively, if the company decides to install an oxygen supply to enrich the main lead furnace burners an agglomerator furnace similar to the one seen at the Doe Run Buick

plant in Missouri, can also be contemplated. This furnace, designed and built by the Doe Run Company (Fig. 8), is a refractory lined dust agglomeration furnace with two oxygen enriched propane fired High Ram burners. One burner is located in the roof and the other is located in the end wall, and both are aimed directly at the feed pile. Unlike the agglomerator furnace outlined above and shown in figure 6, the furnace chamber gas temperature is maintained between 980°C and 1200°C, depending on the metallurgical components of the baghouse fume and dust.

The gas outlet duct from the furnace is refractory lined and is mounted in the center of the roof. This outlet duct is sloped at 60° to the process gas-cooling chamber, where it commingles with other process gases prior to the baghouse. The agglomerated slag is cast into a solid tapered 360 kilo block and then reduced in size (by cutting) prior to re-processing through the main lead furnace. The furnace “residence” time of the rock hard agglomerated leaded fume and dust substantially increases, and most of the lead is recovered with a pro-rata reduction in the re-circulating by-product load.

Fig. 8 Doe Run Agglomerator Furnace using Oxygen Enriched Propane Gas Burners

Refining and Casting

The refining and casting floor is labor intensive and employs the oldest technologies in the plant. The company plans to upgrade the whole of the area encompassing the refining and casting operations, and this will include the installation of automated casting machines. No final decisions have been made on the layout or the type of equipment.

The lead refining process followings traditional kettle refining methodologies to produce pure lead, and a range of lead alloys9. The manually operated equipment looks antiquated, but the Company achieves very high standards and has a Quality Control Laboratory with all the necessary instrumentation to analyze the lead ingots, and is also accredited with ISO 9001 for Quality Management.

The 25 K moulds for the ingots are arranged in the shape of a half “carousel” and filled on the floor of the building housing the Refining and Kettle floor. From a safety point of view, this arrangement is unsafe because employees are working above the molten metal and walk over and around the moulds during the casting operation as the surface of the molten lead is skimmed and the pouring spout is moved manually from one mould to the next.

The operators also use a pickaxe to “dig” ingots out of the moulds by swinging the tool at head height and bringing down the point of the pickaxe into the cast lead embedding it just enough to enable the ingot to be “levered” out of the mould. Assurances were given that this practice would cease when the automated casting machine was installed. Consideration should be given to terminating this procedure as soon as possible and a safe alternative method of removing the ingots from the moulds introduced.

Two possible options are:

Side anchors – normally used for larger ingots and 1 MT blocks, but can be adapted for the 25 k moulds (Fig. 7)

Fig. 7 Side anchors for 1 MT lead blocks Screw anchors – either a heavy iron bolt with a “pulling eye” placed in the

center of the mould or two smaller iron bolts placed at each end of the cast ingot. The ingot is removed from the mould by pulling on the “eye” with a

9 Appendix 1 – Jinyang lead alloys

Side Anchors

SideAnchors

chain and hoist and then after removing the lead ingot from the mould, the bolt is easily unscrewed from the ingot and used again. (Fig. 8)

Fig. 8 Screw Anchors

The surface quality of the ingots, apart form those with the pickaxe holes, was excellent and no inclusions were visible on any of the ingots inspected. This was quite surprising considering the simplicity of the casting operation and is a credit to the skill of the operators. The ingots stacks are bound in steel straps in 1 MT bundles and stored under cover on the site awaiting delivery to the customers.

Housekeeping

Apart from the baghouse fume dropping directly into the open storage bin beneath the rotary valves and the concrete immediately adjacent to the ULAB reception area the site was clean and tidy. The impression was not given that the Site had been cleaned specially for a visit by a representative from the ILMC, work procedures appeared to have been devised so that the minimum amount of waste and dust was generated and that any spillage or rejected material was taken to a designated place for disposal or recycling. Equipment was a clean and all unused tools stacked neatly in racks.

There were no boot cleaners at the office entrance, but as the plant was clean and not contaminated with leaded drosses, dust and charge materials, the “ritual” cleaning of the boots prior to entry into a “clean” area is probably deemed unnecessary. The inside of the office area was spotless, clean and tidy.

The only recommendation to make would be to clearly mark in yellow paint all the walkways around the plant and especially in the process areas. These designated walkways should always remain clear of any equipment or obstruction of any kind so that in the event of any emergency there is an unimpeded exit route for employees and ingress for the emergency services if they need access to the facility.

The Political and Legislative Situation for Secondary Lead Smelters in China

On August 3, 2002 the Chinese Ministry of Foreign Trade and Economic Cooperation, the Chinese General Administration for Customs and the State Environmental Protection Administration issued a joint statement announcing an import ban would come into force on August 15 for all the items listed in the fourth and the fifth lists of “Banned Imports.” The Lists were issued in accordance with the Regulations for the Administration of Imports and Exports, the Law on the Prevention and Control of Environmental Pollution by Solid Waste and the Notice on the Importation of Waste. Imports banned under the “Fourth List” include; slag, dross and other similar industrial waste; industrial ash and other waste materials containing lead, scrap batteries and so on.

The ban was enforced immediately and the next month on September 14, Taiwanese coast guards seized10 four people and a fishing boat attempting to smuggle about 30 MT of ULAB from Taiwan to the Chinese mainland for a fee of nearly US$ 1,800. It is a certainty that the Chinese and Taiwanese Coast Guards and Environmental Agencies were aware of the activities of the smugglers and that such an illegal trade in ULAB is not uncommon. Indeed, according to reports from the Environmental Protection Agency11 in Taiwan about 200 MT of ULAB are being smuggled annually to the mainland. Taiwan in a good source of ULAB with 6.6 million cars and 10.3 million motor scooters and it is estimated that there are about 50,000 MT of ULAB to be recycled annually, but the rate of collection and recovery at the one licensed recycler in Taiwan is only about 60%. It is also a certainty that the smuggled goods were destined for an unlicensed “backyard” recycler12. Such illegal activities might also have had a significant influence on the views of the Chinese government when they were considering whether to ban the import of ULAB.

Some Chinese officials I met at the Non Ferrous Metals Recycling Seminar in Ningbo mistakenly believe that the import ban on used lead acid batteries was passed into law in order to comply with the Basel Convention, of which China is a Party. How representative their misguided views are of the senior members of the legislature is impossible to determine on this visit, but it was disturbing that this was a viewpoint held by anyone in the government.

Whatever the reason for imposing the ban on the import of ULAB is unclear. Maybe the government thought that the batteries would be recycled in an environmentally unsound manner by the smaller recyclers or perhaps they thought that the ban was necessary to comply with an international convention. In any event, the reason is now somewhat academic. It is most unlikely that the government will lift the ban in the near future and so the Chinese secondary lead industry will be, and in some cases are already facing, a chronic shortage of ULAB at time when lead demand is at its highest and increasing. For some years, a similar situation has existed in the Russian Federation and domestic prices for ULAB are now about US$ 100 per MT above the price paid on the international 10 Clari News, Sunday, 14-Sep-2003 12:41AM PDT, Copyright 2003 by Agence France-Presse, http://quickstart.clari.net/qs_se/webnews/wed/ay/Qtaiwan-china-smuggling.RKJ8_DSE.html 11 Batteries Digest, September 3 2003 - http://www.batteriesdigest.com/lead_acid_business.htm 12 Taiwan News, September 17 2003 - http://www.etaiwannews.com/Taiwan/2003/09/17/1063762076.htm

market. Understandably, the Russian secondary lead industry is in a very tight financial situation. The Chinese Secondary Lead Industry is not in the same position at present, but unless there is a clear strategy that will enable the recyclers to overcome the ULAB shortage and meet sales demands it is likely that many of the smaller businesses will be bankrupt is a couple of years.

The Management at the Jinyang Metallurgical Company is well aware of the future prospects for the supplies of domestically sourced ULAB and have a three-fold strategy:

Increase the number of domestic ULAB collected and delivered to the plant. Develop contingency plans to import and treat lead concentrates. Lobby the appropriate national and local government environmental agencies

to promote the closure of environmentally unsound recyclers.

In order to overcome the ban on the import of ULAB and meet the domestic demand the Jiangsu Chunxing Group, China's largest lead scrap recycling company, has gone to extraordinary lengths as part of their strategy. Chunxing is not only sourcing lead scrap from the domestic market for its smelters in China, but it has also established a lead recycling company in Thailand13, which is primarily engaged in collecting used batteries from the Southeast Asian market, recovering the lead and shipping it to China.

The Chinese Non-ferrous Metals Industry Association has also been trying to help the industry and persistent lobbying of the Government paid dividends in 2001. The State Economic and Trade Commission (SETC) drafted a Tenth Five-Year (2001-2005) Plan for the Utilization of Recyclable Resources in accordance with the State Council's Tenth Five-Year Plan for National Economic and Social Development. Under the SETC's plan, China would strive to recover US$ 6.64 B worth of recyclables, including 2m MT of non-ferrous metal from scrap. The government states that it is committed to form a group of large non-ferrous metal recycling centers comprising of companies engaged in non-ferrous metal scrap collection, treatment and recovery. The plan also includes the formation of non-ferrous metal scrap distribution and trading networks to integrate scrap collection, processing and recovery across the country.

One of the first outcomes of the SETC task force was to prioritize the most urgent environmental needs that can be improved by the recycling of domestic resources. The SETC chose ten cities, five rivers and three lakes that are shown on Map 1. The SETC is now drafting regulations on the collection and recovery of recyclables in a bid to standardize the operations of those companies engaged in the recycling of scrap material. Furthermore, it is also drafting a set of guidelines on the recycling of used domestic electrical appliances, used wet and dry cell batteries, and used electronic devices such as computers and mobile phones.

13 China’s Metal Regeneration Netork – Resource 2003 - http://www.resource.com.cn/english/magazine/english/e_first_15.htm

Map 1.This map shows the targeted ten cities, five rivers and three lakes.

In an effort to promote recycling the central Chinese government has recently exempted some companies in or close to the targeted ten cities that are engaged in secondary metals from VAT. This exemption does not include Jinyang Metals because there are no cities close to Shihua on the list. There are also plans to increase the level and extent of fiscal and credit support for companies involved in the recycling of scrap, including non-ferrous metals. It has also decided to help leading domestic companies in the resource recycling sector to raise funds through listing on the stock market and to provide subsidies to support technical upgrades and the application of information technology by these companies.

The initial effort by the SETC is to target the10 major cities engaged in recycling, but this approach will leave companies such as Jinyang without the opportunity to attract financial assistance and so some thought needs to be given to how such support from the SETC might be forthcoming at the Jinyang plant. Accordingly it is strongly recommended that the Jinyang Company makes representation to the Government, as a responsible and environmentally friendly recycler engaged in promoting the collection and recovery of domestically sourced ULAB in order to apply for and obtain exemption from VAT and obtain fiscal assistance to upgrade the plant. One idea that could result in a favorable reply from the Government would be to extend the ULAB collection scheme into one or two of the 10 cities on the list and apply for financial aid on the basis that a known environmental threat is being removed and a valuable resource recovered in line with the Government’s own plans.

The strategy proposed by the Jinyang management to tackle the challenges ahead is the right approach, but much work needs to be done to increase the ULAB collection network and the Government Environmental Agencies appear to be reluctant or slow in implementing the official government policy in Hubei province, that is to purge the county of unsound ULAB recyclers.

At the Seminar in Ningbo Mr. Li Fuyuan’s presentation to the main plenary session implored the Government to take immediate and firm action against the small backyard recyclers and close them down, in order to:

Stop the environmental damage resulting from their recycling activities Eliminate unhealthy occupational and population exposure from lead fumes/dust Increase the number of ULAB available to the environmentally sound recyclers

Regrettably, none of the Chinese Government representatives present at the Seminar responded with a commitment to expedite the official policy with immediate effect.

The national and local municipal Chinese government agencies support recycling and in many of the new enterprise zones provide a range of financial incentives for new companies entering the recycling business for the first time. It is a paradox therefore to discover that the Chinese government collects Value Added Tax (VAT) at the rate of 10% from the secondary lead companies when they purchase ULAB. Initially introduced in 1993 at the rate of 17%, the Government reduced the tax on ULAB to 10% in May 2001 after lobbying from the industry. Nevertheless, this tax remains a marked disincentive to the recycling of ULAB. Furthermore, it is most likely that the tax is only paid by the licensed and environmentally sound recycling companies and ignored by the “backyard” recyclers. No other country applies VAT in this way to a hazardous waste when it is destined for recovery. This tax law therefore places the Chinese secondary lead industry at a distinct disadvantage against the primary lead producers because there is no VAT charged on raw materials such as lead concentrate.

It is recommended that, as a responsible and environmentally friendly recycler engaged in promoting the collection and recovery of domestically sourced ULAB, the management of the Jinyang Company makes representation to the Government in order to apply for, and obtain exemption from VAT. The case for exemption would be strengthened if a holding or collection center for ULAB could be established in an industrial zone that attracts financial relief.

In addition, there appears to be a number of tax concessions14 that might be pertinent to the Jinyang recycling operation:

Income tax preference: Businesses that use waste water, gas or residues in the production process may apply to waive or reduce income tax for 5 years.

Appreciation tax preference: Tax collection offices can reduce or waive the appreciation tax for those enterprises that use waste or retrieve materials from

14 http://www.chinacp.com/newcn/training/page22.htm

waste. Presumably, this concession will include ULAB as it is classified under the Basel Convention as a hazardous waste and China is a Party to the Convention15.

Construction tax preference: For pollution treatment construction projects, enterprises may apply for preferential loans and waive the construction tax.

Article 2 of the PRC’s promotion laws for “Small and Medium” (sized) enterprises 16, indicates that waste treatment businesses may be eligible for special development support from the government’s National technical innovation fund for environmental protection projects.

The conclusion is that the Chinese Government clearly recognizes that fiscal policy17 is a most effective tool in promoting cleaner production and recycling. However, the exact application of any Special Technological Development Funds that have been set aside by the fiscal management departments of the Chinese State Council for use by the localPeoples’ governments at county level are unclear at this stage. In paragraph six of the notes it states that expenses incurred for cleaner production auditing and training may be booked as enterprise operating costs, so I trust that the ILMC costs and any other similar expenditure can be offset as an environmental expense.

Brian Wilson, January 2004

15 http://www.chinacp.com/newcn/training/page64.htm16 http://www.chinacp.com/newcn/training/page63.htm17 http://www.chinacp.com/newcn/training/page21.htm

Appendix 1JINYANG LEAD ALLOYS

Lead-Calcium Alloy

Usually applied as the grid alloy in sealed storage battery of maintenance-free,

COMPOSITION_(%)LEAD-CALCIUM ALLOY

Pb Ca Al Sn Pb Ca Al Pb CaPb To 100% To 100% To 100%Ca 0.06-0.20 0.8-1.3 1.0-2.0Al 0.01-0.06 0.1-0.3 —Sn 0.1-3 — —

Lead Antimonial alloy

Storage batteries, terminals, cable sheathing, die-casting, lead parts and chemicals.

LEAD ANTIMONY

ALLOY

COMPOSITION (%) IMPURITY ≤ (%)

Pb Sb As Cu Sn Se Ag Bi Fe Zn Amount

MFPbSb1 To 100%

1.60-2.2

0.10-0.26

0.02-0.06

0.05-0.2

0.01-0.05 0.01 0.02 0.005 0.003 0.05

MFPbSb2 To 100%

2.3-3.5

0.1-0.3

0.02-0.08

0.1-0.25

0.01-0.05 0.01 0.03 0.005 0.003 0.10

No.COMPOSITION(%) IMPURITY ≤ (%)Pb Sb Cu Sn Zn Bi Fe Ag Co Te Amount

PbSbCu To 100% 0.4-0.80.4-

0.8 <0.01 0.002 0.020 0.020 0.003 0.005 0.005 0.1

PbSbSn To 100%

0.015-0.30 <0.01 0.4-

0.5 0.002 0.020 0.002 0.003 0.005 0.005 0.1

Lead Cadmium Alloy

Used for the grid alloy of deep discharge lead acid traction batteries.

No. COMPOSITION(%)

Lead Cadmium Alloy

Pb Cd Sb Snrest 1.0-3.0 1.0-2.0 0.05-0.5

NEW CLEAN TECHNOLOGIES TO IMPROVE Appendix 2LEAD-ACID BATTERY RECYCLING

C. Frías, M. García and G. DíazTécnicas Reunidas S.A. (R & D Center)Sierra Nevada 16, 28830 San Fernando de HenaresMadrid, Spain

ABSTRACT

Advances in hydrometallurgy promoted by Técnicas Reunidas are providing an increasingly simple and clean means for controlling the entire lead recycling chain. Used in parallel with pyrometallurgy, these processes allow furnace temperatures to be reduced to the minimum, fumes and atmospheric pollution are minimized, furnace slag are digested, and residues (mainly gypsum) are non-toxic and convertible into marketable products. In addition, the global economy of the process is substantially improved by reducing operating costs, increasing lead recovery above 99% and obtaining a 99.99% pure lead product. These new PLACID and PLINT processes provide the cleanest and healthiest practicable means for recycling lead from used lead acid batteries (ULAB).

INTRODUCTION

This paper describes advances in PLACID and PLINT technologies that seem to be opportune for secondary lead industries in general. They have all been identified by recent and current work in the Research and Development Center of Técnicas Reunidas S.A. (TR) at San Fernando de Henares near Madrid in Spain.

As is usual in hydrometallurgy, lead is extracted with the PLACID process by electrowin-ning. While electrowinning is generally acceptable for the extraction of valuable metals, the high capital cost of the electrolytic system was perceived to be disadvantageous to established smelters when compared with the current (and possibly the future) market price of lead. Electrowinning is a better option for plants producing more than about 20,000 tonnes a year of electrolytic lead. However, one smelter, who had witnessed the operation of the PLACID pilot plant at TR’s R & D Center in Madrid, suggested that it might be possible to process the electrolyte to precipitate a pure lead compound that could be fed into a furnace for decomposition or reduction. TR has since worked on this concept for three years, leading to the definition of the PLINT (PLacid INTermediate) process described below.

The confidence engendered by this success has caused TR to review its conception of the scope of hydrometallurgy for lead processing. No longer is the aim to promote a best hydrometallurgical process, as measured against conventional standards, but to design processes that best take account of the constraints within which users operate.

To complete this presentation, economics of a selected base case are discussed and results and conclusions are included.

OBJECTIVES

Existing battery recycling technologies have inherent deficiencies that need to be upgraded to meet the most restrictive environmental regulations and to attain a sustainable growth model for the secondary lead industry in the new millennium. Most of the relevant shortcomings of current technologies are as follows:

Many technological problems are associated with the usual pyrometallurgical processing of the lead oxide and sulfate battery paste. The sulfate produces sulfurous gases that require costly containment and neutralization processes. The smelting of the battery paste generates lead fume that needs to be captured by using large electrolytic precipitators or bag filters.

Conventional techniques for battery paste desulfurization using either sodium hydroxide or sodium carbonate are expensive, and produce large volumes of undesirable sodium sulfate solution, which very frequently is a waste that is difficult to process and dispose of.

The addition of sodium hydroxide and sodium nitrate to refining kettles is a common practice during the refining process for 9997 or 9999 lead. This methodology generates large amounts of dross containing soluble sodium salts.

Sodium carbonate is a common flux for lead smelting, but it produces a leachable solid sodium based residue (slag) that without further treatment to render it inert, will be classified as a hazardous toxic waste and either difficult or expensive to dispose of safely.

Lead recovery by smelting battery paste requires high temperature (1,100ºC or above) and the addition of fluxing agents to achieve the decomposition of the lead sulfate. The drawback with these operating conditions is easily understood, that is, high energy consumption, rapid refractory wear and long tapping times. Indeed, the smelting cycle is substantially simplified when sulfate free lead oxide waste is treated.

The proposed new processes are designed to deal with all the above mentioned deficiencies in a reasonable and efficient way with the following objectives; that the:

PLACID and PLINT processes will complement and improve existing battery recycling facilities, but not replace them.

Grid metallics, lugs, bridges and terminals from the used batteries together with other metallic lead scrap would be treated by conventional furnace melting processes, while battery paste would be treated by hydrometallurgical processing. In this way, sulfurous gas emissions and lead fumes would be minimized and possibly eliminated.

Paste desulfurization step is not required. Instead, the lead sulfate is dissolved in brine and removed in the form of gypsum. Gypsum is an inert residue and can be converted into a commercial by-product.

Pure lead (9999) is produced when PLACID or PLINT technologies are applied. Conventional lead refining in kettles is not needed. The production of sodium based drosses and sodium based leachable slags is avoided.

The small amounts of fume, drosses and residues produced are sent to the hydrometallurgical stream for recovery. This means that at the end of the recovery cycle no toxic solid residue or hazardous waste is generated by the PLINT process when the pyrometallurgical and hydrometallurgical streams are utilized in a complementary manner.

Both processes run in a closed brine circuit. If necessary, the water balance can be controlled by the inclusion of an evaporator, and in this way, there is no effluent discharge to the environment.

When PLACID or PLINT processes are used in parallel in a lead smelting plant, both pure lead and lead bullion are produced. Lead bullion would be converted to alloys suitable for battery grids or other metallic battery components, while the pure lead would be ideal for battery paste production. In this way, the lead recycling loop would be closed in an effective manner that is consistent with a sustainable growth model that minimizes the need for primary lead.

One other important advantage of obtaining pure lead would be the manufacture of the new generation of longer life batteries, thereby significantly reducing the annual recycling tonnage of used lead acid batteries. For example, by increasing the average service life of a battery in Europe by just one year, the annual tonnage of recycled batteries would be reduced by approximately 20%, which would result positive effects on the environment through energy savings and improved sustainability.

ELEMENTS OF PROCESS DESIGN

The proposed new process designs are conceptually very simple, easy to understand and very efficient from a chemical and energy perspective. The processes include a series of properly coordinated unit steps. The description of each individual stage is as follows:

Hydrometallurgy and Pyrometallurgy

In advocating hydrometallurgy as its specialty, TR is not contemptuous of the pyrometallurgical processing of materials in furnaces, the advantages of which are fully recognized, but hydrometallurgy is cleaner, more precise, and easier to control when treating battery paste, lead fume and by-product drosses, etc.

Pyrometallurgy is ideally suited to processing metallic lead components, but presents many disadvantages when applied to the treatment of battery paste. Hydrometallurgy makes the treatment of battery paste much easier because hydrometallurgical processes are intrinsically cleaner. Furthermore, in combined cycle plants they can be used to reduce furnace temperatures, thereby reducing energy demands and the environmental impact of smelting whilst increasing the productivity of the existing pyrometallurgical plant.

It should be noted that aim of PLACID and PLINT technologies is to complement existing used lead acid battery recycling plants, making the best use of the synergies to complement both the “pyro” and “hydro” process streams.

Leaching

This is the initial step in which all accessible soluble lead in the feedstock is selectively dissolved. Feed materials to the hydrometallurgical processes are variable and include battery paste (the principal feed material), lead fume, drosses and slags. In addition, a small proportion of lead sulfide concentrate can be added to the feedstock. The processes can also treat old slag deposits and lead contaminated soils.

Lead dissolution efficiency is very high in these processes. In a PLACID-pyrometallurgical or PLINT-pyrometallurgical combined process, the measured lead extraction rate was 99.5% overall because the leaching process extracted available lead from process by-products and furnace residues.

The composition of the leachate is dilute hydrochloric acid in brine solution, which has the ability to dissolve lead oxides and lead sulfate in an efficient manner. In the two final campaigns of the PLACID pilot plant operation, leaching efficiency from representative battery paste/fume mixtures was 99.4 to 99.7% after treating over 15 MT of feed materials.

Main reactions involved are:

PbO + 2 HCl + 2 NaCl PbCl4Na2 + H2O (1)

Pb + PbO2 + 4 HCl + 4 NaCl 2 PbCl4Na2 + 2 H2O (2)

PbS + 4 PbO2 + 8 HCl + 12 NaCl 5 PbCl4Na2 + Na2SO4 + 4 H2O (3)

PbSO4 + 4 NaCl PbCl4Na2 + Na2SO4 (4)

Na2SO4 + 2 HCl + Ca(OH)2 CaSO4 + 2 NaCl + 2 H2O (5)

In the case of the PLACID process, hydrochloric acid is regenerated in the electrolytic cells, so lime is the only consumable. When the PLINT process is applied, an acid make-up addition is necessary, so sulfuric acid can replace hydrochloric acid because of its lower cost.

Sulfate Removal

Pre-treatment desulfurization of the battery paste is unnecessary thereby avoiding the generation of any undesirable sodium sulfate salt solution. Indeed, the paste from the battery breaker is fed directly to the hydrometallurgical processes, eliminating the dewatering process.

In the case of ULAB where sulfur is present in the lead sulfate, the preference is for a reaction with lime (about the cheapest material suitable for this purpose) to form gypsum, which is then removed by filtration.

TR has developed techniques whereby pure gypsum can be produced in any of its three morphologies (hydrated, hemi-hydrated {plaster of Paris} and anhydrous) to suit market demands. Therefore, the gypsum residue can be converted to a range of saleable products, provided the market is viable. However, the real benefit in this process is that there is no hazardous waste residue to dispose of.

Purification

The lead purification technique is very simple and involves injecting lead powder into the leachate or electrolyte to enable an electrochemical reduction of those metal impurities more “noble” than lead to take place. The purification reaction is:

MeCln + n/2 Pb0 n/2 PbCl2 + Me0 (6)

“Me” means any metallic impurity such as Cu, Bi, Sn, Ag, As, Sb...

The leachate is then filtered to remove the cement together with the impurities. The efficiency of this process is good enough to produce a pure electrolyte that ensures 9999 lead is the final product. Of course, the concentration of impurities in the electrolyte does not translate directly to the concentration of impurities in the lead because the electrode deposition favors lead preferentially over the other impurities.

The metallic lead content of the cement is over 90%, so the cement can be either returned to the furnace and recycled or absorbed into a secondary lead alloy or any other commercial grade of lead in the factory.

Lead Extraction Steps

Electro winning

The PLACID electrolytic cell is the core of this technology. The electrolyte for the two electrodes, the anode and the cathode, are different and are separated by a membrane that is permeable only by proton ions (H+). On the cathode, lead chloride is stripped of its lead atom, leaving two chloride atoms that are negatively charged. These negatively charged chloride atoms combine with protons passing through the membrane from the anode to reform hydrochloric acid that is returned to the leaching bath for reuse.

The main electrochemical reactions are as follows:

Cathodic: PbCl2 + 2 e- Pbo + 2 Cl- (7)

Anodic: H2O - 2 e- 2H+ + ½ O2 (8)

GLOBAL: PbCl2 + H2O Pbo + 2 HCl + ½ O2 (9)

The design of this cell is unusual because, instead of depositing lead onto metal plates, as in a conventional cell, the electrolysis deposits lead as dendrites or a spongy form of lead, which is subsequently shaken off and collected on a conveyor belt. Immediately after leaving the electrolyte, the dendrites are pressed to remove the liquid and to form platelets of pure lead that can then be conveyed to a kettle for casting into ingots.

There is no special value in the conventional practice of depositing the lead onto the plates because the electrolytic process must be interrupted periodically while the plates are replaced, and there is no electrolytic application for lead that will deposit the metal in the form of discrete thin flat plates.

Conversely, there are important cost and operational advantages in depositing the lead as dendrites or the spongy form, because the current (amps) can then be increased by a factor of between 4 and 10, and in so doing reduce the number of electrolytic cells required for a given throughput of finished lead. Furthermore, the whole of the extraction process can be run continuously and no manual labor is needed for cathode stripping and replacement.

Electrowinning is a capital-intensive process mainly because of the electrical transformers and rectifiers needed, and despite the fact that direct operating costs are lower than for pyrometallurgical extraction processes, the amortization costs are significant. Accordingly, electrowinning is most advantageous for large plants.

It is strongly recommended that advantage be taken of the potential cost reductions made possible by combining pyro and hydrometallurgy in the recycling plant. For example, electricity would be used for electrowinning and the electric motors, then the waste heat from the motors can be used to maintain leachate temperatures at the appropriate levels (typically about 80ºC) and for drying and evaporation where necessary.

Pure Lead Oxide Smelting

In the case of the PLINT process, a pure lead hydroxide (oxide) or lead carbonate concentrate is produced from the products of the cementation purification process.

Various reagents or a combination can be used, depending on local prices, availability and any process constraints.

PbCl4Na2 + Ca(OH)2 Pb(OH)2 + 2 NaCl + CaCl2 (10)

PbCl4Na2 + 2 NaOH Pb(OH)2 + 4 NaCl (11)

PbCl4Na2 + Na2CO3 PbCO3 + 4 NaCl (12)

This concentrate should be sent to a low temperature furnace or a melting kettle because pyrometallurgical treatment of this lead concentrate is quite simple and efficient, even at a low temperature, and only a small addition of reducing agent is required. Furnace cycle times are substantially reduced and should leave spare capacity to facilitate an increase in production.

PLACID AND PLINT PROCESSES

The PLACID Process

Much about this process has already been described in previous sections. The conceptual block diagram is shown in Figure 1.

Figure 1 – PLACID Process. Conceptual Block Diagram

The leachate is dilute acid in brine, and the desulfurization sequence is quite interesting. The lead sulfate reacts with the salt to form lead chloride and sodium sulfate, and the sodium sulfate then reacts with the hydrochloric acid and lime to yield gypsum, at the same time reforming the salt ready for reuse in the leachate. The hydrochloric acid is regenerated in the electrowinning section so the only consumable is the lime.

Different feed materials would be suitable for this process besides battery pastes, e.g. lead fume, drosses and slags, even a small fraction of lead sulfide concentrate.

Pilot plant development, in the laboratories of the R & D Center in Madrid, was carried out over several campaigns (above 1,000 hours total operation), during which 10 MT of pure electrolytic lead was produced. Energy consumption was 0.9 kWh/kg Pb. Representative samples of electrolytic lead gave above 99.99% Pb, containing 3 ppm Cu, 6 ppm Sb, 2 ppm As, 1 ppm Sn, 2 ppm Bi. The figures for purity would most likely improve in a continuous industrial plant.

The PLACID process would be perfectly integrated if it were used in parallel with a conventional pyrometallurgical smelter. In this way, any lead fume, drosses and slags from the pyrometallurgical stream can be passed to the leaching bath in PLACID stream, and the cement from the purification step in the hydrometallurgical process can be fed into the furnace. Important gains can be made in terms of environmental performance, process efficiency, product quality and economics.

The PLINT Process

A conceptual block diagram is shown in Figure 2. As can be seen by comparison of both PLACID and PLINT block diagrams, the only difference in principle is in the substitution of a precipitation step for electrowinning. In the treatment kettle, the lead hydroxide product is first decomposed and then reacted with hard coal to obtain pure lead. All that takes place at a temperature much lower than is required by current smelting processes.

Figure 2 – PLINT Process. Conceptual Block Diagram

Because the leaching and purification processes are unchanged, the leaching efficiency of this process and the purity of the lead produced should be the same as in the PLACID process.

The PLINT process needs a top-up addition of acid, so sulfuric acid can replace hydrochloric acid because it is a lower cost and the acid is converted to inert gypsum.

Obviously, it would be possible to integrate a PLINT process stream with a pyrometallurgical process, creating a system similar to that in the PLACID-pyrometallurgical process, but to maintain the division between 9999 lead and the furnace recycled lead it is necessary to have dedicated kettles and/or furnaces.

Development of these new PLACID and PLINT processes has progressed to the stage where a demonstration plant is needed.

ECONOMIC EVALUATION

PLACID Process

Selected Base Case for final feasibility study included the following conditions:

The new PLACID plant would be annexed to an existing pyrometallurgical battery recycling plant. Global lead recovery of the combined PLACID-Pyrometallurgical plant would be above 99.5%.

Lead production would be 20,000 MT/y of electrolytic lead at 99.99% purity. Feed materials would be 27,500 MT/y of battery paste and 2,500 MT/y fume and slag.

The energy consumption has been optimized. After a detailed study about electrical cost optimization, it was decided to implement a co-generation energy plant with natural gas to supply both the electricity and heat for the process. This is a very attractive option, reducing substantially the operating costs.

The basic engineering of the base case has been developed in detail including process and flow diagrams, and material and energy balances. Operating costs were estimated from the previous information. The main consumables are shown in Table I and the highest cost is to the natural gas for the co-generation plant.

Concept ValueLime kg/t PbSodium Hydrosulfide, kg/t PbProcess Water, m3/t PbNatural Gas, Mcal/t Pb

143 1.5 2.21,625

Table I. PLACID Process Consumption

An operating cost breakdown at current prices in Spain is depicted in Table II in US$ at the prevailing exchange rate, that is, 170 PTA per USD. A 10% contingency factor has been allowed. Residue disposal cost has been included, if gypsum was not sold; obviously this would be the worst scenario.

Concept US$/MT PbConsumableReagentsResidue disposalLabourMaintenanceContingency

30.8 9.2 20.0 36.0 16.3 12.0

TOTAL 124.3

Table II. PLACID Operating Cost Breakdown

The estimated total investment cost, based on sound engineering standards with a +25% contingency factor, is 19.0 million US$, including the co-generation plant investment. The high contingency factor makes this study a conservative estimate.

PLINT Process

A similar Base Case has been selected for the PLINT process, according to the following:

The new PLINT plant would be annexed to an existing pyrometallurgical battery recycling plant. Global lead recovery of the combined PLINT-Pyrometallugical plant would be above 99.5%.

Production would be about 23,000 MT/y lead concentrate (oxide or carbonate), containing 20,000 MT/y lead at 9999 purity. Feed materials would be 27,500 MT/y battery paste and 2,500 MT/y fume and slag.

In a similar approach to PLACID, the basic engineering of the PLINT Base Case has been developed in detail. Operating costs were estimated based on material and energy balances.

Main consumables are presented in Table III.

Concept ValueLime kg/t PbSulfuric Acid, kg/t PbLead Powder, kg/t PbProcess Water, m3/t PbElectricity, MWh/t Pb

520320 40 1.5 0.1

Table III. PLINT Process Consumption

Operating costs are presented in Table IV in US$ at the prevailing exchange rate, that is, 170 PTA per US$. A 10% contingency factor has been allowed. The higher costs correspond to the consumption of make-up reagents. Residue disposal costs have been included on the assumption that gypsum was not sold and, obviously, this would be the worst scenario. Low temperature smelting costs are not included in this estimation.

Concept US$/MT PbConsumableReagentsResidue disposalLaborMaintenanceContingency

32.1 40.2 20.0 20.5 9.5 13.0

TOTAL 135.3

Table IV. PLINT Operating Cost Break Down

The estimated total investment cost, based on sound engineering standards and with a +25% contingency factor, is 7.1 million US$. The high contingency factor makes this a conservative study.

Profitability

Based on the above operating and investment costs, several DCF (discount cash flow) calculations have been carried out.

IRR (internal rate of return) in the range of 16% to 28% has been calculated, which indicates that both PLACID and PLINT processes are economically very attractive.

CONCLUSIONS

When PLACID or PLINT hydrometallurgical processes are operated in parallel with any existing pyrometallurgical battery recycling plant, the environmental, technical and economic prospects of the integrated facility are substantially improved.

The proposed new processes are simple, efficient, very flexible and profitable, which makes them ideal for adaptation to the customer’s needs and local requirements.

The final evaluation study for both PLACID and PLINT processes applied to a selected Base Case producing 20,000 MT/y 9999 lead presents a very satisfactory result, which will justify their existence in a short time period. The availability of this technology has opened a window of opportunity for the secondary lead industry, and inquiries are invited.

ACKNOWLEDGEMENTS

The European organizations that have developed the PLACID process into the Brite-Euram Program show their gratitude to the European Community for its encouragement, support and partial funding of the project.

REFERENCES

“Proceso PLACID: Recuperación del Plomo de Pastas de Plomo”, Internal Report No. ITR/P4618/005/1988.

“Proyecto de Planta de Producción de 25.000 t/a de Plomo por el Proceso LEADCLOR”, Internal Reports No. ITR/P4628/029/1988 and ITR/P4650/017/1991.

D. Martín and G. Díaz, "Hydrometallurgical Treatment of Lead Secondaries and/or Low Grade Concentrates; The PLACID and the LEADCLOR Processes", Conference organised by ILZSG on Recycling Lead and Zinc-The Challenge of the 1990's, Rome, Italy, 1991, 315-336.

R. D. Prengaman, “Recovering Lead from Batteries”, Journal of Metals, Vol. 47, 1995, 31-33.

G. Díaz, “Lead Recycling”, Letter Journal of Metals, June 1995, 3-4.

G. Díaz, C. Frías, L.M. Abrantes, A. Aldaz, K. van Deelen, and R. Couchinho, “Lead-Acid Battery Recycling by the PLACID Process - A Global Approach”, TMS Third International Symposium on the Recycling of Metals and Materials, Point Clear, Alabama, 1995, 843-856.

G. Díaz and D. Andrews, “Placid - A Clean Process for Recycling Lead from Batteries”, Journal of Metals, Vol. 48, 1996, 29-31.

G. Díaz and D. Andrews, “Placid Lead for Batteries”, Batteries International, April 1996, 73-74.

C. Frías, M.A. García and G. Díaz, "Industrial Size Placid Electrowinning Cell", TMS Annual Meeting at Orlando, Florida, USA, Aqueous Electrotechnologies: Progress in Theory and Practice, D.B. Dreisinger Ed., 1997, 101-113.