Lead-acid batteries production

Table 2. Automotive lead-acid battery production 1997 (million kWh, estimate)...

This chapter provides a review of life-cycle issues that are likely to be important for lead-acid battery production and recycling. Issues specific to VRLA technology are noted, as are generic considerations associated with other lead-acid battery... 

Lead-acid batteries, after consumer use, do not typically release aU of their lead contents into environmental dispersion channels. Instead, the lead content of much lead-acid battery production is recycled. This is not to say that the cmder forms of battery recycling are or have not been associated with waste streams, particularly at the breaking phase where lead components are first recovered for eventual secondary smelting. Unsecured disposal on land of battery acid containing lead provides not only plumes of the metal in toxic bioavailable forms but also mobility for it as the acid retards soil binding of lead. That recycling, often classified as part of scrap lead inventories, is a significant contributor to secondary lead production. As seen in various tables in Chapter 3, secondary lead production over recent decades has become a major part of total production. 

Battery manufacturers that have adopted the low sodium silicate electrolyte into their lead-acid battery production process have stated the following advantages over conventional and gel-type lead-acid batteries ... 

The electrowinning process developed by Ginatta (34) has been purchased by M.A. Industries (Atlanta, Georgia), and the process is available for licensing (qv). MA Industries have also developed a process to upgrade the polypropylene chips from the battery breaking operation to pellets for use by the plastics industry. Additionally, East Penn (Lyons Station, Pennsylvania), has developed a solvent-extraction process to purify the spent acid from lead—acid batteries and use the purified acid in battery production (35). 

Secondary lead production made up over 70% of the lead produced in the United States in 1992 vs 54% in 1980. The amount of secondary lead produced was 698 X 10 t in 1988, 888 x 10 t in 1990, and 878 x 10 t in 1992. Of the 1.2 x 10 t of lead consumed in the United States in 1992, approximately 880,000 t were produced from the recycling of lead—acid batteries and 350,000 t from primary sources. A similar trend exists worldwide. In 1992, for the first time, slightly over half (51%) of the lead produced in the world came from secondary sources. 

Silver reduces the oxygen evolution potential at the anode, which reduces the rate of corrosion and decreases lead contamination of the cathode. Lead—antimony—silver alloy anodes are used for the production of thin copper foil for use in electronics. Lead—silver (2 wt %), lead—silver (1 wt %)—tin (1 wt %), and lead—antimony (6 wt %)—silver (1—2 wt %) alloys ate used as anodes in cathodic protection of steel pipes and stmctures in fresh, brackish, or seawater. The lead dioxide layer is not only conductive, but also resists decomposition in chloride environments. Silver-free alloys rapidly become passivated and scale badly in seawater. Silver is also added to the positive grids of lead—acid batteries in small amounts (0.005—0.05 wt %) to reduce the rate of corrosion. 

Element. The process of fabricating lead—acid battery elements as depicted in Figure 4 involves numerous chemical and electrochemical reactions and several mechanical assembly operations. AH of the processes involved must be carefully controlled to ensure the quaUty and reUabiUty of the product. 

World production of lead—acid batteries in 1988, excluding the Eastern European central economy countries, has been estimated at 9.45 biUion. The automotive market was 6743 million or 211.6 million units. Industrial battery sales were 2082 million and consumer battery sales were 454 million. Motorcycle batteries accounted for an additional 170 million or 25 million units. Most batteries are produced in the United States, Western Europe, and Japan, but smaller numbers are produced worldwide. The breakdown in sales for the three production areas foUows. Automotive battery sales were 2304 million in the United States, 1805 in Western Europe, and 945 million in Japan. Industrial battery sales were 525 million in the United States, 993 million in Western Europe, and 266 million in Japan. Consumer battery sales were 104 million in the United States, 226 million in Japan, and 82 million in Western Europe. More than half of all motorcycle batteries are produced in Japan and Taiwan (1). 

The secondary production of lead begins with the recovery of old scrap from worn-out, damaged, or obsolete products and with new scrap. The chief source of old scrap is lead-acid batteries other sources include cable coverings, pipe, sheet, and other lead-bearing metals. Solder, a tin-based alloy, may be recovered from the processing of circuit boards for use as lead charge. 

Lead-acid batteries are produced using lead, sulfuric acid, additives such as antimony, and various other raw materials. Your facility s battery production capacity is 5,000 batleries per day, and the facility normally operates 24 hours per day, 300 days per year. 

PbO and Pb304 are oxides of lead that are important primary products. Under certain circumstances, PbO is also observed in lead-acid batteries (cf. Sec. 4.4.5.1). Fig. 1 shows that these oxides are only stable in a neutral or alkaline environment. Their equilibrium potentials are represented by curves C-F and their standard values are compiled in Table 3. 

In the lead-acid battery, sulfuric acid has to be considered as an additional component of the charge-discharge reactions. Its equilibrium constant influences the solubility of Pb2+ and so the potential of the positive and negative electrodes. Furthermore, basic sulfates exist as intermediate products in the pH range where Fig. 1 shows only PbO (cf. corresponding Pour-baix diagrams in Ref. [5], p. 37, or in Ref. [11] the latter is cited in Ref. [8]). Table 2 shows the various compounds. 

Electric road vehicles have been reduced to insignificance, as mentioned already by, vehicles with combustion engines. Another electric vehicle — the electrically driven submarine — presented a continuous challenge to lead-acid battery separator development since the 1930s and 1940s. The wood veneers originally used in electric vehicles proved too difficult to handle, especially if tall cells had to be manufactured. Therefore much intense effort took place to develop the first plastic separators. In this respect the microporous hard rubber separator, still available today in a more advanced version, and a micro-porous PVC separator (Porvic I) merit special mention 28]. For the latter a molten blend of PVC, plasticizer and starch was rolled into a flat product. In a lengthy pro-... 

Exports of lead metal increased from 55,500 metric tons in 1990 to 94,400 metric tons in 1991, then fell to 44,000 metric tons in 1996 and 37,400 metric tons in 1997. In 1997, the U.S. exported lead metal primarily to South Korea, Canada, United Kingdom, Malaysia, Belgium, and Taiwan. Lead waste and scrap exports, which amounted to 71,900 metric tons in 1990, rose to 104,300 metric tons in 1995, dropped to 85,300 metric tons in 1996, and rose to 88,400 metric tons in 1997. The lead content of exported scrap lead-acid batteries went from 4,800 metric tons in 1990 to 1,400 metric tons in 1995. No later export tonnage figures for scrap lead-acid batteries are available for 1996 because the data were collected by dollar value only. Most exports are in the form of lead-acid batteries or products containing either lead-acid batteries or other applications of lead (Larrabee 1998 Smith 1998). 

Although certain uses of lead preclude recycling (e g., use as a gasoline additive), lead has a higher recycling rate than any other metal (Larrabee 1998). An estimated 90-95% of the lead consumed in the United States is considered to be recyclable. In the United States, 77.1% of the lead requirements were satisfied by recycled lead products (mostly lead-acid batteries) in 1996. This compares to 69.5% in 1990 and 55.2% in 1980 (Larrabee 1997, 1998). 

Arsenic is also used in small quantities in the manufacture of lead-acid batteries (which are recycled), in the production of a few nonferrous alloys and in the electronics industry. It has been suggested that rather than importing primary arsenic for industrial uses, this could be recovered from wood waste, although the amounts required are only of the order of one to two thousand tonnes per year in Europe, and similar amounts in the USA (Lindroos, 2002). 

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