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C. Review and discussion of environmental assessment techniques, with a focus on EnTA John Hay presented an overview of environmental assessment techniques, thereby providing a context for environmental technology assessment. He noted that environmental assessments address three core values:
Environmental assessments, including environmental technology assessment, facilitate improved environmental outcomes by:
D. Economics of battery recycling Ulrich Hoffman reviewed the likely environmental impact on different economies arising from the economic effects of the Basel Ban Amendment. While not yet in force, the Amendment is being imposed voluntarily by many countries, including the Republic of the Philippines. The Amendment bans the export of hazardous wastes, including lead acid batteries and lead wastes, from OECD countries to non-OECD countries. Under prevailing conditions in the Philippines, the Basel Ban Amendment effectively encourages the importation of primary lead in order to bridge the domestic supply-demand gap because primary lead is nearly as cheap as secondary lead. A comprehensive national strategy is therefore required to reduce waste generation, enhance access to domestic sources of lead scrap and make recycling environmentally sound and economically viable and efficient. He went on to identify the elements of a national strategy that included optimizing collection, enhancing the environmental performance of the formal sector, and the downsizing and integration of the informal sector into the regulated sector. Packages of policy measures include those that involve significant government intervention with respect to collection, research and development for prolonged battery life, production of a low cost battery line and facilitating the use of environmentally sound technologies. Another package of policy measures would promote high capacity utilization of licensed recyclers through supplementary regulation and public financial support for collection, private sector investment in new technology and research and development for prolonged battery life, public financial support for easing sales conditions of an inexpensive battery line and allowing battery scrap imports by licensed secondary recyclers. Major determining factors as to which policy measures should be used are the international lead price and the foreign and domestic supplies of used lead acid batteries. E. Construction and design of the modern recyclable lead acid battery Brian Wilson described the make up and design of the modern recyclable lead
acid battery. The major components are the electrodes (typically pure lead oxide
and lead sulfate for the cathode, with the anode being a grid of metallic lead
alloy with various elemental additives that might include antimony, calcium,
arsenic, copper, tin and selenium), the electrolyte (dilute sulfuric acid), the
separators, lead terminals and the plastic or rubber casing. The typical lead
battery consists of 17% metallic lead, 50% lead oxide/sulfate, 24% electrolyte,
5% plastics and 4% (and reducing) inert residuals. F. Principles of hydro-metallurgical battery recycling Carlos Frias discussed the environmental effects of hydro-metallurgical processing of used lead acid batteries. In addition to the treatment of battery pastes, he reviewed current and best practices with respect to the treatment of the drained electrolyte, metallic grids and connectors. He noted that efficient separation of the various battery components facilitates further treatment, and that most of the negative environmental impacts arise from the composition of the battery pastes, especially the 20% sulfur content. Hydro-metallurgical contributions to lead acid battery processing include treatment of the drainage acids, battery paste desulfurisation, treatment of the pastes, recycling of baghouse fumes, ashes, slags and old slag deposits and contaminated soils, and treatment of the lead sulfide concentrates. Of all the hydro-metallurgical options for the treatment of pastes, only the PLACID process has demonstrated complete technical viability. Whilst PLACID technology can completely replace traditional pyro-metallurgical recycling, partial hydro-metallurgical recycling can complement rather than substitute conventional furnace technology. A brine/acid solution is used for lead dissolution and electrowinning. There are no liquid effluents, just inert leaching residues. All slags, ashes and drosses are recycled to the PLACID line and the acid used in the process regenerates. Sulfurous gases are eliminated and gaseous emissions are eliminated in the hydro-metallurgical process and are minimal in the combined hydro-metallurgical and traditional furnace technology. This is because the lead compound produced can be melted at low temperature. The PLINT process is advocated for the treatment of pastes, and is also appropriate for re-treating old slag deposits and contaminated soils. The process is similar to the PLACID process, but it produces a pure lead hydroxide instead of electrolytic lead. G. Principles of pyro-metallurgical battery recycling Edmundo Esguerrra, Environmental Engineer with Philippine Recyclers Inc. (PRI), described the high temperature extraction of lead from used lead acid batteries. The technology involves pre-treament (including crushing, screening and sorting), desulfurization, smelting and refining. He reviewed the various furnace configurations used in smelting lead, and the secondary lead refining process. Environmental controls, such as afterburning, the use of baghouse filtration systems, wet gas scrubbers, ventilation hoods and the treatment of wastewater were also described.
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