Secondary Materials and Pretreatment

As indicated in Chapter 1, global lead consumption from secondary sources approached four million tonnes per year in 2005, or 60 per cent of total world consumption. Around 20 per cent of world consumption is for uses where recycling is difficult, such as for plastics stabilisers, for TV tube glass, for shot and ammunition. Of the remainder, ten per cent is used for rolled or extruded alloys and cable sheathing, which have long-term applications, and 70 per cent is used for batteries. Recyclable lead therefore is predominantly from used automotive batteries, with some from reclaimed sheet, cable sheathing and other metallic scrap. In addition there are various residues, drosses and flue dusts containing lead. 

Secondary residues are often handled by primary smelters as a supplanent to concentrate feeds. Secondary smelters accept metallic scrap, but are primarily oriented to the processing of scrap lead acid batteries, which represent more than 85 to 90 per cent of secondary smelter feed. 

Up to the 1970s the secondary industry was often small scale and localised in major population centres for ease of collection of used automotive batteries. It was also oriented to the return of the lead produced to the battery manufacturers. This was not difficult since most batteries used antimonial lead alloy for the grid material and hence the secondary smelter could recover both antimonial lead and soft lead, which could be suitably blended for return to the battery manufacturers. Since that time there have been significant changes, as follows  

There has also been a general trend to restrict the disposal of lead acid batteries in waste landfill, mandating their collection and recycling. Many countries introduced schemes for battery recycling, which included the levying of charges on new batteries to cover the costs of collection and recycling. 

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The ultimate development in the field of sample preparation is to eliminate it completely, that is, to make a chemical measurement directly without any sample pretreatment. This has been achieved with the application of chemometric near-infrared methods to direct analysis of pharmaceutical tablets and other pharmaceutical solids (74-77). Chemometrics is the use of mathematical and statistical correlation techniques to process instrumental data. Using these techniques, relatively raw analytical data can be converted to specific quantitative information. These methods have been most often used to treat near-infrared (NIR) data, but they can be applied to any instrumental measurement. Multiple linear regression or principal-component analysis is applied to direct absorbance spectra or to the mathematical derivatives of the spectra to define a calibration curve. These methods are considered secondary methods and must be calibrated using data from a primary method such as HPLC, and the calibration material must be manufactured using an equivalent process to the subject test material. However, once the calibration is done, it does not need to be repeated before each analysis. 

A 13-residue P-sheet breaker peptide (iPrP13) (Table fV) was shown to pardy reverse PrP to a PrP -like state. Mice inoculated with iPrP12-pretreated infectious material showed delayed appearance of clinical symptoms (Soto et at, 2000). The pepdde is thought to direcdy change the conformation of PrP = from a p-sheeted to a more a-helical secondary structure and therefore reduce infectivity. 

Secondary Ion Mass Spectrometry used as a solo Instrument or in concert with other methods has proven to be an excellent technique for studying the surface chemistry of adhesive bonding materials. The application of SIMS is shown in re.lation to pretreatments of metals and alloys, chemistry and structure of adhesives, and locus of failure of debonded specimens. 

Wastewater treatment systems can be classified, in addition to pretreatment, as preliminary, primary, secondary, and tertiary (advanced) treatments. Pretreatment of industrial wastewater is required to prevent adverse effects on the municipal wastewater treatment plants. Preliminary treatment is considered as any physical or chemical process that precedes primary treatment. The preliminary treatment processes may consist of influent screening and grit removal. Its function is mainly to protect subsequent treatment units and to minimize operational problems. Primary treatment is defined as the physical or chemical treatment for the removal of settleable and floatable materials. The screened, degritted raw wastewater from preliminary treatment flows to the primary clarification tanks, which are part of the primary treatment facilities. Secondary wastewater treatment is the process that uses biological and chemical treatment to accomplish substantial removal of dissolved organics and colloidal materials. The secondary treatment facilities may be comprised of biological reactor and secondary clarification basins. Tertiary (advanced) wastewater treatment is used to achieve pollutant reductions by methods other than those used in primary and secondary treatments. The objective of tertiary wastewater treatment is to improve the overall removal of suspended solids, organic matter, dissolved solids, toxic substances, and nutrients. 

In the case of pretreatment, this is due to the difference in recovery (75% for secondary effluent 50% for seawater), which results in a larger seawater pretreatment system. The capital cost for the seawater RO process is higher than for the secondary effluent RO as it is operating at a much higher pressure, lower permeate flux, lower recovery, and must be made of materials that resist corrosion in seawater. 

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