Scrap,lead

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). 

In the United States, about 40% of the lead used is recovered from scrap. There are two types of scrap lead. The term old scrap applies to metal that has already been used in some manufactured object and the used article has been recycled for resmelting. Lead in the form of pieces cut off, filings, turnings, and so forth discarded during manufacturing processes is called new scrap. Automobile batteries constitute the largest source of old scrap lead. 

WATER OR moisture AWAY FROM THE MOLD AND HOT LEAD. Water will cause the melted lead to explode. Scrounge lead from wheelwelghts at the gas station, sewer pipe joints tn houses being torn down, the lead sheath around telephone cable, and scraps of solder. Sometimes you can buy scrap lead from Junk dealers. 

Short life of car accumulators, involving their replacement and recycling of scrap-lead as a raw material. In this way developed countries are considering the scrap-lead source as lead mine , cheap to exploit and almost inexhaustible. 

The by-law of the consortium obliges anyone detaining spent lead/acid batteries (and scrap-lead) to transfer them to the consortium either directly or through... 

On the other hand scrap-lead leaves the drum and reaches a rotating sieve for washing. After that it falls onto a conveyor belt and is stockpiled. Periodically and alternatively, the slurry carrying also the active matter is drawn from the tank and sent to a couple of draining tanks, of which one is contimrally being replenished and the other depleted. Here, water drains the material and is then eliminated into a sewer, while the active mass is from time to time collected, dried and added to the one already separated by the rotating sieve. 

Another 3x10 tonnes of lead are produced from secondary sources each year, by recycling scrap lead products such as sheet, pipe and batteries. Today, in the western world, more lead is produced by recycling than by mining. More than 50% of the lead consumed in the US is in the form of batteries, and of this about 90% is reclaimed. At present, battery scrap is converted to impure lead or lead alloys by pyro-metallurgical processes employing blast, reverberatory, or rotary furnaces. The overall recovery of the metallic components of scrap in plants having both reverberatory and blast furnaces is > 95%. 

The composition of the furnace dust primarily depends on the steel grade being produced. For instance, low alloy steels will not generate emissions containing chromium or nickel, whereas stainless steel will. Another important factor is scrap quality. Melting galvanised steel scrap leads to significant emissions of zinc oxide. 

Secondary lead is primarily sourced from scrap lead-acid batteries but also processed scrap metallics such as sheet and pipe. Secondary operations are characterised by relatively small plants in comparison with primary smelters, and are sized to handle scrap availability within a local area. This is determined by the economics of scrap battery collection and transport to the secondary operation, and it follows that the largest secondary plants are located in the high vehicle density areas of the USA. 

Metallic scrap is one significant source and can be pnrchased by the smelter or refinery at prices reflecting a nominal discount to the prevailing LME price for refined lead. However, the bulk of secondary lead is derived from the processing of recycled scrap lead-acid batteries. The trade is very localised with no general standard terms and the cost to the secondary smelter often simply reflects the cost of collection of scrap batteries. 

This part of the text covers the preparation of secondary feed materials and the smelting processes used for iead extraction. This predominantly covers the treatment of scrap lead-acid batteries. 

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. 

To understand the requirements for processing scrap lead-acid batteries, as the predominant component of lead scrap, it is useful to review the operation of a battery and its construction. The lead-acid battery uses a positive electrode or plate composed of Pb02 as (he active material, and a negative electrode or plate, composed of sponge lead as the active material. The electrolyte is dilute sulfuric acid and upon discharge both active materials are converted into lead sulfate according to the reactions shown in Equations 10.1 and 10.2. This explanation of the action of the battery is referred to as the double sulfate theory . It may be a simplistic view, but broadly explains the essential principles of the operation of the battery. 

Secondary lead smelting is predominantly based on the treatment of scrap lead-acid batteries, as detailed in Chapter 10. A wide range of smelting methods are used for the treatment of secondary lead, originally based on traditional smelting methods such as the hearth and blast furnace, feeding whole batteries, but are changing under stricter environmental controls to the use of prior separation and specialised reduction in rotary furnaces or newer electrochemical techniques. 

Anodes are lifted from the cells at the end of their nominated life, which may be between six and eight days. The slime deposit is removed by brushing using steel brushes and the residual scrap lead is recycled back to anode casting. Residual lead consists of that part of the anode above solution line as well as the remaining sheet below the solution line, which is needed to structurally hold the sUme deposit. The amount of umefined lead recycled in this way is about 25 to 40 per cent of input lead. 

As an example, indicative costs are provided for the treatment of scrap lead-acid automotive batteries to produce refined lead using battery breaking and paste desulfurisation, followed by melting and reduction in a short rotary furnace, as described in Chapters 10 and 11. A typical small scale unit handling 35 000 tonnes per year of batteries is considered with a lead production of around 19 000 tonnes per year. Relevant production data is as follows ... 

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. 

The lead is supplied by the metallurgical works in the form of pigs of about 99.8 per cent purity from the melting kettle it is fed directly to the container. Scr ip lead is often added to the lead bath in order to reduce the price of the pipes. Pure lead gives aboud 2% lead dross, whereas about 8% residue have to be taken into account in scrap lead. The dross is collected and refined by chemical works. Larger quantities of scrap lead are refined in a simple manner by heating it to a temperature of about 450 to 500 °C and skimming off the dross from the surface of the metal. 

If battery trade flows are more broadly defined, they would have to include the volume of SLI batteries in vehicles which are traded internationally, together with movements of scrapped lead batteries. Taking account of these various flows, it is theoretically possible to estimate a net battery balance for each trading nation. ... 

A draft agreement for a ftilly-fledged mineral commodity agreement for lead and zinc was submitted to the Study Group for consideration in 1964, but was not adopted. The lack of support for such a move reflected three main factors the dominant role played by developed country producers in the supply of both metals the fact that lead and zinc are produced in association with each other, and with other metals like silver and copper and the importance of scrap lead supply."... 

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