Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Lead production cupellation

Lastly, When the block copper is very rich, the process is commenced by subjecting it to a first liquation with workable lead, the products of which are a rich lead for cupelling, and a middling rich black copper the latter is then submitted to a second liquation with poor lead, which yields cupreous residues very poor in silver, to be treated for rosette copper, and moderately... [Pg.856]

Silver is extracted from sulfide bearing ores of lead and copper. To be viable, the silver content should be in the order of 0.033%. During the production of pure lead, all the silver present in the ore, will have dissolved in the lead. The cupellation process was used to recover the silver from the lead. The silver-lead alloy was heated in hearths with bone ash to a temperature of 1000°C (melting point silver 960°C) and air blown over the surface. The lead, together with any other base metal, was oxidised while the silver remained unaffected. The oxidised lead (PbO - litharge) was skimmed off and a small button of metallic silver was left in the hearth. [Pg.128]

Figure 1. Anthropogenic production of lead over time [(a), logarithmic plot] is reflected in deposition of lead in Greenland ice ib), suggesting that lead pollution is a global issue. Large increases in lead production occurred with the discovery of cupellation around 5000 years ago, when silver began to be used in coins 2700 years ago, and during the Industrial Revolution. [Reprinted with permission from S. Hong, J.-P. Candelone, C. C. Patterson, and C. F. Boutron, Science, 265, 1841-1843 (1994). Copyright 1994 American Association for the Advancement of Science.]... Figure 1. Anthropogenic production of lead over time [(a), logarithmic plot] is reflected in deposition of lead in Greenland ice ib), suggesting that lead pollution is a global issue. Large increases in lead production occurred with the discovery of cupellation around 5000 years ago, when silver began to be used in coins 2700 years ago, and during the Industrial Revolution. [Reprinted with permission from S. Hong, J.-P. Candelone, C. C. Patterson, and C. F. Boutron, Science, 265, 1841-1843 (1994). Copyright 1994 American Association for the Advancement of Science.]...
Flegal and Smith (1992) have estimated total global lead production since the advent of cupellation to the late twentieth century at about 300 million MT (Figure 3.1). This cumulative tally, as we would expect, was not produced in a smooth monotonic fashion with a stable growth rate in production and consumption. Rather, the record for accumulated lead production (most if not all being the amounts dispersed into the environment) is one of abrupt rise and occasional decline. The reason for this is simply that the nonlinear consumption rates tracked closely the leaps in growth of civilizations and empires. [Pg.43]

Settle and Patterson (1980 see also Figure 3.1 in NAS/NRC, 1993) reported the estimates of annual global lead production rates from the invention of cupellation to the present. Moderate increase in annual production is estimated until around the beginning of the Greco-Roman era, where the first large boosts in lead production accompanied both demands for lead in the Roman Empire and the introduction of coinage and requirements for coinage... [Pg.43]

The first section of this chapter noted that the accumulated global lead production in recorded history from the invention of cupellation to the late twentieth century was 300,000,000 MT. Table 3.2 indicates that over two-thirds of this accumulated global production estimate, 220,625,000 MT, occurred in the period 1900—2009. Of this 220 million MT figure, 180,420,000 MT or 82% of global production for 1900—2009 took place from 1950 to 2009, a period of 59 years. Even more significant, global lead production of 180,420,000 MT in this relatively brief period of recorded history accounted for over 60% of the entire estimated lead production over the previous five millennia of 300 million MT. [Pg.71]

Although this is theoretically convincing, the key question to be answered is whether any of the ancient processes for the production of lead and silver might be expected to give such a large non-equilibrium loss. The most likely contender for a process with such losses seems to be cupellation, in which a melt of around 99% Pb with less than 1% silver is converted via preferential oxidation into an alloy with greater than 95% silver - a total loss in excess of 99% of lead (Budd... [Pg.323]

Lead was widely used in ancient times, dating back over 7000 years. It was often mined and produced as a co-product of silver, which was highly prized for ornamentation and jewellery and later for coinage. Lead served as a collector for silver and gold and often smelting was conducted primarily for this purpose. Lead was separated from the precious metals by oxidation in the cupellation process . [Pg.4]


See other pages where Lead production cupellation is mentioned: [Pg.430]    [Pg.30]    [Pg.4]    [Pg.392]    [Pg.187]    [Pg.27]    [Pg.43]    [Pg.1173]    [Pg.238]    [Pg.53]    [Pg.283]    [Pg.849]    [Pg.854]    [Pg.858]    [Pg.859]    [Pg.557]    [Pg.1173]    [Pg.83]    [Pg.348]    [Pg.6]    [Pg.216]    [Pg.25]    [Pg.241]    [Pg.241]    [Pg.343]    [Pg.321]   
See also in sourсe #XX -- [ Pg.42 ]




SEARCH



Cupellation

Cupels

Lead cupellation

Lead production

Lead products

© 2024 chempedia.info