Extraction from Lead Ores

For lead ores with higher silver contents the amalgam and cyanide methods described for gold are possible, but little use is made of them today. 

2 A Modem Method for Lead Ores, Poor in Silver 

Silver is much more soluble in zinc than in lead. In the Parkes process, zinc is added to a lead melt A silver-rich zinc phase forms on the surface and is drawn off When zinc is removed by distillation, raw silver remains. Very pure silver is obtained by a subsequent electrolytic process. 

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Over 95% of failed lead—acid batteries are recycled in these pools, yielding secondary lead which is re-used for the manufacture of new lead—acid batteries. The secondary lead is purified to a degree, allowing its utilization in the production of leady oxide and lead alloys. A certain amount of primary lead extracted from lead ores is also added to the lead pool and used in the manufacture of leady oxide. Thanks to the high percentage of recycled secondary lead and the simple technology of manufacture, the lead—acid battery is the cheapest chemical power source available. 

Germanium, tin, and lead have relatively low abundances in the earth s crust (Table 19.4, page 823), but tin and lead are concentrated in workable deposits and are readily extracted from their ores. Tin is obtained from the mineral cassiterite (Sn02) by reducing the purified oxide with carbon ... 

Local stress is a potent cause of corrosion and may occasionally lead to distressing events, e.g., the falling off of a car door. Metals extracted from their ores may have been at one stage in a liquid state. They cool and solidify, thus introducing local stress points. Further, even in a solid that has not been subjected to stresses in its treatment, stress develops at its dislocations. 

Of interest also is the high-temperature liquid-liquid extraction of molten silver dissolved in molten lead, the extraction solvent being molten zinc (Parkes process) this process is analogous to the familiar extraction of bromine from water using carbon tetrachloride, and is used to recover silver from lead ores. 

The elements of group IVb of the periodic table are germanium, tin, and lead. Germanium is intermediate in its properties between silicon and tin. A brief statement about its properties and uses is given below. Tin and lead are ery important metals. They are easily extracted from their ores, and have been known since ancient times. The metals themselves and their alloys have many uses. 

Yet the reader is not to suppose that the ore of copper is to be chosen in consequence of that assertion, as preferable to others no, the mercury, which is the metallic seed, is attainable from ah, and is easier to be extracted from lead, which is confirmed by the true adepts, advising us to seek for the noble child where it lies in a despised form, shut up under the seal of Saturn and, indeed, let it be supposed, for an illustration of this subject, that any one would propose to make malt, he may effect his purpose in the other corns, but barley is generally chosen, because its germ is made to sprout by a less tedious process, which is to all intents and purposes... 

The metal itself does not occur naturally and is extracted from its ores using long established but ever improving technologies. Crude ore is first roasted in large batches until part of it has been converted to lead oxide and lead sulphate. The air supply is then turned off and the temperature... 

The above principle is made use of in the desilverisation of lead by Parke s process. Silver is extracted from the ore argentiferous lead using molten zinc in which it is 300 times more soluble than in molten lead. Molten lead and molten zinc behave as the two immiscible solvents and the process is carried out at 1073 K. The upper zinc layer is richer in silver from which silver is removed by distilling off zinc. By repeating this extraction three or four times, almost whole of silver is removed from argentiferous lead. 

Polymers containing 8-hydroxyquinoline appear to be selective adsorbents for tungsten in alkaline brines (95). In the presence of tartrate and citrate, quinaldic acid [93-10-7] allows the separation of zinc from gallium and indium (96). Either of these compounds can selectively separate lead and zinc from oxide ores as complexes (97). It is also possible to separate by extraction micro quantities of rhenium(VII), using quinoline in basic solution (98). The... 

In the presence of oxygen, aqueous sodium cyanide dissolves most metals in the finely divided state, with the exception of lead and platinum. This is the basis of the MacArthur process for the extraction of gold and silver from their ores that, in the case of gold, may be represented as follows ... 

In the most common hydrometallurgical process for zinc manufacturing, the ore is leached with sulfuric acid to extract the lead/zinc. These processes can operate at atmospheric pressure or as pressure leach circuits. Lead/zinc is recovered from solution by electrowinning, a process similar to electrolytic refining. The process most commonly used for low-grade deposits is heap leaching. Imperial smelting is also used for zinc ores. 

Deville and Debray A process for extracting the platinum metals from their ores. The ore is heated with galena (lead sulfide ore) and litharge (lead oxide) in a reverberatory furnace. The platinum forms a fusible alloy with the metallic lead, which is also formed. Invented by H. E. St-Claire Deville and H. J. Debray. 

Eluex An early process for extracting uranium from its ores, using both ion-exchange and solvent extraction. Developed by the National Lead Company, United States. 

Imperial Smelting A process for simultaneously extracting zinc and lead from sulfide ores, developed and commercialized by the Imperial Smelting Corporation at Avonmouth, UK, after World War II, and now widely used. Based on an invention by L. J. Derham in which the vapors emerging from a reducing kiln are rapidly quenched in a shower of droplets of molten lead. The first trial was made in 1943 but most of the development work was done from 1945 to 1947. Eleven plants were operating in 1973. 

Leidie A process for extracting the platinum metals from their ores by fusion with sodium peroxide, followed by a complex separation process. Developed by A. Quennessen, a leading French manufacturer of platinum in the 19th century, and E. Leidie. The process is still used for extracting precious metals, and in chemical analysis. 

QSL [Queneau-Schumann-Luigi] A submerged smelting process for extracting lead from its ores and secondary sources. Pellets of sulfide ore concentrate are fed into a bath of... 

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