Lead minerals

Lead is obtained chiefly from galena (PbS) by a roasting process. Anglesite, cerussite, and minim are other common lead minerals. 

Ore Dressing. The principal lead mineral, galena, in most cmde ores, is separated from the valueless components, or gangue. Other valuable minerals that are present in the ore may be recovered either together with the lead, or in a separate step (2,3). Occasionally, the ores are sufftciendy rich in lead and low in impurities to be smelted direcdy. 

Aetivators. These are used to make a mineral surface amenable to collector coating. Copper ion is used, for example, to activate sphalerite (ZnS), rendering the sphalerite surface capable of absorbing a xanthate or dithiophosphate collector. Sodium sulfide is used to coat oxidized copper and lead minerals so that they can be floated by a sulfide mineral collector. 

Gruber HE, Gonick HC, Khalil-Manesh F, et al. 1997. Osteopenia induced by long-term, low- and high-level exposure of the adult rat to lead. Miner Electrolyte Metab 23 (2) 65-73. 

D 1368 23 < 1 mg Pb/L Organometallic lead mineralized by treatment with bromine and steam spectrophotometric determination of dithizone (2) complex. 

Silver oxide lead ores have much different flotation processing characteristics. Although this ore responds to sulphidization-xanthate system, silver recovery in the lead concentrate was usually poor and amounted to about 30 40%. Floatability of lead minerals also was not satisfactory. 

Fleming, M.G., Effect of Alkalinity on the Flotation of Lead Minerals. Transactions of the American Institute of Mining Engineers Vol. 193, pp. 1231-1236, 1952. 

Similar equations can be written for Pb and Pb using their appropriate radioactive parents and decay constants. If t = 0 is taken to represent the time of the formation of the Earth s crust, then these three equations describe the trajectory of the isotopic composition of terrestrial lead from that time. If T is the time elapsed since the formation of the Earth, (i.e., the age of the Earth), and tm is the time before present at which the lead minerals were formed, then, using the assumptions of the Holmes Houtermans model given above, the isotopic composition of a common lead deposit formed tm years ago is given as follows ... 

According to the model, this isotopic composition was fixed tm years ago (on the separation of the lead minerals from the uranium- and thorium-bearing environment), is unchanged to the present day and is therefore measurable. There are two similar equations for the other two radiogenic stable isotopes of lead. To simplify the manipulation, we can use the following notation ... 

Figure 9.13 Lead isotope plots (208Pb/206Pb vs 207Pb/206Pb) (a) EWLIO - galenas from all English and Welsh lead sources (Rohl and Needham, 1998 37) (b) isotopes from French lead minerals superimposed against EWLIO, showing substantial overlap (Rohl and Needham, 1998 71). (From Rohl and Needham, 1998, with permission. The Trustees of the British Museum.)...

Basic toxicity has been identified from careful observation and experimentation in the workplace and in the lab. Over the years, from the time of the ancient Greeks and Romans, and probably long before that, we have learned that exposure to certain substances can cause bodily harm. Hippocrates, the founder of medicine in Ancient Greece, described the occurrence of lead poisoning among lead miners and metal workers as long ago as 400 B.C. The Roman historian, Pliny, described in his encyclopedia in the second half of the first century A.D., the dangers of mercury poison-... 

Ravitz, S. F. and Potter, R. R., 1933. Oxygen-free flotation I flotation of galena in absence of oxygen. Am. Inst. Min. Metall. Eng., Tech. Publ., No.513 Rey, M. and Formanek, V., 1960. Some fiictors affecting the selectivity in the differential flotation of lead-zinc ores in the presence of oxidized lead mineral. Proc. 5 Int. Min. Proc. Congr., Inst. Mining and Met., London, 343 - 352... 

Synonyms Plumbago black lead mineral carbon... 

Although Johann Heinnch Pott knew that it is not a lead mineral, he confused it with graphite, Reissbley, and believed that it contained lime, iron, and sulfuric acid (50). 

Qvist observed that the calx was yellow while hot but glistening white when cold. He obtained positive tests for iron and copper, and found that on digestion, it gave no sweetness to distilled vinegar (an indication that molybdenite is not a lead mineral). In one specimen from England he detected tin. He concluded that it is evident from several experiments that the molybdenite itself contains something specifically metallic in addition to those just mentioned (51). 

Although molybdenite was for several years the only known source of molybdenum, the Abbe F. X. Wulfen in 1785 described a lead mineral from Carinthia which had previously been regarded as lead tungstate, and when M. H. Klaproth analyzed a specimen of it from Bleyberg in 1792-94, he found it to be lead molybdate (76). Two years later, Charles Hatchett examined a larger specimen of it and confirmed Klaproth s conclusion. This mineral is now known as wulfenite. 

A thousand thanks, dear professor, for your kind letter with the beautiful story about the goddess Vanadis, which gave me great pleasure, although, frankly, it vexed me a little, though Only at first, to have made no visit to the beautiful one. Even if I had charmed her out of the lead mineral, I would have had only half the honor of discovery, because of the earlier results of del Rio on erythronium. But Sefstrom, because he succeeded by an entirely different method, keeps the honor unshared. As soon as I know the intimate relations of the metal, and you have sent me a little of it, I will analyze the lead mineral.. . . ... 

Most of his scientific research was done during the decade 1796 to 1806. His first paper in the Philosophical Transactions described his analysis of the Carinthian lead molybdate (4). The celebrated Scheele, said he, in 1778 read before the Academy of Sciences at Stockholm an essay in which he proved. . . that the mineral called Molybdaena was composed of sulfur and a peculiar metallic substance, which, like arsenic and tungsten, was liable by super-oxygenation to be converted into a metallic acid which in its properties differed from any other that had been previously discovered. Hatchett mentioned the confirmatory researches of B. Pelletier, P. J. Hjelm, and Mr. Islmann [J. C. Ilsemann], and added But the existence of this substance was known to be only in that mineral which Scheele had examined. This lead mineral from Carinthia had been described by the Abbe F. X. Wulfen and by N. J. Jacquin. For several years it was believed to be lead tungstate, but Klaproth proved it to be lead molybdate. Since Klaproth had had an insufficient amount of the mineral, Hatchett made a complete analysis of it and investigated the properties of molybdic add. 

The most outstanding achievement of del Rio s long, useful life was his discovery in 1801 of the metal now known as vanadium. He found that the brown lead mineral, Plomo pardo de Zimapan (8), from the... 

Lead Oxide or Lead Tetroxide (Minium, Red Lead, Mineral Orange, Mineral Red, Plumbo, Puce, Orthoplumbate, Paris or Saturn Red). 

Lead sulphide (galena - PbS) is another likely candidate for hydrometallurgical processing particularly in the United States where, apart from the problems of the sulphur dioxide emissions, the lead toxicity problem is making it very difficult for the lead smelters to operate their conventional pyrometallurgical process and comply with EPA and OSHA standards. The total amount of lead mined in the United States is about 600,000 tons per year which, if fully converted, would yield about 100,000 tons per year of by-product sulphur. The Bureau of Mines in Reno, Nevada, have an active pilot plant study to produce lead via a hydrometal-lurigal process (2). In this process the common lead mineral galena is dissolved in an acid brine solution of ferric chloride. 

Major lead mineral in the ore samples identified as sulfides is galena (PbS). 

Ore samples identified as oxides are highly oxidized or gossan ores in which the major lead mineral is also galena. 

Cerussite is of secondary origin, being found associated with other lead minerals, and is widely distributed. There are many European and American localities. Fine crystals have been obtained from Phocnixvillc. Pennsylvania Joplin. Missouri Leadville. Colorado Pima County, Arizona, and Dona Ana County, New Mexico. It is an ore of lead, and frequently carries values of silver. Derived from the Latin cetussa. white lead... 

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