4,070 research outputs found
Application of alternative lixiviants for secondary heap leaching of gold
Some preliminary results on the secondary leaching of previously heap leached gold ore are presented. Alternative lixiviants for gold comprising chlorine, thiourea and thiosulphate were compared with cyanide using bottle roll tests. Chlorine was subsequently selected for column leaching tests. Column tests at 1.0, 0.1 and 0.01 gL-1 Cl2 at pH 2 were conducted. The results indicated that about 23 per cent of the gold was leached over 45 days using 1 gL-1 Cl2 at pH 2. The experiments conducted proved that the chlorine/chloride system has good potential for further extraction of gold and silver from the existing cyanide heap leach residues and a process for secondary leaching of gold has been proposed. Further testwork is recommended to extend conditions, sample types, and the duration of leaching period
A Common Origin for Quasar Extended Emission-Line Regions and Their Broad-Line Regions
We present a correlation between the presence of luminous extended
emission-line regions (EELRs) and the metallicity of the broad-line regions
(BLRs) of low-redshift quasars. The result is based on ground-based [O III]
5007 narrow-band imaging and Hubble Space Telescope UV spectra of 12 quasars at
0.20 < z < 0.45. Quasars showing luminous EELRs have low-metallicity BLRs (Z <
0.6 Z_Solar), while the remaining quasars show typical metal-rich gas (Z >
Z_Solar). Previous studies have shown that EELRs themselves also have low
metallicities (Z < 0.5 Z_Solar). The correlation between the occurrence of
EELRs and the metallicity of the BLRs, strengthened by the sub-Solar
metallicity in both regions, indicates a common external origin for the gas,
almost certainly from the merger of a gas-rich galaxy. Our results provide the
first direct observational evidence that the gas from a merger can indeed be
driven down to the immediate vicinity (< 1 pc) of the central black hole.Comment: Accepted for publication in ApJ Letters. 4 pages, 1 figure, 1 tabl
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The use of ERTS-1 multispectral imagery for crop identification in a semi-arid climate
Crop identification using multispectral satellite imagery and multivariate pattern recognition was used to identify wheat accurately in Greeley County, Kansas. A classification accuracy of 97 percent was found for wheat and the wheat estimate in hectares was within 5 percent of the USDA's Statistical Reporting Service estimate for 1973. The multispectral response of cotton and sorghum in Texas was not unique enough to distinguish between them nor to separate them from other cultivated crops
Remote sensing for shipwreck location. Or, all your problems solved.
A routine site inspection of a proposed shipwreck salvage excavation revealed a technique with important ramifications for survey archaeology. Its potential may prove disastrous to the present job market for field archaeologists
Deterministic Dicke state preparation with continuous measurement and control
We characterize the long-time projective behavior of the stochastic master
equation describing a continuous, collective spin measurement of an atomic
ensemble both analytically and numerically. By adding state based feedback, we
show that it is possible to prepare highly entangled Dicke states
deterministically.Comment: Additional information is available at
http://minty.caltech.edu/Ensemble
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