- Email: [email protected]
Improved process for leaching copper ores
NOTES CARBON
FROM THE MONOXIDE
U. S. BUREAU IN
TWO
OF MINES.*
LARGE
GARAGES.
By S. H. Katz and H. W. Frevert.
THE Government Fuel Yards at Washington, D. C., operated by the Bureau of Mines, maintain a large garage for motor trucks and cars used in distributing coal to the government buildings. The Bureau of Mines determined the carbon monoxide in the garage atmosphere over a period of three weeks in January, 1927. Records were also obtained in a large commercial garage Records in Pittsburgh, through most of February to May, 1927. were kept with the continuous recorder developed by the Bureau of Mines. The maximum carbon monoxide noted was as high as 8.9 parts per ten thousand (p.p.t.t.) in the government garage, but In the the average for any working day did not exceed I p.p.t.t. corporation garage the maximum exceeded the recorder limits, 8.3 p.p.t.t. but such high concentrations were only momentary, the highest average for one hour being 4.3 p.p.t.t., which might cause headache in some employees, but the highest daily average was 1.64 p.p.t.t. On the whole, conditions as to carbon m80noxide content were not found to be very bad as regards possible effects on workmen, but in very severe weather when doors are kept more tightly closed, possibly worse conditions may be expected in large garages of the type tested. A more complete report is being issued in Irzdu-tricrl orzd Elzgiu~~eriwg Chctrlistry. IMPROVED
PROCESS
FOR
LEACHING
COPPER
ORES.
A PROCESS for agglomerating fine material in leaching ores has been developed by metallurgists of the Southwest Experiment Station, that promises wide application in the treatment of copper and other ores. The slime and fine particles are caused to cohere together or adhere to the larger particles of the ore, so that fine ores hitherto regarded as impervious to leaching solutions can be _~ Not subject to copyright. * Published by permission of the Director. 51.5
U.
546
S. BUREAU
OF MINES
NOTES.
[J. F. I.
made pkrmeable. The method simply involves the mixing of dry crushed ore with moistening until the fine particles agglomerate, and then leaching in open heaps with a downward trickling solution. Open drainage must be maintained at the b,ottom and the This solution must not be permitted to pool on the surface. principle offers great possibilities for treatment of hundreds of millions of tons of low-grade tailings from copper concentrators carrying 0.2 to nearly I per cent. copper, also to large tonnages of ores that slime in crushing or require very fine grinding.
SEMI-ANNUAL By
MOTOR
GASOLINE
SURVEY.
E. C. Lane, D. J. Condit, and C. S. Lute.
THE motor gasoline survey for June, 1927, is the sixteenth in representative semi-a,nnual survey ,of gasoline bein g marketed cities of the United States. The results show that the gas’oline being marketed this summer is slightly more volatile than that Comparison with surveys for previous marketed a year ago. a years shows that refiners are tendin, ff more and more toward standardized product. The details will be found in Serial No. 2827.
FROM THE MONOXIDE
U. S. BUREAU IN
TWO
OF MINES.*
LARGE
GARAGES.
By S. H. Katz and H. W. Frevert.
THE Government Fuel Yards at Washington, D. C., operated by the Bureau of Mines, maintain a large garage for motor trucks and cars used in distributing coal to the government buildings. The Bureau of Mines determined the carbon monoxide in the garage atmosphere over a period of three weeks in January, 1927. Records were also obtained in a large commercial garage Records in Pittsburgh, through most of February to May, 1927. were kept with the continuous recorder developed by the Bureau of Mines. The maximum carbon monoxide noted was as high as 8.9 parts per ten thousand (p.p.t.t.) in the government garage, but In the the average for any working day did not exceed I p.p.t.t. corporation garage the maximum exceeded the recorder limits, 8.3 p.p.t.t. but such high concentrations were only momentary, the highest average for one hour being 4.3 p.p.t.t., which might cause headache in some employees, but the highest daily average was 1.64 p.p.t.t. On the whole, conditions as to carbon m80noxide content were not found to be very bad as regards possible effects on workmen, but in very severe weather when doors are kept more tightly closed, possibly worse conditions may be expected in large garages of the type tested. A more complete report is being issued in Irzdu-tricrl orzd Elzgiu~~eriwg Chctrlistry. IMPROVED
PROCESS
FOR
LEACHING
COPPER
ORES.
A PROCESS for agglomerating fine material in leaching ores has been developed by metallurgists of the Southwest Experiment Station, that promises wide application in the treatment of copper and other ores. The slime and fine particles are caused to cohere together or adhere to the larger particles of the ore, so that fine ores hitherto regarded as impervious to leaching solutions can be _~ Not subject to copyright. * Published by permission of the Director. 51.5
U.
546
S. BUREAU
OF MINES
NOTES.
[J. F. I.
made pkrmeable. The method simply involves the mixing of dry crushed ore with moistening until the fine particles agglomerate, and then leaching in open heaps with a downward trickling solution. Open drainage must be maintained at the b,ottom and the This solution must not be permitted to pool on the surface. principle offers great possibilities for treatment of hundreds of millions of tons of low-grade tailings from copper concentrators carrying 0.2 to nearly I per cent. copper, also to large tonnages of ores that slime in crushing or require very fine grinding.
SEMI-ANNUAL By
MOTOR
GASOLINE
SURVEY.
E. C. Lane, D. J. Condit, and C. S. Lute.
THE motor gasoline survey for June, 1927, is the sixteenth in representative semi-a,nnual survey ,of gasoline bein g marketed cities of the United States. The results show that the gas’oline being marketed this summer is slightly more volatile than that Comparison with surveys for previous marketed a year ago. a years shows that refiners are tendin, ff more and more toward standardized product. The details will be found in Serial No. 2827.