118 



DRESSING OF ORES 



k &', wheels on jigger shafts ; I, discharge valves, 3 inches diameter ; m t collecting lx>xes, 

 12 inches wide ; o, receptacles, 15 inches wide. The piston-stroke is either lengthened 

 or shortened by shifting and fixing the pins in the slotted discs ; and, if necessary, 

 slides are fitted to the discharge ways, for the purpose of modifying the thickness of 

 the separating beds. 



Fine Sand Jigger. The Jigging Machine shown in figs. 697 and 698 is employed at 

 a great number of silver, lead, and blende mines in Germany, and elsewhere, for the pur- 



697 698 



pose of treating sand, classified or sized, into suitable sots of grains from % to 2 milli- 

 meters in diameter. The construction is rendered apparent from the longitudinal and 

 transverse sections, the sieve bottoms are 34 inches long and 15 inches wide, depth of 

 sieve from top of hutch lOJ inches, and from discharging slot 3 inches, piston 30 

 inches long, 15 inches wide, and 4 inches thick. The box for discharging rough 

 sand is 3 inches wide and 9 inches deep. The plug-valve for regulating outflow of 

 stuff, 1 inch diameter ; launder 3 inches wide, for taking off fine sand ; plug valves 

 l inch diameter, for discharging stuff from sieve boxes. The outside dimensions 

 of hutch are as follow: length, 12 feet, 9 inches; width, 3 feet, 9 inches; height, 3 

 feet. For treating grains, say, millimeter in diameter, the piston should make about 

 200 strokes per minute, with a length of stroke of from to f ths of an inch. For 

 enriching and separating blende and lead ore the first two separating beds should be 

 of lead ore grain from 3 to 4 millimeters diameter, and the other separating beds of 

 coarse blende grains. The depth of beds must depend. upon the richness and volume 

 of stuff flowing into the apparatus within a given time. For the No. 1 sieve, it may 

 be about 3 inches; No. 2 sieve, 2 inches; No. 3 sieve, 1^ inch; and No. 4 sieve, 1 

 inch or less. 



699 



Slime Jigger. This jigger, jig. G99, is in use at Iserlohn, Prussia, for enriching 

 sand composed of clay, carbonate of lime, blende, and lead ore. The jigging is per- 

 formed on the sieve ; the ore and orcy stuff being progressed into receptacles. In 

 this respect it differs from those fine sand jiggers, where the orcy products pass, through 

 a coarse grain bed and sieve, into V-shaped boxes. 



