ee 



BULLETIN 42, UNITED STATES NATIONAL MUSEUM. 



sieve goes to the secoud sieve, yielding scrapiugs which are recnisbed, 

 hutch work, sometimes recriished, sometiraes sent direct to No. 3 jigs, 

 and chats. The material passiug through the 7- millimetre screen goes 

 through a series of five hydraulic classifiers. The settlings from the first 

 classifier go to the second set of twelve 2-sieved jigs, yielding from the 

 first sieve scrapings, good mineral, and hutchwork, sometimes sent to 

 third jigs, but with rich rock is good mineral, from the second sieve 

 scrapings sent to recrushing rolls, hutchwork to third sieves, and 

 chats. 



The settlings from second and third classifiers go to the third set of 

 eight 3 sieved eccentric jigs, yielding from the first sieve scrapings and 

 hutchwork, good mineral. From secoud sieve scrapings, pyrite, and 

 hutch w^ork, retreated on faster jigs. From third sieve scrapings, sent 

 back to first sieve, or with rich rock, pyrite, hutchwork, retreated on 

 faster jigs, and chats. The settlings from the fourth and fifth classifi- 

 ers are treated on slime tables. 



The various materials sent to the recrushing rolls are treated after 

 crashing in the fourth set of eight 3-sieved jigs, yielding from the 

 first sieve scrapings and hutchwork, good mineral. From second sieve 

 scrapiugs, pyrite, and hutchwork sent to the old mill. From third 

 siev^e scrapings, pyrite, and hutchwork sent to the old mill, and chats. 



The old mill treats the hutchwork from the second and third sieves 

 of the fourth set of jigs, and rich chats from the main mill. The ma- 

 terial is first crushed and then passes through a j3-millimetre screen 

 and the coarse material recrushed. The fine stuff goes to a hydraulic 

 classifier, the settlings from which, 3 to 1 millimetre, go to the first of 

 two 2-sieved end lever jigs and two 3sieved eccentric jigs. These 

 yield from the first sieve scrapings and hutchwork, good mineral, 

 from the second sieve scrapings, pyrite, and hutchwork, from third 

 sieve scrapiugs, pyrite, hutchwork, and chats. 



The overflow from the classifier carrying fine material is treated on 

 slime tables, yielding as end products heads, good mineral, and tails, 

 rejected. 



The various steps in this process are illustrated by the following 

 specimens : 



(1) Hutchwork, jig A, sieve 1. (54938.) 



(2) Hutchwork, jig A, sieve y. (54942.) 



(3) Scrapings, jig B, sieve 1. (54944.) 



(4) Hutchwork, jig B, sieve 1. (54948.) 



(5) Scrapings, jig C, sieve 1. (54962.) 



(6) Hutchwork, jig C, sieve 1. (54949.) 



(7) Scrapings, jig C, sieve 2. (54947.) 



(8) Hutchwork, jig C, sieve 2. (54958.) 



(9) Scrapiugs, jig D, sieve 1. (54946.) 



(10) Hutchwork, jig D, sieve 1. (5494L) 



(11) Scrapings, jig D, sieve 2. (54939.) 



(12) Scrapings, jig D, sieve 3. (54950.) 



(13) Chats, jig D, sieve 3. (54960.) 



The metallurgical treatment is illustrated by the following speci- 



mens : 



Ore. 



(1) Koasted mineral. (54896.) 



(2) Koasted sulphides. (54940.) 



