METALLURGICAL METHODS AT BROKEN HILL. 303 
The first attempt to concentrate the crude sulphide ores was, I 
believe, made at the British Mine, and it was an unqualified failure 
so far as the commercial side of the question was concerned. 
Constant trials were made at the Proprietary Mine with varying 
success ; but it is safe to say that until the Hancock jig was 
introduced at Block 14, all the efforts at profitable concentration 
of the low-grade sulphide ores were unmistakable failures. Lessons 
had been learned by the various companies regarding expenditures 
on concentration schemes, and they all waited until Block 14 
had demonstrated that something could be done with this jig. 
Then the South Mine installed them, and then the British 
Company. 
The recovery of the first jigs did not amount to more than 48 
to 54 per cent. of the lead ; but in spite of the low recovery the 
size of the jig allowed large quantities of ore to be rushed through 
them at the minimum of cost. As soon as it was found that some 
profit could be made out of the hitherto hopeless sulphide ore, 
even with such an extravagant loss of lead, more attention began 
to be paid to the re-treatment of material rejected from the last 
hutches. These were crushed finer and passed through a second 
jig, and the same process was gone through with the low-grade 
product of the hutches of this jig, passing it through a third jig ; 
so that with the addition of slime buddles something like 65 per 
cent. to 75 per cent. of the lead contents of the ore treated is now 
recovered from the crude ore. The crushing machinery adopted 
for the ore with these jigs is the ordinary jaw-crusher, on the 
old Cornish principle, with a set of Cornish rollers for finer 
pulverisation. 
A new jig which is bearing the test of work and competition 
against the Hancock jig is that known as the ‘‘ Warren and May’s 
Improved Double Plunger Jig.” These jigs are working on a large 
scale at the Block 10 Mine, Broken Hill, and have been adopted 
by the Junction Company. The Proprietary also decided to adopt 
them after most careful tests against the Hancock jig. The fol- 
lowing is a description of the Warren jig :— 
The ore is crushed to pass through a trommel, pierced with a 
rectangular slot 16 gauge wide and a bare quarter of an inch in 
length. From the trommel the crushed ore drops into the receiver 
with a perforated bottom, through which it passes into a Warren 
patent slime separator. This separator is a revolving basin or 
pan with an adjustable overflow in the centre. The water, with 
the slime in suspension, passes down the centre while the ore drops 
to the bottom of the pan and is wiped out by a volute-shaped 
plate, comparatively free from slime or water, over a lip, into the 
sleeves of the jigs. The plungers are connected by a rod with a 
rocker, the length of the stroke given to the plunger being regu- 
lated by a pin, which may be moved in or out along the slot in 
