COROCORO COPPER DISTRICT OF BOLIVIA 85 



The flow sheet of the three mills is essentially the same 

 and only that of the Guallatiri Chico will be described. 

 The ore comes to the mill crushed to 4" size and is dumped 

 from the serial tram into a bin that feeds 3 Chilean mills. 

 The pulp passes over a 1-5/2 mm. screen, the oversize of 

 which is shoveled back into the mills. The undersize is 

 elevated to a classifier, the settlings of which feed two 2- 

 compartment Harz jigs with 2-mm, screens. The two 

 compartments of the jig produce a 60 per cent copper con- 

 centrate that is retreated on a third jig to produce an 85 

 per cent concentrate. The tails of all the jigs are returned 

 to the Chilean mills. Four Wilfley tables receive the over- 

 flow of the classifier from a distributing spitzkasten. They 

 make an 85 per cent concentrate, middlings that are 

 reground in the Chilean mills, and tails that carry .5 per 

 cent copper, which are run in a sluice to settle. The sett- 

 lings are also returned to the Chilean mills. In 1919 the 

 Guallatiri Grande mill was shut down and the Guallatiri 

 Chico and Guaychuni were treating 180 tons of ore daily. 

 The recovery of these mills is given as 70 per cent and 

 equivalent to an ore tenor of 2.3 per cent copper. 



In 1919 the Corocoro United Copper Mines completed 

 its flotation plant on the east side of the Guillatiri River, 

 l /4 km. below the Guillatiri Grande mill. Since 1912 this 

 company had also been shipping high-grade copper sulphide 

 and sulphate ores running 20 to 25 per cent copper, and on 

 the completion of the flotation plant began the utilization 

 of its lower-grade sulphide ores in the Vizcachani mine. 

 The ore comes to the Guallatiri Chico mill by the serial 

 tram and is thence transported on a horse-drawn tram to 

 the flotation plant. On arriving there, the cars are raised 

 on an incline and dumped into a bin at the top of the mill. 

 The ore is discharged from the bin over a grizzly and the 

 oversize fed to a 9 x 15" jaw crusher. The crushed ore 



