METALLURGICAL PRACTICE. 45 



CHAPTER V. 

 METALLURGICAL PRACTICE. 



Milling. — Since the Champion lode yields when properly sorted 

 a clean quartz with practically no admixture of clayey matter, there is 

 no tendency to the formation of intractable slimes, even when com- 

 minution is carried to a considerable degree of fineness. Taking this 

 fact in connection with the high grade of the ore as to gold-contents, 

 it is not surprising to find that the practice at the bigger and richer 

 mines of the Kolar gold-field aims at a good mill extraction rather 

 than a high stamp duty. Inside amalgamation is practised at the 

 two leading mines (the screening in use having 1,600 holes to the 

 square inch at Mysore and 1,200 at Champion Reef, and the depth 

 of discharge being 7 inches at Mysore, 6 at Champion Reef), 

 the object being to liberate and amalgamate as much of the 

 gold as possible in the battery boxes in order to prevent amalgam- 

 stealing. 



A high mill extraction necessitates a low stamp duty. At the 

 Mysore Mine it averages 2*27 and at the Champion Reef only 2 tons 

 per stamp per diem, with stamps weighing at Mysore i,05olbs. (120- 

 head)and 750 lbs. (30-head) and 85olbs. at the Champion Reef. The 

 highest duty on the field, namely, 2*7, is that performed by the 

 Balaghat mill with 1,150 and 1,0501b. stamps and a depth of 

 discharge of only two inches. The average of the whole field is 

 2*22 tons per diem. 



The number of stamps at present dropping on the field is 585. 

 In addition to these there are 60 lying idle, pending further develop- 

 ment of the mines, and 120 in course of erection at the new Champion 



