206 MINING INDUSTRY, 



SECTION II 



DETAILS OF MAOHINEKY EMPLOYED IN CEUSHING AND AMAL- 



GAMATING.i 



The macliinery of a mill for the treatment of silver ores by the "wet 

 process," or method just indicated, consists of rock-breakers and stamps for 

 crushing ; pans, for grinding and amalgamation ; settlers, for the separation of 

 the quicksilver and amalgam from the pulp ; agitators, which are supplemen- 

 tary to the settlers, and save escaping quicksilver; various apphances for the 

 concentration of the residue, or "tailings;" the retort for the sublimation and 

 separation of the quicksilver from the precious metals; besides the motive 

 power and its auxiliary parts. 



The rock-breaker generally in use is Blake's. It serves simply to crush 

 the large pieces of rock to fragments of smaller size, not exceeding a few 

 cubic inches, which are then conveniently supphed to the stamps. The 

 machine is well known, not only in mining regions but throughout the 

 country, being employed in breaking stone for road-making and other pur- 

 poses. It hardly needs a detailed description here. 



Stamps. — The stamps consist of a series of heavy pestles of iron, which 

 are lifted to a height varying from 7 to 15 inches, and allowed to fall upon the 

 ore that is to be crushed. They work in a mortar or trough, also of iron, into 

 which a constant supply of ore is introduced, and from which the crushed ma- 

 terial escapes through openings furnished with closely fitting screens, as soon 

 as it is reduced to the desired degree of fineness. The mortar is usually rectan- 

 gular in form, and contains from three to six, commonly five, stamps, forming 

 what, in this country, is called a "battery." The mortars rest on a solid 

 foundation, and are established in a substantial framework of timber. The 

 stamps are lifted by means of revolving cams or arms of iron, keyed to a cam- 



^ Althougli the writer has prepared this section almost entirely from his own notes 

 or personal observation, he has made frequent reference to several well-known works, 

 chief among which is KiisTEL's Concentration and Chlokination, an excellent 

 treatise on the mechanical preparation of ores. Professor Gaetzsohmann's valu- 

 able work, "Die Aufbereitung," and Eittinger's " Lehrbuch der Aufbereitungs- 

 Kunde," are commended to the student as complete and thoroughly scientific discus- 

 sions of the same subject. 



