The aim of instruction in a metallurgical laboratory is to make real the principles on which metallurgical processes and operations are based, and to foster the spirit of investigation. The materials with which experiments are carried out are ores, metals, and metallic compounds. The method varies with the end sought. A class may work as … Read more
Summarizing some of the principal points brought out in this laboratory Jigging of Minerals’ investigation, I believe the following may safely be accepted: The pulsion-reaction is by far the most important one in the process of jigging. During this period, with sized grains of different specific gravities, with proper pulsion-velocity, the separation between them will … Read more
The jig, in one form or another, continues to hold a leading place among the machines designed to separate two or more minerals of different specific gravities. It is simple in construction, easily operated, capable of treating large quantities in a short time, and highly efficient under various conditions. The question, whether the material to … Read more
Concentration of grains from 10 to 30 mm. is effected by hydraulic jigs with two compartments, and in the case of the smaller grains down to 2 mm. by jigs with five compartments. The construction of the jigs is the same in both cases. Fig. 3 gives the details of a jig with two compartments; it … Read more
The methods employed in dressing the tin ore up to the required percentage of purity depend mainly on the type of ore crushed. These may be briefly divided into two distinct classes—viz., a free milling ore and a complex milling ore. In the former the ore is practically free from the common metallic sulphides, such … Read more
Supposing that a claim is suitable for hydraulic sluicing, the first thing to do would be to ascertain what is the probable volume and pressure of the water supply. This can be closely approximated by means of an aneroid survey. The facilities for the disposal of the tailings should next be ascertained. As mentioned before, … Read more
In considering the prospective value of dredging ground there are many conditions to be taken into account besides its actual gold content; it is like all other classes of mines in this respect. As a prominent mining engineer recently said: ‘‘Each mine is a law unto itself.” Likewise each dredging scheme must be considered strictly … Read more
The working of gold alluvial deposits by dredging has from all times been a popular form of mining, not only from the simplicity of its operations, but also, in its more primitive stages, from the possibility of carrying it on without large capital, without skilled labour, expensive plant, long terms of preparatory work, or, in fact, any … Read more
Any amalgamation test is found to possess most merits and fewest limitations when reduced to the smallest possible dimensions permitting uniform action and certain treatment. A limit is always reached at some point in this reduction in size, where some condition no longer can be fulfilled. In many continuous mechanical tests the limit is set … Read more
I tested an ore, which was peculiarly difficult to treat, on several concentrators then in general use, including the Frue-vanner, the Luhrig table and the Cornish buddle. Owing to the character of the ore it had to be crushed- to a very fine state of division, and the results obtained were far from satisfactory; a … Read more