Mohave County miner and our mineral wealth., 1920-01-31
A NEW FLOTAT|ON
 SYSTEM IS BEING
 INSTALLED IN COLO.

A new system of floating minerals from ore is being installed in Colo rado. Although the system has been little heard of in the west, it has been in successful use in other parts of the world since early in 1916. Its inven- tion took place in Canada and prac- tical, commercial use of it has been continuously carried on in the Cobalt field, especially where it has proved decidedly efficient in the concentra- tion of silver ores.
 MT. Groch, the inventor, recently, spent some time in Denver making demonstrations with a portable ma cine on ores from Boulder and Clear Creek counties. His results were most gratifying and resulted in the place ment of an order for a complete set of units of the Groch type to be plac- ed alongside of set of Notation units of corresponding capacity of a well known western type. MT. Groch is confident that his machine will make the superior showing in commercial practice.
 The system is particularly we'll suited to the different Notation of minerals for the reason. that various oils may be fed into the different shafts in the different cells all the way from the feed end to the dis charge end. Since the oil is fed into the machine at the same points that large volume of air are sucked into the pulp, the effect is complete atomization of the oil and its intimate mixture with the air, water and ore. This results in a most dense shower of infinitesimal bubbles These bub- bles, because of their minuteness and the pressure to which they are sub jected, tend to become absorbed and, in practically nascent state, to re- form around each lustrous mineral particle as a nucleus, thus forming a minute, tough bubble or cell. Condi- tions of this sort ar essential for eff ficent Notation work.
 The selective or differential flota- ton of the different minerals in an ore is accomplished in the Groch ma chine by feeding the lighter oils at the head or feed end of the machine in this way securing a float of certain minerals in the first cell ,and then adding oils of gradually increasing density throughout the remaining cells until the heavy coal tars may be used in the tailing end. As the character of the oiling varies, differ ent minerals are collected in the froth. It is a. very interesting and note worthy characteristic of this machine that there is no danger of using too much oil. Experiments in oil-flooding have been carried on and it has been found that there are no delecterious effects but that, on the other hand, the excess oil creates a better grade concentrate than that usually obtained with the ordinary amount of oil. In some experiments the different oils introduced into the machine amounted to more than 25 pounds per ton of ore, and the extraction (on a silver ore) was over 90 per cent.
 The system consists of series of centrifugal Venturi tubes within a centrifugal runner attached to hol- low shaft and is mixed with the pulp which enters the runner from below. Oil is fed with the air. Millions of small globules or cells are formed at the circumference of the runner. These cells resemble caviar in ap- pearance but they are really very tiny, tough bubbles of air coated with oil and mineral. This cellular action per mits the gangue to settle away from the concentrate which promptly rises to the surface of the agitation com partment and then floats over the sep aration compartment and into the con- centrate launder. The concentrate is very clean.
 No outside emulsification is needed as the air is oiled during its passage down through the hollow shaft and is ready to be formed into bubbles the instant it is discharged from the peri phery of the runner together with the pulp.
 During his experiments in Denver, MT. Groch tried oils distilled from oil shale and was impressed with the commercial possibilities in the use of shale oil fractions in the separation of lead and zinc minerals.
 With the present interest in the re- vival of activities in the older mining districts it will be found that success will be attained in the mining of low grade ores, in the majority of in stances, only when efficient and cheap methods are installed for making clean concentrates of the minerals. Flotation will be found the best con centration scheme and it is essential that the process selected will permit such selective Notation as to make separate products of those minerals upon which the smelting and other