The weekly Alaska citizen., 1917-11-19
BUREAU IF MINES EXPERIMENT STATION
 Series of Articles Explaining Its Origin and Purpose

IL" BgIsteT-ON ONeEStIoih hds lHdue some phenomenal records in the past two or three years both as to capacity and quality of products. IL Is provided with two interchangeable decks. one for coarse and one for fine size work The Wilfley table, which k and has been the standard type of concentrating table for the last fifteen or twenty years. has two interchangeable decks for different types ol concentration. The Card table has but the one deck equip ped for line work. These tables are exactly one-haIf the regular dimen- SIone. and although in general all three types are used for the same class of work, there are detailed diff ferences in the design of the tables, the direction of the shaking motion, and the arrangement of the rifles, or ridges. which catch the heavier minerals, which render each table more adaptable for certain kinds Of ore.
 The feed for these tables will be secured through cIassIfiers in which the heavier and larger particles of ore sink through an upward current of water and are discharged at the bottom 10 furnish the table feed, the lighter and smaller particles of ore being carried upward by the current and oyerflowing to another similar but larger cIassifIer with d slower raising current of water which again furnishes a finer size product for table concentration. Thus one, two or even more classified pro ducts can be made for the table feeds
 as may be found necessary.
 The cyanlue equipment in addition to the crushing and grinding machin- cry referred 10 above includes d Dorr Thickener and its function is to separate an excess of water from the pulp" or ground ore. This con siSts of a wooden tank F feet in diameter and $ feet high provided with two arms which reYolye slowly near the bottom of the tank and 5crape any particles of sand and slime which settle there toward the center Of the tank, where they are dischargd through a pipe and valve. The clear water oyertIOws at the top. \ PachuCa tank feet in dla- meter and feet high with an air lift for stirring and agitating the ore and cyanide solution is also proyid- ed The gold and silver. values in the ore are dissolved during the agt- tation period in the Pachuca tank. The strength of the cyanide solu- ton, the thickness of the pulp, the length of time necessary for the Bo- lution of the values, the amount of lime and other possible reagents re qured being determined beforehand in the laboratory. There is also an Oliver Filter feet in diameter which separates the sand or tailings from the cyanide solution after the values have been dissolved. This machine consists of a revolving drum which is covered with canvas and wrapped with piano wire and submerged in the pulp. It is so arranged that during the first half revolution of the drum there is a suction behind the canvas which draws the cyanide solution through, leaving the sand attached, as a cake, to the outside of the drum. During the next DOT tion of the revolution, the suction still continuing, the attached cake is washed with water to free it from any cyanide solution which may be left. During the remainder of the revolution air under pressure is fore ed through the canvas from the in side and the cake of sand or tail ings is blown and scraped off.
 The thickened pulp from the Dorr Thickener is delivered by the Krogh Centrifugal Pump to the Pachuca tank, where the dissolving action of the cyanide solution takes place, after which the sand solutions are separated in the Oliver filter. The station will also be equipped to make small sized, preliminary cyanide tests which are valuable for the rapid de termination of the amenability Of an ore to the cyanide method of treat ment.
 Three types of Notation machines have been purchased. These are the Callow, the Janney and the TX & k'' covering the entire field of Notation devices as developed in the latest nractice Their function is to stir