54 BULLETIN 1003, U. S. DEPARTMENT OF AGRICULTURE. 



USE OF OIL FOR ORE FLOTATION. 



Of the many oils that have come into use for ore flotation, oil 

 of eucalyptus, costing about $1.50 a gallon, is prized most highly. 

 Next in the order of merit come the pine oils, selling for from 40 

 to 60 cents a gallon. In the effort to discover cheaper oils, most of 

 the wood creosotes, as well as many coal-tar creosotes, have been 

 found to be acceptable. They range in price from 15 to 30 cents a 

 gallon. Producers of petroleum have also entered the flotation field, 

 though with but limited success when petroleum alone is used. 

 Better results are obtained by mixing a small amount of pine or 

 creosote oil with the crude petroleum. "Kerosene sludge acid" 

 from California oils, obtained by treating the crude oil with sul- 

 phuric acid in the refining process, is also being sold for flotation. 

 The sludge acid from coal tar is said to have a flotation value as 

 good as or better than that from petroleum, and even coal tar itself 

 is extensively used because of its low price. 



These different products entering into ore flotation may be divided, 

 in a general way, into two classes, known as " frothing agents," 

 which promote foaming, and "collecting agents," the function of 

 which is to coat with a film of oil the mineral particles only, so 

 that, adhering to the air bubbles in the foam, they are thus sepa- 

 rated from the gangue. While all oils possess both frothing and 

 oiling or collecting properties in some degree, eucalyptus oil, the 

 pine oils, pine-tar oils (the "light" and "heavy" oils of this pub- 

 lication), and crude turpentine are primarily used as frothing agents. 

 Coal tar, pine tar, together with hardwood tar, and " sludge acid " 

 are used as collecting agents. Success in ore flotation demands a 

 proper adjustment of these two physical properties to the particu- 

 lar requirements of the ore to be treated. While all of the products 

 mentioned can be used in proper combination, with some measure of 

 success, the pine oils occupy a commanding position in the field of 

 ore flotation. 



Samples of pine oil and of the crude distillates obtained in the 

 retort work were submitted for flotation tests to the Bureau of 

 Mines Metallurgical Experiment Station, Salt Lake City, Utah, to 

 ore mills in the Coeur d'Alene district, and to the testing department 

 of a large copper mining company. The results from their tests 

 showed that the crude turpentine was virtually as effective a flota- 

 tion agent as the pine oil, and even the light and heavy oils were 

 applicable, though requiring a greater proportion a ton of slime, 

 especially in the case of the heavy oil. Even the acid liquor was 

 found useful on certain pyrite ores. 



Where, therefore, the efforts of the producers were formerly di- 

 rected toward refining the crude distillate to recover a maximum 



