UNEXPIRED PATENTS
UNEXPIRED PATENTS.
FRANCIS EDWARD ELMORE, in British patent No. 21,948, Oct. 18, 1898, described a flotation process that involved the idea of oil-selection and the idea of oil-buoyancy flotation. He mixed the ore with several times its weight of water, and an equal or several times greater weight of oil in a revolving drum, so constructed and operated as to give a mixing effect without breaking up or emulsifying the oil, which was added with the ore. After thus gently mixing, the mass was allowed to run into a spitzkasten, where the oil carried the sulphides to the surface, and the gangue and water were removed from the bottom. This patent marks a decided advancement in flotation-concentration ; it was the first process of the kind to approach commercial success.
FRANCIS EDWARD ELMORE, in United States patent No. 653,340, April 10, 1899, duplicated in the main his apparatus in the British patent just described.
FRANCIS EDWARD ELMORE, in United States patent No. 676,679, April 10, 1899, duplicated his process described in British patent No. 21,948, Oct. 18, 1898.
ALEXANDER STANLEY ELMORE, in British patent No. 6,519, Mar. 28, 1901, described a method of increasing the selective action of oil by adding acid to the pulp.
ALEXANDER STANLEY ELMORE, in United States patent No. 689,070, April 13, 1901, duplicated the process described in British patent No. 6,519, Mar. 28, 1901.
EDMUND L. VAN DER NAILLEN. in United States patent No. 737,533, June 20, 1901, described an apparatus for ore concentration having a horizontal section decreasing in area upward. This patent is of limited interest.
JOHN KLEIN, in United States patent No. 696,739, July 12, 1901, described a machine to which air was introduced for the purpose of carrying a portion of the ore off the top of the liquid and allowing the balance to sink. This is a patent of limited interest in this discussion.
ALEXANDER STANLEY ELMORE, in British patent No. 15,526, July 31, 1901, described two forms of apparatus for conducting the processes previously patented by Francis E. Elmore. One form was designed to effect the separation of sulphides from the gangue by oil-buoyancy flotation, and differs little in principle from the apparatus described by Francis E. Elmore in his original patent. The other form of apparatus described is intended to effect the separation by a sort of oil-amalgamation, in which the oiled pulp flowed under and in contact with an oiled or greased canvas belt, which carried the oil and oiled mineral out of the pulp. This patent is of interest in that the latter process therein described is extensively used at Kimberley, in South Africa, to separate diamonds from the blue ground.
ALEXANDER STANLEY ELMORE, in United States patent No. 692,643, Aug. 8, 1901, duplicated the apparatus described in British patent No. 6,519, Mar. 28, 1901.
ALEXANDER STANLEY ELMORE, in United States patent No. 703,905, Aug. 8, 1901, duplicated British patent No. 15,526, July 31, 1901.
CHARLES VINCENT POTTER, in United States patent No. 776,145, Jan. 14, 1902, duplicated his British patent No. 1,146, Jan. 15, 1902.
CHARLES VINCENT POTTER, in British patent No. 1,146, Jan. 15, 1902, described a process of mineral flotation wherein the flotation was accomplished in a I to 10% acid solution. He added one ton of this solution to one ton of ore, agitated freely, and applied heat. As the temperature of the pulp increased, the heat caused, he says, the sulphides to rise to the surface, from which they were allowed to flow continuously or were skimmed. This patent deserves honourable mention, as it led to the recent decided development in flotation methods. Potter did not mention the use of any gas, but it is clear that he had in view a gas-bubble process.
HAULTAIN & STOVEL, in British patent No. 9,521, April 24, 1902, described a machine of the familiar Frue-vanner type, in which the concentrating belt was made of canvas, and was coated with a layer of thick oil. They thus took advantage of the well known specific gravity separation, and combined with it the principles of oil-selection. They separated the concentrate from the oil in hot water, when the oil, becoming fluid, rose to the surface, and the sulphides remained at the bottom.
CHARLES W. MERRILL, in United States patent No. 728,487, May 12, 1902, described a concentrating apparatus with a horizontal section decreasing upward. This patent is of just sufficient interest to be mentioned for the sake of completeness. ALCIDE FROMENT, in British patent No. 12,778, June 4, 1902, described a flotation process that involved the use of oil, and also of a gas. He recognized clearly the important principle, which is emphasized in later developments, that when ore, water, oil, acid, and a gas are mixed and agitated together in the proper proportions, the oil not only has a selective action for the sulphides, but the gas also has a selective action for the oiled particles, and it is not necessary to have a large amount of oil present to float the sulphides by oil-buoyancy. He mixed the ore with three times its weight of water, and added a small quantity of oil. If there was no gas-forming mineral in the ore, a little limestone was added, and then also a small quantity of acid, which generated carbon dioxide in the pulp. He then agitated freely. He says the oiled mineral particles collected in spherules and were carried to the surface by the gas bubbles. Finally, he enunciates this important principle : The rapidity of the formation of the spherules and their ascension is in direct ratio to the quantity of gas produced in the pulp in a given time/ This patent was taken out only in Great Britain and Italy.
JOSEPH BARTON SCAMMELL, in British patent No. 15,280, July 9, 1902, described a method of thickening oils by the addition of sulphur chloride in order to increase the buoyancy of the oil and so increase the efficiency of the oil-buoyancy flotation processes. He agitated the ore, water, and sulpho-chlorinated oil in a suitable vessel, transferred the mass to settling-pans, and after a time skimmed the oil with the sulphides.
GUILLAUME DANIEL DELPRAT, in British patent No. 26,279, Nov. 28, 1902, described a process of flotation that consisted in immersing the ore in a hot but not boiling solution (of specific gravity 1.4) of salt-cake, or a solution (of specific gravity 1.4) of sodium sulphate and sulphuric acid. The ratio of sodium sulphate to sulphuric acid was 2.5 : i. The sulphides in the ore, he says, floated at the surface and were removed by a stream of water or by skimming.
ARTHUR EDWARD CATTERMOLE, in British patent No. 26,295, Nov. 28, 1902, described a process of oil-concentration in which he made use of the idea of oil-selection. His method of procedure is not made plain in his patent, but seems to be about as follows : To a freely flowing pulp he added from 4 to 6% of oil, and 2% of soap, the amount depending on the metallic contents of the ore, his object being to produce granules of sulphides of a certain size. For slimy ores he added a portion of coarser sulphide particles to serve as nuclei for the formation of granules, and effected the separation by an upcast current of water, taking the gangue off the top, and the granules at the bottom. For ores containing small amounts of mineral he added a portion of oiled pumice or oiled charcoal to serve as nuclei and removed the granules so made by flotation. After the concentrate had been secured, the oil was recovered by treating the oiled sulphides with an alkali, thus dissolving the oil and making it available for use again.
ARTHUR EDWARD CATTERMOLE, in British patent No. 26,296, Nov. 28, 1902, described a process of classifying mixed sulphides after they had been removed from an ore by his oil-granules concentration process. He accomplished this classification of sulphides by fractionally dissolving the oil of the granules in alkaline emulsifying agents of varying strength and activity. He first added to the oiled concentrate, with agitation, an alkaline solution that had a strength just sufficient to dissolve the oil from the sulphides having the least adhesiveness for the oil. This sulphide of least adhesiveness for oil was freed from the mixed sulphide granules, and was removed by an upcast of water or other suitable device. An alkaline solution of greater strength was then added to the remaining portion, with agitation, and the oil was dissolved from the sulphide having the next second adhesiveness for oil. This second sulphide was released in the same way as the first ; and so the process was repeated as often as was necessary.
GUILLAUME DANIEL DELPRAT, in United States patent No. 735,071, Jan. 2, 1903, described a process whereby flotation of sulphides is secured in a nitric acid solution. GUILLAUME DANIEL DELPRAT, in United States patent No. 768,035, Jan. 2, 1903, duplicated British patent No. 26,279, Nov. 28, 1902.
ALEXANDER STANLEY ELMORE, in British patent No. 184, Jan. 3, 1903, described an improved apparatus for oil-concentration wherein air was excluded from the operation. His method was substantially the same as that described in his previous patent, and that of Francis E. Elmore, except that by sealing all open vessels with a ring or surface of oil, the operation was performed in such a manner as to prevent the introduction of air into the pulp and thus prevent the possibility of oxidation of the minerals. He also describes two methods of removing the concentrate from the oil, one by heat and one by filter-press treatment. He calls attention to the necessity of cooling the oil after heating, presumably for the purpose of maintaining its viscosity and to prevent emulsification.
JOSEPH BARTON SCAMMELL, in United States patent No. 770,659 Jan. 31, 1903, duplicated his British patent No. 15, 280, July 9, 1902.
GUILLAUME DANIEL DELPRAT, in United States patent No. 763,662, Mar. 9, 1903, described a new form of apparatus for the application of his processes described in United States patents Nos. 735,071 and 768,035, Jan. 2, 1903.
