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UNITED STATES PATENT OFFICE. GEORGE P. HULST, OF HAMMOND, INDIANA PROCESS OF TREATING LEAD BUILLION. 1,285,714. Specification of Letters Patent, Patented Nov. 26, 1918. Application filed March 20, 1918, Serial No. 223,573. To all whom it may concern. copper. The removal of the copper from the Be it known that I, GEORGE P. Hu LST, a bullion in the liquating step to the extent citizen of the United States, residing at here indicated, leaves the softening furnace Hammond, in the county of Lake and State in which the oxidizing step is conducted, 60 of Indiana, have invented certain new and free to operate on a practically decopperized useful Improvements in Processes of Treat charge, or one from which the harmful per ing Lead Bullion, of which the following is centage of copper has been eliminated. By a full, clear, and exact description, reference Subjecting the liquated decopperized bullion being had to the accompanying drawings, to oxidation in the softening furnace, th 85 0 forming a part hereof. impurities such as arsenic, antimony al In the refining of lead bullion by what is the like are separated in the form of a skim known as the Parkes process, the bullion is or antimony slag composed principally of first charged either directly into a softening lead antimony arsenic oxid (with 1% to 3% furnace, or thrown into kettles and melted of silica coming from the furnace linings), 70 5 down and then pumped into the softening this slag being subsequently treated in the furnace. The softening operation comprises antimony blast furnace for the production two steps, to wit, liquation and oxidation, of antimonial lead. In the present embodi- . the metals held in solution by the red-hot ment of the invention, the liquated decop lead being in a measure separated out in the perized bullion is subjected to oxidation in 75 liquating step, and metals alloyed with lead the softening furnace, preferably in the and more easily oxidized than lead, being presence of suitable oxidizing agents such as separated out in the oxidizing step. The the skim from the refining furnace (a lead impurities removed by the softening process zinc oxid), molding skim (a lead oxid), or (liquation and oxidation) are in the form skim from the pattisonizing kettles, the said 8) 25 of copper dross, and a slag or skim contain oxidizing agents materially hastening the ing oxids of lead, arsenic, and antimony with softening operation, their use resulting not Small percentages of copper and other im only in a better cooked charge but in a purities when present, and metallic shot lead greater direct output of lead as will herein bullion which contains silver and gold. This later more fully appear. A further object 85 30 slag is cooled down or dumped directly into of the invention is to remove from the anti the residue furnace. Usually there are two mony slag above referred to, all the mechan skims of the slag taken from the softening ically suspended lead bullion by Subjecting furnace, these being treated in the residue the skims from the softening furnace before furnace with a proper complement of coal their treatment in the blast furnace, to a 90 35 and lead sulfid ore giving a resulting anti preliminary treatment in a preheating fur mony slag free from silver which is subse nace without reduction with lead sulfid or , quently smelted with refinery skim in the coal, the preheating action (in which the blast furnace to antimonial lead; a hard temperature is raised to make the slag very lead bullion which is retreated (in the liquid) causing the bullion to drop and set 95 40 liquating kettles and softening furnace); tle out of the slag and carry down the silver and a lead copper matte which is sent to the and gold, the bullion being returned to the smelter and bessemerized. softening furnace. A further object is to The primary object of the present inven treat (in a blast furnace) the antimony slag tion is to dispense with the residue opera aforesaid in conjunction with outside lead 00 45 tion or treatment of the skims or oxids drosses free from silver, thereby producing aforesaid in the residue furnace, thereby good, clean, marketable antimonial lead, and effecting a material saving in the cost of eliminating the use of the residue furnace treatment of the bullion. To effect this sav for the treatment of the first and second ing however, care must be taken to segregate skimmings from the softening furnace as is 105 50 and remove from the charge of bullion in the now done under the old process. A further liquating kettle as much of the copper as object is to effect a material saving of zinc possible, or to such an extent that it gives in the desilverizing kettles, to reduce the no trouble in the later stages of the process. cost of retorting and cupel operations by In practice the copper should be removed segregating and removing the copper from O 5 5 from the metal in the liquating kettle to the bullion before the latter is charged into bring the bullion down to .05% (or less) the softening furnace. A further object is 32 1285,734: to treat the copper drosses from the liquat liquating operation the drossing of the cop ing operation, the copper skims from the de per is carried to the point where the bullion silverizing kettle, the copper litharge from in the kettle drops to .05% copper (the cop the cupels, and lead slag from the reducing per in the liquating kettle may even be low hearth, in the residue furnace with a proper ered to .03%), the object sought being to re 70 complement of lead sulfid ore (galena) with duce the copper content of the lead bullion a view of producing a lead copper matte, charged into the softening furnace to the dross bullion, and a slag free from silver lowest possible degree so as not to interfere (and copper), said slag going to the blast with the desilverizing operation later on. The 0. furnace to be treated in conjunction with the antimony slag from the preheating fur lead in the liquating kettle, after thorough 75 nace, for the production of antimonial lead drossing or skimming off of the copper dross the dross bullion being liquated or returned is pumped into the softening furnace (rever to the liquating kettle, and retreated in the beratory) where the lead is subjected to softening furnace, and the matte subse oxidation (by air) preferably in the pres quently bessemerized. In the old process ence of suitable oxidizing agents added to the copper skims from the desilverizing ket the charge to hasten the softening operation. tles went to the softening furnace, an objec In the present embodiment of the invention tion avoided by the new process, the presence these oxidizing agents comprise (1) refiner 20 of copper in the softening furnace not being skim which is a lead zinc oxid, the oxygen E. constituting as it does an interfer of the oxid taking up arsenic and antimony 85 ing element in the later desilverizing opera and dropping lead to the extent that the tion. A further object of the invention is arsenic and antimony are taken up in the to effect by proper treatment on a reducing slag, the presence of the zinc which goes into 25 the slag materially reducing the lead content hearth, a partial reduction of the litharge of the slag and therebv increasing the direct 90 coming from the cupels and to return the output of lead; (2) molding skim which is high grade metal thus produced to the cupels a lead oxid; (3) Pattison skim (a lead oxid); for retreatment, the resulting lead slag be or (4) impure lead oxids derived from ing charged into the residue furnace for the other or outside sources may be used. Where 30 recovery of any copper in the form of lead refiner skims or equivalent oxidizing agents copper matte. The advantages of the new are employed in the softening furnace there process will be readily apparent from the is no occasion to blow air into or stir the following detailed description in connection mass, but merely bring the heat up to slag with the accompanying drawing in which ging temperature. The resulting slag is 35 The figure represents a flow sheet of the 100 several steps involved in the new process. principally a lead antimony arsenic oxid in The various instrumentalities employed in which a considerable portion of lead bullion carrying out the successive steps of the proc is held mechanically or in suspension, the ess are fully designated on the flow sheet bullion carrying silver and gold. To re 40 so that a reference thereto may be made lease this bullion the slag is skimmed from without the necessity of identification the metal in the softening furnace (there thereof by reference letters or numbers as are two skimmings) and charged into a pre will be clearly apparent from an examina heating furnace or settler in which the tion of the flow sheet. Some of the indi mechanically held lead bullion is dropped, vidual steps involved in the new process are the preheating of the slag causing it to be old per se, and to these I make no claim, the come very liquid thereby releasing the lead 10 novelty of the process residing in the se bullion which is returned to the softening quence of steps by which the several objects furnace. The preheating furnace is fired above enumerated are attained.