US998665A - Refining metals. - Google Patents

Description

. C. ARSEM.

REFINING METALS.

APPLICATION FILED PEB. 9,

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WELLCII 0..RSEM, Old SCHENEGTDY, NEW YORK, SSEGNOE T0 GENERAL ELECTRIC coureur, s! conronurron or new voren.

REFINNG METALS.

bpecncution or Letters .tatent.

Patented July 25, i@llll.

Application led ."Eebruery 9, 1910. Serial No. 2,933.

monly mode the snode in the electrolytic cell; the silver is deposited on the cathode, and the goid, together with platinum and other associated metals, falls to the bott-om oi the cell as slime or mud. This mud must then be melted and subgected to hirt-her y purification es by electrolysis in order to sepurete the gold from the associated metals.

i have discovered that it' the above mentioned metals are subjected to a i'Il-CD distiiiation in s nearly perfect vacuum, a sharp `distinct sepsrstion or the silverand gold con be obtained, thereby avoiding the complications and expense incident to getting the motels into soiution and reiining them electrolytically. l find that silver con be completelydistilled from an alloy by heating the slloy to a temperature ot about i300 C. in s, nearly complete vacuum.

Vlin the type ci iurnace to be hereinafter described a pressure as low es about imillimeter of mercury or even less can be readily obtained. 'lhe gold can be separated subsequently from platinum or other retractory metals by raising the temperature to about 1500o C. A .furnace whereby my process ci separating these metals can be carried out -is shown in the accompanying drawings '.tihis furnace, however, forms no port ci my present invention, and is claimed .by me in s copending application, Serial No. 513,407, tiledltug. 18, 1909. 'lhe furnace has a heating chamber in which the sl-` loy can be raised to the requisite tempereture and also a condensing chamber in which the distilled product can bek collected.

` ln.- these drawings, Figure 1 is a sectional elevation of the furnace, showing1 the heet ing element, the crucible and its charge being removed from the urnace; Fig. 2 is o sectional pien view ofthe furnace; and Fig. 3 is an end elevation oin the same part-1y in section.

The main envelop of the furnace consists or a rectangular box' 1, preferably of gun 'metal with a coating of tin, provided with a cover 2 bolted securely in place. rlhe cover 2 has manholes 3 and Il located respectively above the cold and the hot zones of the furnace. Lead gaskets 5 can be used under the Icovers to malte air-tight joints.- The heating;r element ot the furnace consists of tour graphite grids 6, 7, 8 and '9 sswed transversely, and with their corners rounded ed, as shown in the drawing, so that when current is passed through them they will attain a uniform incondescence throughout substsmtially their entire iength. Current is supplied to these graphite resistance elements by way oitl water-cooled copper tubes 10 end 1i passingl through insulating bushings in the end of envelop 1. rlhe tubes are clamped, respectively, in copper blocks 12 and 13, which in turn are bolted to the graphite grids `0 and 9. -The other ends-oi these grids make contact respectively with the graphite blocks lli! and 15 which make electrical connection with the lower pair oi` grids. cross connection 16 of graphite at the end ot' the lfurnace completes the electrical circuit. For the sake oi avoiding con- .:tusion on the drawing, the current suply cables for the tubes 10 and l1 have neen omitted but the rubber hose for conducting' Water to these terminals :for cooling puivposes is shown at 17 and 18.

The above described heating element con sisting of the tour grids. 6, 7, 8 and 9 is inciosed in a rectangular heat insulating screen, the graphite walls of which ere mede double throughout with an intervening pecking' of graphite. The bottom member .19 of the screen rests on insulating buttons 20ct lave4 and supports the end walls 21 ond 22 and also the side walls 23 and 24. '.ihe top member 25 lrests on the tops 'of the four side well This heat insulating screen serves to limit the radiation of heat outward und serves to reiect and concentrate the heat on the'rectangular space inclosed bythe heater grids. Within this space may be introduced -a rect-angular crucible 26 of graphite containing the charge of olloy which may be assumed to consist of silver, gold and perhaps highly refractory metals, such as platinum. The Crucible may be conveniently supported on a rectangularv platF term 27 carried on graphite standards 28 distilled over from the hot zone.

`which leads to a vacuum pump.v

which pass down through holes in the. heat insulating screen and iterminate in insu-flating bushings 29. The crucible is prefer'- ably provided with a cover to prevent free escape of vaporized material except through the tubular outlet 30 which leads to the condensing chamber 31 at the other end of the furnace.

The condensing chamber mayadvantageously consist of an earthenware or iron pot fitting snugly against the water-cooled walls of the envelop 1 and of suliicient size to insure complete condensation of the metal The condensing chamber may be provided with a cover 32 preferably having an outlet 33 for the ready removal of air when the entire furnace is pumped out by way of pipe 84 ind it v'desirable to keep the vacuum pump in continuous operation so that the pressure of gases within the furnace may be kept as low as possible. The main envelop 1 of t-he furnace is maintained cool by the circulation of the water below and on all sides of it up to a level just below the man-hole covers 3 and 4. These are preferably left unsubmerged so that the charging and discharging of the furnace can be carried out without drawing off the cooling fluid and without any considerable vdismantling of the furnace.

When a charge of the above alloy has been placed in a Crucible 26, current is supplied to the heater grids until the temperature is about 1300O C.' At this temperature the silver is completely vaporized from the associated metals and passes over into the condensing chamber 31. This temperature is maintained for several hours, the actual length of time depending upon the amount of alloy in the furnace, a greater amount of alloy requiring a somewhat longer time to completely drive off the silver. After cooling, the furnace is opened by removing the manhole cover 4 and the silver is removed either by cleaning out the condensing chamber 3 1, or by removing it entirely from up to the gold is completely distilled and passes the furnace and substituting a similar condensing chamber.A If it is desired to separate' the gold from associated platinum, the manhole cover 4 is replaced, the furnace is again evacuated and the temperature is run over into the condensing chamber 31, a temperature somewhat higher than 1500o can be used to advantage, as there is little danger of volatilizing a refractory metal such as platinum until very high temperatures are reached, the gold passing over more rapidly at temperatures somewhat higher than 15000. After this heating has been continued for several hours, depending upon the amount of metal to be separated, the furnace is again allowed to cool down and the gold and platinum are removedfrom the furnace. Y I What I claim as new and desire to secure,y by Letters Patent of the United States, is,'--`

1. The process of separating gold and silver which consists in heating an alloy of these metals in an attenuated atmosphere to about 1500O C. At this temperature a temperature of aboutl-OOO C. to distil oif Y the silver.

2. The process which consists in heating an alloy of silver, gold and platin-um inan attenuated atmosphere at a temperature of about 1300CJ until the. silver is' completely vaporized and 'then raising the temperature to about 1500o to distil the gold.

3. The process of parting gold and silver which consists in heating an alloy containing these metals at a temperature of about 1300o under a pressure of about one millimeter of mercury.

4. The process which consists in heating a mixture of gold and silver in a substantial vacuum at the vaporizing temperature of the silver, thereby parting said metals.

In witness whereof, I have hereunto set my hand this 8th day of February, 1910.

' WILLIAM C. ARSEM.

Witnesses:

BENJAMIN B. HULL, HELEN Onronn.

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