US147454A - Improvement in separating silver and gold from lead - Google Patents

Description

ZSheete--SheetI4 [L P. WEBSTER, C. C. LEWIS &. A. P. WEBSTER.

Separating Silver and Gold from Lead.`

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Patened Feb. 10,181741.

UNITED STATES PATENT EEICE.

DAVID l. VEBSTER, CHARLES C. LEXVIS, AND ALMAR I). VEBSTER, OF NEWT vonk,

IMPROVEMENT IN `SEPARATING SILVER AND GOLD FROM LEAD.

Specification forming part of Letters Patent No. 147,454, dated February 10, 1R74 application tihd January 9, 1874.

. CHARLES C. LEwrs, and ALMAR I. WEBSTER,

of the city, county, and Stat-e of N ew York, have made certain new and useful Improve Vments in the Arts of Extracting Silver and Gold from Lead, which have not been used or known previous to our invention.

By our improvement, we are enabled to effectually desilver the same weight of metal in one-third less time, and at one-third less expense, than has heretofore been employed for the same purpose.

The following, with the accompanying drawings, is a full and exact description of the apparatus and process employed and practiced by us, which will enable others skilled in the arts of separa-ting silver and gold from lead to practice it.

Figure lis a double furnace having three kettles. The upper two kettles are thirty-three inches in diameter each, and eighteen inches in depth, made of castiron a half-inch in thickness, holding each two tons of melted metal. The lower kettle isforty-iive inches in diameter and twenty-four inches in depth. The furnaces are constructed of brick, with a cover of cast-iron, formed of two sections, each with a iiange of four inches projection for holding or binding the brick. The kettles have flanges about four inches in width, which rest on the cast-iron top plate, and thus form a tight'connection. At the right of the larger part, hav ing the two kettles, is a door, h, opening to the iire-boX, which reaches beyond the two kettles, and to a flue for carrying off smoke to the stack. At the left of the lower part, having one kettle, is a pit, e, for access to the door and nre-box of this part, for heating1 the kettle. This lower and larger kettle has the capacity for holding` four tons of melted metal.

Fig. 2 is an iron-plate disk a quarter-inch thick, and of diameter corresponding to the interior of the two upper kettlcs. This disk is perforated'by many holes.

The above constitute the apparatus for carrying on the first part of the process.

Figs. 3, 4, and 5 represent the apparatus employed for the second part of the process.

Fig. 3 is a longitudinal section. of the furnace, showing theretort a and the angle at which it is set. .'.lhe arch d, Figs. 3 and 4, serves to shield the retort from the direct action of the iiame. The small iiues h h admit the flame and heat above the arch, and are located at the fourcorners ofthe furnace. The iire-box is indicated byf in both figures, and the ash-pit by g.

The retort is made, preferably, of east-iron, in the shape of a bottle, having attached to and cast with it, at its bottom, two pipes, as shown at b b, Fig. 3. The body of the retort is cylindrical, two feet diameter outside, and two feet nine inches long between the points where the contraction is commenced. The mouth or neck is nineteen inches long and eleven in diameter. are fourteen inches long each, and four and one-half outside diameter, making the whole length Iivc and one-half feet. The uniform thickness of the metal is one inch.

Fig. 4 is a cross-section of the furnace, in which the arch is more plainly shown at l than it is in Fig. 3. The furnace is built of fire-brick, stayed and braced by iron bands and rods, as is usual in the construction of like furnaces.

Figisa perspective view of the furnace, showing the mouth end of the retort and part of the kettle at the opposite end c, for collecting the melted metal when allowed to run from the retort. The outside dimensions of this furnace are ve feet ten inches long, five feet wide, and four feet ten inches high. The walls are nine inches thick. The retort within the furnace rests upon piers of tire-brick built upon the arch. The two necks or pipes at the lower end of the retort are provided so that, when the one on the side placed nearest the iire becomes defective, it may be turned uppermost, and thus the retort is made to last much longer than if only one pipe were provided. '.lhe upper pipe is always kept closed.

The first step in the process for extracting the silver or gold from lead is practiced as follows: For example, if the lead to be operated upon contains two hundred ounces of silver to the ton, we put two hundred and forty `pounds metallic zinc in the bottom of each of the upper kettles a a, Fig. l. Over each of these we The pipes at the bottom f ing this time the metal is heated considerably above the degree of its melting temperature,r and stirred during forty-five minutes.

dross is next skimmed oi' at intervals of aboutk The ten minutes, during an hour longer, when the lead is drawn off by withdrawing an iron plug, b b, by means of a screw and iron rod passing to the bottom of the kettle through the melted metal. It is collected in the lower kettle, and from this cast into pigs. The dross thus formed and now containing the silver and zinc with some lead, is put into the retort (a, Fig. 3,) and melted. The lead is drawn oii' at the small pipe b to the'kettle C then, after stopping` the pipe, one thousand pounds of bullion or lead 4containing silveris passed into the retort with neck ormouth of the retort should be kept closed by inserting` the bottom of a plumbago crucible into it as much as practicable, iny order to exclude atmospheric air. f 1u the kettle C, now free from silver, is

The lead cast into pigs. The rich dross containing the silver remaining in the retort is next removed and placed on an iron plate, and while hot it is granulated. The granulated dross is next put into bottle-shaped plumbago retorts arranged in suitable furnaces, and the zinc distilled and collected in the manner de'- scribed in technical works relating to the metallurgy of zinc. lead leftin the plumbago retorts is next cast into ingots, and finally yplaced on the cupel in the cupel-furnace and there relined.

We would here remark that we prefer a cylindrical retort, as described and represented in Fig. 3, for obvious reasons; but other forms might be used, provided such were constructed with a small mouth, which could be readily kept closed, so as to exclude the access of air during the greater time of the treatment.

Having described the process involving our improvements, whatwe claim as of our invention, and desire to secure by Letters Patent of the United States, is f 1. The perforated iron disk for holding the zinc to the ybottom of the kettle until the lead is melted, and then causing it to be distributed through the metal above, so as to come in contact with and take up the alloyed silver. y

2. The combination of furnaceand inclined retort, substantially as described, and for the purpose set forth. j

k3. The treatment of the skimmings or dross in a closed retort, substantially as described.

4. The treatment of the silver dross in a f chamber in which the air is so highly rareed that it has little or no oxidizing etfect upon the zinc, substantially as described.

5. The concentrating of leadk dross containing silver, derived from treatment of lead by any of the usual processes, in a closed retort or chamber from which the air is excluded, substantially in the manner described.

DAVID P. WEBSTER. CHARLES C. LEWIS. ALMAR I. WEBSTER.

In presence of- J. O. NoxoN, l). D. PARMELEE.

The silver and remaining

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