US22679A - Improvement in the manufacture of white lead - Google Patents

Description

B. F. SMITH.

Manufacture of White Lead.

No. 22,679. Patented Jany 18, 1859.

U NITED STATES PATENT OFFICE.

IMPROVEMENT IN THE MANUFACTURE OF WHITE LEAD.

Hpeeiliealion forming part of [letters Patent No. 22,679., dated January I IRSJ.

lie it known that: I, lhcNJAMtN l SMITH, of New York, in the county and State of New York, have invented new and useful Improvements in the Manufacture of \Vhite Lead; and I hereby declare the following to be a full, clear, and. exact description thereof, reterence being bad to the accompanying drawing, which forms part of this specification, and which represents a vertical section of an arrangement of apparatus for carrying into ell'ect my invention.

My invention relates to the manufacture of white lead according to the dry process," in which metallic lead under the inllnenec of heat and moisture is oxidized and combined with earl )Ullltj acid when exposed to the action of acetic vapors or vapors from vinegar; and my invention consists in a peculiar disposition of the lead in the convertingchamber, insuring its elleclual exposure to the corroding notion of the said vapors; and it further consists in the manner-of extraet ing from said chamber the carbtmate formed therein pre viously to subjecting it to the washing and drying processpvherelly the work men engaged in such mannfaeture are proteeted against the injurious efl'eets attendant. thereon when conducted aoeortling to previous modes.

'lo distinguish my invention from precedin methods, I would state that the ordinary process as practiced in Holland, France, and England consists in tirst placing, rolled lead sheets spirally arranged in low pots containing vinegar and wine lees. .lhesc pots are put into chambers dug in the ground and surrounded with hot-settling, by which arrangement a temperature of about 50 centigrade is produced, the same being necessary to effect the corrosion of the metal in about six weeks. The horse-dung answers a double purpose namely, that of producing heat and that of fnrnishingbyitsdecomposition carbonic acid. After this exposure the lead sheets are taken out of the pots and unrolled,when the carbonate formed from the lead crumbles in pieces, and is collected to be broken between wooden rollers and afterward ground and mixed with water, and the pastysubstanee thus produced placed in molds, where it remains three or four days, is dried, and sold in cakes. Besides the enormous expenditure of time, labor,

and apparatus incidental to such method of manufacture, said process is most prejudicial to the health of the workmen engaged in earryine; it out, particularly that portion of it which relates to the detaching of the carbonate ol lead from the metallic sheets. 'lhese sheets are required to be shaken and tapped to detach adhering dust and powder that form a considerable and valuable portion of the product. Such powder, being very light, forms a floating cloud, which the workmen necessarily breathing they inhale a deadly poison. I am also aware that by theAnstrian method of manufacture the lead sheets are hung over eross bars in ehambers. in the bottom of which vinegar-and wine lees areallowed to evaporate to ell'ect the corrosion of the sheets. These chambers are heated by horse dung, that supplies also the necessary carbonic acid, or by steannpipes or hot-air ilues surrounding,- said chambers. The sheets tints corroded are considm'ably incre: sed in thickness and contain a large quantity of. acetate of lead, which has to be detached and the carbonate carefully and repeatedly washed. Both of these ln-iellyaleseribed processes are expensive and dan rermls to the health of the workmen. In the former n'oeessagreat quantity of metallic lead remains as a residuum ol' the manufacture, and this requires to be remelted, while in the latter process the production of acetate of lead is so great that it may be detached in perfect crystals hanging about and around the sheets.

My improvement, as will appear from the following (lOSttL'lPllOll, obviates the defects before mentioned as incidental to either of the processes just described.

'lhus I first prepare in any convenient manner the lead in small spangles of (say) two inches in length, one-fourth of an inch width, and of the thickness of ordinary letter-paper (more or less) arched in their eross-section and ofarched or irregular form longitudinally, such as would be formed by melted lead issu ing from a line oritice and falling on a rap idly revolving" corrugated cylinder, cooling and breaking the stream and throwing the lead oil? in detached pieces. These spaugles I pile or throw upon racks placed successively under said revolving cylinder. The racks may be made of trellis-work and about;

lour hundred of them be used in each eon verting-rhainller, which chamber may be about six leet high, twelve feet long, and six feet wide, and should he made with an inclined bottom, as shown in theaccompanying drawing. lh racks d l place in said chamber in double rows byarrangingthem first. in the rear and piling them up to or nearthe top, and gradually advancing to build up a row or rows of other racks in front of them. The chamber then containing the racks with spaugleson them isearelully closed and lnled.

'lubes or pipes .r j/ are provided in the chamber at its bottom, establishinga communication between said chamber and a boiler or vinegar tub li,thetnbesbeing closed when rctlllllCt'l by trap-valves r 1'. At or near the top of the chamber is an opening I), closed by a trapwalve which is occasionally lifted to allow foul air to escape-that is, air which was in the tube and chamber previous to commencing work, and which, being lighter than carbonic acid, will rise and be expelled, said opening also serving to increase the circulation when the chamber is too densely filled and choking of the passages orobstruction is produced by means of a force-pu mp or seetion-blower applied thereto to effect a forced circulation.

I would state here that it may be advair tageous to combine the manufacture of white lead with thatof vinegar. The vapors rising from the fermenting-tub in the latter manufacture may thus be made available and collected and forced into the convcrting-ehamher A, and by arranging the said chamber above or on a level higher than the outlet to the vapor from the fermenting-tub the natir rat ascent of the vapors will cause them to enter the chamber. Such combination ol manufacture, however, 1 do not claim,as it is in common use abroad, and has been described in printed publications of date long prior to this proposition of such economy. Thcchamher A, 1 also provide with pipes or, entering at the top and serving to conduct the carbonicacid gas into the chamber simultaneously with the corrosion of the lead by the acetic vapors. It will be apparent that by this arrangement the most perfect circulation is produced, the carbonic acid gas descending, while the acetic vapors ascend among and through the several racks on which the spangles rest, and which, filling the chamber or thereabout, admit of no t-h rough-curren t in one direction more than another, but cause the gas and vapor to worn1"v their way in and among the spangles,and,as due to their arched orirregular form and thinness, to act with perfect equality, certainty, and effect in converting the lead as required. The distribution of the lead span gles on the racks may be from one to two inches in depth each successive series of racks or frames, which allows of the fumes from below readily, but not too readily, passing through the mass to the top of the chamber, where the foul air may escape. In all other llletlunls the lead is arranged with so much vacant space intel'vcningthat the fumes are at liberty to circulate where they tind the largest. drafts, and the consequent result. is very unequal eorrositjm ol' the metallic lead. The lead in s 'iaugles thus acted on in a pen l'eet, regular, and equal manner, or there about, by the acetic l'nmes is soon converted into a sultacetatc olf lead, which in turn is decomposed by the action of the carbonic-acid gas freeing the acetic acid that is again made available for further action on the metallic lead, and which process is being continually repeated. In from live to ten days the lead spangles l )CCOlllt) by this treatment thoroughly corroded, leaving in the chamber, instead of metallic lead, pure carbonate of lead intermixed, but only slightly, with acetate of lead, which is converted by an after process into carbonate of lead; or the product from the chamber maybe freed from the acetate of lead by repeated washing.

The chamber being filled. with the converted product that is, carbonate of lcad-I proceed to extract it from. said chamber as follows: A pipe at (shown in the accompanying drawing) is made to convey from a boiler or tank steam or water into the chamber. \Vhen steam is used, I introduce a. jet of it, the object of which is to saturate the carbonate of lead and so moisten it that the whole mass shall acquire a pasty consistency somewhat like mortar, and the said jet further serves to expel the foul gases and air contained in the chamber, and wl1ich,being specifically heavier, will be displaced and fall in the lower part of the chamber, from which they may escape by lifting a trapvalvc. In this way the workmen are safely guarded against the obnoxious dust and vapors which according to previous methods they have been forced to inhale while removing the lead from the chamber to the washingtub.

When the pipe d last referred to is used to convey water, I make or attach it as a hose, in order that it may be moved or worked from the outside of the chamber in such a manner as to project its jet or stream in every direction within the chamber. In this case the washinglub is placed immediately under the outlet of the chamber, and the carbonate of lead is washed out of the chamber without much delay or dilficulty and entirely by reason of the inclination given the bottom of the chamber, whereby all handling for transfer of obnoxious matter to the washingtub is avoided.

W hat I claim as my invention, and desire to secure by Letters Patent, is

l. The manner of filling the chamber with metallic lead by means of the open-work tables or racks on which the lead in detached pieces rests, arranged one above the other in successive and close series, substantially as described, and whereby a more thorough and equal circulation of the fumes or gases among the lead is produced.

L. ('oustrueting the eourertiug-vhzuuber other iueitlcutnl products previous to their with an inclined bottom,substantiallyas and extraction from the eonvertiug-vluuuher to for the purposes set forth the notion of steam, substmltinlly in the man I 'lhe method herein described ot' extra-tit uer and for the purposes specified. in; from the eonvertiugrhuuiber the wax-hon In testimon whereof I have siguml my auto of lead. mul other ineit'lentul products by name to this speeitimrtiou before two sul means of a current or currents of water pausserihiug' witnesses. ing through said chamber from top to bottom, substantially in the manner and for the oh- Witnesses: jeets herein set; forth. 1 A. POLLAK,

4. hubjeoting the enrhouztte of loud and i \VM. 1). RUSSELL.

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