USRE12105E - Archibald drummond garmichael - Google Patents

Description

- UNITED STATES- PATENT OFFICE.

ARCIIIBALD DRUH'MOND CARMICHAEL, OF BROKEN-HILL, NEW SOUTH LES. AUSTRALIA.

. DESULFURIZINO SULFID ORES.

MCLTIOI forming Patent No. 12,105, dated April 81, mos.- t

Original R0. 70590. dated July 29, 1903- Applieet'lss forreissue Ilcd larch 3,1903. Serial Io. 146-029.

To all whmn it may concern.

Beitlruown that I, ARCHIBALD Damnson CARMICHAEL, lnetallurgist, a subject of the 1 King of Great Britain, residing at the Royal Hotel, Argent stl eet, Broken Hill, in the State of New South Wales, in the Commonwealth of Australia, have invented certain new and useful improvements in the Desulfurizing of Sulfld Ores Preparatory to Smelting. ofwhich the following is a specification.

-The invention relates to the treatment of sulfld ores ormetallicsultids, mattes,or metallurgical products preparatory to smelting, and more particularly to the treatment of lead sulfid ores and other metallic sulfids, such as sulfide 0t zinc, copper, or iron and mixtures of the same. its object is to desult'urize and cinerate such ores or products and to change them into a condition more suitable for the smelting process. In the processes hitherto employed such ores or products have first been subjected to a preliminary roast in a suitable furnace, with or without; suitable chemical reagents, for the purpose of oxidizing or sulfating the metallic sulfids. The charge has then been removed to a con verter or other suitable receptacle, where it has been subjected to an induced current of air for the completion of the oxidation.

My invention consists, essentially, in dispenning with the preliminary roasting and in the complete desulfurization and ciueratiou of the sulfide in the converter in one operation. I accomplish this by,mixiug with the raw sultld ore or metallurgical product's suitable proportion of calcium sulfate aud bysubjecting the mixture in a converter to the action of an induced current of air, starting the reactions'by means of heat, whereby sulfate of the metal and calcium snlfld are produced, and the calcium sulfid in its oxidation produces sufllcient heat to set up the necessary desulfurization reactions and to thor-Q onghly oxidize and cinerate the ore without loss by volatilization.

In the place of calcium sulfate I mayemploy gypsum or sulfid of calcium where the latter can be obtained at lesscost as a waste product in such'as theLeblauc alkali process. Where gypsum is employed, it maybe found desirable to subject'it to a dehydrating pm ess before employing it in the converter.

In my invention I first intimately mix withthe sulfid ore or product a definite percentage ofcalcium sulfatenrcalcinm sulfid orgypsum. Thepert-entage required may be from ten to thirty-five per cent, according to the grade of are under treatment. The mixture is fed into a converter and gradually heated externally until the lower portion of the'charge say one-third to one-fuurth--attains a dullred heatof, say, about four hundred degrees (400) centigrade, or in lieu of this the reactious may he started by throwing into the empty converter a shovelfui of glowing coal and turning on a small amount of a r sufll-' cieut to-lreep this burning and then ceding the charge on top of the coal. This heating results in the partial conversion of the me: tallic sultld to sulfate and a corresponding reduction ofthe calcium sulfate to calcium sulfid-this in, say, the'case of lead-accordiug to thefollowiug equation:

thus regenerated for renewed use according In to the following equation: M cas+i4o=caso,, -and in such exothermic chemical reaction suliicieut heat is generated to complete the desulfnrizat-iou' of the, charge by the concurrent reactions set up by the metallic oxids and sulfates produced by the calcium-sulfate salt on fresh or undecomposed portions of the original charge of orestufl, as hereinafter de- ,a

scribed. The calcium sulfate being regenerated is free to reset on a further definite portion of the nndecomposed original charge of orestnfl or metallurgical product with a similar result as that before described, and these 5 alternating reactions occur until uearthe end of the treatment. Concurrently with the sulfatiziug of the metallic 'sulflds by the calcium sulfate and the reduction of the sulfate of calcium to sulfidof calcium and its regeuera scutperatnre of the masshas reached about a In the presence of the induced current of air which is permeating themass the metal so formed is oxidized and in this state reacts on a further portion of the produced metallic.

sulfid with an increased formation of metal and evolution of sulfurous acid accordingto the following equation in the case of lead:

The metal so produced in this last reset ion is wholly or partially reoxidized from-the oxygen ofthe air-cu rrent and, being free to react on still'further portions of the metallic snlfld repeats the reaction and become'san important factor in the desulfurizing of the nudecomposed portion of the charge of orestufi. As the desulfurization proceeds and the sulfate of metal accumulates reactions are set up between the metallic sulfid and different multiple proportions of the metallic sulfate with theformation of metal metallic 'oxid and evolutibn of snlfurous acid, as shown, as follows: 7

with two molecules-of metallic sulfateto one molecule of metallic sultid in the caseof lead according to the following equation:

with three molecules of metallic sulfate, to one of metallic suliid in the case of lead according to the following equation:

Ph.S+3Pb.SO,=-1Pb.O=l-4SO,. At this stage of the desulfurization the temmaximum,a considerable shrinkage has taken place, and the mixture has a tendency to becalcium sulfate into come pasty. This becomes more marked as. the production of metallic oxid predominates,

and as the desired desulfurization-poiut is attained the mixture fuses toa mass of metallic .oxid in-conjunction with the gangue of the ore or ores under treatment. At this fusion stage the sulfid of calcium produced from the 1 to the difficulty of coming into actual contact with the air in the pasty mass, but being subjected to the strong oxidizing action of the metallic oxids produced results in the formation of a plumbate of calcium and evolution calcium sulfate cannot readily oxidize, owing of sulfnrous acid. The mass, consisting of metallic oxid and plumbate of calcium, then cools aud'cinerates as the exothermic action ceases and can be readily'removed to a blastfurnace for smelting for the recovery of the metals.

Though my invention is.described'more particularly with reference to lead sullid ores containing zinc, such as are commonly known as the Broken Hill sulfids, I wish it to be clearly understood that my process may-be equally applied to other classes of sultid ores, such as copper sulfide, &c.

Having thus described my invention, what I- claim as new therein, and desire to secure by Letters Patent, is-' 1. The process of treating mixed sulfld ores,

which consists in mixing with said ores a suifurcompoundofametalofthealkalineearths, starting the reaction by heating the same, thereby xidizing the sullid and reducing the sulfur compound of the alkalimetah-and passing a cu'rrentof air to oxidize the reduced sulfur compound of the metal of the alkalies,

substantially as and for the purpose set forth.

2. The process'of treating mixed sulfid ore s,. i which consists in mixing calcium sulfate with sai'd ores, starting the reaction by means of oxidizing the sulfid ores, liberheat, thereby ating sulfurous-acid gas and converting the diziug the calcium snlild to sulfate, substantially as and for the purpose set forth. I y

- AIOIIIBALD DRUIIIOND ihikillCllABlt Witnesses: Y 4

Exams STANLEY BURGESS, Cranium Amman- HACK.

calcium sulfid and oxi--