US1283782A - Process of roasting ores. - Google Patents

Description

w. A. l-NGHAM.

PROCESS 0F ROASTING GRES.

APPLICAHON FILED FEB. 2l. 191,8

l 283,782. Patented Nov. 5,1918'.

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.narran srafrns PATENT OFFICE.

WILLIAM A. ING-HAM, OF LOS ANGELES, CALIFORNIA.

lEROCJESS 0F ROASTING DRES.

Specification of Lette'rs Patent.

Patented Nov. 5, 1918.

Application led February 21, 1918. Serial No. 218,462. l

To all wwm it may concern.'

Ble it known that I, WILLIAM A. INGHAM,

a citizen of the United States, residing at Los Angeles, invthefcounty of Los Angeles and State of California, and useful Improvements in Processes of Roasting Orcs, ofwhich the following is a specification.

' My invention relates to a process of reducing ores.

It is an object of this inventionv t0 treat ores, especially sulfid ores so as to volatilize form a. part of this specification, I have Fig',

illustrated an apparatus used in connection' with my process, and in which:

,Figure 1 is a horizontal section on lines i -l-1 ofFig. 2.

Fig. 2 is a vertical section on line 2 -2.vof Fig. l.

Fig. 1. v v

Fig. 4 is a vert-ical section on line 4 4 of 1, showing the bearings of the rotating table.

In the drawings, 10 indicates an annular furnace 'chamber surrounding ,a vertical v stack or chimney 11 to which the same is connected by means of two oppositely arranged Orts 12 and 13.l 1 4 and 15 are vertical ba e walls extending from opposite s ides of the stack 11. 16 and 17 indicate burner nozzles arranged at opposite sides and on the outer periphery of the furnace chamber 10. 19 is a rotary roasting table annular in shape and strengthened by reinforcing radial ribs 19 on its under side. The table 19 is provided withrollerS 20 adapted t0 travel on a grooved track 21 suitably secured to the stack 1l. The outer end of thel table is provlded on its under side with a rack 22 adapted-to engage a series of pinions'23 mounted in suitable bearings 24 supported I' on the outer Walls'of the furnace chamber 10. 25 is a circularasbestos board adjacent to the outer end of the rotating table 19 and on the .under side thereof, and adapted have invented new- Fig. 3 is a vertical section on line 3-3 of' to keep fuel and waste gases from passing from the furnacechamber 10 past the rack .22 into the roasting chamber 26. 27 4is a vmetal plate extending upwardly from the 'outer wall of the furnace chamber and formling the outer wall of the roasting chamber 26. 28 is an angle iron suitably fastened to '29' projecting inwardly andabove the outer -edge of the roasting table 19. This flange ed on a shaft 33 and disposed in a' water cooled casing 34. The rotary cylinder 33 forms with the wall of the hopper 32, adjacent thereto, a narrow feed slot The ends of shaft 33 are mounted in movable bearings 50 whereby the cylinder 33 may be moved in relation to the hopper 32 to adjust/'the width' of the'feed slot 35. Power is transmitted by means of a pulley '36 connected with any suitable source of power, and secured to a drive shaft 37 suitably mounted. 38 is a gear 'Wheel fast to shaft 37 and in mesh withy idler gear 39 which in turn meshes with gear 40 mounted on shaft 41 securedl to 'feed roller 3 3. On the inner end 0f shaft 37 a gear 42 is mounted which is in mesh with a drive gear 43 engaging the rack 22 fast on the roastingtable 19.

are mounted, are supportedy by a vertical.

partition wall 53 of refractory material, exf tending from the top 30 'of the roasting chamber 2G lEhe outer peripheryv of the roasting cham- The lower ends of the walls 53 exe` tend within a fraction of an inch of the the wall 27 and forming a horizontal fianfre and froml the chimney 11 to f roasting table `19, allowing just sufficient l clearance for the layer of oredeposited -on ing devices 31 adjacent thereto, and serve to scrape the treated ore from the roasting table 19 into an ore residue chamber 45.

The ore to be treated is ground to about lifty mesh and depositedin a thin sheet by means of the ore feeding device 31 on to the roasting table 19. The degree of thickness of the layer of orc deposited on the roasting table 19 may be controlled lyeither increasing or decreasing the speed of rotation of the roasting table 19 or increasing* or decreasing the .amount of ore through .the ore feeding device 31 by adjusting the width of the ore feeding slot 35. The roasting table 19 is heated to a temperature sufficient to volatilize the metal sultid during its travel from the ore feeding device to the first set of ore residue cleaning' rods 44 that it encounters. I have found. that in cases where the thickness ofthe layer of ore is 1/192 of an inch and the length of the layer 72 inches, the metal sulids are completely volatilized in a roasting period of six seconds before they encounter the cleaning rods 44 that remove the residue of the ore from the table 19 on to the scoria chambers 45. The metal sulfid vapors due to their own expansion, pass through outlet passages 46 arranged immediately above the burners 17 andare brought in contact with air entering through a conduit 47 which will convert the metal sulfid into the metal oxid and sulfur" dioxid, which are separated from each other by the usual methods.

It should be noted that with the exception of a small quantity of air which enters the roasting chamber 26 with the ground ore through the ore feedingr device 31, the roasting of the ore takes place under the exclusion of air within the roasting` chamber 26. By reason of the fact that the layer of ore on the roasting table is exceedingly thin, which is preferably to a degree in which the ore particles are separate from each other, the metal sulfids are completely volatilized and the rabbling of the ore required in the usual roasting process is dispensed with in my apparatus, as no sintering or fritt'ng of the ore takes place, no oxide being formed within the .roasting chamber, except a negligible quantity due to the air admitted 'with the ground ore. By my process, the volatile metallic contents of the ore are completely extracted.

In the old processes, in which ore is roasted in the presence of air, it is necessary to rabble the ore to expose all the particles of the ore to the air for oxidation. This rabbling is entirely dispensed with in my process, since it depends upon the vol-atilization of the metal, thus avoiding the rabbling and the loss of the ore that is carried away in the form of dust. Furthermore the volatilized metal subsequently recovered in the state of an oxid is in a substantially pure state uncontaminated with ore dust.

l have intended my process principally for the roasting ofores containing suliids of arsenic and antimony. It is obvious how'- ever, that the same may be applied to ores containing metallic compounds which may be volatilized under the condition existing in the ordinary roasting furnace. My process is especially valuable in connection with gold and silver ores containing sulids of arsenic or antimony. As well known, gold ores which are to be treated by the cyanid process are penalized if such ores contain sulfid of arsenic or antimony. By subjecting such ores to preliminary roasting treatment in accordance with my process, the objectionable antimony and arsenic compounds may be easily removed.

My process is a simple one and needs little supervision or technical skill in operation. The apparatus is simple, and worn out parts may be easily replaced. Furthermore the contamination of the ore and ore products by the furnace gases is avoided.

Various changes in the steps of the process and in the construction of the roasting furnace may be made without departing from the spirit of my invention, as claimed.

I claim:

l. A. process of treating ores containing antimony sulfids, comprising heating a thin layer of the ground ore in a closed roasting chamber to a temperature sutlicient to volatilize the antimony sulids, conducting the antimony sultld vapors from the roasting chamber, and oxidizing sa-id'vapors to form antimony oxid.

2. A process of treating' ores containing metal sulfide, comprising heating a thin layer of the ground ore in a closed roasting chamber to a temperature sucient to volatilize the metal sulfid, conducting the metal sulfid vapors from the roasting chamber and oxidizing said vapors toform the metal oxid.

ln testimony whereof l have signed my' name to this specification.

WlLLlAM A. NGHAM.

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