USRE15931E - Volatilization of metals - Google Patents

Description

ozone: a. moron, or 21mm, am) summer. I; snnnon, or saw nun.

vonarnrzarrox or 12mm.

lb Drawing. .Original Io. 1,468,016, dated June 5, 1928,, Serial No. $7 9,888, filed August 5, 1928.

Application for reissue fled latch 18, 1824. Serial ll'o. 700,146.

concern: the process of Be it known that ive, Gnoncn H. Wmrorr and 84mm. M. SEDDQN, citizens of -the United States, residin respectively, at 5 Eureka, in the'county o Juab and State of Uta and at Salt Lake City, in the county Lake and State of Utah, have insalt I to flotation manew and useful Improvech ines; here, in turn, a finlshed concentrate and a'tailing were made. The flotation tailing was filtered and partially dried a rotary kiln, where, after the addition of a quantity of an alkaline or alkaline earth chlorid -m excess of the combining quantity necessary to effect chloridizing of the metal content of the feedythe whole charge was subjected to the action of heat and the meta s were volatilized as chlorin compounds, and were recovered as such in the form of fume. In carrying out that method, we discovered that'unde'r certain conditions, hereinafter referred to, the addition of chlorids or any other substances,

or the purposeof chemically reacting with the volatilizable constituents and thereby rta m ments in the Volatilization of Metals; I we do hereby declare the following to be a full, clear, and exact description of the same, such as will enable others skilled in the art to which it appertains to make and use 0 same. I

This invention relates to the extraction of metals in ores, or from other mixtures or they may compounds in which 1 proportion by flotation concentrahave not, heretofore, been capable of satisfacto extraction on a commercial scale by chloride or other volatilization p 1! accordance with the present invention, we add no .chloridizing agent, thus permitting the use of a higher temperature than otherwise 'without fusing t e non volatilizab able materials resent, and this results in a th higher yield 0? the volatilizable metals if other chloridizing agent; from which we' the composition of rnace charge is ave concluded that such minerals, if ocproperly regulated as hereinafter set forth; curring in substantial roportions, should and the non-addition of the chloridizing iminated or reduced in amount before nt results, in obtaini aflue-gas emplo g our invention, .or the charge 'ch, owi to the absence of ee chlorine shouldf by other means, be caused to be of oric acid and other acid com- 'such composition as to act in the manner in the presence of chlorids, hereinafter defined. Ptarmigan. the successful use of bag-filtration e conditions hereinabove referred to are attained in the highest degree by cor- In the Patent No. 1,264,586, of George H. relation of the composition of the furnace igton, one of the present applicants, a feed, the temperature in the furnace, the moss is described In wh' first subjected to treatment by standard cone centration methods, such as gravity concenbtain a higher extraction and a more desirable product if stances are added in the volatilization roce lscoyered also that if the currents within the furnace; whereby the talhng from 5: metals are substantial] comgetely b a rocessknown volatilized at a tem erature low in e practice of which liquefaction 0 any considerable part tration and flotation and that operation is treated as chlond volatilization.

facllitating volatihzatlon, is unnecessary as time of tment and the deiree' of thoroughnes of the exposure of 1; charge to at at no ,such sub- 7 of the charge melt or 7 char liquefaction of of the non-volatilizable constituents of the will take place. Uniformity an uic ess of heating and the degree of t oroughness of exposure of the charge, while not essential considerations, are imrtant factors in improving the recoveries and in increasing furnace capacity.

In the practice of the present invention, the range of temperatures throu h which volatilization of the metals takes p ace is determined as to its lower limit by the tem- Z the volatilizable elements sublime, and as to its limit by the temperature at which any considerable part of the rature at which upper non-volatilizable constituents takes place.

* volatilization of the metals temperature time of treatment to exposure of a furnace g'ases' so method ing tables to remove some metallic compounds,

lead,

-andiron,that.

We so regulate the composition of the furnace charge that substantially complete will occur at a below that at which liquefaction of an nsidera'ble part of these nonvolatilizab e constituents takesplace. It is desirable in mostcases to so regulate the composition of, the charge that incipient fusion of a substantial part of the non-' volatilizable constituents will occur atthe same temperature. We also re late the the degree 0 temperature, the highest tem erature requiring the shortest period'and t e lowest temperature requiring the longest period of heating. We'likewise regulate the thoroughness of the charge to the current of that volatilization of the meta and removal thereof will be substantially complete within thetreatment r10 i A descri tion of a specific example of one practicing this invention 01- lows: Y

An ore was treated-that had the following composition: Gold, 0.065 oz. per ton; silver, 29.3 oz. per ton; lead, 9.4 per cent; silica (SiO, 61.3 per cent; iron, 8.1 per cent; lime (aO), 2.6 per cent; sulfur, 3.9 per cent. This'ore was crushed to pass a -mesh and concentrated on shakof the heavier such as, for instance, ulfids, lead carbonate,

, was reground to (pass a 48-mesh screen an by was then treate froth flotation. -This'treatment remoyed a further part of the sulfids and produced a tailing suitable, for treatment by volat1l1za-' tion. The assa of this material was as follows: Gold, 0. oz. per ton; silver, 14.5 oz. per ton; lead, 44.1 per cent; silica (SiQ,),

iron and zinc etc.- The table tailin 70.1 r cent; mm, 7.4 per cent; lune as): 2.9 per cent; sulfur, 1.7- per cent. 0 concentration above described so the material treated, by 'elimination of low-fusing metallic sulfids and by increase in the gloportion of. silica to lime temperature. of 1'1 w furnace is lessened, furnace ca heating throughout the lengt not for smelting.

tion of the non-volatilizable portion of the material wasraised, with resulting benefit to the subsequent volatilizing operation.

The flotation tailing was next filtered and dried and then introduced into the volatilizing furnace. By re-dryin the feed, fuel consumption in t e' vo ati izing acity is increased,- and incipient fusion 0 the charge near the feed end of the furnace is more readily accomplished.

Volatilization was performed in a rotary kiln eighteen (18) feet long and thirty-six (36) inches external diameter, of one-half inch per foot and linedwith four and one-half (4 inches of firebrick. -The furnace was fired at the feed a flame extending to or nearly to the discharge end of the furnace was maintained, in order to provide substantially uniform h of the furnace. This method of firing efiected incipient fusion of the finer non-volatile particles of the charge very introduction of the ore into the furnace. The finer particles, thus softened, cohered and were thereby prevented from being carried by the furnace gases with the volatilized metals into the flues and fume-collecting apparatus. The grade of the fume is raised" by thus eliminating non-volatile dust. This makes a more satisfactory prod- Another advantage in this 'method of firing'lies in the fact that any furnace accretions th produced near the feed end of the furnace, where they are. readily accessible for removal.

The heat in the furnace w'as maintained at a temperature. such that the calcine or wasteproduct discharged showed incipibnt fusion. In this particular operation this temperature was between $300 and 2500 de s F.

a e kiln was charged continuously at the rate'o'f six tons per twenty-four hours and was revolved at a. speed of one revolution per minute. The time of treatment was about one hour. Under these conditions the degree of exposure of the heated charge to the furnace gases was sufiicient to remove the volatilized metals in the time allowed.

The gaseous product of thefurnace was cooled and filtered through woolen and cotton bags and the fume thus collected.

The nature of this product was such that it was non-corrosive to these'bags.

The products resultin treatment assayed as fo owsz 1 Fume; gold, 0.31 oz. per ton; silver, 181.0 oz. (per ton; lead, 87.3 percent; silica (Si 25.0 per centiron I sulftur, 3.2 percent; lime (CaO), 4.5 per can with a slope shortly after the.

at may form are from the I above V 3.7 per cent;

gold.

. necessari Calcine; gold, 0.01 oz. per ton; silver, 0.5 oz. per ton; lead, 0.1 per cent; silica. (SiO,), 89.2 per cent; iron, 5.0 per cent;

sulfur, 0.1 per cent; lime (CaO), 1.4 per cent.

This tomplete operation represented a recovery of 98.9 er cent of the lead, 98.3 per cent of the silver, 88.5 per cent of the The drawings show a flow sheet which illustrates a practical operation of the process- It is to be understood that a number of variations may be made in the procedure without affecting the principle of the method. For example, there may not be enough coarse valuable mineral in an ore to warrant the use of gravity concentration; or the ore may not require treatment by flotation, if it is sufiiciently free from floatable minerals. An oxidizing roast may precode the volatilizing treatment and may be the only preliminary treatment required. In some cases no preliminary treatment may be necessary, if the ores are roperly selected or mixed. In other cases t e desired composition of the furnace char may be attained by the addition of certain relatively infusible substances, such, for instance, as lime or silica, to the ore. The 'feed may be added either dryor Wet to the volatilizetion furnace. Other types of volatilization furnaces and other fume-collecting devices be used.

he removal of sulfids effected by mncentration or otherwise in the regulation of the furnace charge, as specified, eliminates from the furnace gases, substances such as sulfuric acid and sulfur oxides that are corrosive anddestructive to bags through which the furnace gases filtered. In the chlorid-volatilization process the gaseous product of the furnace is almost y of an acid character and will corrode and destroy cotton and woolen used in its filtration. The collected chlond fumerequires an intermediate treatment to change its chemical composition and make it suitable for smelting. In our process, by reason of the fact that we add no chlorids, the gaseous product of the furnace is not rendered mrrosive and destructive by reason of subdsa-nces added to the charge, and the substantial absence of chlorin in the V collected fume renders this fume amenable to smelting without intermediate chemical treatment.

What we claim is:

1. The process of extracting metals from their ores by subjecting the ore to the action ofheat, which consists in so regulating the composition of the material to be treated that no considerable of its non-volatilizable constituents all. become fused or containing them are state in which they are not recoverable in substantial proportion bystandard gravity or flotation concentrationprocesses, or which occur in ores of'such character that the non-volatilizable constituents undergo substantial fusion or liquefaction at the tem- .perature of volatilization of the metals,

which process consists in so regulating the composition of the material to be treated that no considerable art of'its non-volatilizable constituents sha 1 become fused or liquefied at the temperature at which the metals are substantially completely volatilized. charging such material into a furnace, heating the same to a temperature above that at which the metals will volatilize and not above the temperature at which the nonvolatilizable constituents will exist in a state of incipient fusion, and collecting the volatilized metals. i

3. The process of extracting metals from their ores by subjecting the ore to the ac' tion of heat, which consists in so correlating the composition of the material to be treated. the temperaturmthe time of treatment, and the exposure of the material under treatment to furnace gases, that the metals shall. be substantially completely yolatilized below the temperature at which liquefaction of any considerable part of the non-volatilizable constituents takes place, and collecting the .volatilized metals.

4. The process of extracting metals from their ores bysubjecting the ore to the action of heat, which consists in so correlating the composition of the material to be treated. the temperature. the time of treatment, and the exposure of the material under treatment to furnace gases, that the" metals shall be substantially completely volatilized at a temperature not exceeding that at which the non-volatilizable constituents will exist in a state of incipient fusion, and collecting the volatilized metals.-

5. The process of extracting metals from their ores by subjecting the ore to the action of heat. which consists in so correlatin the composition of-the material to he treats the temperatures. the time of treatment, and the exposure of the material undertreatment to furnace gases, that the metals shallfbe substantially completely volatilized at a temperature below that at which liquefaction of an considerable part of these non-volatili za le constituents takes place, and that incipient fusion of a substantial art of the non-volatilizable constituents wil occur at a temperature below that necessary for substantiall complete volatilization, and collecting e volatilized metals.

6; The procex of extractin metals from oxidized ores by subjecting t e ore to the action .of heat, which consists in so correlating the composition of the material to be treated, the temperature, the time of treatto the action ofheat, which consists in so correlating the composition of the material to be treated, the temperature, the time of treatment, and the exposure of the material under treatment to furnace gases, that the metals shall be substantially completely volatilized below, the temperature at which liquefaction of any considerable part of the non-volatiliza'ble constituents takes place,

. and collecting the volatilized metals.

8. The process of extracting metals from oxidized ores containing one or more of the metals, lead, silver and gold, b subjecting the ore to the action of heat, w ich consists in so correlating the composition of the material to be treated, the temperature, the time of treatment, and the exposure of the material under treatment to furnace gases,

that the metals shall be substantially completely volatilized below the temperature at which liquefaction of any considerable part of the non-volatilizable constituents takes placefind collecting the volatilized metals.

0 process of extracting metals from partiall oxidized ores. containing one or more 0 the metals, lead, silver and gold, by subjecting the ore to the action of heat, which consists in so correlating the composition of the material to be treated, the temp'erature, the time of treatment, and the exposure of the material under treatment to furnace gases, that the metals shall be substantially completely volatilizedbelow the temperature at which liquefaction 'of any considerable part of the non-volatilizable constitutents takes place, and colleding the volatilized meta-15;, J

10. The process of extracting metals from their ores by subjecting the ore to the action of heat,

of heat, which consists in so correlating the composition of the material to treated, the temperature, the time of treatment and the exposure of the material under treatment to furnace gases, that the furnace gases shall be non-corrosive and the metals shall be substantially completely volatilized belowthe tem erature at which liquefaction of any considerable part of the non-volatilizable consti-tutents takes place, and collecting the volatilized metals.

11. The process of extracting metals from their ores by subjecting the ore to the action of heat, which consists in so correlating, the composition of the material to be treated, the temperature, the time of treatment, and the exposure of the material. under treatment of furnace gases, that the metals shall be substantially completel volatilized below thetemperature at whic liquefaction of any considerable part of the non-volatilizable constituents takes place, and collecting the volatilized metals in the form of a fume of substantially nonchlorid character.

12. The process of extracting metals from partially oxidized ores containing one or 'more of the metals, lead, silver and gold, by

subjecting the ore to the action of heat, which consists in so correlating the composition of the material to be treated, the temperature, the time of treatment, and the exposure of the material under treatment to furnace gases, that the furnace gases shall be non-corrosive and the metals shall be substantially completely volatilized below the temperature at which liquefaction of an considerable part of the non-volatilizab ee constituents takes place and collecting the volatilized metals in the form of a fume of substantially non-chlorid character.

13. The process of extracting metals from their ores by subjecting the ore to the action w ich consists in regulating the composition of the furnace charge by removing from the ore a substance or substances that liquify or bring about liquefaction of an considerable portion of the non-volatiliz 1e constituents at a. temperature below that at ,which substantial] complete volatilization of the metals will take GEORGE H. WIGTON. SAMUEL M. SEDDON.

place, substantially as described;