US1467037A

US1467037A - Chloridizing of ores

Info

Publication number: US1467037A
Application number: US350576A
Authority: US
Inventors: Hirt Jules Hector
Original assignee: ALVARADO MINING AND MILLING CO
Current assignee: ALVARADO MINING AND MILLING Co
Priority date: 1920-01-10
Filing date: 1920-01-10
Publication date: 1923-09-04
Anticipated expiration: 1940-09-04

Description

Sept 4L, w23, mama? J. H. HlRT CHLORIDIZING OF ORES Filed Jan. l0, 1920 patented Sept. ei, i923,

sauren. sra-tres JULES HECTOR msm, or NL raso, Tnxas, AssrGNcR To ALVARADO MINING AND MILLING coNtPANY, or 'New Yoan, N. Y., a CORPORATION or MAINE cHVLonrDIzINc or' onus.

Application iledV January 10, 1920. Serial No. 350,576.

To ,all `whom t may concern Be it known that I, JULns HECTOR HINT, a citizen of the United States, residing at El Paso, in the county of El Paso, State of Texas, have invented certain new andA useful Improvements in the Chloridizing of e Orcs; and I do hereby declare the following to be a full, clear, and exact description of the invention, such' as will enable others skilled in th art to `which it appertains to make and use the same. j

A' This invention relates to an improved process of chloridizing ores, concentrates, and other metallurgical products, to convert the metal values into chlorides or Oxy-chlorides which can be subsequently recovered, for

example, by leaching. It is a characteristic advantage of the invention that the ch-loridizing operation is effected without objectionable losses of metal values by volatilization or decomposition of the chlorides or Oxy-chlorides. Y

The' chloridizing of gold, silver, or copper ores is recognized to be adiiticult'and delicate operation because of the'losses which tend to take place, by volatilization or de composition, .if the temperature is too high, the volatilized chlorides v'escaping and being lost or being decomposed into insolublemetal values which resist the subsequent leaching operation. It has accordingly been proposed to carry out the chloridizing of the ores at a temperature below the melting point of sodium chloride, that is, at temperatures below about `800 C., and even at temperatures far below this, inasmuch as certain of the metal chlorides have a much lower melting temperature; and it has been proposed to eiiect the chloridizing of the ore by subjecting themixed ore, usually a sul-- iide ore, and chloride, to oxidizing conditions, such as result from the introduction 1 of air or of products of combustion, so that the sodium chloride or other chloride would be decomposed to form chlorine as the eiiec- `tive chloridizing agent. Such processes are of limited applicability, because yof the low temperatures required to prevent loss by volatilization, and the objectionable high losses that take place if higher temperatures are employed. y

According 'to the present invention, the objections incidentto such prior proposals are largely overcome and the chloridizing operation is eiected without objectionable loss of metal values byvolatilization or def composition. g

I have discovered that if a body or column' of crushed ore is caused to pass through a closed or sealed atmosphere of heated chloride vapors, not only can the volatili'zation losses be substantially eliminate`dbut the temperature can be varied between rather wide limits. I have further discovered that this process can be advantageously carl ried out with non-sulde ores, so that sulfur or suliides are not present 0r required to generate the chloridizing atmosphere from the chlorides.

@ne type of furnace adapted for use in the practice of the invention as4 shown in the accompanying drawing in which Figure 1 is a vertical section of the furnace; Figure 2 is a siniilars'ection inthe plane transverse to the plane in Figure l; Figure 3 is a vertical section through the 'heating iiues; and Figure 4 is a section at the line 4 4, Figure 3.

' The improved process of the present invention can be carried out in different ways,

and in different types ofapparatus, provided the ore body is subjected to the chloridizing -action of the vapors of sodium chloride (or its equivalent). The ore may thus be fed into a reaction chamber containing vaporized sodium chloride, and heated in such chamber to the necessary tempera` ture for the chloridizing reaction. I have found that a particularly advantageous manner of carrying out the improved process is to mix the ore, crushed to a suitable size, with the proper percentage of sodium chloride or other chloride, such as calcium chloride, magnesium chloride, or 'iron chloride, and progressively feed the resulting mixture into an 'uprightpor vertical retort or chamber, and to heat the mixture therein to a suhc'ient temperature and for a sutilcient time, to bring about the desired chloridizing of the metal values. The upright or vertical retort or chamber 5 may advantageously be of recta/ ngular cross-section and of a construction similar to that of cokeovens, but made of materials resistant to the chemical action of the materials undergoing reaction therein, Jfor example, of firebrick. These upright or vertical retorts or chambers may thus be made of rebriclr and with ilues 6 in their side walls, with provision for example, burners 7 for heating the retorts or chambers at their central portions, or for ieee a sufficient portion of their length. It is desirable not to extend the heating fines for i lthe entireheight of the retorts, or, if the Vthelovver part of the retort.

flues at the upper part of the retort or cham.

ber to preheat the incoming mixture.

'When the retort or chamber has been once charged, the process becomes continuous, and requires merelythe charging of further amounts of the mixture of ore and chloride atthe top and the discharging 0f the cooled chloridized ore at the bottom through a chute 10 Wi'hich is provided with a closure l1. The ore itself forms an effective seal for the retort or chamber, inasmuch as the cooler portions of the ore at the inlet end of the chamber effectively condenses any chloride vapors and carries them back into the reaction Zone. The cooled chloridized ore at the lower end of the retort or chamber similarly prevents escape of chloride vapors, although there is relatively little tendency for these vapors to escape With the ore at the bottom, inasmuch as the vaporized chlorides tend rather to rise to the upper parts of the`retorts or chambers. As the mixture of ore and salt reaches the heated reacting zone, the vsodium chloride melts and becomes vaporized so that the reaction zone\ of the retort or chamber contains a more or less saturated atmosphere of the vaporize'd chloride. This insures that all parts of the ore are subjected to the action of the vapor,.

and thorough chloridizing of the metal values as they pass through the hot chloride vapors and are brought into reactive contact therewith.

In a furnace construction of the character above described, thatis, a vertical or upright retort or chamber, or a series of such retorts or chambers, heated by conductionl through fines in the side Walls thereof, the

charge passing through the furnace is subjected to preheating as'it enters the upper parts of the retorts or chambers. andthe preheated charge is then subjected to the reaction zone, the reaction being promoted by the preheating of the charge. After the reaction, the chloridized ore then passes down through the cooling zone where it serves to preheat the air for combustion. The heating of such furnaces can be effected with oil or gas as the fuel in a manner which Will be readily understood. In such. a furnace, as above pointed out, the cold descending ore entering the retorts or chambers forms an effective seal preventing any tendency of the hot chloride vapors to escape through the top of the retorts or chambers. The chlorides are thus kept Within the retorts or chambers untilthey have exerted their desired chloridizing action, andY the products v of this. chloridizing action then escape from the bottom of the furnace. If a considerable excess of sodium chloride is used, this .excess may pass away vith the chlorized ore, but, inasmuch as the tendency is for the hot chloride vapors to rise and not to descend With the hottest ore as it travels through the lZone of highest temperature, objectionable escape of the chloride in' vapor' form iseffectively. pre-vented, proi vvided the chloridized ore is permitted to cool sufficiently before it is discharged 'fromthe furnace. i

' The process of the present invention, as above pointedlout, is of particular value for the treatment of non-sulfide or'oxidized ore, as distinguished from sulfide ores; although it is also applicable to the treatment of sul-- fide ores. Even low grade ores, that is, ores containing but a small percentage of metal values, can be effectively chloridized, and the values converted into chlorides or oXy-' chlorides Well adapted for the subsequent recovery thereof by leaching. Ores containingy as high as 10% of copper have been effectively chloridized in this Way. Ores rela-4' 'tively rich in gold and silver have likewise been eectively chloridized, and the gold and silver subsequently recovered from the chloridized ores.

The amount of the common salt (sodium chloride) or other chloride, such as calcium or magnesium chlorides or iron chloride, Will vary somewhat With variations in the values contained in the ores. to be treated. lVith gold and silver ores, it is of advantage to use only a relatively small amount of common salt or other chloride, for example, one'per cent or less, and ores treated With such amounts of chloride are particularly Well adapted for subsequent leaching by the cyanide process. In general, only a feu7 per cent at most of theY chloride will be required.

Any excess isv unobjectionable if the values are to be subsequently leached with a chloride solvent, inasmuch as the excess chloride Yused will assist in the subsequent leaching operation and will be thereby recovered. The chloride can be mixed with the ore in any suitable manner. vThe intimacy of intermixture can be promoted by using a solution of the chloride, but this will not usually be necessary because the chloride, even if added in a solid form, will be subsequently vaporized and will mainly react in its vapor state, so that'thorough chloridizing will be effected.

Among the characteristic advantages of CII ' sen fine state of subdivision. ,The sodiumv chloride or other ,chloride similarly does not require fine grinding or thorough mixing, but the required intimacy of intermixture and reaction is insured by the fact that-the chloride is vaporized and is present in the reacting Zone,` in part at least, in.

vapor. form. `Furthermore, a minimum amount of the sodium chloride or other chloride is` required, although any excess. not consumed, will pass through unchanged and may berecovered in they subsequent leachingoperation. Even extremely high temperatures may not be objectionable, in-v asmuch asescape of the volatile chlorides is prevented, but such temperatures may even be advantageous in facilitating the reac-A tion and shortening the time required. The temperature regulation thus becomes of less importance, although the temperature should, of course, be suhcient to insure rapid and effective chloridizing. No sulfur or suliides are required in the ore to generate the chloridizing atmosphere; and, if sulfides arepresent, the ore is not subjected to atmospheric oxidation, but Athe reactionis` brought aboutby the vaporization of the sodium chloride or other chloride Which reacts in its vaporized condition with the metal values, although reaction may like-v Wise take place to a reater or less extent directly with the mo ten sodium chloride, to the extent lthat it is present unvaporized vin the reaction zone. InasmuchV as there is no iiow of gases into and out of the reaction zone, there is no loss of volatile chlorides duetto convection therewith.

The ore employed need not be previously dried, but may be used in a moist state, inasmuch as any moisture which it contains Will be readily removed in the upper preheating zonekof the furnace.

Instead of carrying out thef process in furnaces of the construction above referred to, other suitable types of furnaces can be used which will enable the desired heating and reaction to be brought about. Horizontal or inclined heated chambers or retorts can thus be used, provided they are provided With suitable heating means for heating them to the proper temperature and with means for supplying thereto the orel and chlorideand for removing therefrom the chloridized ore. The temperature required for the process can, as above pointed out, be varied rather widely, inasmuch as considerably'increased temperatures Will not cause objectionable loss ofthe volatile chlorides, or objectionablev decomposition thereof.; When common salt (sodium. chloride) is used, Which-has a melting point of about 804, the temperature lshould preferably be maintained around 800 'to 900 or somewhat higher.

With calcium or magnesium chlorides, Which have a somewhatk lower melting point,

somewhat lower temperatures can be used.

The cold chloridized' ore can be subseuently treated in any suitable manner for t e recovery of the values therefrom. lThese values, inthe form of chlorides or oxychlorides, are Well adapted for recovery by leaching operations, forexample, by leachprises subjecting a body of ore fed at a ratev which ensures the presence of a layer' ofy cooler ore overlying the reaction zone, tothe chloridizing action of an atmosphere containing the vapors of a suitable volatileV chloride While protecting the same from atmospheric oxidation and preventing escape of volatilemetal chlorides by condensing the latter in the overlyin layer fof coolerl ore.

A2. The method ofc loridizing ores, metal- I lurgical products and .the likey which comprises mixing the ore with a suitable chloi ride, feeding the mixture at a ratewhich ensures the presence ofa cooler layer overlying the reaction zone, heating the mixture While protected from atmospheric oxidation to a suiiicient temperature to cause reaction between the chloride and the metal ivalues of the ore, and preventing escape of the volatile metal chlorides by condensing the latter 1n the overlying coolerlayer.

I 3. The method of chloridizingores, metali lurgical products 4and the like, vv'vhich com-v prises mixing the ore with a suitable chloride, confining the mixture as a compact column in a suitable receptacle and heating the column intermediate its ends Whilev protected from contact' with the products of combustion to a sufficient temperature to efi fect the desired chloridization.L

4. The method of chloridizing'ores, metallurgical products and the like, which comprisesprogressively feeding a charge of ore admixed with a suitable chloride through a reaction zone at a rate which ensures the presence of a cooler layer overlying the reles action zone, heating the mixture to a sufficiently high temperature to effect the de-1 sii-ed chloridization and preventing escape of,the volatile chdorides from the charge by condensing the latter in the overlying cooler' layer.

5. The method of chloridizing ores, metallurgical products and the like,-which 'com- `prises progreively-feeding a charge of ore admiXed with a suitable chlorideinte a preheating ione and then into ka reacting zone,

heating the same in the reacting -zone to the reactingtemperature while protected from' atmospheric oxidation, yand subsequently passing the chloridized ore through a suitable cooling zone, the preheating and cooling zones being arranged to prevent escape y of volatile chlorides. through the material contained therein. f

6. The methodof chloridizing ores, metallurgical products and the like, which com- -p'rises establishing a body of such-,material admixed With a chloridizing agent and subjecting the body to heat lfrom an external souro'e at a zone intermediate its ends While the `ends are maintained in a cooler state.

ends are maintained in a cooler state'and' advancing the body through said zone bythe Withdrawal of chloridized material at one end and the addition of fresh material at the other.

In testimony whereof I affix my signature.

JULES HECTOR Hier.