US1904583A - Process of treating iron ores - Google Patents

Description

April 18, 1933. E. w. wEsco'rTv 1,904,583

PROCESS OF TREATING IRON CRES Filed 001'.. 24, 1929 BY we/*4% t7% ATTZl/aYS Patented Apr. 18, 1933 UNITED STATES PATEN'I.V OFFICE ERNEST W. WESCOTT, 0F NIAGARA FALLS, NEW YORK, AMSSIGNOR, BY MESNE .ASSIGN- i MENTS, TO SULPHIDE CORPORATION, A CORPORATION OF DELAWAREv PROCESS OF TREATING IRON ORES Application led October 24, 1929. SeraI No. 402,010.

This invention relates to an improved chlorination process for the recovery of iron oxid and other values, including sulfur when present, from ores of, or containing, iron, and in particular to a modified form of the split cycle process described and claimed in my co-pending application Ser. No. 254,805.y

In my co-pending application above mentioned, I have described an embodiment of the split cycle process in which the several steps of chlorinating a sulfid ore to displace and volatilize the sulfur with formation of ferrous chlorid, further chlorinating the ferrous chlorid to ferrie chlorid, and burning the ferrie chlorid as vapors with air to form ferrie oxid and liberate the chlorin for re-use, are carried on in a continuous manner with voidance from the system with the sulfur of an amount of inert gases (nitrogen, CO2, etc.) equal to that introduced with the air, and producer gas when used, in the ferrie chlorid burning step. This is made possible by 'carrying on the sulfur-displacing step andthe ferrous chlorid-'chlorination step in separate and distinct reaction chambers or zones, and at a suitable point in the iiow of dilute gaseous chlorinating agent dividing the stream and leading the sub-Hows thereof to the respective zones above mentioned, recovery for re-use in the cycle of chlorinfrom its combination with the iron being effected by leading ferrie chlorid vapors from the ferrous chlorid clilorinating zone directly, without condensation to void inert gases mixed therewith, to the ferrie chlorid burning zone. Since at least twice as much chlorin is required in the sulfur-displacing step as in the ferrous chlorid chlorinating step, it follows that the sub-flow led to the sulfur-displacing zone will always carry at least twice as muc-h inert gases as are returned to the oXidizer with the ferrie chlorid vapors coming from the ferrous chlorid chlorination Zone. The inert gases led to the sulfur-displacing zone are voided from the system with the sulfur and hence after a short period of operation a balance will be reached between the amount of inert gases introduced at the oxidizer and the amount voided with vthe sulfur. t

According to the specic form of the split cycle disclosed in my co-pending application above mentioned, the stream lof dilute chlorin coming from the oxidizer is divided into a major sub-flow and a minor sub-flow, proportioned according to lthechlorin requirements respectivelyy of the sulfur-displacing step and the ferrous chlorid chlorinating step. The majorv sub-flow is utilized either directly in the sulfur-displacing step or first passed over sulfur, thereby forming sulfur chlorid which is used in such step. The minor sub-flowis led directly to the ferrous chlorid chlorination zone where the chlorin contained therein is reacted under proper temperature conditions upon the ferrousl chlorid converting same into ferrie chlorid vapors, which together with the residual inert gases introduced with the chlorin are led to the oxidizer. and burned.

Owing to the dilute condition of the chlorinating agent the volatilization of the displaced sulfur takes place at a temperature considerably below the vnormal boiling point of sulfur. With the dilution-obtainedy by the use of air in the ferrie chlorid burning step, volatilization can be lmaintained at temperatures around 300 C. and ordinarily when the operation is conducted with su1' fur vapors leaving the system between 320 and 350 C. and the amount of chlorinating agent used .in the sulfur-displacing lstepI is merely enough to effect the displacement of the sulfur and the formation of ferrous chlorid such vapors will be free from ferrous and ferrie chlorids and may be easily condensed and recovered in 'a pure state.

According to the present invention, the advantages of the split cycle are obtained by splitting the flow of gaseous chlorinating agent at a different point in the cyclethan proposed in the prior application.` To be specific, instead of burning all of the ferrie As in the prior application, when treating sulfid ores the temperatures maintained in the sulfur-displacing zone are so controlled as to insure volatilization of the sulfur freed lfrom its combination with iron. The sulfur vapors mixed with the inert gases introduced with the ferrie chlorid vapors are led olf and condensed or otherwise utilized.

The remainder of the ferrie chlorid is led directly as vapors to the oxidizer and burned with air producing ferrie oxid and liberating chlorin for re-use. Y

The ferrous'chlorid formed in the sulfurdisplacing step, together withthe gangue and any non-ferrous metal chlorids and values present in the ore, is led to the second reaction chamber or zone (the ferrous chlorid chlorinating zone) where it is contacted with the chlorin recovered from the minor sub-How as above described, under such temperature conditionsthat the ferrie chlorid formed is volatilizedl and removedf It is then split into two streams, and the split cycle is repeated.

In order better to illustrate my invention, I have shown in the accompanying drawing aflow sheet depicting the course of travel of the materials. i At -10 I have shown. a chamber in which the first stage of chlorination-that is to say, contacting of the raw ore with ferric chlorid-is carried on. Ground dry ore or concentrate, or any4 raw sulid material of choice, is fed into the chamber as indicated by the arrow. A stream of dilute ferrie chlorid vapors is fed in through pipe A12, from a source to be later described. The orethus flows in countercurrent to the stream of chlorinating agent. The ferricchlorid very soon becomes fixed as ferrous chlorid, according to the equationabove. As in the process described inv my co-pending application above mentioned, ltemperatureconditions in the'chamber 10 are ordis narily so'controlled that a temperature is maintained sufficient to effect volatilization of the liberated sulfur but insuf'icient to effect anydsubstantial volatilization of the ferrous chlorid formed. However, the use ofv temperatures suiiicient to effect partial vaporization of the ferrous chlorid is not preeluded and for some purposes and when'the process is being conducted without requiring extreme purity of the sulfur directly produced, this may be permissible. f

The mixture of inert gases and sulfur vapors may be withdrawnfrom the chamber l() through a pipe 14 and then led through a dust chamber 16 into a sulfur condenser 18. This condenser may consist of the general type of a tubular boiler such as described and claimed in my co-pending application Serial No. 368,568, in which the sulfur vapors are contacted with water-.cooled surfaces maintained at a temperature corresponding to a steam pressure of fromr2to just below l6 atmospheres (absolute pressure) The sulfur condensing within this temperature range is not hot enough to be viscid and runs freely. As indicated in the drawing the pure liquid sulfur iswithdrawn at 20, the waste gases at 22 and low pressure steam at 24.

The vferric chlorid introduced at`12'is,`as has been explained, just suflicient to convert all of the iron of the ore to the ferrous form, so that as the material reaches the discharge end of the chamber 10 it will consist of ferrous chlorid, mixed with chlorids of such other metal values as may -be present in the ore, and the gangue constituents if any. This material, in the solid state,.is transferred preferablywhile hot toV chamber 26, through conduit 28. This chamber represents the second stage of chlorination, wherein ythe solid ferrous chlorid is converted into the volatile ferric salt.y At 30, an incoming stream of chlorin diluted with inert gases,'meets the descending stream of partially chlorinated material. Ferric chlorid is formed, which, being volatile at the temperature of operation, passes out with the inert gases through conduit 32. This conduit 32 splits into two conduits, one, 12, which passes to chamber 10, where it supplies ferrie chlorid as the chlorinating'agent for the raw ore, and a second conduit 34. yThe relationship between these conduits is such that 12 carries sub# stantially two-thirds of the output of conduit 32', while 34 carries the remaining onethird. Conduit 34 leads to a dust chamber'y 36, and from thence the vapors are led by way of a conduit to an oxidizer or combustion chamber 38.

In the oXidiZer, the ferrie chlorid, still in vapor form, is burned with preheated air, introduced through 40. Hydrogen-free producer gas may be added, as at 42, if desired, to furnishl additional heatv and produce a coarse massive product. In this event, the quantity of air is regulated to secure combustion of the producer gas.` Solid ferri'c oxid is formed and is-.discharged and'collected at 44. The chlorin, mixed with residual aircomponents and producer gas combustion products, leaves theoxidizer at 46, passes through a dust chamber 48, andV is introduced at 30 into chamber 26,` tocomplete the second stage of the process. Vhile in theory, the chlorin travels in a completely closed cycle, without loss, in practice, metals other than iron will lcause a gradual removal of the chlorinfas chloride, being discharged from the system at 50. In order to compensate for this loss, additional or make-up chlorinl may be introduced as needed at 52, or at any other suitable point. If introduced at l2, the makeuplchlorin may be in the form of sulfur chloric f Kiln 1() may be of any construction insuring intimacy of Contact between the gaseous chlorinating agent and the raw ore; details thereof are unimportant, eXcept that it shall be long enough to permit all of the ferrie chlorid introduced to be reduced to the ferrous state before reaching the sulfur vapor outlet. 'Ihe second kiln 26, is sufficiently large, compared with kiln l0, so that all the ferrous chlorid furnished it can be converted to ferrie chlorid and no unconverted ferrous chlorid can pass out with the gangue.

As mentioned more generally above, both in the process described in my prior co-pending application Ser. No. 254,805 and the present application the stream of chlorinating gases is split in the course of the cycle into a major and a minor sub-flow. In the former, the division is effected after all of the ferrie chlorid has been passed to the oXidiZer and involves the splitting of a stream of dilute chlorin, while in the latter the stream of ferric chlorid is split, and this at a point in the cycle before lthe ferric chlorid burning stage is reached. In both instances the major and minor sub-flows bear the same relation to each other; that is, the major sub-flow constitutes two-thirds and the minor sub-flow one-third of the dilute chlorin or ferrie chlorid vapors, as the case may be, when no non-ferrous chlorinatable values are present and with a still greater predominance of the major sub-flow if such values are present.

While I have more specifically described the treatment of sulfid ores, the invention as hereinbefore more generally indicated, also applies to the treatment of oXid ores. In treating oXid ores, sufficient reducing material, such as carbon substantially free from hydrogen, is added to insure reduction of the iron to the metallic state so that when it is contacted with the hot ferric chlorid vapors coming forward from the later ferrie chlorid chlorinating step, chlorination of the reduced iron to the ferrous chlorid state will proceed smoothly. The reactions that take place may be written thus:

In some cases it may be convenient to reduce the iron oXid of the ore more or less completely previously to the chlorinating step.

The ferrous chlorid produced in the first chlorinating step above described is led to the ferrous chlorid chlorinating Zone, and further chlorinated to ferrie chlorid vapors which are in part burned and in part recycled as in the treatment of sulfid ores.

Under the term sulfid ore I mean to iner thanl limiting, might be shown; and such changes are 'to be considered as included in my invention, which is limited only by the prior art and the scope of the appended claims.

I claim: Y

l. A cyclic process for treating materials containing iron for-the recovery therefrom of contained valuesv which comprises treating such a material in a first step with dilute ferrie chlorid vapors to `convert the iron to ferrous chlorid, the temperature in saidfirst step being maintained above that temperature at which ferrie chlorid willcondense from the dilute vapor mixture brought to said step and at the same time sufiicient to insure volatilization of any sulfur freed in said first step; voiding the inert -gas accompanying the ferrie chlorid used in this first step of conversion from the cycle; then treating the ferrous chlorid in a second step of conversion with dilute chlorin to form ferrie chlorid vapors, and burning part of the ferrie chlorid vapors so formed with air to convert the iron to ferric oXid and to form dilute chlorin for use in such second step while directing the remainder of said vapors to the rst step of conversion.

Q. A process of treating in the dry way and at' elevated temperatures materials containing iron in association with gangue for the recovery therefrom of substantially pure iron oXid and other values, wherein such material is treated in a. first step with dilute ferric' chlorid vapors to convert the iron to ferrous chlorid, the temperature lin said first step being maintained above that temperature at which ferrie chlorid will condense from the dilute .vapor mixture brought to` said step and at the lsame time sufficient to insure volatilization of any sulfur freed in said first step, and wherein `the ferrous chlorid in a second step is further chlorinated to ferrie chlorid vapors by the action of dilute chlorin, the chlorid vapors so formed being separated from the gangue' and any non-,ferrous chloride formed and split into a major fraction which is led to the'first chlorinating step above mentioned and the minor fraction is burned with air to ferrie oXid, which is separated, and to dilutel chlorin containing inert gases, which is returned and used in the second or ferrous chlorid chlorinating step.

3. A cyclic chlorination process for treating materials containing iron in combination with sulfur which comprises treating such a material in a first step with dilute ferrie chlorid vapors to displace sulfur and convert the iron to ferrous chlorid, the temperature insaid first step being maintained above that at lwhich ferrie chlorid will condense from the dilute vapor mixture brought to said step and at the same time above that temperature at which therdisplaced sulfur Will exist formed With air to convert the iron content thereof to ferric oxid and to form dilute chlorin for use in such second step while directing the remainder ofv said vapors to the first step of conversion.

4. A process of treating in the dry Way and at elevated temperatures materials containing iron in combination with sulfur for the recovery of sulfur and substantially pure iron oxid, wherein such material is treated in one step with dilute ferrie chlorid vapors in such amount and at such an elevated temperature that sulfur is displaced as such with formation of ferrous chlorid and the sulfur is volatilized as displaced and is removed as vapors in admixture with the inert diluent introduced with said chlorid vapors, and wherein the ferrous chlorid is further chlorinated in another step to ferri-c chlorid vapors by the action of dilute chlorin, the chlorid vapors so formed being split into a major fraction Which is led to the sulfurdisplacing step above mentioned and the minor fraction is burned with air to ferrie oxid, which is separated, and to dilute chlorin containing inert gases, which is returned and used in the ferrous chlorid chlorinating step.

5. A cyclic chlorination process for treating materials containing iron in combination with sulfur Which comprises treating such a material in a first step With dilute ferric chlorid vapors to displace sulfur and convert the iron to ferrous chlorid, the temperature in said first step being maintained above that at Which ferrie chlorid will condense from the dilute vapor mixture brought to said step and at the same time above that temperature at which the displaced sulfur will exist other than as vapors in the presence of the inert diluent introduced wit-h the ferrie chlorid vapors used in said first step; voiding the sulfur as vapors in admixture With the inert gas accompanying the ferric chlorid used in the saidl conversion step at temperatures at which ferrous chlorid has no appreciable vapor pressure; then further chlorinating the ferrous chlorid to ferrie chlorid vapors by the action of dilute chlorin, and burning part of the ferrie chlorid vapors so formed with air to convert the iron content thereof to ferrie oxid and to form dilute chlorin for use in such second step While directing the remainder of said vapors to the first step of conversion.

6. A cyclic chlorination process for treating material containing iron and non-ferrous metal values in combination with sulfur which comprises treating such a material in a first step with dilute ferrie chlorid vapors to. displace sulfur and convert the ironv to ferrous -chlorid and other chlorinatable metals present to chlorid form, the temperature in said first step being maintained above that at which ferrie chlorid will condense from the dilute yvapor mixture brought to .sa-id step and at the same time above that temperature at which the displaced sulfur will exist other than as vapors in the presence of the inert diluent introduced with the ferrie chlorid vapors used in said first step; voiding the sulfur as vapors in admixture with the inert gas accompanying the ferric chlorid used in the said conversion step at temperatures at which ferrous chlorid and `the nonferrous chlorids present haveno appreciable vapor pressures; then treating theferrous chlorid ina second step of conversion with dilute chlorin to form ferric chlorid, volatilizing off the ferrie chlorid, leaving the gangue and the aforesaid non-ferrous chlorids substantially free from iron chlorids and iron oxid, and burning part of the ferrie chlorid vapors so formed with air to convert the iron content thereof to ferrie oxid and to form dilute chlorin for use in such second step While directing the remainder of said vapors to the first step of conversion.v

In testimony whereof, I have signed my name to this specification this 22nd day of October, 1929. 1

ERNEST V. WESCGTT.

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