US1857494A - Method and means for treating sulphide ores and the production of sulphuric acid thereby - Google Patents

Description

`May 10, 1932', G. Q CARSON METHOD AND MEANS FOR TREATING SULPHIDE oREs AND THE PRODUCTION OF SULPHURIC ACID THEREBY Filed Oct. 6h1925 2 Sheets-Sheet l' Geom: mMPBHL CA nso/V y Mea,

May 10, 1932. Q Q CARSON 1,857,494

METHOD AND MEANS FOR TREATING SULPHIDE ORES AND y THE PRODUCTION 0F SULPHURIC ACID THEREBY Filed 001'..` 6, 1925 2 Sheets-Sheet 2 2 o Imummz GEORGE cA/wpm :Amo/v Patented May 10, 1932 GEORGE CAMPBELL' CARSON', orlLos ANGELES, oALIFoRNrA n METHOD AND MEANS non TRnATiNG SULPHIDE RES'AND PRODUCTION jorY sULPHURro ACID THEREBY Application filed October `6, 1925. Serial No. 60,840.

Generally stated, my invention .relates to a method of and apparatus for treating mixed sulphide ores for theultimate recoveryof the metal values therein and the production of sulphuric acid, the ores, in iinely pulverized condition, being caused to pass in one .direc-l tion in a streamo acid solvent which is `lowr ing in the opposite direction wherebypsull phid-es of the metals are converted into the corresponding sulphates which become dis'- solved in the stream andpass with 1t 1n one direction while the unconverted sulphides and the insolubles pass in the up-stream direction, i

finally leaving the stream at or near .its source. Since metal sulphides varyiny respect of the ease with which they yield tothe acid att-ack, some are sulphated, and the sulphates dissolved, almost as soon` as .theyconf tact with the acid solvent, while others are `highly resistant and are, consequently, carried 'far up-stream before they yield to the acid attack if they yield at all. phates inthe stream thus* tendto separate. from one another; and their substantially Acomplete separation is made possible in practice by reason of the fact that a sulphate in solution is reduced to its sulphide form by:j

y1n quantlty until, at or 'near the end ofthe coming into contact with a sulphide which is more easily sulphatechbeing thus precipitated as a solid which is again advanced up the stream into the region where it was first sulphated, and where it is again sulphated aud the sulphate dissolved. By these alternating reactions and precipitations, whichV may take place again and again, the sulphates `in the stream become so effectual-ly sepeither while in the stream or after withdrawsels through which'lthesolvent is flowing,j

preferably by gravity. The sulphides enter The -sulv being symbolic of an insoluble metal.)

the streamator near one end of the train while thel acid'enters, or is formed, at or' near the opposite end thereof. andV flows*l through YAthe train and outa-tor near the point where the sulphides enter. As will be seen,

the products of the method give to the stream its solvent power, the principal one of which is the anhydride SOgwhich, when introduced into the stream atany desired point, replenish. 'or maintain the strength ofthe acid.

`Near ythe source of thestreamfthe acid is maintained relatively strong in order effectually to'attack sulphides which lhave resistedthe attack ofi-the weaker acidarther downV stream. The acid grows weaker as itexl pends itself in its attacks, except as it is lre?" i plenishedas above stated, until it issubstan`V tiallyzexhausted' lat or nea-r the exit of the; solvent stream. As ity passes along through the train of vessels, it meetsy successivelysul- Ehi des in the reversey order of theirlsusce'ptiility to attack, those more susceptible 'havl ing. already been oxidized and theirsulphates entered into thef solution. While, therefore,-

the solvent-gradually weakens in its acidk contentas it' passes down the'stream, the dissolved sulphates therein gradually increase train, the liquid is saturated therewith. i In Vfact, since the reactions are'generally exothermic, the temperature at that point issuch that the solution may be said to be* supersat tion at the reduced temperature. These sul` rated that they may be individually treated, I phates are treated kfor the recovery of their metal values or are reduced to sulphides and i discharged as such. as products, while the insolubles, suchj; asrPbSOi, AgZSOi, M Y and SiOg, are discharged at the other end of the train for separation in-a known manner.

In carrying'out the process, Vvarious steps may ybe resorted toatfdiierent stages, del '9F' pendent Vupon the local orecontent orthe pre'- dominance of a specific metal or'metal coinpound, so asy to adapt the process to theV treat- Y ment of complexsulphide ores of all kinds; and various treatments-are given some ofthei finally separated metallic salts either for returning part of their constituents to the train tov carry on the process or asa further product of the process.' i

My process may be carried out through a batch system of treatment wherein the progressive reactions take place in separate tanks tofwhicli the reaction solutions and precipitates are progressively transferred in the required directions'v or,"better, in a system which is continuous in so far as they general treat tion in 2 of the drawings, and .of which mentis concerned, beingcontributed to, when expedient, by individual treatment of some of the derivatives. Y ,e In carrying out my method along the lines last suggested, I- prefer to arrange the va-V 2 v rious reactionvessels to provide a lflow, as

revealed in the flow sheet'shown in Fig. 1 ofY theqdrawings hereto, andin whichthe reaction.; vesselsV inthe lmain. train take the Vpreferredorm which iskshown invertical seclatterigure, Figs. 3 and lare details.

In the flow sheet, the general travel of the liquid orsolvent is in the direction of the arrow A. Starting from vessel 98,it passes through Athe successively lower-numbered vessels of themain train tothe one marked 50, Vand thence through the specialetreatment vessels 89 to. 46. Thezyflowv of theoremaf- Y Vteria'l undertreatment is'in the op osite direction, as indicated by the arrow.

Vbeginning with a charge of material to vessel 50. Alarge; part of this material is oxidized and 'dissolved while passing through the train of ormof construction of .vesselsV to 98,'two -adj acent lvessels are shown. whiclrare properly supported on a founda- These vessels,

tion 1, 'comprise a vitreousy or-acid-proof inner shell 2, made in sections, as indicated,

cemented 'together withv an acid-proof ce-A Vmentjand covered bylsuitable lids 3. vFlach vessel is providedV with; an overflow discharging tothe lower part of 4the next vvessel through a suitable tilext, thel upper part of the'overflow widening and terminating ina weir 5 whichv preferably extends across the vessel. The ,successive weirs are gradually I s lower, and lower as the train of'rvessels proceeds in thedirection ofarrow A. A- liquid 6 `introduced into one vessel will, therefore,

i ilow; successively through Vall of the-vessels having lower numbers fromthe top of one tol the bottom ofthe next. The lower portion 2 ,is made conical, asshown, so as to concenlateral passages 10.

trate toward the center any pulverulent material introduced into the vessel for reaction with the liquid. f f

The conical lower portion 2 is preferably i formed of two sections, each of a single vitreous member and with the upper one, as shown in plan in Fig. 3 and in vertical section in Fig. v4, comprising an outer ring with ribs supporting a central sleeve 7 which, when ass'embled in the vessel, in turn supports ver-\75 tical sleeve sections 8` and 9, the latter being open at the upper end and having, in addition,

i rv.Below the lower end of the conical section 2 isa removable bottom section 11, which is seated against aY gasket 12 and is held in place by jack screws 13.,- This removable bote tom, which providesfor cleaning and repairing, houses a duct 14,?througli which the solids from one vessel are led for upward dischargeA to the next adjacent vessel ythrough a pipe 15, the material being forced upward by a pressure jet .arranged under the pipe. Y Y

The upper end of the pipel passes through the wall of the next vessel and teriiiinatesin a bell or hood 25, which is inverted over the open end of sleeve 9 so as to discharge solid'v material from the pipe into the sleeve, while, Y

positioned under the lower sleevesection, is a pressure elevatingrjet 26 which agitates and forces the-solid matter 114e and liquid 6 upwardly to meet the Ydowncoming stream of material from the hood 25. lThis'results in a lateral ejection of the thoroughly mixed matcrial and liquid throughthe sleeve passages 10, the circulation being as indicated by the arrows in Fig. 42.

.A In carrying out my process, the jets 16 and Y 26 are operated by sulphuric anhydride, air or a combinationsof both the anhydride and air, sulphuric acid,solutionerricsulpliatepi' any other suitable agency, and they ensuing reaction usually maintains the temperature of the vessels contents at ornear the Vboiling point. lVhere, however, due to the nature of the material under treatment or to weakness of the acid, the temperature of the'contents falls too low,l steam is also introduced through the jets; and, in some of the vessels, additional steam coils may be used, as shown at 27 in Fig. 2. These coils may open at the 'l Alower end tothe vessel, as indicated at 27.

or they may be closed at that end, all depend-y ing on whether the addition. of more water to the contents is desirable. l

.j The air which may be driven uptlirough the jets 16 and 26 is not merely anfagitating and propelling mediunn'since it aids in the yoxidation kand sulphatizationfof the sul- -phides 'ItV readily attacks the sulphides pyrrhotite and -marcasite and` converts Athe ferrous sulphateproduced therefrom into verricsulphate.. This ferric sulphate is one ofthe most powerful chemical agents known and when formed as just stated, or when it is thereon.

formedand introduced into the streannas hereinafter described, it oxidizes any hydrogenisulphide resent andwith Which it contacts into su phuric acid, being changed thereby back to ferrous sulphate. hydrogen sulphide interferes with the reactions by precipitating sulphides from sulphates already formed and, being noxious, its

escape into the air is objectionable, it )vill'be' that` the air injected through thepjets l vessel'through its `feed chute, or otherwise,

performs animportantfunction;

Having thus given a general description of the main apparatus units, my process Vin the treatment of complex sulphide ores Will now be set forth.

The mixed or complex sulphide ores, un- Y roastedand otherwise untreated except bvy crushing until they are in a tine state of division, preferably such as flotation concentrates, are supplied from a source 28, first, in moderate quantity, to the vessel 50 at the lower end of the train. In some circumstances it may be desirable to introduce the ores at other points as Well, and Fig. 1 indicates that they maybe introduced at vessels 52, w58, G1, 63 and .72. sels are designated for illustration only, as the ores may enter the train at any point Where their presence is required or may be advantageous, as will be more particularly explained hereinafter. The reaction liquid is introduced at or near the upper vend of the train, from which it flows through the vessels of loiver numbers in series toward the vessel 50. The liquid is caused to fill the vessels and overow the Weirs 5, While the ores are introduced at the tops of the vessels, as by dropping them through gate-controlled chutes, all as indicated in 2. The ores fall upon the surface of the liquid and settle downwardly, being violently agit-ated in the vessels by the jets 26 and transferred in an rip-stream direction by the jets 16. The finer particles of some of the sulphides yield almost immediately to the acid attack, and

the resulting' effervescence assists in agitatng the contents of the vessels.

But before a proper appreciation of the reactions can be obtained, it is necessary to consider all of the vessels in the train proper, as

Well as the auxiliary apparatus, as Working to their maximum chemical efficiency, since the Vrelative changes in tlie traveling` solidsY and the oppositely traveling liquids depend Therefore, the various i reaction vessels 50 to 94 must be considered as containing, in their ascending numerical order, sulphide ores of increasing resistance to the acid attack, While the vessels 95 to 98Y contain insoluble matter only. The chemical solvent, the principal reaction agent of which is sulphuric acid, must be considered as being` Weakest in dissolved minerals (inthe form of sulphates) at the vessel 94, as flowing. in the direction of the arrow A, and as .progres- Since the.,

Of course, these particular vessively increasing in its sulphate content to the point of saturation ofsupersaturation vat the vessel 50, tlie sulpliidesbeing passed in the" and, Without operating the jets16, the solvent run slowly through the successive vessels, with agitation by the jets 26, until the proper con.- ditioiis are obtained.

of increasing solutes toward the vessel 50;y that the sulphide in the train are of progres- Vsively increasing resistance to oxidation from the vessels 50 to 94; thatithe liquid is maintained at substantially the boilingtemperature, and. that the materials charged into the vessels consist principally .of a mixture of the sulphides of lead, copper, iron and Zinc, together With their usually associated sul,- phides, such as minor quantities ofthe sulphides of cadmium, arsenic, antimony, bise muth, etc., as Well as a certain amount of the precious metals, silica and other insolublema-` terial, the operation and some of the principal reactions Will now be set forth.

rlhe material is charged intothe train at i Assuming that the liquid is in the condition vessel 50 and, if desired, at other points as well, While the stream of liquid is started by the introduction ofwash Water into the ves'- sels 98to 95 and of acid oracid-forming coinv and by effervescence dueto the reactions, as

stated. The insoluble compounds pass suc cessively through the vessels to 98 Where they are Washed, the Wash Water, and any acid that it has removed from the insolubles, passing to vessel 94 and on through thetrain. After being thus Washed, the insolubles are filtered at 36 and deposited at 37 as a product, consisting usually ofa mixture of insoluble sulphates, etc., as design ated on' the Aflow sheet.

The reacting agent introduced at 94 and elsevvhere, as through the jets 16 andl 26, may y be simply the sul-phuric anhydride (S03), obtained as'hereinafter described, or ferrie" sulphate and air mayalso be used. On meet-` ing the Wash Water from the vessels 98 to l95, the S03 is convertedinto H2SO4. O-r the reacting agent may 'be bothr S03. andi HQSOJLO, thelHgSOlHzO being also Aa-" `product of the method, asis also to'bejde i scribed. Y

Wherever acidis introducedand reaction:A takes place', heat is evolved;i and,.if it werel-k allp introduced at one point the i temperature there would rise. excessively. Therefore, the acid is added at such points and Vin such f amounts as will maintain the requisite 6 strength and temperature of the solvent.

Preferably, the strength of the acid is gradually increased. in the vessels 98, 92, etc., thus bringing the solution to the required strength any point. The solution sliouldhave a temperature approximating the bcilingpoint and a'strength suiiicient for attackingthe most resistant sulphides which it is intended shall yield to it.

vesselin the direction of the vessel 50, it meets a stream of sulphide material traveling through it in the opposite direction, the material in the vessels of lower numbers con- ,attack While the sulphides in the higher numbered vessels are much more resistant to such attack, the acid therein is stronger and someof the sulphides are sulphated and the sulphates are dissolved. YThese sulphates flow down the stream kand presently meet some sulphidev coming in the opposite direction which is more easily sulphated than was the sulphide from which the dissolved sulphatev was formed. For example, copper sulphate higher number travels with and as part of the stream until it meetszinc sulphide. AtV

ence, the copper sulphate is convertedto the phating and precipitating reactions may be represented bythe following typical equa-v tions (2) F'e2(SO4)3+H2S=2FeSO4+H2SO4+S. `When, as in Equation (l), the CuS Yis formed andis precipitated, it joins the other mundissolvedmaterials and is moved back up- 45 stream into the saine vessel, or into one ad- Vjacent thereto, whereV theCuSOL1 was iirst formed.

and sulphatedand the sulphate is dissolved. `Again this sulphate flowsY down-stream until some ,other sulphide is met which changes it Yback to CnS.v This CnS Vis sent back upstream, asnbefo're. Thus, the copper sulphide in the ore` charged into the vessel 50 or else- ,where, is moved Lip-stream by reason of the l jets 16, until it reachesthe Yvessel or vessels in Whichconditions are favorable for sulphating it. Say, for purposes vof explanation, these Y conditions arefcund in a group ofvesselsbear-Y 1 ing the numbers 80 to 86 inclusive. Through- Y d vouttheir travel from vessel 5() to this group, the CuS in the ore hasbeen agitated withthe acid solvent but'has remained a sulphide, because the acid has had other more susceptible Y sulphides toattack or because theacid has G5 been too weak to attack it.V By the time it has Without unduly raising the temperature at As the acid solution Hows from vessel tov taining the sulphidesinost susceptible to acid I sulphide andl is precipitated. These desul-V There the Cr-.S is again attackeded from Fig. l. the acid in this group is strengthened, if lneed be,-by the introduction of H2SO4, as at vessel 82, oreof S03, as-atV vessel83. These particular vessels are designated for illustration only, as the acid may' be replenished at any point, as by introducing the strengthening agent or agents through the jets 16 or 26, as'hereinbefore stated. Irrespective of the precipitations of the sulphides, as referred to above, and due to their differences in susceptibility to attack, the various sulphides in the stream tend toV separate from Vone another, as is obvious. But the said precipitations and reprecipitations greatly assist in this separation, since' they tale place inthe vessels which are farther down-stream than the groups in which the respective sulphates were formed and in which it is desired they be retained, and the precipitated sulphides are automatically returned to their respective groups where they are again sulphated and dissolved. VThus the various sulphates are accumulated in their respective groups so that they may be individually treated. ln the flow sheet it is assumed that the CuSO.,r is in its mostl concentrated form iu the vessel 83 where it may be electrolyzed out in the vessels themselvesror may be passed direct to electrolytic cells, as at 99, for the production of electrolytic copper, the spent electrolyte being returned to the train, as at vessel 73. This direct method of recoveryof the metal values is preferably used where thecopperlcontent'in the ore is relatively small.' YIf the copper content is large, I prefer to'by-pass a Vportion of the solvent sufficient to care for theV accumulating copper sulphate, through atrainl of agitators where itis treated with; FeS to precipitate tlie'copper in sulphide form and to produce ferrous sulphate as a preliminary step in the production of ferrie sulphate for use in the n main reaction'train. This latter feature will along, growing richer and richer in sulphates' and weaker and weaker in its power of attack.V At the'vessel 50 it receives aquantity of fresh sulphide material, and any power which it may-have retained is expended thereon, so that the solvent is substantially neutral when it finally lea-ves the train at said vessel. Owing to the weakness of the acidv at and near the lower end ofthe stream, such relrCtions as take place generate .but a rela- Y Vtively'small amount of heat. Consequently,

it Vis desirable'lto supply such heatas may be necessary'to further the reactions and to pre-V sol vent :precipitation of the snlphates through crystallization. This is accomplished bythe use of the steam coils 27, or bythe injection of steam from the coils ttt-"27' or through the jets 16 or 26.

, While the solvent `has been Lgrowing richer and richer in dissolvedsulphates, many of the sulphides have disappeared `as such and the remaining solidmaterials inthe train are, in the 11p-stream. direction, progressively more and more resistant to the acid attack, thosel passing beyond -vessel 94 being insoluble.

In Fig. l the train of reaction vessels is shown as extending from 50 to 94, Whichis suiiiciently long for 'purposes ofv illustration and for many practical operations. The

length of the train used would depend upon the materials employed and uponthefdesi-red completeness of separationof the sul-phates in the stream. Obviously, the longer the train the more completely'Wi-ll this separation be effected. l A i' 1 The attack of the acidon lmost 4ofthe metallic sulphides present rin the ore results in the formation Aof I-IS. Thus, i Y (3) ZnS+H2SO4=ZnSO4+H2SV- Although it is a gas.,- 4the HQS is absorbed by the solution; and, rif it were not removed or converted into other compounds, it would interfere rwith the sulphatin-g process. 1 In fact. the solution would become so far saturated with it that the metal sulphates would be desulphated substantially :as fast as they could be form-ed. This is shown by Equation (2) or by the following: l .r

' -y (i)oasongsecasa-nso..

It is, therefore, important that the HgSbe converted into somethingwhich Will notreduce the sulphates in the solution. lBetter still if it can be converted 4into H-QSOi` and made to strengthen the solvent; Further, there are some conditions in which H25 is formed and in which it so disposesitself as greatly to krete-.rd the sulphating process'. For example, certain sulphides of coppercontain'arsenic or antimony, and it is diiicultto convert them into sulphate form for the reason that the HZS evolved adheres to the particles and surrounds themas an envelope'or film and thus insulates them from the acid. Any agent introduced into the solutionjwhich will attack and remove this envelope will gre atlyfacilitate the attack on these Vsulphides and prevent them from passing out vviththe insolubles beyond the vessel 94:. The removal of theHgS, as such, yand its conversionI into a benelicial reagent is,r therefore, an important feature of my inventionwhich Will noivibe explained. ,y The sulphidcs of iron in the train are readif ly attacked by the acid ,the reaction being of the natureshown in Equation (3). But iron ldisulphi.c'le,r FeSE, known 'as primary kpyrite, yields ivery slowly to the H2804 .and f have discovered that this pyrite floats -as-a scum'on the surface ofy the vliquid and gives 'olf the be removed by skimmingwhereverit maybe notedV However, it Wil-t not appear in zany considerable quantities kuntil the pynite reachesthe relatively strong acid, say vat vessels 87- and 88.?v iAt that point, asgsh'owvn in noXiousESOlb This objectionable pyritemay "70 iny the treatment of certain ofthe sulphates y which have passed beyond the main train at the vessel 50 and also in the preparation of ferrie sulphate for use in the train/to attack theobjectionable HZ'S therein.'

' As'fstated, if the` copper in the ore is plentiful, .I prefer to shunt out aportion'of the solvent, I`the amount so shunted being substantially equal Vtov `the coppersul-phate which shunt of copper-sulphate bearing solution is Ato separate the copper. from the other sul` phates and'to produce a supply of ferrie sulf phate from' thefFeS produced asjabove described.L Such ashunt is shownconnecting the vessels 7 5 and 76. These vesselsdiffer .fromthose of the main train, since they are adapted `merely for agitating thematerials andfor sending both the liquid andthe solids in the same y direction through the veseslsv 29 shunt Vtrain of. agitators ispreferably limited in quantity vso as to 'assure that/it will act on the CuSO4 only. For example; -if the quantity of CuSO4 entering the shunt circuit is theoretically capabley of, conversion into 2.100 poundsof CUS per minutie, the FeS sup'- plied' would be such as tocause but one ton of `:GllSzzto' form. In this=;Way,-suf1icient is dissolved in thestream'. The object of -this copper sulphate,` thesupplyof FeS to the Aetc. will kpass fromthe agitators back-to the main train at the vessel 7 5. Furthermore, the uselof this limited amount of FeS assures that it will all be used for its intended purpose'and that none'willremain to pass on With and contaminate the CuS, `Which itfis desired shall be pure. The CuSO4 -Which 1s not thus acted upon by the FeS passes back into the main train at 75 and on downl the stream until it meets some sulphide which de'sulphates it. The `CuS thus formed is carried back up-stream to the copper sulphate group of vessels vWhere it is again sulphated. v

The supernatant liquid containing the FeSO4 in solution passes from the vesselB,

vin part back to the main train at7 5 and in partto a storage vessel at 47, While the underfiow containing the. precipitated CuS passes Vinto a thickener 17 and thence to a lilter 18, from Which the filter cake is passed to y.vessels 2O and 2li for treatment with` H2SO4 or SOB, or a combination of both, to Vform substantiallyA pure copper sulphate in solution. c

This is then passed, through a settler or thickener 22, into electrolyticcells 23 to produce pure'electrolyticcopper, as indicated at 24, While thespent electrolyte is returned to the main train ofvessels Wherever required, or is used'to sulphate the CuS in-the vessels 20 and 21, allas indicated.VV AThe filtrate from 18'is passedto'thestorage vessel 47 along with thesolution'fr'om vessel 35.

While the treatment of theCuS fromV the time it leaves the agitator `35is important from an economic viewpoint, the formation of the FeSO in theshunt circuit is more directly` concerned in the method, since it isoneY of the intermediate compounds obtained vin ,changing the lferrous sulphide, FeS, to

ferrie sulphate, Fe2(SO4)3. v The FeSO,l is

i transferred to the'vesselY 47 along with some H2SO4, and air is introduced -into said vessel, as indicated. It sufficient HZSO,V and O are present, the FeSO4 is completely converted into ferriey sulphate. Thus, u (5) j2FeSO+ H2SO4+ O=li`e2 (S04) 3 H2O Since, hoyvever, the acid accompanying the FeSO., hascome from the main train at 76 and is largely spent, itis not suiicient for the complete conversion of Equation (5),' and only a part of the FeSO4 is Ythus convert`ed.

The remaining part isl both oxidized and hydrolyzedintor a basic "sulphate of iron as follows:- Y' l 1 (6) eres'ogesoarzo:

which breaks up into ferrie sulphate'- and ferrie hydroxide, as" appears from the following: v 4 (7) 2Fe, (so,)3(on),=

There is thus obtained from reactions n( 5) and (7) the ferrie sulphate required for oxidizing the ILS; and this sulphate, after filtration at 48, is ledA back into the main train at various points, as indicated, where it reacts WiththeH'zS in -accordancewith Equation (2), which is here repeated:

vILS from. the solventA and to build up the acid therein. Thus isone deleterious substancey utilized in the removalp'of the other and in building up Athe acid; VAs has been suggested, a sulphide in the Ytrain Willnot be-sulphated vif another sulif phide -Which is more susceptible to the' acid attack be present Withit, as the acid will first attack the latter sulphide. This being true, a sulphide which vvouldfotherwise 'be sulphated in a certain vesselof the train can be caused to remain in the sulphide form and toV be carried along'to another part of the train by simply introducing some fresh ore withit.

Referring to the loiv sheet, the-solution,

heavily impregnated'with sulphates of various kinds, passes'from the-vessel 50 into a thickener 39 for removal of suspended and settled inert matter. The clear overoiv from 39 passes to reaction' vessels and .thickeners/l() to 42 in 'which the solution is agitated with'an'other part of the F eS Vfrom 38 l'and' sufcient -H2'SO,A to liberate ILS.

This HZS reactswith'thesulphates of Cd,

As, Sb, and Bi and precipitates them as sulphides. l These reactionsare as follows:

Theseprecipitated sulphides, after yfiltration f at 100, are discharged as a mixed product at 101, as indicated. Y

During the sulphatation of the sulphides inthe train, many reactions occur which, liberate elemental S,.as in Equation (2).

l This sulphur is carried in suspension in the solution to be removed by the filter and `to appear with the mixed products at 101.

The decanted and clear solution from vessels 40 to 42vand ilter 100, containing sulvau fie@

ilo

phates of'iron and zinc, passes into vessels. 43 to 45, Where it is treated With Zinc oxide The iron hydroxide, after fil-tration at`102, is passed as a product to 49, and the filtrate is passed -to 45 for final precipitation of its iron content. f

The Z is introducedt into the vessel43 in a limited amount for the reason that, if

suicient Were usedV to precipitate all. ofthe iron there, some of the Zn0 Wouldr become entangled in the flocculent hydroxide' of iron, would remain With it in filtration and would contaminate the precipitate withV zinc. -To prevent this result,I thicken the first precipitate in vessel 43 and pass the yclear solution to 44, and similarly to 45 for further precipitations by fresh charges ofZnO. In the last mentioned vessel I introduce an excess of.

the Zn0 to remove the last trace of iron from the solution and again thicken and transfer the thickenings, Which'will contain a large amount of Zn0, backinto kthe thickener 43 into Which the oxide was first introduced.

The solution, after beingpuriiiedof-its iron'precipitate by thickeningY and by the filter at 102, is runinto a final thickener`45 and then into crystallizing tanks 103 for cooling. In cooling, ZnSOl crystals are deposited; but the solution With these crystals is` Withdrawn from the crystallizerbefore such sulphates as M11S04, which is more soluble than ZnSOl, begin to deposit. This is further assured by passing the last deposited or the contaminated crystals back tothe firststage of the crystallizer forfredissolving the more soluble crystals,.as MnS'04, thus aiding lyte, containing acid,beingreturnedto theV main process train as indicated. The remaining and lessfpure crystals (ZnSOJI-IZO) arev passed to a dehydrater 108 Where they are heated to drive off the Water of crystalliza= tion, and the anhydrous Zinc sulphate is then passed into a dissociator 109 Where'it isfurther heated, in combination Withair, to dissociate the sulphuric anhydride, S03, from the Zn0.

- In'dissociating the `ZnS4 some of its splits up directly into Zn0 and S03, While the restv of itis alteredinto the basic form 3Zn0.2S03,

*vvhichsplits up into 3Zn0, 2S02 and 0. I

thus obtainsupplies of S03, S02 and 0 .for use yin the train of reaction vessels for generating `ILSO,A and .supplyingfthe heat of formation. The required amount of the Z110, which is left after dissociation of the ZnSOa, is used again in the vessels 43to 45 for pres Y'cipitating the iron content of the solvent,4 as

hasbeen described. The remaining portion of. theZn0 is a by-product of the process. YThe mixed gases are freed of dust at 110, given. a pressure at 111,and that Which is not required in the train process is passed into acid absorbers 112 and manufactured into 1125504, in theknown manner, to appear as a product at 113. g

The hot Water driven off `from the ZI1S04i is utilized in themanufacture of the HSO.; and also as Wash Water for filtration pur,- poses, as indicated. Y

F rom the above it Will be seen that the invention herein disclosed consists basically in the'inaintenance of a body or stream of liquid sulphat-ing material, the strength ofwhich increases from one point to anotherand the transference of the mixedsulphidesthrough said ,liquid toyvardthe-.point of its greater strength, Wherebythe different sulphides are sulphated and dissolved in different parts of the body or stream and from which they may be separatelywithdravvn for individual treatment. This Vbasic principle is broadly claimed herein. Other claims include this basic principle, butv are. limited to steps taken tentsof the sulphates are separated and the latter are fed back into the body or stream or are otherwise used incarrying out the'inven tion. Certain claims which. Were in the application When filed and Which applicant has been required to divide out have now been cancelled Without prejudice to applicants right vto reassert them in a divisionalfapplication`vv or in..divisional applications, tobe j f filed.

Iclaim: f

`1'. The `method ofv separatingithe vmetal' values .contained in mixed sulphide ores which comprises distributingl the sulphides ina flowing streamof sulphating agent in liquid form progressively in the' order of their resistance to oxidation. by said agent,

oxidizing a sulphide of relativelyhigh Aresist-ance to form the corresponding sulphate, dissolving said sulphate vin said agent, fioW- ing the'agent With a portion of the dissolved sulphate therein down stream Where there* is another sulphide which' has less resistance tooxidationto precipitate assulphide the metal content of the said portion of the dissolved sulpliate, moving the precipitated sul.-

pliide back into the part of the stream Where the sulphate wasoriginally' formed, oxidiz ing the said sulphide and dissolving the sulphate thus formed, whereby the. various sull phatesare accumulated in different parts of the stream. i

2. The Ymethod. vof separating the metal values contained in mixed sulphide ores 'which comprises maintaining a iioWing streamiof Yacidulated .sulphating agent iii liquid form With the. acid strength in the` stream increasing in the up-stream direction, introducing the mixed sulphides in comminuted condition into said stream, movingY the said sulphides'in the said stream in a direction which is counter tothe directional vloiv of the liquid, oxidizing the various sulphides When they reach the respective parts of the stream Where the acid strength is sufficient to attack them, thus to convert the sul phides into the corresponding sulphates, disi solving the sulphates in the agent at the parts in the stream Whereqthe respective sulphates Were thus formed,flovving a portion of a dis- Y solved sulphate down stream away fromits Yce point offormation, precipitating as sulphide the metal content of the said portion of the dissolved sulphate, moving Ythe precipitated sulphide back to said point, oxidizing` the said precipitated sulphide and dissolving the sulphate thus formed, whereby the sulphate is accumulated in its. respective part of theV stream. Y

treating said ferrous sulphide to Aproduce fer- -ric sulphate, and introducing the' latter to said body to remove the hydrogen sulphide therefrom. y. J

4. The method of treating mixed and comminuted 'sulphide ores containing primary Vpyrite which comprises introducing said ores intro an elongated body vof sulphating agent in liquid form near one end of the body, caus- .in said ores to traverse the said bod to convert sulphides the-rein. into the corresponding sulphates With the liberation of hydrogen sulphidein said body, removing from the said. body the primary pyrite floating -thereon, dissociating said pyrite to form ferrous sulphide, treating said ferrousV sulphide to produce ferrie sulphate, and introducing the latter to said body to remove the .hydrogen f sulphide therefrom.

5. The method of'treating mixed andV comminuted sulphide ores containing primary pyritev Which connorises maintaining a` iovving stream of sulphating agent in liquid form', introducing the ores into said stream "near the lowerfend Ythereof,-advancing said` ores through the liquid in the up-stream direction, oxidizing certain of the sulphides therein Vinto the corresponding sulphates with the formation Aof hydrogen sulphide, removing the primary pyrite from the stream, dissociating said pyrite to form ferrous sulphide, treating said ferrous sulphide to pro# duce ferrie sulphate, and introducing the lat-A ter int-o said stream to remove the hydrogen sulphide therefrom.

6. The method of-treating mixed and comminuted sulphide Yores-V containing primary pyrite'ivhich comprises maintaining a flowing stream lof sulphating agent in liquid form, introducing the ores into said stream near the lower end thereof, agitating` said ores in the liquid and Vadvancing them through the latter in the up-stream direce tion, oxidizing certain of the sulphides therein into the corresponding sulphates with the formation ofhydrogen sulphide, removing rom thestreain the primary pyrite floating thereon, dissociating'said pyrite to form fer# 1rousrsulphide, treating said ferrous vsulphide to, produce ferrie sulphate', and introducing the latter into said stream VWhere required to remove the hydrogen sulphide therefrom.

7. The method of separating the metal values contained .in mixed sulphide ores which comprises-maintaining a Ylovving stream of acidula-ted sulphating agent in liquid form with the acid strengthin the stream yincreasingin the up-streamdirection, introducing the mixed sulphides in comminuted condition into saidy stream, discharging into said stream jets of acid-forming agents in such manner as to cause the sulphidesin the stream to move in a direction Which is coun. ter to the directional flow of the liquid, oxidizing the various sulphides when they reach the respective partsrof the stream Where the acid strength is Vsufficient to attack them, thus to convert the sulphides into the corresponding sulphates, and dissolving the sulphates in the stream at the points therein Where the respective Vsulphates were thus formed. y S. "The method `of .separating the metal values contained in mixed sulphide ores Which :comprises maintaining a iowingstreamof acidulated sulphating agent in liquid vform' With, the 'acid strength in the stream increasing vin the up-stream direction, introducing the mixed sulphides in comminuted condition into said'stream, discharging intoy said stream jets of sulphuric anhydride in such manner astov cause the sulioo phides in the stream to move in a direction which is counterto the directional iiow of the liquid, oxidizingr the various sulphides when they reach the respect-ive parts of the stream Where the acidv strength is suiicient to vattack them,'thus to convert'the sulphides into the corresponding sulphates, dissolving the sulphates in the stream at the points therein" where the respective sulphates were thus form-ed, withdrawing a sulphate from the stream and treating it to obtain sulphuric anhydridefor use in the said jets.

- 9. The methodof treating mixed and comminuted sulphide ores containing iron sulphide which comprises maintaining a flowing stream of acidulated sulphatingagent in liquid form with the acid strength in the stream increasingin the up-stream direction, introducing the mixed sulphides into said stream, introducing into said stream jets of sulphuric anhydride in such manner as to cause the sulphides to move through ythe liquid in the up-stream direction, oxidizing the various sulph-ides when they reach the respective parts ofthe stream where theacid strengthis suliicient to attack them, thus to convert the sulphides into the corresponding sulphates, withdrawing the iron sulphate thus formed from the stream, introducing into thesaid iron sulphate a metal oxide to convert the iron sulphate into the. iron hydroxide with the formation of the sulphate of the said metal, dissociating the latter sulphate with the formation of sulphuricl anhydride and using said anhydride in the said jets, as and for the purpose specified.

l0. The method of-treating mixed and comminuted sulphide' ores containing iron sulphide which comprises maintaining a iiowing` stream of acidulated sulphating agent in liquid form with the acid strength in the stream increasing in the up-stream direction, introducing the mixed sulphidesv into said stream, introducing into Vsaid stream'jets of sulphuric anhydride in such manner as to cause the sulphides lto move through the liquid in the up-jst-ream directiomoxidizing. the various sulphides when they reach the respective parts of the stream where theacid strength is suicient to attack them, thus toconvert the sulphides into the corresponding sulphates, withdrawing the iron sulphate thus formed from the stream, `introducing zinc oxide into the said iron sulphate to convert the latter into the iron hydroxide with the formation of zinc sulphate, dissociating the Zinc sulphate with the formation of sulphuric anhydride,and using `said anhydride in the said jets to move the sulphides-upthe stream, to maintain the acid strength ofthe liquid and to furnish the heat necessary'to maintain the temperature of the liquid at substantially theV boiling point.

1l. The method ofv treating mixed and comminuted sulphide ores containing sulphide of iron and other less easily oxidized sulphides, which comprises maintaining a. flowing stream of acidulated sulphating agent iny liquid form,-introducing the` said sulphides into said stream near'the lower end thereof,` advancingthe sulphides in jan up-stream direction whereby theyare attacked to form the corresponding sulphates and hydrogen sulphide, dissolving the said sulphatesin the liquid stream `and iowng the liquid at substantially the boiling point.

12. The method Vof Vtreating mixed and comminuted `sulphide yores containing `sulphide of iron, which comnrisesmaintaining a flowing stream vof acidulated sulphating agent, Vintroducing the said sulphides intov said stream near the lower end thereof, advancing the sulphides in an 11p-stream direc tion whereby theybecomev oxidized and form the corresponding sulphates, dissolving the said sulphates in the liquid stream and {iowing them down thestream, treating the mixed sulphates thus produced to. isolate the dissolved iron sulphate, treating the iron sulphate with zinc oxide to form zinc sulphate, dissociatingthezinc sulphate to produce sul phuric anhydride, 4and introducing said sulphuric anhydride into the liquidstreamto maintain the acid strength therein.'k v 13. The method of treating mixed and comminuted sulphide ores for the separation of the metal values contained therein which comprises maintaining a bodyof sulphating agent in liquid form with the acid strength thereof increasingtoward one end of the body, in-

'troducingthe said mixed sulphidesinto the roc n the point where its oxidation wouldotherwise have occurred by introducing into the liquid at that point another'sulphide which is more vsusceptible to the acid attack,-whereby" the first mentionedr sulphide is caused to be carried farther through the liquid and ismore eiiectually separatedfrom the other sulphides in the body.V i

14. The method of treating :mixed and comminuted sulphide ores for the separation of themetal values contained therein which comprises maintaining a'lowing stream of V475 prisesmaintaining Van elongated body of c werefformed and into regionsV where there sulphating agent in' liquid Vform with the acid strength thereof increasing in the upstream direction,'introducing,the said mixed Vsulphides into the stream near the lower endthereof,causing the. said sulphides to move up-stream Vthrough -the liquid whereby theyiare attacked by the oxidizing agent and vthe sulphides are converted into the corresponding sulphates -at those points in the stream wherein thek acid strength is suliicient Vto attack them, dissolving-the sulphates in the stream and preventing the oxidation of any'sulphide at the point-where its oxidation would otherwise have occurred by introducing into the stream at that point ore containing another sulphide which is more susceptible to the acid attack, whereby the first `mentioned sulphide is caused to be carried remains portions of more easily oxidized sulphides, `precipitating as sulphides the metal Vcontents of the dissolved sulphates, returning the precipitated sulphides counter current to the fiow of the stream until the said sulphides are again' oxidized into the respective sulphates,'and repeating the cycle of oxidation, dissolution, precipitation and reoxidation until the-sulphides are fully oxidized andthe dissolved sulphates are separated in the stream.

@16. The methodof treating mixed sulphide ores in comminuted ycondition which comoxidizing'sulphating liquidthe strength of which varies Vgradually from point to point, introducing` said ores into said body where vthe strength of the'liquid is relatively weak, Y Y agitating the f ores Ywithin the liquid and causing them to travel therethrough toward the-,stronger part of the Aliquid whereby the sulphides arev sulphated and dissolved when "they reach those parts of the ,body` where the liquid is strong enoughto attack them, withdrawinga dissolved sulphate from that part of the body" near which the ores were introvduced,vtreating the said withdrawn sulphate toobtain sulphuric anhydride, and introducing' the saidvanhydridei'nto the said body to v maintain the acid strength thereof.

l7fThe method of separating-the metal ,values contained lin-mixed sulphide ores which Vcomprises maintaining an elongated bodyrof- Yacidulated .sulphating material in liquid form in which the acid strength varies gradually from one point to another of the body, introducing thelmixed sulphides in finely dividedcondition intosaidbody where the acid strength isrelatively weak-discharging into said body jets of acid-forming agents in such manner Vas to causerthe sulphides to move toward the parts of the'body where the acid is stronger, sulphating the various sulphides when they reach thev respective parts ofthe body when the acid strength is sutlicient to attack them, and dissolving the sulphates in the body atthe points therein where the Vrespective sulphates were thus formed. Y n

18. The method of treating mixed and comminuted sulphide ores containing copper sulphide which comprises maintaining a flowing stream of oxidizing sulphating material in liquid form with the acid'strength in the stream increasing in the up-stream direction, introducing the mixed sulphides adjacent the lower end of the stream and causing them to move upstream counter to the directional How of the liquid, sulphating the various sul- Aphides when they reach the respective parts 'of the stream wherethe'acid is strong enough to attack them with the formation of HZS`- dissolving the various'sulphates at the points inV the stream where they were Athus formed, withdrawing the sulphate of copper from the stream, introducing FeS into the copper sulphate to produce CnS and ferrous sulphate, treating the ferrous sulphate to produce ferric sulphate, and feeding the ferrie sulphate into the stream' to remove the `ILS therefas from and to strengthen the acid content of the l liquid. Y

19. The herein described method which comprises maintaining an elongated bodyfof liquid sulphating material the acid strength of which increases gradually in one direction, introducing a mixture Ycontaining two'sulphides intoV said material at a point therein where the acidvstrength is sufficient to attack one but not the other of said sulphides, whereby the said one sulphideis sulphated and dissolved, moving the said other .sulphide from the point in the sulphating material where the one sulphate wasV dissolvedfto parts of the material havingy greater and greater strength -until a partis `reached where the strength is suiicient to attack the said other sulphide, sulphatingand dissolving the said other sulphide in that partof the material whereit was thus attacked, whereby the two sulphates are separated thefsulphatingmaterial, withdrawingV the two separated sulphates from their respective parts of the material, treating the. separated sulphatesfor the recovery of their respective metal values with the consequent liberation of the acid-formingv parts of the sulphates, and introducing said acid-formingparts into ythe sulphating matepoint where the said sulphate was dissolved until it reaches a point when the liquid is strong enough to attack it and there sulphating the latter sulphide and dissolving its sulphate in the stream, whereby the sulphates are separated in the stream and made available ior separa-te treatment for the recovery of their respective metal values.

2l. The herein described method which comprises maintaining a flowing stream of liquid sulphating material the acid strength of which increases in the direction of the source of the stream, introducing a mixture of two sulphides in finely divided condition into said stream, sulphating that sulphide which is the more susceptible to the acid attack and dissolving its sulphate in the stream, flowing said dissolved sulphate down the stream, moving the remaining and more resistant sulphide up the stream from the point of its introduction until it reaches a point when the liquid is strong enough to attack it and then sulphating the latter sulphide and dissolving its sulphate in the stream, whereby the sulphates are separated in the stream, ,treating the separated sulphates for the recovery of their respective metal values, and injecting the acid contents of the sulphates into the stream to move the more resistant sulphide therein and to maintain the sulphating strength of the liquid.

22. The herein described method which comprises maintaining a flowing stream of liquid sulphating material, introducing a mixture of copper sulphide and iron sulphide in the form of FeS2 into the stream, said sulphides being in a finely divided condition, moving the copper sulphide in the stream into a Zone where the strength of the sulphating material is suiicient to convert it into the sulphate of copper, dissolving the sulphate of copper and removing it from the stream, removing the leS2 from the stream and heating it to convert it into FeS, introducing the FeS into the copper sulphate to convert the latter into FeSO4 and CuS, removing the' CuS, treating the FeS04 to form Fe2(S04)3 and introducing the latter' into the stream.

23. The herein described method which comprises maintaining a body of acidulated sulphating material in liquidform the acid strength of which varies from point to point `in the body, introducing mixed sulphide ores in comminuted condition into said body at a point Where the acid strength is relatively weak, moving said ores within the body until the various sulphides reach respective points when the acid is strong enough to attack and sulphate them, whereby the sulphates are separated in the body, dissolving the sulphates at thepoints where they were thus formed, withdrawing a sulphate from the body, treating the withdrawn sulphate to obtain sulphuric anhydride, and introducing into the bodysuch part of the sulphuric anhydride as is required to maintain its acid strength.

24. The herein described method which comprises maintaining a flowing stream of liquid sulphating agent the acid strength of which increases in the up-stream direction, introducing. a mixture of sulphide materials into said stream adjacent its lower end, said materials being in comminuted condition and containing copper sulphide and FeS2, moving the various sulphides up-stream until they reach parts of the agent which are respectively strong enough to attack and sulphate certain of them except the FeS2, withdrawing a sulphate from the stream and treating it to obtain S03, removing the FeS2 from the stream and'heating it to form FeS, withdrawing the copper sulphate from the stream, introducing FeS into the copper sulphate to precipitate the copper content as CuS, introducing part of the S03, produced as above, and air into the CuS to change the latter to 0uS04, and introducing the remaining part of the S03 into the stream to strengthen the acid content thereof.

25. The herein described method which comprises maintaining a flowing stream of liquid sulphating agent the acid strength of which increases in the up-stream direction, introducing a mixture of sulphide materials into saidstream adjacent its lower end, said materials being in comminuted condition and containing copper sulphide and FeS2, moving the various sulphides up-stream until they reach parts of the agent which are respectively strong enough to attack and sulphate certain of them except the FeS2, withdrawing a dissolved sulphate from the stream and treating it to obtain S03, removing the FeS2 from the stream and heating it to form FeS, withdrawing the dissolved 0uS03 from the stream, introducing F eS into the CuSO4 to form FeSO4 and precipitate the Cu as CuS, introducing part of the S03, produced as above, `and air into the CuS to change the iso

Images