[1]ITM Vi,ilTED STATES PATENT OFFICE. FREDERIC A. EUSTIS, OF MILTON, MASSACHUSETTS, ASSIGXOR Or THREE-FOURTHS TO CHARLES PAGE PERIN, OF NEW YORR, N. Y. TREATMENT OF IRON ORES. Specification of letters Patent. Patented illay 10, 1921L. No Drawing. Application filed April 27, 1920. Serial No. 377,006. To all ichoi?@ it iizay co@icem: Be it knoivn that 1, FREDEitic A. EUSTIS, a citizen of the United States of America 2 and resident of Miltoi-i, in the county of Norfolk ancl State of Massachusetts, have ini-ented new and tiseftil Improvements in the Treatment of Iron Ores, of - %Yhich the folloin-ing is a specification. This iiivention relates to the treatment of 10 iron ore, ai-id particularlv fine iron ore, and its I)rincil),,il object is to produce an electrolytic iron direct from the ore, without sinteriiig or siiielting and often without roast. -Otlier objects are to procluce artifici,,tl ln(r. 15 gypsuin as a by-prodtict, aiid also certain incident,il metals, such a's aluminum, manganese, nickel an(! ebromitim if these met,,tls are present in the ore. The worcl " (Y-,,i)stin-i " as used throughout 20 the specification ,ind claims denotes an artificiallv prepared (,,i,])stim -,vliich has the saiiie'eliemical symbol (CaSO,+2H20) and the sqme ei-i@st@illine foi@m as -.vpsum found in iiitiire. 25 The inn-eiitioii is well adal)ted to the ti-eatment of sucli ores as the soft iron ores of the iiorth coast of the lsl,,iiid of Cuba, -%vhicli oceiir as blanket deposits on top of the rocks foi-ming that part of tl-ie island. 30 The ores consist essenti@(iII3, of oxids and silicates of iron and aliiminum, and contain also small amounts of nickel, mananese an(I chromitim to etlier with mucli water Sucli ores liave the a(IN-antage for the pres35 ent I)i@ocess tb@it tbev do not have to be cyround. Btit the process is ,tlso applicable to otlier fine ores, qs well as said Cuban ores, ivlictlier tliev are fine iii iidtiire or are made fine I)v (Yrindin,(,. Such ores as the Cuban 40 ores ci 11 be treate(I bv the present method -%i-itlioiit roastincr. Tf, ho-%vever, the ore does iiot yield rea(lilv to the solvent it niay be (ril-eii ti I)i,elimin,,trv stiltable roast to make" the ii@oii aiid oiber iiicidental metals 45 ,iltiiiiiniiiii. man,)-aiiese and nickel, if preseiit. i-ea(lllv soluble. The fiiielv dii-ided ore is first leached in a stiltal)le lixii-iatinvat. The soliition used is a \ve,,ik solutioii of hvdro50 cliloric- or i iiiixti,ire of h%-droefiloric acid ind stilfuric ,icid. I)tit otl@er suitable solveiits -"- Iiieli will act as aii electrolvte at a 1,,iter sta,re of the process may be used. The leaching step yields on the one hancl a liquor containing in solution iron salts 55 an d also aluminum salts, and nickel ,ind m an (,Iranese if the latter metals were present in the ore; and on the other hand a residlie co nsistiiig of substantially all the silica and siib stantially all the cliromium (if present) 60 toether with small amoiints of undissolved iro n and small amounts of tlle other metals if present. The residue may be treated as wa ste, or used as a source of chromiurn if de sired. 65 The liquoi- is now subjected to a redticing treat ment. This can well be done by adding SO, gas in the presence of calcium carbona te -(CaCO,) in the manner more fully set forth in my applic,,ition for Letters Pat- 70 ent of the United States filed '-@'ovember 3, 1919, Serial --\-uiiiber 335,453; but any other econ omical metbod of reducing ttie soltition may be used. After the reduction step any calcium sul7 5 fate ii-Iiieli ma)7 have been precipitited slaoii ld be filteri(I out in order to make t clear liqtior. CAlcium sulfite is soluble and '%Vi ll stiv in the liquor, but calciiirn sulfate is insoltible and should be removed. 80 F ineli, (,Yroiind limestone, or calciiim carbona te (CaCO,) is then -,i(lcl'ed to the reduced and filtered liquor in siiflicient quantitv to prec ipitite siibstantially all of the alumini, Anlferi,ic iron present will come clowii with 85 but there will be only sli(rlit the ,ilum@na, tric es. if anl-, of ferric iron, and the imotint ma v be furtlier minimized'by the ad(lit'lon at tbis.stel) of a small amount Of sulfur dio xid (SO.,) to supplement the siilftir 90 dio xid alre,,i(IN, present in the solutioll froni the rediietion stel). Tlie rest of the iron in the solittion is ferrous ii,on which is tllorou o,,Iily redticed, and will iiot I)e precipitated bv the calcium carbonate. 95 The I)recipitate fi-om the last step i.-, suit able material for, treatniei-it I)v the B,.iver pr ocess or otlierwise to I)i@o(iiiee piire -111tiTiiinu m oxid: ivliile the liquor contiins silts of ferroiis iroii and Iline aii(I of stich of the ir) o oth er iiietals. nici@el oi@ ni@in(,,,inese is m,,iv ha ve beeii presen'L In the oi,e. I nto this soltition there is tlieii introdiieed a soliition of f(,i-roii@, stilfate (FeSO,) sliffici ent ii-i qiiantitv to precil)it@it(, the Iiine 105 pr esent as calcium stil'Late (C,,iSO,21-1,,O) or
[2]gypsum. The ferrous sulf ate used at this step i-nay be obtained from any suitable source but is preferably produced as hereinafter described by treatment of some.,of the same kind of ore which is being tteated in the main process. The calciiim sulfate thus precipitated out may be iiorked tip and marketed as gypsum. The liquor, now containiiig salts of fer10 rous iron, and of manganese and nickel if present, is then coneentrated in an evaporator, if desired, to reduce the quantity of water; and the concentrated liquor is then subjected to an electrolytic treatment. Me15 tallic iron will. be precipitated in the electrolytic apparatus at the cathode and manganese (if present) will be precipitated at the Anode as a dioxid. The precipitation will not be carried to completion but -,vhen 20 a slight amount of acidity has been built up by the reaction in the electrolytic apparatus, the electrolyte m,ill be rettirned to the ore vat at the first stao-e to be used as a solvent, and added to the leach liquor, thus complet25 ing tha cycle. The electrolyte so returned will again pass throti(rii the process and be ao,ain subjected lo the treatments ,ilready described. As an alternative metliod to the treatment 30 of all bf the solution resulting fi,om the leacliinu step for the purpose of preeipitating ali@mina, the soltition may be dii-ided into t-%Yo parts before the precipitation of the altimina. by 6alcitim carbonate, and pi@ef - 35 erably aftei@ the reduction step. One part Tay be treated, as already described for precipitating altimin,,i and recovering gypstim, wliile the other part may be carried direct to the electrolytic cell 'v@liere it is i-etinited 40 with the part of the.liqtioi- from whieh the ,iltiminum li,,is been precipitated. Tbus part c)f the soliition is short-eiri@uited aroiind those ste@s by whicli 41iimina and ovpsiim ,ire pioduced, and is stibjected dir;@tlv to 45 the electrolytic treatment. The steps ot recovering alumina and gypstim -are not essential io the recover@v of ii-on, and the main piirpose of those steps (apart from the recovery of iltimin,,t and gypsum for their 50 own sake) is to avoid an excessive amount of altimina in the solution-too much altimina is troublesome in the later treatment while ol ,t little may e%-en'be advanta eous. Therefore, it is not nece'ssarv that' the altimina 55 should be removed from all of the solution before the electrolvtic treatment. The omission to treat pait of the soliition foi- the recoverv of alumina will proi-e advantieotis and 'economical partictilarlv whent@ the 60 voltime of liqtior is i-erv Itiro-e. If the ore i@ on.e wbich reqtiires considerable aciditv iii the solvenl - it mav be desirable to use' an electrolvtic cell w'ith a diiphragm to keep the 'acid formed at the 65 anode away from the@cathode, If t very 1,377,822 sliglitly acid solvent will suffice this may not be necessary. A-ain, with some ores it ivill be -,idvaiitageous to use two reduction steps in eaell evele; one after the leacliincr of the ore as 70 already described, and another between the electrolytic step and the leaching step to reduce the electrolyte, If the reduction of tiie electi,olyte is performed in a rediietion to-wer sucli as described in my said application 75 filed November 13, 1919, Ser. No. 335,453, acid will be generated from the sulfur dioxid in the process of reduction. The acidity of the eleetrolyte may be increased in this manner two I)er cent. or more. 80 If nickel is present in the ore it will be dissolved in the leachina step with the iron, and -with alumina aiid-manganese, if present, and ivill be precipitated in the cathode. part of the electrolytic cell either as an allo@' 85 with the iron or as a sludge, depending ori the detail control of the electrolytic operation. The ferrous sulfate added to the solution tfter the precipitation of the alumina. may 90 aq already stated be obtained from anv suitable souree, but it can conveniently 'De made by leaehing some of the ore with a stron(y solution of SO, in water. This leaching yields a residtie of silic,,t and of 95 cliromium, if present in the ore, and a, solution of ferrotis sulf ate (FeSO,) together with sulfates of aluminum, ma-uganese and nickel if those metals are present in the ore. The small amotint of aluminum, if any, in- 100 troduced at this stage will be returned -with the solution to the original leacli liquor, ,ind will come out in the -next cycle.. The resiclue from this leaebing step for making ferrous sulfate, or the residue from 105 the first leacbing step'of the main process, mty either of them, in case it is unduly foul -witli iron, be ptit@ back into one of the leachin vats for retreatment to clean up the iron.
