Патент USA US2122197код для вставки
June 28, 1938. ' . F. |.. DUFFIELD PRODUCTION OF IRON FROM IRON ORE Filed May 4, 1937 k / Q) 2,122,197 ' 3 Sheets-Shegt l ‘ ‘June 28,1938. F-L-DUFFlEl-D , ' 2,122,197 PRODUCTION OF IRON FROM'IRON ORE Filed may 4, 19s? . 3 Sheets-Sheet 2 June 28, 1938- 2,122,197 F. L. DUFFIELD PRODUCTION OF IRON FROM IRON ORE . Filed May 4, 19:57 ‘ 3 Sheets-Sheet 2» Patented June 28, 1938.’ I I - - I eUNiTED STATES PATENT, OFFICE ‘Frederick Lindley Dumeid, London, England ' Application May '4, 1937, Serial No. 140,618 . In Great Britain May 6, 1936 2 Claims. (Cl. 75-1-29) , This invention relates to the production of iron from iron ore. - ' - \ cient to cause the slag to become viscous, with ' attendant wail adhesion, it ?oats on the surface , Existing methods for producing, molten‘ iron of such slag, and in that position exposes its car of high purity are founded on the principle of, purifying the crude product of the blast furnace» bon contents to oxidation by the furnace gases, such carbon thus faiiingin its .intended duty of 5 by treatment in the Bessemer or open hearth fur- reduction of the iron oxides. naces. The object of the present invention is to I obtain pure iron (99.84%) directly from the ore, thereby avoiding the inclusion of impurities these defects which operate'against the practical accomplishment of producing an iron conglomer @ which entail subsequent elimination by re?ning methods. ' It has been found by experimentation that ate or matter direct from the ore can be over-g m ' , come by the present invention. _ In the past the production of so-called sponge - According to the present invention the iron iron, i. e._ iron produced at temperatures below ore is mixed in a granulated state with carbo fusion point, has been attempted to secure a base ' 1111060118 material, moulded _int0 blocks,‘ Slabs, w of high purity which is intended for melting in briquettes or other shaped bodies and charged“; some suitable kind of furnace. Great difficulty has been experienced in producing sponge iron in a practical manner, and the applicant has found that even if economical 20 production "of sponge iron were accomplished, into a furnace heated interiorly by combustion so that they fall into and are submerged in a bath of molten slag contained in said furnace, where by the slag constitutes a protective coating for the shaped bodies, ‘protecting them against the 20 the product, due to its powdery state and low conductivity due to excessive porosity, is an’extremely inconvenient and 'dif?cult material to oxidizing atmosphere of the oxidizing gases in the furnace, and the reduction proceeds Within the slagv coating by reason of heat absorbed melt e?lciently in any kind of furnace. from the slag,’ whereupon the ore is reduced and 25 >‘ One of the advantages claimed in the produc- the iron Particles drop to the bottom and coa- 25 tion of sponge iron as an intermediate product lesceand can be removed from the furnace in for molten iron and steel production is its adaptability for concentration ,of its iron contents by the form of relatively-large masses of semi molten "on with some included slee magnetic separation. ‘The applicant has found ‘ l The Slag can he removed from the iron mass 30 ‘from long experience that the iron contents or .\ discharged from the reductiolrchamber by sub- 80 the majority of- ores is so intimately physically “sequent treatment in an electric or other fur combined with its gangue matter that the naceieltematively the slag may be'removed by a latter becomes entrained in that which is mag- , mechanical Squeezing pl‘oces? netic, and no su?icient elimination of the orig35 inai gangue matter of'the ore is achieved to rén- The process may be carried out in apparatus comprising’ an oscillating furnace provided with 35 der the process‘ serviceable~orfpracticable.U - a (1001‘ for the discharge of the reduced metal, it There havegbeen ‘attempts in" the past to re- taphole for discharging slag, means forcharsine duce and melt or semi-melt iron ore in rotary the furnace, means for admitting heating gases furnaces, "but by long "égpe'?ence it has been 40 found that certain salie'nt‘principles‘ are nece‘s- into the furnace and an additional air inlet adja cent to‘the exit" ?ue forJthe ‘heating 3945,95» this 40. any ‘for ‘its; practical"v and ‘economical ‘accomplishment: . ' I _ I I t ,_ I’ ‘ i t.¢'-:i _Wh_en granulated vor. p0 ' red iron ore: vis <45 m'xed w -h' ‘5 reqmmdquanmy of granulated last an‘ ‘inlet ‘being arranged solthat the 9/11’ ad‘ ‘ zniigedt‘thfez?by haste/direction which is" opposed O a (II e'Ou 8 38.565. "'5 " 3' ' " The furnace should be of squat shape, that‘ is to ‘say the length» should not exceed three times 45 ior p‘o'wde‘rqq ppm topmduqtiqn’ whet-ha firstly the diameter so that in; this way a: substantially lr-‘iaduce-q"bx'heat-m-‘ied idireg?yinto‘“rotary ' uniform-1temperature?sufficiently-‘highto‘lmainn no furnace, upon semi-fusion it adheres to the side tam the 515g in a‘v'k?uid state‘can'be ‘maintained wallsof the revolving»,;furnace, incurring maxi- lthrd?ghou?thefumace expqsurejto. the. effect- ofrthe vxidlzinglrfur- ' e l =: ~ ' -. a I ' ‘The-invention " ill te-oestnteafwnn reierenee- to, nece sasestiwhich bum :thetcoal-which:haswbeen to the accompanying" drawings?'which'tillustrate added =_for; thelpu-rpose of ?lling “itstfunction‘of one formiof apparatus‘ which‘ may bewusedvfor ~reduction,~and<a:poorrresultis: Evendfj fed/upon. abath bf-rmoltenslag inevitable.atlsuch ‘ carrying; .Fig. llillustrates out‘ the, ainvention, vertical sectionlofvthe .1; . appa ‘55 -a-=-rat,eqthat its-urapid"heatiabsorption;iscinsu?b ratus; - 3 2 2,122,197 all times throughout the period of operation is Fig, 2 is a plan view; and . Fig‘. 3 is a central ‘cross section. to enable the reduction of the iron oxides by ' The oscillating furnace at has a length about ' carbon to proceed and be completed at the low temperatures, regulated by the conductivity of twice its diameter and is mounted for rotation on rollers b, b. “Fuel consisting of coal dust and ' the thickness of the mass constituting the block 5 air is admitted tangentially through aperture c 0r,-_briquette. and additional At temperatures ranging between 1150° C. and 1400" 0. fusion of the oxides of iron in combina tion with silica is effected, producing ferroussili- I cates, so that little or no practical reduction by 10 air is admitted tangentially through aperture d arranged in a‘cylindrlcal end chamber e. The other ehd of the furnace is pro 10 vided with a main charging passage 1 and an auxiliary charging passage 9 arranged in the wall of the charging passage ,f. The passage f also constitutes an exit ?ue for the gases of- combus tion, and is completed by a movable ?ue k mount 15 ed on rollers so that it can be moved away’ from the passage i when it is desired to charge through this passage. An auxiliary air jet Z is provided carbon takes place, since silica at such tempera tures has a greater a?inity for iron oxides than ' carbon. Consequently unless the oxides of iron are reduced at temperatures below their fusion point, as provided by slow heat penetration of the 15 block or briquette, a preponderance of reaction is in the formation of ferrous silicates. Thus if ’ granulated ore andvcarbon were fed in a loose ' in the wall of the passage 1'. and is directed towards the interior of the furnace, i. e. in a direc- , (non-briquetted) state on to a ?uid slag, the re tion which is opposed to that of the exit gases. A discharge door m is provided in the wall of the furnace remote from a tangentially disposed tap hole n for slag. l‘ - spective particles of iron oxide and carbon would 20 fall in their desired reaction, the iron oxide’com bining with the silica present in the slag and the carbon being lost by the oxidation of the furnace ' In order to carry out the process according to 25 the present invention the iron ore to be reduced is granulated and mixed with a corresponding quantity of granulated carbon sumcient to effect the reduction of the iron oxides and attendant moisture, and is pressed or moulded into blocks 30 or briquettes with a suitable binding agent. The binding agent may beomitted if desired, as it is gases. , - At temperatures higher than 1400° C. ‘the fer- 25 rous silicates dissociate=\ if su?cient carbon and lime be present, and metallic iron is precipitated, but the formation of ferrous silicates is un-' desirable, ?rstly because of their erosive e?ect on any furnace lining, and further the metallic iron :80 thus precipitated has not that purity that is ob tained by its direct reduction at temperatures .below its fusion point. To retain theslag in a state of ?uidity advantage is taken of the low rate of heat transfer to the block or briquette, ‘B5 not absolutely essential in themoulding oper ation. “ Slag is" introduced ?rst intothe furnace and is heated by admitting burning gases from the inlet apertures c and d until the slag is molten. This ‘ and the rate of feeding the charge is regulated molten slag forms a liquid bed on the bottom of» to coincide with the heat supply. the furnace into which the moulded blocks are As the reduction proceeds the blocks disintev-e introduced by charging either through the charg grate/‘and the iron particles drop to the bottom ing passage f, if the movable ?ue k is removed, or through the charging passage 9', if the movable ?ue k is in the position shown in Fig. 1. The momentum of the blocks or briquettes as they are charged into the furnace causes them momen-' of thefurnace and coalesce into one or more r40v masses. When thereduction is ?nished the slag is first drawn off through the taphole n and the masses of coalesced iron particles are subsequent ly discharged by gravity by rotating the furnace tarily to be fully submerged ‘in the molten slag, so that gravitation is lowermost. which adheres to the colder surface of the block quantity of slag is then reintroduced into the fur or briquette and providesan enveloping protec ‘nace and the processis continued with a new tion against oxidation. a charge. ' The low conductivity of the block or brlquette, by reason of its thicknesscompared with small It is essential that the'slag should remain ?uid, vand this is assisted by the slower uptake of heat which, in gradually penetrating the blocks or bri quettes, effects reduction of the oxide contents at low temperature which is controlled by the limits 60 of its low conductivity. Complete reduction is effected by this gradual heat penetration without disturbing the equilibrium ofheat supply and demand of combustibles and ?uid slag respec tively. , ‘ . By making the furnace of relatively squat shape, that is to say not too long relatively to ' ‘blocks in process of reduction are burned before '50 leaving the furnace by means of the auxiliary sudden and rapid absorption of heat which would render the receiving bath of slag surllciently vis cous ‘to adhere to the walls of the furnace. ' The combustible gases which emanate from the granular pieces of ore and coal, prevents a too 751 A sufficient :45 air admitted through the air jet l, which helps to maintain the required temperature at the outlet ._ endof the furnace‘. . . a , _ in a- recuperator or regenerator with theheat of the combustion products after leaving the oscil lating fiu'nace, either prior to or after such com bustion products have been partially used for cal- '60 cining or drying the ore before being formed‘into , briquettes. . The oscillating furnace shown in the drawings rotates approximately 270° in’ one direction and then through a corresponding angle in the re- 65 verse direction. Other forms of furnace may be its diameter,_the slag melting temperature is re tained throughout the whole length. If the length of the furnace were too long relatively to its width it will be evident that the temperature at the outlet end of the furnace would fall below that required 'for making and maintaining the slag fluid, so that the latter‘ will adhere to the used for carrying out the process according to the wall of the furnace and thus cause obstruction. cording to the present invention readily yields to ' _ All the air admitted through the various air in- ‘55, lets may be pre-heated, for example by contact invention. ‘ It has been found by experience that whereas sponge iron presents the utmost difficulty in melt- 70 ing in the electric furnace by reason of its poor heat conductive power caused by its excessive porosity, the conglomerate mass obtained ac Another reason for keeping ‘the slag ?uid at _ the heat of the electric furnace, and a rapid melt’rglsi... ( 2,122,107 _ . 3 ensues with e?‘icient separation of the molten - against the oxidizing atmosphere of the oxidizing metal and the minimum of metallic inclusions in gases in the furnace, and the reduction proceeds within the slag coating by reason of heat ab the slag. v ' ' What I claim and desire to secure by Letters sorbed from the slag, whereupon the'ore is re duced and the iron particles drop to the bottom Patent is:' > 1. Process for- producing iron from iron ore and‘coalesce and can be removed irom the fur nace in the form of relatively large masses of which consists in mixing‘the iron ore in a gran semi-molten iron with some included slag. ulated state with carbonaceous material, mould 2. Process, according to claim 1 further con ing the mixture into blocks, slabs, briquettes or 10 other shaped bodies and charging the said shaped sisting in admitting a separate supply of air into the furnace in a direction opposed to that of the bodies into a furnace heated interiorlyiby com bustion so that they fall into and are submerged outlet gases for burning the gaseous reaction in a bath of molten slag contained in said fur nace, whereby the slag constitutes a protective 15 coating for the shaped bodies, protecting them products resulting from the reactionbetween the iron ore and carbon of the blocks or the like. FREDERICK LINDLEY DUFFIELD.