US2971703A - Process for cleaning and recovering scrap metal from slag and the like - Google Patents

Description

Feb. 14, 1961 F. E. RATH PROCESS FOR CLEAN 2,971,703 ING AND RECOVERING SCRAP METAL FROM SLAG AND THE LIKE Filed June 4, 1958 13 Sheets-Sheet 1 @Nl QNUNIf F. E. RATH Feb. 14, 1961 2,971,703 PROCESS FOR CLEANING AND RECOVERING SCRAP METAL FROM SLAG AND THE LIKE 13 Sheets-Sheet 2 Filed June 4, 1958 F. E. RATH Feb. 14, 1961 2,971,703 PROCESS ECR CLEANING AND RECOVERINC SCRAP METAL FROM SLAC AND THE LIKE 13 Sheets-Sheet 3 Filed June 4, 1958 mmm.

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Feb. 14, 1961 F. E. RATH 2,971,703

PROCESS Foa CLEANING AND EECCVERINC SCRAP METAL FROM SLAC AND THE LIKE Filed June 4, 195e 13 Sheets-'Sheet A"4l INVENTOR: FRA NK E RA TH LM, mamy/M Feb. 14,l 1961 F. E. RATH 2,971,703

PROCESS FCR CLEANING AND RECovERING SCRAP METAL FROM SLAG AND THE LIKE:

13 Sheets-Sheet 5 Filed June 4, 1958 INVENTOR.- FRA NK E. @A TH We M 24% Hfs ,4 TTDR/vsrs. A

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Feb. 14, 1961 F. E. RATH 2,971,703 PRCCCss FCR CLEANING AND RECCVERINC SCRAP METAL FROM SLAG AND THE LIKE Filed June 4, 1958 1.3 Sheets-Sheet 6 IIL?. 4A

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PROCESS FOR CLEANING METAL FROM SLA Filed June 4, 1958 13 Sheets-Sheet 7 INVENTOR- FRA NK E. RA TH H/SATTORNEKS'.

Feb. 1 4, 1961 F. E. RATH 2,971,703

PROCESS FOR CLEANING AND RECOVERING SCRAP METAL FROM SLAG AND THE LIKE Filed June 4, 1958 13 Sheets-Sheet 8 Ffm 6A INVENTOR.' FRANK E. PATH HAS' ATTORNEYS.

Feb. 14, 1961 F. E. RATH PROCESS FOR CLE 2,971,703 ANING AND RECOVERING SCRAP METAL FROM SLAG AND THE LIKE 13 Sheets-Sheei'l 9 Filed June 4, 1958 MAGNET/C fla. 7

Feb. 14, 1961 F. E.`RATH 2,971,703

PRocEss FOR CLEANING AND REcovERING SCRAP METAL FROM SLAG AND THE LIKE.

13 Sheets-Sheet 10 Filed June 4, 1958 /m/E/vro FRA NK E. @A TH ga, ha@ d Feb. 14, 1961 F. E. RATH PRocEss RoR CLEANING AND REcovERIRG scRAP METAL FROM SLAG AND TRE LIKE 13 Sheets-Sheet 11 Filed June 4, 1958 FIGLI Feb. 14, 1961 A F. E. RATH RRocEss RoR CLEANING 13 Sheets-Sheet 12 Filed June 4, 1958 mmm.

NWU NSS@ NX9 m, WS N @NNIPQHBNI Feb. 14, 1961 F. E. RATH PRocEss Foa CLEANINGv AND RECOVERING SCRAP METAL FROM SLAG AND THE LIKE 13 Sheets-Sheet 13 Filed June 4, 1958 MUNI MNNHI United States Patent O PROCESS FOR CLEANING AND RECOVERING SCRAP ll/IETAL FROM SLAG AND THE LIKE Frank E. Rath, 724 E. Brady St., Butler, Pa.

Filed June 4, 1958, Ser. No. 739,823

16 Claims. (Cl. 241-24) This invention relates to the selective recovery of materials from metal bearing refuse and debris, and particularly from slags, which are produced by steel plants in connection with the operation of steel producing units, such `as basic open hearth, duplex, Thomas, Bessemer, oxygen blow or electric steel melting and refining furnaces or converters. It deals with the recovery of both magnetic and non-magnetic metals and high iron content magnetic materials from open hearth ush or runoff slags, open hearth tap or finishing slags, electric furnace or other steel producing slags, as well as from soaking pit bottom materials, rolling mill debris, or mixtures of all of these materials.

This application is a continuation-in-part of my copending application, Serial No. 674,255 of July 25 19,57, now forfeited, which is a continuation of my now-abandoned application, Serial No. 379,009 of September 8, 1953 of the same title.

,The procedure is etlected in such a manner that, for the first time, a substantially complete recovery of the magnetic and non-magnetic metals, and magnetic metal oxide content is accomplished. The materials thus re,- covered are separated, concentrated, and produced in such a clean and uncontaminated condition as to` enable their :re-use in the steel plant at a location where their maximum economic value is realized.

Thus, an important phase of my invention deals, with the progressive and selective recovery and separation of valuable materials (value content) from steel plant slags and other refuse materials, based upon the `size range and physical nature of the materials being processed, 4

upon their malleable as distinguished from frirable nature, and upon their magnetic and non-magnetic properties.

The near-exhaustion of the relatively pure, high grade iron ores of the Hibbing range in Minnesota, the scarcity. of new, large domestic ore bodies, and the increasing cost and national defense factors of scarcity,shipping distance, screening, concentration, etc., of both foreign and domestic iron ores have all made. the recovery of the valuable metal and metal oxide content of slags and steel plant debris animportant matter economically, and also from the standpoint of national defense and the conservation of natural resources.

Heretofore, recovery of valuable materials from slags and steel plant refuse has been limited to attempts at recovery of magnetic metals. ln the steel plants this is accomplished by a simple magnetic separation in the pouring pits and cinder yards of the steel producing unit, wherein the larger pieces of solid metal (generally in excess of 12 inches) are removed and after rough cleaning at a ball-drop are remelted in the steel producing unit or used as charge material in a blast furnace. Any 65 incidental recovery of smaller magnetic materialsv is (be.- cause of contamination) almost invariably directed to the blast furnaces for re-use. In recent years a more intensive eort has been made to recover additional metallics at the waste refuse dumps of the steel plants, 70

after most of the relatively large pieces of scrap VmetalL ?aten ted Feb. 14, 196i have been removed in the steel plant. Such metallics as are currently recovered at the slag dumps contain pieces of magnetic metal badly contaminated with slag, as well as quantities of magnetic open hearth slag and other impurities which limit the re-use of these metallics to the blast furnaces except for a limited amount of large metal pieces. In many instances these recovered metallics are so badly contaminated that material below say lV inch in size must be screened out and discarded in order that the'remaining material be acceptable in quality v even for re-use in a blast furnace.

inasmuch as a blast furnace is a preliminary smelting and reducing unit which provides metallic iron in a molten or solidified condition (pig iron) to the open hearth furnaces for refining and final production of steel ingots; it should be noted that, in addition to the loss of metallics which occurs in present processes (by a limited recovery of the metallics present in the refuse and by discarding under-size material), there is a further economic loss due to the necessity of re-using this -material (because of contamination) in a blast furnace rather than by remeiting it in an open hearth or other Steel producing unit.

There is no process available today which enables substantially complete recovery of the valuable materials present in steel plant slags and refuse or which provides products of satisfactory quality. For example, no method is currently available which enables recovery of nonmagnetic metal, or separation of magnetic metals and magnetic slags, except by hand picking or sorting. Few if any, of the procedures used today produce ordinary steel scrap in sizes below l2 inches clean enough to justify re-use` of this metal in an open hearth or other steel producing unit, or is there any method available which controls the contamination in metallics prepared for blast furnace use.

My investigations have shown that a large amount of the material discarded in present processes as non-magnetic contains an appreciable quantity of valuable metal that is enclosed, bound, or carried by non-magnetic slag or cinder pieces, and which from an economic standpoint, should not be wasted. In this connection, particularly with regard to open hearth ilush or runoii slag, various'sized pieces of magnetic metal may be carried within a piece of flush or runoff slag and because of their location and embedded or bound relationship, or the relatively smaller proportionate size of the magnetic metal piece in comparison with the size of the non-magneticr matrix or embedding material, cannot be picked up by ordinary magnetic separation means such as an electroo magnet. Open hearth tap slags containing substantial quantities of re-usable magnetic iron oxides are also lost in a similar fashion.` The possibilities of recovery from this standpoint are tremendous and, as l have determined, actually predominate as to the recovery that may be effected from steel plant slags or debris.

Steel plant slags and debris, such as are here being considered, will consist primarily of basic open hearth slags. Basic open hearth slags consist essentially of two types of slag: (l) flush or runol slag, and (2) tap or finishing slag. The flush or runoff slag is a tough, porous, essentially non-magnetic slag with a high phosphorous content containing pieces of entrapped steel, varying in size from 1A; of an inch and smaller up to 6 and 8 inches or larger. By contrast, tap or finishing slag is a rather friable, dense slag with a relatively low phosphorous content which varies in iron content and magnetic characteristics from moderately magneticto very highly magnetic and with no entrapped metal particles as such. Also, I have discovered small fragments within a given piece, of tap slag will vary widely asV to their iron and phosphorousV content `and magnetic characteristics. in

addition to these two slags as such, there will also be pouring side cleanup material from the open hearth, consisting of mixtures of both types of slags plus steel spills that occur in the course of furnace tapping, ingot teeming' and slag runois. An incidental amount of refractory brick will also be encountered in this cleanup material from ladle and furnace linings.

Depending on the -particular steel plant, Bessemer, Tho-mas, Oxygen Blow, and Duplex furnace or converter slags may also be encountered together with slags and bottom material from soaking pits and reheating furnaces, and refractory materialsrfrom furnace rebuilds, all of which contain steel and magnetic iron oxides. The other types of steel producing slags and debris are similar to open hearth slags except that pouring pit cleanup from an electric furnace plant may include a certain amount of non-magnetic stainless steel scrap. v 1

The steel producing slags and other steel plant debris as described have 'little value for any known purpose, except for use as fill material, but certain of the components have a very definite economic value if they can be properly separated and cleaned.

The total economic value ofthe various constituents depends not only on the separatio-n of the valu-able constituents of the mixture from undesirable contaminants but also on the completeness of their separation from one another. For example, stainless steel' scrap has a very l pick-out removal of obvious, large pieces of metal in the vre-used, to the extent that their physical size permits,

directly in an open hearth or electric steel melting furnace; Y

Another object has been to develop a process or procedure which will enable recovery of all or substantially Y all of the smaller steel particles which are embedded in open hearth liush slags and other steel plant slags and debris, and to clean and purify these recovered metal particles without loss or size reduction;

A further object of my invention has been to develop a process which will recover and concentrate high iron and high value for melting in an electric furnace to produce stainless steel, but if this scrap is mixed with ordinary steel scrap its value is reduced to the valuerof the ordi nary scrap. In the same fashion, ordinary steel scrap, clean and free of slags and other contaminants, has a high value for remelting in an open hearth furnace to produce steel ingots. lf, however, this steel scrap is contaminated with adhering ush slags, magnetic tap slags and other metal oxides, the scrap in the resultant mixture,V which is of little use in an open hearth, has a much lower value as blast furnace charge material. Similarly, small particles of metal, roll scale and high iron content tap slags when properly sized, and if low in phosphorous contamination, constitute an excellent iron bearing material for blast furnace use which is superior to the highest grade iron ores. Again, if these iron bearing materials are diluted with flush slag so that the iron content is reduced and the phosphorous contamination becomes unduly high, they are not usable to any extent even asalow grade blast furnace charge. There is thus an important economic need in the steel industryfor a process which can beV used on all types of metalV bearing refuse and debris to recover and separate the various valuable coml ponents in these materials. Such a process, to be of maximum value, should (l) recover all of the valuable components free of undesirable materials and contamination, and (2) should separate and segregate these materials so that each recovered component is suitable for use in a process where its greatest economic value can be realized.-

There is no process or method of recovery available to the steel industry which satisfies either of these'requirements. Y

It has thus been an object of my invention to Vdevise a process which will practically and leconomically satisfy these requirements and which will eliminate the rough, makeshift, wasteful, and superficial approaches thathave heretofore been made in processing steel plant slags and metal bearing debris; Y

Another object has been to develop an economical, etticient, and substantially continuous processing procedure orsystem for the complete' recovery, separation, and segregation of theV value content of steel plant slags and other debris, which can be installed at or near a steel plant cinder yard and operated inra continuous manner Y with a minimum cost of yoperation and maintenance for the apparatus involved, and whichrwill enable direct proof easing of steel plant slags from -the cinder yard after a low phosphorous content magnetic tap slags and iron oxides and reject low iron and high phosphorous content magnetic tap slags and magnetic iron oxides without reducing the particle size of the. majority of the product below a practical limit for direct blast furnace use;

A further object of my invention has been to take a process mixture of materials of many characteristics, sizes and nature, and while moving them as a stream, to progressively and selectively sort them out in such a manner that a substantially complete recovery of the metal or metal-bearing content may be effected;

These and other objects of my invention will appear to those skilled in the art from the layout drawings, illustrated apparatus, and the description thereof;

Figures la, 1b, and lc aresomewhat diagrammatic broken plan views which, when taken together, illustrate a layout or an arrangement of facilities for a complete process or system to be constructed and employed in accordance with my invention;

Figure la represents the preliminary or pre-processing portion of the illustrated embodiment of a processing system employed in accordance with my invention; Figure lbrepresents the intermediate portion of metal cleaning and separation, and Figure lc represents the final portion of the same system wherein magnetic separation, refining and concentration is elected. Y

It will be noted that Figure la is to be placed adjacent to Figure 1b along line X-X and that Figure 1b is, in turn, to be placed adjacent to Figure 1c along line XX-XX to provide Vthe complete, continuous system.

Figure 2 is a side section in elevation, somewhat diagrammatically illustrating a dump truck discharging slag materials for processing upon a roller type screening device'which, in turn, is discharging oversize materials upon a steel apron-type conveyor, with the undersize materials falling through the roller screen into a storage bin or hopper; also shown in dotted outline immediately above the roller screen is a clamshell bucket which may be employed either with a crawler-mounted boom crane of conventional Vdesign or with an electric, overhead traveling crane on a runway; either the truck,the bucketfor both provide for charging materials upon the roller screen; this view is taken along line II-II of Figure la (see the lower left hand corner);

Figure 3 is a side section in elevati/ori showing the lower portion of the hopper of Figure 2, together with an electric vibrating feeder to discharge material outV of the hopper upon a belt type conveyor; this view is taken along line III-III of station A of Figure la;

Figure 4 is a sidersection in elevation showing a rotary crusheror impactor constructedrand employed in Vaccorde i ance with my invention, with oversize slag material from Figure 6A is anv enlargednplan View; of@l this r,c ller l 11 Screen;

Figure 6B isa somewhat fragmentalsideview in ele-v vation taken along the. line o fFigu're 6A,-

Figure 7 is a V somewhatdiagrammaticsidej section, in;

elevation of` a magnetic pulley with conveyorbelt to sep? arate magnetic andr--non-magnetic cleansmetal, and to discharge the separated metals upon. receivingl belt; conveyors; this view is taken yalong the line ofstaf, tion F of Figure 1b;

lFigure 8 is a side view in elevation of a self-cleaning, cross-belt, rectangular magnet employed in accordance with my invention, and showing Vpick-up andy discharge of magnetic materials; this viewris taken along lineVIIIr- VIII of station M` of Figure lc but discharge chute 83 of Figure 8 has been omitted in Figure lcg..

Figure 9 isa sidevew in elevation, partially` sectioned, showing the removal of magnetics by thercross-belt rectangular magnet of Figure 8 and by a magnetic pulley,

with magnetic materials from both beingV corribinedwand`A discharged upon a belt conveyor; non-magnetc residue is also` shown being discharged from the belt conveyor;

upon a vibrating screen, with undersize nonfmagnetics.

passing through the screen upon a conveyor and oversize.v material going across the'screen into a roll-typecrusher and then to a belt'conveyor; this-view is. taken along-line IX-IX of stations M, N and O of Figure 1c;

Figure 10 is a side sectional View in elevation offabelt conveyor discharging magnetic materials upon afvibrating screen, with undersze materials passing through the screen` upon. a beltY conveyor, andfoversizel magnetic materials going across 'the screen and into amagnetic separator; also shown is productdischarge at the far right` out of the separator onto a belt conveyonwithY the rejects from the'sepa-rator chuted into a roll-typecrusher, and, then onto a lbelt conveyor; this view. is taken along line X-X of stations P and Q of Figure lc;

Figure 1ll isa somewhat larger side sectional view of a magnetic separator, showing magnetic lines being fed into therseparator, and the productat the far right and rejected magnetic fines being discharged lupon belt con veyors; this view istaken along line XI-XI of station T ofrFigure 1c; Y

Figure l2 is a somewhat diagrammatic broken plan view which, when placed along line Z-Z of Figure lb and as combined'with Figure 1a, illustrates another complete, continuousrsystem which employs principles andV facilities of myy invention to meet an steel plant requirements;

1 Figure l3,is a somewhat diagrammatic plan view illustrating a complete, continuous system employing principles and facilities of my invention in afui'ther. coopera-V tive functional relationship toV meet another exemplary` set of plant requirements as to product size, nature and content.

exemplary set` of General process considerations and procedures Practically all steelplants, in the4 normal course, of sorting and loading out their wastel steel producing slags and other metal bearing debris, retrieyethe,large,` obyious scrap thusv recovered, is generallytaboye v12 inchesin size, and includes steel-skulls and,buttt'gnsf lsomeof which v are as largeVv aseight to,y ten feetv inV diameterl andj weigh manythousands of pounds.I This scrapisv noimally ytransferred to a skull cracker or ballV d rop'laudisI cleaned by, ball droppingfand then cutV asrequired into smaller for recharging. into,.the. furnaces. Intge'neral myA processv contemplates the processingv ofsteel prod ucingslags and debris after the larger pieces of Scrap metal (over l2 A ginches) are recovered by, thispreliminary.- sorting-,out ac- Ition in theste'el plant cinder yards,`

The primary` problem in processingthe residual slag materials-at this stage, is thatof releasing',` cleaning, and

separatingthe, metalfcontent of ,theu mixture (both mag-v, eticfand non-magnetic) from, the various s la'gs and other Theflarger piecesA of metal. (above ,1 inch in size) arevery accept'able,foropenhearth,v

contaminating materials.

orfelectric furnace use while the smaller particles of metal (because of size),are moreacceptable'for'blast furnace.

a use. v

The sl-ags and other materialsin` this mixture vary in piece size. from aPpr0X1'mately24, inches down to clust, and will contain rough, irregular piecestof metal from l2 inches mesh size downY to less lthan 1/100` of Van inch meshl size. The metalicontent, as previously mentioned, is generally not free but is rather embedded in a matrix of tough, abrasive, nommagnetic slag orf other foreign material. In addition, it should Ybey noted that ,both magnetic. and non-magnetic slags are present in the mixture.

A secondary problem in completelyv processing this material is thatof selectively recoveringA cleaning, and concentrating those portions` of the maghetictslags and magnetic oxides present in the mixture Whichl have discovered haveV a high enough iron content and a low enough-t 355 phosphorousV content to warrant their re-use. in a blast furnace for iron production.V Desirably, a maximum amount of these magnetic slags, when recovered, should be of such size (above As of an inch) that direct refuse in a blast furnace can be effected Without` the necessity of agglomerating procedures. Y A

Reference to Figures la, 1b andy lcV vyilltindicate that my system or procedure is dividedinto three principal parts. This division is based upon practical considera# tions discovered in developingV my invention, and as applied to the size and nature of the material being handled and processed. In what I designate as a pre-processing part of the procedure (see Figure la), I, in elect, pr vide a process burden consisting of slags, metals,V etc., all of which has ybeen broken down to an indicated minus l2 inch gridv or screen mesh size, ready for an important second part of my procedure. v Y

In the second part (see Figure lb), `the metal content of a size suitable for direct charging into openhearth and electric furnaces is released, cleaned, and separated v rscreening devices are used at earch stage to bypass the-V smaller size material. of a size range suited each impactor will be fed at a particular station and thus avoid useless wear of the impacting means. In addif, ltion, this by-pass arrangement avoids excessive size reduction of magnetics which are to bey recovered at a subsequent stage of the process. Y

The cleaning and separating of the metall content-of the lburden is eiected by a new and improved'type of This is done so that only r'nateriall apparatus, in the nature of rotaryimpact Crushers, degvisedtand constructed inV accordance with my invention,` and effectively usedY with roller screens and electric vi-, brating screens for separatingmetal content'rdownto 1 inch mesh, size. The metals themselves,beingmalleable,

pieces and desirable magneticsare,v

toy the operatingV characteristicsV of Y tions.

In the third and final part of my procedure or system (see Figure 1c), the burden or material of an indicated minus l inch size range is effectively separated into magnetic and non-magnetic portions and the separate portions successively and progressively processed down to substantially its full extent for recovery of the value content of the burden. v

Electrically vibrated screens are used to separate the magnetic materials into specific size classifications to enable the purification and reningprocedures which follow. away and segregating-out the magnetic metal and desirable magnetic slag content in combination with magnetic selectors or separators. The procedures employed in this part of my process provide clean metal particles as welly Ymagnetic slag material in an indicated to minus' 1 inch which is shown delivered to collecting area (5) for direct utilization in a blast furnace, for example. Smaller metal and desirable magnetics, in a size range from minus l/ of an inch to dust, are shown delivered to a collecting areaA (6) from which point they may be delivered to a sintering or agglomerating unit for more advantageous employment in, for example, a blast furnace.

as a high quality size range of 1/5 On the other hand, non-magnetic slag material underl minus of an Vinch mesh size together with rejected magnetic material under 1A; of an inch mesh size, is delivered to collecting area y(4) for such use as may be advisable. As a result, my system effects a substantially complete recovery, segregation, and separating out of the value content of the original process burden, and does it automatically by apparatus in such combination that eicient and effective operations are accomplished throughout, continuously. It is done in such a manner andv by apparatus that has a low upkeep the nature and utilization of each piece of apparatus, as well as its location is such that the most etective and economical recovery of the value content is accomplished for most eicient product utilization, with a minimum of wear and tear on the apparatus. In general, the apparatus is all employed in a fully coordinated and cooperative manner of functioning in accordance with my invention.

In detail,`my procedure, slag pieces in the pre-process area of Figure 1a, and thereafter involves a continuous line type of. operation, as illustrated in Figures la, lb, and lc, wherein a process mixture of a maximum size content of approximately l2 inches, which I have determined is practical for handling,

onV present day rubber conveyor belts, is continuouslyA moved, While it is subjected to progressive station opera-Y The station operations importantly include an,

impact crushing of the more or less Afriable slag materials to release valuable metals and metal oxides and a simultaneous impactcleaning Yof larger metal pieces to free them from slag contamination. Apparatus, such as represented by Figures 4 and 5 of the drawings, is especially designed and constructed to meet the peculiar needs of my concept in this connection. Y

Those approximate rotor speeds which have beenA found to be effective for each of the various size ranges of material being processed are shown on'Figures la and lb in terms of feet per minute speed at the impact blade tip, and for a particular diameter rotor, in terms of revov lutions per minute. v

vIt is highly important to free the magnetic metals and magnetic oxide materials lfrom each other and from the binding material or materials, so that a full and maximum recovery may be eected. The handling of 'the process materials within the impacting apparatus, as well as the construction of such apparatus, has to be such that theV apparatus willv have va good period of useful life without Roll crushers Vare used in releasing 'or breaking cost, even underv severe conditions and heavy utilization. In other words,

consists of breaking oversize'Y breakdowns and costly repairs. These and other factors of materials being fed a proper speed of rotor or impellerY means, and a proper size of opening or throat through which the materials en ter and are discharged. The operation must be progressiveand selective in order to obtain a substantially full and economic recovery of clean, uncontaminated'metal.

The freed metal pieces Ywhich are essentially nonbreakable or non-friable from the Vstandpoint of my apparatus are, in accordance with my invention, recovered in progressively smallerl size range stages on the basis of their relatively larger sizes or size range with respect to selectively broken-up portions of the process material, and after all of the non-metal materialV has been broken-up intoV a size -range below that of the selected size range of free metal that is to be taken off or selectively removed at a particular stage or station. It may be noted that the volume of the burden'is substantially the same throughout the processing except for the clean metal removed, but the size range of the burden becomes progressively smaller.

The metal content which is selectively recovered along my continuous processing line is shown divided into three size ranges that progressively decrease in size from about a 6 to l2 inch size range, to a 3 to 6 inch size range, and down to a minimum size range of about l to 3- inches, all of which are separated` from the process mixture by screen type separating means. After separation of the metal from the process mixtures, the various size ranges are combined as shown and the recovered clean metal is separated intopmagnetic and non-magnetic components by use of a magnetic pulley as shown in Figure 7.

magnetic stainless steels.

metals recovered at this stage after separation are designated as to their point Vof re-use.

At this stage of the processing, impacting and screen separation arediscontinued and the next stage of theY processing namely; V magnetic separation, reiining, andr concentration of the smaller metal particles, magneticV slags and oxides begins; since,`,(l) the maximum piece size of material in the process burden hasbeen reducedA to a size from which magnetic material may be effectively separated by magnetic dmeans, (2) little or no ,nonmagnetic scrap occurs below this size range which neces-` sitates this type of separation, (3)'there is no further need to segregate magnetic metals, magnetic slags, and mag-A netic oxides below this size range, since all of the metal* bearing material recovered, below l inch in size, is best suited for re-use in the blast furnace, yand '(4) in `this size range and particularly, after removal of larger noncrushable magnetic metals by magnetic means, roll crushers are suitable and'more economical than impact breaking for any further size reduction thatis desired to free entrapped, recoverable materials.

. Throughout this disclosure, when I speak of a size or size range, I have reference` to a particular shape and size of the pieces'or particles which will-pass through a specified screen mesh, guide or roll pass size or opening that has equal cross-dimensions (perpendicular toeach other). Thus, am not actually referring directly to theE size of the shape, lpiece or particle,.but indirectly to its size from the standpoint of the mesh or opening through` which it will pass. This designation is believed to be the most accurate one, vsince the pieces, particles or shapes, areV not essentially uniform from the standpoint of their configuration and may be in the nature of slivers and other odd shapes. Y

At this stage of thepr'ocessing, at the left side of Figure 1c; since;` all oft-:the components of the process mixture under l inchV maximum: piece size, highintensity bedded in relatively large pieces (3/1-` to-l inch) of non-z magnetic slagor other non-magnetic-material which doA nottrespond totthe magnetic fields. The high intensity magnetic iields are shown applied by two separate devices fromtwo directions while.4 thev burden is moving on a rubber conveyorv bel?, With a preferredburden depth` off approximately 1 inch. The,burdenidepthis controlled by the.width. of belt'employed andthe speed of travel of thev belt. The iirstmagnetic device: shown (Figure 8) is a. self-cleaning rectangular electro-magnet suspended approximately 3v to 4 inches abovel the conveyor. belt. Thisdevice removes most of Ythella-rger-` magnetic material and the smaller magnetic material inthe upperportion of the process burden.

rIhesecond device shown (Figure-9) is ahighdintensity electromagnetic ot' the magnetic material as the processA burden isffreelyv discharged across the face of the magnetic drivepulley.` The` crude magnetic materials removed-by.` both offthese devices. are shown discharged and combinedona separateA rubber belt conveyor 3.4'. The non-magnetic portionrof the, process burden. isfshown discharged onto a 3/ 81 inchA mesh` electric vibrating screen O fromV which; material under 1%; of an inch (which is essentially free of any;

recoverable metal content) is conveyor 33b for disposal.

b urdenover 3/s of an inch, is shown asV fed into aA roll crasht-:rl 160 with the .rolls setto; producev minus 3A; of an inch product whichreleases anys-mallrparticles, of reemagnetic metalv from the larger. pieces, of non-magnetilc: material. 'I`hematerial then-shown asreturned to the .main prgcess conveyorf27c transferred on to; another the, intensity magnetic elds previously described.

Thev crude magnetics. whichwere separated' from the non-magnetic process burdenare shownV separated into three separate s1ze ranges by, vibrating screens P and R namely; tofl-- inch, l/s, to of an inch, and minus 1/e' of an inch. Each size range is separately fed, into a magneuc. separaron( such as shown inl Figure,l ll. This type ofseparator consistsof a self-cleaning electromagnet Qtwith alternate northA and south poles suspended above a.y non-magnetic conveyor feed belt 27ft By varyingthe DC. current; inputtof the electromagnet by means of a.

D.C. rheostat and adjusting thegdistanceof. the magnet andi top. conveyor beltl from theY process material, it is possible in this. separator, when, the feed materialinputis within alimited size range, to selectivelyseparate relatively pure clean metal particles and highiron-low phosf.

phorous content magnetic slags and magneticoxides, on

the one hand, from relatively'impure, slag-contaminated.

metal particles rejectedin the larger size ranges aref freed? from: adheringislag and are subsequently. vrecovered by re-A pulley 85 whichv operatesl as the-drive pulley of the conveyor 'belt 27e and removesthe4 balancev The znon-magnetic: process.

from the roll Crusher is;

, 4()V by conveyors 35, S'tagandV 35brto'be subjected again to` inclined position toreceive the burden^(a) cycling withoutv loss of metal or reductionof metal-par-V ticle size. In similar fashion and simultaneously, the

aratorsf as product. The mediu'nrand lowerironcontent slags and,` oxides. (fandlhigher phosphorous content) .offplesser` magnetic attractioniwill be rejected. By crushing these/rejected magnetic slags and oxidesin the larger size., ranges, the larger pieces are broken into smaller pleces:

which I have discovered will vary greatly in their iron:

and phosphorous content. By recycling this Vcrushed matefl` rial, those pieces with a high iron and low phosphorous.; content will be subsequently recovered in lthe smaller sized products; Although there is a size reduction of 'Y the, magnetic slags which occurs in this procedure, the crushingisrdeliberately minimized and conducted by steps, asl shown 0% pass roll crusher 87 atistation Q and Va" passroll Crusher at station` S), in order to avoid unnecessarysize reduction.; yBecause ofpractical considerar`r tionsv-relating-to crushing costs and diminishing product V value and; yield; particle l size reduction ofrejects belowY 1/s of, an'inehis` not` shown in the processingof crude metallies! It should be noted that use of themagnetic separator, intitself; cannteconomieally accomplish the desired@ resultsin processing and refining crude metallics but v must- Il'ieused-in a combinationcrushing and recycling arrange--l mentes show-n.- Flhusr-by the usey of equipment and proc essing shown in Figures lc, 8,-9,110-and ll, substantial;V

Q and S are shown combinedl into an singl-ls to linch;

productV onconveyor 36' forvdirect blast furnace use As; shown in Figure 1c, magnetics-below 1/8 'ofganinchrin size are concentrated in a third magnetic separator at station` T, Figure 11,*andthe product conveyed by conveyor- 37 to aseparate area. This product shouldpreferably beagglomerated in a sinter plant- (alongwith due dust and; oretnes) before attemptingto use'it in a blast furnaceilr order to avoid excessive dust loss in the,` furnace'.y

Process line apparatus By way of. example, and particularly referring to Figurer 1a,- and additionally .toFigure 2, I have shown aninitial station A which represents a sector or areavatwhichv proc-A` ess material is delivered. A clam shell bucket;9 handled. bya crawler mounted mobile lift crane or `an electric, overhead traveling'crane (handling device not shown) or a. dump truck 10 may, as shown in Figure 2, be employed to deliver the process material or burden (a) uponA a roller screen table or bed 12 (see also Figures; 6 and 6A),

The screening` cross-positioned table 12V from-an upper, inclined chuteportion 1K1. and to disc-barge oversize slagor debris of plus l2 inches-mesh size, as shownj'along av lower, front chute lupon a side-positioned, longitudinal, continuously-forwardly moving apron conveyor 15 n that may bedriven by' a suitable motor (not shown). Material or burden of minus l2 inches-in size dropsdownwardly through the grid openings or passes of the table; 12, into a downwardly-converging chute 14. i

Process burden or material of a larger size group,y shown as plus l2 inches mesh size consisting of friable; pieces of slag that has lpassed over the table of station Y is, in eiect, recycled back to thehopper 1'4 to join the undersize material along a longitudinal, continuouslymoving, side-positioned, returnfbelt conveyor-28 andgchute 28a, after (as shown in Figure la) it has been impactedl or broken-up at atransverse-station Bv by-rotaryimpacvtor-z Crusher 40. j

Referring particularly to Ifligurey 3' oftheL drayrirrglfithe burden or process material from station A that hans is shown in an:

screen yapparatus 12 (shown passed 'through the roller size) and the broken material as minus l2 inches mesh In this connection, see the commercial Jetfrey-Traylor feeders, as set forth in the 1951 catalog`830 of the Jeffrey Manufacturing Company of Columbus, Ohio. The apparatus 26 thus serves under the hopper as a forward feeder to discharge and distribute the process burden substantially evenly upon the-main Vbelt conveyor 27. The vibrating unit 26a is shown resiliently the front portion of the feeder apparatus suspended from an overhead support member 26e by a pair of adjustable resilient hangers 26d.

I have illustrated in Figures electro-magnetic vibrating unit 26a.

4 and` 4A, a typical impactor apparatus constructed in accordance with my in-r vention. As shown in Figure 4, the larger size burden carried by the apron conveyor 15 is discharged therefrom into a forwardly-downwardly-inclined, upper feedrchute 41 of the first rotary impactor-crusher 40 (see also Fig-V ure 1a) at station-B.

'In Figure 4, the chute 41 is shown boltedto a metal plate housing 42. The housing 42 has suitable handling tabs 42a and 42h (see also Figure 4A), and along the reaches of its front impact end wall is provided with a shock-absorbing liner or intermediate layer 43, such as of wood. The housingV 42 is lined along its inner impact end wall by a series of abutting, side-stacked, steel billets 44 that are held in position by vertical end grooves provided along the opposite side liner plates 44a. The housing is lined along its opposite sides and top by heavy metal plates 44a, such as of abrasion-resistant steel, that are suitably secured in position to outer members of the housing, such as by stud bolts welded to the liner supported on a stand 26b andV 12 Energy ofv impact is transmitted to the material by the rotary wheel or impactor means 50.y As shown in Figure- 4, the Vperipheral surface" of the impactor 50 is protected by an abrasion-resistant steel facing 51 of suitablethickness. Radially-positioned mounting slots 50a vproject outwardly toward the cylindrical surface or'face of the impact rotor 50 and correspond in number and Y spacing to the desired spacing and number of impactor plates and projecting through suitably positioned holes in the housing. Y

The feed end of the apparatus 40 has Va metal, outwardly-projecting, angle-shaped, back end box wall that carries a removable end cover 46 that is held in position thereon by suitable threaded bolts 46a. A downwardly-inclined guide plate member 48 has an upper pair of projecting, back-mounting lugs or ear's 48a that are secured pivotally to opposite sides of the box 45 by pivot pins 48h.' Bars 47 fastened to opposite sides of the box are-provided with a series of holes to alternately receive bolt and cotter pin assemblies that are termed adjustment side bolts 48d that are fastened through a pair of backwardly-mounted'lugs 48C to opposite sides of thel box. It will be noted that the pivot is at the upper end ofthe guide plate member 48 and that the adjustment bjolts 48d are carried adjacent its lower end, so that the inclined positioning `of the guide member 48 may be varied between4 the dot and dash positions (b) Yand (c) of Figure 4. The adjustable guide member 48 is shown provided with an abrasion resistant steel plate wear surface 49 'bolted or otherwise secured onto its top face. The cover 46 may be removed, so that adjustment of the guidevplate 48 may be easily accomplished by moving the adjustment side bolts Y43d to suitable, oppositelyaligned notchesor holes in the side bars `47.

When the guide member 48 is in its uppermost position (b), it delivers -the burden more Aforwardly ofthe impact rotor or impeller means or wheel 50 (in the direction of its shown counterclockwise rotation). Conversely, when the guide member Y48 is in its lowermost or greatest inclined position (c), it delivers the burden more towards the vback of the rotary impactor 50. For'larger and heavier materials, the adjustment is more toward the latter position and for smaller size materials, it is advanced or pivoted to an up or more forward posi-l blades or elements 52, which are constructed Yof an alloyV steel such as a molybdenum-silicon alloy. For rotor balance, the blades 52 are equally spaced peripherally around the rotor and are shown secured' in place by inset pins and wedges or key elements 53. The key elements 53 are carried beneath the facing S1instepped, slotted portions 50b, so as to protect them'from the burden during the rotation of the wheel or rotor 50.

As shown particularly in-Figure 4, the outer metal housing of the impactor 40 is bolted together. p 'Ifhe top of the housing and lining'44a is readily removable by unbolting and lifting on the lugs 42a fo'r'maintenance access to the interior of the machine. The burden after impacting falls downwardly through'a lower open end portion of the metal enclosure 42, onto a downwardlyconverging discharge chute 54, and upon a suitable conveyor which, in the case of station B, is the return belt conveyor 28.

As shown particularly in Figure 4, the rotary impactor wheel or rotor 50 is secured on a drive shaft 55 by key means 56 to rotate therewith. The shaft 55 extends at its opposite ends through opposite, removable, end-slotted side plates of the housing 42, and isV rotatably supported with respect thereto by side bearings 57. The opposite end portions 55aY and 55b (Figure 4A) extendpthrough bearings 57 which are mounted on spacer blocks 57a, and the end shaft 55a carries a V-belt drive wheel 58 that is keyed or secured to theV shaftlto thus drive the rotor 50. A motor-driven side-positioned beltY (not shown) is adapted to engage the wheel 58 and drive it at a suitable speed. It may be noted that the impactor-crusher or rotor 50, its shaft 55a, and its,r bearings 57 may be removed as a unit by removing front end plate 42' (see Figure 4), removing'bearing stand bolts 57b (see Figure 4A), spacer blocks 57a, dropping the unit down on side rails 57e, and rolling the rotor assembly out through the end of housing 42.

Figure 5 is a fragmental illustration of belt conveyor 29 at station D (see Figure 1b) feeding an impactor 40a of the same type illustrated in Figure 4, and is taken along the line V-V of Figuredb. 'I'his type of belt conveyor feeding to theimpactor 40a is also employed in connection with the impacting operations-conducted at subsequent stations H and K of Figure 1b by impactors- 40h and 40C respectively.Y Y Y Y Screened burden or process material of a proper size range, as shown in :Figure la, of minus l2 inch size, which includesV slag Vand metal, is shown continuouslyV advancing forwardly from station A on belt conveyor 27 to station C of VFigure 1b. Station C consists of a rollerAV screen 12a of a type, such as shown in Figures 6 and 6A of the drawings, having a suitable size of grid or pass opening. In Figure lb, the passes of screen`12a at station C are shown as 6 inch mesh size. Y. Q l

At station C, the larger size portion of the burden (the oversize as indicated of 6 to minus 12 inches mesh size) is discharged from achute similar to chute 13 (see FigureA 6) onto a continuously-moving conveyor 29 (see Figure lb) for impacting at station D. The smaller size portion (the throughs as indicated of minus 6inch mesh size) passes Vthrough the screen 12a and is discharged by a chute similar to chute 14 (see Figure 6) onto the lon- Y gitudinal, forwardly-moving belt conveyor 27a that cartion.; In any position it provides at least a substantially v tangential delivery of theV materials to and from the peripheral surface of the impactorY means 50.A

Y V'as ries it to roller screening station G. Material from the impactor 40a at station D, shown as consisting of 6 to minus 12 inch clean metal (which has been cleaned but not broken) andv minus 6 inch slag (which hasibeen screen J at station I.

13 broken by impacting) is returned along a transverse, continuously-moving, return belt` conveyor 29a and fed onto-` the screen bed ofV a roiler screen 12b at station E.

This screening at station E discharges, as oversize, clean metal (as indicated) of about 6 to minus 12 inches mesh size along a forward chute similar to chute 13 (see Figure 6), upon a transverse, continuously-forwardly moving belt conveyor 29b, and from it onto a longitudinal, continuously-moving, side-positioned, clean-metalcarrying belt conveyor 32. Thus, at this point of the process, the rst separating-out of the clean metal content of the burden is eiected by vscreen separating it as oversizefrom the remainder of the burden which includes smaller size slag and smaller size metal.

At station E, the smaller size portion of the burden (the throughs shown as of minus 6 inches mesh size) is discharged by a chute similar to chute 14 (see Figure 6) of its roller screen apparatus 12b upon the forwardlymoving conveyor belt 27a to combine with the throughs of the same maximum size from station C. The belt conveyor 27a advances the now-combined smaller size burden to another roller screen station G having a screen 12e of smaller screen size than the screens 12a and 12b at stations C and E respectively. At station G, the smaller size portion (the throughs indicated in Figure 1b as minus 3 inch slags and metals) is fed from station G onto a longitudinal, continuously forwardly-moving belt conveyor 27h which deposits the material onto a The larger size portion of the burden (shown the oversize as 3 inch to minus 6 inches mesh size) of screen 12e at station G is delivered onto a side-positioned, continuously-moving belt conveyor 30 which carries it to an impactor 40b at station H. The impacted burden from station H (shown as consisting of 3 `inch to minus 6 inches mesh clean metal and minus 3 inch mesh size slag) is returned on the side-positioned transverse, continuously-moving, belt conveyor 30a to a 3, mesh roller screen 12d at station I,

At station I, the larger size portion of the burden (the oversize from screen 12d), which is shown as nowconsisting of 3 to minus 6 inches mesh clean metal, is discharged onto a transverse, continuously-forwardlymoving belt conveyor 30]), and then onto the longitudinal, clean-metal-carrying conveyor 32. As indicated, the roller screens12c and 12d at stations G and I are the same size. Also, as shown, 3 inch to minus 6 inches mesh size clean metal is screen-separated from the other portion of the burden (shown as consisting of minus 3 inches mesh size slags and metals). The smaller size (the minus 3" mesh size throughs of screens 12a` and 12d) burdens from stations G and I are combined on conveyor 27b and advanced forwardly to the vibrating screenl at station I.

As shown particularly in Figures 6 and 6A, a roller screen apparatus is provided in accordance with the principles of my invention that, in eiiect, is a modied type of rotating grizzly that is side-balanced as to its driving means. The. roller screen apparatus 12--12d as used at stations A, C, E, G, and I, comprises a suitable structural housing 20 that is provided with an upright support frame structure 24 and cross-connecting support members 23. The shafts of a series of cross-rollers 22, which dene theA inclined roll table, pass through dust sealsA 20a into bearings 21 within the housing structure 20. As shown, the rollers 22 provide a series of passes along the length of the bed through which the undersize portions of the material may pass. The shafts of two of the rollers 22 are driven through a pair of V-belt drive wheels or pulleys and 15a, by a set of V-belts 16 from a motor-driven V-belt pulley or wheel 15b (see also Figure 6B). The drive wheels 15 and 15a are of larger diameter than the motor-driven wheel 15b to provide a speed reduction effect as to the actuation of vthe rollers.

It will be noted that alternate rollers 2 2 are drivenM from oneside of the apparatus by the .wheel 15, through, extended drive shaft 17, sprocket wheelsA 18, and sprocketA chains 19. Other rolls 22 are driven by the wheel 15a and extended drive shaft 17a along the opposite side of the apparatus by sprocket wheels 18a and sprocket chains 19a (see particularly Figure 6A). Starting at the top or entering roll of the screen apparatus, each succeeding roll 22-is driven at a progressively faster speed than the preceding roll by the use of Vprogressively smaller drive sprockets, so that the oversize material will feed smoothly acrossthe roll table and will not clog or jamthe grids or roll passes. As previously noted, the under size portions of the burden pass through the roll pass. openings or mesh of the roll table.

As shown on Figures 1b and 1c, I prefer to use electric vibrating screens I', L', O', P' and R' at stations I, L, O, P, and R respectively Where the screen mesh size to be usedis 1 inch or smaller. I have somewhat diagrammatically illustrated an electric vibrating screen P in the left portion of Figure l()y of the drawings which is employed at station P. In Figure 9 of the drawings, I have shown screen O which is employed at station O. Each of the screens O' and P' is 5% mesh.

The vibrating screen apparatus as shown in Figure 10'has a supporting frame structure 60, resilient support rod assembly or structure 61, a downwardly-declining upper feed or input plate 62, a downwardly-declining vibrating screen table or screen feed trough member 63, on which is mounted a wire screen 63a of suitable mesh size, an under-delivery outlet chute 64- for smaller size material, an end-delivery, outwardly-declining, bottom guide or outlet plate 65 for larger size material, and an electrically-'activated magnetic vibrator unit 66. Screensv of this type are available commercially, such a unit being manufactured by the Jeirey Manufacturing Company of Columbus, Ghio. The table 63 is pivotally suspended near its upper end by the adjustable side rod structure 61. The rod 61a passes through a cross frame member 61b. A resilient member 61e is interposed between the crossA frame member and a nut 61d secured to the rod. The vibrator unit 66 is secured to the sides of the screen table adjacent its lower end and is pivotally suspended from the. frame structure 69 by a pair ofl pivotally-mounted, side-positoned hangers 61C. Each hanger 61C is provided with a turn-buckle to adjust its length.

ReferringV again to Figure lb, the smaller size burden of'minusr 3 inch slag and metal which is carried forwardly by belt conveyor 27b, is delivered to the vibrating screen J at station J at which the smaller size portion of the burden (as indicated, of minus 1 inch mesh size) passes through the screen and onto the longitudinal, forwardly-advancing, continuous belt conveyor 27e. The larger size portion of the burden (the overs, as indicated, of 1 inch to minus 3 inch material) containing both slag and metal passes across the vibrating screen J of station J and discharges onto a transverse, side-positioned, continuous belt conveyor 31. The conveyor 31 delivers its burden to a rotary impactor` Crusher unitV 40e at station K from which it is returned on a transverse, side-positioned, continuous belt conveyor 31a to a vibrating screen L at station L. At station L, the clean metals, as represented by the larger size portion of the burden (shown as of l inch to minus 3 inch mesh size) pass across the screen onto a transverse, continuouslyforwardly moving, belt conveyor 31h, and then to the main longitudinal, clean metal-carrying, belt conveyor 32. The smaller size portion of the burden at station L (the throughs from screen L shown as minus 1 inch mesh size) is discharged upon the forward conveyor 27C and thus, combines with the same smaller size burden from station J.

Referring particularly to Figures lb and 7, clean metal of a size range of 1 to minus l2 inches mesh size thatl has been delivered from stations E, I, and L, is combined on the clean metal-carryingconveyor 32 and ca rrieclby;y

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