| Show present trend of 10 milling flotation flow sheets and the classification of dejoia flotation ore ajo feed by AE A aa W fahrenwald the dill art of 10 flotation suil has developed rapidly numerous technical staffs pim and individual investigators have by their combined p efforts p developed IDAD pado practicable methods so of concentrating conof cent rating ores which ten 1134 or 10 even five years S ago were considered alo complex pim and impossible so of commercial treatment also the dill work SO of those who OLIM have abeen edua engaged pdt in ill pure band research at on the dill fundamentals so of flotation has helped greatly to ol expedite the dili 2 general lualua development so of the dill process however ill in spite so of the dill highly successful practical operation so of the flotation process results diu are obtained and things happen that imp we dak diu are unable to ol explain completely although if much 0 11 1 is s known about the dill theory so of the dill process the rapid stride ill in flotation concentration it 41 ST is noteworthy to ol point out ino si is due gnp to ol the dill freer exchange so of facts and up data by the dill staffs so of the dill larger mining companies cuoz pin and the dill led patent luI controlling corporations and q by A investigators ill in general 1113 generally speaking one DUO may visit any mining plant lurid and pu by presentation so of proper credentials be shown ilu all that is going on or ao that si is being done quite naturally su as the dill supply so of relatively high grade O PUO and PU ED easily als treatable solo ores st is worked out ino the dill necessity for q handling the leaner and more complex ones confronts us sij the ajl difficulty SO of treating 4 zil the so os called complex ores that imp I 1 is S I 1 ores 0 I 1 sz consisting suo Isi oil of jo a number so of metallic sulphides sulp hides with IMM each other and with the dill worthless mineral ll has I 1 until quite dip recently been a stumbling block alq iab 1 1 mining operations skilled palls i researchers pilu and experimenters SI have brought to 01 bear on the dill problem scientific methods 10 i attack anjil the microscope for example xz SULI has been ug of 10 value in helping us to 01 get a 11 true 11 D mental I picture of 10 the problem present flotation practice there seems to 01 be a tendency on the dili part laud so of ore ojo dressers fo 01 lean auz too heavily ui in either one duo direction or ao the dill llo other It l ako how f ver those advocating all flotation plants predominate 01 L 1 I 1 here are many ore dressing 2 plants ill in the dill country which 11 sn use y X IOU flotation u 03 concentration U Z D alil u pilu and many combination grav y pilu and flotation plants diu are rapidly going to 01 lip all flotation ln ill OT a to ol apply ILL an III all flotation treatment lua the dill LID entire ore 1310 must q be ground to ol a suitable fineness I 1 generally div through I 1 qa a 39 o mesh OZ mm s screen lo alaa particles od coarser aarm than 65 59 mesh are oil ot readily td picked up on the dill face of 10 things one is 1 likely aj w assume that quill the dill justification for boj such fine dug grinding is S the dill late DI association so of the dill minerals comprising the dill ore alo ln is that dill there aj st is ou ho economic liberation or jo luli unlock Vo g ot JO the gangue put and ore minerals e above this mesh jj if re dressing redressing engineer U n S bureau of jo mines moscow idaho this si is the dili fact such a u procedure si is not jou only eluo justified but necessary however AZAkOFf 10 plenty so of practice si is to ol be found where careful examination so of the ore ojo sop does not jou show ill this s to ol be the dill case 3 often a u large percentage so of the dill respective gangue ea put and ore dio kuitu minerals si is observed to 01 be completely liberated at sizes so of 14 mesh is I 1168 1 mm PUL and 3 coarser shuo 13 on ito inquiry so of the dill managers their justification folluo is Is and it J ST is a I 1 difficult one duo to oj 1 get 0 40 around that they can I 1 make more profit by the ill 33 excessive 33 DAISS fine grinding V and L p flu all nog flotation boil method it 11 st is claimed that better grade products PUE and higher recoveries M are 3 made this casts a rather heavy reflection on our ano 11 methods SO of gravity concentration which we am diu are or jo have been accustomed to ol use on lio such 11 tuoc coarse Ds sands however some consolation bopulos st is to ol be cil had p ui in the dill vj fact I 1 that little DIMI effort I relatively 1 speaking smi has been made to 0 increase the dill efficiencies of 10 gravity 0 vm methods the highly spectacular flotation q methods have absorbed our ano thoughts pur and gravity methods blaw so of concentration seem to ol be dying slowly without A a 1 llis struggle DIl plants here coq put and there are dropping jigs or 10 I 1 tables c out so of their amill lizs scheme DulD of jo treatment for such a trend ul in considerable justification OH however k D I 1 ore dressing may kew be cited some SO of the dill advantages SO of III an III all flotation plant are a 1 simplicity so of construction suo and operation b q mol low first cost per aad ton so of ore aio to ol be treated juDal pD J be ll handled on a small floor space azudt can c Z large hjul tonnage 01 fine initial crushing and U p if d p complex saab ores require a very IQ mineral must be recovered by flotation why not IOU d part I 1 aa SO of zill the flu all so of it I 1 by the dill same amps process alii this s makes for simplicity c D two minerals SO of the dill same or 10 nearly the dill same Dds specific og gravity methods c and pu 1 high cannot be separated by gravity the dill recoveries and good d grade aati products ic are attainable by with greater juDIA Ia certainty AD aj flu all flotation method flotation st is applied than mill a few years back and it I 1 is S surprising to 01 note the dill observation of jo a I 1 sini als T the al a lare ojill al tonnages ton nages 0 sa handled under 5 alc 1 0 operator lundo jo mold flow sheets st is shown III in the simplest j form 10 UT SO of ill an iju all flotation plant the atil best I flow 1 akol sheet ON no 1 f III in fact this mog flow sheet represents mineral concentrate practice where D say only one duo present day the dill first flotation elou boll va machine I 1 ursul instances adu st is desired in III some 11 middling and a tailing lluu makes so a clean concentrate a feed PIN end of jo the atil returned pa to ol the qa head or IO 10 the dill middling TIPP being would be nilder applicable idt to ol copper it 41 CLU machine JOS for example such SL as assip disseminated type D for so of the dill highly and 10 ores SD flotation in utah 14 arizona v are da q being 15 LI concentrated by concentrate sa s1 is wanted and oj for 1 ores where a new mzx mexico due content zal metal because it I 1 SI is valuable for its sl id precious associated with be silver may precious prec ioup metals gold PIO and or rd am 1 0 11 dag cr rake W cyp 6 d 11 pat I 1 aff rl ar tar t hs at s f y PM P M W paws C fw F w h ac FW A 6 C rk r k ki A two iss v sast m coa foe crusher jaw or gyratory 1 acre screen in ahry j LO I 1 oversize Over veaze aize medium crushers rolls rolis or Sin simona rions dt screen or vibrating A arn opening 1 ma J 2 ta I 1 y TI z arn J I 1 const gr enill ba 0 od L thickener eckener ciot no 1 table sp spigot 01 no 2 7 cont const apigo no a table ie spigot noi E tal 10 adlino flocked 3 C toil unlocked C const naf benl E LOW FOW F OW ahee 4 E s D 0 W a ore feed reagents to io flot AB az allf grinding rg mill coarse sand C afler drag 9 over j I 1 fane dmd 0 overflow over er flow to grind rg W t r ba B R rougher in er flot flat machine or flotation I 1 AW A A W B rougher conca I 1 1 tail rall to wate reagent to fo ap B AB cleaner acleane flo rr iachine madli IES cleaner conca conal conditioner conditioned AB A B T flot m machine hirle filter thickener 6 B cl con A fa froth froh thickener bilter s FLOW SHEE SHEET NS N 3 ore 1 Grind no ill ca classifier i er CD C D hindered lype cype I 1 lra no I 1 overflow arr c kene 1 ap M 2 1 S nwe pi 3 n prof no 3 po afta ay s spigot 4 mill FLoT flotation AriON plant CLOW ahe N 5 coulsting of USI U v cleaners 0 ore middling regiments Rei ments T gri inq mill 11 p flo io i i rougher ana ou he bonc n 0 Q H ing pota ion Ll leaner eaner A L cacao to ore to dump aal isa FLOW ehg NO 6 ore baked adi cortri min L thickener FI bend alne ma ra on fa bonef SHEET various mineral sulphides sulp hides and are segregated from the ore by recovering the sulphides sulp hides in a float concentrate certain other ores are amenable to treatment by this simple flow sheet the number of re treatments of the original rougher concentrate is not limited to one but may be as many as three or four flow sheet no 2 represents a typical all flotation scheme of concentrating a complex ore consisting of two economic minerals A and B and is the one that will be most aten observed in the plants where best work is being done while this may be accepted as the general generah practice there may of course be some modifications or deviations in detail for example each rougher concentrate may undergo two or three cleaning treatments in as many individual machines this is determined by such factors as the nature of the ore and smelter requirements where avilene the ore is complex such matters as 1 the typo type of grinding mill best suited to the particular ore in hand 2 the type of flotation machine 3 the type of classifier to give a best flotation conditions and b greatest grinding 0 mill efficiency 4 the reagents to be used and where they shall be added to the circuit are important details in the successful operation of the plant still another all flotation flow sheet originally proposed by coghill and anderson andersen gives promise of success judging i ig from the work now being done in two of the large concentrators centra tors of the country see flow sheet no 3 this flow sheet has many features to recommend it the scheme has for its object rejection of the bulk say roughly 80 per cent of the ground ore as tailing at an early stage in the milling this is entirely logical particularly on complex ores that have a small percentage of floatable content the economic mineral content of the ore is obtained in in relatively small bulk and a concentrated effort may be made to separate the economic minerals one from the other such a scheme as this has been successfully worked out in two plants this scheme heretofore appealed little t to 0 the majority of flotation engineers the reason being that it was thought that once a mineral particle is oiled it could not be reconditioned and would persist in floating under any subsequent treatment in ores where the percentage of floatable mineral is high this flow sheet is not so attractive and it yet remains to be demonstrated that it is the most logical and economical method in such cases contaminated ores flotation methods the so called contaminated ores should be differentiated from complex ores complex ores are thought of as those ores in which several valuable minerals of different or similar specific gravity are highly disseminated and interlocked with each other and with the gangue minerals contaminated tamina tamin ted aled ores are those that have associated in them colloid forming or organic substances that cause them to behave eni entirely abnormal to flotation therefore a contaminated ore may and generally does call for a flow sheet shed varying somewhat from those shown above there are several proposed methods of treating so called contaminated ores A method which we will term number 1 calls for a flow sheet similar to either no 1 no 2 or no 3 depending upon the number of india individual minerals to be recovered as such method no 1 calls for the use cof suitable chemical reagents which may accomplish the 11 e desired results in either one or two ways a by rendering the colloidal or f foreign orein substances which may be substances in solution harmless to subsequent flotation treatment of the ore and b by peptizing or de flocculating the colloidal co bidal material and washing it out by overflow or decantation there seems to be a large variety of patents covering the removal of colloidal material by and decantation sodium silicate has been found useful in this alm connection another proposed scheme which we will call method number JN umber 2 is is to aerate the pulp which results in surface concentration of the contaminant the contaminant is then removed by surface skimming and the pulp treated as usual method no 2 is is based on the assumption that the contaminant tami nant lowers the surface tension of water organic substances usually do and they may therefore be collected on the surface of bubbles by the process of adsorption the process is conveniently carried out in a machine that gives intense aeration using as efficient a skimming mechanism as possible it is well know that the de slimed part of ground so called contaminated ores is readily amenable to flotation treatment in sliming de the ore chemicals should be used to disperse the slimy or true colloidal material as completely as possible so that it may be thoroughly washed out carrying with it a minimum of fine sands true colloidal portions of ores seldom contain much valuable mineral certainly the surface tension lowering constituents remove removed dby by aeration and skimming would contain no ordinary mineral values flotation the primary method in a large number of the 0 ore redressing dressing re plants of today flotation is is made fiade the primary method with tables occupying a secondary place in the scheme of treatment tables are often used to follow up the flotation machines in some insignificant manner either 1 to act as indicators of the completeness with which flotation is doing its work 2 to recover coarse mineral or middling or 3 to recover a particular mineral that does not respond to flotation and which is is worth saving often flotation concentrate is passed over concentrating tables for the purpose of making higher grade A concentrate and B concentrate generally speaking tables IL used in this manner little more than pay for their operation gravity Concen concentration concentrate trat ion followed by flotation it is true that any ore can be ground to the required fineness and the ore minerals recovered by flotation and mechanically this offers a simple flow sheet there arey are however factors involved in ill the treatment of ores other than recovery and simplicity of flow sheet generally generall y speaking 6 it will be conceded that an ore should be milled by the method that will net the greatest profit to the operator A typical combination gravity and flotation flow sheet is s shown in figure 4 on first glance this flow sheet impresses oil one e as being complicated on simple ores that is ores from which one mineral only is tobe to be concentrated this flow sheet cannot be considered complicated from the point of view of individual units it is but the advantages of it over all flotation schemes where it is applicable area are 1 no skilled operators required 2 no delicate and easily upset physical or chemi cal forces involved in the recovery of often 75 per cent of the metallic content of the ore 3 the bulk of the gangue b minerals are concentrated out for discard in the form of large pieces 4 a large t percentage of the ore minerals are for smelter nelter treatment ill in the form concentrated out ready si of large pieces 5 a saving in flotation royalty 6 the the coarsely granular concentrate convenience of handling b m 7 the consistent good efficiency of a plant and 8 lower power consumption and low grinding costs par ticul arly where the L Z gangue minerals are tough and difficult to grind the operation of a gravity concentrator is a very simple |
