CA1072343A - Process and device for suspension smelting of finely-divided sulfidic and/or oxidic ores or concentrates - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
A process and device for suspension smelting of finely-divided sulfidic and/or oxidic ores or concentrates are dis-closed, wherein a suspension of the finely-divided raw material in an oxygen containing gas is directed downwards as a suspension in a reaction zone formed jointly by the suspension and a melt below it, in order to oxidize and partially melt the raw mater-ial in suspension, whereafter the suspension flow is caused to change its flow direction perpendicularly sidewards so that most of the raw material particles present in the suspension flow impinge against the surface of the accumulated melt in the lower part of the suspension reaction zone, and the remaining suspen-sion flow is directed into a rising-flow zone, and the solids are separated. In order to improve the energy economy of the suspension smelting and to increase the capacity, the tempera-ture of the particles falling downwards in the suspension reac-tion zone is regulated so that the change in the heat content of the particles impinging against the melt covers the heat quantity required by the endothermal reactions occurring in the melt and together with the change in the heat content of the gas replaces the thermal losses of the furnace.

Description

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Process and device ~or cuspen~ioll smelt~ng of finely-di~ided sulfidic and/or oxidic ores or concentxates ~ he present inYention relates to a proce~ a~d device lor the ~uspen~lon smelting of flneLy~divided sulfidic or o~cid~e and sul~idlc ores and ooncentrates.
~ he suspension sraeltirlg o~ sulfidic co-~ce~trate~, baBed on ~innish Pat. 22 694,h~s ~een increasingl;y adopted all over the world. It i~ known to be economical in terms of energy and, wrt~a3 moxe 9 it i~ a smelting process frien~ly to -the enviror~lent. ~his s~-c211ed au~ogenic :1ash sm~ltirlg process iS9 howe~er~ now'~lexe fully ~ togenict i~e., ope7~ating wi.thout e~ctexllal fuel, but large quant:l.ties of fuel? usually oilt must be used at diff'exent.
pointæ of the :Elash smal i;ing f~ ace ~ The flash sm~ltin~ process ~s we~ no~ and has be~ described i~ ~e~rera:L articl~s (e,g.
Jou~nal of Metals, Julle 1958, Petri :13ryk, John Ryselin~ Jorma ~Io~kasalo, 3,~1d Rolf ~Aalmstrôm: "~lash Smelti~g ~opper ~oncer trates" and 'l~h~ ~irst I~ter~la~io3lal ~las~ Smelti~lg Co~ re~ ?.inlavld~
October 23~ 2.7, 1972 .:
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Describ~d briefly, the proce~s i3 as follows. ~ried, finely divided concen~ra-ke plus the circulating flying dust and pos~ible slagging agents and air a~d/or oxygen mixture, preheated ox cold~
are fed downwards into a vertical flash smelting furnace reaction shaft, where -the oxida-tion reactions oGcur ln ~u~pension at a high temperatul~e. Under the effect of the heat of reactlon and the possible additional fuel, most of the reaction pro~ucts smelt (~ith the e~ception of certain slag components). When copper concentrates al~e concerned, the following sum reaction~ can bs thought to occux in the reactlon sha~t:

2 Cu ~eS2 ~ Cu2S ~ 1/2 S2 ~ 2 FeS
CU2S + 1 1/~ 2 --~ CU2 ~ S2 ~eS2 - ~ FeS ~ 1/2 S2 1/2 S2 ~ 2 ~ SO2 ~eS + 1 1/2 2 ~ 'eO + S02

3~eO ~ 1/2 2 - ~ ~e~4 Similar reactions occur in the case of other concentrates.
~he ~tlspension falling from the reaction sha~t arrive~ in the hori~ontal fur~ace part, the so-called ]ower ft~nace or ~ettlex9 ~here there are at lea3~ two but sometimes three different melt layers. ~he lowest one can be a metal -layerp usual~y blister copp~r, with either a ~atte layer or directly a slag layer on top o~ it, ~sually the lowest is a mat-te layer with a slag layer o~ top of ito Most of the melt and solid partioles in suspens~ox ~all directly into the melt ~/hich is below the reaction shaftp at apploxima~ely the ~lag disch~rge temperature 9 and the most finely ai~ided part co~tinue~ along with the ga~e~ ~o the oth~x end of the ~ulnace. On the way~ suspensio~ keep~ falli~g into the lower furnace~ At its ot'ner end the gase~ are dix~cted straight upwards ~long the ri~ing ~ha~t and ~uxther o~ tc the gas trea~
ment device~, the waæte heat ~oiler and the electric filter.
Usu~lly tne aim ~ to per~oxm the smelting as autogenioal-ly as possible, without outside fuel~ ~or this purpo~e~ air is preheated and/or ox~ygen-e~riched i~ t`he reaction shaft.
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~ 2~3 When using convent~onal sulfide concentrates ~hich corltain chalcopyl~ite, perlilall~1it~s, pyrite~ and o~her sulfide~ of i~or.
it ha3 been noted that the oxidation of iron in ~he reac-tion shaft does not result i~ t~le ~orma~ion o~ the de3ired ~eO ~ut the reactions con~i,nue as far a3 ~e304~
~ he higher the grade of matte desi~ed in the smelting, that i8~ the further the conce~trate is oxidi~ed in the reaction shaft at the temperatures in que~tion, the higher the de~ree to which the oxidized iron is in the form of magnetite~ Fe~0~9 in the : lower pal~t of the reaction shaft~ Oxide~ of other metals can also be produced. In any case, an equi~aIent qu~ntity of i~on sulfideg ~eS, or other metal sulfides re~ains uno~idizedO ~he final reactions occur almost solely after the partic].e~ have fallen into the melt in the lower fuxnace 9 and the desired matte and/or metal and slag phase~ are thexeby produced~ ~he ~ollowing reactions are possible:
Ia 3~e34(s) ~ ~eS(2) -~ lO~eO(s) ~ S02~g3 ~ 1300 Ib 3Fe34(1) ~ Fes(a) -~ lO~'eO(s) ~ S02(g) ~X 1300 II 2FeO(~) ~ SiO2(g) ~ 2~eO SiO2(2) ~X~ o ~ ~ 735 kJ
III CU2S(2) ~ ~U2~(2) -j~ 6aU(2) ~ S 2(g) ~Hl300o - + 7~.2k~
IV 3Cu2(2) ~ ~es(2) ~ 6~u(2) ~ ~eO~ S02( ~

: 13~0 ~5 2 (2) (2) ~ ~e(s) ~ C~2S(2) ~-1~00 ~ 11~ kJ
~a~II 3~e3o~ eS(2) ~ 5Si2(s~ -~ 5~2~eO ~ SiO~)~2) + S02(g) ~EI 1300 ~ ~ 766 kJ
Ib~II 3~e30~ Fes(2) + 5S:io2(~ ~ 5~2~eO q SiO2(~) ~ S02(g a H~300o ~ * ~5 In a normal copper smelting proce~s the most important factor in t~:rm~ of heat economy is the combination OI the reduc tion and ~lagging r~actio~s (Ia~II or Ib~II)o Signi~icant quantitie3 of copper oxidule, Cu20; will not ~e~in to appear in the lower part of t~e re~ction ~haft until the airm i~ a matte wlth a copper conoen~

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tration of more than 75% Cu or metallic copper. Even then, however, the magnetite must be reduced sufficiently so that thecopper losses into slag will not be immoderate. Thus, the reaction I+II is always significant. Other reactions occur to a small degree, but they are not very important in terms of heat economy. Besides these endothermal reactions there are thermal losses in the lower furnace as well.
According to current practice, oil, gas or coal is burned both below and along the reaction shaft to generate heat for the lower-furnace reactions and to replace the thermal losses. Under the reaction shaft, where ` 10 the endothermal reactions occur, the melt is well mixed owing to the generat-ing S02 gas, and the transfer of heat is effective, but elsewhere in the furnace, where the slag is almost stationary, the translfer of heat is poor.
; It has been verified by measurements that in such a stationary s~ag the temperature difference is 5-10C/cm. If the slag discharge temp~rature is 1250-1300C, its surface temperature can easily be 100C higher. Transfer of heat from the combustion gases through the slag is difficult because of the high surface temperature of the slag and because of counter-radiation.
The entire gas quantity must be heated to a high temperature and the thermal losses in the part above the furnace melt are great. Thus, the gas quan~ity increases and expensive gas treatment~devices, such as waste heat boiler, electric filter, blowers, must accordingly be dimensioned large.
The present invention provides a process for the suspension smelting of a finely-divided raw material selected from the class consisting of sul-fidic and sulfidic and oxidic ores and concentrates, wherein a suspension of particles of said finely-divided raw material, in an oxygen containing gas, is caused to flow downwards in a suspension reaction zone, said suspension reaction zone having an accumulated melt in the lower part thereof, in order to oxidize and at least partially smelt said raw material, whereafter the suspension flow is caused to flow sidewards perpendicularly to its original flow dire~tion so that most of the particles present in the suspension flow impinge against the surface ofsaid accumulated melt, and the remaining - suspension flow is directed into a rising-flow zone, and solids are separated ' -.

~ 3 ~3 fTom said remaining suspension flow, characterized in that all of the heat required for the smelting process is supplied to the particles falling down-wards in suspension in the suspension reaction zone.
According to the present invention the temperature of the particles falling downwards in the suspension reaction zone is regulated so that the heat content of the particles impinging against the melt covers the heat quantity required by the endothermal reactions occu~ingin the melt.
According to the process of the present invention the heat required for the smelting process may be supplied to the particles falling downwards in suspension in the suspension reaction zone by regulating the suspension flow velocity in the suspension reaction zone so that the delay period of the suspension therein is approximately the same as the period for oxidizing the raw material to such a degree that the heat of reaction generated during oxidation is sufficient to heat the particles to the desired temperature.
According to a preferred embodiment of the process of the present invention the suspension of particles of the finely-divided raw material is fed into the suspension reaction zone at a point which is about 2 to 6 meters above the surface of the accumulated melt.
Preferably, the heat required for the smelting process is supplied to the particles falling downwards in suspension in the suspension reaction zone while regulating the suspension flow velocity in the suspension reaction zone so that the average delay period of the suspension in the suspension reaction zone is approximately 0.5 to 2 seconds.
The oxygen containing gas may be air and/or oxygen. Preferably the oxgyen containing gas is p~eheated air and the heatr~uired for the smelting process is supplied to the particles falling downwards in suspension in the suspension reaction zone while regulating the preheating degree of the air. ~lternatively, the heat required for the smelting process may be supplied to the paTticles falling downwards in suspension in the suspension reaction zone while regulating the oxygen content of the air.

The heat required for the smelting process may be supplied to the particles falling downwards in suspension in the suspension reaction zone ~k~ 5 ~ ~ ~ Z 3 ~ 3 while regulating the raw material feed to said zone.
~hen the raw material has a low thermal value the heat required for the smelting process may be supplied to the particles falling downwards in suspension in the suspension reaction zone while adding fuel to said zone in addition to the raw material.
According to another aspect of the present invention there is provided a suspension smelting furnace for the suspension smelting of a fine-ly-divided raw material selected from the class consisting of sulfidic and sulfidic and oxidic ores and concentrates comprising a horizontal lower fur-nace to which the loweT ends of at least one vertical suspension reaction shaft and a rising flow shaft have been connected, with means at the upper ; end of the suspension reaction shaft adapted to produce a suspension ofparticles of said finely-divided raw material in an oxygen containing gas and adapted to direct said suspension downwards in the suspension reaction shaft against the surface of a melt accumulated in the lower furnace during opera-tion of the smelting furnace in order to discharge most of the suspension in-to said melt, and with devices in the portion of the lower furnace adjacent the rising flow shaft for withdrawing slag, metal and matte from the lower furnace, characterized in that in the suspension reaction shaft the distance between the suspension producing means and the melt is at maximum the same as the effective diameter of the suspension reaction shaft.
Preferably, the ratio of the distance between the suspension pro-ducing means and the melt to the effective diameter of the suspension reac-tion shaft is approximately 0.7 to 0.9.
According to the invention, the drawbacks of the current practice can be diminished in two ways. The reaction shaft may be shortened or originally made so short that the highest temperature and the highest reac-tion degree in the reaction shaft and the lower furnace part which is its continuation are reached just before the suspension is separated from the gases into the melt. Thereby savings are effected in the investment costs since the reaction shaft can be much lower than currently. In flash smelting systems the reaction shaft height and the heavy silo structures ~ - 5a -)~

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to be built on top of the shaft determine the height of the entire smelting system and thereby considerably affect the investment costs, as well as the operation costs (transfers of material up into the silos). Thermal losses are also diminished along with the shortening of the reaction shaft. This has an effect especially in cases in which the concentrate has a low thermal value and extra fuel must be used in the reaction shaft.
One alternative method is to install the raw material feeding device so that the distance of the feeding point from the melt surface can be adjusted to the desired length without having to change the length of the - 10 reaction shaft.

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The invention is described below in more detail with re-ference to the enclosed drawings, in which Pig. 1 is a section of a side view of an experimental flash smelting furnace, Figs. 2-4 illustrate the distribution of oxygen in the reaction shaft, Fig. 5 illustrates the oxidation of sulfides in the reaction shaft, Fig. 6 depicts the temperatures of the reaction shaft gas as a function of the reaction distance~ and Fig. 7 depicts the stability diagrams of various compounds as f~mctions of the oxygen and sulfur pressures.
~ le amount of heat required by the endothelmal reactions of the process is higher, the higher the concentration desired for the matte is. The experiments described below will illustrate this. The figures were calculated on the basis of the results obtained in an experi-mental furnace (Fig. 1, 1-2 t concentrate/h). There was no return of the ; flying dusts in the experiments but A
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-10~ 3 the sla~ and matte ~uantities ha~e been calculated on the basis of the obtained analy~qe~ as i~ there had been a co~!lplete recycling of ~he ~lying dusts, Thi3 doe~ not have, however~ a substantial eff~ct on the result o~ the obser~ations.
~opper concentrate analysis:
~u 1~. 0 ,~
~e ~8.5 S34~5 SiO~4.0 ~
~he oxygen wa~q analysed from the matte and ~e3~ from the ~lag, and the ~e304 concentrations were c21cll1a~ed o~ the basis therecf. T~e quantitie~ of matte a~d ixon ~emaini.rl.g .in the slag were calculated from its sulfux and copper~ The ~eU qua~tity formed acco~ding to Reaction I is obtained by ~ubtraoting th.e iron pxesent in the slag in~ e form o~ magnetite and, fuxther, the iron pxe~ent in it in the form of matte from the total irQr in the slag~ ~he heat of melting of magnetitep 138 X.J/mol, has been u ed as its heat of solution. All value~ have been calculated pex one m~tric ton of concentrate.
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~erime~t 1 Matte 327 kg Slag ~3 ~g Cu ~5cO ~ Cl~105 %
~e 20.0 % ~'e 46.8 S 21~ 9 ~/~ $ lo 6 %
0 2~1 ~ 3?e20~l13~5 %
SiO231~5 %
Na~netit;e quantity: in matte25 k~
in slag, 92 ~l ~ 1~7 k~
:~h~ ~a2~ quantity produced in the slag acco~di~ to R~ction II i.s 253 ~g~ which according to Reactiorl Ia~II reqllire3 `. a ~ea~ quant.ity of 345 x 10 kJ and according to React~on l.bTII~
159 x 103 ~J. ~he "diæ~olvi.ng~ of m~gnetite requires a heat quant~.ty o~ 69 x 103 ~

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'~hetQtal heat reguire~ent is 41~ x 103 kJ iX ~e30~ )9 or 103 kJi3~ ~e - ~ e~t 2 : .
~tte 240 kgSl~g 803 kg Cu 7303 % ~ulo~3 ~
~e 594 ~ Fe46~3 %
S 2005 ~6 S 0.4 ~
' 45% ~e3~_0 5 %
~i231~ 0 ,~
Magnetite qu~lty: ln matte 4 kg i n ~lag 1~9 kg '~he ~e2~ quantity p~oduced in the ~lag according to Reaotio~
II is 252 kgp wb..ioh according to Reaction Ia+II require~ a heat quantity of 345 ~ 10 k.T and accoxdi~g to Ib~II, 159 x 10 k~, 'l'he ~i~solving OI the magnetite requires a heat quall tity of lOQ x 103 kJ, '~he ~otal neat requiremellt i.~ 445 x 103 kJ 1~` Pe304 (9 or 159 x 10 kJ lf ~e304 ~1) - '~he real heat requirement is mo~t likely betwee~ the abov~
limits~
~ he obtained r e3ults are by no mRa~ absolute O It iæ not k~o~,m. preci~ely which reactions occ~u~ and how they real:Ly occ~
in -the r~action shaft. However, it is k:nown -I;hat a lowex~grade C~l matte can dissolve a ~rea~er guanti.~y o~ oxidiz~d lron at a ce~tai~ temperatureO
When l:he obaect is to o~t~in low~rade mat~e ,, t}~e heat reqllirc~ment approaches the m~ imllm, l~C~ x 103 ~J. Whe.n the ob~ie~
is a high-grade m~tte, onl~ pa~t of the o~idized iXOll Ca'l di;~lSOl~re in the ma t te drop~ 7 the xe~ t ~eing in tht? ~orm o:~ ~o:l.id mag:rleti te l'he heali ~equirem~nt approac~ the maxi~um in t;hat case~ ~he analysi~: re~ul~ wexe obtained from cooled ~ample~0 ~ooled sa~ple.s were also tak~n from the ~uspellsion falling .i.n t;he reaction shaI t, e~e samples we~ analy~ed~ gaæ analy3es were performerl~ and tempel~ture meas7lrem~nt3 were ~ken~ ould be obser~d micro~

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, - . :. : : ' :a ~3~ 3 Scopically from these samples that in the reaction sha~t the oxidized iron was practically in the form of magnetite, and that the slag-forming reactions ~MeO + SiO2) had not yet started, the SiO2 being usually unreacted. In the smelting experiments the concentrate had been dried to 0.1% H2O and did not contain particles over 2 mm. Figs. 2, 3 and 4 depict the distributions of oxygen in the reaction shaft under different smelting conditions. The 2 and SO2 contents are gas chromatographic analyses, and the 2 (FexOy) has been calculated as a balance, compounded with the solid (melt). It is clear-ly indicated in the figures that an almost permanent reaction result level is obtained in this experimental furnace even within a reaction distance of less than 2 m, almost independently of the conditions, gas velocity, feed ratc, oxygen concentration, and the preheating degree of the process air.
Pig. 5 shows the respective so-called copper matte concentrations and the final concentrations calculated from the reaction shaft solid analyses. It ~` can be noted therefore that under the experimental conditions the reaction shaft reactions led to a Cu matte with a concentration of approx. 40% and the final Cu matte with a concentration of approx. 60% was obtained in the lower furnace. It must be noted here that the points in Fig. 5 have been calcu-lated as containing only Cu2S + FeS (stoichiomO) and no dissolved magnetite.
In reality, for example, the 40-percent Cu matte also contains approx. 5%
oxygen so that the matte concentrations would in reality be considerably less than 40% Cu. Fig. 6 depicts the temperatures taken with a thermoelement from different heights in the reaction shaft. These measurements agree well with the analysis results in Figs~. 2, 3 and ~ and confirm the observation that most of the reactions occurring in the reaction shaft are completed within a distance of approx. 2 m. The conclusion from a theoretical observation of the transfer of heat and the reaction velocity in the reaction shaft was that the reaction velocity in the shaft is determined by the heating velocity of a particle alone, and that in this partial process the velocity difference between a particle and gas is of a considerable importance. After the kindl-ing of the concentrate, the role of the heats of reaction is ~ecisive in terms of the g _ : ~0''~ 3 ' ' ' behavior of -the entire ~u~penæion, ~he period o~ heat~ng a d~y conce~rate -particle to the kin.dling temperature under reaction shaft conditions is of the order of 0.1 s, i~e. 9 the kindling occur~ immediately under the vault of the reaction sha~t~ If 0 - 3'7 ~ is taken as the average si~e o~ a conoentrate par~ e9 67% of its s~fur can be burr~ed in 10 4 aeconds according to a calculatio~ based on gas di~usion~ Endothermal reactions and occw~rence~p such as th~ dec.omposition of ~ul~ates and carbonate~p the distill~tion of the p;yritic ~ulfur, ~h~ e~raporation of the hwmidity, and the micropelletiza~ion~ decel~rate bo~h the heati and t~he combustion reactions, Al~o~ a poox d~per~ion o~ the concentra~ion causes a con~iderable average deceleration o~ the reactions. Pyrite2 fox e~ample, can in ~uoh a c~se be found in the lower part of the reaction shaft~ and the concentrate c~n also form a pile in the lower furnace. In noxmal ca~s~ when the concentrate is dry c~nd finelydivided and the disper~ion is ~ood~ most o~ th~ exothermal reactions occ~ immedia~ely in the upper part o~ the reaction shaf~ c~d the endo~hermal one~ i~ the melt undex the reaction ~h~ft. q'he samples tciken ~rom the f~ash emelting furnace slag immediate]y after the reaction 3haft (a) a~d from the slag disch~r~e at the o~her elld o.~ th~ furnace (~
confirm the idea tha~ mos~ of the lower ~u~nace reactlon~ ha~e occl~rred immediately ~mder the r~action~aft a7~d ~hat; o~ly after~
reaction.s d~e to the settling of th~ dus t and sorne set tling of th~ ma-tt~ and ~he metal occur ln tl~e lower .~ ace in th~ par~
~o:llowin~ l;he ree.ction sha~t.
Cu % ~e % S % ~e304 ~ SiO2 %
a) 2,~ 43.3 0.5 17~5 3105 b) 2~4 43~5 0.3 1605 30.5 c~ 18~6 ~3,0 8~4 25~7 ~60 c) ~ corresponding shaIt sample prio~ to the lower ~urnace~
ll~en the concentrate possesses a s~icient quanti.t~y of heat o~ rea~tion and the reaction sha~t i.s ~ho~tened~ the temperat~re of the suspenæion xiæes by an c.mount corresponding tc the lowe~in~ o~ the the~mal losses. This is the ~ecolld considerable a~van-tage of` the inventiorl and it is put to use~.
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~his rise i~ the su~pen~ion temperature, the cha~ge in its enthalpy, is uæed i~ the endothermal reactions OCCUrriIlg in the lower ~ur~ac~ hus9 the ext,ra heat yielded by the exothermal oxida-ticn reactions in -the react~on ~haft i~ used ef~ectivel~
i~ the endothermal xeductio~ and ~lag form.i~g r~actions in t~le lower furnaceO ~he effec~ive~ess mu~-t be unders-~ood so t~at t}~e partiole~ whi.ch are to react with each other elldothermally in th~ lower furllace ~lready contain the requisite quan-tity of heat, which need not, a~ in eurren-t practice 9 ~e pro~iaed by bul~ning some fuel under or near the reaction shaft~
~ he in~en-tion is de~cribed below in more detall with re~exence to example~.
Observa~ion~ are made of an industrial~scale f].ash snelting f~rnace, in which the inner diameter o~ the react~on ~ha~t was

4.2 m and its height 7.5 m. In addition, the reaction dist~ce to the melt was app.rox~2 m i~ the lower furnace~ ~he measured ~ thermal lo~ses in the reaotio~ shaft were 5430 x 103 kJ/h t 15,~'~
lthe ~eed was app~o~. 30 t,/h pltls 10~ circulati~g ~ly~g dusto : '~he proce~ air W2~ pr~heated.to approxO 200C a~1 enrich~d wi-th oxygen to 32/~o 2~
T~he reaotion ~haft ~a.,~ autogenic - no additional fuel - and ~he temperature of the su,~pen~ion falllng into the lower furna~e was approxO 1300C.
Oil was b~r~ed ~lde:r thc reaction sha~t at ~he rate of 200 kg/h and el~e~There in the furnace at appro~O 250 kg~h~ ~he lower heat va].ue heir.g 1~o6 o 103 kJ ~di~charge shaft; 1~00C~
T~he aver~ge c~i~cha~e temperature of ~he sla~ was app~o~O 12.~(~C
~ld that of matte ~ppro~Q 1180~ T~he tem~era-t~re of t.he lower furnace discharge gases was approxO 1400C or morev . ~ ~

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Copper co~centrate mixture ~lying 2ust :Eeed ` ~naly~ 4nalysi~:
Cu 18 . ~ % ~u 25 ~ 10 %
~e 28,5 % ~e 24.30 5~
S 2~7 % S 7.. 30 %
Zn 1~9 % 7,n 5.50 %
SiO2 16.8 % Pb ~ .70 %
other ,~ SiO2 3.70 %
100,.0 % oxyge~
oth~r ,~2 ~0. 0 o~O
Mat-te 255 kgJt concentxa,te Slag 620 kg/t ~o.ncentxate ~alysis: ~aly~is:
Cu 70,0 % Cu . 1.9 %
~e 803 % ~e 42.6 %
. S ~1.2 ',~ S 0~5 %
0 0~,46 % Zn 2609 ~e3o~ 15~8',~
MgO~CaO l o 9 A123 ~ ~ O
Material balance of' xeac tion ~haf~ per 1 ton concentrate In:
Concent~ate 1000 kg ~lyln~ dust 3 lt)O
Oxygen 20~3 m n 29'7 Nl~xo~,~erl 442 m3n 553 '' :L95~ g ~ut:
Melt~solia ~uspension . 900 kg Oxideæ o~ flying du~t 81 "
Nitro~en 442 m3n 553 t, . Sul~ur vxide 1~ ~3n 412 "
n~g~}l 3 ~13~ 4 It ~ 1950 kg :

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'3 Exampl0 The oil used in the lower furnace, 450 kg/h, is replaced byraising the temperature of ~he shaft product. The obtained available heat is approx. 210 x 103 kJ/h, tcon , when ~he lower-furnace discharge gases are at 1400C. When the matte is discharged at the other end of the lower fur-nace and not under the reaction shaft, the temperature of tlle lower-furnace discharge gases can be allowed to drop to 1350C, whereby the lower-furnace heat requirement is decreased to approx. 157 x 103 kJ/h, tcon .
The change of the heat content of the shaft products between 1300 and 1400C.
Melt + solid suspension 0.8 . 103 kJ/C, t concentrate ~ e3 4~1)) 3 Process gases 1.0 . 10 kJ/ - " -Flying dust 0.06. 103 kJ/ - " -Total 1.9 . 103 kJ/ C, t. concentrate The temperature of the shaft product must be raised 157 x 10 kJ/h~ tcOn. = 83C

1.9 x 103 kJ/C, tcon This means that the reaction shaft must be shortened from the present 7.5 m to approx. 1-1.5 m. Thereby the quantity of gas withdrawn from the flash smelting furnace is reduced by approx. 5100 m3n/h, which is approx. 22%. This freed gas volume can be used for increasing the capacity according to the following example.
Example Z
Increasing the capacity by approx. 29%. A furnace according to Example I and the same oxygen concentration, 32% 2' are used. The gas volume freed from the burning of oil, 5100 m3n/h, is used in the reaction shaft for the oxidation of additional concentrate. This means a concentrate addition of approx- 8.7 tcon /h, i.e., approx. Z9%, and an increase in the shaft product temperature by approx. 30-40C from the value in Example 1.

The gas volume and the gas treatment devices remain the same.

~ 3 Example 3 Lowering of investment costs. A new plant :is constructed with the feed and oxygen enrichment values of the old plant. Owing to the shortening of the reaction shaft, as set forth in the invention, the smelt-ing plant building will be approx. 6 m lower and the gas treatment devices approx. 27% smaller, This means not only a considerable lowering in the - investment costs, but also a lowering in the operation costs, ~or the feed material of the flash smelting furnace need not be lifted as high as in the old plant, and the smaller gas treatment units naturally also mean lower operation costs. Also, the short reaction shaft needs only a fraction of the fireproof lining material needed for the long shaft of current practice.
Example 4 Increasing the capacity sharply by allowing the reaction shaft product temperature to rise higher than the conventional -temperature. Ihe reaction shaft is shortened from an old one as in Example 1 or a new plant of the respective height is constructed. If the gas rate is maintained the same as before, the oxygen concentration of the process air must be increased in order to increase the capacity. In Example 2, a capacity of 38.7 tcon /h was obtained with an oxygen concentration o~ 32%. If the oxygen concentra-tion is increased to 50%, the feed capacity increases to 65 tcon /h, i.e.,more than 67%. If the cooling is not made more efective in the reaction shaft and the front part of the lower furnace, the shaft product temperatures rise by approx. 300-400C. In practice increasesin the temperatures of the shaft products and the lower-furnace melts also increase thermal losses.
~hen temperature increases as great as this are involved, special attention must, however, be paid to effective cooling. This can be effected by some known method, e.g. by forced-circulation pressure water cooling, whereby most of the thermal losses can be recovered in the form of vapor, In addition to the increase in capacity, another considerable advantage is also gained by the high reaction temperature according to this example. When the tempera-ture increases, the tendency of the iron to oxidi~e into magnetite is sharply diminished. This is indicated in Fig. 7, .'` ~

l~)ti~3~3 .
which show3 the sta'oility diagram~ of iron a~d copper compol~ds at diffe~ent te~peraturesO ~he val.ue.s ha~e '~een partly obtai.ned by ext~apol~tion f~om lower temperat~es~ It can be noted from them that when the temperatl~e ri~.e3 the o~ygen pxe~w~e3 cor~
responding ~o thQ equilibrium ~eO/~e30~ al~o riseO ~hu~., for e~ample~
~emperature 1~00C; pO = 10-7-6 atm 1500C; pO -. 10-5-~ atm 1700a; pO = ~.o~3-2 atm In a similar manner a tempexatl~e increase promotes ~he :Eormation of metallic eopper accord~.n~ to the s~ability diagra~
Cu/Cll20. ~hus~ it i~ possibie ~o prod~ce9 more ea~ily than beforep metallio copper dil~ectly from fer~ifexou3 copper ooncentrates already in the reaction shaft of the ~ sh smel~ing ~urnace, A
high reaction temperature can also be used in smalting so-called mixed co~centratesr ~hese mlxed concentrates often contain9 in additiox~ to copper concentrateg considerable qu~ltities o~ fox example, ~inc, lead and other compo~nds which can~ot ba se~ara~ed by ~onventional methods9 a.g. 9 by froth ~lotatio~. It is d:ifficul~;
to use them effec~ively in any current process~ ~`he high tempera~
ture ~e~t`ioned in this exampl~9 however, give~C~ good pos~ibill.ti~
for processing e~en these mixed conce~trates~ It is knOl~rA tha~
the vapor pre~C3sl~es of the compGunds of' these mate~ials pre~ent as impurities, ~uch as zinc~ lead9 c~seni~, an~imony9 all~ bi,s~u-~h~
inc~aa~e shc~rpi~ along ~rith temera-ture~ and thus it i~ possi.ble a~ a ~ligh temperat~Lre to coneen~;ra~e them into the f1~ring dust~3 fro~ ~he aotual basic concenJ~Jrate. ~he~e ~aluable components pre~e.~lt a~ impt~ities C~l thus be proce~sed separately by ~lo~n me-~ho~s~
al~d first~grade metal ca~ be proces~ed ~xom ~he act~ asic ooncerltra.te~ u~u~ copper ~ ncentr~te~
More~ example~ could ~aturally be g.i~en c~ the advantage~
an~ use~ o~ the i~vention but we assume t}lese will al~eady elucldat.e th~ matter su.~ficientlyO ~'he fo~lo~Jir~g is a summary o.~ the advar.
ta~es ~ d pos~ibi~ities provide~. ~y the i~ven~ion~
- Energy i.~ oave~ si~ce the~ therm~1 enexgy prese,lt in t.he con~
centrate .is u~d in the pxoc~s~ ~s ~f:Pectively a,q po~s:i~le..
he inves~ment and o~eration co~t~ of smeltlng pl~n~ ars :~ .
: .
, 1~7~;3~3 reduced sirLce th~ ~eaction ~h~ft and the entire smelting plar~tcan be ma.de c~ucially lo~Ye~ .in compc~rison ~.ith current pxactice~
~ Since fllel is not needed ln the lower flu~na~e~ +vhe ga5 volwmes and gas treatment un.its are at a ~inimwnt whi.cil lowers both lnvestment a~d operation costs~ .
I~.e cap~city o~ c~n old plant can be lncrea~ed considerably since oil is not buxned i~ the lower furr~ace.
~ Amon~ other things, the direct manufacture of copper eve~ ~rom normal9 ellalcoryr:ltic copper co~centrates in a ~lash smelting ~urnace is facilitated~
- ~he usc of so called mixed concentra~es ~or copper production is fcacilitate,l since at high reactioll ternperatures the volatile components can be concentrated separately in the flyin~; dust~
~ ~en high temperatl~es c~re used~ the .increased thelimal losses necessary for the endurance of the devices, can be recovered in the fo:rm of vapo~.

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Claims (12)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A process for the suspension smelting of a finely-divided raw material selected from the class consisting of sulfidic and sulfidic and oxidic ores and concentrates, wherein a suspension of particles of said finely-divided raw material, in an oxygen containing gas, is caused to flow downwards in a suspension reaction zone, said suspension reaction zone having an accumulated melt in the lower part thereof, in order to oxidize and at least partially smelt said raw material, whereafter the suspension flow is caused to flow sidewards perpendicularly to its original flow direction, so that most of the particles present in the suspension flow impinge against the surface of said accumulated melt, and the remaining suspension flow is directed into a rising-flow zone, and solids are separated from said remaining suspension flow, characterized in that all of the heat required for the smelting process is supplied to the particles falling downwards in suspension in the suspension reaction zone.

2. A process according to claim 1 characterized in that said suspen-sion of particles of said finely-divided raw material is fed into the sus-pension reaction zone at a point which is about 2 to 6 meters above the surface of said accumulated melt.

3. A process according to claim 1 characterized in that the heat required for the smelting process is supplied to the particles falling down-wards in suspension in the suspension reaction zone by regulating the sus-pension flow velocity in the suspension reaction zone so that the delay period of the suspension therein is approximately the same as the period required for oxidizing said raw material to such a degree that the heat of reaction generated during oxidation is sufficient to heat said particles to the desired temperature.

4. A process according to claim 1 characterized in that the heat required for the smelting process is supplied to the particles falling down-wards in suspension in the suspension reaction zone while regulating the suspension flow velocity in the suspension reaction zone so that the average delay period of the suspension in the suspension reaction zone is approximate-ly 0.5 to 2 seconds.

5. A process according to claim 1 characterized in that the heat required for the smelting process is supplied to the particles falling down-wards in suspension in the suspension reaction zone while regulating the raw material feed to said zone.

6. A process according to claim 1 characterized in that said oxygen containing gas is preheated air and the heat required for the smelting process is supplied to the particles falling downwards in suspension in the suspension reaction zone while regulating the preheating degree of the air.

7. A process according to claim 1 characterized in that said oxygen containing gas is air and the heat required for the smelting process is supplied to the particles falling downwards in suspension in the suspension reaction zone while regulating the oxygen concentration of the air.

8. A process according to claim 1 wherein the raw material has a low thermal value characterized in that the heat required for the smelting process is supplied to the particles falling downwards in suspension in the suspension reaction zone while adding fuel to said zone in addition to the raw material.

9. A process according to claim 1 characterized in that said suspen-sion of particles of said finely divided raw material is fed into the suspension reaction zone at a point which is about 2 to 6 meters above the surface of said accumulated melt and in that the heat required for the smelting process is supplied to the particles falling downwards in suspen-sion in the suspension zone while regulating the suspension flow velocity in the suspension reaction zone so that the average delay period of the suspension in the suspension reaction zone is approximately 0.5 to 2 seconds.

10. A process according to claim 9 characterized in that said oxygen containing gas is preheated air.

11. A suspension smelting furnace for the suspension smelting of a finely-divided raw material selected from the class consisting of sulfidic and sulfidic and oxidic ores and concentrates comprising a horizontal lower furnace to which the lower ends of at least one vertical suspension reaction shaft and a rising flow shaft have been connected, with means at the upper end of the suspension reaction shaft adapted to produce a suspension of particles of said finely-divided raw material in an oxygen containing gas and adapted to direct said suspension downwards in the suspension reaction shaft against the surface of a melt accumulated in the lower furnace during operation of the smelting furnace in order to discharge most of the suspension into said melt, and with devices in the portion of the lower furnace adjacent the rising flow shaft for withdrawing slag, metal and matte from the lower furnace, characterized in that in the suspension reaction shaft the distance between the suspension producing means and the melt is at maximum the same as the effective diameter of the suspension reaction shaft.

12. A suspension smelting furnace according to claim 9, characterized in that the ratio of the distance between the suspension producing means and the melt to the effective diameter of the suspension reaction shaft is approximately 0.7 to 0.9.