SE183731C1

SE183731C1 -

Info

Publication number: SE183731C1
Authority: SE
Publication date: 1963-01-01

Description

Uppfinnare: G H C Norman Prioritet begard frau den 4 juni 1952 (Kanada) Denna uppfinning avser rostning av metallsulfider, sasom pyrit och pyrrotit, i en oxiderande gas for bildning av en oxidprodukt. Uppfinningen Sr sarskilt tillampbar pa rostning av jarnsulfider i andamal att antingen framstalla en rostningsprodukt, som lampar sig fOr extrahering av metallen genom exempelvis selektiv reduktion atfoljd av ammoniakalisk lakning eller selektiv sulfatering atfiiljd av vattenlakning, eller att framstalla jarnoxid av hog kvalitet avsedd for direkt smaltning till jam n och stal utan ytterligare avsvavling. Inventor: G H C Norman Priority Required from June 4, 1952 (Canada) This invention relates to the roasting of metal sulfides, such as pyrite and pyrrotite, in an oxidizing gas to form an oxide product. The invention is particularly applicable to the roasting of ferrous sulphides in order to either produce a roasting product which is suitable for extraction of the metal by, for example, selective reduction followed by ammoniacal leaching or selective sulphation accompanied by water leaching, or to produce ferrous oxide of direct oxide. jam n and stole without further desulfurization.

Ehuru det uppenbarligen Sr Onskvart att utfora rostningen av sulfiderna i fluidiserade badd, har det hittills befunnits nodvandigt att inmata sulfiden i apparatens rostningszon med lag hastighet, om svavelhalten i den rostade produkten skall nedbringas till ett lagt varde. Urn matningshastigheten till en fluidiserad badd har varit hog, med en motsvarande hog gashastighet, her den som sulfid i rostningsprodukten narvarande svavelmangden varit hog, emedan de finare partiklarna ha bunts ut ur ugnen av gasen och de ha salunda icke kvarhallits i ugnen under tillra.ckligt lang tid. Although it is obviously difficult to carry out the roasting of the sulphides in fluidized baths, it has hitherto been found necessary to feed the sulphide into the roasting zone of the apparatus at low speed, if the sulfur content of the roasted product is to be reduced to a given value. The feed rate to a fluidized bath has been high, with a correspondingly high gas velocity, here the sulfur content present as sulphide in the roasting product has been high, because the finer particles have been bundled out of the furnace by the gas and they have thus not been retained in the furnace. long time.

FOreliggande uppfinning avser ett rostningsforfarande, vid vilket fasta partiklar av en metallsulfid kontinuerligt inmatas i en ugn och dar rostas i fluidiserad badd i en strom av oxiderande gas under bildning av en rostningsprodukt, partiklar av rostningsprodukten kontinuerligt bortferas i en mangd, som Sr ekvivalent med mangden kontinuerligt inmatad orostad sulfid, och varvid gasstrommens hastighet Sr sadan att den Iran badden bortfor partiklar, varav en del aterforas till badden. Forfarandet kannetecknas darav, att man avskiljer de av gasstrommen frail badden bortfOrda partiklarna ur gasstrommen och Aterinfor dem i badden i sadan mangd per tidsenhet, att viktforhallandet mellan de ur gasstrommen avskiljda och till badden aterforda fasta partiklarna och den i badden under samma tid inmatade orostade sulfiden Sr hogre an 1:1. The present invention relates to a roasting process in which solid particles of a metal sulphide are continuously fed into an oven and then roasted in a fluidized bath in a stream of oxidizing gas to form a roasting product, particles of the roasting product are continuously removed in an amount equivalent to the amount continuously fed unroasted sulphide, and the velocity of the gas stream is such that the Iran bath removes particles, some of which are returned to the bath. The process can be characterized by separating the particles removed from the gas stream from the bath from the gas stream and re-introducing them into the bath in such quantity per unit time, that the weight ratio between the solid particles separated from the gas stream and the bath fed back into the bath at the same time Sr hogre an 1: 1.

Det liar hittills varit brukligt att till den fluidiserade badden aterfora det stoft, som uppsamlas frail den avgaende gasen. Detta stoft har emellertid vanligen endast utgjorts ay det stoft, som oundvikligen foreligger i gasen, och inlet forst& har gjorts att Oka halten ay fasta amnen i den utgaende gasen till en mangd, som Sr hogre an den mangd ramaterial, som infores i den fluidiserade badden, i avsikt att aterfOra mera av namnda fasta amnen dn mad som infOres som ramaterial. Genom att partildarna av dessa fasta anmen aterinforas i badden pa. sattet enligt uppfinningen, bringas de att i medeltal genomga. badden foretradesvis minst fern ganger och den genomsnittliga svavelhalten hos den rostade produkten reduceras till det enskade laga vardet. Until now, it has been customary to return to the fluidized bath the dust which is collected from the exhaust gas. However, this dust has usually only been present in the dust which is inevitably present in the gas, and it has been understood that the solids content of the outgoing gas is increased to an amount which is higher than the amount of raw material introduced into the fluidized bath. , with a view to returning more of the said solid substances dn mad as infOres as raw material. By reintroducing the batches of these solids into the bath. method according to the invention, they are made to undergo on average. the bath is preferably at least four times and the average sulfur content of the roasted product is reduced to the desired legal value.

Lampligen Sr forhallandet mellan vikten av de till badden Sterforda fasta partiklarna och vikten av de inmatade, orostade partildarna stone an 10:1, och det kan mama annu hogre. Lampligen Sr ratio between the weight of the solid particles to the bath Sterforda and the weight of the fed, unroasted particle stones a 10: 1, and it may mama annu higher.

Med hjalp av uppfinningen Sr det mOjligt att avsvavla sulfiderna till en mycket lag svavelhalt, Sven yid hoga matningshastigheter ay omkring 11-22 ton per dag per in area hos harden i rostningsugnen. Svavel, som fOreligger i den rostade produkten i annan form an som sulfid, foreligger vanligen i form av sulfat, och detta svavel kan eventuellt avlagsnas genom vattenlakning. Om sulfatsvavel Sr skadligt i slutprodukten, kan halten darav minskas genom anvandning av hoga rostningstemperaturer och genom alt man undviker att olampligt utsatta den rostade produkten Itir svavelhaltiga gaser under kylningen. With the help of the invention it is possible to desulphurize the sulphides to a very low sulfur content, Sven yid high feed rates ay about 11-22 tons per day per in area of the hard in the roasting oven. Sulfur, which is present in the roasted product in a form other than sulphide, is usually in the form of sulphate, and this sulfur may optionally be removed by water leaching. If sulphate sulfur is harmful in the final product, its content can be reduced by using high roasting temperatures and by avoiding inadvertently exposing the roasted product to sulfur-containing gases during cooling.

Vid forfarandet enligt uppfinningen fluidiseras de fasta sulfielpartiklarna medelst den oxiderande 2-- . gasen under bildning av en tat fas, och de fasta partiklar, &nil skola aterforas till badden, baras ut ur apparaten av gasen. De a-vskiljas Iran gasen i en separator, vilken kan vara en cyklonseparator, och vilken bor vara tillrackligt effektiv f Or att a-vskilja en avsevard del av partiklarna frail gasen. Den behover icke avskilja alla parLiklarna, eftersom en del av partiklarna kunna utgora en del av eller hela den fardigrostade produkten. Alternativt kan i huvudsak hela den fardiga rostade produkten avlagsnas separat Iran badden. In the process of the invention, the solid sulfyl particles are fluidized by the oxidizing 2--. the gas during the formation of a tat phase, and the solid particles, which must be returned to the bath, are carried out of the apparatus by the gas. They are separated from the Iran gas in a separator, which may be a cyclone separator, and which should be sufficiently efficient to separate a significant portion of the particles from the gas. It does not need to separate all the particles, as some of the particles may form part or all of the finished product. Alternatively, essentially the entire finished roasted product can be removed separately from the Iran bath.

Vid den normala driften av en fluidiserad badd installes gashastigheten sa, att partildarna Hiles i turbulent rorelse i rostningsugnen, varvid massan ferhaller sig som om den yore en vatska och vanligen avlagsnas genom en sidooppning overst i den turbulenta badden. Enligt foreliggande uppfinning är gashastigheten hogre, O. aft partiklarna standigt baras ut ur kammaren av gasstrommen. Massan av partiklarna bildar en tat fas i turbulent rOrelse vid kammarens botten u.tan nagon klart avgransad niva. OvanfOr den tata fasen finnas partiklar som baras uppat av gasen. Partiklarna aro av varierande storlek, och de storre partiklarna vilka erfordra langre rostningstid, baras icke uppat sa latt och strava darfor att kvarhliva langre i badden. During the normal operation of a fluidized bath, the gas velocity is installed so that the particles Hiles in turbulent motion in the roasting furnace, the mass behaving as if it were a liquid and usually deposited through a side opening at the top of the turbulent bath. According to the present invention, the gas velocity is higher, since the particles are constantly carried out of the chamber by the gas stream. The mass of the particles forms a tat phase in turbulent motion at the bottom of the chamber without any clearly defined level. Above the tata phase are particles carried upwards by the gas. The particles are of varying size, and the larger particles, which require a longer roasting time, are not carried upwards so easily and therefore strive to remain longer in the bath.

De i badden .inmatade fasta partiklarna skola ara av sadan storlek, att ej mer an 20 % av dem kvarhallas pa en sikt med 26 inaskor/cm. Om snlfidmaterialet skall lakas efter rostningen, exempelvis om det är eft pyrrotitkoncentrat, dr det Iampligast att de fasta partiklarna Arc finare, exempelvis av skim storlek att ej mer an 10 % av dem kvarhallas pa en 80 maskors sikt (200 mesh B.S.S.). s Den. oxiderande gasen bör fOretradesvis innehalla friLt syre oak kan utgoras av luft. Den temperatur, vid vilken rostningen intraffar, dr foretradesvis mellan 590 och 900° C. Eventuellt kan temperaturen regleras genom att ett kylfluidum ledes genom slingor i badden. Ett annat satt att reglera temperaturen bestar i aft partiellt kyla de fasta partiklar, som aterforas till badden. The solid particles fed into the bath should be of such a size that no more than 20% of them are retained in a sieve with 26 increments / cm. If the slurry material is to be leached after roasting, for example if it is after pyrotite concentrate, it is most appropriate that the solid particles Arc finer, for example of skim size that no more than 10% of them are retained on an 80 mesh screen (200 mesh B.S.S.). s Den. The oxidizing gas should preferably contain free oxygen which can be constituted by air. The temperature at which the roasting occurs is preferably between 590 and 900 ° C. Optionally, the temperature can be controlled by passing a cooling fluid through loops in the bath. Another way of regulating the temperature is to partially cool the solid particles which are returned to the bath.

Den hastighet, med vilken den oxiderande gasen ledes genom ugnen, bOr vara mellan 45 och 150 cm/sek (och vanligen 60-120 cm/sek) i den byre delen ovanfor den tata fasen. A.ven hogre gashastigheter kunna anvandas, beroende pa den sarskilda partikelstorleken hos det material som skall rostas och pa den mangd, i vilken materialet inmatas i badden. Trycket hos den oxiderande gas, som infores i kammaren, dr vanligen mellan 70 och 350 g/cm2. The speed at which the oxidizing gas is passed through the furnace should be between 45 and 150 cm / sec (and usually 60-120 cm / sec) in the upper part above the dense phase. Even higher gas velocities can be used, depending on the particular particle size of the material to be roasted and on the amount in which the material is fed into the bath. The pressure of the oxidizing gas introduced into the chamber is usually between 70 and 350 g / cm 2.

Det ar onskvart aft Ma forhallandena i rostningsugnen stabila och f Or detta andamal erfordras reglering av mangden partiklar. Regleringen kan astadkommas genom avledning av en del av eller hela den fardiga rostade produkten separat frau gasstrommen, som medfOr partiklarna, vilka aterforas till badden. Denna separata avledning kan utforas pa tva olika satt. For _det forsta kan en del. gas, som medfOr partiklar, avlagsnas fran ovre delen av ugnen men ledas forbi separatorn, fran vilken partiklarna aterfOras till badden. For det andra kunna partiklarna avledas under inverkan av deras tyngd eller med hjalp av en skruvtransportor genom en eller flera sidappningar i rostningskammaren, och denna avledning sker vanligen kontinuerligt men kan eventuellt ske intermittent. PA detta saft avledda partiklar maste ha bunks uppat av gasen och ha fallit nedat igen i -viss utstrackning. Vid det foredragna arrangemanget finnas Hera sidooppningar anordnade att uppfanga nedat fallande partiklar och de aro anbringade Over den tata fasen. The conditions in the roasting oven are stable and for this purpose regulation of the amount of particles is required. The control can be accomplished by diverting some or all of the finished roasted product separately from the gas stream entrained by the particles which are returned to the bath. This separate derivation can be performed in two different ways. For _the first can a part. gas, which carries particles, is deposited from the upper part of the furnace but is led past the separator, from which the particles are returned to the bath. Secondly, the particles can be diverted under the influence of their weight or with the aid of a screw conveyor through one or more side openings in the roasting chamber, and this diverting usually takes place continuously but can possibly take place intermittently. Particles derived from this juice must have bunked up by the gas and fallen down again to some extent. In the preferred arrangement, Hera side openings are provided to trap falling particles and they are arranged over the tata phase.

Gasen med medfOrda partildar, vilken ledes forbi huvudseparatorn, ledes fOretradesvis till en andra separator, till vilken aven gasen fran den forsta separatorn kan ledas, sa aLL man fran denna avlagsnar alla partiklar, vilka avskilts i den forsta separatorn. The entrained gas, which is passed past the main separator, is preferably passed to a second separator, to which the gas from the first separator can also be passed, so that all particles separated in the first separator are removed from it.

Det inses naturligtvis, att endast sa mycket rostat material maste avledas separat antingen vid apparatens topp eller genom sidouLlopp, som utgor mindre An 1/5 av de partiklar som aterforas till badden fran den fOrsta separatorn, och om ej alla partiklarna, som inforas i den fOrsta separatorn, aterftiras till hadden, maste den separat avledda fraktionen vara annu mindre. Genom lamplig reglering av den separata avledningen kan man uppratta jamvikt mellan mangderna ingaende rasulfid och utgaende rostad produkt. It will be appreciated, of course, that only so much rusted material must be discharged separately either at the top of the apparatus or through side outlets which make up less than 1/5 of the particles returned to the bath from the first separator, and if not all the particles introduced into it. the first separator, returned to the hadden, the separately derived fraction must be even smaller. By appropriate regulation of the separate diversion, a balance can be established between the amounts of incoming rasulfide and outgoing roasted product.

- PA den bifogade ritningen visas schematiskt en apparat, som lampar sig for utforande av forfarandet enligt uppfinningen. The accompanying drawing schematically shows an apparatus which is suitable for carrying out the method according to the invention.

En ugnskammare 2 omfattar en isolerande eldfast bekla.dnad 3 innanf Or en ogenomtranglig stalmantel 4. Ugnskammaren ar forsedd med lampliga brannare (ej visade) fOr att forvarma kammaren till en tillrackligt hog temperatur for aft igangsatta den exotermiska rostningsreaktion.en mellan de finfordelade sulfiderna och den oxiderande gasen. Fasta partiklar av ett metallsulfidmaterial inforas genom ett inlopp 1 i den forvarmda -kammaren 2. Luft eller annan oxiderande gas infores under ett tryck av omkring 140 g/cm2 genom ett ror -till en gasfOrdelare 6, varifran den strommar in i den fOrvarmda kammaren 2 genom iippningar 7 och fluidiserar partiklarna. oppningarna 7 aro fOrsedda med huvar 8 for att forhindra instromning av fasta partiklar nar gasstrommen stoppas. Rostningstemperaturen regleras med hjalp av ett kylfluidum som strommar genom rbr 10. Temperaturen regleras aven genom uppdelning av gasf Ordelaren 6 i sidled medelst mellanvaggar 11, varigenom man separat reglerar den luft som inkommer I zonen narmast kylrOren. Varma forbranningsgaser, som Arc rika pa SO2 och medfOrda fasta partiklar, stiga upp till ett utlopp 12 och instromma i en forsta cyklonseparator 13, fran vilken gas fortsatter till en andra separator 14 och en gagrenare 15. Avloppsgaserna avga genom ett ror 20. Minst 80 % av de fasta partiklar, som genomga utloppet 12, aterforas genom inloppet 16 till badden. An oven chamber 2 comprises an insulating refractory cladding 3 inside an impermeable steel jacket 4. The oven chamber is provided with suitable burners (not shown) for preheating the chamber to a sufficiently high temperature to initiate the exothermic roasting reaction between the finely divided sulphides and the oxidizing gas. Solid particles of a metal sulphide material are introduced through an inlet 1 into the preheated chamber 2. Air or other oxidizing gas is introduced under a pressure of about 140 g / cm 2 through a tube into a gas distributor 6, from where it flows into the preheated chamber 2. through openings 7 and fluidizes the particles. the openings 7 are provided with hoods 8 to prevent the inflow of solid particles when the gas flow is stopped. The roasting temperature is regulated by means of a cooling fluid flowing through tube 10. The temperature is also controlled by dividing the gas divider 6 laterally by means of intermediate walls 11, whereby the air entering the zone closest to the cooling tube is separately regulated. Hot combustion gases, such as Arc rich in SO2 and entrained solid particles, rise to an outlet 12 and flow into a first cyclone separator 13, from which gas proceeds to a second separator 14 and a branch manifold 15. The exhaust gases escape through a pipe 20. At least 80 % of the solid particles passing through the outlet 12 are returned through the inlet 16 to the bath.

Det finnes en envagsventil 21 fOr att hindra gaser - -3 och fasta partiklar fran att lamna kammaren genom inloppet 16. There is a one-way valve 21 to prevent gases - -3 and solid particles from leaving the chamber through the inlet 16.

Forhallandena Mom kammaren regleras genom avledning av fasta partiklar genom utlopp 17, som regleras av ventiler 22. Plattor 19 inskjuta i kammaren fOr att uppfanga partiklar, vilka ha bunts Over dem av den uppatstigande gasen och vilka rora sig nedat i ell jamfOrelsevis dot utrymme strax ovanfer plattorna. Partiklarna avledas genom ett ror 26 forbi en las 28 for att forhindra forlust av gaser. Del eller de utlopp som skola oppnas am beroende av den behandlade mangclen material, de inmatade partiklarnas storlek, storleken av oppningarna i utloppen 17, den erforderliga graden av eliminering av sulfidsvavel, rostningstemperaturen, det anvanda atercirkulationsferhallandet osv. Sarskilt fordelaktigt kan partikelstorleken hos det rostade materialet regleras i viss utstrackning, eftersom stiirre partiklar avledas genom de nedre oppningarna. The conditions of the chamber are regulated by diverting solid particles through outlet 17, which is controlled by valves 22. Plates 19 insert into the chamber to receive particles which have bundles above them of the ascending gas and which move downwards in a comparable dot space just above the plates. The particles are diverted through a tube 26 past a weld 28 to prevent gas loss. Part or outlets to be opened depend on the amount of material treated, the size of the particles fed, the size of the openings in the outlets 17, the degree of sulfur sulfur elimination required, the roasting temperature, the recirculation ratio used, and so on. Particularly advantageously, the particle size of the roasted material can be controlled to a certain extent, since larger particles are diverted through the lower openings.

Som exempel liar en sidoutloppsoppning 17 av 25 cm diameter och belagen 2,1 m ever harden anvants for att halla en tdt f as av 1 m hOjd i en ugn med 2,25 m diameter vid rostning av pyrrotitkoncentrat med en sadan finlek, att endast 5 % bike genomgar en sikt med 80 maskoricm. Tvangsavledning av fasta partiklar genom utloppen 17 ãr icke erforderlig, eftersom en Overraskande stor mangd partiklar instromma i utloppen 17 och a.vlagsnas pd grund av sin tyngd. As an example, a side outlet opening 17 of 25 cm diameter and coated 2.1 m hardener is used to hold a tdt phase of 1 m height in an oven of 2.25 m diameter when roasting pyrrotite concentrate with such a fine size that only 5% bike undergoes a sight with 80 maskoricm. Forced diversion of solid particles through the outlets 17 is not necessary, since a surprisingly large amount of particles flow into the outlets 17 and are removed due to their weight.

Den tata fasens djup kan dven regleras genom avledning av avloppsgaser medforande fasta partiklar genom ett utlopp 18, som regleras av en ventil 24. Dessa ga fOrbi cyklonen 13. The depth of the tata phase can also be controlled by diverting effluent gases carrying solid particles through an outlet 18, which is regulated by a valve 24. These pass the cyclone 13.

Ett .exempel skall nu lamnas pa anvandningen av den pa ritningen visade apparaten. An example will now be given of the use of the apparatus shown in the drawing.

Ett finfordelat pyrrotitkoncentrat innehallande 36 % svavel och omkring 5 % silikatgangart inmata,des i kammaren 2, vilken hade en invandig diameter av 60 cm och forvarmdes till en tempera-tar Over ° C. Den tata fasen lick bildas till varierande hOjd. Luft i en mangd, som teoretiskt liverstiger den mangd, vilken erfordrades for att forbranna pyrrotiten till Fe203 och SO2, infordes genom roret 5. De pa detta satt erhallna resultaten anges i foljande tabell: SulfidRost- matnings- fling hastighet Temp, kg/tim•°C Avloppsgas % SO, , %O, Rostad produkt % mad- % totalt svavel svavel % Rostad produkt avlagsnad via Den Ma fasens djup i rostugnen cin Cirkula- tionshas- tighet kg/tim Forhallande cirkulation: matning Sidout- lopps- SeparaOppning tor 14 17 68 760 10,6 0,09 0,751 49 66 408 6 68 870 12,4 0,03 0,34 74 26 79 500 7 104 813,0 1,6 0,0,noll 100 22622 1813,0 0,17 0,38 34 66 9060 60 Per att visa de fordelar, som uppnas genom uppfinningen, utfordes andra forsok, i vilka inga fasta partiklar aterfOrdes till rostningszonen. Foljande resultat erhollos: Sulfidmat- ningshas- Rostning tighet Temp. °C kg/tim Rostad % Sulfidsvavel produkt % totalt svavel % Rostad produkt avlagsnad via Sidout-loppstipp-ning 17 Den tkta fasens djup i rostugaen em Girkula-tionshas-tighet kg/tim Avloppsgas % SO,%O, Separator 14 68 812,12,0,54 1,86 14 41 noll 68 870 11,03,0,44 0,80 81 19 41 noll 1outforbart Sam ett annat exempel pa de ovanligt ld.ga sulfidsvavelhalter, som kunna uppnas i enligt foreliggande uppfinning rostade material, utfordes forsek med mattlig matningshastighet vid rost ning av ett likadant finfordelat pyrrotitkoncentrat diameter av 2,25 m. Resultaten angives nedan: Sulfid mat-ningshastig-het ton/dag Rostning Avloppsgas Temp. °CSO2 Rostad produkt % sulfid-% totalt svavelsvavel Approx. % Rostad produkt avlagsnad via Sidoutlopps- Separaoppning 17 tor 14 Forhallande cirkulation: matning 12-13 12-13 11-12 0,80 0,18 70 >0,712 21,3870 31,890 25,90 0,04 0,07 >0,0 Det inses att svavlet avlagsnades i anmarkningsvart hog grad. A finely divided pyrrotite concentrate containing 36% sulfur and about 5% silicate gait was fed into chamber 2, which had an inside diameter of 60 cm and was preheated to a temperature of Over ° C. The dense phase lick is formed to varying heights. Air in an amount which theoretically exceeds the amount required to burn the pyrrotite to Fe 2 O 3 and SO 2 was introduced through the tube 5. The results obtained in this way are given in the following table: Sulfide Rost feed flap speed Temp, kg / h • ° C Waste gas% SO,,% O, Roasted product% food% total sulfur sulfur% Roasted product removed via The depth of the Ma phase in the roasting furnace cin Circulation speed kg / h Relative circulation: feed Side outlet SeparaOpening tor 14 17 68 760 10.6 0.09 0.751 49 66 408 6 68 870 12.4 0.03 0.34 74 26 79 500 7 104 813.0 1.6 0.0, zero 100 22622 1813.0 0.17 To demonstrate the benefits achieved by the invention, other experiments are challenged in which no solid particles were returned to the roasting zone. The following results were obtained: Sulfide feed rate- Roasting rate Temp. ° C kg / h Roasted% Sulphide sulfur product% total sulfur% Roasted product deposited via Sidout flue tipping 17 Depth of the thick phase in the roasting hut em Girculation rate kg / h Sewage gas% SO,% O, Separator 14 68 812, 12,0,54 1,86 14 41 zero 68 870 11,03,0,44 0,80 81 19 41 zero 1forforable As another example of the unusually low sulphide sulfur contents which can be obtained in materials roasted according to the present invention, is attempted at a slow feed rate when roasting a similarly finely divided pyrrotite concentrate diameter of 2.25 m. The results are given below: Sulphide feed rate ton / day Roasting Sewage gas Temp. ° CSO2 Rusted product% sulphide-% total sulfur sulfur Approx. % Rusted product removed via Side outlet- Separate opening 17 Thu 14 Conditioning circulation: feed 12-13 12-13 11-12 0.80 0.18 70> 0.712 21.3870 31.890 25.90 0.04 0.07> 0.0 It is understood that the sulfur was deposited to a remarkably high degree.

Avloppsgaserna blir rika pa svaveldioxid som ken utvinnas. Nar svaveldioxiden skall utvinnas bor sa.mmansattningen av den oxiderande gasen regleras sa, att avloppsgaserna innehalla foga eller inget syre. — — The waste gases become rich in sulfur dioxide, which is extracted. When the sulfur dioxide is to be recovered, the composition of the oxidizing gas should be regulated so that the waste gases contain no or no oxygen. - -

Claims

Patent claim:

Roasting process, in which solid particles of a metal sulphide are continuously fed into a furnace and then roasted in a fluidized gas. Add in a stream of oxidizing gas to form a roasting product, particles of the roasting product are continuously removed in an amount equivalent to the amount of continuous feed, then unroasted sulphide, and the velocity of the gas stream being such that it frail at the beginning away from particles, some of which are returned to the bath, characterized by the drive, separating the particles of the gas stream from the bath away from the gas stream and back into them. such quantity per unit of time, that the weight ratio between the solid particles separated from the gas stream and returned to the bath and the unroasted sulphicle fed into the bath during the same time is higher than 1: 1. 2. Procedure according to patent claim 1, can be drawn ddrav, aft a part of or the whole roasting product is separated from the gas stream, which removes the particles which are returned to the bath. 3. A method according to claim 1, characterized in that part or all of the roasting product is separated from another part of the gas stream in Iran from which the particles which are athered into the bath are separated. 4. A loser according to claim 2 may draw a part, that part or all of the roasting product is separated from the gas stream inside the furnace under the influence of its weight and diverted through one or more side openings in the roasting furnace (wader the fluidized bed). any of patent claims 2-4, characterized in that the oxidizing gas is caused to flow through the roasting furnace at such a speed that the gas velocity in the upper part of the furnace above the fluidized bath is between 45 and 150 cm / sec. any of the foregoing patent claims, can be drawn, because the said weight ratio is chosen to be greater than 10: 1.

2. A process according to any one of the preceding patent claims, applied to the roasting of ferrous sulphide, characterized in that the ferrous sulphide is in the form of a pyrrotite concentrate with such a particle size that no more than 10% is retained on it. 200 mesh screen (B.S.S.). Request publications: Patents Iran USA Re 21 526, 2 343 780. Other publications: Chemie-Ingenieur-Technik 24 (1952): No. 2, p. 106. Stockholm 196

3. Itungl. Boktr. P. A. Norstedt & Sdner. 630009