EP0641864A1 - Process for roasting refractory gold ores - Google Patents
Process for roasting refractory gold ores Download PDFInfo
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- EP0641864A1 EP0641864A1 EP94202265A EP94202265A EP0641864A1 EP 0641864 A1 EP0641864 A1 EP 0641864A1 EP 94202265 A EP94202265 A EP 94202265A EP 94202265 A EP94202265 A EP 94202265A EP 0641864 A1 EP0641864 A1 EP 0641864A1
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- European Patent Office
- Prior art keywords
- fluidized bed
- roasting
- process according
- gas
- sulfur
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B1/00—Preliminary treatment of ores or scrap
- C22B1/02—Roasting processes
- C22B1/06—Sulfating roasting
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B1/00—Preliminary treatment of ores or scrap
- C22B1/02—Roasting processes
- C22B1/10—Roasting processes in fluidised form
Definitions
- the invention relates to a method for roasting refractory gold ores in an oxidizing atmosphere in a fluidized bed with the addition of fuels.
- Refractory gold ores are ores that cannot be leached directly with NaCN and contain arsenopyrites or pyrites with more or less organic carbon as gold carriers. They have a relatively low gold content. For such ores, the most complete possible oxidation of the sulfur and carbon content is required before the cyanide leaching. This oxidation takes place by roasting with oxygen-containing gases. For many refractory gold ores, the arsenopyrite, pyrite and organic carbon content is insufficient to produce the required heat of reaction and fuel must be added. A large number of refractory gold ores must be roasted at a relatively low temperature in order to achieve good gold yield during the subsequent leaching.
- Gold ores require gentle roasting to avoid heating up the particle surface.
- the gold yield is i.a. strongly dependent on the roasting temperature.
- the roasting temperature must be kept below the sintering temperature of the components of the respective ore.
- the invention has for its object to use a fuel that ignites reliably at low temperatures and in the combustion of which no or low proportions of CO, H2 and hydrocarbons are present in the exhaust gas.
- the object is achieved according to the invention in the process mentioned at the outset by adding sulfur and / or pyrite as fuel to the fluidized bed and by roasting at temperatures of 400 to 650 ° C. while supplying oxygen-containing gases.
- the advantage of the method according to the invention is that CO, H2 and hydrocarbons are not formed during the combustion of sulfur and / or pyrite.
- Sulfur and pyrite are surprisingly reliable at low roasting temperatures. Sulfur burns in the temperature range from 200 to 300 ° C, pyrite burns in the temperature range from 450 to 600 ° C.
- the sulfur and / or pyrite can be added by prior mixing with the gold ore or directly into the fluidized bed.
- refractory gold ores are roasted in a classic or in a circulating fluidized bed.
- the oxygen-containing gases are introduced as fluidizing gas into the fluidized bed below the bottom of the nozzle.
- oxygen-containing gases can additionally be introduced laterally into the fluidized bed reactor as primary and secondary gas.
- the oxygen-containing gases are air or oxygen-enriched air.
- a preferred embodiment is that the roasting takes place at temperatures of 500 to 550 ° C. Particularly good gold yields are achieved at these temperatures.
- a preferred embodiment of the invention is that the fuel is sulfur and / or pyrite and at least one additional fuel selected from hydrocarbons with a C atom number of 1 to 16, alcohols with a C atom number from 1 to 6 and an OH group number of 1 to 2, organic ethers with a C atom number of 2 to 8 and an O atom number of 1, CS2 or H2S are added to the fluidized bed.
- the ignition temperature of these fuels is reduced if the ignition temperature of these additional fuels is higher than the ignition temperature of sulfur or pyrite. This means that they are faster in such a mixture ignite and burn more easily. If the ignition temperature of one of these additional fuels is lower than the ignition temperature of sulfur or pyrite, the ignition temperature of sulfur or pyrite in a mixture with such an additional fuel is reduced.
- the concentration of the additional fuels must be higher than the concentration for the lower ignition limit of these fuels.
- the lower ignition limit of a fuel means the minimum concentration with which a fuel must be present in the gas mixture so that the fuel is still ignited.
- the additional fuels are added above their ignition limit if the heat content in the reactor is not sufficient to achieve the required roasting temperature.
- the heat content in the reactor is given by the amounts of carbon and sulfur present in refractory gold ores and by the amount of sulfur and / or pyrite added as fuel.
- the roasting temperature can thus be controlled by metering the additional fuels.
- the additional fuels are added in such quantities that the roasting temperature does not exceed 650 ° C, preferably 550 ° C, and the exhaust gas from the fluidized bed has an H2 content of ⁇ 10 vppm, preferably ⁇ 5 vppm, a CO content of ⁇ 0 , 1 vol .-%, preferably ⁇ 100 vppm, and a hydrocarbon content of ⁇ 100 vppm, preferably ⁇ 50 vppm.
- hydrocarbon mixtures are used as additional Fuels also use alcohol mixtures that are produced as waste products in the distillation of ethanol.
- a preferred embodiment of the invention is that the grain size of the gold ore is less than 1 mm. This grain size gives good results.
- a preferred embodiment of the invention is that 60 to 80% of the gold ore have a grain size below 75 microns. This grain size gives particularly good results.
- the term "grain size” stands for the mean grain diameter d50.
- a preferred embodiment of the invention is that the O2 content in the gas which is introduced into the fluidized bed is 20 to 50 vol .-%.
- the oxygen-enriched air results in a better ignition of the fuel mixture.
- the use of oxygen-enriched air is particularly economical.
- the advantage of using the additional fuels is that they largely burn at low temperature, the proportions of CO, H2 and hydrocarbons in the exhaust gas are very low and therefore do not need to be removed from the exhaust gas by post-combustion. In a subsequent sulfuric acid production, it is favorable that the proportions of CO, H2 and hydrocarbons are very low, since these substances act as catalyst poisons in the oxidation of SO2 to SO3.
- a preferred embodiment of the invention is that a partial flow of the exhaust gas is branched off after the dedusting of the hot exhaust gas and is mixed with the fluidizing gas before it is introduced into the fluidized bed.
- the fluidizing gas is heated up.
- an enrichment of SO2 is obtained in the exhaust gas.
- a preferred embodiment of the invention is that the SO2 gas formed during the roasting of refractory gold ores and discharged in the exhaust gas is fed to the production of sulfuric acid.
- the inventive method is also economical in that the SO2 gas formed during the roasting and discharged with the exhaust gas can be supplied to the sulfuric acid production without afterburning.
- a gas scrubber is provided before the SO2 gas is introduced into the sulfuric acid production plant.
- a preferred embodiment of the invention is that the roasting takes place in a circulating fluidized bed.
- the system of the circulating fluidized bed consists of the fluidized bed reactor, the return cyclone and the return line.
- This fluidized bed principle is characterized in that, in contrast to the "classic" fluidized bed, in which a dense phase is separated from the gas space above by a clear density jump, there are distribution states without a defined boundary layer. A leap in density between the dense phase and the dust space above is not present, but within the reactor the solids concentration decreases continuously from bottom to top. A gas-solid suspension is discharged from the upper part of the reactor.
- a refractory gold ore with a gold content of 8 g / t and 1.8% by weight of sulfur, which was present as pyrite, and 0.08% by weight of carbon was used.
- the roasting plant was a circulating fluidized bed plant, mainly consisting of the fluidized bed reactor, a recycle cyclone, which was connected directly to the gas outlet at the top of the reactor, and a recycle line. The solid separated in the cyclone was returned to the reactor via the return line.
- a mixture of 48 g pyrite per kg ore was produced. Then 40 kg / h of the mixture produced were fed into the fluidized bed reactor via a downpipe.
- Nm3 / h of air with 21 vol .-% O2 were introduced at a temperature of 400 ° C.
- the carrier gas flowed through the openings of the inflow floor.
- the temperature in the reactor was 520 ° C.
- the roasting gas had a content of 3.3 vol .-% SO2, 0.2 vol .-% CO2, 20 vppm CO and 16.3 vol .-% O2.
- the levels of H2 and hydrocarbons were below the detection limit of 1 vppm.
- the SO2-free exhaust gas was passed into the chimney.
- the roasted material had a sulfur content of ⁇ 0.05% by weight and a carbon content of ⁇ 0.01% by weight.
- a gold yield of 94% was achieved during further processing.
- Example 2 was carried out as Example 1, with the difference that the carrier gas contained 32% by volume of O2 and 7% by volume of SO2 by recirculated exhaust gas.
- a mixture containing 50 g of sulfur per kg of ore was introduced into the fluidized bed reactor.
- the roasting gas had a content of 12.7 vol .-% SO2, 0.1 vol .-% CO2, 5 vppm CO and 24.2 vol .-% O2.
- the levels of H2 and hydrocarbons were below the detection limit of 1 vppm.
- the roasted material had a sulfur content of ⁇ 0.04% by weight and a carbon content of ⁇ 0.01% by weight.
- a gold yield of 96% was achieved during further processing.
- the gold ore used in Examples 1 and 2 had the following composition: 8 g / t Au 3.3% by weight FeS2 0.07 wt% Fe [AsS]
- the pyrite used in Example 1 had the following composition: 91% by weight FeS2 2 wt% FeS 7 wt .-% SiO2, Al2O3 and other ingredients
- the sulfur used in Example 2 had the following composition: 98% by weight S 2% by weight impurity
Abstract
Description
Die Erfindung betrifft ein Verfahren zum Rösten refraktärer Golderze in oxidierender Atmosphäre in einer Wirbelschicht unter Zusatz von Brennstoffen.The invention relates to a method for roasting refractory gold ores in an oxidizing atmosphere in a fluidized bed with the addition of fuels.
Refraktäre Golderze sind solche Erze, die sich nicht direkt mit NaCN laugen lassen und als Goldträger Arsenopyrite oder Pyrite mit mehr oder weniger organischem Kohlenstoff enthalten. Sie haben einen relativ niedrigen Goldgehalt. Für solche Erze ist vor der Cyanidlaugung eine möglichst vollständige Oxidation des Schwefel- und Kohlenstoffgehaltes erforderlich. Diese Oxidation erfolgt durch Röstung mit sauerstoffhaltigen Gasen. Bei vielen refraktären Golderzen reicht der vorhandene Gehalt an Arsenopyrit, Pyrit und organischem Kohlenstoff nicht zur Erzeugung der erforderlichen Reaktionswärme aus, und es muß Brennstoff zugesetzt werden. Eine Vielzahl von refraktären Golderzen muß bei relativ niedriger Temperatur geröstet werden, damit ein gutes Goldausbringen bei der anschließenden Laugung erzielt wird.Refractory gold ores are ores that cannot be leached directly with NaCN and contain arsenopyrites or pyrites with more or less organic carbon as gold carriers. They have a relatively low gold content. For such ores, the most complete possible oxidation of the sulfur and carbon content is required before the cyanide leaching. This oxidation takes place by roasting with oxygen-containing gases. For many refractory gold ores, the arsenopyrite, pyrite and organic carbon content is insufficient to produce the required heat of reaction and fuel must be added. A large number of refractory gold ores must be roasted at a relatively low temperature in order to achieve good gold yield during the subsequent leaching.
Aus der EP-A-0 508 542 ist bekannt, daß Golderze bei einer Temperatur von 475 bis 600°C und insbesondere bei 500 bis 575°C gerostet werden sollen. Als Brennstoffzusatz werden Kohle, Butan oder Propan genannt. Die Zündtemperatur soll dem des Propans entsprechen oder niedriger liegen. Propan und Butan werden jedoch nur zu einem unbefriedigenden Teil zu CO₂ und H₂O verbrannt. Bei der Verbrennung entstehen erhebliche Mengen an CO mit einer Zündtemperatur von 600 bis 650°C und H₂ mit einer Zündtemperatur von 560 bis 580°C.From EP-A-0 508 542 it is known that gold ores are to be rusted at a temperature of 475 to 600 ° C and in particular at 500 to 575 ° C. Coal, butane or propane are mentioned as fuel additives. The ignition temperature should be the same as or lower than that of propane. However, propane and butane are only burned to an unsatisfactory extent to CO₂ and H₂O. The combustion produces significant amounts of CO with an ignition temperature of 600 to 650 ° C and H₂ with an ignition temperature of 560 to 580 ° C.
Golderze erfordern eine schonende Röstung, um Erhitzungen an der Partikeloberfläche zu vermeiden. Die Goldausbeute ist u.a. stark von der Rösttemperatur abhängig. Die Rösttemperatur muß unterhalb der Versinterungstemperatur der Bestandteile des jeweiligen Erzes gehalten werden.Gold ores require gentle roasting to avoid heating up the particle surface. The gold yield is i.a. strongly dependent on the roasting temperature. The roasting temperature must be kept below the sintering temperature of the components of the respective ore.
Die meisten Golderze weisen niedrige Anteile an Pyrit und/oder anorganischem Kohlenstoff auf. Bedingt durch Wärmeverluste, die beim Aufheizen entstehen, durch Abgasverluste sowie Austragsverluste und dergleichen reicht der im Golderz enthaltene Heizwert nicht aus, um eine autotherme Röstung selbst bei Temperaturen von etwa nur 500°C durchzuführen. Daher ist der Einsatz von zusätzlichem Brennstoff mit einer niedrigen Zünd- und Verbrennungtemperatur erforderlich, um die Goldausbeute nicht zu verringern.Most gold ores have low levels of pyrite and / or inorganic carbon. Due to heat losses that occur during heating up, exhaust gas losses as well as discharge losses and the like, the calorific value contained in the gold ore is not sufficient to carry out an autothermal roasting even at temperatures of only about 500 ° C. It is therefore necessary to use additional fuel with a low ignition and combustion temperature in order not to reduce the gold yield.
Der Erfindung liegt die Aufgabe zugrunde, einen Brennstoff einzusetzen, der bei niedrigen Temperaturen zuverlässig zündet und bei dessen Verbrennung keine oder niedrige Anteile an CO, H₂ und Kohlenwasserstoffen im Abgas vorhanden sind.The invention has for its object to use a fuel that ignites reliably at low temperatures and in the combustion of which no or low proportions of CO, H₂ and hydrocarbons are present in the exhaust gas.
Die Lösung der Aufgabe erfolgt erfindungsgemäß bei dem eingangs genannten Verfahren dadurch, daß als Brennstoff Schwefel und/oder Pyrit in die Wirbelschicht zugegeben werden und die Röstung bei Temperaturen von 400 bis 650°C unter Zufuhr von sauerstoffhaltigen Gasen erfolgt. Der Vorteil des erfindungsgemäßen Verfahrens liegt darin, daß CO, H₂ und Kohlenwasserstoffe bei der Verbrennung von Schwefel und/oder Pyrit nicht gebildet werden.The object is achieved according to the invention in the process mentioned at the outset by adding sulfur and / or pyrite as fuel to the fluidized bed and by roasting at temperatures of 400 to 650 ° C. while supplying oxygen-containing gases. The advantage of the method according to the invention is that CO, H₂ and hydrocarbons are not formed during the combustion of sulfur and / or pyrite.
Schwefel und Pyrit zeigen eine überraschend zuverlässige Zündbereitschaft bei niedrigen Rösttemperaturen. Schwefel brennt im Temperaturbereich von 200 bis 300°C, Pyrit brennt im Temperaturbereich von 450 bis 600°C. Die Zugabe von Schwefel und/oder Pyrit kann durch vorherige Mischung mit dem Golderz oder direkt in die Wirbelschicht erfolgen.Sulfur and pyrite are surprisingly reliable at low roasting temperatures. Sulfur burns in the temperature range from 200 to 300 ° C, pyrite burns in the temperature range from 450 to 600 ° C. The sulfur and / or pyrite can be added by prior mixing with the gold ore or directly into the fluidized bed.
Die Röstung refraktärer Golderze erfolgt erfindungsgemäß in einer klassischen oder in einer zirkulierenden Wirbelschicht. Die sauerstoffhaltigen Gase werden als Fluidisierungsgas unterhalb des Düsenbodens in die Wirbelschicht eingeleitet. Erfindungsgemäß ist vorgesehen, daß sauerstoffhaltige Gase zusätzlich als Primär- und Sekundärgas seitlich in den Wirbelschichtreaktor eingeleitet werden können. Die sauerstoffhaltigen Gase sind Luft oder sauerstoffangereicherte Luft.According to the invention, refractory gold ores are roasted in a classic or in a circulating fluidized bed. The oxygen-containing gases are introduced as fluidizing gas into the fluidized bed below the bottom of the nozzle. According to the invention it is provided that oxygen-containing gases can additionally be introduced laterally into the fluidized bed reactor as primary and secondary gas. The oxygen-containing gases are air or oxygen-enriched air.
Eine bevorzugte Ausgestaltung besteht darin, daß die Röstung bei Temperaturen von 500 bis 550°C erfolgt. Bei diesen Temperaturen werden besonders gute Goldausbeuten erzielt.A preferred embodiment is that the roasting takes place at temperatures of 500 to 550 ° C. Particularly good gold yields are achieved at these temperatures.
Eine bevorzugte Ausgestaltung der Erfindung besteht darin, daß als Brennstoff Schwefel und/oder Pyrit und mindestens ein zusätzlicher Brennstoff, ausgewählt aus Kohlenwasserstoffen mit einer C-Atomzahl von 1 bis 16, Alkoholen mit einer C-Atomzahl von 1 bis 6 und einer OH-Gruppenzahl von 1 bis 2, organischen Äthern mit einer C-Atomzahl von 2 bis 8 und einer O-Atomzahl von 1, CS₂ oder H₂S in die Wirbelschicht zugegeben werden. Durch das gemeinsame Verbrennen von Schwefel und/oder Pyrit mit einem oder mehreren dieser zusätzlichen Brennstoffe wird die Zündtemperatur dieser Brennstoffe herabgesetzt, wenn die Zündtemperatur dieser zusätzlichen Brennstoffe höher liegt als die Zündtemperatur von Schwefel oder Pyrit. Das bedeutet, daß sie in einem solchen Gemisch schneller zünden und leichter verbrennen. Liegt die Zündtemperatur eines dieser zusätzlichen Brennstoffe niedriger als die Zündtemperatur von Schwefel oder Pyrit, so wird die Zündtemperatur von Schwefel oder Pyrit im Gemisch mit einem solchen zusätzlichen Brennstoff herabgesetzt.A preferred embodiment of the invention is that the fuel is sulfur and / or pyrite and at least one additional fuel selected from hydrocarbons with a C atom number of 1 to 16, alcohols with a C atom number from 1 to 6 and an OH group number of 1 to 2, organic ethers with a C atom number of 2 to 8 and an O atom number of 1, CS₂ or H₂S are added to the fluidized bed. By burning sulfur and / or pyrite together with one or more of these additional fuels, the ignition temperature of these fuels is reduced if the ignition temperature of these additional fuels is higher than the ignition temperature of sulfur or pyrite. This means that they are faster in such a mixture ignite and burn more easily. If the ignition temperature of one of these additional fuels is lower than the ignition temperature of sulfur or pyrite, the ignition temperature of sulfur or pyrite in a mixture with such an additional fuel is reduced.
Im Gemisch mit Schwefel und/oder Pyrit muß die Konzentration der zusätzlichen Brennstoffe höher liegen als die Konzentration für die untere Zündgrenze dieser Brennstoffe. Die untere Zündgrenze eines Brennstoffes bedeutet die Mindestkonzentration, mit der ein Brennstoff im Gasgemisch vorliegen muß, damit noch eine Zündung des Brennstoffes erfolgt. Die zusätzlichen Brennstoffe werden oberhalb ihrer Zündgrenze zugegeben, wenn der Wärmeinhalt im Reaktor nicht ausreicht, um die erforderliche Rösttemperatur zu erreichen. Der Wärmeinhalt im Reaktor ist gegeben durch die in refraktären Golderzen vorhandenen Mengen an Kohlenstoff und Schwefel und durch die Menge des als Brennstoff zugegebenen Schwefels und/oder Pyrits. Die Rösttemperatur kann somit durch Dosierung der zusätzlichen Brennstoffe gesteuert werden. Die zusätzlichen Brennstoffe werden in solchen Mengen zugegeben, daß die Rösttemperatur 650°C, vorzugsweise 550°C, nicht übersteigt und das Abgas aus der Wirbelschicht einen H₂-Gehalt von < 10 vppm, vorzugsweise < 5 vppm, einen CO-Gehalt von < 0,1 Vol.-%, vorzugsweise < 100 vppm, und einen Kohlenwasserstoffgehalt von < 100 vppm, vorzugsweise < 50 vppm, aufweist.In a mixture with sulfur and / or pyrite, the concentration of the additional fuels must be higher than the concentration for the lower ignition limit of these fuels. The lower ignition limit of a fuel means the minimum concentration with which a fuel must be present in the gas mixture so that the fuel is still ignited. The additional fuels are added above their ignition limit if the heat content in the reactor is not sufficient to achieve the required roasting temperature. The heat content in the reactor is given by the amounts of carbon and sulfur present in refractory gold ores and by the amount of sulfur and / or pyrite added as fuel. The roasting temperature can thus be controlled by metering the additional fuels. The additional fuels are added in such quantities that the roasting temperature does not exceed 650 ° C, preferably 550 ° C, and the exhaust gas from the fluidized bed has an H₂ content of <10 vppm, preferably <5 vppm, a CO content of <0 , 1 vol .-%, preferably <100 vppm, and a hydrocarbon content of <100 vppm, preferably <50 vppm.
Als zusätzliche Brennstoffe werden Kohlenwasserstoffgemische, die als Destillationsfraktionen, wie z.B. Kerosin usw. oder Raffinerie-Abfallprodukte anfallen, verwendet. Neben Kohlenwasserstoffgemischen werden als zusätzliche Brennstoffe auch Alkoholgemische, die bei der Destillation von Äthanol als Abfallprodukte anfallen, verwendet.Hydrocarbon mixtures which are obtained as distillation fractions, such as kerosene etc. or refinery waste products, are used as additional fuels. In addition to hydrocarbon mixtures are used as additional Fuels also use alcohol mixtures that are produced as waste products in the distillation of ethanol.
Eine bevorzugte Ausgestaltung der Erfindung besteht darin, daß die Korngröße des Golderzes unter 1 mm liegt. Diese Korngröße ergibt gute Ergebnisse.A preferred embodiment of the invention is that the grain size of the gold ore is less than 1 mm. This grain size gives good results.
Eine bevorzugte Ausgestaltung der Erfindung besteht darin, daß 60 bis 80 % des Golderzes eine Korngröße unter 75 µm aufweisen. Diese Korngröße ergibt besonders gute Ergebnisse. Der Begriff "Korngröße" steht für den mittleren Korndurchmesser d₅₀.A preferred embodiment of the invention is that 60 to 80% of the gold ore have a grain size below 75 microns. This grain size gives particularly good results. The term "grain size" stands for the mean grain diameter d₅₀.
Eine bevorzugte Ausgestaltung der Erfindung besteht darin, daß der O₂-Gehalt in dem Gas, das in die Wirbelschicht eingeleitet wird, 20 bis 50 Vol.-% beträgt. Die sauerstoffangereicherte Luft ergibt eine bessere Zündung des Brennstoffgemisches. Die Verwendung der sauerstoffangereicherten Luft ist besonders wirtschaftlich.A preferred embodiment of the invention is that the O₂ content in the gas which is introduced into the fluidized bed is 20 to 50 vol .-%. The oxygen-enriched air results in a better ignition of the fuel mixture. The use of oxygen-enriched air is particularly economical.
Der Vorteil des Einsatzes der zusätzlichen Brennstoffe liegt darin, daß sie bei niedriger Temperatur weitgehend verbrennen, die Anteile an CO, H₂ und Kohlenwasserstoffen im Abgas sehr niedrig sind und daher nicht durch Nachverbrennung aus dem Abgas entfernt zu werden brauchen. Bei einer nachfolgenden Schwefelsäure-Herstellung ist es günstig, daß die Anteile an CO, H₂ und Kohlenwasserstoffen sehr niedrig sind, da diese Stoffe bei der Oxidation von SO₂ zu SO₃ als Katalysatorgifte wirken.The advantage of using the additional fuels is that they largely burn at low temperature, the proportions of CO, H₂ and hydrocarbons in the exhaust gas are very low and therefore do not need to be removed from the exhaust gas by post-combustion. In a subsequent sulfuric acid production, it is favorable that the proportions of CO, H₂ and hydrocarbons are very low, since these substances act as catalyst poisons in the oxidation of SO₂ to SO₃.
Eine bevorzugte Ausgestaltung der Erfindung besteht darin, daß ein Teilstrom des Abgases nach der Entstaubung des heißen Abgases abgezweigt wird und dem Fluidisierungsgas vor der Einleitung in die Wirbelschicht zugemischt wird. Durch die Rückführung eines Teils des Abgases und Vermischen mit dem Fluidisierungsgas wird erreicht, daß das Fluidisierungsgas aufgewärmt wird. Durch die Kreislaufführung eines Teils des Abgases wird eine Anreicherung von SO₂ im Abgas erhalten.A preferred embodiment of the invention is that a partial flow of the exhaust gas is branched off after the dedusting of the hot exhaust gas and is mixed with the fluidizing gas before it is introduced into the fluidized bed. By recycling part of the exhaust gas and mixing it with the fluidizing gas, the fluidizing gas is heated up. By recycling part of the exhaust gas, an enrichment of SO₂ is obtained in the exhaust gas.
Eine bevorzugte Ausgestaltung der Erfindung besteht darin, daß das beim Rösten refraktärer Golderze gebildete und im Abgas abgeführte SO₂-Gas der Schwefelsäure-Herstellung zugeführt wird. Das erfindungsgemäße Verfahren wird dadurch zusätzlich wirtschaftlich, daß das bei der Röstung gebildete und mit dem Abgas abgeführte SO₂-Gas ohne Nachverbrennung der Schwefelsäure-Herstellung zugeführt werden kann. Es ist vor der Einleitung des SO₂-Gases in die Schwefelsäure-Herstellungsanlage eine Gaswäsche vorgesehen.A preferred embodiment of the invention is that the SO2 gas formed during the roasting of refractory gold ores and discharged in the exhaust gas is fed to the production of sulfuric acid. The inventive method is also economical in that the SO₂ gas formed during the roasting and discharged with the exhaust gas can be supplied to the sulfuric acid production without afterburning. A gas scrubber is provided before the SO₂ gas is introduced into the sulfuric acid production plant.
Eine bevorzugte Ausgestaltung der Erfindung besteht darin, daß die Röstung in einer zirkulierenden Wirbelschicht erfolgt.A preferred embodiment of the invention is that the roasting takes place in a circulating fluidized bed.
Das System der zirkulierenden Wirbelschicht besteht aus dem Wirbelschichtreaktor, dem Rückführzyklon und der Rückführleitung. Dieses Wirbelschichtprinzip zeichnet sich dadurch aus, daß im Unterschied zur "klassischen" Wirbelschicht, bei der eine dichte Phase durch einen deutlichen Dichtesprung von dem darüber befindlichen Gasraum getrennt ist, Verteilungszustände ohne definierte Grenzschicht vorliegen. Ein Dichtesprung zwischen dichter Phase und darüber befindlichem Staubraum ist nicht vorhanden, jedoch nimmt innerhalb des Reaktors die Feststoffkonzentration von unten nach oben ständig ab. Aus dem oberen Teil des Reaktors wird eine Gas-Feststoff-Suspension ausgetragen. Bei der Definition der Betriebsbedingungen über die Kennzahlen von Froude und Archimedes ergeben sich die Bereiche:
bzw.
wobei
sind.The system of the circulating fluidized bed consists of the fluidized bed reactor, the return cyclone and the return line. This fluidized bed principle is characterized in that, in contrast to the "classic" fluidized bed, in which a dense phase is separated from the gas space above by a clear density jump, there are distribution states without a defined boundary layer. A leap in density between the dense phase and the dust space above is not present, but within the reactor the solids concentration decreases continuously from bottom to top. A gas-solid suspension is discharged from the upper part of the reactor. When defining the operating conditions using the key figures from Froude and Archimedes, the following areas result:
respectively.
in which
are.
Es bedeuten:
- u
- die relative Gasgeschwindigkeit in m/sec.
- Ar
- die Archimedes-Zahl
- Fr
- die Froude-Zahl
- ρg
- die Dichte des Gases in kg/m³
- ρk
- die Dichte des Feststoffteilchens in kg/m³
- dk
- den Durchmesser des kugelförmigen Teilchens in m
- ν
- die kinematische Zähigkeit in m²/sec.
- g
- die Gravitationskonstante in m/sec.²
Die aus dem Wirbelschichtreaktor ausgetragene Suspension wird in den Rückführzyklon der zirkulierenden Wirbelschicht geleitet, dort weitgehend vom Feststoff befreit, und der abgeschiedene Feststoff wird derart in den Wirbelschichtreaktor zurückgeleitet, daß innerhalb der zirkulierenden Wirbelschicht der stündliche Feststoffumlauf mindestens das Vierfache des im Wirbelschichtreaktor befindlichen Feststoffgewichtes beträgt.It means:
- u
- the relative gas velocity in m / sec.
- Ar
- the Archimedes number
- Fr
- the Froude number
- ρg
- the density of the gas in kg / m³
- ρk
- the density of the solid particle in kg / m³
- d k
- the diameter of the spherical particle in m
- ν
- the kinematic toughness in m² / sec.
- G
- the gravitational constant in m / sec.²
The suspension discharged from the fluidized bed reactor is passed into the recycle cyclone of the circulating fluidized bed, largely freed from the solids there, and the separated solid is returned to the fluidized bed reactor in such a way that the hourly solids circulation within the circulating fluidized bed is at least four times the solids weight in the fluidized bed reactor.
Die Erfindung wird anhand der Beispiele erläutert.The invention is illustrated by the examples.
Es wurde ein refraktäres Golderz mit einem Goldgehalt von 8 g/t und 1,8 Gew.-% Schwefel, der als Pyrit vorlag, und 0,08 Gew.-% Kohlenstoff eingesetzt. Die Korngröße betrug d₅₀ = 30 µm und 100 % < 200 µm.A refractory gold ore with a gold content of 8 g / t and 1.8% by weight of sulfur, which was present as pyrite, and 0.08% by weight of carbon was used. The grain size was d₅₀ = 30 µm and 100% <200 µm.
Die Röstanlage war eine zirkulierende Wirbelschichtanlage, hauptsächlich bestehend aus dem Wirbelschichtreaktor, einem Rückführzyklon, der direkt an den Gasaustritt am Oberteil des Reaktors angeschlossen war, und einer Rückführleitung. Der im Zyklon abgeschiedene Feststoff wurde über die Rückführleitung in den Reaktor zurückgeführt.The roasting plant was a circulating fluidized bed plant, mainly consisting of the fluidized bed reactor, a recycle cyclone, which was connected directly to the gas outlet at the top of the reactor, and a recycle line. The solid separated in the cyclone was returned to the reactor via the return line.
Es wurde ein Gemisch aus 48 g Pyrit pro kg Erz hergestellt. Dann wurden 40 kg/h des hergestellten Gemisches über eine Falleitung in den Wirbelschichtreaktor aufgegeben.A mixture of 48 g pyrite per kg ore was produced. Then 40 kg / h of the mixture produced were fed into the fluidized bed reactor via a downpipe.
In den Windkasten des Wirbelschichtreaktors wurden 22 Nm³/h Luft mit 21 Vol.-% O₂ mit einer Temperatur von 400°C eingeleitet. Das Trägergas strömte durch die Öffnungen des Anströmbodens. Die Temperatur im Reaktor betrug 520°C. Das Röstgas hatte einen Gehalt von 3,3 Vol.-% SO₂, 0,2 Vol.-% CO₂, 20 vppm CO und 16,3 Vol.-% O₂. Die Gehalte an H₂ und Kohlenwasserstoffen lagen unterhalb der Nachweisgrenze von 1 vppm. Nach einer alkalischen Waschung des Abgases wurde das von SO₂ befreite Abgas in den Kamin geleitet. Das Röstgut hatte einen Schwefelgehalt von < 0,05 Gew.-% und einen Kohlenstoffgehalt von < 0,01 Gew.-%. Bei der Weiterverarbeitung wurde eine Goldausbeute von 94 % erzielt.In the wind box of the fluidized bed reactor 22 Nm³ / h of air with 21 vol .-% O₂ were introduced at a temperature of 400 ° C. The carrier gas flowed through the openings of the inflow floor. The temperature in the reactor was 520 ° C. The roasting gas had a content of 3.3 vol .-% SO₂, 0.2 vol .-% CO₂, 20 vppm CO and 16.3 vol .-% O₂. The levels of H₂ and hydrocarbons were below the detection limit of 1 vppm. After an alkaline scrubbing of the exhaust gas, the SO₂-free exhaust gas was passed into the chimney. The roasted material had a sulfur content of <0.05% by weight and a carbon content of <0.01% by weight. A gold yield of 94% was achieved during further processing.
Beispiel 2 wurde wie Beispiel 1 durchgeführt mit dem Unterschied, daß das Trägergas 32 Vol.-% O₂ und durch zurückgeführtes Abgas 7 Vol.-% SO₂ enthielt. In den Wirbelschichtreaktor wurde ein Gemisch aufgegeben, das 50 g Schwefel pro kg Erz enthielt. Das Röstgas hatte einen Gehalt von 12,7 Vol.-% SO₂, 0,1 Vol.-% CO₂, 5 vppm CO und 24,2 Vol.-% O₂. Die Gehalte an H₂ und Kohlenwasserstoffen lagen unterhalb der Nachweisgrenze von 1 vppm. Das Röstgut hatte einen Schwefelgehalt von < 0,04 Gew.-% und einen Kohlenstoffgehalt von < 0,01 Gew.-%. Bei der Weiterverarbeitung wurde eine Goldausbeute von 96 % erzielt.Example 2 was carried out as Example 1, with the difference that the carrier gas contained 32% by volume of O₂ and 7% by volume of SO₂ by recirculated exhaust gas. A mixture containing 50 g of sulfur per kg of ore was introduced into the fluidized bed reactor. The roasting gas had a content of 12.7 vol .-% SO₂, 0.1 vol .-% CO₂, 5 vppm CO and 24.2 vol .-% O₂. The levels of H₂ and hydrocarbons were below the detection limit of 1 vppm. The roasted material had a sulfur content of <0.04% by weight and a carbon content of <0.01% by weight. A gold yield of 96% was achieved during further processing.
Das in den Beispielen 1 und 2 verwendete Golderz hatte die folgende Zusammensetzung:
8 g/t Au
3,3 Gew.-% FeS₂
0,07 Gew.-% Fe[AsS]
Der im Beispiel 1 verwendete Pyrit hatte die folgende Zusammensetzung:
91 Gew.-% FeS₂
2 Gew.-% FeS
7 Gew.-% SiO₂, Al₂O₃ und restliche Bestandteile
Der im Beispiel 2 verwendete Schwefel hatte die folgende Zusammensetzung:
98 Gew.-% S
2 Gew.-% VerunreinigungThe gold ore used in Examples 1 and 2 had the following composition:
8 g / t Au
3.3% by weight FeS₂
0.07 wt% Fe [AsS]
The pyrite used in Example 1 had the following composition:
91% by weight FeS₂
2 wt% FeS
7 wt .-% SiO₂, Al₂O₃ and other ingredients
The sulfur used in Example 2 had the following composition:
98% by weight S
2% by weight impurity
Claims (9)
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE4329417 | 1993-09-01 | ||
| DE4329417A DE4329417C1 (en) | 1993-09-01 | 1993-09-01 | Process for roasting refractory gold ores |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| EP0641864A1 true EP0641864A1 (en) | 1995-03-08 |
| EP0641864B1 EP0641864B1 (en) | 1998-03-04 |
Family
ID=6496516
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP94202265A Expired - Lifetime EP0641864B1 (en) | 1993-09-01 | 1994-08-05 | Process for roasting refractory gold ores |
Country Status (6)
| Country | Link |
|---|---|
| EP (1) | EP0641864B1 (en) |
| AU (1) | AU672715B2 (en) |
| DE (2) | DE4329417C1 (en) |
| ES (1) | ES2113050T3 (en) |
| PE (1) | PE11195A1 (en) |
| ZA (1) | ZA946709B (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| RU2443790C1 (en) * | 2010-07-01 | 2012-02-27 | Открытое акционерное общество "Иркутский научно-исследовательский институт благородных и редких металлов и алмазов" ОАО "Иргиредмет" | Method for determining content of precious metals in ores and their derivatives |
| WO2014127808A1 (en) | 2013-02-20 | 2014-08-28 | Outotec (Finland) Oy | Process and plant for producing copper and/or cobalt sulfate |
Families Citing this family (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6482373B1 (en) | 1991-04-12 | 2002-11-19 | Newmont Usa Limited | Process for treating ore having recoverable metal values including arsenic containing components |
| DE4314231A1 (en) * | 1993-04-30 | 1994-11-03 | Metallgesellschaft Ag | Process for roasting refractory gold ores |
| DE19546538A1 (en) * | 1995-12-13 | 1997-06-19 | Metallgesellschaft Ag | Process for the thermal treatment of refractory gold ores |
| CA2263497A1 (en) * | 1996-08-27 | 1998-03-05 | Paul R. Kruesi | Method for microwave induced oxidation of sulphidic ore material in fluidized bed without sulphur dioxide emissions |
| US5972302A (en) * | 1996-08-27 | 1999-10-26 | Emr Microwave Technology Corporation | Method for the microwave induced oxidation of pyritic ores without the production of sulphur dioxide |
| AUPQ078399A0 (en) * | 1999-06-04 | 1999-06-24 | Tox Free Systems Limited | Recovery of gold from gold sulphides |
| EP1327693A1 (en) * | 2002-01-12 | 2003-07-16 | Alexander Beckmann | Process for extracting cobalt and nickel from ores and ore concentrates |
| CN1308471C (en) | 2001-09-14 | 2007-04-04 | 亚历山大·贝克曼 | Method for obtaining cobalt and nickel from ores and ore concentrates |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0501542A1 (en) * | 1991-02-09 | 1992-09-02 | METALLGESELLSCHAFT Aktiengesellschaft | Method for roasting refractory gold ores |
| EP0508542A2 (en) * | 1991-04-12 | 1992-10-14 | METALLGESELLSCHAFT Aktiengesellschaft | Process for treating ore having recoverable metal values including arsenic containing components |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5123956A (en) * | 1991-04-12 | 1992-06-23 | Newmont Mining Corporation | Process for treating ore having recoverable gold values and including arsenic-, carbon- and sulfur-containing components by roasting in an oxygen-enriched gaseous atmosphere |
-
1993
- 1993-09-01 DE DE4329417A patent/DE4329417C1/en not_active Expired - Lifetime
-
1994
- 1994-08-05 DE DE59405354T patent/DE59405354D1/en not_active Expired - Fee Related
- 1994-08-05 EP EP94202265A patent/EP0641864B1/en not_active Expired - Lifetime
- 1994-08-05 ES ES94202265T patent/ES2113050T3/en not_active Expired - Lifetime
- 1994-08-23 PE PE1994248998A patent/PE11195A1/en not_active IP Right Cessation
- 1994-08-30 AU AU71583/94A patent/AU672715B2/en not_active Expired
- 1994-09-01 ZA ZA946709A patent/ZA946709B/en unknown
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0501542A1 (en) * | 1991-02-09 | 1992-09-02 | METALLGESELLSCHAFT Aktiengesellschaft | Method for roasting refractory gold ores |
| EP0508542A2 (en) * | 1991-04-12 | 1992-10-14 | METALLGESELLSCHAFT Aktiengesellschaft | Process for treating ore having recoverable metal values including arsenic containing components |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| RU2443790C1 (en) * | 2010-07-01 | 2012-02-27 | Открытое акционерное общество "Иркутский научно-исследовательский институт благородных и редких металлов и алмазов" ОАО "Иргиредмет" | Method for determining content of precious metals in ores and their derivatives |
| WO2014127808A1 (en) | 2013-02-20 | 2014-08-28 | Outotec (Finland) Oy | Process and plant for producing copper and/or cobalt sulfate |
Also Published As
| Publication number | Publication date |
|---|---|
| PE11195A1 (en) | 1995-05-06 |
| ES2113050T3 (en) | 1998-04-16 |
| EP0641864B1 (en) | 1998-03-04 |
| DE59405354D1 (en) | 1998-04-09 |
| ZA946709B (en) | 1995-04-21 |
| AU7158394A (en) | 1995-03-16 |
| DE4329417C1 (en) | 1994-08-18 |
| AU672715B2 (en) | 1996-10-10 |
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