WO2015078493A1 - Grillage de concentrés d'oxydes métalliques pauvres en composés soufrés - Google Patents

Grillage de concentrés d'oxydes métalliques pauvres en composés soufrés Download PDF

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Publication number
WO2015078493A1
WO2015078493A1 PCT/EP2013/074831 EP2013074831W WO2015078493A1 WO 2015078493 A1 WO2015078493 A1 WO 2015078493A1 EP 2013074831 W EP2013074831 W EP 2013074831W WO 2015078493 A1 WO2015078493 A1 WO 2015078493A1
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WO
WIPO (PCT)
Prior art keywords
sulfur
metal oxide
concentrate
poor
gas
Prior art date
Application number
PCT/EP2013/074831
Other languages
English (en)
Inventor
Maija-Leena Metsärinta
Jussi Liipo
Marcus Runkel
Original Assignee
Outotec (Finland) Oy
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Outotec (Finland) Oy filed Critical Outotec (Finland) Oy
Priority to PCT/EP2013/074831 priority Critical patent/WO2015078493A1/fr
Priority to CA2930762A priority patent/CA2930762C/fr
Priority to AP2016009226A priority patent/AP2016009226A0/en
Publication of WO2015078493A1 publication Critical patent/WO2015078493A1/fr

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Classifications

    • 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
    • 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
    • C22B34/00—Obtaining refractory metals
    • C22B34/20—Obtaining niobium, tantalum or vanadium
    • C22B34/24—Obtaining niobium or tantalum
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/20—Recycling

Definitions

  • the present invention relates to pre-treatment of metal oxide concentrates, in particular concentrates with low sulfur content, and provides a method of pre-treating of sulfur-poor metal oxide concentrate for removing most or all the sulfur contained in the oxide concentrate.
  • Roasting is typically applied to concentrates such as sphalerite or pyrite having a high heat value which provides enough energy for the heating of the roasting step and even extra energy is produced.
  • this type of roasting is not possible for material with limited sulfur and carbon content.
  • the concentrate In order to recover scarce valuable metals from concentrates with low sulfur content the concentrate must be pre-treated to remove most or all the sulfur contained in the concentrate. This allows further processing of the concentrates in hydrometallurgical processes which do not tolerate the pres- ence of sulfur.
  • the invention is based on the idea of heating of oxide concentrates with limited sulfur content in presence of oxygen and an external fuel source which provides the energy required for oxidation and/or thermal composition of the sulfur. This is advantageously accomplished in a fluidized bed furnace, whereby the external fuel source provided by fuel lances.
  • Figure 1 shows a first predominance diagram for Fe-O-S systems
  • Figure 2 shows a second predominance diagram for Fe-O-S systems
  • Figure 3 illustrates a flow diagram of a first example of the method of the present invention.
  • the present invention relates to a method of pre-treating sulfur-poor metal oxide concentrate, comprising the steps of: (o) providing sulfur-poor metal oxide concentrate having sulfur content below 10 % w/w; (a) heating the sulfur-poor metal oxide concentrate at an elevated temperature and in pres- ence of oxygen and an external fuel source to oxidize sulfur compounds contained in the sulfur-poor metal oxide concentrate to corresponding oxides and/or to thermally decompose the said sulfur compounds to obtain a sulfur- depleted metal oxide calcine and a sulfur-containing off-gas; and (b) separating the sulfur-depleted metal oxide calcine from the sulfur-containing off-gas; (c) cooling the obtained sulfur-depleted oxide calcine; (d) cooling the off-gas by quenching; and (e) scrubbing the cooled off-gas to recover sulfur.
  • the heating step (a) can be performed in any roaster found suitable by a person skilled in the art.
  • the roasting step (a) can for example be carried out in a roaster selected from the group consisting of a rotary kiln, a fluidized bed reactor, such as a bubbling fluidized bed roaster, a circulating fluidized bed roaster, an annular fluidized bed roaster, and a flash reactor.
  • the heating step (a) is accomplished in a fluidized bed furnace. This ensures a very good mass and heat transfer.
  • the fluidized bed fur- nace is a bubbling fluidized bed furnace or a circulating fluidized bed furnace.
  • sulfur-poor metal oxide concentrate refers to concentrates having sulfur content below 10 % w/w and comprising more than 40 % w/w metal oxide, in particular from 50 to 90 % w/w metal oxide, more particularly from 60 to 70 % w/w metal oxide.
  • Sulfur-poor metal oxide concentrate pre-treated with the method of the invention is preferably a concentrate having sulfur content from 0.2 to 8 % w/w, more preferably from 3 to 7 % w/w.
  • sulfur-poor metal oxide concentrate comprises niobium oxide (e.g. Nb 2 O 5 ), in particular from 30 to 60 % w/w, more particularly from 50 to 60 % w/w.
  • sulfur comprised in the sulfur-poor concentrate is mostly pyrite.
  • the sulfur-poor metal oxide concentrate comprises from 30 to 40 % w/w Nb and 5 to 8 % w/w Fe.
  • the carbon content of the sulfur-poor metal oxide concentrate is so low, that it together with sulfide it does not produce enough heat for heating material to required temperature.
  • the carbon content of the oxide concentrate affects the heat value of the concentrate and thus oxide concentrate with particularly low carbon content cannot be treated with conventional pre-treatment methods.
  • the method of the invention advantageously provides sulfur- depleted metal oxide calcine having sulfur content below 0.2 % w/w, more preferably below 0.15 % w/w.
  • Such pre-treated oxide calcine can be processed in by suitable hydrometallurgical methods known by person skilled in the art for recovering the valuable metals comprised in the said pre-treated oxide calcine
  • the term "calcine" as used herein and hereafter refers to a product obtained by heating a concentrate to a high temperature but below the melting or fusing point, causing loss of moisture, reduction or oxidation, and at least partial the decomposition of carbonates and other compounds.
  • the method of the invention is applicable for removal of sulfur from a sulfur-poor metal oxide concentrate regardless of whether the sulfur is present as sulfate(s), sulfide(s), or both.
  • the conversion of sulfides and/or sulfates to corresponding oxides with oxygen is dependent on the local oxygen concentration.
  • Oxygen can be introduced into the heating step (a) for example as air, oxygen enriched air, or other oxygen containing gas, preferably as air or oxygen enriched air.
  • the required amount of oxygen in the heating step (a) depends on the sulfur content of the oxide concentrate and the desired sulfur content of the pre-treated oxide concentrate and the mineralogical nature of the sulfides and/or sulfates as well as carbon and/or carbonates comprised in the sulfur-poor metal oxide concentrate.
  • the external fuel source is preferably liquid and/or gaseous fuel, such as methane, propane, butane, natural gas or heavy oil.
  • Use of solid fuel sources, such as sulfur bearing carbonaceous materials, is not desirable as they are easily retained in the solid concentrate and thus would not allow ob- taining pre-treated material with a very low sulfur and carbon content.
  • the fuel source is preferably proved to the roasting stage through one or more fuel lances.
  • Fuel lance supplies the liquid and/or gaseous fuel into the furnace by a liquid-fuel passage that extends into the furnace chamber. Fuel is oxidized with oxygen containing fluidizing media. The required number of fuel lances de- pends on the need of additional energy and the capacity of the plant. Fuel lances can be provided on one or more, preferably one or two, levels depending on the size of the furnace. The required amount of fuel is depended on the desired temperature of the heating step (a) the reaction kinetics, and thermodynamic stability.
  • the temperature of the heating step (a) must be kept within oxide stability range. This is dependent of the nature of the sulfur-poor metal oxide concentrate, but varies typically from 500 to 1000°C depending on the minerals. Temperature must also be minimized to minimize the need of external fuel source.
  • the retention time of step (a) is depended on the mineralogical nature of the sulfur-poor ore. For example sulfur in present as a pyrite can be easily removed in minutes.
  • Figure 1 and Figure 2 show calculations relating to suitable conditions regarding temperature and oxygen pressure of the heating step (a) for oxidation of sulfur comprised in a sulfur-poor metal oxide concentrate comprising sulfur mainly as pyrite (iron sulfide) in such manner that sulfide oxi- dizes to iron oxides (FeO, Fe3O 4 and/or Fe 2 Os) and no iron sulfates (FeSO 4 ) are formed.
  • a sulfur-poor metal oxide concentrate comprising sulfur mainly as pyrite (iron sulfide) in such manner that sulfide oxi- dizes to iron oxides (FeO, Fe3O 4 and/or Fe 2 Os) and no iron sulfates (FeSO 4 ) are formed.
  • the process conditions of the heating step (a) are directly affected by the nature of the pre-treated sulfur-poor metal oxide concentrate the nature of the said oxide concentrate is preferably determined before- hand and the process conditions are selected accordingly.
  • the process conditions of the heating step (a) are determined by the steps of: (i) analyzing the nature of the sulfur com- pound(s) and the nature of the metal oxide(s) of the sulfur-poor metal oxide concentrate; and (ii) selecting the process conditions in such manner that the metal oxide retains it stability while the sulfur compounds are oxidized and/or thermally decomposed.
  • the nature of the sulfur compound(s) and the oxide(s) of the sulfur- poor metal oxide concentrate in step (i) can be analyzed by methods known suitable by a person skilled in the art.
  • the main elements of the sulfur-poor metal oxide concentrate can for example be analyzed by inductively coupled plasma (ICP) mass spectrometry.
  • the sulfur content of the oxide concentrate can be determined for example by an elemental analyzer utilizing combustion techniques, such as Eltra CS2000.
  • the chemical composition of the main components of the oxide concentrate can be analyzed for example by field emission scanning electron microscope.
  • the main mineralogy of the oxide concentrate can be determined for example by X-ray diffraction.
  • the nature of the sulfur compound(s) and the nature of the oxide(s) of the sulfur- poor concentrate is analyzed at least by X-ray diffraction.
  • step (ii) The process conditions in step (ii) are then selected by performing stability calculations and utilizing thermochemical estimations, such as those shown in Figure 1 and/or Figure 2.
  • the temperature of the heating step (a) can be further determined by testing the reaction temperature of the sulfur-poor metal oxide concentrate using a thermogravimetric/differential scanning calo- rimetric (TG/DSC) method which indicates the temperature(s) where the sulfur compound(s) are oxidized and/or thermally decomposed.
  • TG/DSC thermogravimetric/differential scanning calo- rimetric
  • step (b) is accomplished by a cyclone.
  • cooling of calcine in step (c) is accomplished by a fluidized bed cooler.
  • the method of the invention is particularly suitable for the sulfur- poor metal oxide concentrate comprising small amounts chlorides and/or fluorides.
  • the sulfur-poor metal oxide concentrate comprises chlorides and/or fluorides.
  • the sulfur-poor metal oxide concentrate can comprise from 0 to 4 % w/w, in particular from 1 to 2 % w/w, chlorides and/or fluorides.
  • these compounds are volatilized and when present as gaseous HF and HCI in the off-gas also removed in the scrubbing step (e). It is not possible to recycle off-gas comprising HCI and/or HF. The presence of HCI and/or HF also prevents utilization of the off-gas in an acid plant.
  • step (e) can be accomplished for example by regenerative scrubbing methods to recover sulfur.
  • the wash chemicals can be recycled.
  • SO2 and/or HCI and/or HF are present scrubbing in step (e) can be done for example with an aqueous alkaline solution, such as NaOH (aq) and CaOH 2 (aq).
  • FIG 3 illustrates an example of the method of the present inven- tion.
  • sulfur-poor metal oxide concentrate (1 ) and an external fuel source (2) are introduced into a roaster (A) and heated in presence of preheated air (3) to oxidize sulfur compounds contained in the sulfur- poor metal oxide concentrate to corresponding oxides and/or to thermally decompose the said sulfur compounds, to obtain a gas/calcine mixture (4) com- prising sulfur-depleted metal oxide calcine and sulfur-containing off-gas.
  • the gas/calcine mixture is then introduced into a cyclone (B) and separated to obtain a sulfur-depleted metal oxide calcine (5) and a sulfur-containing off-gas (6).
  • the sulfur-containing gas (6) can analyzed with a gas analyzer (G) and the process conditions of the roaster (A) can be adjusted accordingly.
  • the obtained sulfur-depleted metal oxide calcine (5) is then cooled in a fluidized bed cooler (C) where the heat of the said calcine is utilized to heat the air (3') entering the heating step (a). Further the air (3') used and in the fluidized be utilized as a warm gas (13) in drying of the concentrate (1 ).
  • the sulfur-containing off-gas (6) is cooled by quenching with water (8) in a quencher (D) and the thus obtained cooled off- gas (7) is scrubbed with an aqueous alkaline solution (9) to produce cleaned off-gas (10).
  • the wash waters (1 1 ) and (12) from the quencher (D) and the scrubber (E) can be further treated (F) to recover sulfur removed from the off- gas.
  • ND2O 5 concentrate was analyzed chemically and its mineralogy and particle size distribution where determined.
  • the particle size of the oxide con- centrate was 88 ⁇ and dgo 207 ⁇ .
  • the oxide concentrate consisted mainly of zoned to homogeneous pyroch lore-col urn bite and pyrite grains.
  • the concentrate comprised Nb 36.4 % w/w, S 7.61 % w/w, CI 0.83 % w/w and F 1 .8 % w/w.
  • a 150g sample of the oxide concentrate was roasted in a laboratory-scale fluidized bed furnace that comprised a vertical trans temp 21 ⁇ 2" x 20" furnace and a fused quartz tube.
  • a porous quartz sinter was used as a grate and aided in distributing the gas flow. Roasting was performed as a batch operation and at temperature of 750 °C under an air flow. The sulfur and carbon contents of the sample were analyzed periodically.
  • Sulfur and carbon content of the thus obtained product was 0.13 and 0.06 % w/w, respectively, after two minutes roasting at temperature of 750 °C.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Mechanical Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Geochemistry & Mineralogy (AREA)
  • Geology (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Environmental & Geological Engineering (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Manufacture And Refinement Of Metals (AREA)

Abstract

La présente invention concerne un procédé de prétraitement d'un concentré d'oxydes métalliques pauvre en composés soufrés, comprenant les étapes consistant à : utiliser un concentré d'oxydes métalliques pauvre en composés soufrés ayant une teneur en composés soufrés inférieure à 10 % p/p ; (a) chauffer le concentré d'oxydes métalliques pauvre en composés soufrés à une température élevée et en présence d'oxygène et d'une source combustible externe pour oxyder en oxydes correspondants les composés soufrés contenus dans le concentré pauvre en composés soufrés et/ou pour décomposer thermiquement lesdits composés soufrés afin d'obtenir un concentré d'oxydes appauvri en composés soufrés et un rejet gazeux contenant des composés soufrés ; (b) séparer le résidu de calcination des oxydes métalliques appauvri en composés soufrés du rejet gazeux contenant des composés soufrés ; (c) refroidir le résidu de calcination des oxydes appauvri en composés soufrés obtenu ; (d) refroidir le rejet gazeux par trempe ; et (e) épurer le rejet gazeux refroidi de sorte à récupérer les composés soufrés.
PCT/EP2013/074831 2013-11-27 2013-11-27 Grillage de concentrés d'oxydes métalliques pauvres en composés soufrés WO2015078493A1 (fr)

Priority Applications (3)

Application Number Priority Date Filing Date Title
PCT/EP2013/074831 WO2015078493A1 (fr) 2013-11-27 2013-11-27 Grillage de concentrés d'oxydes métalliques pauvres en composés soufrés
CA2930762A CA2930762C (fr) 2013-11-27 2013-11-27 Grillage de concentres d'oxydes metalliques pauvres en composes soufres
AP2016009226A AP2016009226A0 (en) 2013-11-27 2013-11-27 Roasting of sulfur-poor metal oxide concentrates

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/EP2013/074831 WO2015078493A1 (fr) 2013-11-27 2013-11-27 Grillage de concentrés d'oxydes métalliques pauvres en composés soufrés

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WO2015078493A1 true WO2015078493A1 (fr) 2015-06-04

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3640679A (en) * 1969-02-06 1972-02-08 Molybdenum Corp Process for recovery of columbium
GB1305356A (fr) * 1969-02-06 1973-01-31 Molybdenum Corp
WO2000050652A1 (fr) * 1999-02-26 2000-08-31 Mintek Traitement de concentres de sulfure metallique par grillage et par reduction par fusion dans un four a arc
WO2010003693A1 (fr) * 2008-07-11 2010-01-14 Outotec Oyj Procédé et installation de production de calcinats

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3640679A (en) * 1969-02-06 1972-02-08 Molybdenum Corp Process for recovery of columbium
GB1305356A (fr) * 1969-02-06 1973-01-31 Molybdenum Corp
WO2000050652A1 (fr) * 1999-02-26 2000-08-31 Mintek Traitement de concentres de sulfure metallique par grillage et par reduction par fusion dans un four a arc
WO2010003693A1 (fr) * 2008-07-11 2010-01-14 Outotec Oyj Procédé et installation de production de calcinats
US20110195016A1 (en) * 2008-07-11 2011-08-11 Outotec Oyj Process and plant for producing calcine products

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
E ECCLESTON ET AL: "Development of roasting parameters for the ConRoast process with low-sulphur feedstock", JOURNAL OF THE SOUTH AFRICAN INSTITUTE OF MINING AND METALLURGY, vol. 109, no. 1, 1 January 2009 (2009-01-01), ZA, pages 65 - 69, XP055131208, ISSN: 0038-223X *

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CA2930762C (fr) 2020-10-27
AP2016009226A0 (en) 2016-05-31
CA2930762A1 (fr) 2015-06-04

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