WO2014127993A1 - Procédé de production de terres rares - Google Patents

Procédé de production de terres rares Download PDF

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Publication number
WO2014127993A1
WO2014127993A1 PCT/EP2014/052183 EP2014052183W WO2014127993A1 WO 2014127993 A1 WO2014127993 A1 WO 2014127993A1 EP 2014052183 W EP2014052183 W EP 2014052183W WO 2014127993 A1 WO2014127993 A1 WO 2014127993A1
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WO
WIPO (PCT)
Prior art keywords
rare earth
mixture
slag
containing compound
heat treatment
Prior art date
Application number
PCT/EP2014/052183
Other languages
German (de)
English (en)
Inventor
Karl Bernhard Friedrich
Marc Hanebuth
Stephanie KRUSE
Alexander Tremel
Original Assignee
Siemens Aktiengesellschaft
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 Siemens Aktiengesellschaft filed Critical Siemens Aktiengesellschaft
Publication of WO2014127993A1 publication Critical patent/WO2014127993A1/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
    • C22B59/00—Obtaining rare earth metals
    • 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
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/10—Process efficiency
    • Y02P20/133—Renewable energy sources, e.g. sunlight

Definitions

  • the invention relates to a process for the extraction of rare earths from rare earth element-containing phosphates according to claim 1.
  • Rare earth elements also referred to as lanthanides in chemistry, are needed in many electronic devices and in the manufacture of magnets.
  • the rare earth element neodymium is an important component of permanent magnets used in wind generators.
  • the treatment and separation of rare earth elements is basically chemically complex, since the rare earth elements in nature very finely distributed, socialized (especially with each other) and occur in low concentrations.
  • the rare earth elements are present in phosphatic compounds, in particular in the crystal structure of the monazite or xenotime or as minor constituents in the apatite, which in turn occur finely distributed in deposits which may also contain iron.
  • Rare earth phosphates are converted in the prior art in a complex high temperature process with sulfuric acid to a sulfate.
  • the sulphates of the rare earth metals are generally more soluble in water than the phosphates.
  • the conversion process using sulfuric acid is ecologically very critical and technically difficult to handle.
  • the object of the invention is to provide a method for the production of rare earths, which is ecologically less problematic compared to the prior art and is technically easier to handle.
  • the solution of the problem consists in a method having the features of claim 1.
  • the inventive method for the production of rare earth includes the following steps. First, a rare earth element-containing phosphate such as monazite is mixed with carbon. At least one other compound capable of forming slag is also fed to the process.
  • the formation of slag is understood here as the property of the compound to partially separate components, slags are not necessarily from liquid often.
  • This further slag-forming compound is an oxygen-containing compound of the elements sodium, calcium, magnesium, potassium, lithium, aluminum, iron or Bor.
  • the rare earth element-containing mixture may contain other ingredients such.
  • the method described has the advantage over the prior art that the sparingly soluble rare earth phosphate is converted to an alternative rare earth compound, in this case rare earth oxide, without having to use a concentrated acid at high temperatures. It is a relatively easy to handle melting process in which the above compounds together form a melt and thereby the desired Reaction takes place. Incidentally, the reaction generally also produces elemental phosphorus or phosphorus oxide, which can be separated at low cost and is obtained as a by-product.
  • rare earth elements in particular the so-called lanthanides, including lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, ytterbium and lutetium understood, but there are because of their chemical similarities in this case here also counted the yttrium and scandium.
  • Rare earths are in turn compounds of rare earth elements, in particular their oxides, which do not include rare earth phosphates.
  • the oxygen-containing compound forming the slag is an oxide, a carbonate or hydroxide of sodium, calcium, magnesium, potassium, lithium, aluminum, iron or boron or a mixture thereof.
  • the compounds serve as refining agents, which favor the ongoing reactions or make it possible.
  • Particularly expedient boron oxide or the less expensive borax has resulted.
  • the boron oxide has a very low melting point, whereby the temperature of the heat treatment can be lowered, which makes the process considerably less expensive.
  • the heat treatment takes place in an advantageous embodiment in an electric arc furnace. This is particularly suitable for heat input, for igniting the reaction and for handling a mineral melt.
  • the substance mixture can be provided after the heat treatment with an aqueous base, whereby the oxygen-containing compound can be selectively solved ons communications to the other constituents of the reaction product. This is a reuse of the oxygen-containing compound, in particular the relatively expensive boron oxide possible.
  • the reaction product in a further process step, can be provided with a preferably dilute aqueous inorganic acid, in particular hydrochloric acid.
  • a preferably dilute aqueous inorganic acid in particular hydrochloric acid.
  • FIG. 1 shows a schematic chain of method steps for
  • Figure 2 is a schematic representation of the heat treatment of a rare earth-containing mixture.
  • the mineral monazite is a phosphate in which the metal ions often occur in the form of rare earth metals, in particular cerium, neodymium, lanthanum or praseodymium. Within a particle, this is not a homogeneous composition of rare earth metals, but in the crystal structure, the lattice sites of the cations are occupied by different rare earth metals in different concentrations.
  • the starting raw materials containing the monazite mineral are first ground very finely and treated in a flotation unit 2 so that the monazite separates as well as possible from the other mineral constituents.
  • the monazite is dried and treated according to the prior art in an oven, such as a rotary kiln 4, after prior mixing with sulfuric acid.
  • the phosphates are converted into sulfates. This process in the rotary kiln takes place at temperatures up to 650 ° C.
  • the conversion of phosphate into sulfate is expedient since the rare earth sulfates are significantly more soluble in water than the phosphates of the rare earth metals.
  • the sulfuric acid-containing solution of rare earth sulfates is neutralized after treatment in the rotary kiln 4 and a subsequent leaching step in a neutralizer 6, ie, the pH is increased by addition of a basic substance, whereby unwanted substances are precipitated and separated, so that in the remaining liquid an aqueous rare earth sulfate solution is present.
  • a neutralizer 6 ie, the pH is increased by addition of a basic substance, whereby unwanted substances are precipitated and separated, so that in the remaining liquid an aqueous rare earth sulfate solution is present.
  • the described substitution of phosphate ions by sulfate ions with the aid of sulfuric acid is ecologically problematic and technically difficult to handle. Therefore, in this context, an alternative technology will be described, which will be discussed in more detail.
  • This resulting solution of a rare earth compound (sulfate, nitrate, chloride or the like) is usually in so-called mixer-settler devices of a liquid / liquid extraction, ie a separation subjected.
  • the solution is prepared by mixing an extraction medium dissolved in organic solvents such as kerosene, possibly with further additives, so that the rare earth cations, which have slightly different ion diameters for the same charge, reach different concentrations either in the aqueous part of the solution or in the organic solution Enrich part of the solution.
  • the organic phase and the aqueous phase of the mixture are alternately mixed and separated again in a multi-stage separation process, so that certain rare earth ions, depending on the extractant in the organic phase, increasingly concentrated until finally these ions are present in sufficient purity in one phase. This may require up to 200 separation steps per element.
  • the rare earth metals thus separated are subsequently precipitated in a precipitation device 10 by addition of a carbonate or oxalate, so that the corresponding rare earth carbonate or oxalate accumulates at the bottom of the precipitation device 10.
  • This is in turn calcined in a calcination, for example in a continuous furnace, through which a hot air stream is passed.
  • a discrete rare earth oxide is present.
  • This discrete rare earth oxide may optionally be converted into a lower melting salt, e.g.
  • a lower melting salt e.g.
  • a fundamental core task in the recovery of rare earth metals in their pure form is the conversion of a rare earth phosphate, which is a common natural manifestation of rare earth elements, into a more easily handled and more easily soluble compound of the rare earth element. Depending on the ore and deposit, rare earth phosphates occur in different mineral structures.
  • Monazite, xenotime and apatite are customary, although the process described above is customary in particular for the two first-mentioned mineral structures, but the conversion of the rare earth phosphate into all processes is necessary.
  • the present process differs from the conventional art using sulfuric acid in a rotary kiln particularly in that a mixture of a rare earth phosphate (e.g.
  • Apatite structure carbon and an oxygen-containing compound of any one of sodium, calcium, magnesium, potassium, lithium, aluminum, iron or boron.
  • oxygen-containing compound is understood inter alia the oxide, hydroxide or carbonate.
  • this oxygen-containing compound of one of these elements is a slag-forming substance by which a melting of the entire mixture is promoted.
  • Particularly suitable is the boron oxide (B 2 0 3 ).
  • this boron oxide in pure form is relatively expensive, this can alternatively also a low-melting borax, which is a mineral from the mineral class of borates with a typical chemical formula Na 2 [B 4 0 5 (OH) 4 ] '8H 2 0.
  • the Borax is inexpensive to purchase, possibly on a Recovery from the process can be dispensed with.
  • a mixture of the enumerated oxygen-containing compound can be used for slag formation in order to optimize the process costs and to adjust the process parameters such as, for example, the melting point and the recovery.
  • This mixture is first placed in an electric arc furnace, which is illustrated by the box 30 in FIG.
  • a heat treatment is carried out which essentially results in that the mixture can be melted, wherein it reacts essentially, purely by way of example, illustrated by the use of boron oxide as the slag-forming compound, according to the following reaction equation:
  • SE is generally a rare earth element.
  • the stoichiometric factor x can vary depending on the composition of the reaction mixture. This reaction is conveniently carried out in the described electric arc furnace at a process temperature between 1100 ° C and 1800 ° C, particularly advantageous is a temperature range between 1200 ° C and
  • the liquid mixture is discharged from the arc furnace and solidified.
  • the phosphate anion with which the rare earth element has entered into a compound is replaced by oxygen ions.
  • the carbon present in the mixture is oxidized and converted to carbon monoxide and further to carbon dioxide.
  • elemental Phosphorus or phosphorus oxide which can be separated as a valuable element and can be used profitably elsewhere.
  • the oxygen-containing compound which is illustrated here by the example of the preferred boron oxide, can also be considered to be inert and has only catalytic and slag-forming properties.
  • the oxygen-containing compound for example when using a carbonate or hydroxide of said elements, also takes part in the reaction, it also being possible for other rare earth compounds to form in addition to the rare earth oxide.
  • the reaction can be varied according to the ground substance involved, but it is important that the sparingly soluble rare earth phosphate is converted to a more easily soluble compound.
  • the box 36 it may be expedient to provide the solidified reaction product according to the right side of the equation described above with an aqueous base, for example sodium hydroxide, for the selective dissolution of the boron oxide.
  • an aqueous base for example sodium hydroxide
  • the recovery of the boron oxide by means of methods that belong to the prior art, possible.
  • corresponding chlorides in particular the rare earth metal chlorides, which are likewise advantageously processed further in the overall process described above, are formed.
  • the exhaust gas of the process is less polluting the environment, also in the described process, another valuable element, namely phosphorus generated. Furthermore, it is possible by the described method to influence the solubility of the obtained rare earth compound by a defined addition of the slag forming agent and to adapt it to the requirements of the subsequent rare earth recovery process.

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

Abstract

L'invention concerne un procédé de production d'oxydes de terres rares et comprend les étapes suivantes : mélanger un phosphate contenant des terres rares avec du carbone et un composé des éléments sodium, calcium, magnésium, potassium, lithium, aluminium, fer ou bore ou un mélange de ceux-ci, ledit composé étant à base d'oxygène et apte à former des scories. Enfin, ledit mélange est soumis à un traitement thermique à une température comprise entre 1100 et 1800°C, ce qui donne lieu à la formation d'un oxyde de terres rares.
PCT/EP2014/052183 2013-02-25 2014-02-05 Procédé de production de terres rares WO2014127993A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE102013203048.7A DE102013203048A1 (de) 2013-02-25 2013-02-25 Verfahren zur Gewinnung von Seltenen Erden
DE102013203048.7 2013-02-25

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WO2014127993A1 true WO2014127993A1 (fr) 2014-08-28

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DE (1) DE102013203048A1 (fr)
WO (1) WO2014127993A1 (fr)

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4135921A (en) * 1978-03-07 1979-01-23 The United States Of America As Represented By The Secretary Of The Interior Process for the preparation of rare-earth-silicon alloys
CN1511966B (zh) * 2002-12-30 2011-06-08 北京有色金属研究总院 一种高含铁稀土原矿的选矿工艺

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1981126A (en) * 1932-04-25 1934-11-20 Ig Farbenindustrie Ag Decomposition of rare earth metal bearing ores
GB674400A (en) * 1949-07-21 1952-06-25 Produits Chim Terres Rares Soc Treatment of monazite
NL129105C (fr) * 1965-11-22

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4135921A (en) * 1978-03-07 1979-01-23 The United States Of America As Represented By The Secretary Of The Interior Process for the preparation of rare-earth-silicon alloys
CN1511966B (zh) * 2002-12-30 2011-06-08 北京有色金属研究总院 一种高含铁稀土原矿的选矿工艺

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
XING P F ET AL: "High temperature dephosphorization behavior of monazite concentrate with charred coal", TRANSACTIONS OF NONFERROUS METALS SOCIETY OF CHINA, NONFERROUS METALS SOCIETY OF CHINA, CN, vol. 20, no. 12, 1 December 2010 (2010-12-01), pages 2392 - 2396, XP027584066, ISSN: 1003-6326, [retrieved on 20101201] *
ZHANG SHIRONG ET AL: "Study on behavior of carbon reduction of monazite concentrate", JOURNAL OF RARE EARTHS, INTERNATIONAL ACADEMIC PUBLISHERS, BEIJING, CN, vol. 18, no. 3, 1 September 2000 (2000-09-01), pages 178 - 181, XP009177789, ISSN: 1002-0721 *

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