FR2508931A1 - PROCESS AND DEVICE FOR TREATING ORE OR ORE CONCENTRATE - Google Patents

Abstract

THE INVENTION RELATES TO A PROCESS AND A DEVICE FOR PROCESSING AN ORE OR CONCENTRATE OF RARE EARTHS, FOR EXAMPLE MONAZITE OR BASTNASITE, OR A MIXTURE OF THE TWO. ACCORDING TO THE INVENTION, A PULVERIZED ORE SLUDGE OR RARE EARTH CONCENTRATE MIXED WITH AN AQUEOUS SOLUTION OF AN ELECTROLYTE, FOR EXAMPLE SODIUM HYDROXIDE, IS SUBJECT TO INDUCTION HEATING TO FACILITATE THE DISSOCIATION AND REDUCTION OF THE MINERAL OR CONCENTRATE OF RARE EARTHS. THE DEVICE ACCORDING TO THE INVENTION INCLUDES A TREATMENT TANK 1, MEANS 4, 5 FOR SUPPORTING A MASS 2 FORMED BY THE ORE OR CONCENTRATE AND THE ELECTROLYTE, and MEANS 6 FOR HEATING BY INDUCTION OF THE MASS.

Description

t Process and device for treating ore or

rare earth concentrate.

  The present invention generally relates to a

  Dissociation commonly used in the refining of rare earth ores. More particularly, it relates to a method and a device for the treatment of ores or concentrates of rare earths, for example monazite and / or bastn 9 site. to dissociate them into a rare earth compound, for example R (OH) 3, from which the desired rare earth element R may be easily recovered, such as lanthanum, cerium, praseodymium, neodymium, samarium or gadolinium, or a mixture of these elements or "mischmetall" (hereinafter called

  generally rare earth substance).

  It is known to extract rare earth substances from a variety of

  ora, such as monazite, bastnesite, gadolinite and xenotime that contain rare earth concentrates in the form of (Th, R) PO 4, RFCO 3, (Be, Fe) R 2 Si 2010 and RPO 4 respectively. refining, it is therefore necessary to treat each of these ores or concentrates of rare earths to separate or release the rare earth compound from other components The stage of separation or dissociation has so far been achieved in a purely chemical manner Thus, monazite, bastnastitis or xenotime have been treated

  with sulfuric acid, sodium sulphate, hydro-

  sodium hydroxide, hydrogen chloride and ammonium chloride to obtain the rare earth compound-in the form of R (OH) 3 or R 203, separated from thorium sulfate, hydrogen phosphate, sodium, carbon dioxide, silicon fluoride, hydrogen fluoride, sodium phosphate, sodium hydroxide, thorium hydroxide, thorium ions and sulphate radicals

and / or phosphate.

  Not only have these prior dissociation processes required

  a high concentration of the reagent: H 2504, Na SO 4, HC 1, NH 3 Cl, which increases the colts, but they also require a relatively high reaction temperature between 200 and 2501 C, or around 1500 C, to maintain

  for several hours Moreover, it inevitably emerges-

  large quantities of toxic gases such as 502 and HF

  and toxic alkaline mists, requiring

  Therefore, it should be noted that previous dissociation processes are unsatisfactory, not only from the standpoint of saving energy and raw materials, but also from the point of view of the economics of energy saving. installation and costs

  rare earth elements thus produced.

  Another problem encountered so far in the field of

  rare earth treatment is a dissociative process

  tion (for example, the alkali dissociation process

  lin) applicable to a particular rare earth ore (eg monazite) generally does not apply to another ore (eg bastn Ssite) Thus, when two different types of rare earth ores exist in the same ore, as per example that of the Baiyun mine in China, which contains 40% monazite and 60% bastnâsite, the previous techniques have a yield

  extremely low or even can not be implemented.

  It is therefore an object of the invention to provide a new and improved process for dissociating rare earth ores or concentrates, for example monazite and / or

  bastnasite, in rare earth compounds, this process comprises

  relatively simple, energy-efficient and resource-efficient stages of operation that can produce the desired rare earth substances

  at a reduced cost, which may even apply to

  very mixed rare earth ores (eg monazite

  more bastnâsite) and which, in practice-i is usually inde-

  during the nature of the source of rare earths.

  It is also an object of the invention to provide a process for dissociating ores and / or rare earth concentrates, which makes it possible to obtain a larger quantity of suitable rare earth compounds, such as a rare earth hydroxide. , (R (OH) 3), a rare earth sulfate (R (504) 3), or a rare earth chloride e RC 13) and which is capable of reducing the presence of gases and toxic fluids

  in order to eliminate costly anti-pollution

large and large.

  It is also an object of the invention to provide a new

  improved device for dissociating ores or concentrates

  very rare earths by composing it with rare earths

  which is a relatively simple device

  economically, easily adaptable to treat a variety of rare earth ores

  eliminate environmental pollution problems.

  The process according to the invention is a physicochemical process in which, in general, a rare earth ore or concentrate is mixed with an aqueous solution of an electrolyte to form a mud of the mixture, and is heated by induction. this mud to facilitate the reduction of the

  ore or concentrate by the electrolyte.

  Specifically, this sludge can be heated by passing through a high frequency electric field, whose frequency is between 50 Hz and 100 l Ez, created by

  As an alternative, the mud can be heated

  by directing towards it a beam of mr icri o-waves with a frequency between 300 M Hz and 300 G Hz to heat

the mud by induction.

  The ore or concentrate may contain a rare earth compound in the form of an oxide of at least one element

rare earth.

  The ore or rare earth concentrate may be at least one mineral selected from the group consisting of monazite, bastn Msite, gadolinite, and xenotime. For example, a mixture of monazite and bastnite may be effectively

  treated according to the present process, despite the previ-

  than such mixed rare earth ore can

  be difficult to treat or with a fall in

considerably.

  The electrolyte can be at least one of the substances selected from the group consisting of potassium acetate, ammonia, ammonium chloride, sodium chloride, sulfuric acid, sodium carbonate, sodium hydroxide and potassium hydroxide. We observed

  an alkaline compound, such as sodium hydroxide,

  especially in the case of the present invention.

  The ore or rare earth concentrate sprayed should preferably have a grain size of between 37

  and 150 vm (100-400 mesh) As usual, spraying

  before the mixing with the electrolyte, although the ore or concentrate may also be

  sprayed after being mixed with the electrolyte.

  The invention also relates to a device for treating a rare earth ore or concentrate, which comprises a treatment tank, support means in the treatment tank for retaining a mass of mud formed by mixing the ore or the concentrate. rare earths with

  an aqueous solution of electrolyte, and heating means

  induction iron the mass to facilitate the reduction

  rare earth ore by the electrolyte.

  Specifically, the heating means may comprise

  ter winding means arranged to surround the mass

  and a current source for passing an electrical current

  A variant of the high-frequency drive, with a frequency of between 50 Hz and 100 k Hz, through the winding means for heating the mass by induction Alternatively, the heating means may comprise a magnetron for exposing the mass to a microphone beam. with a frequency of between 300 M Hz

  and 300 G Ez for heating the mass by induction.

  The invention will be well understood on reading the description

  detailed, given by way of example only, of several preferred embodiments, in connection with the attached drawing, in which:

  FIG. 1 is a schematic view showing a first

  re embodiment of the present invention; and FIG. 2 is a schematic view illustrating a second

  embodiment of the present invention.

  Referring now to FIG.

  positive embodiment according to the invention comprises a treatment tank 1,

  has built up, on the inside of its internal surfaces,

  anti-acid and / or anti-alkaline material The tank 1 is also rigid and is made so that its internal volume

  hermetically A mass of material 2 to be treated is introduced

  in this volume through an opening of the opening

  It is equipped with a door 3, which is closed for the operation of the device. In the tank 1, the material 250893 2 to be treated, which is a mixture of ore or

  rare earth concentrate previously pulverized in parti-

  of which the particle size is included, for example, between

  37 and 75 V m, with a liquid electrolyte and which presents itself

  te in the form of a sufficiently viscous paste or mud

  mixed or kneaded, is introduced into the tank 1 and

  placed in a tray 4 mounted on a table 5 inside.

  We also see in the tank 1 a winding 6 arranged

  to surround matter 2 and excited by a source of cou-

  high frequency reactor 7 for induction heating the material

  2 and create electric shocks (micro discharges or sparks)

  those) between the particles of this material

  not shown are provided for winding.

  The current source 7 is equipped with a control unit 8 to adjust the value of the output current flowing from the source 7 through the winding 6 or the heating energy applied to the material 2 and the time of supplying the heating current or energy Thus, the output current of the current source 7 can be pulsating and the pulse duration and the pulse interval, as well as their magnitude, can be regulated by the unit. The gases and mists produced during the induction heating and the treatment of the material 2 can be discharged from the vessel 1 through a conduit 9 and discharge means 10, which may comprise a vacuum pump, and a gas treatment unit A valve 11 is provided in the duct 9 In addition, a gas supply 12 is provided for the supply of a suitable gas in the treatment tank 1 via a duct 13 in order to trigger the reactions of treatment in the tank 1, dilute the gases and mists produced to combat the risk of fire and pollution, to facilitate the treatment of these gases and mists in the unit 10 and / or to maintain the volume in the tank 1 under appropriate pressure and temperature conditions A valve 14

is provided in conduit 13.

  Ore powder or rare earth concentrate

  The material 2 is a mass of rare earth ore previously pulverized and then gravitated to remove impurities such as silica sand and further to a magnetic or electromagnetic concentration to remove iron ore from the atmosphere. This pretreatment of concentrations is here advantageous in order to use, with a good yield, the electrical energy consumed during the induction heating and the treatment with a rare earth content of at least 60% by weight or by volume. However, it should be noted that the process of this invention can be applied to a rare earth ore

  having a tainted soil content, say, for example, inferior.

  than 50% by weight or volume.

  think of gravity concentration and concentration

  magnetic or electromagnetic interference if the cost of such

  Concentration is greater than the cost of the excess electrical power required due to the higher concentration of impurities in the implementation of the present process.

  Although a rare earth concentrate is itself extremely

  resistant or dielectric, by mixing it with a

  liquid electrolyte, we obtain a body of resistivity mo-

  for example of the order of one ohm-centimeter, and this body can be effectively heated by induction and can effectively develop electric discharges among the particles When the mixed body 2 is heated to more than 1000 C, or about, the water evaporates and gasses,

  giving rise to gaseous bubbles in the midst of

  These bubbles tend to expand outwards, the parasitic current created through the

  material 2 by the passage of the high frequency current through

  towards winding 6 tends to cease.

  localized and dispersive development of micro-discharges or spark discharges (in the form of points of white and red blue light) among the particles in the mass 2 The particles of rare earth concentrate are thus exposed to localized adjacent discharge columns and , at the elevated temperature at the point of discharge and in the presence of the reaction electrolyte, these particles decompose and are reduced.

  example of caustic soda (NaOH), the result is

  rare earth hydroxide (R (OH) 3) The presence of water makes that unless supplying an extremely energy

  high or extraordinarily high de-heating energy

  high, mixture 2 does not reach a temperature higher than 2000 C It can be assumed that at least a portion of the particles of rare earth

  temperature of the order of 1000 C just suitable for dissolving

  When these particles come into contact with a column of sparks or

  microdiscs, we see trigger the desired reactions.

  In another embodiment of the invention shown in the

  Figure 2, Induction Heating of Rare Earth Ore

  res 2 is obtained by microwaves emitted by a tube of

  microwaves, for example a magnetron.

  The current source 16 is powered by a power source 16 with a control unit 17. The power source 16 is set by the control unit 17 to emit a micu wave beam from a tube 15 of a frequency of between 300 M Hz. and 300 GHz The control unit 17 is also used to adjustably vary the energy of the microwaves as well as their duration and the interval between the waves. In the arrangement of FIG. 2, the same reference marks are used. to designate the same parts as in FIG. 1 (where the parts operate in the same manner) and the material 2 is represented by three or four masses instead of constituting the single mass of FIG. 1 In addition, the tray 4 is mounted on a turntable 18, itself rotatably mounted

  on the base 5 and there is provided a fan 19 for regulating

  larize the distribution of microwaves emitted by the tube

on the masses 2 in the tray 4.

  The microwave tube 15 utilizes the principles of electromagnetic induction heating or dielectric heating and currently operates to emit high frequency waves in the range of 1 to 3 G Ez.

  each of the masses 2 is exposed to a beam of micro-

  waves, it is inductively heated due to the loss

  dielectric created through it At the same time,

  They tend to accumulate on the particle surfaces of the rare earth concentrate and sparks

  or local microdownloads through the interstices

  particles in each mass 2 When mass 2 is

  inductively heated by dielectric heating at a time

  at a temperature greater than or equal to 1000 C and is maintained at this temperature, this results in a vaporization of the water contained in the mass and a release of the gases trapped in it. The vaporization and the evolution of gas gives

  spark or scattered microdischarge.

  through the mass 2 as in the achievement of

  Induction heating and the accumulation of

  are performed with good efficiency because the rare earth concentrate has a dielectric constant

  high Sparks or microdiscs are totally

  in the mass 2 and without raising its temperature so much

  ture, facilitate dissociation and reduction of the concentrate with localized high thermal energy created by

  discharges and in the presence of the reaction electrolyte.

  In both embodiments of Figures 1 and 2, the mass 2 itself does not have a temperature so high if considered as a whole It follows that the amount of fog and gas released, toxic and difficult to

  In this way, it is possible to choose conditions that

  much less severe reaction to the treatment of these gases and fogs and use a less

  simpler than in conventional processes.

  Depending on the type of electrolyte used, you can also

  provide a higher energy quantity and thereby heat the mass 2 to a higher temperature, from 300 to 300 ° C or more, possibly up to 10000 ° C,

  so as to obtain a higher reaction rate.

  Thus, by using an alkaline electrolyte such as caustic soda, which can greatly reduce toxic gases such as S Ox, a larger energy supply can be used to increase the speed of the reactions.

Example t

  The liquid electrolyte is an aqueous solution containing% by weight of sodium hydroxide (NaOH) and is mixed

  each of the various rare earth concentrates described above.

  afterwards with this liquid electrolyte, according to a report in

  volume of 12 The concentrate is in the form of

  particles having a particle size of 50 μm The mixture is

  subjected to induction heating as described above.

  and there are tiny blue or blue-green discharges throughout the mixture. It has been found that: 1) when the rare earth concentrate is monazite or xenotime (RP 04), a hydroxide is obtained. rare earth (R (OH) 3) and sodium phosphate (Na 2 PO 4); we do not see

no release of toxic gases.

  2) when the rare earth concentrate is bastnesite, a rare earth hydroxide (R (OH) 3), fluoride is obtained

  of sodium (Na F) and sodium carbonate (Na 2 C 03).

  serve no release of toxic gases.

  3) when the rare earth concentrate is a mixture of monazite (4 parts) and bastnesite (6 parts), we obtain

  hydroxide of rare tertes (R (OH) 3), sodium phosphate

  dium (Na 2 P 04), sodium fluorine (Na F) and sodium carbonate (Na 2 CO 3) No release of toxic gases was observed. In each of the cases considered above, the yield reaches 90 to 95% or more. Thus, we measure at the origin

  the content of rare earth elements in each concentration

  After induction heating, the rare earth hydroxide deposit is collected for filtration and washing with water at 100 ° C. The washed rare earth hydroxide is then treated with 5% hydrochloric acid solution at 100 ° C. C

  for 40 minutes to obtain a solution after adjusting

  from 5.8 to 6.0, the solution is released.

  of the deposit containing thorium hydroxide, yttrium compounds and a small amount of rare substances, and is condensed by boiling. Then, by drying the concentrate, the rare earth chloride is obtained (RC 13 The alternative solution can be neutralized with sodium hydroxide to obtain a deposit containing the rare earth hydroxide. This process provides the rare earth material yield of 92 to 93%. also a 92 to 93% yield of substance

rare earths.

Example II

  The liquid electrolyte is an aqueous solution of ammonium chloride (NH 4 Cl), which is mixed with a mixed rare earth concentrate containing monazite (4 parts) and bastnisite (6 parts). that by induction heating this mixture and subjecting these particles to

  tiny electric discharges, we obtain hydro-

  rare earth oxides (R (OH) 3) and rare earth chlorides (RC 13) and in addition toxic gases such as fluorine (F 2), hydrogen fluoride (HF), chlorine (Cl 2) and fluoride

  ammonia NH 4 F) with other toxic gases in small quantities.

  among others NH 4 HF 2, PC 13 and POC 1 At the same time, it

  is also produced phosphoric acid.

Example III

  The liquid electrolyte is an aqueous solution of sodium chloride which is mixed with a mixture of monazite and bastn 5 site. It has been found that by induction heating this mixture and subjecting these particles to tiny electrical discharges, we obtain R (OH) 3 and RC 13 with small amounts of toxic gases, among others Na F, C 12, PC 13 and POC 1 Simultaneously, sodium phosphate Na 3 PO 4 is also produced

Example IV

  The liquid electrolyte is sulfuric acid (H 2504) or an aqueous solution of acid which is mixed with a mixture of monazite and bastnesite. It has been found that by induction heating this mixture and subjecting these particles to tiny electric discharges, we obtain rare earth sulfates (R 2 (504) 3), phosphoric acid (H 3 P 04)

  and toxic gases, especially F 2, HF and S Ox.

Example V

  The liquid electrolyte is an aqueous solution of sodium carbonate (Na CO 3) which is mixed with a mixture of monazite

  and it has been found that by inductive heating

  this mixture and subjecting the particles to

  electrical discharges, hydroxides of

  rare earths (R (OH) 3) and sodium phosphate (Na 3 PO 4).

  No release of toxic gases is observed.

Example VI

  The liquid electrolyte is an aqueous solution of potassium hydroxide (KOH) and is mixed with a monazite mixture

  and bastn Ssite It has been found that by inductive heating

  this mixture and subjecting the particles to

  electrolytes, we obtain rare earth hydroxides (R (01) 3), potassium phosphate (K 3 P 04), potassium fluoride (KF) and potassium carbonate (K 2 C 03).

  does not observe any release of toxic gases.

Example VII

  A rare earth ore concentrate consisting of% monazite and 70% bastnesite contains 60% by volume of rare earth complexes, calculated in terms of rare earth oxides (R 203). The concentrate is ground into particles.

  so that 99% of them have a dimension of 75 lim.

  In proportion by weight, 2 parts of particles are mixed with one part of caustic soda and 0.4 part of water of

  that a molecule of the rare earth concentrate is pre-

  sense for 3 molecules of caustic soda in the mixture

and suspended in the solution.

  The slurry mixture weighing 60 g is formed into individual discs each having a diameter of 30 mm and a thickness of 6 to 8 mm. These discoldal masses are loaded in a high frequency induction heating furnace, as can be seen generally in FIG. 1, and are heated therein by a high frequency induction heating current, having a frequency of 40 kl / z, passing through a winding 6 for a period of 10 minutes at a heating rate of 6.4 Kcal / minute The deposit is washed 5 times with water at 1000 C or at room temperature, it is

  then dried and 36-, 5 g of hydroxide of rare tertes.

  The latter is dissolved in an aqueous solution of 300 ml by volume containing 35 to 40% by weight of hydrogen chloride

  and is heated at a temperature of 1050 C for 10 minutes.

  After repeating this acid solubilization 3 times, the deposit obtained is dehydrated to obtain 0.8 g of chloride.

rare earth.

Example VIII

  A mass of 83 g of the slurry mixture, as in Example VII, is induction heated by being exposed to a microwave beam at a frequency of 2450 MHz from a one-magnetron. heating rate of 6.4 Kcal / minute for 15 minutes Then, as in Example VII, the mass treated is washed 5 times, subjected to filtration and

  then dried; 57.5 g of rare earth hydroxide are obtained.

  When it is dissolved, for 10 minutes, with a

  400 ml aqueous solution containing 36% by weight of chlorine

  hydrogen is heated to 1051 ° C, a residue of

  1.8 g constituted by a rare earth chloride.

  X-ray analysis of the rare earth hydroxide scrap obtained in Examples VII and VIII shows that they contain practically no trace of oxides of earth

  rare, indicating that the oxides have been practically complete

reduced to the hydroxide.

Claims (10)

claims   A process for treating a rare earth ore or pulverized concentrate, characterized in that a) the rare earth ore or concentrate is mixed with an aqueous solution of an electrolyte to form a muddy mass of the mixture; and b) inductively heating the mass to facilitate reduction of the ore or concentrate by the electrolytes. 2 Process according to claim 1, characterized in that   the mass is heated by passing an electric field through   than high frequency, of frequency between 50 Hz and   1-Ok Hz, created by electric induction.   3 Process according to claim 1, characterized in that said mass is heated by exposing it to a microwave beam with a frequency of between 300 M 4 z and 300 GHZ.   Process according to claim 1, characterized in that the ore or concentrate contains a rare earth compound in the form of an oxide of at least one element of rare earth.   Process according to claim 1, characterized in that the rare earth ore or concentrate is at least one ore selected from the group consisting of monazite,   bastnâsite, gadolinite and xenotime.   Process according to claim 1, characterized in that the rare earth ore or concentrate is a mixture of monazite and bastnâsite.   Process according to Claim 1, characterized in that the electrolyte is at least one substance selected from   group consisting of the following products:   sium, ammonia, ammonium chloride, sodium chloride, sulfuric acid, sodium carbonate, sodium hydroxide and potassium hydroxide. Process according to claim 1, characterized in that   the electrolyte contains at least one alkaline compound.   Process according to claim 8, characterized in that   the alkaline compound is sodium hydroxide.   Method according to claim 1, characterized in that   the ore or rare earth concentrate sprayed has a   nullometry between 37 and 150 Vi m.   11 Apparatus for treating a rare earth ore or concentrate, characterized in that it comprises: a treatment tank (1), support means (4, 5) arranged in the tank to retain a muddy mass (2) ) formed by the ore or the concentrate mixed with an aqueous solution of an electrolyte, and means for inductively heating this mass to facilitate the reduction of the ore or   rare earth concentrate by the electrolyte.   12 Device according to claim 11, characterized in that the heating means comprise a winding (6) arranged to surround the mass and a current source (7) for passing a high frequency electric current, a frequency between 50 Hz and 100 k Hz across   winding to inductively heat the mass.   13 Apparatus according to claim 11, characterized in that the heating means comprise a microwave tube (15) for exposing the mass to a microwave beam with a frequency between 300 M Hz and 300 G Hz for heat the mass by induction.