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WO1983000142A1 - Production d'oxyde de magnesium - Google Patents

Production d'oxyde de magnesium Download PDF

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Publication number
WO1983000142A1
WO1983000142A1 PCT/AU1982/000102 AU8200102W WO8300142A1 WO 1983000142 A1 WO1983000142 A1 WO 1983000142A1 AU 8200102 W AU8200102 W AU 8200102W WO 8300142 A1 WO8300142 A1 WO 8300142A1
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Prior art keywords
magnesium
crude
iron
magnesium oxide
carbon dioxide
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PCT/AU1982/000102
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English (en)
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Scientific And Industrial Research ... Commonwealth
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Commonwealth Scientific and Industrial Research Organization CSIRO
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Commonwealth Scientific and Industrial Research Organization CSIRO
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Priority to AU85810/82A priority Critical patent/AU8581082A/en
Publication of WO1983000142A1 publication Critical patent/WO1983000142A1/fr
Anticipated expiration legal-status Critical
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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
    • C01F5/00—Compounds of magnesium
    • C01F5/02—Magnesia
    • C01F5/06—Magnesia by thermal decomposition of magnesium compounds
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/60—Particles characterised by their size
    • C01P2004/61—Micrometer sized, i.e. from 1-100 micrometer

Definitions

  • This invention relates to an improved method of producing high grade magnesium oxide (magnesia) from crude magnesite or from other crude magnesium-containing compounds, such as magnesium hydroxide, magnesium carbonate, basic magnesium carbonate etc., all of which can be thermally decomposed (calcined) to crude magnesium oxde.
  • Magnesium oxide is used for making furnace bricks for roasting and smelting furnaces, as well as in numerous other applications.
  • the purity of the magnesium oxide used to make the furnace bricks is critical.
  • the iron, aluminium, calcium, silicon and boron contents must be below specified limits.
  • grades of magnesium oxide used for making furnace bricks each grade having its own specification limits.
  • the magnesium-containing starting material is normally heated under controlled conditions to induce decomposition of the magnesium-containing compound to crude magnesium oxide.
  • High grade magnesium oxide can be formed by removing the impurities by physical beneficiation techniques and/or by dissolving the crude magnesium oxide, purifying the resultant solution, precipitating or crystallizating a magnesium compound from the purified liquor, and thermally decomposing (calcining) the magnesium salt to magnesium oxide.
  • Proposed leachants or dissolving media include hydrochloric acid, nitric acid, sulphuric acid, and aqueous carbon dioxide (carbonic acid).
  • the starting magnesium containing compound might be crude magnesite which contains iron carbonate (siderite) in solid solution with the
  • magnesium carbonate magnesium carbonate
  • the product is crude magnesium oxide with iron oxide in solid solution with the magnesium oxide.
  • acid gases are evolved and these must be collected, purified and reconverted to a form suitable for recycling to the dissolution circuit.
  • aqueous slurry of crude magnesium oxide reacts readily with carbon dioxide to form soluble magnesium bicarbonate.
  • the latter is stable only in the presence of excess carbon dioxide. If the excess carbon dioxide is removed by air sparging and/or heating, an insoluble hydrated magnesium carbonate or basic magnesium carbonate is precipitated, the nature of the product depending upon the slurry temperature.
  • the insoluble hydrated magnesium carbonate or basic magnesium carbonate is readily thermally decomposed (calcined) to magnesium oxide, carbon dioxide and water vapour. After removing the water vapour, the carbon dioxide can be led directly back to the dissolution (leaching) circuit.
  • the recycled carbon dioxide is the leachant for fresh slurry of crude magnesium oxide introduced into the leaching circuit. Because a complex leachant recovery circuit is not required, dissolution with carbon dioxide has a significant advantage compared with dissolution with hydrochloric acid, nitric acid or sulphuric acid.
  • ferric compounds are not normally soluble at pH values greater than 3 or 4, it was found that when an aqueous slurry of crude magnesium oxide, derived from the crude magnesium-containing compound, is dissolved by the use of carbon dioxide, considerable and undesirable iron dissolution also occurs, particularly when the crude magnesium compound contains iron oxide or iron carbonate present in solid solution. Unless the iron dissolved during dissolution of the crude magnesium oxide is removed, it will contaminate the hydrated magnesium carbonate or basic magnesium carbonate precipitated when the excess carbon dioxide is removed by air sparging and/or heating. As a consequence, the magnesium oxide derived from the precipitated hydrated magnesium carbonate or basic magnesium carbonate by thermal decomposition (calcination), will also be contaminated by iron oxide. Until now, no adequate means of removing such iron, when present, has been available.
  • the thermal decomposition or calcination of magnesium- containing compounds to magnesium oxide is a well understood art - see for example R.C. Mackenzie, editor, Differential Thermal Analysis, Volume 1, Fundamental Aspects, Academic Press, London, 1970.
  • control of the thermal decomposition (calcination) conditions is of importance when leaching an aqueous slurry of crude magnesium oxide, derived from the crude magnesium-containing compound, with carbon dioxide.
  • the calcination conditions control the surface area of the crude magnesium oxide which in turn controls the rate at which the aqueous slurry of the crude magnesium oxide reacts with the carbon dioxide. It is commercially desirable to achieve the highest practical reaction rate.
  • the amount of iron dissolved, while reacting the aqueous slurry of crude magnesium oxide with the carbon dioxide also depends on the dissolution or leaching conditions, particularly the leaching temperature and the time between the formation of the aqueous slurry of crude magnesium oxide and the introduction of the carbon dioxide.
  • the invention provides a process for preparing substantially pure magnesium oxide from crude magnesium-containing compounds which have an iron impurity, which process comprises calcining the crude magnesium- containing compounds to crude magnesium oxide, forming a slurry of the crude magnesium oxide and reacting it with carbon dioxide, removing the unreacted solid from the iron- containing pregnant magnesium bicarbonate solution so produced and adding a water-soluble aluminimum salt to the pregnant solution to precipitate out the iron, air sparging and/or heating the solution after removal of the precipitated iron to produce a precipitate of hydrated magnesium carbonate and/or basic magnesium carbonate, separating the precipitate and decomposing it to produce substantially pure magnesium oxide.
  • the aluminimum salt is added to the slurry prior to or during the reaction of the slurry with carbon dioxide.
  • the calcining of the crude magnesium-containing compounds having the iron impurity is effected by heating the crude magnesium-containing compounds to a temperature and for atime such that from 85% to 95% by weight of the magnesium present in the crude magnesium-containing compounds are transformed into crude magnesium oxide with a high surface area.
  • the slurry of crude magnesium oxide is reacted with the carbon dioxide at a temperature within the range of 10°C to 45°C using a slurry agitation rate and reaction time sufficient to ensure that more than 95% of the magnesium present as magnesium oxide has reacted to form soluble magnesium bicarbonate.
  • the crude magnesium oxide is dry ground (e.g. to such a size that 100% passes through a 400 micron mesh and 80% passes through a 150 micron mesh) prior to slurrying with water and the pulp density is adjusted to a value in the range of 2% to 5% solids with recycle liquor having a magnesium content of less than 0.5 gpl and preferably less than 0.2 gpl.
  • the reaction with carbon dioxide may be effected at a partial pressure within the range of 175 kPa to 700 kPa, the time taken between the formation of the slurry and the contact of the latter with the carbon dioxide being less than 0.5 hour
  • the preferred aluminium salt employed to precipitate out the iron is aluminium sulphate. Precipitation may be carried out under a carbon dioxide partial pressure of 175 kPa to 700 kPa, the amount of aluminium sulphate or other water-soluble aluminium salt being such that the [Fe x 100/Mg] concentration ratio of the resultant solution is in the range of 0.0 to 0.2.
  • the process may be effected in such a manner that the carbon dixide evolved during any of the process steps is recovered, purified, compressed and recycled to the leaching circuit.
  • Figure 1 is a flow chart illustrating the process steps of the invention in which the iron impurity is removed from the pregnant liquor, which has been separated from unreacted solid material prior to the precipitation of hydrated magnesium carbonate or basic magnesium carbonate, and
  • FIG. 2 is a flow chart illustrating the process steps of the invention in which the iron impurity is removed simultaneously with the dissolution of the magnesium, as magnesium bicarbonate, from the crude magnesium oxide.
  • the temperature and time of calcination are controlled by the composition of the feed material. Calcination should be carried out at as low a temperature and for as short a time as is consistent with the optimum decomposition of the crude magnesite to crude magnesium oxide, the latter having as high a surface area as possible.
  • optimum calcination conditions are of the order of 700°C for one hour, the actual time depending to some extent on the paifticle size of the feed material.
  • the calcination conditions should be such that about 90% of the crude magnesite has been thermally decomposed to crude magnesium oxide.
  • Calcination at a lower temperature or for a substantially shorter time results in a reduced amount of crude magnesite that has been thermally decomposed to crude magnesium oxide.
  • Calcination at higher temperatures or for substantially longer times results in over calcination; in particular the surface area of the crude magnesium oxide is substantially reduced such that it reacts very slowly with carbon dioxide when it is slurried with water and contacted with the carbon dioxide.
  • the hot, crude magnesium oxide from the calcination circuit (2) is allowed to cool to room temperature and then passed to a grinding circuit (3) where its particle size is reduced by dry grinding to a size suitable for leaching, preferably 100% passing through a 400 micron mesh and 80% passing through a 150 micron mesh. Grinding must be carried out in the dry state since if wet grinding is carried out, there is a reaction between the crude magnesium oxide and the water (slaking) which affects the amount of iron dissolved in the subsequent leaching stage (4).
  • the ground crude magnesium oxide is slurried with water just before it is introduced into the leaching circuit (4).
  • the reaction between the crude magnesium oxide and the water used to slurry the former so that it can be introduced into the autoclaves, that is, the slaking reaction, is exothermic, that is, it generates heat.
  • the amount of iron that is dissolved in the subsequent leaching step is affected by the temperature of the slurry and the time before it is contacted with the carbon dioxide.
  • An increase in the slurrying time and an increase in the slurry temperature both lead to an increase in the amount of iron dissolved in the leaching step.
  • the slurry temperature should be maintained at the leaching temperature, that is, in the range 10°C to 45°C while the slurring time should be kept below 30 minutes.
  • Leaching is carried out in a closed reaction vessel (4) with suitable inlets for feed slurry, water (make-up and/or recycle-liquor) and carbon dioxide. Suitable outlets for sampling and slurry discharge are also necessary.
  • the reaction vessel is fitted with a suitable agitation system and baffled such that there is adequate mixing and dispersion of the carbon dioxide throughout the slurry.
  • Leaching conditions time, temperature, carbon dioxide partial pressure, pulp density and initial leachant composition
  • solubility of magnesium bicarbonate the product of the reaction between the slurry of crude magnesium oxide and the carbon dioxide.
  • the amount of iron that is simultaneously dissolved is also affected by the leaching conditions, particularly the temperature, pulp density and the initial leachant composition.
  • solubility of magnesium bicarbonate increases with decreasing temperature, it may be considered preferable to leach at as low a temperature and at as high a pulp density as possible, say of the order of 5°C and 5% solids respectively.
  • the amount of iron that is dissolved under these conditions is excessive.
  • the amount of iron that is dissolved decreases as the leaching temperature and pulp. density are increased and decreased respectively.
  • Preferred leaching temperatures and pulp densities are in the range of 10°C to 45°C and 2% solids to 5% solids respectively.
  • the preferred pulp density should be such that the solubility limit of the magnesium bicarbonate, formed by the interaction of the magnesium oxide with the carbon dioxide, is not exceeded at the operating carbon dioxide partial pressure and leaching temperature.
  • the preferred leaching time is such that greater than 95% of the available magnesium, present as magnesium oxide, reacts to form soluble magnesium bicarbonate.
  • the preferred leaching time depends upon the leaching temperature, carbon dioxide partial pressure, pulp density and agitation rate and also on the calcination conditions used to thermally decompose the crude magnesite to crude magnesium oxide.
  • the preferred leaching time should be less than two hours and preferably l ⁇ ss than one hour.
  • the preferred carbon dioxide partial pressure which is dependent upon the leaching temperature, should be as low as . practical so as to avoid the use of expensive and complex high pressure reaction vessels (autoclaves).
  • the preferred carbon dioxide partial pressure is in the range 175 kPa to 700 kPa.
  • the preferred magnesium content of the recycle liquor is in the range 0.0 gpl to 0.5 gram per litre (gpl), preferably in the range 0.0 gpl to 0.2 gpl.
  • any unreacted solid material is separated from the magnesium bicarbonate slurry by solid/liquid separation techniques (5).
  • the preferred solid/liquid separation technique is pressure filtration, using carbon dioxide as the pressurization atmosphere.
  • the clarified iron-containing magnesium bicarbonate solution issuing from the solid/liquid separation circuit (5) is transferred to a further reaction vessel (6) where the iron is removed by precipitation on addition of aluminimum sulphate or another water-soluble aluminium salt or a solution of such a salt.
  • Precipitation is carried out under a carbon dioxide partial pressure similar or identical to that used in the leaching circuit (4), that is, in the range 175 kPa to 700 kPa. In this way, the possibility of the undesirable precipitation of hydrated magnesium carbonate and/or basic magnesium carbonate is avoided.
  • the amount of aluminium sulphate added is such that the soluble iron content of the resultant slurry is below the desired level.
  • the preferred soluble iron content of the resultant slurry is such that the [Fe x 100/Mg] concentration ratio of the clarified liquor obtained from the slurry formed on addition of the aluminium sulphate to precipitate the iron is less than 0.2 and preferably less than 0.1
  • the corresponding iron contents are 0.020 and 0.010 gpl respectively, or 20 ppm and 10 ppm respectively.
  • Precipitation by addition of aluminimum sulphate, of the iron present in the clarified magnesium bicarbonate solution takes place rapidly, so that the preferred retention time in the precipitation vessel (6) is in the range 5 minutes to 10 minutes.
  • the slurry of the magnesium bicarbonate solution and the magnesium-iron-aluminium precipitate is passed to a pressure filtration circuit (7) and the magnesium-iron- aluminium precipitate removed.
  • Carbon dioxide is used as the pressurizing atmosphere to prevent precipitation of hydrated magnesium carbonate and/or basic magnesium carbonate.
  • the iron-free magnesium bicarbonate solution issuing from the pressure filtration circuit (7) is fed to a precipitation vessel (8) where the magnesium is precipitated by air injection (sparging) and/or heating such that the carbon dixoide content of the iron-free magnesium bicarbonate solution, in the form of dissolved carbon dioxide and/or as the carbonate anion and/or as the bicarbonate anion, is rapidly reduced so that hydrated magnesium carbonate (nesquehonite, MgCO 3 .3H 2 O) and/or basic magnesium carbonate (hydromagnesite, Mg 5 (CO 3 )4(OH) 2 .4H 2 O) is preciptated.
  • the rate at which the magnesium is precipitated depends upon the temperature of the pure magnesium bicarbonate solution and the rate of air injection.
  • the rate of precipitation is increased by increasing the solution temperature and by increasing the rate of air injection.
  • the temperature of precipitation and rate of air injection should be such that the magnesium content of the resultant slurry solution is reduced to less than 0.5 gpl and preferably less than 0.2 gpl within 1 hour to 2 hours.
  • the rate of air injection should not be too high since the carbon dioxide evolved during precipitation must be collected, purified and compressed (11) before being utilized in the leaching circuit (4). If the rate of air injection during precipitation (8) is too high, the carbon dioxide will be excessively diluted with air, leading to complications with the collection, purification and compression circuit (11).
  • the temperature at which precipitation takes place (8) should not be too high since the bulk density of the precipitate formed decreases with increasing precipitation temperature.
  • the precipitated hydrated magnesium carbonate (nesquehonite) and/or basic magnesium carbonate (hydromagnesite) and the magnesium oxide derived from it should have as high a bulk density as possible.
  • the preferred precipitation conditions (8) are in the ranges of 20°C to 45°C and 1 hour to 2 hours respectively.
  • the slurry of precipitated hydrated magnesium carbonate and/or basic magnesium carbonate (only the former is indicated in Figure 1) is transferred to a conventional solid/liquid separation circuit (9) where the solid hydrated magnesium carbonate and/or basic magnesium carbonate is separated from the solution.
  • Counter-current decantation and rotary vacuum filtration are suitable techniques for carrying out this solid/liquid separation.
  • the separated solution which contains 0.0 gpl to 0.5 gpl magnesium and preferably 0.0 gpl to 0.2 gpl magnesium, forms the recycle liquor to the leaching circuit (4).
  • the solid hydrated magnesium carbonate and/or basic magnesium carbonate is transferred to a suitable furnace (10) where it is thermally decomposed (calcined) to magnesium oxide, water vapour and carbon dioxide. Evolution of water vapour and of carbon dioxide may be carried out in two essentially separate stages, so that carbon dioxide recovery is more readily performed.
  • the water vapour is removed from the off-gases, and after purification and compression (11), the carbon dioxide is returned to the leaching circuit (4).
  • the optimum calcination temperature is in excess of 600°C, that is, above the decomposition temperature of the hydrated magnesium carbonate and/or basic magnesium carbonate. Subsequent heating so as to ensure that the product has a suitably high bulk density for furnace brick manufacture usually requires calcination in the range 1600°C to 1800°C, with or without intermediate briquetting or pressing of the magnesium oxide produced at 600°C.
  • the magnesium- iron-aluminium compound separated from the pressure filtration circuit (7) is passed to a reaction vessel (12).
  • the magnesium-iron-aluminium compound is reacted with sulphuric acid, the amount of acid added being sufficient to produce a slurry pH m the range 3.5 - 4.5. Under these conditions the magnesium and aluminium components of the magnesium-iron-aluminium compound dissolves.
  • the iron component does not dissolve and is removed by conventional filtration means (13).
  • the iron-free magnesium-aluminium sulphate solution is then used, together with any necessary aluminium sulphate, to precipitate the iron from fresh iron-containing magnesium bicarbonate liquor in reaction vessel (6) as described above.
  • Figure 2 which illustrates the second method of ensuring that the final product has an iron content within specification limits, is essentially the same as that described above and illustrated by Figure 1, except that the aluminium sulphate or other water-soluble aluminium salt is added to the leaching circuit rather than to the clarified pregnant liquor.
  • the second method consists of a crushing circuit (1), calcination circuit (2) and grinding circuit (3) which are the same as those described above and shown in Figure 1,
  • Leaching of the crushed, ground calcined crude magnesite is carried out as previously described in a suitable reaction vessel with the exception that the aluminium sulphate or other water-soluble aluminium salt or a solution of aluminium sulphate or other salt is also added to the leaching vessel (4).
  • the leaching conditions are identical to those described above. Removal of unreacted solid, which in this case includes the magnesium-iron-aluminium compound that precipitates, is carried out by pressure filtration using carbon dioxide as the pressurizing atmosphere (5).
  • the second embodiment of the invention has the advantage over the first embodiment, as shown in Figure 1, in that the former requires one less reaction vessel and one less solid/liquid separation circuit - (6) and (7) in Figure 1.
  • both embodiments result in the formation of a pregnant magnesium bicarbonate solution low in iron and from which high grade magnesium oxide can be recovered.
  • leaching conditions and the amount of aluminium salt used to precipitate any soluble iron it is possible to form a range of magnesium oxide products with iron contents of 0.05% or even lower.
  • This example shows the effect of the calcination conditions on the rate at which the crude magnesium oxide reacts with carbon dioxide and the percentage dissolution of the crude magnesium oxide in a given time.
  • This example illustrates the effect of the temperature of the crude magnesium oxide slurry and the time between the formation of the slurry and when it is contacted with the carbon dioxide on the amount of iron dissolved during leaching.
  • the temperature and time are referred to as the slake temperature and slake time respectively.
  • the calcine used in this example was derived from the crude magnesite described in Example 1.
  • the calcine which contained 39.1% Mg, was formed at 700°C and was dry ground to 100% passing through a 150 micron mesh. Leaching was carried out in an autoclave at a temperature of 15.5°C, with a carbon dioxide partial pressure of 700 kPa, and agitator speed of 1200 rpm and using 30 g of calcine in one litre of magnesium and iron-free water. The results of these tests are given in Table 4.
  • This example illustrates the fact that provided the leaching temperature and pulp density are such that the solubility of magnesium bicarbonate is not exceeded, an increase in the carbon dioxide partial pressure results in a small increase in the amount of iron dissolved.
  • the calcine used is that described in Example 2; leaching was carried out with a 0.5 h slake time at the leaching temperature of 15.5°C using a 700 kPa carbon dioxide partial pressure, an agitation rate of 1200 rpm and a pulp density of 3% solids. The results of these tests are given in Table 7.
  • carbon dioxide partial pressure should be as low as possible. In this way the leaching equipment can be substantially simplified (unit 4 in Figures 1 and 2). In addition, the lower carbon dioxide partial pressure means that the load on the carbon dioxide purification and compression circuit (unit 11 in Figure 1 and unit 9 in Figure 2) is considerably reduced.
  • the data listed in Table 8 illustrate the effect of the agitation rate on the amount and rate of iron and magnesium dissolved.
  • the crude magnesium oxide calcine described in Example 2 was leached at 15.5°C after being slaked at 15.5°C for 0.5 h. A 3% pulp density and a carbon dioxide partial pressure of 700 kPa were used.
  • the agitation rate affects the rate of magnesium and iron dissolution as well as the amount of iron dissolved the higher the rate of agitation the higher the rate of magnesium and iron dissolution and the higher the amount of iron dissolved. It might be considered advantageous to use a relatively low agitation rate, say 900 rpm, such that the amount of iron that is dissolved is reduced. However, the rate of magnesium dissolution is substantially reduced at the same time so that the throughput of crude magnesium oxide calcine per unit time is also reduced.
  • This example shows the effectiveness of addition of aluminium sulphate to clarified pregnant iron-containing magnesium bicarbonate solution to remove the dissolved iron, that is, the method of iron removal indicated in Figure 1.
  • the tests were carried out by leaching separate samples of the crude magnesium oxide calcine described in Example 2 under the following conditions: 0.5 h slake at the leaching temperature of 15.5°C, 700 kPa carbon dioxide, 3% solids and agitation at 1200 rpm. After 2.5 hours the unreacted residue was removed and the clarified pregnant iron- containing magnesium bicarbonate solution was reacted with a known amount of aluminium sulphate, Al 2 (SO 4 ) 3. 16H 2 O, under a carbon dioxide partial pressure of 700 kPa, for one hour. The carbon dioxide partial pressure was used to prevent the precipitation of hydrated magnesium carbonate. The temperature and agitation rate were maintained at 15.5°C and 1200 rpm respectively. After the one hour interval, the magnesium and iron contents of the solution were determined.
  • Table 10 lists the magnesium and iron contents and the [Fe x 100/Mg] concentration ratio of the pregnant liquor before and after addition of the aluminium sulphate, as well as the magnesium and iron contents of the air dried nesquehonite and magnesium oxide products. The data clearly show that magnesium oxide with a very low iron content can
  • Nesquehonite and magnesium oxide were recovered from the pregnant magnesium bicarbonate solutions as described in Example 8. The results of these tests are given in Table 11. It can be seen that by increasing the amount of aluminium sulphate added the iron content of the pregnant magnesium bicarbonate solution, and hence of the nesquehonite and magnesium oxide derived therefrom, decreases quite significantly. It is also to be noted that for the same aluminium sulphate addition, the resulting iron content of the pregnant magnesium bicarbonate solution, nesquehonite and magnesium oxide respectively produced when the iron is removed during leaching (Example 9, Table 11) is less than that when the iron is removed from clarified pregnant magnesium bicarbonate solution (Example 8, Table 10). As in the previous example, magnesium oxide products wit even lower iron contents can be prepared by using leaching co ditions particularly leaching temperature, which reduces the amount of iron dissolved.
  • the aluminium sulphate could also be fed in as a solution to the leaching vessel.
  • This example encompasses the availability in the leaching vessel of a soluble aluminium salt during leaching.
  • the magnesium-iron-aluminium compound contained 15.2% MgO, 25.4%, Al 2 O 3 , 0.75% Fe 2 O 3 and 16.5% CO 2 . This was dissolved in the minimum volume of dilute sulphuric acid so that at the completion of reaction the resultant pH was 3.8. After clarification by vaccuum filtration the liquor was made up to 1 litre and contained 2.74 gpl magnesium. This liquor was used to slurry a fresh sample of crude magnes ium oxide which was processed as described in Example 2, test number 12. The results of this experiment are shown in Table 12.
  • test numoer 35 contained 34.5% HgO, 4.59% AI 2 O 3 , 4.23% Fe 2 O 3 and 25.5% CO 2 .
  • a sample of the solid was treated with dilute sulpnuric acid to yield a final slurry pH of 3.8.
  • the resultant solution after filtration contained 4.19 gpl magnesium and this corresponds to the dissolution of 67.1% of the magnesium contained in the solid.
  • This example describes the precipitation of hydrated magnesium carbonate (nesquehonite, MgCO 3 .3H 2 O) and/or basic magnesium carbonate (hydromagnesite, Mg 5 (CO 3 ) 4 (OH) 2 .4H 2 O) from pregnant iron-containing magnesium bicarbonate solutions.
  • the solutions were obtained as described in Example 2, test number 12.
  • the clarified pregnant iron- containing magnesium bicarbonate solutions were air sparged and heated as indicated in Table 14.
  • the soluble magnesium and iron contents of the slurries so produced were determined at suitable time intervals. Also listed in Table 14 is an estimate of the bulk density of the precipitated product that had been collected and air dried at ambient temperature for several days.
  • the rate of iron and magnesium precipitation is significantly greater at the higher precipitation temperatures. Since it has been previously shown that it is essential to have a recycle liquor, that is, the filtrate recovered after the separation of the hydrated magnesium carbonate and/or basic magnesium carbonate, which has a low magnesium content, preferably less than 0.2 gpl, it is clear that precipitation should be carried out at a moderate temperature, in the range 25°C to 45°C with air sparging.

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Abstract

Procédé de production d'oxyde de magnésium (magnésie) de grande pureté à partir de magnésite brute ou d'autres composés bruts contenant du magnésium tels que de l'hydroxyde de magnésium, du carbonate de magnésium, du carbonate basique de magnésium etc., toutes ces substances pouvant être décomposées thermiquement en carbonate de magnésium brut, et contenant des impuretés sous forme de fer. Le procédé consiste à calciner les composés bruts contenant du magnésium de manière à obtenir un oxyde de magnésium brut (2), à former une boue d'oxyde de magnésium brut (3) et à faire réagir la boue avec de l'anhydride carbonique (4). La substance solide n'ayant pas réagi est enlevée de la solution saturée de bicarbonate de magnésium contenant du fer en (5). Un sel d'aluminium soluble dans l'eau est ajouté à la solution saturée (6) pour précipiter le fer (7) et l'on fait barboter (8) la solution et/ou on la chauffe après la clarification pour produire un précipité de carbonate de magnésium hydraté et/ou de carbonate de magnésium basique. Le précipité est séparé (9) et décomposé (10) pour produire de l'oxyde de magnésium sensiblement pur.
PCT/AU1982/000102 1981-07-02 1982-06-24 Production d'oxyde de magnesium Ceased WO1983000142A1 (fr)

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Application Number Priority Date Filing Date Title
AU85810/82A AU8581082A (en) 1981-07-02 1982-06-24 Magnesium oxide production

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Application Number Priority Date Filing Date Title
AUPE957481 1981-07-02
AUPE9574/81810702 1981-07-02

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WO1983000142A1 true WO1983000142A1 (fr) 1983-01-20

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Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1984003490A1 (fr) * 1983-03-07 1984-09-13 Commw Scient Ind Res Org Production d'oxyde de magnesium
GB2156793A (en) * 1984-04-02 1985-10-16 Commw Scient Ind Res Org Magnesium oxide production
RU2194012C1 (ru) * 2001-04-09 2002-12-10 Закрытое акционерное общество "Деловое сотрудничество" Способ получения порошка электротехнического периклаза
RU2211803C2 (ru) * 2001-06-26 2003-09-10 Закрытое акционерное общество "Экостар-Наутех" Способ получения оксида магния из природных рассолов
WO2018018137A1 (fr) * 2016-07-27 2018-02-01 Institut National De La Recherche Scientifique Production de magnésie à faible empreinte carbone
CN118750632A (zh) * 2024-06-06 2024-10-11 苏州智美达医疗科技有限公司 一种富氢抗氧化原料及其制备方法、氢分子抗菌敷料

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* Cited by examiner, † Cited by third party
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CN111606346A (zh) * 2020-06-05 2020-09-01 瀜矿环保科技(上海)有限公司 基于二氧化碳浸取的钙镁离子溶液制备碳酸钙镁的系统

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US2328286A (en) * 1943-08-31 Process of making heavy magnesium
US3320029A (en) * 1967-05-16 Method of preparing magnesia
DE2137573A1 (de) * 1971-07-27 1973-02-08 Oesterr Amerikan Magnesit Verfahren zur aufbereitung von magnesiumverbindungen
US4140745A (en) * 1977-01-10 1979-02-20 Advanced Mineral Research Ab Method of recovering magnesia from scrap brick

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WO1984003490A1 (fr) * 1983-03-07 1984-09-13 Commw Scient Ind Res Org Production d'oxyde de magnesium
GB2156793A (en) * 1984-04-02 1985-10-16 Commw Scient Ind Res Org Magnesium oxide production
RU2194012C1 (ru) * 2001-04-09 2002-12-10 Закрытое акционерное общество "Деловое сотрудничество" Способ получения порошка электротехнического периклаза
RU2211803C2 (ru) * 2001-06-26 2003-09-10 Закрытое акционерное общество "Экостар-Наутех" Способ получения оксида магния из природных рассолов
CN109790044A (zh) * 2016-07-27 2019-05-21 国家科学研究学院 低碳排放的氧化镁生产
KR20190033600A (ko) * 2016-07-27 2019-03-29 인스터? 내셔널 드 라 르세르슈 사이언티피크 저 탄소 풋프린트 마그네시아의 제조
WO2018018137A1 (fr) * 2016-07-27 2018-02-01 Institut National De La Recherche Scientifique Production de magnésie à faible empreinte carbone
AU2017301227B2 (en) * 2016-07-27 2022-04-07 Institut National De La Recherche Scientifique Production of low carbon footprint magnesia
US11401168B2 (en) 2016-07-27 2022-08-02 Institut National De La Recherche Scientifique Production of low carbon footprint magnesia
US20220332596A1 (en) * 2016-07-27 2022-10-20 Institut National De La Recherche Scientifique Production of low carbon footprint magnesia
KR102523562B1 (ko) 2016-07-27 2023-04-19 인스터?b 내셔널 드 라 르세르슈 사이언티피크 저 탄소 풋프린트 마그네시아의 제조
EP3490935B1 (fr) 2016-07-27 2023-06-07 Institut National De La Recherche Scientifique Production de magnésie à faible empreinte carbone
US12448298B2 (en) * 2016-07-27 2025-10-21 Institut National De La Recherche Scientifique Production of low carbon footprint magnesia
CN118750632A (zh) * 2024-06-06 2024-10-11 苏州智美达医疗科技有限公司 一种富氢抗氧化原料及其制备方法、氢分子抗菌敷料

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