WO2007115365A1 - Method of reducing calcia concentrations of green bayer process liquors - Google Patents
Method of reducing calcia concentrations of green bayer process liquors Download PDFInfo
- Publication number
- WO2007115365A1 WO2007115365A1 PCT/AU2007/000460 AU2007000460W WO2007115365A1 WO 2007115365 A1 WO2007115365 A1 WO 2007115365A1 AU 2007000460 W AU2007000460 W AU 2007000460W WO 2007115365 A1 WO2007115365 A1 WO 2007115365A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- apatite
- liquor
- red mud
- calcia
- filter
- Prior art date
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B25/00—Phosphorus; Compounds thereof
- C01B25/16—Oxyacids of phosphorus; Salts thereof
- C01B25/26—Phosphates
- C01B25/32—Phosphates of magnesium, calcium, strontium, or barium
-
- 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
- C01F7/00—Compounds of aluminium
- C01F7/02—Aluminium oxide; Aluminium hydroxide; Aluminates
- C01F7/04—Preparation of alkali metal aluminates; Aluminium oxide or hydroxide therefrom
- C01F7/06—Preparation of alkali metal aluminates; Aluminium oxide or hydroxide therefrom by treating aluminous minerals or waste-like raw materials with alkali hydroxide, e.g. leaching of bauxite according to the Bayer process
- C01F7/062—Digestion
- C01F7/0633—Digestion characterised by the use of additives
-
- 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
- C01F7/00—Compounds of aluminium
- C01F7/02—Aluminium oxide; Aluminium hydroxide; Aluminates
- C01F7/04—Preparation of alkali metal aluminates; Aluminium oxide or hydroxide therefrom
- C01F7/06—Preparation of alkali metal aluminates; Aluminium oxide or hydroxide therefrom by treating aluminous minerals or waste-like raw materials with alkali hydroxide, e.g. leaching of bauxite according to the Bayer process
- C01F7/0646—Separation of the insoluble residue, e.g. of red mud
-
- 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
- C01F7/00—Compounds of aluminium
- C01F7/02—Aluminium oxide; Aluminium hydroxide; Aluminates
- C01F7/46—Purification of aluminium oxide, aluminium hydroxide or aluminates
Definitions
- the present invention relates to a method of reducing calcia concentrations in liquors generated by the Bayer process for the production of alumina from ores of aluminium.
- the present invention relates to a method of reducing calcia concentrations in green Bayer process liquors.
- the Bayer process is widely used for the production of alumina from alumina- containing ores, such as bauxite.
- the process is initiated by contacting alumina- containing ores with recycled caustic aluminate solutions, at elevated temperatures, in a process commonly referred to as digestion.
- the slurry of insoluble red mud in sodium aluminate solution (green liquor) is passed through a series of pressure-reducing tanks (called blow- off tanks), where the solution is flashed to atmospheric pressure.
- the next step in the process is to separate the insoluble red mud from the sodium aluminate solution.
- Coarse material may be removed in crude cyclones called sand traps, while finer residue is settled in raking thickeners with the addition of synthetic flocculants.
- the red mud is taken as underflow from the thickeners, and then typically washed to recover caustic values and render such suitable for disposal.
- the overflow typically still contains finely divided red mud particulates, comprising iron oxides, iron hydroxides, silica and the like.
- the presence of these compounds in the final alumina product is highly undesirable and the settler overflow is often passed through one or more filters to remove such.
- the clarified solution is further cooled in heat exchangers, enhancing the degree of supersaturation of the dissolved alumina, and pumped into precipitators before being seeded with aluminium hydroxide to induce the precipitation of further aluminium hydroxide.
- the precipitated aluminium hydroxide is separated from the caustic aluminate solution, with a portion of the aluminium hydroxide being recycled to be used as seed and the remainder recovered as product.
- the remaining caustic aluminate solution is recycled for further digestion of alumina containing ore.
- the digestion process consumes caustic, which is typically replenished (at least in part) by the addition of lime.
- Calcia introduced by way of the lime may be precipitated as calcium carbonate.
- more effective causticisation may be achieved by the addition of an excess of lime, meaning calcia levels in the liquor increase.
- Elevation of green liquor (or slurry) calcia levels increases alumina stability, allowing filtration to occur at higher ratios of alumina to total caustic.
- apatite refers to one or more of a family of compounds based on hydroxylapatite Caio(PO 4 )6(OH)2, including fluorapatite (Caio(PO 4 ) 6 F 2 ), chlorapatite (Ca 10 (PO 4 ) 6 Cl2), hydroxylapatite (Cai 0 (PO 4 )6OH 2 ), carbonate-apatite, carbonate hydroxylapatite or carbonate fluorapatite.
- apatite can be described by the following formula Aio(XO 4 ) 6 (OH,F,CI) 2 .nH 2 O, wherein: A may be selected from Ba, Ca, Ce, K, Na, Pb, Sr, Y; X may be selected from As, P, Si, V, and CO 3 can be at least partially substituted for PO 4 .
- apatite encompasses mixtures containing apatite, including mixtures containing one or more apatites.
- a method of reducing the calcia concentration of a green Bayer process liquor containing calcia and phosphate comprising the step of:
- the apatite may be provided in the form of any compound having the general formula A 10 (XO 4 ) G (OH, F, Cl) 2 . nH 2 O, wherein: A may be selected from Ba, Ca, Ce, K, Na, Pb, Sr, Y; X may be selected from As, P, Si, V, and CO 3 can be substituted for PO 4 .
- A is Ca and Na and the apatite is provided at least predominantly in the form of a carbonate hydroxylapatite having the general formula Ca-io- ⁇ Na 2x / 3 (P ⁇ 4 ) 6-x (CO 4 ) ⁇ (OH) 2-x/3 .xH 2 O, where 0 ⁇ x ⁇ 3, or any mixture of such compounds.
- the apatite is provided in the form of Ca 7 Na 2 (CO 3 MPO 4 MH 2 O) 3 (OH).
- the scope of the invention should not be understood to be limited to carbonate hydroxylapatites, with non-carbonate hydroxylapatites such as Ca 5 (PO 4 ) 3 (OH) having been demonstrated to be effective.
- Apatite can typically be produced on-site at many Bayer process refineries, affording an additional advantage of the present invention.
- apatite may be prepared by the addition of a lime source and a phosphate source to a Bayer process liquor.
- the lime source may be provided in the form of slaked lime, tricalcium aluminate or press mud.
- the phosphate source and the Bayer process liquor may be provided together in the form of a high-phosphate Bayer process spent liquor. Residence times for the preparation of apatite are low, about 15-30 minutes, at temperatures of about 9O 0 C.
- the apatite so produced may be separated from the remaining solution before being utilised in the method of the present invention.
- a slurry of the apatite and supernatant solution may be utilised in the method of the present invention.
- the manner in which the apatite is prepared affects the efficacy of the apatite in the method of the present invention. Specifically, apatite prepared with a stoichiometric excess of phosphate is more effective, with greater excesses affording greater efficacies. Thus, in a preferred form of the invention, the apatite is prepared with a stoichiometric excess of phosphate.
- the residual phosphate concentration after apatite precipitation may cause other process complications.
- the apatite is prepared with less than 200% stoichiometric excess of phosphate, In a preferred form of the invention, the apatite is prepared with less than 100% stoichiometric excess of phosphate. In a preferred form of the invention, the apatite is prepared with less than 50% stoichiometric excess of phosphate.
- the efficacy of apatite in the method of the present invention diminishes with time.
- the quantity of apatite is preferably freshly precipitated, or at least freshly separated from the liquor from which it has been precipitated.
- the apatite is precipitated within 24 hours before it is contacted with the green Bayer process liquor in accordance with the method of the present invention.
- older apatite may be useful under favourable process conditions, such as high feed liquor calcia and phosphate concentrations.
- the apatite is precipitated within 8 hours before it is contacted with the green Bayer process liquor in accordance with the method of the present invention.
- the efficacy of precipitated apatite in the method of the present invention may be enhanced by exposing the quantity of apatite to a phosphate solution.
- the extent to which the activity is replenished has been found to be dependent on the concentration of the phosphate solution and the duration of the exposure, with longer exposure times and more concentrated phosphate solutions effecting greater replenishment.
- exposing aged apatite to a 9000 ppm phosphate solution for approximately 15 minutes will restore the activity of such to about one half to one third that of freshly precipitated apatite.
- the time for which the Bayer process liquor is in contact with the quantity of apatite has been found to affect the extent of the reduction in calcia concentration, with greater residence times typically resulting in greater calcia reduction. Accordingly, preferred residence times are derived from balancing calcia reduction with the effect of the method of the invention with other elements of the Bayer process.
- effective calcia reduction can be achieved using very short residence times, and in many preferred embodiments of the invention, the method can be implemented in conjunction with existing Bayer process steps without imposing a requirement of additional residence times.
- apatite doses of the order of 200 - 300 mg per kl_ of Bayer process liquor should be sufficient for a range of process conditions. Lower doses- may be possible under favourable process conditions, such as high feed liquor calcia and phosphate concentrations.
- the concentration of phosphate in the green Bayer process liquor has been found to affect the extent of reduction in calcia concentration, with higher concentrations effecting more significant and/or rapid reductions.
- high phosphate concentrations import process-related disadvantages that may outweigh any advantages achieved in calcia reduction.
- phosphate concentrations of green Bayer liquors vary considerably, from approximately 40ppm to in excess of 400ppm in high total alkali liquors.
- the calcia concentration of the green Bayer process liquor has been found to affect the extent of reduction in calcia concentration, with higher concentrations effecting more significant and/or rapid reductions.
- the temperature of the green Bayer process liquor has been found to affect the extent of reduction in calcia concentration, with higher temperatures effecting more significant and/or rapid reductions.
- varying the temperature of a Bayer process liquor is an energy intensive process and the economic advantage gained by varying the temperature of the Bayer process liquor to optimise the method of the present invention may be outweighed by the economic disadvantage of temperature elevation.
- the present invention works well at typical Bayer liquor filtration temperatures (100-105°C), but can be applied over a wide range of temperatures (7O 0 C and upwards). Although lower temperatures result in lower rates of calcium removal, these can be compensated by manipulating other process variables (e.g. apatite doses and sizing, feed * liquor calcium and phosphate concentrations, residence time).
- process variables e.g. apatite doses and sizing, feed * liquor calcium and phosphate concentrations, residence time.
- the sizing of the quantity of apatite has been found to affect the extent of reduction in calcia concentration, with smaller sizes effecting more significant and/or rapid reductions.
- the quantity of apatite is contacted with the green Bayer process liquor upstream from a solid- solution separation step. Examples of such forms of the invention are discussed below.
- the solid-solution separation step may provide a lower limit to the desired sizing of the quantity of apatite, in that it is highly desirable that the quantity of apatite be at least substantially separated from the solution in the solid-solution separation step.
- the quantity of apatite comprises apatite having a high surface area to volume ratio. Increasing the surface area of the quantity of apatite without decreasing sizing, or by at least not proportionately decreasing sizing, affords the advantages of more significant and/or rapid reductions in calcia concentration without attracting, or without attracting to a proportionate extent, the potential disadvantages in subsequent solid-solution separation.
- calcia may be present in a Bayer process liquor either as a by-product of a desirable process, such as causticisation, and/or may be added to achieve a desirable outcome such as alumina stabilisation during separation of residual solids (red mud) from green liquor.
- a desirable outcome such as alumina stabilisation during separation of residual solids (red mud) from green liquor.
- calcia introduced into the Bayer process liquor as a by-product of a desirable process may afford additional process benefits such as stabilisation of alumina during separation of residual solids (red mud) from green liquor.
- the method comprises the steps of:
- the steps of separating the red mud from the green liquor and contacting the green liquor with apatite may occur simultaneously.
- the step of separating the red mud from the green liquor comprises the step of passing the suspension of red mud in green liquor through a filter, and the step of contacting the green liquor with a quantity of apatite occurs immediately prior to the step of passing the suspension of red mud in green liquor through a filter.
- the step of separating the red mud from the green liquor comprises the steps of:
- the step of adding a quantity of calcia to the suspension of red mud in green liquor occurs before the step of passing the thickener overflow through the filter.
- the step of adding a quantity of calcia to the suspension of red mud in green liquor may occur after the step of passing the slurry of red mud and green liquor through one or more sand traps producing a second slurry of red mud and green liquor, the second slurry containing a lower proportion of red mud.
- the step of adding a quantity of calcia to the suspension of red mud in green liquor may occur after passing the second slurry through one or more thickeners, producing a thickener underflow of substantially red mud and a thickener overflow of substantially green liquor.
- the filter is a fixed-bed type filter, such as a sand filter.
- a fixed-bed type filter utilises a bed of at least substantially inert filtration medium, supported by a screen through which the liquor will pass.
- a bed of sand is supported by a metal screen, trapping red mud particles from the feed Bayer process liquor against sand particle surfaces in the bed, as the Bayer process liquor is pumped onto or into the bed (typically through holes in a rotating sparge), and passes through the interstices in the bed under the force of gravity.
- the steps of contacting the green Bayer process liquor with a quantity of apatite and passing the thickener overflow through a filter comprises combining the thickener overflow with the quantity of apatite then passing the combination through a filter.
- Fixed-bed type filters typically operate in cycles: eventually, sufficient particulate material accumulates on the substantially inert filtration medium to substantially decrease the efficiency of the filter. At this point, the filter is renewed, typically by back-washing. The time between filter renewals is typically referred to as a filter cycle.
- the reduction in calcia concentration is dependent on a range of factors, including residence time. In a preferred form of the invention, these factors are manipulated such that the desired reduction in calcia concentration is achieved within a residence time that is less than or equal to a single filter cycle. In this case, assuming constant feed conditions, the calcia drops occurring at any given time through each filter cycle should be proportional to the total mass of apatite dosed into the filter bed up to that time point.
- the filter is a cake-type filter.
- a cake-type filter is a filter in which filter aid solids (fine but readily-filterable, chemically inert, particulate solids), are pumped into the filter, to cover the filter leaves (mesh structures covered by open-weave filter cloths) with a filter cake, allowing passage of liquor through its pore structure, but retaining mud solids when green liquor is pumped through the filter, optionally under gravity or vacuum but usually (for green Bayer liquor filtration) under pressure (as in a Kelly filter).
- the filter aid solids can be pumped into the filter in either or both of the following ways:
- the step of contacting the green liquor with a quantity of apatite comprises the step of:
- the step of separating the red mud from the green liquor comprises the steps of:
- the method may comprise the prior additional step of:
- step of mixing the thickener overflow with a quantity of filter aid effects the step of contacting the green liquor with a quantity of apatite.
- the step of separating the red mud from the green liquor comprises the steps of:
- the method may comprise the prior additional step of:
- step of passing the thickener overflow through the layer of filter aid and the filter effects the step of contacting the green liquor with a quantity of apatite.
- the step of separating the red mud from the green liquor comprises the steps of:
- the apatite is of a similar sizing to the filter aid. That is, not so fine as to risk significant apatite contamination of filtrate and not so coarse as to lose the surface area needed for sufficient rates of calcia removal. Apatite falling mainly in the 5-15 micron size range would meet both of these criteria. Alternately, and as discussed above, larger particle sizes with increased surface area may be used.
- Apatite can typically be produced on-site at many Bayer process refineries, affording an additional advantage of the present invention.
- apatite may be prepared by the addition of a lime source and a phosphate source to a Bayer process liquor.
- the lime source may be provided in the form of slaked lime, tricalcium aluminate or press mud.
- the phosphate source and the Bayer process liquor may be provided together in the form of a high-phosphate Bayer process spent liquor. Residence times for the preparation of apatite are low, about 15-30 minutes, at temperatures of about 9O 0 C.
- the apatite so produced may be separated from the remaining solution before being utilised in the method of the present invention.
- a slurry of the apatite and supernatant solution may be utilised in the method of the present invention.
- source of phosphate shall be taken to include, without limitation, any form of phosphorus that provides an orthophosphate anion in Bayer process solutions.
- the method of the present invention permits the causticisation of a Bayer process solution and the simultaneous control of phosphate and calcium concentrations in the solution.
- Figure 1 is a schematic illustration of a Bayer process in which a cake-type filter is employed to separate residual solids (red mud) from green Bayer liquor, showing a first embodiment of the present invention
- Figure 2 is a schematic illustration of a Bayer process in which a fixed bed filter is employed to separate residual solids (red mud) from green Bayer liquor, showing a second embodiment of the present invention
- Figure 3 is a graph showing the effect of residence time of carbonate hydroxylapatite on calcia concentrations
- Figure 4 is a graph showing the effect of carbonate hydroxylapatite and filter aid concentrations on calcia concentrations
- Figure 5 is a plot showing the effect of carbonate hydroxylapatite on calcia concentrations in a continuous cake filtration process.
- Figure 6 is a plot showing the effect of carbonate hydroxylapatite and filter aid on calcia concentrations
- Figure 7 displays the results from a series of experiments in which carbonate hydroxylapatite was prepared in solutions containing a stoichiometric excess of phosphate
- Figure 8 displays the results from a series of experiments which demonstrate the effect of aging of the apatite on the efficacy of calcia removal.
- Figure 9 compares the amount of calcia removed from solution by the "refreshed" apatite with that of 1 day old & freshly prepared apatite.
- Bayer process liquor containing calcia and phosphate of the first embodiment is employed in the Bayer process in which an alumina-containing ore is dissolved in a caustic solution (10), providing a slurry of a red mud in a green liquor (12) containing phosphate.
- the slurry of a red mud in a green liquor containing phosphate is then passed through a thickener (14), producing a thickener underflow (16) of substantially red mud and a thickener overflow (18) of substantially green Bayer liquor.
- the thickener overflow (18) contains calcia.
- the calcia may have originated from any one or more of a number of possible sources. For example, by addition of lime or calcite (such as during a liquor causticisation process), from an elevated concentration of organic species in liquor, as a side- effect of other Bayer processes and/or by deliberate addition such as to stabilise alumina.
- the method of the first embodiment is employed in a Bayer process that utilises a cake-type filter (20).
- a quantity of carbonate apatite (22) in the form of Ca 7 Na 2 (C0 3 ) 3 (PO 4 ) 3 (H 2 O) 3 (0H) is combined with a first quantity of filter aid (24) to form a pre-coat (26) then applied as a layer to the cake-type filter (20).
- a second quantity of filter aid (28) is mixed with the thickener underflow (18) to form a slurry (30) of filter aid and thickener overflow.
- the amount of carbonate apatite (22) applied to the cake-type filter (20) depends on a range of factors, not least of which is the desired reduction (and rate of reduction) of calcia concentration, with larger amounts causing greater/more rapid reductions as discussed in the preceding general discussion of the invention. Further, and also as discussed in the preceding general discussion of the invention, the properties of the carbonate apatite (22), such as particle size and surface area, affect the amount required to achieve a given reduction in calcia concentration in a given time.
- the quantity of carbonate apatite (22) may originate from any source, conveniently the quantity of carbonate apatite (22) is generated as a by-product of another Bayer process step.
- the slurry (30) is then passed through the cake-type filter (20), thereby contacting green Bayer liquor in the form of the thickener overflow (18) present in the slurry (30) to the quantity of carbonate apatite (22) present in the layer applied to the cake-type filter (20). This induces the precipitation of further apatite and reduces the calcia concentration in the Bayer process liquor.
- the method of reducing the calcia concentration of a green Bayer process liquor containing calcia and phosphate of the second embodiment is applied in a Bayer process substantially similar to the Bayer process in which the method of the first embodiment is applied, and like numbers will be used to denote like parts.
- the Bayer process in which the method of the second embodiment is applied uses a fixed bed filter (32) in place of the cake-type filter.
- the thickener overflow (18) is mixed with a quantity of carbonate apatite (34) in the form of Ca 7 Na 2 (CO 3 ) S (PO 4 )S(H 2 O) 3 (OH), thereby contacting green Bayer liquor in the form of the thickener overflow (18) with the quantity of apatite, and the mixture held in a filter feed vessel (36) for a predetermined residence time before the mixture of carbonate apatite (34) and thickener overflow (18) is passed through the fixed bed filter (32).
- the amount of carbonate apatite (34) mixed with the thickener overflow (18) depends on a range of factors, not least of which is the desired reduction (and rate of reduction) of calcia concentration, with larger amounts causing greater/more rapid reductions as discussed in the preceding general discussion of the invention.
- the properties of the carbonate apatite (34), such as particle size and surface area affect the amount required to achieve a given reduction in calcia concentration in a given time.
- the properties of the thickener overflow (18) such as calcia concentration, phosphate concentration and temperature, affect the amount required to achieve a given reduction in calcia concentration in a given time.
- Table 1 and Figure 3 display the results from a series of experiments with carbonate hydroxylapatite - Ca 7 Na 2 (COs) 3 (PO 4 ) S (H 2 O) 3 (OH) - demonstrating the effectiveness of apatite in removing dissolved calcia from Bayer process solutions.
- Table 2 and Figure 4 display the results from a series of experiments in which carbonate hydroxylapatite was mixed with tricalcium aluminate (TCA), to demonstrate the effectiveness of the apatite in removing dissolved calcia from Bayer process solutions in the presence of filter aid.
- TCA tricalcium aluminate
- Neat green liquor solutions and green liquor solutions containing 0.5g TCA/L were heated to a temperature of 95°C.
- Carbonate hydroxylapatite was added to the solutions in doses of either 0.2g apatite/L or 1g apatite/L. The mixtures were mixed at temperature for either 1 minute or 10 minutes.
- Table 3 and Figure 5 display the results from a pilot scale experiment in which carbonate hydroxylapatite was mixed with tricalcium aluminate (TCA) as filter aid, to demonstrate the effectiveness of the apatite in removing dissolved calcia from Bayer process solutions in a continuous cake filtration process.
- TCA tricalcium aluminate
- Table 4 and Figure 6 display the results from a pilot scale experiment in which carbonate hydroxylapatite was mixed with tricalcium aluminate (TCA) and applied to the filter medium as a pre-filtration coating layer (pre-coat).
- TCA tricalcium aluminate
- Example 5 excess phosphate when apatite is prepared
- Figure 7 displays the results from a series of experiments in which carbonate hydroxylapatite was prepared in solutions containing a stoichiometric excess of phosphate, to demonstrate the effect of the excess phosphate on enhancing the activity of apatite with respect to calcia removal.
- Na 3 PO 4 .12H2O was dissolved in portions of neat spent liquor and the solutions heated to a temperature of 90°C.
- Slaked lime was added to the solutions in either stoichiometric quantities or in molar proportions such that the concentration of phosphate in solution was in either a 50% or 100% stoichiometric excess, with respect to the stoichiometry of the carbonate hydroxylapatite.
- the mixtures were reacted at temperature for 15 minutes before the apatite samples were separated from solution by filtration and washed.
- Neat green liquor solutions containing approximately 50ppm phosphate (expressed as P 2 O 5 ) were heated to a temperature of 95 0 C.
- the prepared carbonate hydroxylapatite samples were added to the solutions in doses of approximately 1g apatite/L. The mixtures were mixed at temperature for 10 minutes.
- Example 6 aged v fresh apatite
- Figure 8 displays the results from a series of experiments which demonstrate the effect of aging of the apatite on the efficacy of calcia removal.
- Example 7 reactivated apatite
- Figure 9 displays the results from a series of experiments which demonstrate that the calcia removal activity of old apatite can be regenerated by soaking apatite in solutions containing excess phosphate.
- Na 3 PO 4 .12H 2 O was dissolved in portions of neat spent liquor and the solutions heated to a temperature of 9O 0 C.
- Carbonate hydroxylapatite was added to the solutions in molar proportions such that the concentration of phosphate in solution was in a 100% stoichiometric excess with respect to the stoichiometry of the carbonate hydroxylapatite.
- the mixtures were reacted at temperature for 15 minutes before the apatite samples were separated from solution by filtration and washed.
- Neat green liquor solutions containing 40 - 50 ppm phosphate (expressed as P 2 O5) were heated to a temperature of 95°C.
- the "refreshed” carbonate hydroxylapatite samples were added to the solutions in doses of approximately 1g apatite/L.
- the mixtures were mixed at temperature for 10 minutes.
- Figure 9 compares the amount of calcia removed from solution by the "refreshed" apatite with that of 1 day oid & freshly prepared apatite.
- the data shown in Figure 9 demonstrate that the activity of old apatite, with respect to calcia removal, can be regenerated by soaking the carbonate hydroxylapatite in solutions containing excess phosphate.
- Examples 1 to 7 clearly evidence the efficacy of the method of the present invention in reducing calcia concentrations in Bayer process liquors.
Abstract
Description
Claims
Priority Applications (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AU2007236547A AU2007236547B2 (en) | 2006-04-07 | 2007-04-05 | Method of reducing calcia concentrations of green Bayer process liquors |
BRPI0709478-7A BRPI0709478A2 (en) | 2006-04-07 | 2007-04-05 | method for reducing bayer green liquor concentrations |
CN200780016077.6A CN101437758B (en) | 2006-04-07 | 2007-04-05 | Method of reducing calcia concentrations of green bayer process liquors |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AU2006901815A AU2006901815A0 (en) | 2006-04-07 | Method of Reducing Calcia Concentrations of Green Bayer Process Liquors | |
AU2006901815 | 2006-04-07 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2007115365A1 true WO2007115365A1 (en) | 2007-10-18 |
Family
ID=38580635
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/AU2007/000460 WO2007115365A1 (en) | 2006-04-07 | 2007-04-05 | Method of reducing calcia concentrations of green bayer process liquors |
Country Status (5)
Country | Link |
---|---|
CN (1) | CN101437758B (en) |
AU (1) | AU2007236547B2 (en) |
BR (1) | BRPI0709478A2 (en) |
RU (1) | RU2445264C2 (en) |
WO (1) | WO2007115365A1 (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FR2934852A1 (en) * | 2008-08-06 | 2010-02-12 | Alcan Int Ltd | IMPROVEMENT TO THE BAYER PROCESS FOR PRODUCTION OF ALUMINA TRIHYDRATE, SAID PROCESS COMPRISING A STEP IN WHICH THE SURSATURATED LIQUEUR IS FILTERED AT HIGH TEMPERATURE BEFORE DECOMPOSITION |
CN101264910B (en) * | 2008-04-25 | 2010-10-13 | 河南未来铝业(集团)有限公司 | Mother liquor evaporation seed addition method for aluminum hydroxide or aluminum oxide production technique by Bayer process |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN103717533A (en) * | 2011-08-08 | 2014-04-09 | 巴斯夫欧洲公司 | Method for producing ultrapure aluminum oxide by cleaning clay |
Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4016238A (en) * | 1975-08-29 | 1977-04-05 | Urbina Davalos Fernando | Process for the obtention of alumina and phosphate values by the alkaline decomposition of silica-containing aluminum phosphate ores |
JPS59156489A (en) * | 1983-02-28 | 1984-09-05 | Kurita Water Ind Ltd | Phosphate-contg. water disposal |
US4758412A (en) * | 1985-11-08 | 1988-07-19 | Rhone-Poulenc Specialites Chimiques | Production of rare earth hydroxides from phosphate ores |
US5534235A (en) * | 1995-09-05 | 1996-07-09 | Nalco Chemical Company | Polymers containing phosphonic acid groups for the treatment of red mud in the Bayer process |
WO2006081626A1 (en) * | 2005-02-03 | 2006-08-10 | Alcoa Of Australia Limited | Method for the causticisation of bayer process solutions |
Family Cites Families (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
SU814866A1 (en) * | 1979-05-07 | 1981-03-23 | Всесоюзный Научно-Исследовательскийи Проектный Институт Алюминиевой,Магниевой И Электродной Промышленности | Method of processing sulfide-sulfate mixture |
HU187654B (en) * | 1982-02-26 | 1986-02-28 | Ajkai Timfoeldgyar Aluminium | Process for reduction of damages in production of aluminium oxid of bayer system |
RU2188794C1 (en) * | 2001-03-28 | 2002-09-10 | Государственное унитарное предприятие Уральский научно-исследовательский химический институт с опытным заводом | Method of processing soda-sulfate mixture |
CN1297480C (en) * | 2002-03-05 | 2007-01-31 | 平顶山市汇源化学工业公司 | Process for removing organics from sodium Bayer process aluminate solution |
-
2007
- 2007-04-05 WO PCT/AU2007/000460 patent/WO2007115365A1/en active Application Filing
- 2007-04-05 BR BRPI0709478-7A patent/BRPI0709478A2/en not_active Application Discontinuation
- 2007-04-05 CN CN200780016077.6A patent/CN101437758B/en active Active
- 2007-04-05 RU RU2008143330/05A patent/RU2445264C2/en not_active IP Right Cessation
- 2007-04-05 AU AU2007236547A patent/AU2007236547B2/en active Active
Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4016238A (en) * | 1975-08-29 | 1977-04-05 | Urbina Davalos Fernando | Process for the obtention of alumina and phosphate values by the alkaline decomposition of silica-containing aluminum phosphate ores |
JPS59156489A (en) * | 1983-02-28 | 1984-09-05 | Kurita Water Ind Ltd | Phosphate-contg. water disposal |
US4758412A (en) * | 1985-11-08 | 1988-07-19 | Rhone-Poulenc Specialites Chimiques | Production of rare earth hydroxides from phosphate ores |
US5534235A (en) * | 1995-09-05 | 1996-07-09 | Nalco Chemical Company | Polymers containing phosphonic acid groups for the treatment of red mud in the Bayer process |
WO2006081626A1 (en) * | 2005-02-03 | 2006-08-10 | Alcoa Of Australia Limited | Method for the causticisation of bayer process solutions |
Non-Patent Citations (1)
Title |
---|
PATENT ABSTRACTS OF JAPAN * |
Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN101264910B (en) * | 2008-04-25 | 2010-10-13 | 河南未来铝业(集团)有限公司 | Mother liquor evaporation seed addition method for aluminum hydroxide or aluminum oxide production technique by Bayer process |
FR2934852A1 (en) * | 2008-08-06 | 2010-02-12 | Alcan Int Ltd | IMPROVEMENT TO THE BAYER PROCESS FOR PRODUCTION OF ALUMINA TRIHYDRATE, SAID PROCESS COMPRISING A STEP IN WHICH THE SURSATURATED LIQUEUR IS FILTERED AT HIGH TEMPERATURE BEFORE DECOMPOSITION |
WO2010015738A3 (en) * | 2008-08-06 | 2010-04-01 | Alcan International Limited | Improvement to the bayer process for producing alumina trihydrate, said process comprising a step in which the supersaturated liquor is filtered at high temperature before decomposition |
CN102119124A (en) * | 2008-08-06 | 2011-07-06 | 力拓艾尔坎国际有限公司 | Improvement to the bayer process for producing alumina trihydrate, said process comprising a step in which the supersaturated liquor is filtered at high temperature before decomposition |
US8628738B2 (en) | 2008-08-06 | 2014-01-14 | Rio Tinto Alcan International Limited | Bayer process for producing alumina trihydrate, said process comprising a step in which the supersaturated liquor is filtered at high temperature before decomposition |
AU2009278998B2 (en) * | 2008-08-06 | 2014-02-13 | Rio Tinto Alcan International Limited | Improvement to the bayer process for producing alumina trihydrate, said process comprising a step in which the supersaturated liquor is filtered at high temperature before decomposition |
Also Published As
Publication number | Publication date |
---|---|
AU2007236547B2 (en) | 2012-05-03 |
CN101437758B (en) | 2013-04-24 |
RU2008143330A (en) | 2010-05-20 |
BRPI0709478A2 (en) | 2011-07-19 |
CN101437758A (en) | 2009-05-20 |
AU2007236547A1 (en) | 2007-10-18 |
RU2445264C2 (en) | 2012-03-20 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
AU2005254281B2 (en) | Improvement to the Bayer process for the production of alumina trihydrate by means of alkaline leaching of bauxite, said method comprising a predesilicification step | |
AU648215B2 (en) | Process for the removal of sodium oxalate from solutions of sodium aluminate from the Bayer cycle | |
AU2007236547B2 (en) | Method of reducing calcia concentrations of green Bayer process liquors | |
US5628972A (en) | Process for removing iron in sodium aluminate liquors obtained from alkaline attack of bauxite containing alumina monohydrate | |
US2893840A (en) | Production of magnesium compound | |
US5279806A (en) | Process for eliminating heavy metals from phosphoric acid | |
US5888461A (en) | Process for purifying sodium aluminate solutions containing sodium oxalate | |
RU2491362C1 (en) | Method of extracting rare-earth metals from phosphogypsum | |
US4100264A (en) | Process for the preparation of calcium carbonate for use in fluorescent lamp phosphors | |
JP4566463B2 (en) | Treatment method of electroless nickel plating aging solution | |
EP1301260B1 (en) | Improved process for filter aid production in alumina refineries | |
US3728432A (en) | Purification of sodium aluminate solutions | |
AU650747B2 (en) | Method for controlling sodium oxalate levels in sodium aluminate solutions | |
RU2281248C1 (en) | Process for producing magnesium oxide of highly mineralized brines | |
EP1858808A1 (en) | Method for the causticisation of bayer process solutions | |
JP2006027913A (en) | High purity metal hydroxide, its refining method and production method, hydroxide and oxide obtained by their methods, and synthetic resin composition and synthetic resin molded article | |
SU1490086A1 (en) | Method of processing spent etching solutions | |
RU2071447C1 (en) | Method for production of extraction phosphoric acid | |
AU2001272227B2 (en) | Improved process for filter aid production in alumina refineries | |
KR20190101398A (en) | Release of impurities from calcium-based minerals | |
SU764607A3 (en) | Method of extracting rare-earth elements from apatite | |
Kuznetsova et al. | Effect of magnesium salts on the production of tcha and the feasibility of using the resulting compounds in the leaching of bauxites | |
AU2011250646B2 (en) | Sequestration of carbon dioxide using tricalcium aluminate | |
CA2182744C (en) | Method for the removal of iron from sodium aluminate liquors resulting from alkaline attack on alumina-monohydrate-containing bauxite | |
JPS601069B2 (en) | Method for removing phosphates from wastewater |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
121 | Ep: the epo has been informed by wipo that ep was designated in this application |
Ref document number: 07718707 Country of ref document: EP Kind code of ref document: A1 |
|
DPE1 | Request for preliminary examination filed after expiration of 19th month from priority date (pct application filed from 20040101) | ||
WWE | Wipo information: entry into national phase |
Ref document number: 2007236547 Country of ref document: AU |
|
NENP | Non-entry into the national phase |
Ref country code: DE |
|
WWE | Wipo information: entry into national phase |
Ref document number: 8720/DELNP/2008 Country of ref document: IN |
|
WWE | Wipo information: entry into national phase |
Ref document number: 200780016077.6 Country of ref document: CN |
|
WWE | Wipo information: entry into national phase |
Ref document number: 2008143330 Country of ref document: RU |
|
ENP | Entry into the national phase |
Ref document number: 2007236547 Country of ref document: AU Date of ref document: 20070405 Kind code of ref document: A |
|
122 | Ep: pct application non-entry in european phase |
Ref document number: 07718707 Country of ref document: EP Kind code of ref document: A1 |
|
ENP | Entry into the national phase |
Ref document number: PI0709478 Country of ref document: BR Kind code of ref document: A2 Effective date: 20081007 |