CA1158202A - Upgrading of bauxites, bauxitic clays and aluminum mineral bearing clays by beneficiation - Google Patents
Upgrading of bauxites, bauxitic clays and aluminum mineral bearing clays by beneficiationInfo
- Publication number
- CA1158202A CA1158202A CA000358577A CA358577A CA1158202A CA 1158202 A CA1158202 A CA 1158202A CA 000358577 A CA000358577 A CA 000358577A CA 358577 A CA358577 A CA 358577A CA 1158202 A CA1158202 A CA 1158202A
- Authority
- CA
- Canada
- Prior art keywords
- stage
- product
- minus
- high intensity
- intensity magnetic
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Landscapes
- Manufacture And Refinement Of Metals (AREA)
Abstract
UPGRADING OF BAUXITES, BAUXITIC CLAYS, AND ALUMINUM MINERAL BEARING CLAYS
BY BENEFICIATION
ABSTRACT OF THE DISCLOSURE
A process for the upgrading of aluminum mineral bearing raw materials by using at least three beneficiation treatment stages consisting of dispersion of a pulp of the material in specific pH ranges, screening in specific mesh sizes, and using at least one stage of high intensity magnetic separation.
BY BENEFICIATION
ABSTRACT OF THE DISCLOSURE
A process for the upgrading of aluminum mineral bearing raw materials by using at least three beneficiation treatment stages consisting of dispersion of a pulp of the material in specific pH ranges, screening in specific mesh sizes, and using at least one stage of high intensity magnetic separation.
Description
` 1 1582~
This invention is related to my earlier U.S.
Patent 4,193,791 which in turn is related to my U.S.
Patent No. 4,113,466, granted September 12, 1978, and my pending U.S. Application Serial No. 6,111, filed January 24, 1979.
This invention is primarlly applicable to the up-grading of bauxites, bauxitic clays, and aluminum mineral bearing clays. The conventional method used for the up-grading of bauxites; reference American Institute of Mining and Metallurgical Enyineers, technical paper by Alcan International personnel presented at the 1977 Annual Meeting Atlanta, Georgia, March 6-10, 1977; is to first crush the raw materlal to a specific size, normally three inches, followed by wet screeni`ng at 20 mesh Tyler, retaining the plus 20 mesh size fraction as the upgraded bauxite, and the minus 20 mesh portion is rejected as waste~ The upgradi`ng in this case is mainly to reduce the silica :Ln the plu5 20 mesh product together with some removal of the iron and titanium minerals.
The amount rejected as waste is usually a minimum of 40 per-cent of the original feed mater:ial and contains a relativelyhigh percentage of the desirable aluminum bearing minerals which have the chemical analysis of A12O3.xH2O. In the treatment of clays, in which one of the main uses is for the refractory industry, to the knowledge of the inventor, the only major upgrading that is done on a commercial basis is the use of high magnetic intensity separators using steel wool as the magnetic media primarily for the reduction of the iron content of the raw material. Such magnetic separators are of the type m&n~lfactured by the Sala Company oE Sala, Sweden. In usinq steel wool as a 1 ~ 2 ~ 2 magnetic media, the product must be reduced in size to essentially minus 10 microns, which is difficult and expensive; otherwise any granular material essentially coarser than 10 microns hangs up in the steel wool and entails large losses of the desirable portion of the raw material. In addition, only small amounts of magnetically susceptible material can be economically removed due to the limited amount of magnetics that can be held by the steel wool or alternately, only small tonnages of material can be treated by such a high-intensity magnetic unit entailing high capital costs per ton of materiai treated.
In applying my invention to the upgrading of bauxites, and by the use of a number of low cost beneiciation stages, I
have been able to use a high intensity magnetic separator of the Jones type which entails the use of no specific type of magnetic media such as steel wool, allowing me to remove large quantities of magnetically susceptible minerals and in particular ixon and titanium minerals from the original feed material at a comparatively low cost. Further, if necessary, I use a desliming stage at preferably 2.0 to 10.0 microns, the combination of which upgrades the original bauxite to an appreciably higher grade than was - heretofore possible by the elimination of large amounts of the iron and titanium minerals together with sil.ica, resulting in an appreciably higher grade bauxite than was heretofore economicall~
possible together with an appreciabl.e increase in recovery of ~5 the.desirable A12O3.xH2O minerals, where x is the amount of water chemically combined with the A12O3.
In the treatment to upgrade clays, I use a number o.
novel low cost beneficiation steps including the Jones type magnetic separator, to remove a major portion of the iron and titanium minerals with but minor losses of the desirable aluminum
This invention is related to my earlier U.S.
Patent 4,193,791 which in turn is related to my U.S.
Patent No. 4,113,466, granted September 12, 1978, and my pending U.S. Application Serial No. 6,111, filed January 24, 1979.
This invention is primarlly applicable to the up-grading of bauxites, bauxitic clays, and aluminum mineral bearing clays. The conventional method used for the up-grading of bauxites; reference American Institute of Mining and Metallurgical Enyineers, technical paper by Alcan International personnel presented at the 1977 Annual Meeting Atlanta, Georgia, March 6-10, 1977; is to first crush the raw materlal to a specific size, normally three inches, followed by wet screeni`ng at 20 mesh Tyler, retaining the plus 20 mesh size fraction as the upgraded bauxite, and the minus 20 mesh portion is rejected as waste~ The upgradi`ng in this case is mainly to reduce the silica :Ln the plu5 20 mesh product together with some removal of the iron and titanium minerals.
The amount rejected as waste is usually a minimum of 40 per-cent of the original feed mater:ial and contains a relativelyhigh percentage of the desirable aluminum bearing minerals which have the chemical analysis of A12O3.xH2O. In the treatment of clays, in which one of the main uses is for the refractory industry, to the knowledge of the inventor, the only major upgrading that is done on a commercial basis is the use of high magnetic intensity separators using steel wool as the magnetic media primarily for the reduction of the iron content of the raw material. Such magnetic separators are of the type m&n~lfactured by the Sala Company oE Sala, Sweden. In usinq steel wool as a 1 ~ 2 ~ 2 magnetic media, the product must be reduced in size to essentially minus 10 microns, which is difficult and expensive; otherwise any granular material essentially coarser than 10 microns hangs up in the steel wool and entails large losses of the desirable portion of the raw material. In addition, only small amounts of magnetically susceptible material can be economically removed due to the limited amount of magnetics that can be held by the steel wool or alternately, only small tonnages of material can be treated by such a high-intensity magnetic unit entailing high capital costs per ton of materiai treated.
In applying my invention to the upgrading of bauxites, and by the use of a number of low cost beneiciation stages, I
have been able to use a high intensity magnetic separator of the Jones type which entails the use of no specific type of magnetic media such as steel wool, allowing me to remove large quantities of magnetically susceptible minerals and in particular ixon and titanium minerals from the original feed material at a comparatively low cost. Further, if necessary, I use a desliming stage at preferably 2.0 to 10.0 microns, the combination of which upgrades the original bauxite to an appreciably higher grade than was - heretofore possible by the elimination of large amounts of the iron and titanium minerals together with sil.ica, resulting in an appreciably higher grade bauxite than was heretofore economicall~
possible together with an appreciabl.e increase in recovery of ~5 the.desirable A12O3.xH2O minerals, where x is the amount of water chemically combined with the A12O3.
In the treatment to upgrade clays, I use a number o.
novel low cost beneficiation steps including the Jones type magnetic separator, to remove a major portion of the iron and titanium minerals with but minor losses of the desirable aluminum
2~ 2 bearing minerals, which in this case are normally predominantly Kaolinite, of which the chemical analysis is A12O3.2SiO2.2H2O.
SUMMARY OF THE INVENTION
It is accordingly a primary object of the present in~ention to provide a novel process for the upgrading of bauxites by reducing at least the iron and titanium content of the original material and in most cases, also the percenta~e of silica. It is a further object of the present invention to provide a novel and low-cost process for the upgrading of bauxitic clays and clays to produce a product that is appreciably lower in iron and titanium analysis than the original eed material together with comparatively low losses of the desired contained aluminum bearing mlnerals. Other objects and advant:ages of the claimed invention will become apparent as the description thereof proceeds.
In satisfaction o the foregoing objects and advantages there is presented by this invention in its broadest concept a process for the upgrading of bauxites, bauxitie clays, and clays in which at least the iron and titanium minerals are appreciably reduced-, and in the case of the bauxites, ~he silica content is also appreciably reduced, the process comprisingo (a) Preparation of the raw material - in the treatment of raw materials such as bauxite and bauxitic clays, the normal circuit will consist of crushing to a sufficiently small feed size suitable for furth~r reduction in such comminution units as a rod mill or ball mill. Such feed size will normally be minus 3/4 inch. In my preferred circuit, I use a pulp density for at least one wet grinding stage of 40 to 55 percent solids and maintain the pH at the discharge of the said at least one wet grinding stage of at least 8.5, using at least sodium hydxoxide as the . alkaline agent. Where I use NaOH as the alkaline agent alone or in combination with other alkaline agents selected from the group consisting of KOH, NH40H, and Na2C03, my pH range is about 9.5 to about 12.5. Where I use at least NaOH as the alkaline agent in combination with a dispersing agent selected from the group consisting o lignins, silicates, and phosphates, my pEI range in the at least one wet grinding stage is in the pH
range of about 8 5 to 12.5. sy this means I obtain controlled dispersion.of the solid particles in the pulp which results in high efficiencies of grinding by being able to operate at a comparatively high pulp density level, resulting in low power consumption and excellent liberation characteristics of the various contained minerals, a~ain which results in the ability of the subse~uent high intensity magnetic stage to remove a large percentage of the magnetically susceptible iron and titanium minerals with a comparatively low loss of ~he aluminum bearing minerals which are nonmagnetic.
In treating such raw materials as clay, which may contain only small amounts of coarse material or a negligible amount, I prefer to form a pulp of the oriyinal material in the pulp density range of about 10 percent solids to about 55 percent solids using at least sodium hydroxide as the alkaline and dispersing agent and controlling the pulp pEI in the range of about 9.5 to 12.5, or alternately, as noted above, using sodium hydroxide either in combination with other alkaline agents or sodium hydroxide alone in combination with dispersants, or alternately,sodium hydroxide in combination with other alkaline agen-ts and dispersants.
~ 15~20~
(b~ Following the at least one wet grindiny stage, I
prefer to screen the material to within the range of 10 mesh to 65 mesh Tyler. The oversize ~raction from the screening operation may eithex be sent to waste which would normally consist of wood contained in the original material or alternately return part or all of the oversize fraction to the at least one wet comminution stage. The mesh size that I use in this stage will be dependent upon the subsequent processing steps.
If I use a low to medium high magnetic separation step in which the magnetic separators are of the conventional drum type using either permanent or electromagnetics in which the magnetic field strength is in the range of about 0.5 to 10.0 kilogauss, my preferred screen siæe is in the range of about 10 to 35 mesh. Further, I may omit any screening stage prior to such magnetic cobbing.
If the screen undersize is fed direc-tly to my at least one high magnetic intensity separation stage, my preferred screen size is about 20 mesh to 65 mesh Tyler.
If I subsequently use a desliming stap prior to any magnetic separation, I may use one or more screening stages prior to or after desliming.
(c) High intensity magnetic separation stage in this stage I prefer to use a pulp density of about 15 percent to 45 percent - solids maintaining the pH of the pulp with at least an alkaline agent 25 and in the pH range of 8~5 to 12.5.
In applying my invention to bauxites, I prefer to follow this stage with a desliming step.
(d) Desliming - in the simplest application of the invention, I prefer to deslime the material at a particle si~e of about 2 to about 10 microns using conventional equipment ~5~
such as thickener-sizer separators, hydroseparators, or centrifugal separator~, all well known in the art. The minus fraction from such treatment will normally contain a much higher percentage of the silica than in the original material together with appreciably higher amounts of both iron and titanium minerals than was contai.ned in the original material, thus upgrading the plus fraction which will be impoverished in iron, titanium, and silica than was present in the original feed materialO
Prior to such desli.ming, I may remove a coarser fraction from the material prior to such treatment by using one or more stages of cyclones in which the plus fraction may be as coarse as essentially plus 200 mesh while the essent.ially minus 200 mesh fraction is feed to the above described desliming stage.
In the applieation of the invention to clays, I do not norma.ly use the desliming stage as the losses of the desirable aluminum bearing minerals are too high to be economically feasible.
(e) In the case of the bauxites, fo~lowing the desliming stage, I prefer to treat at least the plus fraetion in at least one additional high magnetic intensity step using the Jones type separator and magnetic field strength in the range of about ll.0 to 22.0 kilogauss. Dependent on the eeonomies, I may also use the steel wool type magnetic separator on the minus 2 to about minus lO mesh fraction to remove residual iron and titani~m and eombining this nonmagnetic fraetion with the nonmagnetic fraction from the plus portion of the separation,or alternately, this minus fraction may be fed to sueh a proeess as the Bayer Process for the aluminum mineral recovery or alternately,have commercial value in the aluminum ehemical products industry.
The following will define for clarity various terms used in describing the invention:
Magnetic Cobblng - passing a prepared pulp of the material through a magnetic field to remove from the material a magnetic concentrate containing a large percentage of the iron and titanium minerals which is rejected as waste, and nonmagnetic product that analyzes appreciably lower in iron and titanium than the original feed material, and containing a high percentage of the original aluminum minerals contained in the material.
Desliming - separation of the fine particles of the prepared material from the coarser fraction.
In the practice of my invention this separation is usually carried out at 2.0 to lO.0 microns, with the minus fraction to waste or some other use such as the Bayer Process, and the plus 2.0 to plus 10.0 microns as the retained product for subse~uent processing or commercial use. This desliming step is only carried out where a relatively high percentage of the iron and titanium minerals in the minus 2.0 to minus 10.0 micron sized ranges will not respond to high magnetic intensity cobbing and the loss of aluminum minerals in this product is either economically acceptable, or that little or no loss of the aluminum minerals takes place where such product can be economically fed to a Bay~r Process.
Bauxites and bauxitic clays - there is a thin line in these definitions. Tha difference between bauxites and - bauxitic clays is essentially the percentages of A12O3.x~I2O
minerals contained in the materials. Where practically all of the silica in these materials is present as Kaolinite, the relati~e percentages of silica are taken as the definitive separation point.
For instance, Arkansas bauxites can be defined as containing appro~imately less than 16 percent SiO2, and ~rkansas bauxitic clays, more than 16 percent sio2.
Clays ~ generally refer to materials containing little or no A12O3.xH2O minerals and the major aluminum mineral component is essentially kaolinite, ~12O3.2SiO2.2H2O.
Alumina - A12O3.
Iron and titanium - the standard practice of the aluminum industry is to report Fe and Ti analys~s as Fe2O3 and Tio2. The iron and titanium minerals contained in the aluminum bearing materials vary considerably and are but rarely only in the form of Fe2O3 and Tio2. For instance,the major iron mineral in Arkansas bauxite is siderite, FeC03, and the commonest occurring form of titanium is as iLmenite, FeOTiO2. When I refer to percentages of Fe2O3 and Tio2 herein, I mean the chemical analyses as Fe and Ti converted to Fe2O3 and TiO2,respectively.
Alkaline agent - an agent used to raise or maintain the pH of the pulp within certain optimum pH ranges. The alkaline agent~ that may be used in this process are alkaline dispersing agents selected from the group consisting of sodium hydroxide, potassium hydroxîde, ammonium hydroxide, sodium carbonate, and mixtures thereof as described herein.
Dispersing agents - families of dispersants such as lignins, phosphates, silicates7 or any other family of specific dispersants which may be economically used to disperse the solids contained in the pulp of the raw material~ and which, in combination with at least one alkaline agent, sodium hydroxide, in specific pH ranges, combines to result in the unique and outstanding metallurgical results in removing iron and titanium minerals from the material by high intensity magnetic separation.
g _ 1 15~2~2 In combining one or more dispersing agents with a-t least sodium hydro~ide as the alkaline agent I have found that fo~ optimum results in removing iron and titanium minerals ~rom the feed material by high intensity magnetic separation, I require the pH of a pulp of the material to be raised to at least 8.5 using at least sodium hydroxide as the alkaline agent and preferably at an optLmum pH point in the range of 9.5 to 12.5.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
In the use of high intensity magnetic separation as the first major process step in remo~ing a high percentage of the contained iron and/or iron and titanium from the feed material, the preparation of the feed material prior to the~
magnetic separation circuit is important.
If the original feed material is too coarse a size as feed to a comminution unit such as a rod mill or ball mill, I
firstly crush and if necessary screen the feed material to the appropriate size and feed it to at least one stage of wet grinding.
To this at least one stage of grinding I add at least sodium hydroxide as a combined alkaline and dispersing agent,contxolling the pH of the pulp discharge from the grinding unit preferably within the pH range of 9.5 to abou-t 12.5. If I combine dispersing agent with at least NaOH as the alkaline agent I may reduce the lower end of the p~ range to about 8.5. By this means I obtain high efficiency in my grinding circuit using pulp densities as high as 60 percent solids, with good liberation o~ the magnetically susceptible minerals, and in particular, the iron and titanium minerals.
2 1~ 2 Without the above noted use of alkaline agents either alone or in combination with dispersing agent, it would be impossible to operate at such high densities with many of the aluminum bearing materials.
My preferred range of pulp density in the at least one wet grinding mill is 45 percent to 55 percent solids.
Following the at least one wet grinding mill I prefer to dilute the pulp to 15 percent to 45 percent solids dependent on the pulp density I subsequently use to the first stage of high intensity magnetic separation. Following the dilution of the pulp I prefer to screen the solids using one or more screens in the range of 20 to 65 Tyler mesh. The oversize from the screening circuit may be sent to waste containing mostly wood which occurs with the ~eed material, or alternately part or all of the oversize can be returned to the wet grinding circuit.
The undersize may be fed as is or further diluted to the at least one stage of high intensity magnetic separation.
My preferred range of pulp densities to this stage is in the ranye of about 15 to 45 percent solids. I preEer to use at least two stages of high intensity magnetic separation.
The magnetic concentrate or concentrates may be sent to a thickener or tailings pond where the solutions are recovered and recirculated to the magnetic or grinding circuits,or alternately, the thickener underflow containing the magnetic concentrate or concentrates reground to liberate further aluminum bearing minerals which may be recovered by an additiona] stage or stages of magnetic separation treatment.
Following the magnetic circuit the nonmagnetic fraction of the feed material may be sent to a thickener, followed by a filter or other means of bulk solution removal such as centrifugal - il --Fl ~5~2 separator, and the filter cake or centrifugal cake sent to storage for partial air drying prior to drying and/or dehydration or directly to dehydration. Alternately, the nonmagnetic fraction may be subjected to a desliming operation using conventional equipment such as cyclones, hydroseparators, and thickening-sizer apparatus such as is used in iron ore beneficiation and well known in the art.
I only use a desliming circuit where substantial amounts of iro~ occur in the minus 2.0 to minus 10.0 micron size range and which iron bearing minerals do not effectively respond to my magnetic separation circuit. Further, this desliming circuit involves a loss of some ofthe aluminum bearing minerals, and if such loss is too high it precludes the use of this circuit.
If the losses in aluminum bearing minerals is within acceptable economic limits, or the contained aluminum beariny minerals can be used and treated in other processes such as the Bayer process, then there is economic justification for the use of this desliming circuit in treating specific materials.
There is a third alternative in treating the deslimed fraction of the feed material and that is feeding it to a magnetic cobbing circuit using a minimum field strength of 160 0 kilogauss and pre~erably in the range of about 18.0 to about 22.0 kilogauss.
This high magnetic intensity field combined with a special design of magnetic media such as the Colbourn magnetic separator using steel balls, or the Sala type magnetic separator using steel wool, may remove sufficient of the contained iron and/or iron and titanium minerals to economically justify such a magnetic circuit with the nonmagnetic fraction combined with the nonmagnetics from the plus 2.0 to plus lOoO micron sized fraction.
Following the desliming circuit, I may or may not use a further stage o~ high intensity magnetic separation on the plus 2 to plus 10 micron sized fraction. The use of such an additional stage is dependent upon the amount of residual magnetically susceptible iron and/or iron and titanium minerals that can be removed and the economics of adding such a stage to the overall circuit.
BRIEF DESCRIPTION OF THE DRAWINGS
Reference is now made to the accompanying drawings wherein:
Figure 1 shows the simplest flow sheet of the invention;
Figure 2 shows the simplest flow sheet of the invention in the treatment of bauxite, bauxitic clays and aluminum mineral bearing clays incorporating at least one wet grinding stage in lS the dispersion stage;
Figure 3 shows incorporation of the dispersion and grinding stages and shows an additional preferred stage of desliming; and Figure 4 shows a preferred flow sheet of the invention using the combination of dispersion and wet grinding followed by screening, and after screening, at least one stage of low to medium intensity magnetic separa~ion prior to the use of at least one stage of high intensity magnetic separation.
As may be understood from this disclosure and drawings, in lts broadest embodiment, this invention provides a process for the upgrading of aluminum mineral bearing materials selected from the group consisting of bauxites, bauxitic clays 9 and aluminum mineral bearing clays comprisin~ the steps of:
11 ~82~2 a) subjecting a pulp of the said material to at least one dispersion stage in the presence of at least sodium hydroxide and in the pH range of about 8.5 to 12.5;
(b~ subsequently subjecting the said pulp to at least one screenin~ stage in the range oE 10 mesh Tyler to 65 mesh Tyler to produce a minus 10 to minus 65 mesh product;
(c) subsequently subjecting said minus 10 to minus b5 mesh product to at least one stage af high intensity magnetic separation using a field strength of about 11.0 to 22O0 kilogauss to produce a magnetic concentrate enriched in iron and titanium minerals, and a nonmagnetic product impoverished in iron and titanium minerals.
The following description of the drawings sets forth additional details and embodiments of the invention.
DETAILED DESCRIPTION OF THE DRAWINGS
__ Figure 1 shows the simplest flow sheet of the invention.
The application of this simplest flow sheet is primarily for the removal of iron and titanium minerals from aluminum mineral bearing clays wherein the natural grain size of the constituent minerals is at least finer than 10 mesh. Such material will not require initial pxeparation, such as crushing. The raw material ~; would normally be fed to a me~hanical agitator using a ship type propeller (not shown) in which mill solution or water would be added to form a pulp at numeral 10, within the pulp density range of 10 to 60~ solids wherein at least sodium hydroxida would be added and the p~ controlled within the range of about 9.5 to 12.5 to obtain dispersion of the contained solids. In one of the preferred embodiments of my invention I prefer to use at least sodium hydroxide as the alkaline agent in combination with 1 ~82~
a dispersant selected from the group consis-ting of lignins, silicates and phosphates and in which the pH is controlled within the range of about 8.5 to 12.5.
Following ~ormation o~ the pulp at this stage, a-t numeral 11, I screen the material in the range of 10 mesh to 65 mesh Tyler. This screening stage is important in the use of my subsequent stage of high intensity magnetic separation wherein the magnetic gap ~not shown), specifically the Jones type magnetic separator, the strength of the magnetic field and the ef~iciency of the removal of the iron and titanium minerals is dependent upon the width Gf the magnetic gap used. Thus, my screen siæe is a function of the high intensity magnetic separator and its efficiency. I have found that the screen s.ize must be so chosen that the maximum sized particle passing through the screen should be at least about 10~ less in dimension than the width of the magnetic gap setting. This use of a screen in such a beneficiation circuit is quite contrary to conventional practice where the screen size is normally determined by the liberation characteristics of the valued mineral constituents. This combination of the screen size and the width of the magnetic gap is one of the features of the invention, particularly in combination with the dispersion stage ahead o* both the screening and the at least one high intensity magnetic separation stage which allows me to operate both the screening stage and the high intensity magnetic separation stage at pulp densities as high as 45~ solids which heretofore, were, to the inventor's knowledge impossible. By being able to operate with such high density~ the residence time of the magnetically susceptible iron and titanium minerals have an appreciably Longer period o~ time in the magnetic field then was heretofore possible. By this means the efficiency o~ my high intensity separation circuit is outstanding.
1 1S~3~2 Numeral 12 shows the oversize from the screening stage either reduced in size by a wet comminution unit, or a portion such as wood, rejected to waste, and the remaining portion ground to minus 10 mesh.
The undersize at 13 may be further diluted to within the range o~ about 10 to 4~ solids~ and fed to the at least one stage of hiyh intensity magnetic separation, shown at 14, using a magnetic field strength of 11.0 to 22.0 kilogauss.
Following this stage the magnetic concentrate, shown at 15, consisting chie~ly of iron and titanium minerals, would normally be fed to a thickener shown at 17, with the thickener overflow at 18 returned as dilution to the magnetic separation ; and comminution of raw material circuits. The underflow, shown at 19, from the thickener is the magnetic concentrate containing chiefly iron and titan:ium minerals and would normally be sent to waste.
The nonmagnetics, shown at 16, produced by the at least one stage of high intensity magnetic separation would normally be sent to thickening and filtering with the solutions shown at numeral 20, from thickening and filtering used as dilution to the magnetic separation and comminution of raw material circuits. The ~ilter cake shown at 21, is the ~inal upgraded aluminum mineral product.
Figure 2 shows the simplest flow sheet of the invention as applied to bauxites, bauxitic clays, and aluminum bearing clays, shown at 22, and as mined or after conventional crushing, and/or ~ashing and screening procedures. Numeral 23 of the flow sheet combines at least one wet grinding stage with dispersion of the solids contained in the pulp. The preferred pulp density of ~L 1582~2 this at least one wet grinding stage is 45 to 55% solids with the minimllm being approximatel~ 25% solids and the maximum about 60% solids and in the presence of at least sodium hydroxide with the p~ maintained in the range of about 9.5 to 12.5.
Numeral 24 shows the screening stage following the at least one wet grinding stage and numerals 25, 26, 27, 2g, 29, 30, 31, 32, 33, and 34 correspond to Figure 1, numerals 12, 13, 14, 15, 17, 18, 19, 16, 20 and 21, respectively, to result in the final productO
Figure 3 incorporates all of Figure 2 to numeral 32 inclusive and without thickening and filtering. From 35, this nonmagnetic product is fed, at numeral 36, to desliming in which preferably the separation is made with conventional equipment, (not shown~ and at 2 to 10 microns, and to as coarse as 200 mesh Tyler. The undersize particles from this separation, shown at numeral 37, are enriched in iron and titanium minerals ; and would normally be sent to waste. The oversize particles,shown at numeral 38, are impoverished in iron and titanium minerals. This product may be treated by either of two alternative procedures. In alternate (1), the oversized particles, shown at 39, are fed to at least one stage of high intensity magnetic separation using a minimum field strength of 11.0 kilogauss with the magnetic concentrate produced, shown at numeral 41, containing chiefly iron and titanium minerals. This product, shown at numeral 42, follows the same flow sheet as Figure 2~
numerals 29, 30 and 31. In alternate (2)l the nonmagnetic fraction shown at numeral 43 is normally subjected to thickening and filtering and as shown at numeral 44, follows the same flow sheet as Figure2, numerals 33, 34.
,202 Figure 4, as shown at numeral 45, is the screen undersize as shown in Figure 2, numerals 22, 23, 24, 25 and 26, diluted to about 15 to 45~ solids as shown at numeral 46, fed to at least one stage and preferably at least two stages of low to medium intensity magnetic separation using magnetic field strengths of 0.5 to 10.0 kilogauss. The magnetic concentrate produced, as shown at numeral 47, will be chiefly iron and titanium minerals and as shown`at numeral 48, will follow the flow sheet as Figure 2, numerals 29, 30, 31.
The nonmagnetic fraction produced, as shown at 49, will follow the flow sheet as Figure 2, numerals 27, 28, 29, 30, 31, 32, 33 and 34.
The following examples are presented to illustrate the invention, but they are not to be considered as limited thereto. In these examples and throughout the specification, parts are by clry weight unless otherwise indicated.
, 1 15~20~
EXAMPLES OF THE OPER~TION OF THE IN~ENTION
In all of the following examples the ore as received was air dried for ease of handling and put through a hammer mill to produce a product that was approximately minus three ~uarter inch.
For pilot plant operation this was the feed material to the single stage ball mill grinding circuit that was used.
For laboratory xesearch work the minus 3/4 inch product was further reduced to minus 6 mesh for grinding in a sing:Le stage laboratory rod or ball mill.
This example is an illustration of employing a preferred embodiment of my invention in using at least one stage of high intensity magnetic separation.
The feed material was an Arkansas bauxite.
The major components of the pilot plant ~ere a ball mill, `~ followed by a 35 mesh screen, a low intensity drum type magnetic separator, a Jones high intensity magnetic separator with reputed magnetic field strength of 14 to 16 kilogauss, and means for thickening, filtering and materials handling.
The feed rate to the ball mill circuit was 800 pounds per hour on a dry ore basis.
NaOH was used alone as the alkaline agent and throughout all of the tests the pH was maintained at the ball mill discharge between 10.7 to 10.9.
The dispersing agent was added to the feed end of the ball mill.
1 15~202 2080 is a lignin compound supplied by the Rayonier Company, a subsidiary of ITT.
HMP is sodium hexametaphosphate.
Orzan is a krade mark of Crown Zellerbach, and is a lignin compound~
Quebracho is a lignin,- and a bark extract from South America.
Unless otherwise stated the solution strengths of all reagents used was 2-1/2~, with the exception of NaOH which was a 10% solution.
In all cases the percent solids in the ball mill discharge was controlled at approximately 50% solids, and the solids to the number one high magnetic intensity stage o~ the Jones Magnetic Separator was 42 to 44%.
The screen oversize was sent to waste as it contained mainly wood.
The drum type magnetic cobber was of low kilogauss strength and not measured. It removed less than 0.2% of the original feed as magnetic particles.
The Jones Magnetic Separator, supplied by Klockner Humboldt Deutz of Cologne7 Germany, had an upper and lower magnetic ring In the following tests 2 magnetic cobbing staqes were made on the top ring and one magnetic cobbing stage on the lower ring, for a total of three magnetic separation stages.
The Eollowing results were obtained with the major variable being the Dispensing Agent.
2~ -1 ~58202 Dispersing ~ - Chemical Analysis and % Wt~
Agent Magnetic Concts. _ Non Magnetics lbs./TonSiO2 Fe2O3 Tio2 % Wt. SiO2 Fe2O3 TiO2 ~ Wt.
SUMMARY OF THE INVENTION
It is accordingly a primary object of the present in~ention to provide a novel process for the upgrading of bauxites by reducing at least the iron and titanium content of the original material and in most cases, also the percenta~e of silica. It is a further object of the present invention to provide a novel and low-cost process for the upgrading of bauxitic clays and clays to produce a product that is appreciably lower in iron and titanium analysis than the original eed material together with comparatively low losses of the desired contained aluminum bearing mlnerals. Other objects and advant:ages of the claimed invention will become apparent as the description thereof proceeds.
In satisfaction o the foregoing objects and advantages there is presented by this invention in its broadest concept a process for the upgrading of bauxites, bauxitie clays, and clays in which at least the iron and titanium minerals are appreciably reduced-, and in the case of the bauxites, ~he silica content is also appreciably reduced, the process comprisingo (a) Preparation of the raw material - in the treatment of raw materials such as bauxite and bauxitic clays, the normal circuit will consist of crushing to a sufficiently small feed size suitable for furth~r reduction in such comminution units as a rod mill or ball mill. Such feed size will normally be minus 3/4 inch. In my preferred circuit, I use a pulp density for at least one wet grinding stage of 40 to 55 percent solids and maintain the pH at the discharge of the said at least one wet grinding stage of at least 8.5, using at least sodium hydxoxide as the . alkaline agent. Where I use NaOH as the alkaline agent alone or in combination with other alkaline agents selected from the group consisting of KOH, NH40H, and Na2C03, my pH range is about 9.5 to about 12.5. Where I use at least NaOH as the alkaline agent in combination with a dispersing agent selected from the group consisting o lignins, silicates, and phosphates, my pEI range in the at least one wet grinding stage is in the pH
range of about 8 5 to 12.5. sy this means I obtain controlled dispersion.of the solid particles in the pulp which results in high efficiencies of grinding by being able to operate at a comparatively high pulp density level, resulting in low power consumption and excellent liberation characteristics of the various contained minerals, a~ain which results in the ability of the subse~uent high intensity magnetic stage to remove a large percentage of the magnetically susceptible iron and titanium minerals with a comparatively low loss of ~he aluminum bearing minerals which are nonmagnetic.
In treating such raw materials as clay, which may contain only small amounts of coarse material or a negligible amount, I prefer to form a pulp of the oriyinal material in the pulp density range of about 10 percent solids to about 55 percent solids using at least sodium hydroxide as the alkaline and dispersing agent and controlling the pulp pEI in the range of about 9.5 to 12.5, or alternately, as noted above, using sodium hydroxide either in combination with other alkaline agents or sodium hydroxide alone in combination with dispersants, or alternately,sodium hydroxide in combination with other alkaline agen-ts and dispersants.
~ 15~20~
(b~ Following the at least one wet grindiny stage, I
prefer to screen the material to within the range of 10 mesh to 65 mesh Tyler. The oversize ~raction from the screening operation may eithex be sent to waste which would normally consist of wood contained in the original material or alternately return part or all of the oversize fraction to the at least one wet comminution stage. The mesh size that I use in this stage will be dependent upon the subsequent processing steps.
If I use a low to medium high magnetic separation step in which the magnetic separators are of the conventional drum type using either permanent or electromagnetics in which the magnetic field strength is in the range of about 0.5 to 10.0 kilogauss, my preferred screen siæe is in the range of about 10 to 35 mesh. Further, I may omit any screening stage prior to such magnetic cobbing.
If the screen undersize is fed direc-tly to my at least one high magnetic intensity separation stage, my preferred screen size is about 20 mesh to 65 mesh Tyler.
If I subsequently use a desliming stap prior to any magnetic separation, I may use one or more screening stages prior to or after desliming.
(c) High intensity magnetic separation stage in this stage I prefer to use a pulp density of about 15 percent to 45 percent - solids maintaining the pH of the pulp with at least an alkaline agent 25 and in the pH range of 8~5 to 12.5.
In applying my invention to bauxites, I prefer to follow this stage with a desliming step.
(d) Desliming - in the simplest application of the invention, I prefer to deslime the material at a particle si~e of about 2 to about 10 microns using conventional equipment ~5~
such as thickener-sizer separators, hydroseparators, or centrifugal separator~, all well known in the art. The minus fraction from such treatment will normally contain a much higher percentage of the silica than in the original material together with appreciably higher amounts of both iron and titanium minerals than was contai.ned in the original material, thus upgrading the plus fraction which will be impoverished in iron, titanium, and silica than was present in the original feed materialO
Prior to such desli.ming, I may remove a coarser fraction from the material prior to such treatment by using one or more stages of cyclones in which the plus fraction may be as coarse as essentially plus 200 mesh while the essent.ially minus 200 mesh fraction is feed to the above described desliming stage.
In the applieation of the invention to clays, I do not norma.ly use the desliming stage as the losses of the desirable aluminum bearing minerals are too high to be economically feasible.
(e) In the case of the bauxites, fo~lowing the desliming stage, I prefer to treat at least the plus fraetion in at least one additional high magnetic intensity step using the Jones type separator and magnetic field strength in the range of about ll.0 to 22.0 kilogauss. Dependent on the eeonomies, I may also use the steel wool type magnetic separator on the minus 2 to about minus lO mesh fraction to remove residual iron and titani~m and eombining this nonmagnetic fraetion with the nonmagnetic fraction from the plus portion of the separation,or alternately, this minus fraction may be fed to sueh a proeess as the Bayer Process for the aluminum mineral recovery or alternately,have commercial value in the aluminum ehemical products industry.
The following will define for clarity various terms used in describing the invention:
Magnetic Cobblng - passing a prepared pulp of the material through a magnetic field to remove from the material a magnetic concentrate containing a large percentage of the iron and titanium minerals which is rejected as waste, and nonmagnetic product that analyzes appreciably lower in iron and titanium than the original feed material, and containing a high percentage of the original aluminum minerals contained in the material.
Desliming - separation of the fine particles of the prepared material from the coarser fraction.
In the practice of my invention this separation is usually carried out at 2.0 to lO.0 microns, with the minus fraction to waste or some other use such as the Bayer Process, and the plus 2.0 to plus 10.0 microns as the retained product for subse~uent processing or commercial use. This desliming step is only carried out where a relatively high percentage of the iron and titanium minerals in the minus 2.0 to minus 10.0 micron sized ranges will not respond to high magnetic intensity cobbing and the loss of aluminum minerals in this product is either economically acceptable, or that little or no loss of the aluminum minerals takes place where such product can be economically fed to a Bay~r Process.
Bauxites and bauxitic clays - there is a thin line in these definitions. Tha difference between bauxites and - bauxitic clays is essentially the percentages of A12O3.x~I2O
minerals contained in the materials. Where practically all of the silica in these materials is present as Kaolinite, the relati~e percentages of silica are taken as the definitive separation point.
For instance, Arkansas bauxites can be defined as containing appro~imately less than 16 percent SiO2, and ~rkansas bauxitic clays, more than 16 percent sio2.
Clays ~ generally refer to materials containing little or no A12O3.xH2O minerals and the major aluminum mineral component is essentially kaolinite, ~12O3.2SiO2.2H2O.
Alumina - A12O3.
Iron and titanium - the standard practice of the aluminum industry is to report Fe and Ti analys~s as Fe2O3 and Tio2. The iron and titanium minerals contained in the aluminum bearing materials vary considerably and are but rarely only in the form of Fe2O3 and Tio2. For instance,the major iron mineral in Arkansas bauxite is siderite, FeC03, and the commonest occurring form of titanium is as iLmenite, FeOTiO2. When I refer to percentages of Fe2O3 and Tio2 herein, I mean the chemical analyses as Fe and Ti converted to Fe2O3 and TiO2,respectively.
Alkaline agent - an agent used to raise or maintain the pH of the pulp within certain optimum pH ranges. The alkaline agent~ that may be used in this process are alkaline dispersing agents selected from the group consisting of sodium hydroxide, potassium hydroxîde, ammonium hydroxide, sodium carbonate, and mixtures thereof as described herein.
Dispersing agents - families of dispersants such as lignins, phosphates, silicates7 or any other family of specific dispersants which may be economically used to disperse the solids contained in the pulp of the raw material~ and which, in combination with at least one alkaline agent, sodium hydroxide, in specific pH ranges, combines to result in the unique and outstanding metallurgical results in removing iron and titanium minerals from the material by high intensity magnetic separation.
g _ 1 15~2~2 In combining one or more dispersing agents with a-t least sodium hydro~ide as the alkaline agent I have found that fo~ optimum results in removing iron and titanium minerals ~rom the feed material by high intensity magnetic separation, I require the pH of a pulp of the material to be raised to at least 8.5 using at least sodium hydroxide as the alkaline agent and preferably at an optLmum pH point in the range of 9.5 to 12.5.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
In the use of high intensity magnetic separation as the first major process step in remo~ing a high percentage of the contained iron and/or iron and titanium from the feed material, the preparation of the feed material prior to the~
magnetic separation circuit is important.
If the original feed material is too coarse a size as feed to a comminution unit such as a rod mill or ball mill, I
firstly crush and if necessary screen the feed material to the appropriate size and feed it to at least one stage of wet grinding.
To this at least one stage of grinding I add at least sodium hydroxide as a combined alkaline and dispersing agent,contxolling the pH of the pulp discharge from the grinding unit preferably within the pH range of 9.5 to abou-t 12.5. If I combine dispersing agent with at least NaOH as the alkaline agent I may reduce the lower end of the p~ range to about 8.5. By this means I obtain high efficiency in my grinding circuit using pulp densities as high as 60 percent solids, with good liberation o~ the magnetically susceptible minerals, and in particular, the iron and titanium minerals.
2 1~ 2 Without the above noted use of alkaline agents either alone or in combination with dispersing agent, it would be impossible to operate at such high densities with many of the aluminum bearing materials.
My preferred range of pulp density in the at least one wet grinding mill is 45 percent to 55 percent solids.
Following the at least one wet grinding mill I prefer to dilute the pulp to 15 percent to 45 percent solids dependent on the pulp density I subsequently use to the first stage of high intensity magnetic separation. Following the dilution of the pulp I prefer to screen the solids using one or more screens in the range of 20 to 65 Tyler mesh. The oversize from the screening circuit may be sent to waste containing mostly wood which occurs with the ~eed material, or alternately part or all of the oversize can be returned to the wet grinding circuit.
The undersize may be fed as is or further diluted to the at least one stage of high intensity magnetic separation.
My preferred range of pulp densities to this stage is in the ranye of about 15 to 45 percent solids. I preEer to use at least two stages of high intensity magnetic separation.
The magnetic concentrate or concentrates may be sent to a thickener or tailings pond where the solutions are recovered and recirculated to the magnetic or grinding circuits,or alternately, the thickener underflow containing the magnetic concentrate or concentrates reground to liberate further aluminum bearing minerals which may be recovered by an additiona] stage or stages of magnetic separation treatment.
Following the magnetic circuit the nonmagnetic fraction of the feed material may be sent to a thickener, followed by a filter or other means of bulk solution removal such as centrifugal - il --Fl ~5~2 separator, and the filter cake or centrifugal cake sent to storage for partial air drying prior to drying and/or dehydration or directly to dehydration. Alternately, the nonmagnetic fraction may be subjected to a desliming operation using conventional equipment such as cyclones, hydroseparators, and thickening-sizer apparatus such as is used in iron ore beneficiation and well known in the art.
I only use a desliming circuit where substantial amounts of iro~ occur in the minus 2.0 to minus 10.0 micron size range and which iron bearing minerals do not effectively respond to my magnetic separation circuit. Further, this desliming circuit involves a loss of some ofthe aluminum bearing minerals, and if such loss is too high it precludes the use of this circuit.
If the losses in aluminum bearing minerals is within acceptable economic limits, or the contained aluminum beariny minerals can be used and treated in other processes such as the Bayer process, then there is economic justification for the use of this desliming circuit in treating specific materials.
There is a third alternative in treating the deslimed fraction of the feed material and that is feeding it to a magnetic cobbing circuit using a minimum field strength of 160 0 kilogauss and pre~erably in the range of about 18.0 to about 22.0 kilogauss.
This high magnetic intensity field combined with a special design of magnetic media such as the Colbourn magnetic separator using steel balls, or the Sala type magnetic separator using steel wool, may remove sufficient of the contained iron and/or iron and titanium minerals to economically justify such a magnetic circuit with the nonmagnetic fraction combined with the nonmagnetics from the plus 2.0 to plus lOoO micron sized fraction.
Following the desliming circuit, I may or may not use a further stage o~ high intensity magnetic separation on the plus 2 to plus 10 micron sized fraction. The use of such an additional stage is dependent upon the amount of residual magnetically susceptible iron and/or iron and titanium minerals that can be removed and the economics of adding such a stage to the overall circuit.
BRIEF DESCRIPTION OF THE DRAWINGS
Reference is now made to the accompanying drawings wherein:
Figure 1 shows the simplest flow sheet of the invention;
Figure 2 shows the simplest flow sheet of the invention in the treatment of bauxite, bauxitic clays and aluminum mineral bearing clays incorporating at least one wet grinding stage in lS the dispersion stage;
Figure 3 shows incorporation of the dispersion and grinding stages and shows an additional preferred stage of desliming; and Figure 4 shows a preferred flow sheet of the invention using the combination of dispersion and wet grinding followed by screening, and after screening, at least one stage of low to medium intensity magnetic separa~ion prior to the use of at least one stage of high intensity magnetic separation.
As may be understood from this disclosure and drawings, in lts broadest embodiment, this invention provides a process for the upgrading of aluminum mineral bearing materials selected from the group consisting of bauxites, bauxitic clays 9 and aluminum mineral bearing clays comprisin~ the steps of:
11 ~82~2 a) subjecting a pulp of the said material to at least one dispersion stage in the presence of at least sodium hydroxide and in the pH range of about 8.5 to 12.5;
(b~ subsequently subjecting the said pulp to at least one screenin~ stage in the range oE 10 mesh Tyler to 65 mesh Tyler to produce a minus 10 to minus 65 mesh product;
(c) subsequently subjecting said minus 10 to minus b5 mesh product to at least one stage af high intensity magnetic separation using a field strength of about 11.0 to 22O0 kilogauss to produce a magnetic concentrate enriched in iron and titanium minerals, and a nonmagnetic product impoverished in iron and titanium minerals.
The following description of the drawings sets forth additional details and embodiments of the invention.
DETAILED DESCRIPTION OF THE DRAWINGS
__ Figure 1 shows the simplest flow sheet of the invention.
The application of this simplest flow sheet is primarily for the removal of iron and titanium minerals from aluminum mineral bearing clays wherein the natural grain size of the constituent minerals is at least finer than 10 mesh. Such material will not require initial pxeparation, such as crushing. The raw material ~; would normally be fed to a me~hanical agitator using a ship type propeller (not shown) in which mill solution or water would be added to form a pulp at numeral 10, within the pulp density range of 10 to 60~ solids wherein at least sodium hydroxida would be added and the p~ controlled within the range of about 9.5 to 12.5 to obtain dispersion of the contained solids. In one of the preferred embodiments of my invention I prefer to use at least sodium hydroxide as the alkaline agent in combination with 1 ~82~
a dispersant selected from the group consis-ting of lignins, silicates and phosphates and in which the pH is controlled within the range of about 8.5 to 12.5.
Following ~ormation o~ the pulp at this stage, a-t numeral 11, I screen the material in the range of 10 mesh to 65 mesh Tyler. This screening stage is important in the use of my subsequent stage of high intensity magnetic separation wherein the magnetic gap ~not shown), specifically the Jones type magnetic separator, the strength of the magnetic field and the ef~iciency of the removal of the iron and titanium minerals is dependent upon the width Gf the magnetic gap used. Thus, my screen siæe is a function of the high intensity magnetic separator and its efficiency. I have found that the screen s.ize must be so chosen that the maximum sized particle passing through the screen should be at least about 10~ less in dimension than the width of the magnetic gap setting. This use of a screen in such a beneficiation circuit is quite contrary to conventional practice where the screen size is normally determined by the liberation characteristics of the valued mineral constituents. This combination of the screen size and the width of the magnetic gap is one of the features of the invention, particularly in combination with the dispersion stage ahead o* both the screening and the at least one high intensity magnetic separation stage which allows me to operate both the screening stage and the high intensity magnetic separation stage at pulp densities as high as 45~ solids which heretofore, were, to the inventor's knowledge impossible. By being able to operate with such high density~ the residence time of the magnetically susceptible iron and titanium minerals have an appreciably Longer period o~ time in the magnetic field then was heretofore possible. By this means the efficiency o~ my high intensity separation circuit is outstanding.
1 1S~3~2 Numeral 12 shows the oversize from the screening stage either reduced in size by a wet comminution unit, or a portion such as wood, rejected to waste, and the remaining portion ground to minus 10 mesh.
The undersize at 13 may be further diluted to within the range o~ about 10 to 4~ solids~ and fed to the at least one stage of hiyh intensity magnetic separation, shown at 14, using a magnetic field strength of 11.0 to 22.0 kilogauss.
Following this stage the magnetic concentrate, shown at 15, consisting chie~ly of iron and titanium minerals, would normally be fed to a thickener shown at 17, with the thickener overflow at 18 returned as dilution to the magnetic separation ; and comminution of raw material circuits. The underflow, shown at 19, from the thickener is the magnetic concentrate containing chiefly iron and titan:ium minerals and would normally be sent to waste.
The nonmagnetics, shown at 16, produced by the at least one stage of high intensity magnetic separation would normally be sent to thickening and filtering with the solutions shown at numeral 20, from thickening and filtering used as dilution to the magnetic separation and comminution of raw material circuits. The ~ilter cake shown at 21, is the ~inal upgraded aluminum mineral product.
Figure 2 shows the simplest flow sheet of the invention as applied to bauxites, bauxitic clays, and aluminum bearing clays, shown at 22, and as mined or after conventional crushing, and/or ~ashing and screening procedures. Numeral 23 of the flow sheet combines at least one wet grinding stage with dispersion of the solids contained in the pulp. The preferred pulp density of ~L 1582~2 this at least one wet grinding stage is 45 to 55% solids with the minimllm being approximatel~ 25% solids and the maximum about 60% solids and in the presence of at least sodium hydroxide with the p~ maintained in the range of about 9.5 to 12.5.
Numeral 24 shows the screening stage following the at least one wet grinding stage and numerals 25, 26, 27, 2g, 29, 30, 31, 32, 33, and 34 correspond to Figure 1, numerals 12, 13, 14, 15, 17, 18, 19, 16, 20 and 21, respectively, to result in the final productO
Figure 3 incorporates all of Figure 2 to numeral 32 inclusive and without thickening and filtering. From 35, this nonmagnetic product is fed, at numeral 36, to desliming in which preferably the separation is made with conventional equipment, (not shown~ and at 2 to 10 microns, and to as coarse as 200 mesh Tyler. The undersize particles from this separation, shown at numeral 37, are enriched in iron and titanium minerals ; and would normally be sent to waste. The oversize particles,shown at numeral 38, are impoverished in iron and titanium minerals. This product may be treated by either of two alternative procedures. In alternate (1), the oversized particles, shown at 39, are fed to at least one stage of high intensity magnetic separation using a minimum field strength of 11.0 kilogauss with the magnetic concentrate produced, shown at numeral 41, containing chiefly iron and titanium minerals. This product, shown at numeral 42, follows the same flow sheet as Figure 2~
numerals 29, 30 and 31. In alternate (2)l the nonmagnetic fraction shown at numeral 43 is normally subjected to thickening and filtering and as shown at numeral 44, follows the same flow sheet as Figure2, numerals 33, 34.
,202 Figure 4, as shown at numeral 45, is the screen undersize as shown in Figure 2, numerals 22, 23, 24, 25 and 26, diluted to about 15 to 45~ solids as shown at numeral 46, fed to at least one stage and preferably at least two stages of low to medium intensity magnetic separation using magnetic field strengths of 0.5 to 10.0 kilogauss. The magnetic concentrate produced, as shown at numeral 47, will be chiefly iron and titanium minerals and as shown`at numeral 48, will follow the flow sheet as Figure 2, numerals 29, 30, 31.
The nonmagnetic fraction produced, as shown at 49, will follow the flow sheet as Figure 2, numerals 27, 28, 29, 30, 31, 32, 33 and 34.
The following examples are presented to illustrate the invention, but they are not to be considered as limited thereto. In these examples and throughout the specification, parts are by clry weight unless otherwise indicated.
, 1 15~20~
EXAMPLES OF THE OPER~TION OF THE IN~ENTION
In all of the following examples the ore as received was air dried for ease of handling and put through a hammer mill to produce a product that was approximately minus three ~uarter inch.
For pilot plant operation this was the feed material to the single stage ball mill grinding circuit that was used.
For laboratory xesearch work the minus 3/4 inch product was further reduced to minus 6 mesh for grinding in a sing:Le stage laboratory rod or ball mill.
This example is an illustration of employing a preferred embodiment of my invention in using at least one stage of high intensity magnetic separation.
The feed material was an Arkansas bauxite.
The major components of the pilot plant ~ere a ball mill, `~ followed by a 35 mesh screen, a low intensity drum type magnetic separator, a Jones high intensity magnetic separator with reputed magnetic field strength of 14 to 16 kilogauss, and means for thickening, filtering and materials handling.
The feed rate to the ball mill circuit was 800 pounds per hour on a dry ore basis.
NaOH was used alone as the alkaline agent and throughout all of the tests the pH was maintained at the ball mill discharge between 10.7 to 10.9.
The dispersing agent was added to the feed end of the ball mill.
1 15~202 2080 is a lignin compound supplied by the Rayonier Company, a subsidiary of ITT.
HMP is sodium hexametaphosphate.
Orzan is a krade mark of Crown Zellerbach, and is a lignin compound~
Quebracho is a lignin,- and a bark extract from South America.
Unless otherwise stated the solution strengths of all reagents used was 2-1/2~, with the exception of NaOH which was a 10% solution.
In all cases the percent solids in the ball mill discharge was controlled at approximately 50% solids, and the solids to the number one high magnetic intensity stage o~ the Jones Magnetic Separator was 42 to 44%.
The screen oversize was sent to waste as it contained mainly wood.
The drum type magnetic cobber was of low kilogauss strength and not measured. It removed less than 0.2% of the original feed as magnetic particles.
The Jones Magnetic Separator, supplied by Klockner Humboldt Deutz of Cologne7 Germany, had an upper and lower magnetic ring In the following tests 2 magnetic cobbing staqes were made on the top ring and one magnetic cobbing stage on the lower ring, for a total of three magnetic separation stages.
The Eollowing results were obtained with the major variable being the Dispensing Agent.
2~ -1 ~58202 Dispersing ~ - Chemical Analysis and % Wt~
Agent Magnetic Concts. _ Non Magnetics lbs./TonSiO2 Fe2O3 Tio2 % Wt. SiO2 Fe2O3 TiO2 ~ Wt.
3.97 lbs/Ton 11.0 23.7 5.2 19.2 17.8 1.69 1.35 81.8 HMP
1.0 lbs/Ton 9.3 31.2 5.4 16.7 18.0 1.85 1.50 83.3 HMP
1.0 lbs/Ton 10.4 26.9 5.5 16.1 17.9 1.67 1.45 83.3 and ~uebracho 0.75 lbs/Ton Quebracho 1.06 lbs/Ton 9.6 27.9 5.4 15.6 18.0 1.81 1.46 84.4 arid Orzan ~
0~61 lbs/Ton Note: Average head analysis was 16.0% SiO2 6.2~ Fe2O3, and 2.0~ Tio2.
; The following pilot plant run was made on an Arkansas Bauxitic Clay using the same circuitry as in Example 1. The major difference was in the ~ solids to the number one magnetic co~bing stage of the Jones Magnetic separator; this was 19.0%
solids.
The Alkaline Agent was NaOH, and the pH in the circuit maintained at 10.7 to 10.8, and the Dispersing Agent was Quebracho used at the rate oE 0.5 lbs/ton of ore.
The following results were obtained:
~ Chemical Analysis and ~ Wt.
Magnetic Concts. Non Ma~netics SiO2 Fe2O3 Tio2 ~ Wt. SiO2 Fe2O3 Tio2 -~O Wt.
21.8 21.9 7.2 11.7 32.9 0.88 1.14 88.3 Note: llead analysis of feed was 31.5~ Si~2, 3.34% Fe2O3 and 1.99~ TiO2.
EX~MPLE 3 This example is an illustration of employing a preferred embodiment of my invention in using at least one stage of high intensity magnetic separation and at least one stage of desliming.
The ore used was a Bauxite from South America which had been conventionally treated by crushing and washing out o~
the fines.
The head analysis was as follows:
Chemical Analysi _- r~6 sio2 Fe23 Tio2 P20.5
1.0 lbs/Ton 9.3 31.2 5.4 16.7 18.0 1.85 1.50 83.3 HMP
1.0 lbs/Ton 10.4 26.9 5.5 16.1 17.9 1.67 1.45 83.3 and ~uebracho 0.75 lbs/Ton Quebracho 1.06 lbs/Ton 9.6 27.9 5.4 15.6 18.0 1.81 1.46 84.4 arid Orzan ~
0~61 lbs/Ton Note: Average head analysis was 16.0% SiO2 6.2~ Fe2O3, and 2.0~ Tio2.
; The following pilot plant run was made on an Arkansas Bauxitic Clay using the same circuitry as in Example 1. The major difference was in the ~ solids to the number one magnetic co~bing stage of the Jones Magnetic separator; this was 19.0%
solids.
The Alkaline Agent was NaOH, and the pH in the circuit maintained at 10.7 to 10.8, and the Dispersing Agent was Quebracho used at the rate oE 0.5 lbs/ton of ore.
The following results were obtained:
~ Chemical Analysis and ~ Wt.
Magnetic Concts. Non Ma~netics SiO2 Fe2O3 Tio2 ~ Wt. SiO2 Fe2O3 Tio2 -~O Wt.
21.8 21.9 7.2 11.7 32.9 0.88 1.14 88.3 Note: llead analysis of feed was 31.5~ Si~2, 3.34% Fe2O3 and 1.99~ TiO2.
EX~MPLE 3 This example is an illustration of employing a preferred embodiment of my invention in using at least one stage of high intensity magnetic separation and at least one stage of desliming.
The ore used was a Bauxite from South America which had been conventionally treated by crushing and washing out o~
the fines.
The head analysis was as follows:
Chemical Analysi _- r~6 sio2 Fe23 Tio2 P20.5
4.0 8.1 1.0 0.12 600 grams of the dried material was ground in a laboratory rod mill at 50% solids with 12 ccs of 106 NaOH and 6 ccs of 2080 for 8.0 minutes. Following the ball mill the pulp was conditioned for 15 minutes in a Wemco~cell with the pH adjusted to 12.0 with NaOH and then subjected to two stages of magnetic cobbing in a laboratory size Colburn high intensity magnetic unit. The two magnetic concentrates were cleaned once with the cleaner tailings returned to the non-magnetic portion of the pulp.
The total non-magnetic portion was subjected to a desliming stage using a thickener-sizer as the equipment.
The following results were obtained:
Product P6 Chemical Analysis - g6 Produced Wt. SiO2 Fe23 Tio2 2 5 Magnetic Concentrate13.7 3.90 29.3 1.52 Deslime Product Minus 5 microns 13.6 9.40 19.7 3.20 Deslime Product Plus 5 microns 72.7 3.15 1.39 0.53 0.003 1 00 . O
:~i Registered Trade ~lark ~ IOf~ i303 for Ore Clqssi~ie,-s.
~ 1S82~2 As in Examples 1 and 2 the excellent metallurgical separation of the iron and titanium minerals with but minor losses in alumina are to be noted. In addition, these are low cost beneficiation steps.
.
This example is an illustration of employing a preferred embodiment of my invention in using at least one stage of high magnetic intensity separation prior to desliminy, a desliming stage, and finally at least one stage o~ high magnetic intensity separation following desliming.
The ore used in this example was a Bauxite from Africa and had the following analysis:
Chemical Analysis - %
sio2 Fe203 Tio2 1.09 6.59 2.95 600 grams of the material was ground for S minutes in a laboratory ball mill at 50% solids and a pH of 10.3 using 8ccs. of 10%
NaOH and 18ccs. of 2-1/2~ Quebracho solution. Following the grinding stage the pulp was transferred to a Wemco cell and conditioned for 5.0 minutes with the pulp pH adjusted to 10.5 with NaOH.
The pulp was then given a single stage high magnetic intensity pass through a Colburn laboratory unit and cleaned once with the cleaner tailings combined with the non-magnetic fraction produced. The total non-magnetics were then deslimed at approximately 5 microns using a laboratory thickener-sizer unit.
The plus 5 micron sized fraction was then diluted to approximately 20% solids and subjected to two passes through the Colburn unit at high magnetic intensity. The two magnetic 1 ~5~202 concentrates were combined and cleaned once with -the cleaner tailings combined with the non magnetic fraction.
The following results were obtained:
Chemical Analysis - %
Product %
Produced Wt~ SiO2 2 3 Tio2 Magnetic Conct. 1 Prior to Desliming8.3 1.5840.8 12.1 Deslime Product Minus 5 micxons19.8 1.428.8 3.5 Masnetic Conct. 2 Af~er Desliming 5.2 0~9611.0 4.6 Deslime Product Plus 5 microns 66.7 0.851.57 1.53 The Deslime Product Minus 5 microns and the Magnetic Conct. 2 after desliming are suitable feed materials to the Bayer Process, while the Deslime Product plus 5 microns is an out-standing product for use in the chemical or refractory industries.
The magnetic Conct. 1, prior to desliming, would be a waste product.
This example is a preferred embodiment of my invention using in the beneficiation circuit three stages of high intensity magnetic cobbing in a Jones magnetic separator to produce three magnetic concentrates that were combined and hereafter referred to as "Total Magnetic Concentrate", and a non magnetic product. The non magnetic product was fed to a high efficiency cyclone to produce two products, the "Cyclone ~nderflow" which was substantially plus 500 Tyler Mesh, and the Cyclone Overflow which in turn was ~ed to a centrifuge for desliming at approximately 5.0 microns. Two products were produced from the centrifuge, and hereafter referred to as "Centrifuge Minus 5 Microns" and "Centrifuge Plus 5 ~icrons".
2 ~ 2 The ore used for this example was a bauxite from South America and was particularly high in iron content.
The ore was treated as mined without the normal screening and washing procedures that eliminates, on a material of this type, about ~0% or more as wasteO
The beneficiation circuit used was a continuous operating pilot plant involving a single ball mill in which the pulp density was 51% solids, the pH at the mill discharge maintained at 10.7 to 10.8 with NaOH, and 0.6 lbs. Quebracho per dry ton of feed, and 1.0 lbs. Orzan~per dry ton feed were added to the ball mill intake.
Following the ball mill; the product was fed to a 28 mesh screen with the oversize, mainly wood, to waste, and the undersize diluted to 28% solids and fed to a Jones High Intensity Magnetic Separator, followed by 2 more passes through th2 separator.
The three magnetic concentrates produced were combined into the "Total Magnetic Concentrate". Th~e nonmaynetic product was fed to a high efficiency cyclone producing a Cyclone Underflow containing about 75% plus 500 mesh and a Cyclone Overflow that was approximately 85~ minus 500 mesh.
The Cyclone overflow was fed to a Bird Centrifuge producing an underflow product essentially plus 5 microns and an overflow product essentially minus 5 microns.
The gap setting on the Jones Magnetic Separator was 0.50 to 0.60 millimeters. The screen size preceding the magnetic separator was 35 mesh. When using such a low gap setting the maximum sizing o my screening stage is 2~ mesh and preferably 35 to ~8 mesh.
~ ~ 5~202 The following results were obtained:
Product Chemical Analysis - %
Produced_ ~ Wt SiO2 Fe2O3 TiO2 Total Magnetic Concentrate 18.2 6.1 48.6 1.76 Centrifuge Minus 5 Microns 15.0 19.2 28.2 5.83 Centrifuge P]us 5 Microns 27.3 3.35 6.7 1.70 Cyclone Underflow 39.5 2.7 2.8 0.92 Calculated Heads 100.0 6.1 16.0 2.0 The "Total Magnetic Concentrate" and the "Centrifuge Minus 5 Microns" would be treated as waste.
The "Centrifuge Plus 5 Microns" is excellent feed to the Bayer Process and appreciably hlgher in recoverable alumina content than conventionally crushed and washed Bauxite that is ~; in planned production from the same geological area.
The "Cyclone Underflow" is an excellent alumina product, and as a fire retardant would be considered a premlum product.
The following table shows the complete analysis of the combined cyclone underflow and centrifuge plus 5 micron products with the Al2O3 conventionally calculated.
~ Wt. Chemical Analysis_- %
Recovery ~123 SiO2 Fe23 Tio2 L.O~I.
66.8 61.3 2.9 4.4 1.2 30.2 - 2~ -~ :L582~2 This is outstanding metallurgy with the high grade alumina concentrate produced and a caustic soluble alumina recovery of appro~imately 90% of the originally contained caustic soluble alumina in the feed sample.
This example illustrates a preferred embodiment of the invention wherein the raw material was ground in a laboratory rod mill using NaOH in combination with a dispersant; screened ;~ at 35 T~ler mesh with the plus 35 mesh being only a trace and discarded and the minus 35 mesh conditioned at a pH of 10.5 , using NaOH as the alkaline agent; the pulp waC then subjectéd to three stages of high intensity magnetic separation to produce three magnetic concentrates and a nonmagnetic product containing in excess of 90% of the original aluminum bearing minerals.
The following were th~ test conditions:
~he feed sample~was a ~auxite from South America and prepared as previously described.
A 600 gram charge was ground in a laboratory rod mill at 50% solids with the addition of 3.0 ccs 10% NaOH solution and 3.0 ccs 2-1/2% Quebracho solution. The pH at the end of grinding was 8.7. The pulp from the rod mill was screened on a 35 Tyler mesh with the plus 35 mesh containing mostly wood and rejected to waste.
The minus 35 mesh was transferred to a Wemco laboratory cell and conditioned for 15 minutes with the pH adjusted to 10.5 with NaOH. The pulp was then subjected to three stages of magnetic separation using a Colburn high intensity magnetic separator.
2 0 ~
The following results were obtained:
Product % Chemical Analysis - %
Produced Wt- SiO2 Fe23 Ti2 MagO Conct. 16.3 1.2 43.1 3.0 Mag. Conct. 22.6 2.7 13.8 2.6 Mag. Conct. 31.6 4.0 8.2 2.2 Nonmagnetic Product 89.5 3.0 1.4 1.3 This example illustrates a preferred embodiment of the invention using the same raw material as in Example 6 and duplicating the same circuit with the exception oE using 4 ccs 10% NaOH solution to the laboratory rod mill, raising the discharge pH to 10.5, and desliming the nonmagnetic product at about 10 microns using a laboratory thickener-sizer as the desliming equipment.
The following re~ults were obtained with the three magnetic concentrates produced combined and referred to as the magnetic concentrate, i.e., "mag. conct.".
Product % Chemical Analysis - %
Produced Wto SiO2 Fe23 TiO2 Mag. Conct. 10.1 1.8 31~3 2.8 Minus 10 Micron Product 34~5 2.9 3.1 1.7 Plus 10 Micron Product 55.4 2.7 0.8 1.2 The Mag. Conct., and the Minus 10 Micron Product are satisfactory feed to the Bayer Process and the Plus 10 Micron Product is outstanding and a premium product for use in the refractories industry.
2~
EXAMPhE 8 This example illustrates a preferred embodiment of my invention with high intensity magnetic cobbing prior to desliming and followed by high intensity magnetic cobbing on the coarse fraction produced from the desliming stage.
The ore sample used was a South American bauxite with ¦ a high iron content.
¦ A 600 gram prepared sample of the material was ground ! i~ a laboratory rod mill at 50% solid~ and with the addition oE
6 ccs 10% NaOH solution and 18 ccs. 2-1/2% Quebracho solution.
he pH at the end of grinding was 10.4. The pulp from the rod mill was screened on 35 Tyler mesh with the plus 35 mesh mainly wood particles and rejected as waste. The minus 35 mesh was transferred to a laboratory sized Wemco flotation cell and conditioned for 15 minutes with the pH adjusted to 10.8 with ¦ NaOH, The pulp was then subjected to three stages of high intensity magnetic separation using the Colbourn magnetic separator with the first magnetic concentrate kept separate, and hereafter referred to as mag. conct. 1, and the next two magnetic concentrates combined and hereafter referred to as mag. conct. 2.
The nonmagnetic product produced was subjected to desliming at approximately 10 microns using a laboratory thickener-sizer apparatus to produce a plus 10 micron sized product and a minus 10 micron sized pxoduct.
The plus 10 micron product was subjected to two stages of high intensity magnetic separation using the Colburn magnetic separator with the two magnetic concentrates produced combined and hereafter referred to as magO conct. 3, and a final nonmagnetic product.
82~
The following results were obtained:
Product % Chemical Analysis - ~
Produced 123SiO2 Fe23 Tio2 L.O.I
Mag~ Conct. 1 8.0 - 2.4 74.8 1.5 Mag. Conct. 2 5.8 - 2.5 44.9 1.9 Minus 10 Microns 25.4 - 15.1 27.4 5.2 Mag. Conct. 3 2.4 - 2.5 12.0 1.8 Nonmagnetics Plus 10 Microns 58.463.1 1.7 1.8 0.8 32.6 :
Calculated Head Sample Ana:Lysis 100.050O7 4.2 16.9 2.1 26.1 10The Mag. Conct. 1, Mag. Conct. 2, and the Minus 10 Micron Products would be treated as waste. Mag. Conct. 3 would be satisfactory feed material to the Bayer Process.
The Nonmagnetics Plus 10 Microns Product is outstanding as a product for use in the chemical industry such as a premium ; 15grade fire retardant with a loss on ignition analysis of 32.6 as against a maximum possible of approximately 34.5%.
In one preferred embodiment of the invention, I
use one or more stages of desliming following my at least one stage of high intensity magnetic separation. However, dependent on the type of material and the circuitry used I may use one or more stages of desliming at any point in the circuit following my dispersion-grinding stage.
Where I use a low to medium intensity magnetic stage or desliming or both ahead of my at least one high intensity magnetic stage I can use the at least one screening stage at any point in the circuit following the dlspersion-grinding stage and prior to the at least one high intensity magnetic stage.
1 ~58202 In my one at least high intensity magnetic stage the magnetic gap width is in the range of about 0.35 millimeters to 2.0 millimeters. The width of the gap is de-termined by measuring the closest distance between opposing ridges of north and south poles and i5 well understood in the art.
The invention has been described herein with reference to certain preferred embodiments. However, as obvious variations thereon will become apparent to those skilled in the art, the invention-is not considered to be limited thereto.
The total non-magnetic portion was subjected to a desliming stage using a thickener-sizer as the equipment.
The following results were obtained:
Product P6 Chemical Analysis - g6 Produced Wt. SiO2 Fe23 Tio2 2 5 Magnetic Concentrate13.7 3.90 29.3 1.52 Deslime Product Minus 5 microns 13.6 9.40 19.7 3.20 Deslime Product Plus 5 microns 72.7 3.15 1.39 0.53 0.003 1 00 . O
:~i Registered Trade ~lark ~ IOf~ i303 for Ore Clqssi~ie,-s.
~ 1S82~2 As in Examples 1 and 2 the excellent metallurgical separation of the iron and titanium minerals with but minor losses in alumina are to be noted. In addition, these are low cost beneficiation steps.
.
This example is an illustration of employing a preferred embodiment of my invention in using at least one stage of high magnetic intensity separation prior to desliminy, a desliming stage, and finally at least one stage o~ high magnetic intensity separation following desliming.
The ore used in this example was a Bauxite from Africa and had the following analysis:
Chemical Analysis - %
sio2 Fe203 Tio2 1.09 6.59 2.95 600 grams of the material was ground for S minutes in a laboratory ball mill at 50% solids and a pH of 10.3 using 8ccs. of 10%
NaOH and 18ccs. of 2-1/2~ Quebracho solution. Following the grinding stage the pulp was transferred to a Wemco cell and conditioned for 5.0 minutes with the pulp pH adjusted to 10.5 with NaOH.
The pulp was then given a single stage high magnetic intensity pass through a Colburn laboratory unit and cleaned once with the cleaner tailings combined with the non-magnetic fraction produced. The total non-magnetics were then deslimed at approximately 5 microns using a laboratory thickener-sizer unit.
The plus 5 micron sized fraction was then diluted to approximately 20% solids and subjected to two passes through the Colburn unit at high magnetic intensity. The two magnetic 1 ~5~202 concentrates were combined and cleaned once with -the cleaner tailings combined with the non magnetic fraction.
The following results were obtained:
Chemical Analysis - %
Product %
Produced Wt~ SiO2 2 3 Tio2 Magnetic Conct. 1 Prior to Desliming8.3 1.5840.8 12.1 Deslime Product Minus 5 micxons19.8 1.428.8 3.5 Masnetic Conct. 2 Af~er Desliming 5.2 0~9611.0 4.6 Deslime Product Plus 5 microns 66.7 0.851.57 1.53 The Deslime Product Minus 5 microns and the Magnetic Conct. 2 after desliming are suitable feed materials to the Bayer Process, while the Deslime Product plus 5 microns is an out-standing product for use in the chemical or refractory industries.
The magnetic Conct. 1, prior to desliming, would be a waste product.
This example is a preferred embodiment of my invention using in the beneficiation circuit three stages of high intensity magnetic cobbing in a Jones magnetic separator to produce three magnetic concentrates that were combined and hereafter referred to as "Total Magnetic Concentrate", and a non magnetic product. The non magnetic product was fed to a high efficiency cyclone to produce two products, the "Cyclone ~nderflow" which was substantially plus 500 Tyler Mesh, and the Cyclone Overflow which in turn was ~ed to a centrifuge for desliming at approximately 5.0 microns. Two products were produced from the centrifuge, and hereafter referred to as "Centrifuge Minus 5 Microns" and "Centrifuge Plus 5 ~icrons".
2 ~ 2 The ore used for this example was a bauxite from South America and was particularly high in iron content.
The ore was treated as mined without the normal screening and washing procedures that eliminates, on a material of this type, about ~0% or more as wasteO
The beneficiation circuit used was a continuous operating pilot plant involving a single ball mill in which the pulp density was 51% solids, the pH at the mill discharge maintained at 10.7 to 10.8 with NaOH, and 0.6 lbs. Quebracho per dry ton of feed, and 1.0 lbs. Orzan~per dry ton feed were added to the ball mill intake.
Following the ball mill; the product was fed to a 28 mesh screen with the oversize, mainly wood, to waste, and the undersize diluted to 28% solids and fed to a Jones High Intensity Magnetic Separator, followed by 2 more passes through th2 separator.
The three magnetic concentrates produced were combined into the "Total Magnetic Concentrate". Th~e nonmaynetic product was fed to a high efficiency cyclone producing a Cyclone Underflow containing about 75% plus 500 mesh and a Cyclone Overflow that was approximately 85~ minus 500 mesh.
The Cyclone overflow was fed to a Bird Centrifuge producing an underflow product essentially plus 5 microns and an overflow product essentially minus 5 microns.
The gap setting on the Jones Magnetic Separator was 0.50 to 0.60 millimeters. The screen size preceding the magnetic separator was 35 mesh. When using such a low gap setting the maximum sizing o my screening stage is 2~ mesh and preferably 35 to ~8 mesh.
~ ~ 5~202 The following results were obtained:
Product Chemical Analysis - %
Produced_ ~ Wt SiO2 Fe2O3 TiO2 Total Magnetic Concentrate 18.2 6.1 48.6 1.76 Centrifuge Minus 5 Microns 15.0 19.2 28.2 5.83 Centrifuge P]us 5 Microns 27.3 3.35 6.7 1.70 Cyclone Underflow 39.5 2.7 2.8 0.92 Calculated Heads 100.0 6.1 16.0 2.0 The "Total Magnetic Concentrate" and the "Centrifuge Minus 5 Microns" would be treated as waste.
The "Centrifuge Plus 5 Microns" is excellent feed to the Bayer Process and appreciably hlgher in recoverable alumina content than conventionally crushed and washed Bauxite that is ~; in planned production from the same geological area.
The "Cyclone Underflow" is an excellent alumina product, and as a fire retardant would be considered a premlum product.
The following table shows the complete analysis of the combined cyclone underflow and centrifuge plus 5 micron products with the Al2O3 conventionally calculated.
~ Wt. Chemical Analysis_- %
Recovery ~123 SiO2 Fe23 Tio2 L.O~I.
66.8 61.3 2.9 4.4 1.2 30.2 - 2~ -~ :L582~2 This is outstanding metallurgy with the high grade alumina concentrate produced and a caustic soluble alumina recovery of appro~imately 90% of the originally contained caustic soluble alumina in the feed sample.
This example illustrates a preferred embodiment of the invention wherein the raw material was ground in a laboratory rod mill using NaOH in combination with a dispersant; screened ;~ at 35 T~ler mesh with the plus 35 mesh being only a trace and discarded and the minus 35 mesh conditioned at a pH of 10.5 , using NaOH as the alkaline agent; the pulp waC then subjectéd to three stages of high intensity magnetic separation to produce three magnetic concentrates and a nonmagnetic product containing in excess of 90% of the original aluminum bearing minerals.
The following were th~ test conditions:
~he feed sample~was a ~auxite from South America and prepared as previously described.
A 600 gram charge was ground in a laboratory rod mill at 50% solids with the addition of 3.0 ccs 10% NaOH solution and 3.0 ccs 2-1/2% Quebracho solution. The pH at the end of grinding was 8.7. The pulp from the rod mill was screened on a 35 Tyler mesh with the plus 35 mesh containing mostly wood and rejected to waste.
The minus 35 mesh was transferred to a Wemco laboratory cell and conditioned for 15 minutes with the pH adjusted to 10.5 with NaOH. The pulp was then subjected to three stages of magnetic separation using a Colburn high intensity magnetic separator.
2 0 ~
The following results were obtained:
Product % Chemical Analysis - %
Produced Wt- SiO2 Fe23 Ti2 MagO Conct. 16.3 1.2 43.1 3.0 Mag. Conct. 22.6 2.7 13.8 2.6 Mag. Conct. 31.6 4.0 8.2 2.2 Nonmagnetic Product 89.5 3.0 1.4 1.3 This example illustrates a preferred embodiment of the invention using the same raw material as in Example 6 and duplicating the same circuit with the exception oE using 4 ccs 10% NaOH solution to the laboratory rod mill, raising the discharge pH to 10.5, and desliming the nonmagnetic product at about 10 microns using a laboratory thickener-sizer as the desliming equipment.
The following re~ults were obtained with the three magnetic concentrates produced combined and referred to as the magnetic concentrate, i.e., "mag. conct.".
Product % Chemical Analysis - %
Produced Wto SiO2 Fe23 TiO2 Mag. Conct. 10.1 1.8 31~3 2.8 Minus 10 Micron Product 34~5 2.9 3.1 1.7 Plus 10 Micron Product 55.4 2.7 0.8 1.2 The Mag. Conct., and the Minus 10 Micron Product are satisfactory feed to the Bayer Process and the Plus 10 Micron Product is outstanding and a premium product for use in the refractories industry.
2~
EXAMPhE 8 This example illustrates a preferred embodiment of my invention with high intensity magnetic cobbing prior to desliming and followed by high intensity magnetic cobbing on the coarse fraction produced from the desliming stage.
The ore sample used was a South American bauxite with ¦ a high iron content.
¦ A 600 gram prepared sample of the material was ground ! i~ a laboratory rod mill at 50% solid~ and with the addition oE
6 ccs 10% NaOH solution and 18 ccs. 2-1/2% Quebracho solution.
he pH at the end of grinding was 10.4. The pulp from the rod mill was screened on 35 Tyler mesh with the plus 35 mesh mainly wood particles and rejected as waste. The minus 35 mesh was transferred to a laboratory sized Wemco flotation cell and conditioned for 15 minutes with the pH adjusted to 10.8 with ¦ NaOH, The pulp was then subjected to three stages of high intensity magnetic separation using the Colbourn magnetic separator with the first magnetic concentrate kept separate, and hereafter referred to as mag. conct. 1, and the next two magnetic concentrates combined and hereafter referred to as mag. conct. 2.
The nonmagnetic product produced was subjected to desliming at approximately 10 microns using a laboratory thickener-sizer apparatus to produce a plus 10 micron sized product and a minus 10 micron sized pxoduct.
The plus 10 micron product was subjected to two stages of high intensity magnetic separation using the Colburn magnetic separator with the two magnetic concentrates produced combined and hereafter referred to as magO conct. 3, and a final nonmagnetic product.
82~
The following results were obtained:
Product % Chemical Analysis - ~
Produced 123SiO2 Fe23 Tio2 L.O.I
Mag~ Conct. 1 8.0 - 2.4 74.8 1.5 Mag. Conct. 2 5.8 - 2.5 44.9 1.9 Minus 10 Microns 25.4 - 15.1 27.4 5.2 Mag. Conct. 3 2.4 - 2.5 12.0 1.8 Nonmagnetics Plus 10 Microns 58.463.1 1.7 1.8 0.8 32.6 :
Calculated Head Sample Ana:Lysis 100.050O7 4.2 16.9 2.1 26.1 10The Mag. Conct. 1, Mag. Conct. 2, and the Minus 10 Micron Products would be treated as waste. Mag. Conct. 3 would be satisfactory feed material to the Bayer Process.
The Nonmagnetics Plus 10 Microns Product is outstanding as a product for use in the chemical industry such as a premium ; 15grade fire retardant with a loss on ignition analysis of 32.6 as against a maximum possible of approximately 34.5%.
In one preferred embodiment of the invention, I
use one or more stages of desliming following my at least one stage of high intensity magnetic separation. However, dependent on the type of material and the circuitry used I may use one or more stages of desliming at any point in the circuit following my dispersion-grinding stage.
Where I use a low to medium intensity magnetic stage or desliming or both ahead of my at least one high intensity magnetic stage I can use the at least one screening stage at any point in the circuit following the dlspersion-grinding stage and prior to the at least one high intensity magnetic stage.
1 ~58202 In my one at least high intensity magnetic stage the magnetic gap width is in the range of about 0.35 millimeters to 2.0 millimeters. The width of the gap is de-termined by measuring the closest distance between opposing ridges of north and south poles and i5 well understood in the art.
The invention has been described herein with reference to certain preferred embodiments. However, as obvious variations thereon will become apparent to those skilled in the art, the invention-is not considered to be limited thereto.
Claims (19)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A process for the upgrading of an aluminum mineral bearing material selected from the group consisting of bauxites, bauxitic clays, and aluminum mineral bearing clays comprising:
(a) subjecting said material to at least one dispersion stage of wet grinding at a pulp density of about 25% to 60%
solids and in the presence of a member selected from the group consisting of sodium hydroxide alone in the pH range of about 9.5 to 12.5; sodium hydroxide in combination with an alkaline agent comprising KOH, NH4OH, Na2CO3, or mixtures thereof, in the pH range of about 9.5 to 12.5; sodium hydroxide in combination with a dispersant, lignins, silicates, phosphates, or mixtures thereof, and in the pH range of about 8.5 to 12.5; and sodium hydroxide in combination with KOH, NH4OH, Na2CO3, or mixture thereof, and a dispersant comprising lignins, silicates, phos-phates, or mixtures thereof, and in the pH range of about 8.5 to 12.5;
(b) subsequently subjecting the said pulp to at least one screening stage in the range of 10 mesh Tyler to 65 mesh Tyler to produce a minus 10 to minus 65 mesh product; and (c) subsequently subjecting the said minus 10 to minus 65 mesh product to at least one stage of high intensity magnetic separation using a field strength of about 11.0 to 22.0 kilogauss to produce a magnetic concentrate enriched in iron and titanium minerals and a nonmagnetic product impoverished in iron and titanium minerals.
(a) subjecting said material to at least one dispersion stage of wet grinding at a pulp density of about 25% to 60%
solids and in the presence of a member selected from the group consisting of sodium hydroxide alone in the pH range of about 9.5 to 12.5; sodium hydroxide in combination with an alkaline agent comprising KOH, NH4OH, Na2CO3, or mixtures thereof, in the pH range of about 9.5 to 12.5; sodium hydroxide in combination with a dispersant, lignins, silicates, phosphates, or mixtures thereof, and in the pH range of about 8.5 to 12.5; and sodium hydroxide in combination with KOH, NH4OH, Na2CO3, or mixture thereof, and a dispersant comprising lignins, silicates, phos-phates, or mixtures thereof, and in the pH range of about 8.5 to 12.5;
(b) subsequently subjecting the said pulp to at least one screening stage in the range of 10 mesh Tyler to 65 mesh Tyler to produce a minus 10 to minus 65 mesh product; and (c) subsequently subjecting the said minus 10 to minus 65 mesh product to at least one stage of high intensity magnetic separation using a field strength of about 11.0 to 22.0 kilogauss to produce a magnetic concentrate enriched in iron and titanium minerals and a nonmagnetic product impoverished in iron and titanium minerals.
2. A process according to claim 1 wherein in step the dispersion stage is conducted in the presence of ?
hydroxide alone, or sodium hydroxide in combination with an alkaline agent selected from the group KOH, NH4OH, Na2CO5, and mixtures thereof, and in the pH range of about 9.5 to 12.5.
hydroxide alone, or sodium hydroxide in combination with an alkaline agent selected from the group KOH, NH4OH, Na2CO5, and mixtures thereof, and in the pH range of about 9.5 to 12.5.
3. A process according to claim 1 wherein in step (a) the dispersion stage is conducted in the presence of sodium hydroxide in combination with a dispersant selected from the group consisting of lignins, silicates, phosphates and mixtures thereof, or sodium hydroxide in combination with an alkaline agent selected from the group consisting of KOH, NH4OH, Na2CO3, and mixtures thereof, and a dispersant selected from the group consisting of lignins, silicates, phosphates, and mixtures thereof, and in the pH range of about 8.5 to 12.5.
4. A process according to claim 1 wherein the said at least one stage of high intensity magnetic separation is carried out in a Jones type high intensity magnetic separator.
5. A process according to claim 1 wherein the said minus 10 to minus 65 mesh product is subjected to at least two stages of high intensity magnetic separation in a Jones type high intensity magnetic separator.
6. A process according to claim 1 wherein the resulting said nonmagnetic product is subjected to at least one stage of desliming to produce a fines product enriched in iron, titanium, and silica, and a coarse product impoverished in iron, titanium and silica.
7. A process according to claim l wherein the resulting said nonmagnetic product is subjected to at least one stage of desliming to produce a fines product enriched in iron, titanium, and silica and a coarse product impoverished in iron, titanium and silica and wherein following the said desliming stage, the said coarse product produced is subsequently subjected to at least one stage of high intensity magnetic separation.
8. A process according to claim 1 wherein said minus 10 to minus 65 mesh product is subjected to at least one stage of low to medium intensity magnetic separation in the range of 0.5 to 10.0 kilogauss to produce a magnetic product and a non-magnetic product; and wherein said nonmagnetic product is subsequently subjected to at least one stage of high intensity magnetic separation using a field strength of about 11.0 to 22.0 kilogauss to produce a magnetic concentrate enriched in iron and titanium minerals and a nonmagnetic product impoverished in iron and titanium minerals.
9. A process according to claim 8 wherein the said at least one stage of high intensity magnetic separation is carried out in a Jones type high intensity magnetic separator.
10. A process according to claim 9 wherein the said minus 10 to minus 65 mesh product is subjected to at least two stages of high intensity magnetic separation in a Jones type high intensity magnetic separator.
11. A process according to claim 9 wherein the said product is subjected to at least one screening stage in the range of 10 mesh Tyler to 65 mesh Tyler to produce a minus 10 to minus 65 mesh product subsequent to the said at least one stage of low to medium intensity magnetic separation.
12. A process according to claim 11 wherein dispersion step (a) is conducted by wet grinding at s pulp density of about 25% to 60% solids, and in the presence of a material selected from the group consisting of sodium hydroxide alone in the pH range of about 9.5 to 12.5; sodium hydroxide and an alkaline agent comprising KOH, NH4OH, Na2CO3, or mixtures thereof at in the pH range of about 9.5 to 12.5; sodium hydroxide in combination with a dispersant comprising lignins, silicates, phosphates or mixtures thereof in the pH range of about 8.5 to 12.5; and sodium hydroxide in combination with an alkaline agent selected from the group consisting of KOH, NH4OH, Na2CO3, and mixtures thereof, and a dispersant comprising lignins, silicates, phosphates, or mixtures thereof in the pH
range of about 8.5 to 12.5.
range of about 8.5 to 12.5.
13. A process according to claim 8 and subsequently subjecting said nonmagnetic product to at least one stage of desliming to produce a fines product enriched in iron, titanium, and silica, and a coarse product impoverished in iron, titanium and silica.
14. A process according to claim 13 wherein the said at least one stage of high intensity magnetic separation is carried out in a Jones type high intensity magnetic separator.
15. A process according to claim 13 wherein the said minus 10 to minus 65 mesh product is subjected to at least two stages of high intensity magnetic separation in a Jones type high intensity magnetic separator.
16. A process according to claim 13 wherein following the said desliming stage, the said coarse product produced is subsequently subjected to at least one stage of high ?
magnetic separation.
magnetic separation.
17. A process according to claim 13 wherein the said nonmagnetic product is subjected to at least one screening stage in the range of 10 mesh Tyler to 65 mesh Tyler to produce a minus 10 to minus 65 mesh product subsequent to the said at least one stage of low to medium intensity magnetic separation.
18. A process according to claim 13 wherein the said nonmagnetic product from the at least one stage of high intensity magnetic separation is subjected to at least two stages of desliming to produce a fines product enriched in iron, titanium and silica and a coarse product impoverished in iron, titanium and silica.
19. A process according to claim 13 wherein, subsequent to said at least one stage of wet grinding, and prior to said at least one stage of high intensity magnetic separation, the said product is subjected to at least one stage of desliming to produce a fines product enriched in iron, titanium, and silica and a coarse product impoverished in iron, titanium, and silica.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000358577A CA1158202A (en) | 1980-08-19 | 1980-08-19 | Upgrading of bauxites, bauxitic clays and aluminum mineral bearing clays by beneficiation |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000358577A CA1158202A (en) | 1980-08-19 | 1980-08-19 | Upgrading of bauxites, bauxitic clays and aluminum mineral bearing clays by beneficiation |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1158202A true CA1158202A (en) | 1983-12-06 |
Family
ID=4117690
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000358577A Expired CA1158202A (en) | 1980-08-19 | 1980-08-19 | Upgrading of bauxites, bauxitic clays and aluminum mineral bearing clays by beneficiation |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1158202A (en) |
-
1980
- 1980-08-19 CA CA000358577A patent/CA1158202A/en not_active Expired
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US4303204A (en) | Upgrading of bauxites, bauxitic clays, and aluminum mineral bearing clays | |
| US5277368A (en) | Coal cleaning process | |
| US4272029A (en) | Upgrading of bauxites, bauxitic clays, and aluminum mineral bearing clays | |
| US5143599A (en) | Process for refining kaolin | |
| US5348160A (en) | Coal cleaning process | |
| CA3012862C (en) | Beneficiation process for enhancing uranium mineral processing | |
| CN116940540A (en) | Dry beneficiation process for electrostatic separation of bauxite | |
| US4113466A (en) | Concentration of hydrated aluminum oxide minerals by flotation | |
| US4206878A (en) | Beneficiation of iron ore | |
| AU2020101235A4 (en) | Method for the Beneficiation of Iron Ore Streams | |
| CA1326571C (en) | Recovery of metal values from oil sands tailings slurry | |
| CA1158202A (en) | Upgrading of bauxites, bauxitic clays and aluminum mineral bearing clays by beneficiation | |
| AU2017100574B4 (en) | Improved uranium ore processing using hydrocyclone beneficiation | |
| GB2082554A (en) | Upgrading of bauxites, bauxitic clays, and aluminum mineral bearing clays by beneficiation | |
| CA1088226A (en) | Concentration of hydrated aluminum oxide minerals by flotation | |
| CN112718231B (en) | Mineral separation method of molybdenite of magnesium-rich mineral | |
| US4243179A (en) | Process for preparation of raw material minimizing the size degradation of anatase ore | |
| US4667885A (en) | Process for grinding organic-containing minerals | |
| EP0216002A2 (en) | Process for beneficiating natural calcite ores | |
| US2806598A (en) | Froth flotation process | |
| US3349903A (en) | Process for beneficiating unground pebble phosphate ore | |
| US4256267A (en) | Recovery of minerals from ultra-basic rocks | |
| AU662568B2 (en) | Coal cleaning process | |
| JPH06340934A (en) | Method for removing magnetic substance from alumina-containing ore | |
| AU2017203383B2 (en) | Beneficiation process for enhancing uranium mineral processing |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |