Document repV7X8or1yrg5q39ndZNNjoJ

FILE NAME: RT Vanderbilt (RTV) DATE: 1972 Dec 27 DOC#: RTV245 DOCUMENT DESCRIPTION: US Patent - Beneficiation of NYC Talc [Filed 1972, Approved Sept 24, 1974] United States Patent m Baak [il] 3,837,582 [45] Sept. 24,1974 [54] BENEFICIATION OF NEW YORK STATE TALC [75] Inventor: Tryggve Baak, Princeton, N.J. [73] Assignee: Cyprus Mines Corporation, Trenton, N.J. [22] Filed: Dec. 27,1972 [21] Appl. No.: 319,001 [52] U.S.CI........................... 241/4,241/20,241/24 [51] Int. Cl.............................................. B02c 19/00 [58] Field.of Search............... 241/4, 15, 16, 20, 21, 241/24; 209/9 [56] 3,307,790 3,346,111 3,356,211 3,599,879 References Cited UNITED STATES PATENTS 3/1967 10/1967 12/1967 8/1971 Cohn et al......................... 241/20 X Thompson et al....................... 209/9 Mathews.................................. 209/9 C la rk .........................................241/4 Primary Examiner--Granville Y. Custer, Jr. Attorney, Agent, or Firm--Woodcock, Washburn, Kurtz & Mackiewiez [57] ABSTRACT Process of beneficiating Gouverneur, New York talc ore to produce a high purity, platy talc substantially free of tremolite. The process involves crushing the ore and irradiating the crushed ore with short wave length ultraviolet radiation to cause the talc in the crushed ore to fluoresce predominantly white and the tremolite in the crushed ore to fluoresce a predomi nantly non-white color. The irradiated crushed ore is then separated into a first portion in which the fluores cent areas of the constituent rocks fluoresce predomi nantly white, and a second portion in which the fluo rescent areas of the constituent rocks fluoresce a pre dominantly non-white color. The rocks in the first por tion are crushed further preferably to a particle size of minus 100 Tyler mesh, and are subjected to at least one froth flotation step. The talc recovered from the froth formed during the last froth flotation step is characterized by a G.E. brightness about 90 and a tremolite content of less than 1.0 percent by weight. 12 Claims, No Drawings 3,837,582 1 2 BENEFICIATION OF NEW YORK STATE TALC the ore, is also capable of fluoresceing at a characteris tic wavelength after exposure to ultraviolet, X-ray, or BACKGROUND OF THE INVENTION other type of radiation. A method of rendering asbestos in asbestos- 1. Field of the Invention 5 containing rock differentially fluorescent in relation to This invention relates to the production of a high pu host rock is described in U.S. Pat. No. 3,346,111 -- rity talc, suitable for cosmetic applications, from talc ore including a high proportion of undesirable impuri ties, such as asbestos in the form of tremolite. Thompson et al. The patentees there state that when an asbestos-containing rock is dipped into a fluorescent dye solution and is washed and inspected under suit 2. Description of the Prior Art 10 able radiation, such as ultraviolet light, the exposed Since talc has many uses requiring different grades of seams of asbestos can be identified by the relative bril purity, it has been the practice to separate the talc to liance of their fluorescence. They add, however, that varying degrees from the impurities with which it is as for practical purposes the ratio of light emitted by host sociated in its natural state. The customary milling rock is not sufficiently great to enable easy identifi practice consists of grinding and sizing, beneficiation 15 cation of asbestoscontaining rocks by that method. Ac generally being obtained by hand sorting and cobbing. cordingly, they describe a process of rendering asbestos The natural floatability of talc has been advantageously in asbestos-containing rocks differentially fluorescent employed to separate the talc from gangue materials in relation to host rock by contacting the rocks with a which are associated with the talc in its ore form. liquid dispersion of a precipitated fluorescent dye and High grade talc in the form of powder has found wide 20 removing the non-sorbed material from the rocks, as by acceptance in the cosmetic industry for application to washing, sufficiently to render exposed asbestos differ human skin. For such uses, it is desirable to have the entially fluorescent in relation to host rock. The talc as free as possible of any irritating particles. Ac method described by Thompson et al. is said to be ap cordingly, in the past the highest quality talcum pow plicable to sorting of rocks containing various types of ders have been made from talc ore which, as mined, 25 asbestos, including crocidolite, chrysotile, amosite, contain no more than 4 to 5 percent of impurities, the tremolite and actinolite. remainder being substantially pure talc. See, e.g., U.S. Pat. No. 3,102,856 - Chase. SUMMARY OF THE INVENTION Certain talc ores, such for example as those found in It is a primary object of the present invention to pro the region of Gouverneur, New York, contain a sub 30 vide an economical process for the production of a high stantial proportion of undesirable impurities, notably purity talc from talc ore containing a high proportion asbestos in the form of tremolite, and such ores have of tremolite as an impurity. not in the past been economically feasible sources for The present invention is particularly suited for the the production of cosmetic grade talc. Such ores con production.of high quality talc from talc ores such, for sist of three types: tremolite talc ore, limey talc ore, and 35 example, as are found in the region of Gouverneur, green talc ore. The tremolite talc ore contains talc with New York. .Such ores in the past have not been suitable tremolite and serpentine as principal impurities; the for the production of cosmetic grade talc because of limey talc ore contains talc, both fibrous and foliated, their high proportion of impurities, notably tremolite, limestone and tremolite; the green talc ore contains fo which could not economically be separated from the liated talc, quartz, feldspar and tremolite. Froth flota 40 desired talc product. By virtue of the present invention, tion of the above-mentioned ores had been reported as a high quality talc product may be economically pro early as 1939 [J.E. Norman et al., " Froth Flotation of duced from ores whose tremolite content may in some Talc Ores from Gouverneur, New York," Bulletin instances exceed the talc content of the o,re. American Ceramic Society 18, No. 8, p. 292 (1939)]. Generally stated, this invention provides a process Although some enrichment of the talc was obtained by 45 for preparing a high quality talc from talc ore contain flotation, the tremolite residues in the cleaner concen ing a high proportion of tremolite as an impurity by trates, as reported by the authors, ran in the range of crushing the talc ore, irradiating the crushed ore with between 13 to 35 percent. Such cleaner concentrates short wavelength ultraviolet radiation to cause the talc were therefore entirely unsuitable as cosmetic grade in the crushed ore to fluoresce predominantly white talc which should be essentially free, i.e., contain less 50 and the tremolite in the crushed ore to fluoresce a pre than 1 percent by weight, of fibrous silicates, such as dominantly non-white color, separating the crushed ore tremolite and serpentine. into a first portion in which the fluorescent areas of the It is known that many minerals will fluoresce upon constituent rocks fluoresce predominantly white and a eaxnpdolsounrgewtaoveul.turlatvraiovlieotlertaldigiahttiohna,vaenbdeebnothuseshdofrotwr athvee 55 sceocnosntidtupeonrttiroonckisn fwluhoircehscteheprfelduoomreisncaennttlyarneoasn-owfhtihtee, detection of various minerals. The characteristics of crushing the first portion to a particle size of minus 20 certain minerals has also been employed as the basis for mesh, forming a dilute aqueous slurry of the crushed sorting techniques. For example, U.S. Pat. No. first portion, the slurry having a solids content prefera 2,717,293 --: Holmes describes tungsten ore sorting ap 60 bly not exceeding about 15 percent by weight of the paratus which takes advantage of the characteristic flu- slurry, subjecting the slurry to at least one froth flota orescence o f th a t m ineral w hen exposed to ultraviolet tion step, removing the froth formed during the final radiation. froth flotation step, and recovering a high purity talc The separation of ore particles which have been pref from the floated froth. erentially coated with liquid fluorescent material is de 65 The present invention takes advantage of the fact scribed in U.S. Pat. No. 3,356,211 -- Mathews. The that the talc and tremolite constituents in Gouverneur, coating liquid used in the process disclosed, in addition New York talc ore are differentially fluorescent when to being specific to particles of one of the minerals in exposed to short wavelength ultraviolet or other radia 3,837,582 3 4 tion. The talc constituent of the ore, when irradiated the type of sorting technique that is to be used. Where with short wavelength ultraviolet light will fluoresce automatic sorting machines are employed, the ore may predominantly white, in a greenish-white or cream be crushed to a particle size of less than one-half inch, white color, whereas the tremolite constituent will fluo preferably from one-eighth to one-quarter inch in size. resce a distinctly non-white color, i.e. apricot-pink to 5 orange or red. See, e.g., Warren, Minerals That Fluo resce With Mineralite Lamps, Bulletin No. 315 o f Ul Generally speaking, sorting of the crushed rock is achieved in accordance with the invention by first irra tra-Violet Products, Inc. (1969). diating the crushed rock with short wavelength radia The invention further takes advantage of the discov tion such for example as ultraviolet light characterized ery that tremolite and foliated talc are not homoge 10 by a wavelength of from about 250nm (nanometer) to neously distributed one with another in talc ore mined about 340nm. The color patterns in the rocks exposed in the region of Gouverneur, New York, but instead ap to the ultraviolet light source are quite discernible. For pear to be distributed in concentrated masses through example, under short wavelength mercury light of out the ore. Accordingly, when the ore is crushed into 254nm., the talc constituent of the ore will fluoresce a rocks of a manageable size, certain rocks will contain 15 greenish-white or cream white. The tremolite constitu more foliated talc than tremolite. By exposing the rocks ent on the other hand will fluoresce an apricot-pink to to short wavelength ultraviolet radiation in accordance orange or red. As above noted, a definite improvement with the invention, the high talc-low tremolite content may be reached optically for the dsicrimination be rocks which are predominantly suitable for subsequent tween acceptable and rejectable rocks for sorting pur crushing and flotation steps can be isolated from the 20 poses with consequent improved yields in the final remainder of the crushed ore. product by wetting the ore rocks with water prior to ex An essential feature of the present invention, which posing them to the ultraviolet light source. When the is critical to the successful separation of the tremolite moistened rocks are inspected under shortwavelength from the foliated talc and the consequent production of ultraviolet light, a substantial increase in darkness of a cosmetic grade talc product, is the combination of ul 25 the impurities is observed, while the talc shows undi traviolet sorting and froth flotation operations. In this minished whitish fluorescence. As will be appreciated connection, it has been found that froth flotation alone by those skilled in the art, numerous other light -- absent the ultraviolet sorting step -- will not afford sources, such as UV lasers active in the preferred short an economical separation of the impurities from the wavelength region (i.e. from 250 to about 340nm) may talc. 30 be used in the practice of the invention. An additional advantage of the invention is based As the sorting is conducted, whether by machine or upon the discovery that the fibrous talc constituent of by hand, crushed ore in the form of rocks is separated ore from the region of Gouverneur, New York appears into a first portion in which the fluorescent areas of the to be more associated with tremolite than with the de constituent rocks fluoresce predominantly white and a sired platy or foliated talc constituent of the ore. Ac 35 second portion in which the fluorescent areas of the cordingly, the high quality talc produced in accordance rocks fluoresce predominantly non-white. Once this with the invention is characterized by a low fibrous talc sorting step is completed, the first portion of rocks, i.e. content as well as being substantially free (i.e. contains those containing a substantial quantity of talc as op less than 1 percent and preferably less than 0.5 per posed to tremolite, are further crushed prior to flota cent) of impurities such as tremolite and serpentine. As 40 tion for the purpose of freeing the mineral particles a result, the slip or feel of the talc beneficiated in accor from each other. In this connection, it has been found dance with the process of the invention is excellent, that the rocks should be crushed to a particle size of thus rendering talc especially suitable for cosmetic ap minus 20 Tyler mesh, and preferably below minus 100 plications. mesh, or finer, to achieve the desired high grade talc The present invention further contemplates the addi 45 product. For cosmetic purposes, the ore should be tional option step of wetting the crushed talc ore with ground to a particle size of 100 percent minus 100 water, prior to irradiation and sorting, to facilitate the mesh and 98 percent minus 200 mesh. sorting operation. In this connection, it has been dis In accordance with the invention, the preferential covered that the wetting of the crushed ore with water flotation of the platy talc from the ore impurities con enhances the contrast in color between the talc and 50 tained in the crushed portion of ore rock is acheived by tremolite constituents of the ore, so that upon exposure utilizing a relatively dilute slurry having a solids content to ultraviolet radiation the discrimination between of less than about 15 percent by weight. Preferably, the those rocks which are predominantly suitable for fur solids content will be 10 or less percent by weight of the ther treatment, i.e. the rocks whose fluorescent areas slurry. It has also been discovered that particularly fluoresce predominantly white, is facilitated. 55 good results may be achieved by dispersing the ground In accordance with the invention, the crude talc ore first portion of crushed ore in deionized water. If de may be prepared for sorting by crushing the mined ore sired, a small amount of a water-soluble frother may be to a manageable particle size such, for example, as added to improve the separation of the tremolite during rocks in the general size range of under 2 inches. The 60 the froth flotation. Preferably, the amount of frother sorting of the ore rocks can then be accomplished opti added to the slurry is less than about 0.2 pound of cally by hand cobbing or with the aid of any of the pres frother per ton of solids in th e slurry. W hile any of the ently available automatic sorting machines on the mar well known, commercially available frothers may be ket, such as, for example, the Sortex 621 M Optical used, it has been found that particularly outstanding re Separator, manufactured by Sortex Company of North 65 sults can be achieved by the use of methyl isobutyl car America, Lowell, Mich., which include a shortwave ul binol or isopropanol. Other suitable frothers useful in traviolet light source. To some extent, the size of rocks the practice of the invention will readily occur to those to which the original ore is crushed will depend upon skilled in the art. 3,837,582 5 6 In accordance with a preferred form of the invention, observed that certain rocks included fluorescent areas a fairly dilute,pulp, containing less than 10 percent by which were predominantly white whereas other rocks weight of solids, is used, and is conditioned with a small included fluorescent areas which were predominantly amount of frother which may be either methyl isobutyl non-white in color and varied from a pink to orange. carbinol or isopropanol. Where isopropanol is used, it 5 The irradiated rocks were then manually separated into has been fovmd desirable to additionally add sodium sil two portions, the first portion comprising rocks in icate to the slurry to depress the tremolite and further which the fluorescent areas were predominantly white, improve separation. The slurry is then aerated and a and the second portion comprising rocks in which the first concentrate withdrawn. It has been found desir fluorescent areas fluoresced predominantly non-white. able to refloat this concentrate, without addition of any 10 A 150 pound sample of rocks from the first portion was reagents, to produce good quality talc concentrate. To then collected, micro-pulverized, and then screened assure virtually complete removal of the tremolite a through.a 200 mesh screen. The oversized materials third flotation step may be employed, although two flo were re-micro-pulverized and re-screened repeatedly tation steps are generally sufficient to provide a talc to secure 100 percent minus 200 mesh materials as flo product in which the tremolite and serpentine contents 15 tation feed. are less than 1 percent. The flotation pulp was prepared by slurrying the talc The froths may be processed in a conventional man ore in deionized water to, make up a slurry of 10 per ner by thickening, filtration, washing and drying. cent solids. To ensure complete wetting Of the tremo It has been found that upon the completion of the lite and serpentine constituents of the ore during the process combining the sorting technique involving the 20 flotation, the pulp was mixed at a high speed for at least separation of the crushed ore under ultraviolet light 30 minutes. The flotation consisted of a two stage oper and subsequent grinding and flotation steps as outlined ation, i.e. rougher flotation, and a first cleaner flota above, no traces of tremolite could be observed in the tion. Methyl isobutyl carbinol was added into the pulp talc samples produced. The samples were inspected just prior to the pumping of the pulp into the first flota using microscopic techniques, X-ray diffraction and 25 tion cell at 0.15 pounds of methyl isobutyl carbinol per X-ray spectrometry. ton of solids in the slurry. The feed rate of the pulp to As noted above, an additional advantage of the pro the rougher cell was about 45 pounds per hour. The cess of the invention is that the fibrous talc constituent feed rate of the first cleaner flotation was about 20 gal of the ore is also for the most part removed with the lons per hour. tremolite during the process of the invention. 30 The rougher concentrate was collected, re-slurried If the talc product is to be used for cosmetic pur with deionized water to make dilute pulp of about 10 poses, it may if desired be subjected to a chlorine treat percent solids to be floated in the cleaner cell. The ment to remove all micro-organisms. This is generally rougher tails were collected, filtered on a vacuum filter achieved prior to the final drying step. The subsequent and dried. The middlings from the cleaner flotation drying of the chlorinated talc product will remove the 35 step were collected, filtered and dried. The cleaner volatile chlorine from the talc. concentrate was screened through a 200 mesh screen, In order that those skilled in the art may better un derstand how the present invention may be practiced, dried, micro-pulverized and screened again. All of the minus 200 mesh concentrates were pulped in water the following examples are given by way of illustration again for sterilization with sodium hypochlorite which and without limitation. The talc used in the examples 40 was introduced at 0.2 milliters of concentrated (15 per which follow was ore obtained from the Gouvemeur, New York region. Typical chemical analyses of talcs there mined are set forth below. cent available chlorine by weight) sodium hypochlorite per liter of pulp. The sterilization was carried out over night, and the pulp was subsequently filtered and dried. Si02 MgO . Fe20 3 AIjO, CaO GeO MnO Ignition Loss water ( 105oC) CO, (1) 59.80 27.45 0.05 0.57 6.80 0.15 0.39 4.75 0.45 1.18 45 To ensure proper flotation against entrapment of un wanted tremolite, the tremolite content in the talc was (2) checked frequently with X-ray diffraction during an in 66.23 terval of one to two hours during the flotation period. 25.71 0.13 1.05 50 The recovery data are as follows: 2.26 0.22 0.16 Concentrate 64 lbs. 3.86 Middlings 33.5 0.25 Tails 38 0.56 55 Total 135.5 lbs. 47.2% 24.7 28 99.9% ( 1) Average sample o f mined tulc zone. Tulcville, G ouvem eur district. New York; Anulysis hy Glen Edgington. U S. Dept of Agriculture. See U.S Geological Survey Bulletin 1167 (2) Average sample of footwafl talc zone, Fowler, G ouvem eur district, New York; Analysis by Glen Edgington, U S.D.A See U S Geological Survey Bulletin 1167. The X-ray spectrometry analysis and physical data for the foregoing example are as follows: 60 Concentrate Middlings Tails EXAMPLE I Talc ore was ground to a particle size wherein the constituent rocks were less than about 2 inches in size. 65 The rocks were then exposed to ultraviolet radiation, and specifically to ultraviolet light having a wavelength of 254nm. Upon irradiation of the crushed ore it was % Si03 % MgO % FejOj % AljOj % CaO G.E.B. 66.13 35.30 0.06 0.25 0.05 95.0 63.08 33.75 0.12 0.25 0.64 90.6 59.95 38.24 0.21 0.25 3.05 83.6 3,837,582 7 8 EXAMPLE II from talc ore containing tremolite as an impurity, which comprises crushing the talc ore, Talc ore from the region of Gouverneur, New York irradiating said crushed ore with short wavelength ra was ground into rocks from 2 to 6 inches in size. These diation to cause the talc in said crushed ore to fluo rocks were exposed to ultraviolet radiation of a wave length as described above, whereupon certain of the rocks included fluorescent areas which were predomi nantly white, whereas other rocks fluoresced predomi nantly non-white, i.e. from pink to orange. The irradi ated rocks were manually separated into two portions as in the preceding example. The portion in which the rocks flouresced predominantly white were micropulverized to minus 200 mesh in size, and flotation was accomplished as in the previous example. The recovery data are as follows: resce predominantly white and the tremolite in said crushed ore to fluoresce a predominantly nonw hite color, separating said crushed ore into a first portion in which the fluorescent areas of the constituent rocks fluoresce predominantly white and a second portion in which the fluorescent areas of the con stituent rocks fluoresce predominantly non-white, crushing said first portion to a particle size of minus 20 mesh, forming a dilute aqueous slurry of said crushed first Weight Talc lb. % (1) Serpentine Weight % Wtflght Tremolite % Weight Crude Ore 300 30 90 37 111 33 99 U-V Sorted Concentrate 100 69 69 17.3 17.3 13.7 13.7 Flotation Concentrate 48 99 47.5 0.24 0.5 0.24 0.5 Flotation Waste 26 50.6 12.4 27.6 7.2 21.6 56 Flotation Middlings 26 32.9 9.1 37.3 9.7 29.6 7.7 (1) The talc composition is noted as total talc, both platy (foliated) and fibrous. In the flotation con centrate, it is estimated that about 98% of the talc is foliated but in the crude ore only % or less may be of the foliated type. The present invention thus affords an improved pro cess for economically producing high grade talc, such for example as may be used in cosmetic applications, from talc ore of the type mined in the Gouverneur, 35 New York region which is characterized by relatively high contents of tremolite and serpentine and which, heretofore could not be economically beneficiated to a purity level required for cosmetic applications. The high quality talc product produced by the process of 40 the invention is also characterized by an improved lu bricity as a result of its high platy talc content and a low content of fibrous and granular talc. In addition to being substantially free of tremolite, i.e. having less than 1 percent by weight of tremolite impurity, the final 45 talc product produced in accordance with the process of the invention is characterized by a G.E. brightness of at least 90, excellent fragrance retention and excel lent slipperiness and shine characteristics. The normal cosmetic grind of talc produced in accordance with the 50 invention can also be used as a dry lubricant of white color in place of graphite or molybdenum disulfide, both of which have adverse colors. In addition, talc produced by the process of the invention may also be used in the preparation of paint, paper, textiles, ce 55 ramic compositions, rubber, plastics, and various other applications well known to those skilled in the art. It should be understood that while the present inven tion has been described in considerable detail with re spect to certain specific embodiments thereof, it is not 60 to be considered limited to those embodiments, but may be used in other ways without departure from the spirit of the invention or the scope of the appended claims. 65 What is claimed is: 1. A process for the preparation of a high purity talc portion, said slurry having a solids content not ex ceeding about 15 percent by weight of said slurry, subjecting said slurry to at least one froth flotation, removing the froth formed during the final froth flo tation step, and recovering a high purity talc from said floated froth. 2. The process of claim 1 in which the aqueous slurry is formed by dispersing said first portion of crushed ore in deionized water. 3. The process of claim 1 including the step of adding a frother to the slurry to improve the separation of the tremolite from the talc during the froth flotation. 4. The process of claim 3 in which said frother is se lected from the class consisting of methyl isobutyl car binol and isopropanol. 5. The process of claim 3 in which the amount of frother added to said slurry is less than 0.2 pound of frother per ton of solids. 6. The process of claim 1 including the step of wet ting said crushed ore with water to enhance the con trast in color between the talc and the tremolite constit uents of said ore upon exposure to ultraviolet radiation thereby to facilitate the discrimination between rocks to be separated into said first portion and rocks to be separated into said second portion. 7. The process of claim 1 in which the radiation di rected at said crushed ore is characterized by a wave length of from about 250nm to about 340nm. 8. The process of claim 1 in which the talc ore is crushed into rocks under 2 inches in size prior to said irradiation. 9. The process of claim 1 in which said first portion is crushed into a particle size of minus 100 mesh. 10. The process for the preparation of a high purity platy talc from Gouverneur, New York talc ore includ- 3,837,582 9 10 ing platy talc, fibrous talc, and tremolite as an impurity, an amount of less than 0.2 pound of frother per ton which comprises of ore, crushing the talc ore, subjecting said slurry to at least two consecutive froth irradiating said crushed ore with ultraviolet radiation flotation steps, characterized by a wavelength of from between 5 removing froth formed during the final froth flotation 250 and 340nm to cause the talc in said crushed step, and ore to fluoresce predominantly white and the trem recovering from said floated froth a high purity platy olite in said ore to fluoresce predominantly non talc characterized by a G.E. brightness of at least white, 90 and a tremolite content of less than 1.0 percent separating said irradiated crushed ore into a first por 10 by weight. tion in which the fluorescent areas of the constitu 11. The process of claim 10 in which the frother is se ent rocks fluoresce predominantly white and a sec ond portion in which the fluorescent areas of the lected from the class consisting of methyl isobutyl car constituent rocks fluoresce predominantly non binol and isopropanol. white, 15 12. The process of claim 10 including the step of wet crushing said first portion into a particle size of minus ting said crushed ore with water prior to said irradiation 100 mesh, to enhance the contrast in color between the talc and forming a dilute aqueous slurry of said crushed first the tremolite constituents of said ore upon irradiation portion in deionized water, said slurry having a thereby to facilitate the discrimination between rocks solids content not exceeding about 15 percent by 20 to be separated into said first portion and rocks to be weight of said slurry and including a frother to im prove the separation of tremolite from the talc in separated into said second portion. *** ** 25 30 35 40 45 50 55 60 65