CA2184538A1 - Removal of radionuclides from titanium bearing ores - Google Patents
Removal of radionuclides from titanium bearing oresInfo
- Publication number
- CA2184538A1 CA2184538A1 CA002184538A CA2184538A CA2184538A1 CA 2184538 A1 CA2184538 A1 CA 2184538A1 CA 002184538 A CA002184538 A CA 002184538A CA 2184538 A CA2184538 A CA 2184538A CA 2184538 A1 CA2184538 A1 CA 2184538A1
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- Prior art keywords
- bearing material
- titanium bearing
- ore
- mineral acid
- percent
- Prior art date
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- Abandoned
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Classifications
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B34/00—Obtaining refractory metals
- C22B34/10—Obtaining titanium, zirconium or hafnium
- C22B34/12—Obtaining titanium or titanium compounds from ores or scrap by metallurgical processing; preparation of titanium compounds from other titanium compounds see C01G23/00 - C01G23/08
- C22B34/1204—Obtaining titanium or titanium compounds from ores or scrap by metallurgical processing; preparation of titanium compounds from other titanium compounds see C01G23/00 - C01G23/08 preliminary treatment of ores or scrap to eliminate non- titanium constituents, e.g. iron, without attacking the titanium constituent
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B34/00—Obtaining refractory metals
- C22B34/10—Obtaining titanium, zirconium or hafnium
- C22B34/12—Obtaining titanium or titanium compounds from ores or scrap by metallurgical processing; preparation of titanium compounds from other titanium compounds see C01G23/00 - C01G23/08
- C22B34/1236—Obtaining titanium or titanium compounds from ores or scrap by metallurgical processing; preparation of titanium compounds from other titanium compounds see C01G23/00 - C01G23/08 obtaining titanium or titanium compounds from ores or scrap by wet processes, e.g. by leaching
- C22B34/124—Obtaining titanium or titanium compounds from ores or scrap by metallurgical processing; preparation of titanium compounds from other titanium compounds see C01G23/00 - C01G23/08 obtaining titanium or titanium compounds from ores or scrap by wet processes, e.g. by leaching using acidic solutions or liquors
- C22B34/1245—Obtaining titanium or titanium compounds from ores or scrap by metallurgical processing; preparation of titanium compounds from other titanium compounds see C01G23/00 - C01G23/08 obtaining titanium or titanium compounds from ores or scrap by wet processes, e.g. by leaching using acidic solutions or liquors containing a halogen ion as active agent
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B60/00—Obtaining metals of atomic number 87 or higher, i.e. radioactive metals
- C22B60/02—Obtaining thorium, uranium, or other actinides
- C22B60/0204—Obtaining thorium, uranium, or other actinides obtaining uranium
- C22B60/0217—Obtaining thorium, uranium, or other actinides obtaining uranium by wet processes
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- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Geology (AREA)
- Environmental & Geological Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Manufacture And Refinement Of Metals (AREA)
- Inorganic Compounds Of Heavy Metals (AREA)
Abstract
An improved process for beneficiating a titanium bearing material which comprises the steps of reductively roasting the titanium bearing material followed by leaching in a mineral acid leach, wherein the improvement comprises subjecting the titanium bearing material to a heat treatment in an aqueous solution of a mineral acid to remove radionuclide impurities before reductive roasting.
Description
REMOVAL OF RADIONUCLIDES FROM TlIANIUM BEARING ORES
BACKGROUND OF l~i~ INVENTION
1. Field of the Invention This invention provides an improved method for purifying tit~ninm bearing m~tPri~l~
which contain numerous impurities. More spe~ifi~lly, it relates to a process for removing radionuclide co"-pollel,t~ from lil~ni~ bearing ores and other m~tçri~l~
s 2. Description of the Prior Art The purified tit~nillm bearing m~tPri~l~ produced by the method of this invention can be used to make l;f~niu~ tetrachlori~le, which is widely used as a starting m~t~ri~l for producing tit~nillm dioxide pigmPntS, metallic liL~n~ and organo lit~nil~,. co,ll~ounds.
Cullelltly, approxim~tPly 75 percent of the tit~nium minerals produced in the world are 10 utilized by the pigmPnt~ industry in Ii~ -,.. dioxide form. In general, Iil~ .,.. te~r~rhlori~e is produced by a flllitli7~tion chlorin~ting process which comprises reacting a benP-fici~ted lllll bearing m~tPri~l with chlorinP gas at from about 800C to about 1200C in a chlorinator in which the m~tPri~l is ...~inl~ d in a flui~1i7ed state. In the chlorin~tion process, benpfici~tpA ore is used which generally contains from about 55 to about 96 percent 5 lil~ Yid~P The type m~tPri~l benPfici~tP~ the nature of the impurities in the raw m~tPri~l, and the bemPfici~tion process employed, will all inflllPnce the final con~ontration of the lil;1l~illlll dioxide in the benP-fici~t~P~ ore that is used in the rhlorin~tion process.
Known benefici~tion processes have been developed, and are generally errecliv~, to remove co,,ve~ n~l metallic impurities such as iron from tit~nillm bearing ores.
20 RPnPfit~i~tion plVcesses are not known, however, that are capable of ~ti~f~tcrily and economically ~ulirying li~;~nil.~.. dioxide ores which contain r~-iit)nlJcli~e impurities such as 2 1 ~45~8 thorium and u~ ... These impurities cannot be readily removed by cO~I~f nlionql chemic or l,.e~h~ni~ql me ns, and present a substantial health risk and risk to the envilo....,~-nl Being able to remove ra~ nu~lide impurities efflciently would be highly desirable because known sources of l;tiln;UIII be ring ores not cQr.l~ such ill~uliLies are s increasingly becoming scarce and expensive. Conv~ely, there exist large bodies of rich, int~Ypçn~ive ilmPnite and carbonated anatase ores which contain such impurities.
Many processes are known for bçn~fici-qting LiL~iîer~us ores, and ~re~ifiGqlly ilmPnite FYqmrles of such processes are disclosed in Von Bichowsky U.S. Patent No. 1,902,203, Dawson, etal., U.S. PatentNo. 2,127,247, PikeU.S. PatentNo. 2,903,341, o and ArqmPn~iq et al., U.S. Patent No. 3,457,037. The processes di~rlosed in these patents include the steps of reduction and l~q~hing. Depent1ing upon the arnount of re~uctinn, the iron colllpoullds originally contqinPd in the ilm~nitP, i.e., ferric and ferrous oxide, are reduced in various amounts to ferric and ferrous oxide and metallic iron. During the subsequent l~hing step, the iron values are solubilized in varying ~mount~, leaving a residue which is rich in ~ hi~llll dioXi(le The bulk of l;li1nil"" ores today are benPfici~t~d by the hydrochlori-~ acid l~ching process before undergoing chlt)rin~tion Rec~llse iron is the most prevalent and sul,~Li~lLial illl~ulity in nearly every lil;.ni,.." bearing ore mined today, the prin~ip~l obje~;Live of the hydrochloric acid le~ching process is to remove iron impurities from the ore. The 20 hydrochloric acid le~ching process for ilm.onite ore involves four major steps as follows:
(1) Pre-le~ching treatment of ilm~onite ore. Generally, this involves a reductive roasting of the ore at a ltlll~alure of from about 700C to about 1200C. The reduct~nt used can be solid (such as coal, coke), or liquid (such as fuel oil) or gaseous (such as hydrogen, carbon monoxide), or a mixture of such reduct~nfc 2 ~ 8~538 The degree or reductic~n can be partial -- just to reduce most of the ferric iron in the ore to the ferrous state. It can also be substantially complete -- to reduce most of the iron value all the way down to metallic iron.
In some processes, a pre-oxid~tion roasting to convert most of the iron value to the s ferrous state is employed prior to the reductive roasting step.
(2) Hydrochloric Acid T ~ hing. Pre-treated ore such as ilmPnitr is mixed with a suitable amount (generally from about 15 percent to about 30 percent in excess of the stoichiometric l~ui~-l-ent) of hydrochloric acid in a vessel where the reaction to dissolve the iron value and other impurities takes place with added heat and a suitable form of stirring 10 or a~it~tion of the conlenl~
A common concentration of the acid used is from about 18 percent to about 20 percent HCl, which is the usual conce~ l;on of the acid l~gen~ PA from the mother liquor.
Other concentrationc may be used, although they may not be economical. T~rhing le".~ c may range from about 100C to about 150C, for a l~rhinE period of from S about six to about foullæn hours.
TP~rhin~ may be accomplichPd in one or more stages, batch or contimlQus~ and at ~1 .-os~h~- ;c plC,Salll~ or greater, e.g., up to 50 PSIG. The total amount of hydrochlorit~. acid used in all stages generally is from about 2 to about 3.8 parts per weight thereof per one part by weight of the ilmrnite ore. When the desired degree of l~rhing is achieved, the mother 20 liquor is s~ ed by con~e~.~ion~l means from the solid residue. The former is ll~ s~led to the acid l~en~ ;on system for the lcgencl~tion of HCl, while the latter is washed with water to pr~rtir~lly free it from the mother liquor prior to c~lcin~ti~n (3) C~lrin~tinn of TP~hed Tlmtonite The wet solid residue after washing is c~lrin~.d under a ~ tn.e of from about 700 to about 1200C. The product, benPfici~tPd ilmPnitP or synthetic rutile, usually contdin~ from about 90 percent to about 95 percent l;l~n;-~.. dioxide ~epçn~ling on the col.lpGsilion of the original ilmenite used.
BACKGROUND OF l~i~ INVENTION
1. Field of the Invention This invention provides an improved method for purifying tit~ninm bearing m~tPri~l~
which contain numerous impurities. More spe~ifi~lly, it relates to a process for removing radionuclide co"-pollel,t~ from lil~ni~ bearing ores and other m~tçri~l~
s 2. Description of the Prior Art The purified tit~nillm bearing m~tPri~l~ produced by the method of this invention can be used to make l;f~niu~ tetrachlori~le, which is widely used as a starting m~t~ri~l for producing tit~nillm dioxide pigmPntS, metallic liL~n~ and organo lit~nil~,. co,ll~ounds.
Cullelltly, approxim~tPly 75 percent of the tit~nium minerals produced in the world are 10 utilized by the pigmPnt~ industry in Ii~ -,.. dioxide form. In general, Iil~ .,.. te~r~rhlori~e is produced by a flllitli7~tion chlorin~ting process which comprises reacting a benP-fici~ted lllll bearing m~tPri~l with chlorinP gas at from about 800C to about 1200C in a chlorinator in which the m~tPri~l is ...~inl~ d in a flui~1i7ed state. In the chlorin~tion process, benpfici~tpA ore is used which generally contains from about 55 to about 96 percent 5 lil~ Yid~P The type m~tPri~l benPfici~tP~ the nature of the impurities in the raw m~tPri~l, and the bemPfici~tion process employed, will all inflllPnce the final con~ontration of the lil;1l~illlll dioxide in the benP-fici~t~P~ ore that is used in the rhlorin~tion process.
Known benefici~tion processes have been developed, and are generally errecliv~, to remove co,,ve~ n~l metallic impurities such as iron from tit~nillm bearing ores.
20 RPnPfit~i~tion plVcesses are not known, however, that are capable of ~ti~f~tcrily and economically ~ulirying li~;~nil.~.. dioxide ores which contain r~-iit)nlJcli~e impurities such as 2 1 ~45~8 thorium and u~ ... These impurities cannot be readily removed by cO~I~f nlionql chemic or l,.e~h~ni~ql me ns, and present a substantial health risk and risk to the envilo....,~-nl Being able to remove ra~ nu~lide impurities efflciently would be highly desirable because known sources of l;tiln;UIII be ring ores not cQr.l~ such ill~uliLies are s increasingly becoming scarce and expensive. Conv~ely, there exist large bodies of rich, int~Ypçn~ive ilmPnite and carbonated anatase ores which contain such impurities.
Many processes are known for bçn~fici-qting LiL~iîer~us ores, and ~re~ifiGqlly ilmPnite FYqmrles of such processes are disclosed in Von Bichowsky U.S. Patent No. 1,902,203, Dawson, etal., U.S. PatentNo. 2,127,247, PikeU.S. PatentNo. 2,903,341, o and ArqmPn~iq et al., U.S. Patent No. 3,457,037. The processes di~rlosed in these patents include the steps of reduction and l~q~hing. Depent1ing upon the arnount of re~uctinn, the iron colllpoullds originally contqinPd in the ilm~nitP, i.e., ferric and ferrous oxide, are reduced in various amounts to ferric and ferrous oxide and metallic iron. During the subsequent l~hing step, the iron values are solubilized in varying ~mount~, leaving a residue which is rich in ~ hi~llll dioXi(le The bulk of l;li1nil"" ores today are benPfici~t~d by the hydrochlori-~ acid l~ching process before undergoing chlt)rin~tion Rec~llse iron is the most prevalent and sul,~Li~lLial illl~ulity in nearly every lil;.ni,.." bearing ore mined today, the prin~ip~l obje~;Live of the hydrochloric acid le~ching process is to remove iron impurities from the ore. The 20 hydrochloric acid le~ching process for ilm.onite ore involves four major steps as follows:
(1) Pre-le~ching treatment of ilm~onite ore. Generally, this involves a reductive roasting of the ore at a ltlll~alure of from about 700C to about 1200C. The reduct~nt used can be solid (such as coal, coke), or liquid (such as fuel oil) or gaseous (such as hydrogen, carbon monoxide), or a mixture of such reduct~nfc 2 ~ 8~538 The degree or reductic~n can be partial -- just to reduce most of the ferric iron in the ore to the ferrous state. It can also be substantially complete -- to reduce most of the iron value all the way down to metallic iron.
In some processes, a pre-oxid~tion roasting to convert most of the iron value to the s ferrous state is employed prior to the reductive roasting step.
(2) Hydrochloric Acid T ~ hing. Pre-treated ore such as ilmPnitr is mixed with a suitable amount (generally from about 15 percent to about 30 percent in excess of the stoichiometric l~ui~-l-ent) of hydrochloric acid in a vessel where the reaction to dissolve the iron value and other impurities takes place with added heat and a suitable form of stirring 10 or a~it~tion of the conlenl~
A common concentration of the acid used is from about 18 percent to about 20 percent HCl, which is the usual conce~ l;on of the acid l~gen~ PA from the mother liquor.
Other concentrationc may be used, although they may not be economical. T~rhing le".~ c may range from about 100C to about 150C, for a l~rhinE period of from S about six to about foullæn hours.
TP~rhin~ may be accomplichPd in one or more stages, batch or contimlQus~ and at ~1 .-os~h~- ;c plC,Salll~ or greater, e.g., up to 50 PSIG. The total amount of hydrochlorit~. acid used in all stages generally is from about 2 to about 3.8 parts per weight thereof per one part by weight of the ilmrnite ore. When the desired degree of l~rhing is achieved, the mother 20 liquor is s~ ed by con~e~.~ion~l means from the solid residue. The former is ll~ s~led to the acid l~en~ ;on system for the lcgencl~tion of HCl, while the latter is washed with water to pr~rtir~lly free it from the mother liquor prior to c~lcin~ti~n (3) C~lrin~tinn of TP~hed Tlmtonite The wet solid residue after washing is c~lrin~.d under a ~ tn.e of from about 700 to about 1200C. The product, benPfici~tPd ilmPnitP or synthetic rutile, usually contdin~ from about 90 percent to about 95 percent l;l~n;-~.. dioxide ~epçn~ling on the col.lpGsilion of the original ilmenite used.
(4) Regenerdtion of Hydrochloric Acid. The mother liquor, conti~;n;l-g mainly water, iron chloritles and some free HCl, is "spray roasted" in the pl~.Sence of air whcrel~y S the iron chlori~Ps are converted into HCl and to iron oxide. The lcgen~ dlcd HCl is absorbed in water to form about 18-20% HCl and recycled back into the l~P~`hjng step. The iron oxide is a by-product.
Other plucesses are known as ~ltPrn~tives or improvements of the foregoitlg process for the removal of iron and other metallic values from t;l~niln.. bearing ores.
U.S. Patent No. 4,176,159 discloses a process for the removal of impurities from rutile, ilmPnite~ and leucoxene ores. The process lclui.~s high tclllpclalulc c~lcining~
cooling, reducing, cooling, magnetic sep~r~tinn, mineral acid l~P~ching, nP,Utr~ ing~ and washing.
U.S. Patent No. 4,562,048 iicrloses the bPnPfini~ti~m of ~i~,Çe~us ores by lP~ `hillg S with a mineral acid. The telll~ldlulc used is 120-150C, and the plC.~;~lll`C used is 10-45 pounds per square inch gauge ("PSIG"). An e~Pnti~l aspect is the venting of water vapor genPr~ted during the lP~hing process. Prior to lP~ching, the ore is reduced at about 600-1100C.
U.S. Patent No. 4,321,236 discloses a process for bPnPfi~i~ting titaniferous ore. The process ~cyu~s pre-heating the tit~nPf~Prous ore and a mineral acid prior to the lP~Ching oper~tion. The t~n~lx~Atll~c is .~hllil;npd at 110-150C, and the pres~.llc is ...~h.~;.inP~ at 20-50 PSIG. For ores co~ h~ing iron in the ferric state, reductive roasting at about 800-1100 is suggested prior to lP~hing.
U.S. Patent No. 4,019,898 discloses the ~ldition of a small amount of sulfuric acid to the leach liquor used to ben~firi~tr ilmenitç ore. The te~.lpf ,~ ~ used is 100-150C, and the p~ e used is up to 50 PSIG. For ores conl;d~ g iron in the ferric state, the ore is reduced prior to le~çhing at a tcm~cldlulc of about 700-1200C.
s U.S. Patent No. 3,060,002 dicrloses acid lr~rhing of ilm~nite and Sorel slag at lcl~lpcldtule of 150-250C. Prior to l~çhin~, the ore preferably is roasted oxidatively at about 500-1,000C.
U.S. Patent No. 4,038,363 discloses upgrading of tit~nillm values in a slag such as Sorel slag by roasting with an aLkali salt, lr~rhing with sulfuric acid in two stages, and c~lnining.
Japanese Patent No. 48,102,712 discloses dephosph- ri7~tion of !il~n;~.... cc r~nl~i~t~ S
using caustic alkali after prior removal of iron.
Japanese Patent No. 87-33058/47 diccloses production of rutile type ~ n;u~ dioxide solids by heat treating hydldted ~ oxide and alkali metal hydroxide and m~tllring in 5 hydrochloric acid aqueous solution.
These prior art pfocesses do not have as an objective the removal of r~lionllr-lide impurities such as thorium and ~ n;~ and do not teach the removal of r~ionurlidçs These known mçthodc have, in fact, proven in~rre~;~iYe to substantially reduce r~-lionucli-le conr~ntr~ti~nC in t;li.n;l~." bearing ores having cignifi~nt conren~tions of p-lionl~rlides.
20 Since r~dio~cl;vily must be minimi7çd in order to reduce health effects from the use of a ~ n;u... bearing m~tPri~l with radinnllçlide impurities, standard col~ e guid~linpc on radioactivity require synthetic rutile to contain no more than 100 ppm thorium and ...,u.;l~
This is typically accomplichçd by mixing a bPnrfiri~trd ore that is high in thorium and Ul An;~llll with another ore that is low in thorium and uranillm Several l~cel.lly issued patents 2 1 845~i8 have also been directed toward improving r~ nu~lidp removal effiriPnçiPs in lil~n;~
bearing ore benPfici~tinn processes.
U.S. Patent No. 5,181,956 lic~los~Ps a process for removing r~ mlçlid~Ps from tit~ninm bearing ore which comprices reductive roasting followed by a lP~çhing step, which s employs a mineral acid having a concPntration of about 3-30% by weight at a ~I~.pelaLule of about 160-300C, until the desired amount of impurities are soluh~ili7~ and a le~h~tP
is forrned, and then removing the le~h~te from the product of the cont~cting step. The process disclosed by U.S. Patent No. 5,181,956, has the obvious disadvantage of taking place after a reductive roast and under severe con-litionc that can quickly destroy or o degenPratP process equipment.
U.S. Patent Nos. 5,011,666 and 5,085,837 disclose a process for removing radionuclides from ~ ;lllll bearing ore concictin~e escPnti~lly of subjecting the ore to two or more lP~çhing tre~tmp-ntc7 said l~çhing llc~lln~nl~ ~ltPrn~ting beLwæn use of an aqueous solution of a mineral acid and an aqueous solution of an alkaline metal col--~oul d selected 5 from the group consisting eccPnti~lly of alkaline metal ca,bonatcs, hydroxides or Il~i~Lulc5 thereof. The plocesses ~licrlosed by U.S. Patent Nos. 5,011,666 and 5,085,837, do not adequately solve the problem of ra~ n~lçlidP removal because they require too many steps, and much ill~esLm~,lt in and reconfiguration of process e~Luip---ent.
It has been found that if an ore is reduced at high lc~lpcl~t~ s to convert iron oxides 20 to metallic iron, and then the iron is removed from the pores in the ore particles by a non~gressive reaction such as aer~tion in a 0.3 molar solution of ~",...~n;~.... chloridP at ~mbient ~ellll P.~llllle to rust the iron, thorium is not removed from the surface of the ore.
The thorium or other r~ionuçlide ends up in the benPfic i~tP~ ore. Based on these results it would appear that a more aggressive reaction would be needed to erre~lively remove the 2i8~
r~dionucli~e impurities. Indeed, U.S. Patent No. 5,181,596 discloses just such a method, by dicclo~in~ a process of a reductive roast followed by an acid lP~hing process at an elevated l~ pf ~ e belw~ll 160C and 300C to errec~ively remove the r~rlinnuc1i~e impurities and to produce a s~lfficiently pure bPnefi~i~te~ ore.
SUMMARY OF THE INVENTION
It has been unexpectedly found, however, that the efficiency of ra-lionuçli~e removal in a li~niulll bearing m~ten~l benification process can be s,lls~lliaUy h~lyluved by subjecting the ~ nill.ll bearing m~tPri~l to a prelimin~ry l~chin~ step, prior to reductive roasting, under mild conditions in a mineral acid bath, sep~r~ting the mineral acid from the ore, and thereafter prDce~sing the ore according to any benifiç~tio n process known to reduce the impurities ren ~ining in the ~ i"ln bearing m~te i~l According to this invention, there is provided a process for purifying ti~ ,lll ore and removing r~ nu~lide impurities therefrom, comrri~ing~ prior to reductive roasting, lP~ching the ore adv~l~geollsly at ,no5~,hP ic p~lS~ and at a tel-lpel~lule range from about 100C to about 110C, preferably at about 105C in a mineral acid bath, of optimally 18 percent hydrochloric acid by weight, thereby solllbili7ing the ra~ionucli-le values in the ore; s~ ling the mineral acid solution and solubilized r~-lionucli-lPe impurities from the ore; and further pl~)ces~ing the ore according to benPfic~tion p~ocesses known to remove rt-"~ining impurities such as iron.
In accordallce with this invention, it has been found that the aforem-ontioned radio~lu~ P impurities can be readily reduced to an acceptable level, especi~lly when producing tit~nillm dioxide by the chlorid~ process. It also has been found that (1) relative to commercially available acids, dilute acids often can be used for the ore pre~ -hing step which are less èxpensive and produce less amounts of waste streams than strong acids; and (2) mineral acid used in the ore prPlP~(hing step can be bPnefiri~lly reused as the acid in a subsequent acid lF~ching step if called for by the benFfici~ting process ~ ~' ",ed, which reduces the problem of disposing or legenF, 1;ng such acids. Finally, the process of this invention is highly useful and desirable because it will make pra-ti~l the utili7~tion of low-grade, inF pPn~;ve and more abundant ~ ;ulll dioxide ore which cQ~ nc r~-iionuçli~e s impurities. The process is also simple and requires few steps.
DESCRIPIION OF THE DRAWING
Fig. 1 depicts a treatment process employing the subject invention in a typical titaniferous benPfit~i~tion process.
DETAILED DESCRIPTION OF lH~; PREFERRED EMBODIMENT
The process of this invention can be practiced on any tit~nium bearing m~teri~l in any form, in~ ding anatase, ilmFnite and rutile. Preferred m~tPri~l~ are li~ifeluus, such as ilmPnite, titaniferous hem~tite, and titaniferous m~g1l~PtitP~ F~pPri~lly prerelr~d is ilmenitç. Re~ e radion~ e impurities are most commonly ~o~i~tPd with ~ elv~ls ores such as ilmPnite, leuco~rPnP, rutile, perovskite, and sphene, the process can advantageously be applied to reduce ra-lionu~lide levels in these ores. As used herein, the term "ore" in~lud~ps raw ore and benPfi~i~tes and d~iv~ s thereof such as slag, blowover fines from lit~nh~" dioxide rhlo.;,-~t~ , or other process streams from a l;~nill", dioxide m~nufaçtl-ring process. The terms l;l;tn;~llll dioxide ore, I;l~n;lllll bearing ore, and l;l~n;
bearing m~teri~l, are all used inlerchallgeably.
An ore from western Al~strali~ known col,llllercially as TiWest ore is a typical l;l;,n;lJ-" bearing ore that can be pr~is~d ben~fi~ lly according to this invention. Such ore has the disadvantage of having a high concpntr~tion of thorium -- ranging from about 120 to about 170 ppm by weight. Thorium distributes itself bt;lwæn the synthetic rutile and iron oxide products from the synthetic rutile process. Such ore normally con~ c less than about 10 ppm 1l~
Though the process of this invention is generally ~rr~;~ive to remove ra~ nl-çli~içs from all sizes of ore, the present invention is particularly err~;~ive for plvcesaing ores havin s a particle size of from about 200 to about 20 mesh.
The impurities which can be removed in accordance with the process of this invention include but are not limited to radionuç~ Ps such as thorium and UldlliUlll. The process of this invention can be employed singularly to remove only the r~-lionu~ P i,lll)ulities from the base m~tPri~l, or can be pelrol",ed in conjunction with known benPfi~i~tion plucesses to remove other i~pulilies, such as, for e~mple, iron, pho~holus, ~11l-.. ;--l~- ., m~n~n~se, c~lcil~m) barium, sl,o"liu"" chr~""iu"" v~n~ -m, yttrium, and l~nth~ni~P e1~m~ntC such as l~n~ nll.", cerium, and neody,l,iu"l. FY~mrlçs of benPfiçi~tion pn~cesses to remove these elem~Pnt~ are identifi~d in the background section of this spPcifiç~tion~
The invention compri~es l~çhing the ~ ,;ll.., bearing m~tPri~l in a mineral acid leach 5 prior to reductive roasting. Preferably the acid leach is pelroll"ed as the first step of a known bemPfi~ tit n process. A co,~ ing~ sizing, or ~rin-ling process may be employed before the acid leach, to obtain the most erreclively sized and shaped ore particles. Fig. 1 shows the initial step to remove the r~diomlcli~e impurities from a ~ ;l,.., bearing ore stream 11 taking place in step 12 before any roasting or le~hing of the m~tPri~l to remove 20 other impurities in the ore as in steps 15 and 17.
The inventive le~hing step 12 takes place at a te",p~ldt~ie and pl~sau~e, and for a time, which is suMt~ient to solubilize a~a~ultially the radi(nllçli~e impurities present.
Ordinarily, the time le~luilt;d will be at least about 1 hour. Typical ranges of time are from about 1 hour to about 6 hours, p~Çeldbly from about 3 hours to about 6 hours, and most - 2 1 8~8 pl~eÇcldbly about 5 hours to about 6 hours. The lclllp~l~lulc will advantageously be from about 100 to less than about 160C, preferably from about 100 to about 110C, and most preferably at about 105C, the boiling point of 18 percent hyd~ucllloric acid at ~tmosphPric pfes~.~rc. Although trç~tmPnt~ at lclllpeldlul~s greater than 160C have also proven err~clive s to remove r~diomlçlides, operation of process equipment at greater than 160C leads to rapid equipment dege~ ir,n The pre~ -y lr~çhing step 12 can be pclÇoll~ed at about ~tmnSph~Prir plCS~UlC.
~d-lition~l pre~nri7~tirn can be added, if desired. Preferably, the ples~.-rc range will be from about 1 to about 5 atmospheres absolute, and most preferably at at~llo~llclic p~cs~..re.
10 The le~çhing can be pe,ro,llled in one or more digestions, based on the desired rate of removal of r~ionuçli~e impurities, and the desired end c~nr-ontr~ti-n of r~-lion~ e impurities in the ore.
It has been found that the lcll-pcl~ure and pres~urc of the process step 12 should preferably be ...~in~i.inPA at about the boiling point of the leach liquor. It is believed that boiling the leach ensures mixing of the ore and leach, and f~rilit~t~s in~ .rlisn and reaction between the acid and r~ionllrlide colllpollel-t~. Operation of the in~,enlivc le~ching step at the mineral acid boiling point adds the further advantage that the te~ C iS ill!~llffiri~P.nt to attack the lit:~nilllll portion of the ore to any ~ ultive extent. In this manner the ore is best plcs~lvcd for more effective p,ocessing by, for eY~mple, a succe~ive reductive roasting and lP~rhing process to remove fe~ ining impurities as shown in Figure 1, steps 15 and 17.
Operation of the ill~.,ltiVC le~hing step at the mineral acid boiling point also has the advantage that it does not induce the ~ignific~ntly harsh conrlition~ that can cl~PtPril~ratP
process e luiylllent.
2 1 8453~
It has also been found that by sepaldling the radiomlçlide col-lponenls from the ore before further agg.~ssive trP~tmPnt~ such as reductive roasting, the r~dionllç1idPs are more effectively and completely removed from the tit~nium bearing m~tPri~l The lP~`h~tP can be removed by any suitable means, incl~l~ing filtrating, dec~nting, centrifuging, or use of a s hydroclone or c~ ifiPr. DepPn~ing on the process employed, wash water or very dilute HCl solution can be used to wash the ore.
A substantial benefit can be realized from this invention by reusing th~e acid sollltil~n sep~dted from the ore in the initial lP~hing step, as illustr~tP~d by Stream 14 in Figure 1.
Reca~lse very little of the ore other than the radionuçlide content is ~tt~Ç~P~ at the mndPr~tP
10 telll~ldlure and pres~u~e employed in the initial lP~ehing step the acid removed from the initial leach should be nearly the same concentration as when it was originally introduced to the kP~hing step, without having gone through extensive regeneration tre~tmPnt This acid solution may, therefore, be introduced into a subsequent lP~hing step without any proce~ing. Fig. 1 lcrelellces a typical use of such acid, being used in a litdnifef~us ore S bPnPfici~tion process employing a reductive roasting step 15 before the subsequent leach 17.
Hydrochloric acid is the most especially ~l~felled acid employed in the prPli-...n~
le~- hing step of this invention. Other acids such as sulfuric acid, nitric acid, and hydrofluoric acid, while they will soluhili7e the radionuclide values, are generally unrlesir~hle because they attack TiO2 values.
Advantageously the acid cont entr~tion used in the pr~Plimin~ry 1P~h;ng step is about 8 percent or greater by weight, based on the total weight of the solution- More advantageously, the acid will be present in an amount of from about 10 percent to about 30 percent by weight, based on the total weight of the solution. Rec~se a prefellcd embodiment of the invention involves using l~gene-~t~d HCl, preferably, the conc-p-ntration of the acid will be from about 15 percent to about 20 percent based on the total weight of the solution, which is the typical co~ ntration of HCl in regçnP~tçd sollltinn An 18 percent conr~ntration of hydrochloric acid is most plefelled. The product obtained by use of this process contains ci~nifi~ntly reduced r~-lionll~ e conrçntr~tionc Depen~1ing on the s ore involved, the concentratinn HCl employed and the reaction con~itionc~ the process removes greater than about 50 percent of the radionuclides present, preferably above about 75 percent, thereby reducing the r~ionl~ e col~P-ntrationc to generally below 50 ppm.
Ore treated by the process of this invention can thereby be used, without lmdecir~ble health or environmPnt~l effects, in any process in which a benPfi~i~tP~ ti~ .. bearing ore can be 10 used.
Without wishing to be bound to any particular theory, it is believed that the process of this invention derives its utility from the moleclllar structure of the ~ .nill... bearing ore.
A sc~nning electron microscope, using energy dispersive s~;LIusco~y~ has shown spots on the surface of ullLIeated ore particles that contain high cQrlcPntr~tinnc of th~ritlm, u~
and rare earths. This evidence in~lic~t~s that the r~ionu~ litles are hetcrogenevusly distributed on the ore surface and not holllogeneously distributed throughout ore particles.
This is in contr~ct to iron values which are known to be homogeneously distributed within the molecular lafflce of titaniferous ores.
EXAMPLES
Example 1 Commercially available TiWest ilmPnitP ore concçntr~tinnc are given before and after acid lç~hing at 105C and ~I~..o5~hP-ric p~s~ule using 18 percent HCl at 2.7 ml solutinnlg ore, employing two three hour digestions.
2 1 ~538 Impurity Before After TiO2% 64 68 Fe2o3% 31 28 ThO2, ppm 135 38 s U3O8, ppm 10 c5 (Th+U), ppm 127 33 Example 2 Comm~rcially available TiWest ilm~nite ore coi~cç~ ions are given before and after acid l~ching at 140C using 18 percent HCl at 2 7 ml solution/g ore o in ~tmosrh~ri~ p~ l~, employing two three hour reductions Impurity Before After TiO2% 66 68 2 Fe2O3% 31.3 26 9 ThO2, ppm 164 10 U308, ppm c5 c5 (Th+U), ppm 149 9 Example 3 Collll,.~.cially available TiWest ilmenite ore concçntr~tinnc are given before and after acid lp~ching at 160C using 18 percent HCl at 2.7 ml soluti~n/g ore, in ~t~ os~h~; ;c p l s;, -e, employing two three hour reductionc Impurity Before After TiO2% 66 70.1 Fe2o3% 31.3 22 9 ThO2, ppm 164 8 U3O8, ppm c5 c5 (Th+U), ppm 149 7 The fo~egoing is concidered as i~ str~tive only of the prin~ip'~C of the invention Further, since llulll~oUS appli~ ~tionc of the invention, and ml-dific~ti- nc thereof will readily occur to those sl~lled in the art, it is not desired to limit the invention to the exact op~-r~tis~n shown and d~ bed, and accordingly all suitable mo-lific~tion~ and equivalents may be resorted to, falling within the scope of the invention as cl~im~d
Other plucesses are known as ~ltPrn~tives or improvements of the foregoitlg process for the removal of iron and other metallic values from t;l~niln.. bearing ores.
U.S. Patent No. 4,176,159 discloses a process for the removal of impurities from rutile, ilmPnite~ and leucoxene ores. The process lclui.~s high tclllpclalulc c~lcining~
cooling, reducing, cooling, magnetic sep~r~tinn, mineral acid l~P~ching, nP,Utr~ ing~ and washing.
U.S. Patent No. 4,562,048 iicrloses the bPnPfini~ti~m of ~i~,Çe~us ores by lP~ `hillg S with a mineral acid. The telll~ldlulc used is 120-150C, and the plC.~;~lll`C used is 10-45 pounds per square inch gauge ("PSIG"). An e~Pnti~l aspect is the venting of water vapor genPr~ted during the lP~hing process. Prior to lP~ching, the ore is reduced at about 600-1100C.
U.S. Patent No. 4,321,236 discloses a process for bPnPfi~i~ting titaniferous ore. The process ~cyu~s pre-heating the tit~nPf~Prous ore and a mineral acid prior to the lP~Ching oper~tion. The t~n~lx~Atll~c is .~hllil;npd at 110-150C, and the pres~.llc is ...~h.~;.inP~ at 20-50 PSIG. For ores co~ h~ing iron in the ferric state, reductive roasting at about 800-1100 is suggested prior to lP~hing.
U.S. Patent No. 4,019,898 discloses the ~ldition of a small amount of sulfuric acid to the leach liquor used to ben~firi~tr ilmenitç ore. The te~.lpf ,~ ~ used is 100-150C, and the p~ e used is up to 50 PSIG. For ores conl;d~ g iron in the ferric state, the ore is reduced prior to le~çhing at a tcm~cldlulc of about 700-1200C.
s U.S. Patent No. 3,060,002 dicrloses acid lr~rhing of ilm~nite and Sorel slag at lcl~lpcldtule of 150-250C. Prior to l~çhin~, the ore preferably is roasted oxidatively at about 500-1,000C.
U.S. Patent No. 4,038,363 discloses upgrading of tit~nillm values in a slag such as Sorel slag by roasting with an aLkali salt, lr~rhing with sulfuric acid in two stages, and c~lnining.
Japanese Patent No. 48,102,712 discloses dephosph- ri7~tion of !il~n;~.... cc r~nl~i~t~ S
using caustic alkali after prior removal of iron.
Japanese Patent No. 87-33058/47 diccloses production of rutile type ~ n;u~ dioxide solids by heat treating hydldted ~ oxide and alkali metal hydroxide and m~tllring in 5 hydrochloric acid aqueous solution.
These prior art pfocesses do not have as an objective the removal of r~lionllr-lide impurities such as thorium and ~ n;~ and do not teach the removal of r~ionurlidçs These known mçthodc have, in fact, proven in~rre~;~iYe to substantially reduce r~-lionucli-le conr~ntr~ti~nC in t;li.n;l~." bearing ores having cignifi~nt conren~tions of p-lionl~rlides.
20 Since r~dio~cl;vily must be minimi7çd in order to reduce health effects from the use of a ~ n;u... bearing m~tPri~l with radinnllçlide impurities, standard col~ e guid~linpc on radioactivity require synthetic rutile to contain no more than 100 ppm thorium and ...,u.;l~
This is typically accomplichçd by mixing a bPnrfiri~trd ore that is high in thorium and Ul An;~llll with another ore that is low in thorium and uranillm Several l~cel.lly issued patents 2 1 845~i8 have also been directed toward improving r~ nu~lidp removal effiriPnçiPs in lil~n;~
bearing ore benPfici~tinn processes.
U.S. Patent No. 5,181,956 lic~los~Ps a process for removing r~ mlçlid~Ps from tit~ninm bearing ore which comprices reductive roasting followed by a lP~çhing step, which s employs a mineral acid having a concPntration of about 3-30% by weight at a ~I~.pelaLule of about 160-300C, until the desired amount of impurities are soluh~ili7~ and a le~h~tP
is forrned, and then removing the le~h~te from the product of the cont~cting step. The process disclosed by U.S. Patent No. 5,181,956, has the obvious disadvantage of taking place after a reductive roast and under severe con-litionc that can quickly destroy or o degenPratP process equipment.
U.S. Patent Nos. 5,011,666 and 5,085,837 disclose a process for removing radionuclides from ~ ;lllll bearing ore concictin~e escPnti~lly of subjecting the ore to two or more lP~çhing tre~tmp-ntc7 said l~çhing llc~lln~nl~ ~ltPrn~ting beLwæn use of an aqueous solution of a mineral acid and an aqueous solution of an alkaline metal col--~oul d selected 5 from the group consisting eccPnti~lly of alkaline metal ca,bonatcs, hydroxides or Il~i~Lulc5 thereof. The plocesses ~licrlosed by U.S. Patent Nos. 5,011,666 and 5,085,837, do not adequately solve the problem of ra~ n~lçlidP removal because they require too many steps, and much ill~esLm~,lt in and reconfiguration of process e~Luip---ent.
It has been found that if an ore is reduced at high lc~lpcl~t~ s to convert iron oxides 20 to metallic iron, and then the iron is removed from the pores in the ore particles by a non~gressive reaction such as aer~tion in a 0.3 molar solution of ~",...~n;~.... chloridP at ~mbient ~ellll P.~llllle to rust the iron, thorium is not removed from the surface of the ore.
The thorium or other r~ionuçlide ends up in the benPfic i~tP~ ore. Based on these results it would appear that a more aggressive reaction would be needed to erre~lively remove the 2i8~
r~dionucli~e impurities. Indeed, U.S. Patent No. 5,181,596 discloses just such a method, by dicclo~in~ a process of a reductive roast followed by an acid lP~hing process at an elevated l~ pf ~ e belw~ll 160C and 300C to errec~ively remove the r~rlinnuc1i~e impurities and to produce a s~lfficiently pure bPnefi~i~te~ ore.
SUMMARY OF THE INVENTION
It has been unexpectedly found, however, that the efficiency of ra-lionuçli~e removal in a li~niulll bearing m~ten~l benification process can be s,lls~lliaUy h~lyluved by subjecting the ~ nill.ll bearing m~tPri~l to a prelimin~ry l~chin~ step, prior to reductive roasting, under mild conditions in a mineral acid bath, sep~r~ting the mineral acid from the ore, and thereafter prDce~sing the ore according to any benifiç~tio n process known to reduce the impurities ren ~ining in the ~ i"ln bearing m~te i~l According to this invention, there is provided a process for purifying ti~ ,lll ore and removing r~ nu~lide impurities therefrom, comrri~ing~ prior to reductive roasting, lP~ching the ore adv~l~geollsly at ,no5~,hP ic p~lS~ and at a tel-lpel~lule range from about 100C to about 110C, preferably at about 105C in a mineral acid bath, of optimally 18 percent hydrochloric acid by weight, thereby solllbili7ing the ra~ionucli-le values in the ore; s~ ling the mineral acid solution and solubilized r~-lionucli-lPe impurities from the ore; and further pl~)ces~ing the ore according to benPfic~tion p~ocesses known to remove rt-"~ining impurities such as iron.
In accordallce with this invention, it has been found that the aforem-ontioned radio~lu~ P impurities can be readily reduced to an acceptable level, especi~lly when producing tit~nillm dioxide by the chlorid~ process. It also has been found that (1) relative to commercially available acids, dilute acids often can be used for the ore pre~ -hing step which are less èxpensive and produce less amounts of waste streams than strong acids; and (2) mineral acid used in the ore prPlP~(hing step can be bPnefiri~lly reused as the acid in a subsequent acid lF~ching step if called for by the benFfici~ting process ~ ~' ",ed, which reduces the problem of disposing or legenF, 1;ng such acids. Finally, the process of this invention is highly useful and desirable because it will make pra-ti~l the utili7~tion of low-grade, inF pPn~;ve and more abundant ~ ;ulll dioxide ore which cQ~ nc r~-iionuçli~e s impurities. The process is also simple and requires few steps.
DESCRIPIION OF THE DRAWING
Fig. 1 depicts a treatment process employing the subject invention in a typical titaniferous benPfit~i~tion process.
DETAILED DESCRIPTION OF lH~; PREFERRED EMBODIMENT
The process of this invention can be practiced on any tit~nium bearing m~teri~l in any form, in~ ding anatase, ilmFnite and rutile. Preferred m~tPri~l~ are li~ifeluus, such as ilmPnite, titaniferous hem~tite, and titaniferous m~g1l~PtitP~ F~pPri~lly prerelr~d is ilmenitç. Re~ e radion~ e impurities are most commonly ~o~i~tPd with ~ elv~ls ores such as ilmPnite, leuco~rPnP, rutile, perovskite, and sphene, the process can advantageously be applied to reduce ra-lionu~lide levels in these ores. As used herein, the term "ore" in~lud~ps raw ore and benPfi~i~tes and d~iv~ s thereof such as slag, blowover fines from lit~nh~" dioxide rhlo.;,-~t~ , or other process streams from a l;~nill", dioxide m~nufaçtl-ring process. The terms l;l;tn;~llll dioxide ore, I;l~n;lllll bearing ore, and l;l~n;
bearing m~teri~l, are all used inlerchallgeably.
An ore from western Al~strali~ known col,llllercially as TiWest ore is a typical l;l;,n;lJ-" bearing ore that can be pr~is~d ben~fi~ lly according to this invention. Such ore has the disadvantage of having a high concpntr~tion of thorium -- ranging from about 120 to about 170 ppm by weight. Thorium distributes itself bt;lwæn the synthetic rutile and iron oxide products from the synthetic rutile process. Such ore normally con~ c less than about 10 ppm 1l~
Though the process of this invention is generally ~rr~;~ive to remove ra~ nl-çli~içs from all sizes of ore, the present invention is particularly err~;~ive for plvcesaing ores havin s a particle size of from about 200 to about 20 mesh.
The impurities which can be removed in accordance with the process of this invention include but are not limited to radionuç~ Ps such as thorium and UldlliUlll. The process of this invention can be employed singularly to remove only the r~-lionu~ P i,lll)ulities from the base m~tPri~l, or can be pelrol",ed in conjunction with known benPfi~i~tion plucesses to remove other i~pulilies, such as, for e~mple, iron, pho~holus, ~11l-.. ;--l~- ., m~n~n~se, c~lcil~m) barium, sl,o"liu"" chr~""iu"" v~n~ -m, yttrium, and l~nth~ni~P e1~m~ntC such as l~n~ nll.", cerium, and neody,l,iu"l. FY~mrlçs of benPfiçi~tion pn~cesses to remove these elem~Pnt~ are identifi~d in the background section of this spPcifiç~tion~
The invention compri~es l~çhing the ~ ,;ll.., bearing m~tPri~l in a mineral acid leach 5 prior to reductive roasting. Preferably the acid leach is pelroll"ed as the first step of a known bemPfi~ tit n process. A co,~ ing~ sizing, or ~rin-ling process may be employed before the acid leach, to obtain the most erreclively sized and shaped ore particles. Fig. 1 shows the initial step to remove the r~diomlcli~e impurities from a ~ ;l,.., bearing ore stream 11 taking place in step 12 before any roasting or le~hing of the m~tPri~l to remove 20 other impurities in the ore as in steps 15 and 17.
The inventive le~hing step 12 takes place at a te",p~ldt~ie and pl~sau~e, and for a time, which is suMt~ient to solubilize a~a~ultially the radi(nllçli~e impurities present.
Ordinarily, the time le~luilt;d will be at least about 1 hour. Typical ranges of time are from about 1 hour to about 6 hours, p~Çeldbly from about 3 hours to about 6 hours, and most - 2 1 8~8 pl~eÇcldbly about 5 hours to about 6 hours. The lclllp~l~lulc will advantageously be from about 100 to less than about 160C, preferably from about 100 to about 110C, and most preferably at about 105C, the boiling point of 18 percent hyd~ucllloric acid at ~tmosphPric pfes~.~rc. Although trç~tmPnt~ at lclllpeldlul~s greater than 160C have also proven err~clive s to remove r~diomlçlides, operation of process equipment at greater than 160C leads to rapid equipment dege~ ir,n The pre~ -y lr~çhing step 12 can be pclÇoll~ed at about ~tmnSph~Prir plCS~UlC.
~d-lition~l pre~nri7~tirn can be added, if desired. Preferably, the ples~.-rc range will be from about 1 to about 5 atmospheres absolute, and most preferably at at~llo~llclic p~cs~..re.
10 The le~çhing can be pe,ro,llled in one or more digestions, based on the desired rate of removal of r~ionuçli~e impurities, and the desired end c~nr-ontr~ti-n of r~-lion~ e impurities in the ore.
It has been found that the lcll-pcl~ure and pres~urc of the process step 12 should preferably be ...~in~i.inPA at about the boiling point of the leach liquor. It is believed that boiling the leach ensures mixing of the ore and leach, and f~rilit~t~s in~ .rlisn and reaction between the acid and r~ionllrlide colllpollel-t~. Operation of the in~,enlivc le~ching step at the mineral acid boiling point adds the further advantage that the te~ C iS ill!~llffiri~P.nt to attack the lit:~nilllll portion of the ore to any ~ ultive extent. In this manner the ore is best plcs~lvcd for more effective p,ocessing by, for eY~mple, a succe~ive reductive roasting and lP~rhing process to remove fe~ ining impurities as shown in Figure 1, steps 15 and 17.
Operation of the ill~.,ltiVC le~hing step at the mineral acid boiling point also has the advantage that it does not induce the ~ignific~ntly harsh conrlition~ that can cl~PtPril~ratP
process e luiylllent.
2 1 8453~
It has also been found that by sepaldling the radiomlçlide col-lponenls from the ore before further agg.~ssive trP~tmPnt~ such as reductive roasting, the r~dionllç1idPs are more effectively and completely removed from the tit~nium bearing m~tPri~l The lP~`h~tP can be removed by any suitable means, incl~l~ing filtrating, dec~nting, centrifuging, or use of a s hydroclone or c~ ifiPr. DepPn~ing on the process employed, wash water or very dilute HCl solution can be used to wash the ore.
A substantial benefit can be realized from this invention by reusing th~e acid sollltil~n sep~dted from the ore in the initial lP~hing step, as illustr~tP~d by Stream 14 in Figure 1.
Reca~lse very little of the ore other than the radionuçlide content is ~tt~Ç~P~ at the mndPr~tP
10 telll~ldlure and pres~u~e employed in the initial lP~ehing step the acid removed from the initial leach should be nearly the same concentration as when it was originally introduced to the kP~hing step, without having gone through extensive regeneration tre~tmPnt This acid solution may, therefore, be introduced into a subsequent lP~hing step without any proce~ing. Fig. 1 lcrelellces a typical use of such acid, being used in a litdnifef~us ore S bPnPfici~tion process employing a reductive roasting step 15 before the subsequent leach 17.
Hydrochloric acid is the most especially ~l~felled acid employed in the prPli-...n~
le~- hing step of this invention. Other acids such as sulfuric acid, nitric acid, and hydrofluoric acid, while they will soluhili7e the radionuclide values, are generally unrlesir~hle because they attack TiO2 values.
Advantageously the acid cont entr~tion used in the pr~Plimin~ry 1P~h;ng step is about 8 percent or greater by weight, based on the total weight of the solution- More advantageously, the acid will be present in an amount of from about 10 percent to about 30 percent by weight, based on the total weight of the solution. Rec~se a prefellcd embodiment of the invention involves using l~gene-~t~d HCl, preferably, the conc-p-ntration of the acid will be from about 15 percent to about 20 percent based on the total weight of the solution, which is the typical co~ ntration of HCl in regçnP~tçd sollltinn An 18 percent conr~ntration of hydrochloric acid is most plefelled. The product obtained by use of this process contains ci~nifi~ntly reduced r~-lionll~ e conrçntr~tionc Depen~1ing on the s ore involved, the concentratinn HCl employed and the reaction con~itionc~ the process removes greater than about 50 percent of the radionuclides present, preferably above about 75 percent, thereby reducing the r~ionl~ e col~P-ntrationc to generally below 50 ppm.
Ore treated by the process of this invention can thereby be used, without lmdecir~ble health or environmPnt~l effects, in any process in which a benPfi~i~tP~ ti~ .. bearing ore can be 10 used.
Without wishing to be bound to any particular theory, it is believed that the process of this invention derives its utility from the moleclllar structure of the ~ .nill... bearing ore.
A sc~nning electron microscope, using energy dispersive s~;LIusco~y~ has shown spots on the surface of ullLIeated ore particles that contain high cQrlcPntr~tinnc of th~ritlm, u~
and rare earths. This evidence in~lic~t~s that the r~ionu~ litles are hetcrogenevusly distributed on the ore surface and not holllogeneously distributed throughout ore particles.
This is in contr~ct to iron values which are known to be homogeneously distributed within the molecular lafflce of titaniferous ores.
EXAMPLES
Example 1 Commercially available TiWest ilmPnitP ore concçntr~tinnc are given before and after acid lç~hing at 105C and ~I~..o5~hP-ric p~s~ule using 18 percent HCl at 2.7 ml solutinnlg ore, employing two three hour digestions.
2 1 ~538 Impurity Before After TiO2% 64 68 Fe2o3% 31 28 ThO2, ppm 135 38 s U3O8, ppm 10 c5 (Th+U), ppm 127 33 Example 2 Comm~rcially available TiWest ilm~nite ore coi~cç~ ions are given before and after acid l~ching at 140C using 18 percent HCl at 2 7 ml solution/g ore o in ~tmosrh~ri~ p~ l~, employing two three hour reductions Impurity Before After TiO2% 66 68 2 Fe2O3% 31.3 26 9 ThO2, ppm 164 10 U308, ppm c5 c5 (Th+U), ppm 149 9 Example 3 Collll,.~.cially available TiWest ilmenite ore concçntr~tinnc are given before and after acid lp~ching at 160C using 18 percent HCl at 2.7 ml soluti~n/g ore, in ~t~ os~h~; ;c p l s;, -e, employing two three hour reductionc Impurity Before After TiO2% 66 70.1 Fe2o3% 31.3 22 9 ThO2, ppm 164 8 U3O8, ppm c5 c5 (Th+U), ppm 149 7 The fo~egoing is concidered as i~ str~tive only of the prin~ip'~C of the invention Further, since llulll~oUS appli~ ~tionc of the invention, and ml-dific~ti- nc thereof will readily occur to those sl~lled in the art, it is not desired to limit the invention to the exact op~-r~tis~n shown and d~ bed, and accordingly all suitable mo-lific~tion~ and equivalents may be resorted to, falling within the scope of the invention as cl~im~d
Claims (19)
1. An improved process for beneficiating a titanium bearing material which comprises the steps of reductively roasting the titanium bearing material followed by leaching in a mineral acid leach, wherein the improvement comprises subjecting the titanium bearing material to a heat treatment in an aqueous solution of a mineral acid to remove radionuclide impurities before reductive roasting.
2. A process as in claim 1, wherein the titanium bearing material is ilmenite, leucoxene, high grade titanium ore, titanium slag, or synthetic rutile.
3. A process as in claim 1, wherein the titanium bearing material is titaniferous.
4. A process as in claim 1, wherein the titanium bearing material has a particle size of about 200 US mesh or larger.
5. A process as in claim 4, wherein the titanium bearing material has a particle size of from about 200 to about about 20 US mesh.
6. A process as in claim 1, wherein the treatment time is at least about 1 hour.
7. A process as in claim 6, wherein the treatment time is from about 3 to about 6 hours.
8. A process as in claim 1, wherein the mineral acid is hydrochloric acid.
9. A process as in claim 1, wherein the concentration of the mineral acid is from about 8 percent to about 30 percent by weight.
10. A process as in claim 9, wherein the concentration of the mineral acid is from about 15 percent to about 20 percent by weight.
11. A process as in claim 8, wherein the concentration of the hydrochloric acid is about 18 percent by weight.
12. A process as in claim 1, wherein the heat treatment is carried out at a pressure between about one atmosphere and about five atmosphere.
13. A process as in claim 12, wherein the heat treatment is carried out at about atmospheric pressure.
14. A process as in claim 1, wherein the heat treatment is carried out at from about 100°C to less than about 160°C.
15. A process as in claim 1, wherein the heat treatment is carried out at from about 100°C to about 110°C.
16. A process as in claim 1, wherein the heat treatment is carried out at about 105°C.
17. A process as in claim 1, wherein the concentration of radionuclides is reduced by about 50 percent or more prior to reductive roasting.
18. A process as in claim 1 wherein the titanium bearing ore is titaniferous, the mineral acid is separated from the titanium bearing material after the radionuclides impurity removal treatment, followed by reductive roasting of the titanium bearing material, and subsequent leach of the titanium bearing material using the mineral acid previously separated from the titanium bearing material.
19. An improved process for beneficiating a titanium bearing material containing from about 120 to about 180 ppm combined thorium and uranium which comprises the steps of reductively roasting the titanium bearing material, followed by leaching in a mineral acid leach, wherein the improvement comprises subjecting the titanium bearing material to a heat treatment in an aqueous solution of a mineral acid to remove radionuclide impurities prior to reductive roasting.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US53441695A | 1995-09-27 | 1995-09-27 | |
| US08/534,416 | 1995-09-27 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2184538A1 true CA2184538A1 (en) | 1997-03-28 |
Family
ID=24129934
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002184538A Abandoned CA2184538A1 (en) | 1995-09-27 | 1996-08-30 | Removal of radionuclides from titanium bearing ores |
Country Status (8)
| Country | Link |
|---|---|
| EP (1) | EP0765943A1 (en) |
| JP (1) | JPH09124318A (en) |
| KR (1) | KR970015772A (en) |
| AU (1) | AU6055596A (en) |
| BR (1) | BR9603638A (en) |
| CA (1) | CA2184538A1 (en) |
| EA (1) | EA199600072A3 (en) |
| SG (1) | SG77119A1 (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5997606A (en) * | 1997-08-11 | 1999-12-07 | Billiton Sa Limited | Production of titanium slag |
| BR0304443B1 (en) * | 2003-10-28 | 2012-08-21 | process for obtaining high thio2 and low radionuclide titanium concentrates from mechanical anatase concentrates. | |
| CN101935063B (en) * | 2009-09-02 | 2012-01-25 | 沙立林 | High titanium hydrochloric acid leaching slag and application thereof |
Family Cites Families (15)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US1902203A (en) * | 1931-01-21 | 1933-03-21 | Bichowsky Foord Von | Process of preparing titanium dioxide |
| US2127247A (en) * | 1935-06-15 | 1938-08-16 | Du Pont | Preparation of compounds of titanium |
| US2903341A (en) * | 1956-12-24 | 1959-09-08 | Kenneth B Ray | Process of treating ferrotitaniferous materials |
| US3060002A (en) * | 1959-09-25 | 1962-10-23 | Dow Chemical Co | Pressure leaching of titaniferous material |
| US3457037A (en) * | 1967-08-15 | 1969-07-22 | Nat Lead Co | Method for producing titanium dioxide concentrate from massive ilmenite ores |
| JPS48102712A (en) * | 1972-04-11 | 1973-12-24 | ||
| US4038363A (en) * | 1975-10-21 | 1977-07-26 | Quebec Iron & Titanium Corporation-Fer Et Titane Due Quebec, Inc. | Upgrading sorelslag for production of synthetic rutile |
| US4019898A (en) * | 1976-04-30 | 1977-04-26 | Benilite Corporation Of America | Beneficiation of ilmenite ore |
| US4176159A (en) * | 1976-11-15 | 1979-11-27 | Mendonca Paulo Ayres Falcao De | Process for concentration of titanium containing anatase ore |
| US4321236A (en) * | 1981-02-05 | 1982-03-23 | Kerr-Mcgee Chemical Corporation | Process for beneficiating titaniferous materials |
| US4562048A (en) * | 1984-04-30 | 1985-12-31 | Kerr-Mcgee Chemical Corporation | Process for the treatment of metal-bearing ores |
| US5011666A (en) * | 1988-07-28 | 1991-04-30 | E. I. Du Pont De Nemours And Company | Method for purifying TiO2 ore |
| US5085837A (en) * | 1988-07-28 | 1992-02-04 | E. I. Du Pont De Nemours And Company | Method for purifying TiO2 ore by alternate leaching with an aqueous solution of an alkali metal compound and an aqueous solution of mineral acid |
| US5181956A (en) * | 1990-03-08 | 1993-01-26 | E. I. Du Pont De Nemours And Company | Method for purifying TiO2 ore |
| JPH0688149A (en) * | 1992-09-08 | 1994-03-29 | Ishihara Sangyo Kaisha Ltd | Method for refining titanium-containing material |
-
1996
- 1996-07-18 AU AU60555/96A patent/AU6055596A/en not_active Abandoned
- 1996-08-16 EP EP96305991A patent/EP0765943A1/en not_active Withdrawn
- 1996-08-22 SG SG1996010517A patent/SG77119A1/en unknown
- 1996-08-22 KR KR1019960034819A patent/KR970015772A/en not_active Application Discontinuation
- 1996-08-30 CA CA002184538A patent/CA2184538A1/en not_active Abandoned
- 1996-09-03 BR BR9603638A patent/BR9603638A/en not_active Application Discontinuation
- 1996-09-26 EA EA199600072A patent/EA199600072A3/en unknown
- 1996-09-27 JP JP8255839A patent/JPH09124318A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| JPH09124318A (en) | 1997-05-13 |
| AU6055596A (en) | 1997-04-10 |
| BR9603638A (en) | 1998-05-19 |
| EA199600072A2 (en) | 1997-03-31 |
| KR970015772A (en) | 1997-04-28 |
| SG77119A1 (en) | 2000-12-19 |
| EP0765943A1 (en) | 1997-04-02 |
| EA199600072A3 (en) | 1997-06-30 |
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