AU639390B2 - Removal of radionuclides from titaniferous material - Google Patents

Description

639390 Regulation 3.2

AUSTRALIA

Patents Act 1952 COMPLETE SPECIFICATION FOR A STANDARD PATENT

(ORIGINAL)

Name of Applicant: Actual Inventor(s): 1C Sads AMC-MINERAL SANDS ELB

(SEB

Martin Richard HOUCHIN Halil ARAL ir Warren John BRUCKARD David Edward FREEMAN Harold Robert HARRIS Ian Edward GREY DAVIES COLLISON CAVE, Patent Attorneys, 1 Little Collins Street, Melbourne, 3000.

REMOVAL OF RADIONUCLIDES FROM TITANIFEROUS MATERIAL Address for Service: Invention 'itle: Details of Associated Provisional Application(s): No(s): PK5708/91 The following statement is a full description of this invention, including the best method of performing it known to me/us: -1- -la- REMOVAL OF RADIONUCLIDES FROM TITANIFEROUS MATERIAL This invention relates to a process for facilitating the removal of radionuclides from titaniferous materials, and is particularly concerned with the removal of radionuclides such as thorium and/or uranium from weathered or "altered" ilmenite.

Ilmenite (FeTiO 3 and rutile (TiO 2 are the major, commercially-important, mineral feedstocks for titanium metal and titanium dioxide production. Although ilmenite and rutile almost invariably occur together in nature as components of "mineral sands" or "heavy minerals" (along with zircon (ZrSiO 4 and monazite La, Th)PO 4 ilmenite is usually the most abundant. Natural weathering of ilmenite results in partial oxidation of the iron, originally present in ilmenite in the ferrous state (Fe 2 to ferric iron To maintain electrical neutrality, some of the oxidised iron must be removed from the ilmenite lattice. This results ir, a more porous structure with a higher titanium (lower iron) content. Such 20 weathered materials are known as "altered" ilmenites and may have TiO 2 cbntents in excess of 60% TiO 2 compared with 52.7% TiO 2 in stoichiometric (unaltered) ilmenite. As weathering, or alteration, of the ilmenite proceeds, impurities such as alumina-silicates (clays) are often incorporated into the porous structure as discrete, small grains that reside in the pores of the altered ilmenite. It appears that radionuclides such as thorium and/or uranium can also be incorporated into the ilmenite during this process.

Most of the world's mined ilmenite is used ior the production of titanium dioxide for use in the paint pigment industry. Pigment-grade titania (titanium dioxide, TiO2) has been traditionally produced by reacting ilmenite with concentrated sulphuric acid, with subsequent hydrolysis of the titanium sulphate to titania the so-called sulphate route. However this process is becoming 920410,gjnspe.007,AMC,C2,1 -2increasingly unpopular due to environmental considerations. The chloride route, which involves reaction with chlorine to produce volatile TiC1 4 which in turn is converted to TiO 2 presents fewer environmental problems and is currently the preferred method for pigment-grade titania production. However rutile or "synthetic rutile" (rather than ilmenite) are the preferred feedstocks for the chloride route because the large amount of iron in ilmenite causes excessive consumption of chlorine during processing. Hence an increasing amount of the world's production of ilmenite is being converted to synthetic rutile (TiO 2 content 90%) for use in the chloride-route, pigment-production process. A number of different processes have been developed to upgrade ilmenite to synthetic rutile, the most widely used, commercially, being the Becher process.

The Becher process involves reducing the iron in ilmenite (preferably altered ilmenite) to metallic iron in a reduction kiln at high temperature, then oxidising the metallic iron in an aerator to produce a fine iron oxide that can be physically separated from the coarse titanium-rich grains. The product finally undergoes a dilute acid leach. The titanium-rich synthetic rutile so produced contains typically >92% TiO 2 Whether ilmenite is marketed as the raw mineral or as upgraded, valueadded synthetic rutile, producers are being increasingly required to meet more 20 stringent guide-lines for the levels of radionuclides, e.g. thorium and uranium, in their products. The Becher synthetic rutile process does not reduce the levels of radionuclides in the product and so there exists an increasing need to develop a commercially satisfactory process for removal of radionuclides from ilmenite and/or from other titaniferous material such as synthetic rutile. Provision of such a process is therefore an object of the invention.

A difficulty in determining an appropriate method for the removal of radionuclides from titaniferous material is that it is not known just how the radion iclides are present in the mineral. It is known, for example, to dissolve pure ThO2 in acid U.S. Atomic Energy Comm. TID-5223, 107-17] but experimental acid leaches of ilmenite for the present applicant have achieved only limited removal of radionuclides such as thorium and uranium from the ilmenite.

920414,gjnsp.007,AMC.C2,2 -3- The thorium may not be present as ThO 2 or, even if ThO 2 may not be in a readily dissolvable form.

US patent 5011666 discloses a process for purifying TiO 2 ore, by reducing the levels of a number of impurities including thorium and uranium. The process entails subjecting the ore to two or more leaching treatments including the use of an aqueous solution of a mineral acid and an aqueous solution of an alkali metal compound selected from the group consisting of alkali metal carbonates, hydroxides and mixtures thereof. According to the claims of the reference, the acid leach is effected first but the reference also discloses an effective treatment in which an alkali metal leach under severe conditions (25% NaOH at 18 atm and 210 is followed by the acid leach.

While the multiple leach process proposed in US patent 5011666 may per se effectively reduce thorium and uranium content, the leaching conditions discussed are generally very severe and are intended to extract a varicty of impurities, and iron in particular, from the titaniferous material. The process is particular to anatase and if it were applied as disclosed to primary ilmenite, there would be loss of titanium values by reaction with the acid and/or by acid dissolution of alkali metal titanates formed during the strong alkali leach.

Moreover, the levels of acid and alkali reagents required, and other process 20 conditions specified in the patents, render the process uneconomic for the purposes of the present exercise.

It has also been proposed, in Australian patent 599090, to removal various impurities including thorium and uranium by roasting TiO 2 ore with an alkali metal compound to convert the thorium and uranium for subsequent leaching with a non-sulphuric mineral acid. The TiO 2 ore is preferably anatase but may be ilmenite. This process, which is ciposely related to a general processing system disclosed, eg, in US patent 4759916, is complex and expensive.

It has been realised that thorium and uranium removal can surprisingly still be achieved at effective levels under leaching conditions which are much milder than those disclosed in US patent 5011666, but at which both iron and titanium values are substantially preserved and the process is more economically and 920415,gjnspe.007,AMC.C2,3 -4practicably viable. More generally, it has been appreciated that removal of radionuclides from titaniferous material by acid leaching is greatly enhanced if the material is first treated in a manner to alter the state of the radionuclides in the material for a more effective subsequent acid leach, and that one such treatment is treatment of the titaniferous material with a base under conditions such that iron and titanium are substantially not dissolved from the titaniferous material.

According to the present invention, there is therefore provided a process for facilitating removal of radionuclides from titaniferous material which comprises the steps of subjecting said titaniferous material to a treatment in a manner to alter the state or condition of radionuclides in the material for a more effective subsequent acid leach, and thereafter leaching the titaniferous material with acid to dissolve radionuclides, wherein the conditions of such treatment and said leach are such that titanium and iron are substantially not dissolved from the S. :material.

15 By "substantially not dissolved" is meant herein that less than 10% is dissolved, preferably less than most preferably less than 2%.

The process preferably includes the further step of separating the radionuclides from the titaniferous material. Such separation can be effected by any suitable known method, eg filtration or cyclone separation.

The base may, eg be an alkali metal or alkaline earth compound, eg oxide, hydroxide or carbonate, or ammonia. However, a preferred said treatment is contact with an aqueous basic solution, most preferably an aqueous solution ot a strong base eg an alkali metal oxide or hydroxide, under conditions effective :to achieve said alteration of the state or condition of the radionuclides but such that iron and titanium are substantially not dissolved from said material. By "strong" base, is meant herein a base substantially fully dissociated in water.

The term "state or condition of radionuclides" may refer herein to their chemical state, e.g. the compounds in which the radionuclides are primarily present, and/or to the physical state or condition. An example of the physical state or condition is the structure or phase in which the radionuclides are found in the titaniferous material. By way of particular example, in altered ilmenite, 920415,gjnspe.07,AMC.C2,4 alumino-silicates may restrict access to the thorium or other radionuclide traces and thus the acid leach may be rendered more effective by pre-treating the ilmenite to alter the condition of the thorium by partially or wholly removing the alumino-silicates and thereby enhancing access to the radionuclide traces during the subsequent acid leach.

Pre rably, the titaniferous material is ilmenite, altered ilmenite, reduced ilmenite or synthetic rutile. The radionuclides removed preferably include at least thorium and/or uranium radionuclides.

The alkali hydroxide may be caustic soda, (sodium hydroxide) or caustic potash (potassium hydroxide), but caustic soda is especially preferred, eg for economic and handling reasons. Similarly any suitable acid can be used for the acid leach, for example sulphuric, hydrochloric or nitric acid. A mineral acid is however generally preferred, and sulphuric acid is especially preferred, eg for economic and handling reasons.

It will be appreciated that the conditions used for the process of the present invention, for example the temperature, reagent concentration, and the time required for each step, will depend upon the degree of radionuclide removal required, on the nature of the titaniferous starting material used, on the particular radionuclide present, and on the original levels of the radionuclide(s). An appropriate set of conditions mnay also depend upon external factors such as economic and other practical considerations. In general, a greater degree of removal of radionuclides such as thorium and uranium can be achieved by using higher temperatures, high reagent concentrations and longer leaching times.

The process is preferably carried out at or close to atmospheric pressure.

The acid concentration and temperature that can be used in the acid leach are limited by the propensity of the titaniferous feed material to react with the acid, thereby resulting in loss of titanium value. For example, ilmenite has a greater propensity to react with acid than does synthetic rutile. In general, process conditions in the acid leach step are preferably chosen so as to minimise or eliminate loss of titanium value through reaction of titanium with the acid.

Preferably, the treatment step is performed with a caustic solution of 920415,gjnspe.007,AMC.C2,5 -6concentration no greater than about 15 molar, and preferably greater than 0.1 molar. A useful commercially available solution is 12.5 molar. The maximum preferred caustic concentration may be to some extent temperature dependant.

The temperature of the basic solution is preferably maintained above 50 °C but not greater than 125 0 C, but the process may be carried out over any extended period at ambient temperatures, eg by heap leaching. The treatment with a basic reagent is preferably followed by a washing step prior to the acid-leaching step.

The maximum acid concentration if loss of titanium value is to be avoided or at least minimised will depend on the temperature and on the actual titaniferous material used. The higher the temperature, the lower the maximum acid concentration. Primary ilmenite is more reactive than altered ilmenite which is more reactive in turn than anatase, rutile and synthetic rutile and thus the maximum acid concentration will be lower for altered ilmenite than for synthetic rutile. A satisfactory combination of conditions for altered ilmenite is 3 molar 15 sulphuric acid concentration at 90 but it is believed that the acid concentration "at 90°C may be as high as 10 molar. A practical limit, set by general consideration of acid handling such as corrosion levels and recovery requirements, is 10 molar. It is also thought that the maximum acid concentration may vary according to the acid employed, eg higher for sulphuric than hydrochloric.

During the acid-leaching step the acid leach solution is preferably maintained above 50 °C but not greater than 125 The acid concentration is preferably greater than 0.1 molar.

In practice, the upper limits for reagent concentrations and temperatures are usually determined by economic considerations, but it appears that no substantial additional benefit is gained for concentrations greater than 10 molar and temperatures greater than 125 The time elapsed for the respective treatments is preferably at least 10 mins for the treatment with the base and hour for the acid leach. A practical upper limit for each treatment is about 4 or hours, preferably h to 2 hours.

The process of the present invention can be performed at various solids concentrations on a batch or continuous basis. For example, at concentrations no 920415,gjnspc.007AMC.C2,6 -7greater than approximately 75% w/w solids, the process can be performed on a stirred suspension in a heated reactor. At higher solid contents the process can be performed on an appropriately wetted solid in saggers in an oven, or in a rotary kiln.

It has been further found that treatment of titaniferous material with a base followed by an acid leach has the further benefit of removing base-soluble and acid-soluble impurities from the feed material, resulting in a product with a higher titanium content. For example, the A1 2 0 3 and SiO 2 contents can be substantially reduced in the product of the process according to the invention.

It will be appreciated that the degree of removal of base-soluble and acid-soluble impurities (and hence the increase in the titanium content of the product of the present invention) will also depend on severity of the conditions used.

It has been further found that the efficiency of the process of the present invention can be further enhanced if the acid leach is carried out in the presence S 15 of added fluoride, for example in accordance with a copending patent application concurrently filed herewith also entitled "Removal of Radionuclides from Titaniferou Material". The added fluoride is present in an amount effective to further enhance dissolution of the altered radionuclides but substantially without dissolving titanium from the titaniferous material. The fluoride concentration is S 20 preferably in the range 0.01 to 2.0 molar, most preferably in the range 0.05 to molar. Any suitable additive can be used as the source of the added fluoride, for example hydrofluoric acid (unless this is the acid employed for the acid leach), b.

sodium fluoride, ammonium fluoride, or sodium fluorosilicate.

oe Frequently ilmenite concentrates contain low levels of thorium due to monazite contamination. It is thought that the process of the invention does not remove macroscopic monazite grains from titaniferous materials, but rather removes microscopic radionuclide traces originally incorporated into the ilmenite grains during the weathering process.

920414,gjnspe.007,AMC.C2,7 EXAMPLE 1 100 g of ilmenite (from Eneabba North, Western Australia) was reacted with 150 cm 3 of 10 molar sodium hydroxide solution in a reactor fitted with a stirrer rotating continuously at 750 rev/min., a thermopocket containing a thermometer (or thermocouple) and a reflux condenser. The reactor was heated by a heating mantle that was connected via a temperature controller to the thermocouple. In this way, the reaction mixture could be maintained at the desired temperature. The mixture was heated at 115 0 C for 4 hr. The solid residue was then filtered, thoroughly washed with water and analysed. (This material is subsequently referred to as "caustic-treated product").

The caustic-treated product was then returned to the reactor and leached with 300 cm 3 of 1 molar sulphuric acid solution at 85 0 C for 2 hr. The solid residue was again filtered, washed thoroughly with water, dried and analysed. (This product is subsequently referred to as "caustic and acid-leached product").

S.The XRF analyses for the ilmenite feed material, the caustic-treated product and the Scaustic and acid-leached product are given in Table 1.

TABLE 1 XRF Analysis Ilmenite feed Caustic treated Caustic and acid (Eneabba North) product leached product TiO 2 59.99 60.52 61.31 Fe 2 0 3 (total Fe) 34,12 34.50 34.62 ThO 2 0.051 0.049 0.012 SiO 2 1.00 0.20 0.18 A1 2 0 3 0.64 0.32 0.26 EXAMPLE 2 9 To demonstrate the effect of not preceeding the acid leach with a caustic treatment.

No caustic leach was performed on the ilmenite, The acid leach was performed as described in Example 1. (This product is subsequently referred to as "acid-leached product").

TABLE 2 XRF Analysis Ilmenite feed Acid leached (Eneabba North) product TiO 2 59.99 60.01 Fe 2 03 (total Fe) 34.12 34.20 ThO 2 0.051 0.042 SiO 2 1.00 0.89 A1 2 0 3 0.64 0.49 *4 4 4 EXAMPLE 3 -10 To demonstrate the effect of the concentration used in the caustic treatment.

These experiments were performed as described in Example 1 except that a) the caustic leach was performed using various concentrations at 75 0 C for 30 mins b) the acid leach was performed using 5 molar H 2

SO

4 at 87 0 C for 2 hr TABLE 3 XRF Ilmenite feed Concentration of NaOH Analyses (Eneabba North) 0.5M l.OM 2.0M 4.0M TiO 2 59.99 61.09 61.35 62.20 62.64 61.53 Fe 2 0 3 (total Fe) 34.12 34.15 34.04 34.47 34.46 35.29 ThO 2 0.051 0.018 0.016 0.016 0.012 0.008 SiO 2 1.00 0.69 0.64 0.51 0,50 0.45 A1 2 0 3 0.64 0.40 0.39 0.37 0.30 0.31 eee *e e o eoee oo EXAMPLE4 To demonstrate the effect of the temperature used in the caustic treatment.

These experiments were performed as described in Example 1 except that a) the caustic leach was performed using 1.OM NaOH at various temperatures for mm b) the acid leach was performed using 5 molar H 2 S0 4 at 87 0 C for 2 hr TABLE 4 XRF Ilmenite feed Temperature of capd leach Analyses (Eneabba North) 50 0 C 75 0 C 100 0

C

TiO 2 59.99 60.90 62.15 61.97 Fe 2 0 3 (total Fe) 34.12 34.33 34.31 34.19 ThO 2 0.051 0.031 0.020 0.018 SiO 2 1.00 0.82 0.61 0.60 A1203 0.64 0.47 0.42 0.33 s* e r i 12 EXAMPLE To demonstrate the effect of the concentration used in the acid leach These experiments were performed as described in Example 1 except that a) the caustic leach was performed using 4.0M NaOH at 75 0 C for 1 hr b) the acid leach was performed using various concentrations of H 2 S0 4 at 87 0 C for 2 hr TABLE XRF Ilmonite feed Concentration of 1HSO 4 Analyses (Eneabba North) 1.0M 2.5M TiO 2 59.99 62.88 62.41 63.09 Fe 2 0 3 (total Fe) 34.12 35.11 35.07 35.03 ThO 2 0.051 0.022 0.018 0.012 SiO 2 1.00 0.35 0.34 0.45 A1 2 0 3 0.64 0.35 0.38 0.34 *1 a *l o* o ,e *eoe EXAMPLE 6 13 To demonstrate the effect of the time used in the caustic leach These experiments were performed as described in Example 1 except that a) the caustic leach was performed using 1.OM NaOH at 75 0 C for various times b) the acid leach was performed using 5.0M H 2 S0 4 at 87 0 C for 2 hr.

TABLE 6

XRF

Analyses TiO 2 Fe 2 0 3 (total Fe ThO 2 SiO 2 A1 2 0 3

S*

Ilmenite feed (Eneabba North) 59.99 34.12 0.051 1.00 0.64 Time of caustic leach (min) 15 min 30 min 60 min 61.31 61.35 61.21 34.26 34.04 34.12 0.021 0.016 0.016 0.64 0.64 0.53.

0.44 0.39 0.35 r a goo.

.00# 6 4 EXAMPLE7 14 To demonstrate the effect of the time used in the acid leach These experiments were performed as described in Example 1 except that a) the caustic leach was performed using 4.OM NaGH at 75 0 C for 1 hr b) the acid leach was performed using 5.OM H 2 S0 4 at 87 0 C for various times.

TABLE7 XRF flmenite feed Time of acid leach (hr) Analyses (Eneabba North) 0.5 hr 1 hr TiO 2 59.99 62.54 61.53 Fe 2

O

3 (total Fe) 34.12 34.97 34.10 *ThO-2 0.051 0.018 0.016 ::SiO 2 1.00 0.42 0.43 A1 2 0 3 0.64 0.37 0.34 63.09 35.03 0.012 0.45 0.34 EXAMPLE 8 To demonstrate the effectiveness of the caustic/acid leach on other ilmenites Ilmenites from Eneabba West and Eneabba North were leached with 2.5 molar sodium hydroxide for 1 hour at 75oC in the apparatus described in Example 1. The products were washed and then leached with 3 molar sulphuric acid for 2 hours at 0 C. These products are referred to as "caustic/acid" in Tables 8 and 9 below.

Other samples of the same ilmenites were treated as described above except that the acid leach was not preceeded by a sodium hydroxide leach. These products are referred to as "apid only" in Tables 8 and 9 below.

*fee*: TABLE 8 SLeaching procedure XRF Analysis Ilmenite feed caustic/acid acid only Eneabba West TiO 2 62.6 63.5 62.6 Fe 2 0 3 (total Fe) 32.9 31.2 31.0 A1 2 0 3 0.83 0.49 0.63 SiO 2 1.10 0.56 0.99 Th 0.0311 0.0073 0.0153 U 0.0009 0.0008 0.0011 TABLE 9 to*: XRF Analysis TiO 2 3 (total Fe) A1 2 0 3 SiO 2 Th

U

Ilmenite feed 60.4 34.0 0.62 0.99 0.0535 0.0012 61.8 60.7 34.0 33.5 0.36 0.50 0.46 0.93 0.00142 0.0277 0.0005 0.0006 -16- EXAMPLE 9 To demonstrate the effect of carrying out the acid leach in the presence of added fluoride.

100 g of ilmenite was leached with 150 cm 3 of 0.2 molar sodium hydroxide solution at 75 "C for 90 mins using the apparatus described in Experiment 1. The product was thoroughly washed with water, then leached with 300 cm 3 of 5 molar sulphuric acid containing 0.1 molar sodium fluoride, at 87 °C for 120 mins in the same apparatus. The product was again washed with water. This product is referred to as "caustic/acid/fluoride" in Table 10 below.

Another sample of the same ilmenite was treated as described above except that Sthe caustic leach was omitted. This product is referred to as "acid/fluoride" in S 15 Table A further sample of the same ilmenite was treated as described above for the "caustic/acid/fluoride" product except that the acid leach did not contain sodium fluoride. This product is referred to as "caustic/acid" in TABLE Leaching Procedure XRF analysis ILMENITE FEED caustic/ acid/ caustic/ (ENEABBA NTH) acid/ fluoride acid fluoride TiO 2 61.51 63.25 63.12 63.16 Fe 2 0 3 (total 35.04 34.98 35.22 35.13 Fe) ThO 2 0.047 0.008 0.017 0.024 SiO 2 1.08 0.71 0.97 0.84 A1 2 0 3 0.61 0.29 0.34 0.47 920414,gjnspe.007,AMC.C,16

Claims (21)

1. A process for facilitating removal of radionuclides from titaniferous material which comprises the steps of subjecting said titaniferous material to a treatment in a manner to alter the state or condition of radionuclides in the material for a more effective subsequent acid leach, and thereafter leaching the titaniferous material with acid, to dissolve radionuclides, wherein the conditions of said treatment and said leach are such that titanium and iron are substantially not dissolved from the material.

2. A process according to claim 1 further comprising separating the radionuclides from the titaniferous material.

3. A process according to claim 1 or 2 wherein said treatment comprises a 15 treatment of the titaniferous material with aqueous basic solution under S" conditions effective to achieve said alteration of the state or condition of the radionuclides but such that iron and titanium are substantially not dissolved from said material.

4. A process according to claim 3 wherein said basic solution is an aqueous solution of an alkali metal oxide or hydroxide.

5. A process according to claim 3 wherein said basic solution is an aqueous solution of sodium hydroxide.

6. A process according to claim 4 or 5 wherein said solution is of a concentration no greater than 15 molar.

7. A process according to claim 4, 5 or 6 wherein said solution is of a concentration greater than 0.1 molar. 920415,gnspe.007,AMC.C2,17 -18-

8. A process according to any one of claims 3 to 7 wherein said treatment includes maintaining said basic solution at a temperature greater than 50 °C.

9. A process according to claim 8 wherein said temperature is not greater than 125 °C. A process according to any preceding claim wherein said radionuclides removed include thorium radionuclides and/or uranium radionuclides.

11. A process according to any preceding claim wherein said titaniferous material comprises ilmenite, altered ilmenite, reduced ilmenite or synthetic rutile.

12. A process according to any preceding claim wherein said acid is a mineral acid.

13. A process according to any one of claims 1 to 11 wherein said acid is sulphuric acid.

14. A process according to any preceding claim further including the step of washing the titaniferous material after said treatment and before said acid leaching. &oo U

15. A process according to any preceding claim wherein said acid leach is effected with an acidic solution of concentration no greater than 10 molar,

16. A process according to any preceding claim wherein said acid leach is effected with an acidic solution of concentration greater than 0.1 molar.

17. A process according to any preceding claim including maintaining the acid leach solution at a temperature greater than 50 0 C. 920415,gjnspe.007,AMC.C2,18 -19-

18. A process according to claim 17 including maintaining the acid leach solution at a temperature not greater than 125 °C.

19. A process according to any preceding claim wherein the solids concentration is not more than about 75% w/w solids, and the process is performed on a stirred suspension in a heated reactor. A process according to any one of claims 1 to 18 wherein the solids concentration is greater than 75% w/w solids and the process is performed on an appropriately wetted solid in saggers in an oven, or in a rotary kiln.

21. A process according to any preceding claim wherein said treatment and/or acid leach are also effective to dissolve impurities including at least one of AI 2 0 3 and SiO 2

22. A process according to any preceding claim wherein said acid leach is carried out in the presence of added fluoride in an amount effective to further enhance dissolution of the altered radionuclides but substantially without dissolving titanium from the titaniferous material.

23. A process according to any preceding claim, carried out at or close to atmospheric pressure. :24. Titaniferous material from which radionuclides have been removed by the process of any preceding claim. A process according to claim 1 substantially as set forth in one or more of the Examples. 9204 16gjnspe.007,AMC.C2,19 20 D ted this 16th da~ of April, 1992 1M My"143R1L SYAIND-+ By its Patent Attorneys Davies Collison Cave so&* 9204 16,gnspe.007,AMC.C2,20 TRUE COPY -21 ABSTRACT A process for facilitating removal of radionuclides from titaniferous material which comprises the steps of subjecting said titaniferous material to a treatment in a manner to alter the state or condition of radionuclides in the material for a more effective subsequent acid leach, and thereafter leaching the titaniferous material with acid, to dissolve radionuclides, wherein the conditions of said treatment and said leach are such that titanium and iron are substantially not dissolved from the material. 0..9 9 0:00 SO 06e* k *o•o 920416,gjnspc.007,amcc2.abs,21