Abstract: Methods for preparing and using a photocatalyst are described. The catalyst is prepared by oxidation of a metal salt which has been doped in situ to form a photocatalyst active in visible light. The photocatalyst is used for degrading toxic and irritating compounds and infectious agents.

Abstract: A sulfate process for producing titania from a titaniferous material (as herein defined) including a step of leaching said titaniferous material with a leachant to form a process solution that includes an acidic solution of titanyl sulfate and iron sulfate, wherein said sulfate process further includes a filtration step comprising filtering said leachant to at least substantially remove titanyl sulfate particles from said leachant prior to supplying said leachant to said leach step.

Abstract: A process for synthesizing nano-sized rutile, anatase, or a mixture of rutile and anatase TiO2 powder. The process includes the steps of: 1) forming a Ti-peroxo complex by mixing H2O2 with a Ti compound, and 2) heating the Ti-peroxo complex at a temperature of above 50° C. A primary particle size of TiO2 particles, synthesized by the method, is below 50 nm, and an agglomerated particle size thereof after a washing/dry process is below about 10 ?m. The major characteristics of the present invention are that it is a low temperature process, a highly concentrated synthesis, and high production yield of above 90%.

Abstract: The present invention provides a magnetic sheet with improved resistance to folding while maintaining good magnetic characteristics and reliability; a method for producing the magnetic sheet; an antenna; and a portable communication device. A magnetic sheet of the present invention includes a flat magnetic powder, and a resin binder capable of dissolving in a solvent, wherein the magnetic sheet has a gradient of the content ratio of the magnetic powder to the resin binder in a thickness direction thereof, wherein, in use, the magnetic sheet is folded so that, of the front and back surfaces thereof, one surface whose magnetic powder content is lower than that of the other is folded inward, and wherein the difference in glossiness measured at a light-incident angle of 60° between the front and back surfaces is 9.4 or more.

Abstract: A sulfate process for producing titania from a titaniferous material (such as an iron-containing titaniferous material; such as ilmenite) is disclosed. The process includes precipitating titanyl sulfate from a process solution produced in the process. The titanyl sulfate precipitation step includes subjecting the precipitated titanyl sulfate to a shearing action during the course of precipitating titanyl sulfate from the process solution or after precipitation has been completed.

Abstract: A method for making a metal-titania pulp and photocatalyst is provided, including firstly acidically hydrolyzing a titanium alkoxide solution in presence of an alcohol solvent to get a colloidal solution; then, adding at least one metal salt solution into the colloidal solution to produce a nano-porous metal/titania photocatalyst under appropriate conditions by appropriate reaction. The nano-porous metal/titania photocatalyst thus prepared has excellent optical activity and is applicable in research of water decomposition with light to improve production efficiency of hydrogen energy. In addition, the photocatalyst is further processed in the form of powder or film to facilitate industrial application in wastewater treatment.

Abstract: This invention relates to methods of making single phase nanocrystalline titanium dioxide. It is hereby provided a method for preparing single-phase anatase type titanium dioxide photocatalyst having a particle size of nano level at near room temperatures without the need for a sintering process at high temperatures.

Abstract: The present invention relates to a titania sol, a method of preparing the same, and a coating composition including the same. More specifically, it relates to a titania sol prepared by elevating the temperature of a reactant solution including a precursor of titania in a solvent for a reaction temperature, adding an acid catalyst to the reactant solution and conducting a sol-gel reaction while removing the solvent for reaction therefrom, and drying the prepared titania sol and re-dispersing the dried titania in a solvent for dispersion, a method of preparing the same, and a coating composition including the same.

Abstract: A method of preparing stable, transparent photocatalytic titanium dioxide sots is disclosed which involves thermal treatment of a suspension of amorphous titanium dioxide in the presence of certain alpha-hydroxy acids. The sots comprise titanium dioxide particles in the anatase form having a crystallite size less than about 10 nm and exhibit excellent stability and transparency at basic, neutral, and acid pH.

Abstract: A method of preparing stable, transparent photocatalytic titanium dioxide sols is disclosed which involves thermal treatment of a suspension of amorphous titanium dioxide in the presence of certain alpha-hydroxy acids. The sots comprise titanium dioxide particles in the anatase form having a crystallite size less than about 10 nm and exhibit excellent stability and transparency at basic, neutral, and acid pH.

Abstract: The invention provides a method for the formation of small-size titanium oxide particles, comprising the steps of a) preparing a starting aqueous solution comprising at least one of titanic ions and complexes thereof, at a concentration of at least 0.1% w/w titanium; b) maintaining the solution at a temperature lower than 70° C. for a retention time in which hydrolysis takes place, the extent of the hydrolysis being sufficient to produce O.i mmol protons per mmol of titanium present in solution, wherein the time does not exceed 14 days, to form a system containing a retained solution; and c) adjusting the conditions in the system by at least one of the steps of: i) heating the retained solution to elevate the temperature thereof by at least 1° C.; ii) changing the pH of the retained solution by at least 0.1 units; and iii) diluting the retained solution by at least 20% whereby there are formed particles, wherein the majority of the particles formed are between about 2 nm and about 500 nm in size.

Abstract: The invention provides a method for the Industrial purification of a titanium feed stream of purity P1, by the formation of a titanium-double-salt precipitate of purity P2 and a titanium solution with purity P3, wherein P2>P1>P3, the method comprising the steps of: i. forming, from the feed, a medium comprising water, titanium ion, a cation selected from the group consisting of ammonium, cations of alkali metals, protons and a combination thereof, and an anion selected from the group consisting of OH, SO4, HSO4, halides and a combination thereof, which formed medium is further characterized by the presence of (a) a double-salt precipitate comprising titanium ion, at least one of the cations and at least one of the anions; and (b) a titanium solution; and wherein the concentration of the anion in the titanium solution is higher than 15% and the ratio between the concentrations of the cation and the anion in the titanium solution is higher than 0.2 and lower than 1.6; and ii.

Abstract: A composite photocatalyst includes a semiconducting core and a nanoscale particle disposed on a surface of the semiconducting core, wherein the nanoscale particle is an electron carrier, and wherein the photocatalyst is sensitive to visible light irradiation.

Abstract: A sulfate process for producing titania from a titaniferous material is disclosed. The process includes leaching the titaniferous material and producing a leach liquor, separating titanyl sulfate from leach liquor, hydrolysis of the extracted titanyl sulfate, and thereafter calcining the solid phase produced in the hydrolysis step. The process is characterised by controlling the hydrolysis step and forming a selected particle size distribution of hydrated titanium oxides from titanyl sulfate.

Abstract: A sulfate process for producing titania from a titaniferous material is disclosed. The process includes leaching the titaniferous material and producing a leach liquor, precipitating iron sulfate from the leach liquor, solvent extraction of titanyl sulfate from leach liquor, hydrolysis of the extracted titanyl sulfate, and thereafter calcining the solid phase produced in the hydrolysis step. The process is characterised by using at least part of the raffinate from the solvent extraction step as at least part of the leach solution in the initial leach step.

Abstract: A titanium oxide powder holding a barium compound on the surface of the particles thereof is used for manufacturing a highly crystalline fine barium titanate powder by solid-phase reaction. When the titanium oxide powder and a barium-containing powder material are mixed and calcined to prepare the barium titanate powder, the barium compound on the surfaces of the titanium oxide powder particles inhibits the sintering, or the growth, of the titanium oxide during the calcination. Consequently, the resulting barium titanate powder is highly crystalline and fine.

Abstract: A sulfate process for producing titania from titaniferous material is disclosed. The process includes precipitating titanyl sulfate from leach liquors containing acidic solutions of titanyl sulfate. The process is characterised by: (a) multiple stage leaching to produce leach liquors containing acidic solutions of titanyl sulfate; (b) using depleted leach liquor from a titanyl sulfate precipitation reactor in the leach steps; and (c) controlling acid concentration in the leach steps to avoid premature hydrolysis and premature precipitation.

Abstract: The invention relates to a photocatalyst containing titanium dioxide, to a method for using it and to its application. A sulphurous titanium dioxide hydrate precipitate is precipitated from an acid titanium oxysulphate solution at a temperature below the boiling point of the solution, e.g. in the range from 70 to 100° C., using crystal nuclei and without addition of base. The precipitate is separated, washed and calcinated. The photocatalytic titanium dioxide thus obtained has a specific area in the range from 100 to 250 m2/g and a 0.3 to 5% sulphur concentration. Catalytic activity has been confirmed in asetal dehyde decomposition and in anionic (SNC?)2 radical formation.

Abstract: Processes for the efficient and economical beneficiation of titaniferous ore are provided. A unique process for beneficiating ore comprising pretreatment of the ore by oxidation and reduction, followed by acid leaching with sulfuric acid has been developed. The acid used in this process may be recycled, which will thereby increase the efficiency of the process. Preferably the ore treated according to the present invention is ilmenite ore.

Abstract: Titanium dioxide-calcium carbonate composite particles capable of realizing characteristic properties inherent in titanium dioxide such as a high opacity, a process for producing the same, and a complex composition or complex incorporated with the same are provided. The composite particles were prepared by adding titanium dioxide particles having an average particle diameter of 0.1 to 0.5 ?m in a carbonation step, typically a step of introducing a gaseous mixture of carbon dioxide and air into a calcium hydroxide slurry with stirring, to conduct a carbonation, and continuing the reaction till pH of the slurry becomes 7 by continuous introduction of the gaseous mixture. Moreover, by incorporating the formed composite particles, complexes such as coatings and paints for paper making or composite materials such as paper, plastic molded materials, and rubber molded materials are produced.

Abstract: A process for producing a titanium oxide is provided which comprises the steps of (i) mixing an acidic solution of a titanium compound with a nitrogen-containing basic organic compound to obtain a reaction product and (ii) calcining the obtained product. The titanium oxide exhibits a high photocatalytic activity by visible light radiation.

Abstract: Nanoparticulate titanium dioxide coating produced by educing flocculates of titanium dioxide nanoparticles from a titanyl sulfate solution and dispersing the nanoparticles in a polar sol-forming medium to make a sol suitable as a coating usable to impart photocatalytic activity, U.V. screening properties, and fire retardency to particles and to surfaces. The photocatalytic material and activity is preferably localized in dispersed concentrated nanoparticles, spots or islands both to save costs and leverage anti-microbial effects.

Abstract: The present invention relates to titanium oxide particles having an average particle size of not more than 0.3 &mgr;m, and a BET specific surface area of 15 to 200 m2/g, containing a soluble sodium salt of not more than 230 ppm, calculated as Na, and a soluble sulfate of not more than 150 ppm, calculated as SO4, and having a pH value of not less than 8. The titanium oxide particles of the present invention are suitable as non-magnetic particles for a non-magnetic undercoat layer of a magnetic recording medium which uses magnetic particles containing iron as a main ingredient, and even more particularly, are suitable as non-magnetic particles for a non-magnetic undercoat layer of a magnetic recording medium which uses magnetic particles containing iron as a main ingredient, show an excellent dispersibility in a binder resin, contain only a small amount of soluble sodium salt and soluble sulfate, and have a pH value of not less than 8.

Abstract: A titanyl sulfate solution or a titanium tetrachloride solution is neutralized with an alkali to form orthotitanic acid, to which hydrochloric acid is added such as to adjust the TiO.sub.2 concentration to 80-140 g/L and the HCl concentration to 90-150 g/L and a synthesis reaction is performed at a temperature of 25-60.degree. C. to produce titanium oxide particles in which needles aggregate and/or bind together to yield fan-shaped particles.

Abstract: A process for production of titanium oxide comprises digesting an ilmenite ore in which at least 92% by weight of the iron which is present is in the ferrous form, if necessary adding a reducing agent and subsequently precipitating hydrous titanium oxide. When a reducing agent is added the amount used is equivalent to less than 4.0% by weight metallic iron calculated with respect to ilmenite ore. The process enables an increased throughput on a pigment plant and less co-product in the form of iron compounds is produced.

Abstract: Titanium dioxide pigments are obtainable by complete hydrolysis of a hydrolyzable titanium compound at from 0 to 100.degree. C. with intensive stirring and with setting of a pH in the range from 3 to 8 and maintenance of this pH within a range of 0.3 units.The titanium dioxide pigments can be employed for the production of cosmetic preparations and medicaments.

Abstract: The present invention relates to nanodisperse titanium dioxide, to a process for the production thereof and to the use thereof.

Abstract: An ultrafine titanium dioxide powder is disclosed that can be produced by hydrothermal treating an amino titanium oxalate composition. Ultrafine titanium dioxide powders are useful in cosmetic and other applications for controlling exposure to ultraviolet (UV) light.

Abstract: A process for preparing anatase titanium dioxide by precipitating hydrous titanium oxide in the absence of added nuclei from a solution of titanium sulphate containing the equivalent of 200 to 300 grams TiO.sub.2 per liter and having an acid to titanium ratio in the range 1.6:1 to 2.2:1, the precipitation being induced by the addition of 5 to 35 parts water per 100 parts titanium sulphate solution. The hydrous titanium oxide is calcined in the presence of an amount of potassium compound equivalent to between 0.20 and 0.60 weight percent calculated as K.sub.2 O based on TiO.sub.2 and between 0.15 and 0.55 weight percent phosphorus calculated as P.sub.2 O.sub.5 based on TiO.sub.2. The hydrous titanium oxide is subjected to calcination in a process having a specified thermal profile. The product of the process is anatase titanium dioxide having an average crystal size larger than conventionally prepared anatase. Said product is easily milled to form a product with a high single crystal fraction.

Abstract: A titanium oxide hydrolysate slurry prepared by the sulfate process is treated with either an alkali metal hydroxide or an alkali metal carbonate to solubilize the sulfur bound to the titanium at a temperature of from 60.degree. C. to 120.degree. C. and the slurry is treated with an organic acid to remove the alkali metal compounds present. This process produces titanium oxide hydrolysate of high purity.

Abstract: A process for the preparation of very pure titanium dioxide by reacting titanium tetrahalides with sulphuric acid, hydrolysis the titanyl sulphate solution obtained and calcining the hydrolysate is disclosed wherein the reaction between titanium tetrahalide and aqueous 20-40% by weight strength sulphuric acid is performed in such a way that crystallisation of titanyl sulphate does not take place, the hydrogen halide is separated, the solution is optionally concentrated and filtered and then the ratio by weight of sulphuric acid to titanium dioxide is adjusted to between 1.7 and 2.0 and the titanium dioxide concentration is adjusted to between 250 and 300 g/l, the solution is hydrolyzed and the resulting titanium oxide hydrate is filtered off and calcined to give Futile or anatase.

Abstract: The invention relates to a method of preparing microcrystalline titanium dioxide, in which a) the solid titanium dioxide hydrate is treated with a base, b) the precipitate treated with the base is treated with hydrochloric acid, and c) the precipitate treated with the base and the hydrochloric acid is neutralized. It has been noted that useable rutile crystals, a more appropriate crystal size and crystal size distribution and that chemicals can be saved if as the final hydrochloric acid content of the stage a) is adjusted a lower value than usually, being about 8 to 25 g/liter, for the precipitation of microcrystalline titanium dioxide. Hereby the neutralization of the stage c) can also be carried out by raising the pH to a lower value than usually, i.e. the value about 4.0 to 6.0.

Abstract: The production of titanium dioxide by the sulphate process generates waste substances such as the wash filtrates, which are formed in the washing of titanium dioxide hydrate, and waste gases which contain sulphur dioxide. In this improved process the wash filtrate is used to remove the sulphur dioxide from the waste gas while the sulphuric acid content of the wash filtrate is raised and the sulphuric acid-containing process solution thus obtained is used within the scope of the titanium dioxide production process. The waste gas and the wash filtrate are passed countercurrently through a series of several washing steps and are contacted with each other by introducing the wash liquid into the waste gas in a finely divided form in scrub towers. The sulphuric acid content of the washing fluid is stepwise changed from washing stage to washing stage. The sulphur dioxide content of the waste gas is reduced to values that may be discharged into the ambient atmosphere.

Abstract: A method of growing a single crystal of KTiOPO.sub.4 which is a nonlinear optical material is disclosed. Growth of the single crystal of KTiOPO.sub.4 is carried out by melting a KTiOPO.sub.4 material with a flux to produce a melt, then contacting a seed crystal to the melt, and by slowly cooling at a saturation temperature or below. At this time, molar fractions of K.sub.2 O, P.sub.2 O.sub.5 and TiO.sub.2 contained in the melt fall within a region surrounded by six point in a K.sub.2 O-P.sub.2 O.sub.5 -TiO.sub.2 ternary phase diagram of A (K.sub.2 O:0.4150, P.sub.2 O.sub.5 :0.3906, TiO.sub.2 : 0.1944), B (K.sub.2 O:0.3750, P.sub.2 O.sub.5 : 0.3565, TiO.sub.2 : 0.2685), C (K.sub.2 O: 0.3750, P.sub.2 O.sub.5 : 0.3438, TiO.sub.2 : 0.2813), D (K.sub.2 O: 0.3850, P.sub.2 O.sub.5 : 0.3260, TiO.sub.2 : 0.2890), E (K.sub.2 O: 0.4000, P.sub.2 O.sub.5 : 0.3344, TiO.sub.2 : 0.2656), and F (K.sub.2 O: 0.4158, P.sub.2 O.sub.5 : 0.3744, TiO.sub.2 : 0.2098). In addition, K.sub.15 P.sub.13 O.sub.

Abstract: Disclosed is a process for producing a titanium dioxide pigment used for a resin-coated paper type photographic support, comprising the following steps:(a) a step of adding at least one alkaline earth metal compound in an amount of 0.01-2.0% by weight in terms of a metal oxide based on the titanium dioxide before calcination step and(b) an acid-washing step of washing the titanium dioxide at acidic state after the calcination step and before a step of surface treatment with a hydrated metal oxide,and wherein particle size of the titanium dioxide pigment is 0.110-0.150 .mu.m shown by number-average diameter obtained by measuring the diameter in a certain direction using an electron microscope.A photographic support which comprises the above titanium dioxide pigment is also disclosed.Occurrence of die lip stain and microgrit are substantially restrained in this photographic support and a photographic material made of it shows improved image sharpness.

Abstract: The present invention provides novel titanium dioxide aggregates especially suitable for an electrophotographic photosensitive material. This titanium dioxide aggregates comprise sintered aggregates of fine primary particles and have a rutile type crystal structure and an oil absorption of 35-65. This titanium dioxide aggregates which are treated with a mineral acid is also provided. There is also provided an electrophotograpic photosensitive material which contains such titanium dioxide in a photosensitive layer.

Abstract: There is provided a method of producing titanium oxides which comprises: admixing an aqueous solution of titanium tetrachloride with sulfuric acid in a molar ratio of sulfuric acid to titanium tetrachloride of at least 0.5 adding an alklai to the resultant solution to produce titanium hydroxide; and drying and calcining the titanium hydroxide. A further method is provided which comprises: adding a solution of an alkali to an aqueous solution of titanium tetrachloride having a concentration of not more than 2.5 moles/l at temperatures of not less than 50.degree. C., thereby to substantially thermally hydrolyze the titanium tetrachloride and to produce titanium hydroxide; and drying and calcining the titanium hydroxide.

Abstract: In the production of TiO.sub.2 pigments by the steps of digesting titanium-containing raw materials with sulfuric acid, hydrolyzing the titanyl sulfate obtained, separating the waste acid from the hydrolyzate, bleaching the hydrolyzate and calcining the hydrolyzate after addition of rutilizing nuclei and standardizing chemicals to form TiO.sub.2 pigments, and recovering sulfuric acid from the waste acid, the improvement which comprises employing as the rutilizing nuclei nuclei produced from part of the bleached and then washed hydrolyzate, which nuclei are added to the remainder of the bleached and washed hydrolyzate before calcination.

Abstract: A titanium dioxide composition useful as the opacifier agent for vitreous enamels and fusion enamels comprises TiO.sub.2 predominantly in the form of isometric primary particles from 0.5 to 5.0 .mu.m in size, which are aggregated to predominantly spherolithic particles 1 to 100 .mu.m in diameter, with a BET surface of 1 to 4.5 m.sup.2 /g and an apparent density of 0.2 to 1.3 kg/1, is prepared by subjecting titanium dioxide hydrate having a BET surface of from 50 to 500 m.sup.2 /g to accelerated calcination at temperatures of 800.degree. to 1600.degree. C.

Abstract: Poorly crystallized or amorphous TiO.sub.2 particulates having a mean particle size greater than 20 nm are prepared by thermally hydrolyzing a titanium compound in solution, in the presence of at least one carboxylic acid containing a hydroxyl and/or amino group, or an organophosphoric acid; the TiO.sub.2 particulates thus produced are readily molded/extruded into useful shaped articles, e.g., catalysts or catalyst supports, having good porosity and mechanical properties.

Abstract: A process for the preparation of an improved quality TiO.sub.2 pigment by hydrolysis of titanyl sulphate, isolation of the hydrolysis product form the waste acid produced during the hydrolysis, washing of the hydrolysis product and calcination of the hydrolysis product to form the TiO.sub.2 pigment, wherein the hydrolysis of the titanyl sulphate is carried out using separately produced hydrolysis nuclei which have been produced by a reaction of titanium salts with alkaline reagents, and in which waste acid and/or wash liquid containing waste acid is added after at least 50% of the total duration of the hydrolysis process.

Abstract: High-grade titanium dioxide is produced by(a) reacting ilmenite or titanium-containing slag with sulfuric acid,(b) dissolving the material from (a) with water or dilute sulfuric acid,(c) separating insolubles from (b) to obtain a black solution containing titanyl sulfate and foreign metal salts,extracting titanyl sulfate from the black liquor with sulfuric acid and an organic medium containing an organophosphorus compound, separating the foreign metal salts in an aqueous extract phase, recovering titanyl sulfate from the organic extract phase, andhydrolyzing the titanyl sulfate to titanium oxide hydrate.

Abstract: A process for the production of TiO.sub.2 pigments by the sulfate process by digestion of titanium-containing raw materials with sulfuric acid, hydrolysis of the titanyl sulfate formed, purification of the hydrolyzate and calcination of the hydrolyzate in rotary kilns, wherein the calcination conditions are regulated through adjustment of the SO.sub.2 content of the waste gases issuing from the rotary kilns used for calcination.

Abstract: A process for preparing titanium dioxide in the form of spherical particles having the particle size distribution indicated by dw/dn.ltoreq.2, by hydrolysis of strongly acid solutions of Ti(IV), wherein the molar ratio SO.sub.4.sup.= /Ti(IV) is at least 1.5, and in the presence of cationic polyelectrolytes having a molecular weight higher than 1 million and a ionicity of at least 3 milliequivalents per gram.

Abstract: A titanium dioxide compositon suitable for incorporation into ceramic frit, and process for preparation thereof. A clarified titanium sulfate liquor is hydrolyzed and precipitated to yield relatively large and uniform-sized hydrolysate particles which are easily separated from the acidic liquor by filtration.

Abstract: A process for preparing high quality titanium dioxide which exhibits excellent reflectance and tint strength when incorporated into a coating formulation. The process involves the preparation of a seed solution wherein one of the seed curing factors of time, temperature and amount of alkaline neutralizing agent are varied to establish maximum reflectance and tint strength values obtained by the final product. The process can be repeated to analyze one or both of the other factors. The process can be used to prepare titanium dioxide in the anatase or rutile form and on a batch or continuous basis.

Abstract: A novel titanium dioxide hydrate is provided whose structure exhibits X-ray diffraction peaks at 24.6.+-.0.4.degree. and 48.+-.0.4.degree., and which is suitable as an adsorbent material. A process for preparing the novel titanium dioxide hydrate also is provided which includes hydrolyzing a specific titanium sulfate solution and thereafter flocculating colloidal titanium dioxide hydrate by the addition of a monobasic acid and recovering the titanium dioxide hydrate.

Abstract: Titanium dioxide of improved properties for use as a pigment is obtained by a process in which a non-concentrated acid solution containing not more than 200 grams of TiO.sub.2 per liter of solution is partially hydrolyzed and filtered; and additional acid solution slowly added with heating to hydrolyze the remaining TiO.sub.2 and give a product which, on calcining has a color index of about 1500.

Abstract: Hydrolysis of a titanyl sulphate solution is carried out according to the autonucleation method of gradually adding the solution to a body of water at a substantially constant rate over 10-20 minutes, in such a way as to obtain an ionic concentration after one minute of feeding of from 75 to 105 g/l, the concentration of sulphuric acid in the final hydrolysis solution being regulated to a value of from 310 to 330 g/l by adding water from the commencement of clouding of the hydrolysis solution up to the end of hydrolysis.

Abstract: Production of titanium dioxide which is characterized by recovery of reusable H.sub.2 SO.sub.4, highly pure Fe oxide and hydroxide and fractional recovery of Mn, V and Cr, etc., from FeSO.sub.4. nH.sub.2 O and waste acid of 20 - 40% H.sub.2 SO.sub.4 containing abundant heavy metallic ions, which are by-produced in the production of TiO.sub.2 by dissolution of Ti raw materials such as ilmenite, steel production slag, such as electric furnace slag, convertor slag with H.sub.2 SO.sub.4.