KR0160753B1 - Production of acid soluble titania - Google Patents

Abstract

The present invention is a method for preparing acid-soluble titania. This method comprises the steps of: (1) adding magnesium or manganese compounds to the titanium iron ore if the magnesium or manganese content is insufficient in titanium iron ore, and (2) sufficiently high temperature and sufficient time in the presence of the reducing agent. Heating to reduce iron-containing compounds to iron metal, and titania is converted to an acid-soluble form so that it can be present, (3) cooling the ore, and (4) the aqueous aeration step. It is made to separate the step. Titanium iron ore contains insufficient magnesium and manganese if the following equation is not satisfied. (1.98a + 1.14b) /d≥0.08, where a is the weight percent of MgO contained in the ore, b is the weight percent of MnO contained in the ore, and d is TiO ₂ contained in the ore % By weight. Magnesium or manganese compounds are either oxides or compounds that can be converted to oxides under reaction conditions. The aqueous aeration technique of the present invention employs a metal ion sequestrant capable of blocking metal ions from the ore without locally reducing the pH to a significant extent during the time of iron oxide formation at points away from the ore. Such metal ion sequestrants include citric acid.

Description

[Name of invention]

Method for preparing acid-soluble titania

[Background of invention]

The present invention relates to a process for the preparation of acid soluble titania products. An important application of titania-containing ores is to use them as a source for the production of white titania pigments. Pigment manufacturing processes include two types of selective processes, chlorine and sulfate treatment. In particular, the field of interest in the present invention is a pigment production method using sulfate, which is less limited in composition or particle size distribution as an ore source compared to the method using chlorine.

Particular requirements of the sulphate treatment process for pigment production are that the ore source is essentially soluble in strong sulfates. In the case of naturally occurring titanium containing ores, this requirement is only met if it is a material obtained by transforming ilmenite ore (FeO.TiO ₂ ) to a strictly limited rutile and ferric titanate. However, synthetic sources of acid-soluble titania are possible in the form of slag products obtained by dissolving ilmenite. Slag products (75-85 TiO ₂ ) are significantly higher quality compared to acid-soluble ilmenite (less than 58% TiO ₂ ) and are preferred for sulphate pigment makers where oxygen monoxide or residue disposal is a problem.

In the preparation of sulfate pigments, the ilmenite source has the disadvantage of low titania content, while the slag source requires dangerous and unpredictable dissolution conditions and has the dual problem of incomplete titania recovery in dissolution and subsequent dissolution.

Not all acid soluble ilmenites are suitable for pigment production, either through the sulphate preparation process or by upgrading to slag. In particular, ilmenite having Cr ₂ O ₃ higher than about 0.15% Cr ₂ O ₃ can not be applied directly or indirectly in the manufacture of sulfate pigments because chromium causes serious problems in the color of the pigment product. The relatively high iron content (especially compositions with excess FeO.TiO ₂ ) and gangue content (e.g. containing about 5% total alumina and silica) are not suitable for upgrading to suitable slag products, There is no economic competition with other sources of sulphated pigment production.

In recent years, the use of ilmenite as a source of sulphate pigments has been recognized that this relatively large amount of acid and iron sulphate by-products can flow into waterways or oceans, potentially damaging the environment. Therefore, there is a tendency to use sources such as slag, which consume less acid and produce a small amount of byproducts, in the production of sulfate pigments. Conversely, acid recovery schemes, which are expensive in terms of equipment and energy costs, have been used to limit emissions. These costs are much reduced when using slag than ilmenite.

In summary, slag is more useful than ilmenite as a source of sulfate process.

(Ⅰ) low acid consumption.

(Ii) By-product waste is reduced in quantity.

(Iv) Acid regeneration requirements are reduced.

(Iii) The cost of mailing and processing is low.

However, the relative price of slag and ilmenite and the limitations of slag availability remain to be a source of interest for ilmenite in the sulfate pigment process.

Considering the availability and relative price of ilmenite and slag, the main focus is the scale of the process required to control the expense of dissolving ilmenite into slag.

Most ilmenite makers are not preferably placed relative to existing dissolvers unless they are large enough to support these cost adjustments and are in close contact with specific ore-producing sites.

Currently, the opportunity to supply more suitable upgraded materials, such as slag, to ilmenite makers in the sulfate pigment process is limited. In addition, it is not possible to economically treat a deformable titanium ore source (eg, lococene or rutile) for the production of acid soluble titania products.

Accordingly, it is an object of the present invention to provide a method for preparing an acid-soluble titania product having the following conditions.

(Iii) The product should be economically formed with a process scale of less than 25% of the conventional slag manufacturing process.

(Ii) The titanium content of the product should be equal to or higher than the range of the titanium content mixed with the slag product.

(Iii) The Titanium ore source for the product may be an ore not ilmenite. Ilmenite, which is not a suitable source for the sulphate pigment process or is suitable for slag production, should be able to be upgraded to a useful product with suitable treatment.

(Iii) In sulphated pigments, acid solubility and titanium regeneration should be greater for the product than for the conventionally available slag products.

(Iv) The process must be operable under physical conditions that can be obtained economically and sustainably.

[Private Technology]

Processes for the preparation of high quality acid soluble titania obtained from natural ore without the need to dissolve into slag products are described by Martin and Hawkin (US Pat. No. 3,502,460, Mar. 24, 1970). In this conventional process, the magnesium compound is treated by high temperature combustion treatment before the titanium-containing ore is reduced in a rotary furnace having a temperature of 1200 to 1300 ° C. The resulting titania matrix containing the resulting metallic iron as encapsulated subgrains can be dissolved in hydrochloric acid. However, there is no suggestion on the removal of metallic iron, which can avoid the production of efficient, economical and environmentally problematic iron residues.

An efficient method for removing metallic iron by water soluble aeration in the presence of additives is described in Australian patent 247110 (January 1961-Bece). In this case, however, the metal is removed from the matrix consisting of titania, which has a structure that is not acid soluble, from which the ferrous metal can actually be removed faster than the acid soluble matrix.

A logical advance from the prior art would be to combine the iron removal process described by Bech with the combustion treatment and reducing conditions required to form the acid soluble titania matrix described by Martin and Hockin. In this way economically acid soluble titania products can be formed into shapes similar to those used to form synthetic rutile from Western Australian Ilmenite. Despite the considerable motivation for this process advance, acid soluble titania products have not been successfully produced under industrially practical conditions.

It is substantially more difficult to economically produce acid soluble titania from natural ores than suggested in the above-mentioned prior art literature. The reason for this is as follows.

(Iii) The necessary additives (particularly magnesium raw materials) are not easily incorporated into titania matrices during oxidation or reduction roasting. High temperature reduction (usually 1200-1300 ° C.) and the most suitable natural ore are necessary to allow the dispersion of homogeneous additives in the photoelectric carbon bed with less than two hours of remaining time. This is despite the claims of the prior art that reduction can occur even at temperatures as low as 1130 ° C. with sufficiently effective additive incorporation, so that acid soluble progression can occur completely.

(Ii) Formation of an acid-soluble titania matrix includes partial sources of TiO ₂ to Ti ₃ O ₅ . The formation of products with the homogeneous reduction required from the most useful natural titanium iron ores requires a relatively long residence time at high temperatures.

(Iii) The high temperatures and residence times actually required for the homogeneity of the distribution of oxygen and additives in the acid-soluble titania matrix, as opposed to those described in the prior art, result in undesirable deposits in existing devices that continue to process most natural ores. Get the result. This phenomenon is observed irrespective of the execution of the pre-oxidized lasting.

(Iii) Under conditions necessary for efficient reduction, large amounts of titanium, iron nitride and carbides are formed. At this stage, the efficiency of iron removal is reduced and the titanium solubility is significantly reduced.

(Iii) It has been observed that the removal of ferrous metals (for synthetic rutile synthesis) cannot always be effectively applied for iron removal from matrices made of acid-soluble tatania in the water-soluble aeration process according to the method described above in the prior art.

(Iii) For many titanium iron ore, free or unfree gangue or impurity grains (phosphorus, chromite, etc.) that cannot be easily removed from the source ore leads to product grades without a suitable source for the production of sulfate pigments. .

The need for the practice of oxidative roasting of ores according to the prior art is a significant problem in the actual process of acid soluble titania because it involves an additional high temperature treatment step. Another problem is the mentioned conditions of the addition of magnesite, which increases the cost and has a substantial effect on the final product grade.

It is an object of the present invention to provide an industrially useful process for the production of acid soluble titania.

Accordingly, the present invention provides a method for producing acid-soluble titania, which is composed of the following steps.

(Iii) If the ore does not contain enough manganese and magnesium to satisfy the following relationship, add manganese or magnesium to the titanium iron ore,

a is the weight% of MgO contained in the ore, b is the weight% of MnO contained in the ore, and d is the weight% of TiO ₂ contained in the ore.

(Ii) heating the titanite in the presence of a reducing agent for a temperature and for a time sufficient that the contained iron is reduced to its metal form and the contained titania is converted to an acid-soluble form without severe adhesion of the ore; After cooling the product of step (ii) (i) the product of step (i) is water soluble chemically treated to substantially remove iron from the ore.

At this time, the manganese and magnesium compounds may be oxides or decompose into oxides under reaction conditions.

Preferred embodiments of the invention are as follows.

(Iii) Titanium-containing ores (ilmenite, lococene, anatees and rutile, etc.) are optionally mixed with small amounts of additives to ensure a uniform distribution of the input. Fine titanium ore (eg 100% through a 100 μm cracked screen) can be mixed without grinding. Most titanium-containing ores (eg those found in beach sand) would be advantageous to grind during mixing to provide sufficient ore surface area for a suitable ore / additive reaction or the next step.

(Ii) The ore is then optionally aggregated using the techniques detailed in International Patent Application No. PCT / AU89 / 00314 to obtain agglomerated products suitable for the next treatment without excessive dusting.

(Iii) the resulting milled or agglomerated ore is reduced by heating to a temperature sufficient for a sufficient time for the iron contained in the presence of carbon or other suitable reducing agent to be essentially converted to a solid metal and the titania contained in an acid soluble form Let's do it.

(Iii) The reduced ore is cooled to near room temperature and then subjected to a water soluble chemical treatment such as leaching or aeration to substantially remove the metallic iron contained. For example, the agglomerates may be ground prior to water solubilization to sufficiently liberate unmetalized gangue grains for separation by magnetic separation. The upgraded acid-soluble titania product obtained is washed and dried.

(Iii) In general, the removal of metallic iron will degrade the aggregates while releasing the intrinsic gangue impurities. These impurities can be removed in several ways that are not efficient or convenient in advance.

The titania product may contain greater than 90% TiO ₂ (based on the included titanium), which is generally highly soluble in sulfate acid and generally contains titania when producing sulfate pigments over slag products containing only less than 85% TiO _2. High reproducibility. The nature of the product will depend on the particular source used.

Improvements over the prior art with respect to the present invention which form expensive acid-soluble products from natural titanium iron ore under industrially feasible conditions are as follows.

(Iii) In the present invention, there is no need for oxidation roasting treatment for incorporation of additives and there is no need for preventing deposit formation.

(Ii) In the present invention, there is no need to carry out a reduction step at a temperature above 1200 ° C., and consequently, adhesion and formation of carbides and nitrides can be avoided.

(Iii) It is not necessary in the present invention to include additives for all sources. An improvement in connection with the present invention is to obtain the maximum benefit that can be obtained from the composition of the ore received. Optional additives to magnesium compounds have also been defined as part of the present invention.

(Iii) The conditions under which the removal of metal iron from the ore product reduced by the aqueous solubility treatment without the formation of iron oxides in the titanium-containing grains are carried out effectively are specified.

In addition, the form of the separated iron oxide product formed (eg magnetite or hydrated ferric oxide) can be adjusted to expand the ore / iron oxide separation and provide iron oxide byproducts of consistent nature.

(Iii) Separation of the original gangue and the contents ore can be carried out after reduction and removal of the metal iron. This represents a particular advantage when this separation is not easily obtained with the ore accepted.

A process flow diagram illustrating a preferred embodiment of the present invention is shown in FIG. The process flow chart consists of a (optional) crushing step, an optional mixing / aggregation step, a heat reduction and cooling step, and an iron metal removal step, and any ore separation can come next to iron removal.

Particularly preferred steps are agglomeration before the heating step if finely ground metals are to be treated or additives are required. It is advisable to have good ore / additive mixing and contact with a wide ore surface area for the efficient homogeneous incorporation of additives and the homogeneous reduction of titania without the need for excessive residual time and high temperatures in the reduction or without preliminary oxidation roasting steps. This is because the reduction and dispersion of the additive to the titania matrix takes place from outside of the grain to the inside. As a result, the fine ore size obtained by grinding increases the reduction and homogenization ratio.

In practice it is not possible to obtain the desired product from the fine ore particles through reduction of the titanium iron ore because the relative gas / ore rates cause excessive dusting loss of the ore, making it difficult to contain fine ores in the reduction system. This is especially the case when relatively high temperatures (eg above 1100 ° C.) and long residence times (eg above 30 minutes) are required for the reduction of fine ores.

The present invention can be used in a finely pulverized form (typically passing 100% through a 100 μm gap screen, 95% thicker than a 5 μm diameter). The flocculates in the flocculation performed subsequently can be treated in the reduction system of the present invention. Most naturally occurring titanium iron ore needs to be milled using suitable techniques prior to the flocculation step. Titania products obtained from ore sources smaller than 20 μm in diameter are not easily separated from the fine iron oxide product in subsequent processing, so that the ore breaks down to 20 μm fragments during the grinding step. The weight average particle size of the milled product is ideally between 50 μm and 100 μm.

The agglomeration step generally involves adding the binder to a fine ore source containing moisture (eg 5-12% moisture) in a suitable flocculation machine. Briquetting or other suitable techniques may also be applied but it is preferred to use a cohesive aggregate in the form of low strength discs or drums or high strength mixing. A suitable class of flocculation techniques is described in International Patent Application No. PVC / AU89 / 00314. Although only a small amount of agglomerated product passes through the 50 μm gap screen and agglomerates with a particle size of less than 4 mm are preferred for easier handling in the next step of the present invention, there is little limitation on the agglomerate size. Narrow particle size distribution is not required.

Where it is advantageous to include additives and ore sources, the additives may be incorporated in the flocculation step or in the grinding step. Dispersion of the additives in the aggregates is also advantageous. The additive may be included with the water supply material in the flocculation step in powder form, slurry form or solution. Optionally, manganese compounds may be used for certain purposes under any circumstances.

In the flocculation step, any organic or inorganic binder may be used as appropriate. In many cases, a mixture of sodium silicate, bentonite and inorganic binders such as clay minerals, magnesium salts, lime and soda and organic binders such as lignosulfonate, PVA and molasses is preferred. Self-hydrolysing binders such as tetraethylorthosilicate, aluminum sulfate / urea mixtures are also known to be effective. The binder is suitably added in the range of 0.5 to 5.0% with respect to water. In the case of the inorganic binder, it is preferable to limit the addition of the binder to less than 1% with respect to water.

In some cases, it is preferable to carry out two separate grinding and flocculation steps. If two ores that require different compositions and different additives are handled, the flocculation step can be carried out separately. In this way the additives are bound to the site of maximum efficiency to obtain a high quality product using a small amount of additives.

In particular, it is desirable to prepare aggregates having open structures and nearly occluded pores. In this way the surface useful for additive reduction and interdiffusion will be slightly smaller than the ore surface prior to flocculation. It must be avoided to produce dense aggregates that are shrunk and thermally sintered by heat. The preferred open structure can be easily obtained when the aggregated ore contains only a small amount of material having a particle size of 20 mu m or less, and the average size of the aggregate is less than 1 mm even when the particle size is large.

The addition step can be carried out between the grinding step and the flocculation step, for example, in the grinding, grains containing gangue or impurities are produced. Separation may be carried out on the basis of the separation step, in particular particle size and density, magnetic reaction or electrostatic reaction or surface action or combination of such actions. If desired, advantageously high quality ore can be dried before flocculation using an appropriate drying apparatus.

Reduction can be carried out with a suitable device, such as a packed bed, fluidized bed or circulating fluidized bed reactor. The most suitable device for continuous and high temperature reduction over 30 minutes with metallization is the use of coal or coke as fuel and reducing agent. It is an inclined rotary furnace. Rotary furnaces for the reduction of iron ore and ilmenite metallization in the production of synthetic rutile have been used for almost 20 years and their use is well known.

The method of use of the furnace of the present invention is similar to the use of the furnace to produce synthetic rutile.

The process of the invention can be carried out at high temperatures without the formation of deposits. This is particularly possible in the case of agglomerates due to the nature of the agglomerates which absorb liquid substances such as liquid iron, silicates or oxides resulting from reduction or partial oxidation at high temperatures. The liquids are retained in the meniscus created between the solid surfaces in the open aggregate structure. As a result, the liquid material cannot act as a bridge for each aggregate, so the formation of deposits is minimized but not removed.

According to the present invention it is not necessary to carry out the reduction step at a maximum temperature of 1200 ° C. or higher in order to produce an acid soluble titania matrix of suitable properties in titanium ore. Most materials can use temperatures around 1130 ° C. Despite the use of highly reducing conditions, nitrides and carbides are produced to a minimum at relatively low maximum temperatures in the reduction. According to the present invention numerous carbonaceous reducing agents ranging from lignite to sub-bituminous coal or coke powder and coke powdered coal can be used as suitable reducing agents. The gaseous reducing agent can be used in a fixed fluidized bed process, preferably using carbonaceous heat source reduction in a rotary furnace. If a less active carbon source such as coke is used, a higher proportion of carbon will be used for the ore. Highly active carbon sources such as lignite and lignite char can produce acid soluble titania at low temperatures.

When the reduction is carried out in a rotary furnace, a kiln temperature profile slightly different from that used for the production of synthetic rutile or directly reduced iron is not necessary but preferably used. It is possible to maintain the temperature of the reducing zone of the kiln layer to complete the iron metallization reaction by adjusting the gas injection position of the kiln exhaust tip burner and kiln gun gas fire extinguishing. The reduction of titania can be completed in a short region causing an increase in bed temperature near the outlet end of the kiln. As a result, the reaction is completed under essential high temperature conditions (about 1170 ° C.), while the charge maintains most of its reduction time at a significantly lower temperature (1130 ° C.). This action can also minimize deposits.

For many ores, especially magnesium and manganese-rich ores in titania ores, it is not necessary to use additives in the aggregated ore to produce acid soluble titania during the reduction reaction. The action of producing a suitable product without additives is a direct advantage provided by flocculation by promoting the reduction step and reducing the tendency of deposit formation.

Some indicators necessary for the addition of additives are known. In particular, the titania content of the reduced titania matrix is a single phase represented by the general formula M ₃ O ₅ consisting of a solid solution of Ti ₃ O ₅ , MgTi ₂ O ₅ , Al ₂ TiO ₅ , FeTi ₂ O ₅ , MnTi ₂ O ₅ It is thought to occupy most of the inside. The presence of sufficient diluents (particularly magnesium and manganese) to inhibit the following types of reactions that produce acid insoluble reduced rutile is important for producing high quality acid soluble titania;

6Ti ₃ O ₅ + FeTi ₂ O ₅ = 5Ti ₄ O ₇ + Fe

8Ti ₃ O ₅ + 3FeTi ₂ O ₅ = 5Ti ₆ O ₁₁ + 3Fe

In general, the appropriate addition of additives can be represented by the following relationship between the oxide content in the titania end product.

Wherein a, b and d are as described above.

If the additive is used in a smaller amount than suggested in the above formula, the difficulty of use can be avoided if the indicated limit of oxide is allowed. For ilmenite the relationship does not require the addition of additives at all. Additives can be used to remove impurities after the reduction step. In particular, it was found that the metallization of chromite was promoted by adding manganese to the aggregate and removing chromium from the acid-soluble titania product by magnetic separation after the aqueous mixing process in which the magnetic ferro chromium alloy remained in a passive state. . The separation method based on the metallization of chromite is in accordance with PCT / AU89 / 00461.

After reduction, the reduced ore and excess char is preferably cooled using a rotary drum cooler or other suitable device. The char can be separated from the ore using sizing and magnetic separation. When the ore agglomerates before reduction, the reduced agglomerates are broken to separate unmetalized gangue while improving quality by magnetic separation.

It is an object of the present invention to improve conventional methods of removing metal iron from reduced ores. Conventional aqueous aeration to remove metal iron was only used to remove iron from the acid insoluble titania matrix. It has been found that conventional methods are not always effective at removing metal iron from acid soluble matrices without self precipitation of contaminating iron oxides in titania ores. In particular, this difficulty was observed when the desired iron oxide product for later separation purposes was granular magnetite.

The reason why the conventional aqueous aeration process is inefficient in removing iron from the acid soluble matrix is related to the high sintering rate of the acid soluble phase in reduction and the different distribution of the metal iron in the titania matrix. The real effect of this difference is that metal iron is not easy to remove which promotes oxidation and precipitation of iron in titania grains.

The properties of separable iron oxides were adjusted to improve the definition of the conditions necessary for the effective removal of iron from acid soluble titania matrices. In particular, based on this improvement, certain reagents have been defined that are effective for promoting iron removal by aqueous aeration.

The aqueous aeration chamber of the present invention comprises a stirred suspension of metal soluble titania that is metallized in a reagent solution prepared by a particular method of injecting finely ground air bubbles. Preferably, the aqueous aeration is carried out in the range of 60 ° C. to 80 ° C. for 8 to 24 hours.

This improved process consists of adding a reagent to the aeration step to form a complex with iron to stabilize iron in aqueous solutions, and also at high iron oxide potentials, for example from grains containing metals. It is produced only in remote areas and has a partial pH buffering effect. The reagents also act ideally to stabilize certain iron oxides (eg magnetite, macromagnets, lepidocrocite or goethite, etc.). It has also been found that, despite the prior art associated with the use of alkali salts, the addition of alkali salts should be avoided because they react with iron oxides to promote their own iron oxide production.

In particular, an aqueous system provided for chelation or complexing of iron has the effect of stabilizing iron temporarily in the aqueous solution to be observed, which is very effective as an aeration system around titanate grains. However, the stability of iron in solution will not inhibit precipitation to iron oxides under strong oxidizing conditions present in common aeration solutions. The strong stability of iron in solution will consume complexing agents and cause a sharp rise in pH. Eventually, the movement of iron out of the titanate grains is delayed and iron oxides settle in place. The nature and amount of additives in the aeration step is important for effective aeration. In particular, the range of useful amounts of addition depends on the nature of the reduced titania, depending on the reduction process such as the rate of reduction and the duration at constant temperature.

In particular, citric acid is preferred as an additive to aid in the aeration of reduced titania ores. It is preferable to add in the range of 0.06 to 0.1 weight% with respect to the aeration solution. Citric acid may be added on its own or in combination with other aeration chemicals such as ammonium chloride as described above. It is effective to add iron chlorides such as iron chloride at high concentrations (5% of iron chloride). Many other systems are expected to be similarly effective in ways not previously anticipated.

Appropriately reduced aggregates can be broken down into subgrains that are generally equivalent to titanium ore. This action is due to the propensity of metal iron to form bonds between gemstones in the reduction of aggregates produced by the method described above. Removal of the binding iron in these granules results in the breakdown of aggregates.

Degradation of the aggregates during aeration may remove the free gangue or grains containing impurities after aeration in a suitable manner. First, iron oxides were removed from the titanium particles in the aeration by wet cycloning, separation by weight, wet screening or other effective methods. Next, the separation of the non-titanium grains, for example, by flotation, magnetic separation, electrostatic separation, or neutralization, can be used for high quality of the final material. This quality step is particularly useful for impurity grains of similar nature to the source nature of the process prior to the treatment described, although there are differences in the nature of the product grains, for example, the source is contaminated with chromite.

A feature of the acid soluble titania produced by the process of the present invention is that small amounts of metal iron in amounts of 0.1 to 2% by weight remain inaccessible to aeration or acid leaching. Residual metal iron is distributed in metal particles of less than 3 μm in diameter protected entirely by concentrated acid soluble titania. The residual metal iron does not interfere with the removal of high magnetic materials and magnetic field components at low magnetic field strengths, but causes effective magnetic separation of the product from nonmagnetic impurities such as quartz and gangue silicates.

As an optional final step of the present invention, the titanium product washed with dilute acid, such as 5-20% sulfuric acid, may have the effect of improving the product quality (and a small amount of iron) by the removal of residual iron oxides.

The acid soluble titania production method of the present invention is present in the titanate ore as particulate phosphoric acid removed in the separation step or as phosphorus (removed by separation with iron oxide or leaching solvent after leaching) during reduction and aeration with metal iron. In either case, phosphate impurities have the advantage of being removed.

In addition, it was found that the chromite grains remaining in the titanium product by the method of the present invention may not be dissolved in the acid dissolution of the titania containing. Chromite is stable to acid dissolution during the heat reduction reaction in the presence of ilmenite. This fact is of great concern with the usefulness of the product in the sulfuric acid method for pigment production.

EXAMPLE

The following examples show a number of measurements suitable to represent the methods described herein.

Example 1

In this example, 300 g of fine crystalline ilmenite of 55 μm average particle size components provided in Table 1 were mixed with 150 g of Victorian brown coal char (-4 mm + 0.5 mm) and placed into a stainless steel furnace. On top of this mixture was placed a 10 mm layer of char and the crucible was placed in a heated muffle. After 75 minutes, the dose reaching the maximum temperature of 1180 ° C. was held in the furnace for 120 minutes further before the crucible was removed and allowed for air cooling.

The coarse char was separated from the reduced product by size through a 200 μm screen and separated from the reduced product by magnetic separation to provide a separated metallized ilmenite product.

Chemical analysis showed that 94.1% was fully metallized. X-ray diffraction analysis showed that substantially total contained titania is present as enosobite, free of rutile, reduced rutile or nitride / carbide.

Impurity separation after reduction and charcoal separation was determined by magnetic separation of subsamples of nonmagnetic removal, using laboratory Kafko lift-type magnetic separation. At this stage 44% of chromium could be removed with non-magnetic chromium and only 10% of titania contained could be achieved. This will result in an initial addition of 2 ml of 10% H ₂ SO ₄ and air at 0.5 liters per minute to achieve metallic iron removal and aeration of the reduced product for 16 hours in 1.8 liters of 0.5% NH ₄ Cl solution at 80 ° C. There was a need.

The iron oxide formed during the aeration was mainly black magnetite, as confirmed by the X-ray diffraction method.

After removal of the separable iron oxide by 38 μm screening, the aeration product contained a total amount of 0.3% iron and 6.3% iron present as metals. The titanium content of the product was 84.8% of dioxide.

In a Kafko lift-type magnetic separator, the magnetic content was added to 0.32% Cr ₂ O ₃ to remove 72% of the contained chromium (chromite), 37% of the alumina contained and 48% of the silica contained. It was performed to discharge 86.9% TiO ₂ non-magnetic product. The resulting acid solubility was measured in 71% sulfuric acid refluxing for 15 minutes. Unseparated aeration product was 91.6% such as 88.5% solubility, titania solubility.

Example 2

In this example, 5 g of the 55 μm average particle size microcrystalline silicate titanite of the components provided in Table 2 were mixed with 7.5% by weight of finely divided magnesite and placed in a molybdenum crucible boat. This mixture was heated and reduced in a duct furnace under a stream of mixed CO ₂ / H ₂ gas which gave an equilibrium oxygen fugity of ^10-16 atm for 4 hours at 1200 ° C. Reducing conditions were taken as simulating conditions into the direct reduction furnace. At the end of this equilibrium sample was quenched with recovery at the end of the water cooled brass crucible. X-ray diffraction revealed that titania is present only in trace amounts of the reduced rutile Ti ₄ O ₇ remaining mainly after the treatment, mainly in the enosome bite. The acid solubility of titania in the reduced product was found to be 86.2%, measured in the same manner as in Example 1.

Example 3

Example 3 was treated in the same manner as in Example 2 except that it was prepared by adding 7.5% MnO ₂ instead of magnesite addition. The acid solubility of titania in the reduced product was determined to be 97.4% in this case. A logical study for the high efficiency of manganese addition in promoted acid solubility compared to magnesium addition (Example 2) showed that magnesium did not contribute to the product as a whole, whereas manganese contributed homogeneously. Penetration of magnesium into the titanate particles was aided by the microcrystalline nature of titania, but was limited by diffusion into the grains via solid titania substrates. Manganese was able to transfer quickly in the case of vapor phase diffusion.

Example 4

Ilmenite with the components provided in Table 3 were ground and sized in the range -106 + 53 μm. A sample of 400 g of foreign material was mixed with 7.9 g of finely divided magnesite and 200 g of -44 mm + 1.4 mm brown coal char and reduced, separated and aerated, as summarized in Example 1 except that the diamagnetic separation was carried out. Placed into a stainless steel furnace for the same treatment. After 24 hours, slowly incomplete aeration formed a black magnetite. The aeration product contained at the iron oxide site contained a total amount of 6.2% iron and 9.7% iron present as metals. The titanium content of the product was found to be 73.9% in terms of dioxide. The titania solubility according to the measurement described in Example 1 was 90.3%.

Example 5

In this example, reduced ilmenite (average particle size 55 μm) became the first agglomeration by addition of 3% lignosulfonate, 0.7% bentonite and 10% moisture in a laboratory Patterson-Cali flocculator. The -2 mm + 0.25 mm aggregated product was dried for the next reduction. The coagulation component is shown in Table 4. Agglomeration amount of 400 g was mixed with the top layer of charcoal according to Example 1 and 200 g of -4 mm + 1.4 mm Victorian Brown coal charcoal. The reduction was then carried out at 1180 ° C. of Example 1. After reduction and separation of the char from the cooled and reduced agglomerates, they were carefully ground by closed rotation with a 90 μm aperture screen falling into the 38 to 90 μm particle size range. Magnetic content was then used to remove 4.9% of the material relative to the nonmagnetic portion, which originally contained 29% of chromium, resulting in a magnetic product containing 0.44% Cr ₂ O ₃ . The aeration of the reduced, isolated product was treated with a 200 g sample of reduced ore added at 80 ° C. for 6.5 hours in 1.8 L, 0.5 L / min air addition of 0.8% ammonium chloride and 0.2% citric acid solution. The iron oxide formed by aeration was red / brown lepidocrocite. After removal of the separable iron oxide by 38 μm screening, the aeration product contained a total amount of 0.5% and 6.5% iron present as metals. The titanium content of the product was 86.1% of dioxide. Magnetic separation in a Kafko lift-type magnetic separator was carried out to remove 61% of chromium, 31% of alumina, 24% of silica and 37.% of phosphorus contained for magnetic components, and 0.33% Cr ₂ O. ₃ discharged the non-magnetic product 88.9% TiO ₂ . The acid solubility of the product was measured as in Example 1 without further grinding. The acid solubility of the product was measured as in Example 1 without further grinding. Titania in the product was analyzed to be 88.1% solubility. The final phosphorus content was 0.09% P ₂ O ₅ compared to the ilmenite source phosphorus content of 0.46% P ₂ O ₅ .

Example 6

In this example, 300 g of 55 micron average grain size fine hardening ilmenite provided in Table 5 was mixed with 150 g of Victorian brown coal charcoal (-4 mm + 1.4 mm), and reduction was carried out in the same manner as described in Example 1. To a stainless steel furnace.

After reduction, the magnetic content of the ore removed 25.0% of the chromium contained as nonmagnetic chromite particles. The reduced and isolated product was subjected to aqueous aeration in a 1.8 liter, 0.26% citric acid solution of 0.2% NH ₂ Cl for 6.5 hours at 80 ° C. The iron oxide formed was separated by screening in a small size at a screen diameter of 38 μm, and was found to form red / brown lipidocrosite. The +38 μm ore contained the total amount of 0.03% iron and 4.2% iron present as metals. The titanium content of the product was found to be 88.8% of dioxide.

The magnetic powder was treated with a +38 μm aerator to remove 29.8% of chromium (chromite), 13.9% of alumina and 9.9% of silica contained in the magnetic portion, and 0.61% Cr _2. The nonmagnetic product 90.2% TiO ₂ was discharged from O ₃ .

The final phosphorus content was 0.19% P ₂ O ₅ with respect to the phosphorus content of the source of 0.46% P ₂ O ₅ .

Example 7

Aqueous aeration was performed at 1.8 liters of 1.0% NH ₄ Cl, 0.7% citric acid and 0.3% triammonium citrate. After 24 hours of aeration, the aerator solid sample with incomplete ferrous metal removal further released hydrogen when exposed to 5% aqueous hydrochloric acid. In addition, the iron oxide generated in the aeration was a noticeable brown amorphous material that was not readily precipitated and could not be removed from the +38 μm product.

This resulted in the formation of iron oxide below the titanate particles as a +38 μm product containing continuous evidence of iron present as metal and a total amount of 6.3% iron. The titer content of the product was found to be only 82.0% of dioxide.

Example 8

In this example, aggregates in the particle size range ranging from -4 mm to 0.25 mm were dried in a tumble dryer by mixing with 3% lignosulfonate, 0.7% bentonite and 7% moisture, followed by the ilmenite of the components given in Table 6. Formed from.

These agglomerates were fed into a 5 mm long, 0.4 m internal diameter rotary furnace from 5 kg / hour to 13 kg / hour of -5 mm + 0.5 mm Victorian Brown coal charcoal. The temperature contribution from the furnace was controlled by the use of discharge end burners, and the air injection lance was introduced into the furnace gas space from the feed end in order to achieve a temperature of 2.5m length of the final furnace over 1100 ℃ and 0.5m length of the final furnace of 1135 ℃ Inserted. The furnace release was cooled on the Archimedes screw before collection. The cooled release was magnetically separated from the char and analyzed by x-ray diffraction for the presence of insoluble rutile and reduced rutile. It has been completely converted to enosobit. After the removal of metallic iron by leaching with 5% sulfuric acid, the ore product showed the same 90.3% titania solubility as 85% solubility according to the measurement described previously.

Analysis of the residues of the acid solubility measurements of the acid soluble titania products prepared by the methods of Examples 5 and 6 showed that chromium was present in the titania particles and the solubility in the measurements performed with 71% sulfuric acid was 0.2% Cr ₂ O ₃ The following amounts were found. Chromium contained in the chromite particles was consistently found to be insoluble in both measurements performed with 71% sulfuric acid and 91% sulfuric acid. The comparability measurement by 92% sulfuric acid was dissolved in 22% of the source lemite of chromium contained in chromite.

Chromium, present as chromite particles, was thus provided as an inert solution in sulfuric acid by the high temperature reduction method. Particle analysis using electron microtechnology has been shown to substantially rearrange iron with chromium by manganese originally present in ilmenite.

Substantial changes in chromite have been effectively provided for inert acid dissolution. The advantage is that agglomeration is possible for homogeneity of addition and reduction of additives, and the formation of acid soluble titania from the titanium source stock at relatively low reduction temperatures indicated in Examples 2, 3, 4, and 8, which are not illustrated in the prior art. Allowed. The comparative insufficiency of the electrostatic aeration run (using ammonium chloride additive) in the formation of acid soluble titania is illustrated by comparison of the effect of aeration, the term of acid required for demolition agents in Examples 1 and 4 and Examples 5 and 6 It became. The effect of the composites during quenching aeration is illustrated in Examples 5 and 6, and the limiting substance to the addition of the composites is shown in Example 7 compared to Example 6. In addition, the modifying properties of the iron oxide product formed in the aeration with the use of chemical additives are illustrated in Examples 1, 4, 5, 6 and 7.

Example 3 confirmed an effective manganese addition by promoting the formation of an acid soluble phase by the same or superior method of magnesium shown in the prior art. The efficacy of separation before and after formation of aeration to remove chromium and phosphorus is illustrated in Examples 5 and 6.

The ability to substantially produce acid soluble titania product at a relatively low reduction temperature in a rotary furnace without effective deposition formation in accordance with the principles presented herein is illustrated in Example 8.

The above-mentioned details will make the understanding clear without limiting the general purpose of the present invention.

Claims (18)

(Iii) adding a manganese compound or magnesium compound, if necessary, to the titanium iron ore, which is an oxide or can be decomposed into an oxide under reaction conditions, so that the titanium iron ore sufficiently contains manganese and magnesium to satisfy the following formula; Where a is the weight% of MgO contained in the titanium iron ore, b is the weight% of MnO contained in the titanium iron ore, and d is the weight% of TiO ₂ contained in the titanium iron ore. (Ii) heating the titanium iron ore at a constant temperature for a sufficient time in the presence of a reducing agent to reduce the iron contained therein into a metal form, and converting the titania contained therein into an acid-soluble form with little adhesion of the titanium iron ore. Acid, which comprises (i) cooling the product obtained in step (ii), and (iii) substantially chemically removing iron from the titanium iron ore by aqueous chemical treatment of the product of step (iii). Method for preparing soluble titania. The method of claim 1, wherein the temperature for heating the titanium iron ore is in the range of 1130 to 1200 ° C. The method of claim 1, wherein the manganese compound is added in the form of manganese dioxide. The method of claim 1 wherein the magnesium compound is magnesite or magnesium carbonate. The method of claim 1, wherein the titanium iron ore is agglomerated before heating and pulverized prior to agglomeration when the particle size of the titanium iron ore exceeds 100 microns. The method of claim 1, wherein the aqueous chemical treatment is performed in the presence of a metal ion sequestrant capable of sequestering iron in an aqueous solution to buffer a local pH, the iron oxide is a high oxidation potential in a portion away from the metal-containing particles How to get formed. The method of claim 6, wherein the aqueous solution contains 0.06 to 1% by weight of a metal ion sequestrant. The method of claim 6, wherein the metal ion sequestrant is citric acid. The process according to claim 1, wherein the product of step (iii) is washed with dilute acid having a concentration of 5 to 20% by weight. The method of claim 9, wherein said acid is sulfuric acid. The method of claim 1 wherein the reducing agent is selected from the group consisting of coal, coke, charcoal, brown charcoal and dense lignite. The method of claim 1, wherein the product of step (iv) is subjected to magnetic beneficiation to extract the nonmagnetic portion as a product, and the magnetic part proceeds to step (iv). 13. The method of claim 12, wherein the product of step (iii) is subjected to a magnetic beneficiation step. 2. The inclined rotary furnace of claim 1, wherein the step (ii) comprises a discharge end burner and an air injection device positioned along the rotary furnace such that the rotary furnace has a relatively short completion zone adjacent to the reduction zone and the discharge end of the rotary furnace. Wherein the reduction zone has a temperature that is kept relatively constant and the completion zone has a temperature that rises toward the discharge line of the rotary furnace. The method of claim 14, wherein the temperature of the reduction zone is about 1130 ° C. and the temperature in the completion zone reaches about 1170 ° C. 16. An acid-soluble titania made according to the method of any one of claims 1 to 15. An acid-soluble titania containing an acid-insoluble chromite ore impurity prepared according to the method of any one of claims 1 to 15. An acid soluble titania containing an acid soluble titania prepared according to the method of any one of claims 1 to 15, wherein the phosphorus is a contaminant in the titanium iron ore.