NL2003597C2

NL2003597C2 - TITANIUM CONTAINING ADDITIVE AND METHOD FOR ITS MANUFACTURE FROM CHLORIDE CONTAINING RESIDUES FROM TITANIUM DIOXIDE PRODUCTION.

Info

Publication number: NL2003597C2
Application number: NL2003597A
Authority: NL
Inventors: Wilhelm Eitel
Original assignee: Kronos International
Priority date: 2008-11-11
Filing date: 2009-10-06
Publication date: 2010-11-24
Also published as: DE102008056809A1; FR2938256A1; NL2003597A

Description

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Titanium-containing additive and method for its manufacture from chloride-containing residues from titanium dioxide production

Field of the invention

The invention relates to a titanium-containing additive for feeding into a furnace to increase the durability of the refractory lining, a method for its manufacture, 10 and its use.

Technological background of the invention 15 The use of titanium-containing additives in furnaces (high-temperature facilities) with a refractory lining for smelting reduction processes, particularly in blast furnaces, has been familiar for a long time. In this context, the effect of titanium-containing additives is based on the formation of high-temperature-resistant and wear-resistant Ti(C,N) compounds, which are partly deposited on the inner walls 20 of the refractory lining of the furnaces, particularly in the hearth of blast furnaces, and increase the durability of the lining.

The titanium-containing additive customarily used is lump ilmenite, as a natural titanium carrier. Furthermore, the use of residues from titanium dioxide 25 production as a titanium-containing additive is also known.

EP 0 611 740 B1 describes a titanium-containing additive consisting of digestion residues from titanium dioxide production by the sulphate process, together with materials containing coal and/or iron. According to EP 0 686 700 Bl, additives 30 containing alkaline earths, aluminium and/or S1O2 are likewise used, as a result of which the additive can also act as a slag-forming agent.

DE 10 2007 055 751 A1 discloses a moulded body containing titanium that can 2 similarly be used as an additive for increasing the durability of refractory systems, and as a slag protection and alloying agent, and that contains natural and, where appropriate, also synthetic titanium carriers. The term "natural titanium carriers" is taken to mean titanium ores and Sorel slags. The term 5 "synthetic titanium carriers" is taken to mean, inter alia, residues from titanium dioxide production.

DE 198 30 102 Cl specifically discloses the use of a fine-grained product, occurring during the production of titanium dioxide by the chloride process, for 10 injection into a blast furnace to increase the durability of the refractory lining. The fine-grained product is preferably used in a mixture with components containing iron, alkaline earths and/or aluminium oxide or hydroxide.

15 Object and brief description of the invention

The object of the invention is to put a chloride-containing co-product of titanium dioxide production to commercial use.

20 The object is solved by a titanium-containing additive for feeding into a furnace to increase the durability of the refractory lining, characterised in that it contains chloride-containing residues from titanium dioxide production, to which has been admixed at least one substance from the group comprising alkali hydroxide, alkali carbonate, alkali hydrogencarbonate and alkaline earth carbonate.

25 The object is further solved by a method for manufacturing a titanium-containing additive, characterised in that chloride-containing residues from titanium dioxide production are mixed with at least one substance from the group comprising alkali hydroxide, alkali carbonate, alkali hydrogencarbonate and alkaline earth carbonate in at least stoichiometric quantities in reference to chloride.

Further advantageous embodiments of the invention are described in the subclaims.

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Description of the invention 5 In the chloride process for manufacturing titanium dioxide, titanium tetrachloride is produced in a first step by chlorinating titanium-containing raw materials. Chlorination is performed in a fluidised-bed reactor in the presence of coke at temperatures in the region of 1,000 °C, and leads to the formation of volatile metal chlorides. When discharging the metal chlorides from the reactor, 10 fine bed material is also entrained, particularly unreacted titanium-containing raw material (T1O2), further inert metal oxides from the raw material (particularly S1O2) and coke. This gas/solid mixture is cooled to approx. 150 °C. The solid component is separated out in a cyclone. The fine-grained mixture of solids obtained in this way is customarily also referred to as cyclone dust.

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The cyclone dust is subsequently washed and, after drying, contains roughly 40 to 60% by weight coke, roughly 25 to 45% by weight Ti02 and roughly 5 to 15% by weight S1O2 as its principal constituents. The moisture content is usually roughly 20 to 35% by weight, and the chloride content is up to roughly 1% by weight. The 20 material obtained in this way, referred to as "chloride-containing residue" below, reacts acid and has a highly corrosive effect.

Because of its acid character, further processing of the chloride-containing residue is thus problematic, since materials used in machinery, such as steel, 25 high-grade steel, non-ferrous metals and aluminium, are exposed to substantial corrosive attack and the machines are damaged as a result. Moreover, there are health risks for the affected personnel, and possibly also environmental risks.

According to the invention, the chloride-containing residue is therefore mixed 30 with at least one substance from the group comprising alkali hydroxide, alkali carbonate, alkali hydrogencarbonate and alkaline earth carbonate. Mixtures of these substances can also be used. The alkalis involved are, for example, Na and 4 K. The alkaline earths are preferably Ca and Mg.

The chloride-containing residue treated in this way reacts neutral and is suitable for use as a titanium-containing additive in industrial smelting reduction 5 processes to increase the durability of the refractory lining in furnaces. Within the framework of the invention, "furnaces" is taken to mean all kinds of high-temperature facilities with a refractory lining. The titanium-containing additive according to the invention can be used directly or first subjected to further processing, without incurring high tool costs as a result of corrosion.

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The neutralising agent is added in at least stoichiometric quantities referred to the chloride content, i.e. in quantities of roughly 0.5 to 50 kg per metric ton chloride-containing residue. Neutralisation produces the corresponding alkali chlorides, such as sodium chloride or potassium chloride, and alkaline earth 15 chlorides, such as calcium chloride or magnesium chloride. If carbonate compounds are added, the carbonate component escapes in the form of CO2. The alkali content in the titanium-containing additive according to the invention is not detrimental to use in furnaces with a refractory lining.

20 Neutralisation is preferably performed in an inert-lined mixer, e.g. in a rubber-lined mixer, particularly in a continuous mixer. The chloride-containing residue neutralised in this way can be further processed, e.g. pelletised or briquetted, in moist condition and subsequently dried. Alternatively, the neutralised chloride-containing residue can be dried directly to obtain a powdery product.

25 In a further embodiment of the invention, the neutralised chloride-containing residue can be mixed with further additives in an intermediate step, e.g. with a binder such as cement, filter ash, bitumen, etc. In another embodiment of the method, at least one slag-forming agent can additionally be admixed, such as alkaline-earth, aluminium or silicon oxide.

The neutralised chloride-containing residue is suitable as a titanium-containing additive for use in furnaces with a refractory lining to increase the durability of 30 5 the refractory lining. It can be injected into the furnace in powdery form with a particle size of less than roughly 5 mm, or introduced into the furnace in agglomerated form (as granules, pellets, briquettes, etc.) with particle sizes of greater than roughly 5 mm.

5 Moreover, the titanium-containing additive is also suitable for use as an energy carrier and sintering aid in the ceramic and clay industry.

Examples 10

The invention is explained on the basis of the following examples, which are not intended as a limitation of the invention.

Example 1 15 1 kg of a moist cyclone dust with a chloride content of roughly 0.5% by weight, obtained from carbochlorination, was pasted up into a 10% by weight aqueous suspension. The pH value was 2.9. 5.8 g NaOH were admixed in the form of a 0.1 molar sodium hydroxide solution (NaOH). A pH value of 7 was subsequently 20 obtained.

Example 2 1 kg of a moist cyclone dust with a chloride content of roughly 0.5% by weight, 25 obtained from carbochlorination, was pasted up into a 10% by weight aqueous suspension. The pH value was 2.9. 13.2 g Na2C03 were admixed in the form of a 0.1 molar Na2COs solution. A pH value of 7 was subsequently obtained.

Example 3

Same as Example 1, the difference being that 8.1 g KOH in the form of a 0.1 molar potassium hydroxide solution (KOH) was used instead of NaOH.

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Claims

Claims 1. Titanium-containing additive for addition to an oven to increase the shelf life of the refractory coating, characterized in that it contains residues from the titanium dioxide preparation containing choloride containing at least one alkali hydroxide compound, alkali carbonate and alkali hydrogen carbonate are mixed.

Titanium-containing aggregate according to claim 1, characterized in that the aggregate is agglomerated to grain sizes of more than 5 mm. 10

3. Process for the preparation of a titanium-containing additive, characterized in that chloride-containing residues from the titanium dioxide preparation are mixed with at least one substance from the group consisting of alkali hydroxide, alkali carbonate, and alkali hydrogen carbonate in at least 15 stoichiometric amount with respect to chloride. .

4. A method according to claim 3, characterized in that the titanium-containing additive is subsequently agglomerated to grain sizes of more than 5 mm,

Method according to claim 4, characterized in that a binder is admixed prior to agglomeration,

6. Process according to claim 3 on 4, characterized in that at least one slag-forming substance such as, for example, alkaline earth metal, aluminum oxide or silicon oxide is admixed before agglomeration.

Use of the titanium-containing additive according to claim 1 or 2 in the melt metallurgical industry. 2003597 30 5

Use of the titanium-containing additive according to claim 1 or 2 in the ceramic and clay industry. 2003597