Abrasive material

p0001abrasive

p0002The invention is directed to a method for making an abrasive material. Furthermore, the invention relates to an abrasive and the use of the obtained Äufschluss of titaniferous raw materials or resulting digestion residue product oriented. Finally, the invention is directed to a Abrasivstrahlschneidverfahren, especially

p0003Waterjet, in which a piece of material processed by a added abrasive containing fluid high-pressure jet.

p0004The abrasivejet, especially the waterjet is a method that has proven itself in practice for years. With waterjet cutting, the material to be processed is processed by a high pressure water jet. This jet has a pressure of up to 6000 bar, which is cut bar for economic reasons, as a rule with a pressure 3200-3800. There are up to 1000 m achieved / s exit velocities. In addition to the pure water cutting or Purwasserschneiden the jet to increase cutting performance is a cutting means, a so-called abrasive often added. By adding such an abrasive, it is possible to cut harder materials, which can not be separated with pure waterjet or their processing with Pure water is not economical. To Abrasive, has a Wasserabrasivstrahlvorrichtung a cutting head having the components pure water focussing tube, abrasive mixing chamber and abrasive focusing tube / focusing tube substantially. It is first of highly compressed pure water jet formed, which in the abrasive mixing chamber the abrasive is added, so that then the water-Abra- sive mixture through an abrasive focusing tube / focusing tube leaves the Wasserabrasivstrahlschneidvorrichtung. The Äbrasivmittel may metered CNC-controlled rule, and the cutting head are supplied either with air as a carrier or in a suspension. When Wasserabrasiv-injector jet a composition of about 90% air, 8% water and 1% abrasive is produced as a cutting beam and in the water-abrasive suspension jet has a composition of about 97% water and 3% abrasive is produced as a cutting jet. As Äbrasivmittel are garnet or corundum, but also so-called Barton Gamet Fe₃Al₂(SiO₄)_S, Silicon carbide or aluminum oxide used. The size of the grains of the abrasive materials used here is usually to between 70 to 200 micrometers.

p0005Hereinafter, the following terminology will be used:

p0006An abrasive material acting (usually a mineral solids) is referred to as abrasive. The medium used for cutting, for example a liquid or a suspension, which contains abrasive material is referred to as Äbrasivmittel.

p0007A problem with the waterjet is the disposal of the forming sludge which forms of spent abrasive and separated constituents of the material to be cut material. The water jet provided with abrasive material is collected along with produced during machining the workpiece to be machined material particles after cutting. This mixture must either be disposed of or processed. For preparation, it is known, non-ferromagnetic

p0008Abrasive / abrasive separate again in the separation process according to the flotation principle. In ferromagnetic materials, it is known, this with the help of magnetic fields separate, and thus each reclaim portions of the abrasive / of abrasive material.

p0009Depending on the composition of the resulting mixture / slurry it can be problematic, this reprocess, because the preparation of the mixture / slurry comprises additional steps and related additional production costs.

p0010In particular, the preparation of the Wasserabra- sivstrahlschneiden resulting plastic particles or certain metal particles (containing z. B. chromium or other heavy metals particles) or mixtures thereof can be problematic.

p0011In DE 198 43 683 Al has been proposed, for example, obtained as abrasive industrial sludge, in particular rolling and / or forging mud or WaIz- and / or forging scale use. but this must be brought to an environmentally acceptable residual oil content for use, before it can be used as the abrasive, since its use for environmental reasons is otherwise problematic. The oil removal is complicated and therefore expensive. In addition, the abrasive action of the rolling and / or forging sludge or rolling and / or

p0012Wrought scale often not sufficient if the are particularly hard or particularly thick materials to be cut.

p0013The invention is based on the object of a

p0014state solution, which provides an effective and cost-effective abrasive, which is available in large quantities in a consistent quality and which can be discarded after its use in abrasivejet preferably without great technical effort. The above object is inventively achieved by a

p0015A process for preparing an abrasive for the

p0016Abrasivejet solved according to claim. 1 Likewise, the above object is inventively achieved by a

p0017Abrasive dissolved claim 15th Further, the above object is achieved according to the use to

p0018Claim 24 is released. Finally, the object is also achieved by a Abrasivstrahlschneidverfahren claim 27th

p0019Expedient refinements and advantageous developments of the invention result from the respective dependent claims.

p0020In particular, in a method of the type described, the object is achieved in that the Abrasivmmittel containing an abrasive material, containing at least 5 wt .-% TiO₂, Preferably 25 to 85 wt .-% TiO 2, contains. Preferably, the invention

p0021Abrasivmmittel as abrasive an intermediate or by-product from the production of titanium dioxide.

p0022It is particularly advantageous when the TiC> 2 is present in the rutile modification in the abrasive.

p0023It has been found, surprisingly, that in the

p0024Preparation of titanium dioxide used raw material

p0025(Example Ilrαenit, rutile or titanium slag) and / or of the TiO₂-Sulfatverfahren Resulting digestion residue and / or the SiO₂~ Can containing residue which is generated in the production of titanium dioxide by the chloride process at step chlorination find, as abrasive when abrasivejet, particularly waterjet, use. The digestion residue which is generated in the production of titanium dioxide by the sulphate process, is produced in the manner that a titanium-containing starting raw material, especially ilmenite and / or titanium-containing slag is digested with sulfuric acid and from the resulting digestion solution by solids separation, particularly filtration, the digestion residue product the form of a solid is obtained containing mass. The digestion residue usually contains about 30 to 70% TiO₂,

p0026The SiO2-containing residue which is obtained in the production of titanium dioxide by the chloride process at step chlorination, produced in the manner that a titanium-containing starting raw material, in particular of natural or synthetic rutile or titanium-containing slag is reacted with coke and chlorine and Besides gaseous reaction products and solid SiO₂-containing residues apply and be deducted either continuously or intermittently from the chlorination reactor.

p0027The requirements for the abrasive abrasivejet, namely cost and available in large quantities at a constant quality abrasive materials, is met by the products of the invention in its entirety. Because the Ti0₂Component caused due to the Mohs hardness - especially when the TiO₂ is present in the rutile - the abrasive action, while the origin at reasonable cost, the availability of a constant quality of industrial processes safely.

p0028At the same abrasive material according to the invention, due to the TiO₂~ Content after waterjet collected mixed with the waste particles produced during the cutting and processing of the respective workpiece and for disposal a melting furnace, particularly a blast furnace, are fed. The high temperatures of a melting furnace along with the exhaust gas purification devices located on a furnace, today will ensure environmentally friendly disposal of the particles. Here, the iron- and titanium-containing particles of this mixture are also raw or aggregates, which are used in the production of pig iron or metal production in furnaces use. So it is no longer necessary to dispose of the resulting waste mixture at abrasivejet (mud). It can be cost-effective, supplied as an additive in a melting process a furnace, particularly a blast furnace. Optionally previously be made in the form of a classification and / or drying can be reprocessed. Alternatively, the abrasive material used can be reintroduced into the process stream of titanium dioxide production.

p0029Especially advantageous is the greater compared to conventional abrasive materials fineness of the abrasive particles according to the invention. Thereby, it is possible that the diameter of the Fokussierrohres (hereinafter referred to as nozzle diameter) through which the outlet of the abrasive jet is less than 0.5 mm, preferably less than 0.35 mm, particularly preferably less than 0.2 mm, are selected can. In this way, smaller cutting widths, less material consumption (of abrasive and material) and a lesser amount of residue can be achieved. This is particularly advantageous for thin materials.

p0030In particular, the digestion residue material produced during the production of titanium dioxide by the sulphate process is then suitable material for use as abrasive in abrasivejet when the digestion residue product neutralized with sodium hydroxide and a Abrasivstrahlschneidvorrichtung is supplied. By neutralizing with sodium hydroxide solution are water soluble salts which, when the digestion residue is dried, contribute to an increased strength of the resulting particles form granules in the drying process. In particular, sodium sulfate, which is otherwise washed out of the digestion residue at usual Titandioxidherstellverfahren, does not need to be washed, but can be used directly as a useful component of the abrasive material. This results in savings in Titandioxidherstellverfahren that affect the price and thus the competitiveness of the abrasive material from digestion residue positive result.

p0031Since the use of powdered or granular abrasive material both lower transport costs caused as can also be used with the same devices as the sand-like materials commonly used, therefore, the invention provides, in an embodiment also provides that the digestion residue product for front feed

p0032Abrasivstrahlschneidvorrichtung is dried. Preferably drying is carried out by spray drying or Spimflashtrocknung as regularly shaped in this way, can be obtained in about the same size and stable granules.

p0033but it is also possible that the Aufschlussrückstandspro- uct in the form of a suspension was prepared and the Abrasivstrahlschneidvorrichtung is supplied in this form as abrasive. In this way, the introduction and metering of the abrasive by simply

p0034Pumps be accomplished particularly easily into the water jet, with which the process steps of solids conveying, the solid dosage and mixing of abrasive and water can be omitted. In the event that the digestion residue product is subjected to a drying process, it may be in accordance with an expedient development of the invention advantageous if the digestion residue product is subjected during or after drying a granulation process. This makes it possible, the particle size of the individual Abrasivpartikels, ie the agglomerate of digestion residue product particles to specifically set in a certain range and to agglomerate the fine particulate starting material.

p0035The invention is therefore characterized in further by the fact that a granular abrasive material is produced, having a granular particle size of 10 to 600 .mu.m, more preferably 30 to 400 .mu.m, preferably 50 to 300 microns.

p0036An advantage of the abrasive materials according to the invention is that the solid particles are much finer than the materials commonly used to obtain a finer water jet can be used.

p0037The titanium-containing abrasive material can also be brought by screening, classification by means of a hydrocyclone or other classification assemblies to a mean particle size of less than 50 microns, preferably less than 15 microns, more preferably to less than 10 microns.

p0038Appropriately, an abrasive material is thereby produced according to embodiment of the invention, the

p0039Solid particles having an average primary particle size of 3 to 50 .mu.m, preferably 10 to 30 microns containing, or consisting of, wherein the solid particles preferably digestion residue product particles, ie the particles of the digestion residue product is. In order to influence the hardness of the granulated particles of abrasive material is positive, the invention further provides that 0.5 to 10 wt .-% are included, in particular 3.0 to 7.0 wt .-% of inorganic salts. Also advantageous is the addition of 0.5 to 30 wt .-%, in particular 3 to 10 wt .-% of water glass (calculated as SiO₂ and based on the water-insoluble solids) to improve the stability of granules.

p0040To the abrasive material to process after abrasivejet in the form of the forming slurry form residue in a furnace well and without any problems, in particular egg produced n abrasive, which contains at least. 5% TiO₂, Preferably 25 to 85 wt .-% TiO₂contains.

p0041A particularly favorable drying of normally present in the production of titanium dioxide by the sulphate process in the form of a suspension digestion residue can be achieved, in particular by spray-drying, so that the invention is characterized further in that the abrasive material is produced by spray drying.

p0042but it is also possible, the abrasive usual to optimize its Abrasivverhaltens abrasive materials for the

p0043admix waterjet, it can be provided that the abrasive SiO₂-containing sand, garnet sand in particular, is admixed. Preferably, the abrasive material in the abrasive waterjet contains at least 10%, preferably at least 70%, of the titanium-containing

p0044Abrasive material.

p0045The advantage of such a mixture may consist in reaching a higher solids content in the abrasive jet, or in a greater range of variation in the optimization of the overall system.

p0046The above object is also achieved by a titanium-containing abrasive material consisting of, or which is obtained containing intermediates or by-products from the production of titanium dioxide, especially digestion residue in the production of titanium dioxide by the sulphate process, the abrasive material from 0.5 to 20 wt.%, In particular 3 to 8% wt. based on alkaline sulfate to the water-insoluble solids content and is present in dried form. Preferably, the titanium-containing abrasive material is in the form of granules having a mean granule particle size of 10 to 600 .mu.m, preferably 30 to 400 .mu.m, particularly 50 to 300 microns, before.

p0047The above object is also achieved by an abrasive, which is in the form of a suspension, which can be stabilized by an organic additive. this is particularly suitable is a polyacrylate, which preferably 0.5% to 4%, based on the water-insoluble solid is added in an amount of 0.01% to 10%.

p0048Further advantages of the abrasive agent result from the respective dependent claims.

p0049Further, the above object is also solved by the use of a titanium-containing Abrasivraaterials in the form of intermediates or by-products from the titanium dioxide production, in particular in the production of titanium dioxide by the

p0050Sulphate process resulting digestion residue or the scraps left over from chloride process SiO₂-containing residue sivstrahlschneiden when abrasivejet, especially Wasserabra-. With this use are the same associated advantages which are listed above for the method and the abrasive.

p0051Embodiments of use arising from the related subclaims.

p0052In one embodiment of the invention, the resulting in the production of titanium dioxide by the sulphate process digestion residue (Industrial Inorganic Pigments, G. Buxbaum, G. Pfaff (ed.), 3rd edition,

p0053Wiley-VCH, Weinheim 2005) in the form of a filter cake is then neutralized with sodium hydroxide for example, and then a drying process, in particular a spray drying supplied. Subsequently, the spray-dried digestion residue product to a desired particle size, in particular between 30 and 400 .mu.m, granulated and then stored in a silo or bunker. For this silo or bunker the Abra is sivmaterial packed into packaging containers and place for hardening, ie the location of an Abrasivstrahlschneidvorrichtung transported. There it is supplied as a conventional abrasive Wasserabrasivstrahlvorrichtung by which then a material to be treated is cut. The resulting water / abrasive / product material mixture is collected and the solid fraction is separated from the liquid fraction. The separated solids is then, possibly after intermediate storage or drying, to a melting furnace, particularly a blast furnace, transported and used there as aggregate material.

p0054In the conventional abrasivejet with garnet sand abrasive jet contains only about 10 percent .-% abrasive. It is therefore particularly advantageous to use a highly concentrated Abrasivmaterialsuspension which has a solids content of> 40%, preferably> 50%, particularly preferably > 55% having. In this way, a particularly effective cutting action can be achieved.

p0055The high content of abrasive material in the Abrasivmaterialsuspension is achieved that {based on the water-insoluble solids) from 0.1 to 10 wt .-%, preferably 0.5 to 4.0 wt .-%, of an organic dispersing aid, preferably a polyacrylate, is added.

p0056Such stable suspensions are preferably obtained with a particularly finely divided abrasive material, such as. With a primary particle size with a dgo value of less than 50 microns, preferably less than 15 microns, more preferably less than 10 microns

p0057example:

p0058Digestion residue from titanium dioxide production by the sulphate process was initially separated from the black liquor by filtration, then resuspended the resulting filter cake and neutralized with sodium hydroxide (pH = 6 to 9). The neutralized slurry thus obtained was dried in a spray dryer with atomizer. In this case, granular particles were obtained with an average diameter of 20 to 50 microns. The Sprühgranulatpartikel obtained were used in the same manner as garnet for waterjet cutting a 25 mm thick steel plate. The speed of the cutting process was thereby only slightly lower than when using garnet sand.

p0059example:

p0060Digestion residue from titanium dioxide production by the sulphate process was initially separated from the black liquor by filtration, then resuspended the resulting filter cake and neutralized with sodium hydroxide (pH = 6 to 9) and filtered again by a filter press. The neutralized filter cake was added to a polyacrylate with 2 wt .-% (based on the solids content) and transferred into a suspension with a solids content of 65%.

p0061The suspension thus obtained showed even after several weeks of storage no signs of sedimentation and was converted by gentle stirring at any time in a homogeneous suspension.

p0062The titanium-containing abrasive material may be an intermediate or by-product from the production of titanium dioxide, containing ground ilmenite or milled titanium slag.

p0063The titanium-containing abrasive material may be digestion residue which is obtained as an insoluble residue in the production of titanium dioxide by the sulphate process and is separated from the so-called black liquor.

p0064The titanium-containing abrasive material may contain the SiO2-containing residue which is obtained in the production of titanium dioxide by the chloride process at step chlorination.

p0065The TiO₂ the abrasive material can in particular in the

p0066Rutile present.

p0067The abrasive in waterjet may be made at least 10 wt .-%, preferably at least 70 wt .-%, of the titanium-containing abrasive.

p0068The abrasive can be supplied in the form of a suspension of the Abrasivstrahlschneidevorrichtung, wherein the step of mixing the abrasive material with water is no longer needed in the Abrasivstrahlschneidevorrichtung.

p0069The titanium-containing abrasive material, by sieving, classification by means of a hydrocyclone or other classification assemblies to a mean particle size of less than 50 Mikroometer, preferably to less than 15 microns, more preferably to less than 10 microns, placed.

p0070The water produced in the neutralization or partial neutralization sulfate salt is not removed and / or the digestion residue is 0.5 to 30 wt.%, Particularly 3 to 10 wt.% Of water glass (calculated as SiOj and related to the water-insoluble solids) was added.

p0071The titanium-containing abrasive material is converted into an aqueous suspension and this suspension is by means of an organic additive, preferably a polyacrylate, stabilized with 0.01 wt .-% to 10 wt .-%, preferably 0.5 wt .-% to 4 may be added wt .-%, of organic additives with respect to the water-insoluble solids.

p0072The abrasive can after the waterjet collected and optionally together with other

p0073Residues of a Wasserabrasivstrahlschneidens

p0074Collecting in a melting furnace, particularly a blast furnace, are fed, optionally above a

p0075Treatment is carried out in the form of a classification and / or drying.

p0076The titanium-containing abrasive material consisting of or containing intermediates or by-products from the titanium dioxide production, in particular digestion residue, which in the production of titanium dioxide by the Sulphate process is obtained, can be 0.5 to 20 wt.%, In particular 3 to 8 wt.%, Relative to alkali metal sulphate contained in the water-insoluble solids content and be present in dried form.

p0077A Abrasivmaterialsuspension can have a solids content of> 40%, preferably> 50%, particularly preferably> 55%, and 0.1 to 10 wt .-%, preferably 0.5 to 4.0 wt .-% of an organic dispersion aid, based the water-insoluble solid comprise.

p0078It has also been surprisingly found that the solid obtained from the resulting titanium-containing suspension in the production of titanium dioxide, in particular by the sulfate process after the digestion of the titaniferous raw material by separation can be found as abrasive when abrasivejet cutting, particularly waterjet, use. The present in the resulting solids-containing mass solid particles have a hardness that is sufficient to be used as abrasive material. The so obtained abrasive material, which mostly from undigested titaniferous raw materials, and thus essentially of TiO₂ oxide and iron oxide, can be produced by the waterjet in a mixture with the in

p0079caught cutting and processing of the respective workpiece resulting waste particles and disposed of in a furnace, particularly a blast furnace, are fed. located The high temperatures of a furnace together with the melting furnace at a today

p0080Emission control devices will ensure environmentally friendly disposal of the particles. Here, the iron- and titanium-containing particles of this mixture are also raw or aggregates, which are used in the production of pig iron or metal production in furnaces use. It is therefore no longer necessary, the resulting mixture at abrasivejet waste (sludge) recycle. It can be cost-effective, supplied as an additive in a melting process a furnace, particularly a blast furnace. It is also not necessary to recover the abrasive or abrasive cost reasons, as this in the titanium dioxide production than to be disposed of by-product (digestion residue) produced and directly, ie use as abrasives or abrasive material can be fed without further purification step. The abrasive or abrasive material is thus available at low cost. Also likely to be cost-effective, as the resultant of abrasive when conducting purification process for recovering costs. In particular, these same purification procedures are technically saved and no longer needed.

p0081The abrasive may be a abrasive material, which is obtained during the digestion of titanhaltigern raw material with sulfuric acid and 0.5 to 10 wt.%, In particular 3 to 7 wt.%, Of inorganic salts, preferably good water-soluble salts, particularly preferably alkali metal sulfate.

p0082The digestion residue product and thus the abrasive may further comprise solid particles having an average primary particle size of 1 to 50 microns, especially 3 to 30 microns. Such abrasive is also inexpensive to produce and is suitable to be used as abrasives in abrasivejet, particularly waterjet, and it can also easily environmentally friendly manner in a furnace, particularly a blast furnace together or disposed of in a mixture with further nascent during waterjet residue material. In one embodiment of the invention, resulting in the production of titanium dioxide by the sulphate process digestion residue is neutralized in the form of a filter cake, for example with sodium hydroxide solution and then a drying process, in particular a spray-drying is supplied. Subsequently, the spray-dried digestion residue product to a desired particle size, in particular between 30 and 400 .mu.m, granulated and then stored in a silo or bunker. For this silo or bunker the Abra is sivmaterial packed into packaging containers and to the site, ie the location of an Abrasivstrahlschneidvorrichtung transported. There it is supplied as a conventional abrasive Wasserabrasivstrahlvorrichtung by which then a material to be treated is cut. The resulting water / abrasive / product material mixture is collected and the solid fraction is separated from the liquid fraction. The separated solids is then, possibly after intermediate storage or drying, to a melting furnace, particularly a blast furnace, transported and used there as aggregate material.

p0083In a further embodiment of the invention, the used titanium-containing raw material, ilmenite or titanium slag is first dried to a moisture content% <0, l, and ground to the desired average grain size. the milled titanium raw materials are then mixed with sulfuric acid and the reaction is started in the digestion tank by adding water in a batch digestion process. After carrying out the digestion reaction and the

p0084Maturing phase, the digestion mass dissolved and a solution having a Ti0₂Concentration of 8 to 12 wt.% (Ilmenite digestion) or 13 to 18 wt.% (Slag digestion) formed. From the resulting solution all undigested solids are then using thickener, Rotary vacuum filter or filter press as completely separated from the solution. The case containing in the form of a solid mass resulting digestion residue in the form of a filter cake is then neutralized with sodium hydroxide and then a drying process, in particular a spray drying supplied. Subsequently, the spray-dried digestion residue product to a desired particle size, particular from 30 to 400 microns, granulated and then stored in a silo or bunker. For this silo or bunker the Abra is sivmaterial packed into packaging containers and to the site, ie the location of an Abrasivstrahlschneidvorrichtung transported. There it is fed as a common Abrasivπiittel Wasserabrasivstrahlvorrichtung by which then a material to be treated is cut. The resulting water / abrasive / product material mixture is collected and the solid fraction is separated from the liquid fraction. The separated solids is then, optionally after intermediate storage, to a melting furnace, particularly a blast furnace, transported and used there as aggregate material.