EP1833764A1 - Verfahren zur reduktion des löslichen chromatgehaltes in zement sowie eine zubereitung aus zement und wasserlöslichen metallsulfaten - Google Patents
Verfahren zur reduktion des löslichen chromatgehaltes in zement sowie eine zubereitung aus zement und wasserlöslichen metallsulfatenInfo
- Publication number
- EP1833764A1 EP1833764A1 EP05813617A EP05813617A EP1833764A1 EP 1833764 A1 EP1833764 A1 EP 1833764A1 EP 05813617 A EP05813617 A EP 05813617A EP 05813617 A EP05813617 A EP 05813617A EP 1833764 A1 EP1833764 A1 EP 1833764A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- iron
- weight
- reducing agent
- sulfate
- sulphate
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
- 239000004568 cement Substances 0.000 title claims abstract description 53
- ZCDOYSPFYFSLEW-UHFFFAOYSA-N chromate(2-) Chemical compound [O-][Cr]([O-])(=O)=O ZCDOYSPFYFSLEW-UHFFFAOYSA-N 0.000 title claims abstract description 14
- 238000000034 method Methods 0.000 title claims description 33
- 238000002360 preparation method Methods 0.000 title claims description 20
- 230000009467 reduction Effects 0.000 title claims description 8
- 229910052751 metal Inorganic materials 0.000 title description 23
- 239000002184 metal Substances 0.000 title description 23
- 150000003467 sulfuric acid derivatives Chemical class 0.000 title description 17
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims abstract description 99
- BAUYGSIQEAFULO-UHFFFAOYSA-L iron(2+) sulfate (anhydrous) Chemical compound [Fe+2].[O-]S([O-])(=O)=O BAUYGSIQEAFULO-UHFFFAOYSA-L 0.000 claims abstract description 98
- 239000003638 chemical reducing agent Substances 0.000 claims abstract description 67
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims abstract description 58
- 229910000359 iron(II) sulfate Inorganic materials 0.000 claims abstract description 37
- 229910052742 iron Inorganic materials 0.000 claims abstract description 28
- 150000003839 salts Chemical class 0.000 claims abstract description 26
- 239000010802 sludge Substances 0.000 claims abstract description 17
- 239000000725 suspension Substances 0.000 claims abstract description 15
- 150000002506 iron compounds Chemical class 0.000 claims abstract description 14
- 238000004519 manufacturing process Methods 0.000 claims abstract description 14
- 230000008569 process Effects 0.000 claims description 21
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 claims description 20
- 239000002253 acid Substances 0.000 claims description 13
- 238000002425 crystallisation Methods 0.000 claims description 13
- 230000008025 crystallization Effects 0.000 claims description 13
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 claims description 11
- 239000004408 titanium dioxide Substances 0.000 claims description 10
- 238000006243 chemical reaction Methods 0.000 claims description 8
- 229910021653 sulphate ion Inorganic materials 0.000 claims description 8
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 8
- 238000000926 separation method Methods 0.000 claims description 7
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 claims description 6
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims description 6
- 229910000358 iron sulfate Inorganic materials 0.000 claims description 6
- 239000010936 titanium Substances 0.000 claims description 6
- 229910052719 titanium Inorganic materials 0.000 claims description 6
- 230000003647 oxidation Effects 0.000 claims description 5
- 238000007254 oxidation reaction Methods 0.000 claims description 5
- NCNCGGDMXMBVIA-UHFFFAOYSA-L iron(ii) hydroxide Chemical compound [OH-].[OH-].[Fe+2] NCNCGGDMXMBVIA-UHFFFAOYSA-L 0.000 claims description 4
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 claims description 3
- 235000014413 iron hydroxide Nutrition 0.000 claims description 3
- 229910052748 manganese Inorganic materials 0.000 claims description 3
- 239000011572 manganese Substances 0.000 claims description 3
- RAQDACVRFCEPDA-UHFFFAOYSA-L ferrous carbonate Chemical compound [Fe+2].[O-]C([O-])=O RAQDACVRFCEPDA-UHFFFAOYSA-L 0.000 claims description 2
- 238000011049 filling Methods 0.000 claims description 2
- 238000000227 grinding Methods 0.000 claims description 2
- 238000004806 packaging method and process Methods 0.000 claims description 2
- 235000013980 iron oxide Nutrition 0.000 claims 2
- 238000002156 mixing Methods 0.000 claims 1
- 230000001603 reducing effect Effects 0.000 abstract description 6
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 8
- 229910052804 chromium Inorganic materials 0.000 description 8
- 239000011651 chromium Substances 0.000 description 8
- SURQXAFEQWPFPV-UHFFFAOYSA-L iron(2+) sulfate heptahydrate Chemical compound O.O.O.O.O.O.O.[Fe+2].[O-]S([O-])(=O)=O SURQXAFEQWPFPV-UHFFFAOYSA-L 0.000 description 8
- 238000003860 storage Methods 0.000 description 7
- 238000001704 evaporation Methods 0.000 description 6
- 230000008020 evaporation Effects 0.000 description 6
- 238000001914 filtration Methods 0.000 description 6
- 239000000203 mixture Substances 0.000 description 6
- 230000000694 effects Effects 0.000 description 4
- 239000005569 Iron sulphate Substances 0.000 description 3
- JOPOVCBBYLSVDA-UHFFFAOYSA-N chromium(6+) Chemical compound [Cr+6] JOPOVCBBYLSVDA-UHFFFAOYSA-N 0.000 description 3
- 238000001816 cooling Methods 0.000 description 3
- 239000007791 liquid phase Substances 0.000 description 3
- 206010020751 Hypersensitivity Diseases 0.000 description 2
- 208000026935 allergic disease Diseases 0.000 description 2
- 230000007815 allergy Effects 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 150000004682 monohydrates Chemical class 0.000 description 2
- IYVLHQRADFNKAU-UHFFFAOYSA-N oxygen(2-);titanium(4+);hydrate Chemical compound O.[O-2].[O-2].[Ti+4] IYVLHQRADFNKAU-UHFFFAOYSA-N 0.000 description 2
- 239000000047 product Substances 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 238000011084 recovery Methods 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 239000002699 waste material Substances 0.000 description 2
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 description 1
- VTLYFUHAOXGGBS-UHFFFAOYSA-N Fe3+ Chemical compound [Fe+3] VTLYFUHAOXGGBS-UHFFFAOYSA-N 0.000 description 1
- 206010067482 No adverse event Diseases 0.000 description 1
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 238000001354 calcination Methods 0.000 description 1
- BFGKITSFLPAWGI-UHFFFAOYSA-N chromium(3+) Chemical compound [Cr+3] BFGKITSFLPAWGI-UHFFFAOYSA-N 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 239000012141 concentrate Substances 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 230000029087 digestion Effects 0.000 description 1
- 229960004887 ferric hydroxide Drugs 0.000 description 1
- 239000012065 filter cake Substances 0.000 description 1
- 239000010440 gypsum Substances 0.000 description 1
- 229910052602 gypsum Inorganic materials 0.000 description 1
- 150000004688 heptahydrates Chemical class 0.000 description 1
- UCNNJGDEJXIUCC-UHFFFAOYSA-L hydroxy(oxo)iron;iron Chemical compound [Fe].O[Fe]=O.O[Fe]=O UCNNJGDEJXIUCC-UHFFFAOYSA-L 0.000 description 1
- ZTEAHBPTRRHAEW-UHFFFAOYSA-L iron(2+);dihydroxide;hydrate Chemical compound O.[OH-].[OH-].[Fe+2] ZTEAHBPTRRHAEW-UHFFFAOYSA-L 0.000 description 1
- RUTXIHLAWFEWGM-UHFFFAOYSA-H iron(3+) sulfate Chemical compound [Fe+3].[Fe+3].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O RUTXIHLAWFEWGM-UHFFFAOYSA-H 0.000 description 1
- IEECXTSVVFWGSE-UHFFFAOYSA-M iron(3+);oxygen(2-);hydroxide Chemical compound [OH-].[O-2].[Fe+3] IEECXTSVVFWGSE-UHFFFAOYSA-M 0.000 description 1
- 229910021506 iron(II) hydroxide Inorganic materials 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- SQQMAOCOWKFBNP-UHFFFAOYSA-L manganese(II) sulfate Chemical compound [Mn+2].[O-]S([O-])(=O)=O SQQMAOCOWKFBNP-UHFFFAOYSA-L 0.000 description 1
- 229910000357 manganese(II) sulfate Inorganic materials 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- 230000035800 maturation Effects 0.000 description 1
- 150000002736 metal compounds Chemical class 0.000 description 1
- 238000006386 neutralization reaction Methods 0.000 description 1
- NDLPOXTZKUMGOV-UHFFFAOYSA-N oxo(oxoferriooxy)iron hydrate Chemical compound O.O=[Fe]O[Fe]=O NDLPOXTZKUMGOV-UHFFFAOYSA-N 0.000 description 1
- 239000012071 phase Substances 0.000 description 1
- 235000021110 pickles Nutrition 0.000 description 1
- 238000005554 pickling Methods 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 238000004064 recycling Methods 0.000 description 1
- 239000008247 solid mixture Substances 0.000 description 1
- 229910052717 sulfur Inorganic materials 0.000 description 1
- 239000011593 sulfur Substances 0.000 description 1
- 238000010626 work up procedure Methods 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
- C04B28/02—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing hydraulic cements other than calcium sulfates
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
- C01G49/00—Compounds of iron
- C01G49/14—Sulfates
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B22/00—Use of inorganic materials as active ingredients for mortars, concrete or artificial stone, e.g. accelerators, shrinkage compensating agents
- C04B22/08—Acids or salts thereof
- C04B22/14—Acids or salts thereof containing sulfur in the anion, e.g. sulfides
- C04B22/142—Sulfates
- C04B22/149—Iron-sulfates
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B40/00—Processes, in general, for influencing or modifying the properties of mortars, concrete or artificial stone compositions, e.g. their setting or hardening ability
- C04B40/0028—Aspects relating to the mixing step of the mortar preparation
- C04B40/0039—Premixtures of ingredients
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
- C04B2111/10—Compositions or ingredients thereof characterised by the absence or the very low content of a specific material
- C04B2111/1075—Chromium-free or very low chromium-content materials
- C04B2111/1081—Chromium VI, e.g. for avoiding chromium eczema
Definitions
- the invention relates to a process for the preparation of a reducing agent for reducing the soluble chromate content in cement and a preparation of cement and water-soluble metal sulfates.
- the chromium content of cements is usually between 10 ppm and 100 ppm, depending on the raw material used.
- the chromium contained in the cement can go into solution when mixed with water as chromium (VI) and sensitize the skin with frequent contact and trigger a chromium allergy, the so-called Maurerkrätze.
- VI chromium
- Maurerkrätze To protect against the chromium allergy, it is possible to chemically reduce the chromium (VI) to chromium (III) and thus to drastically reduce the solubility.
- the reducing agent used in the cement industry mainly iron (II) sulfate (as heptahydrate or monohydrate) to achieve a chromium (VI) content of less than 2 ppm (see Locher, Friedrich Wilhelm: cement: basics of production and Use, Verlag Bau +technik GmbH, Dusseldorf 2000).
- EP 0 054 314 A1 EP 0 160 746 A1 and EP 0 160 747 A1 describe the addition of iron sulphate to the ground cement, the iron sulphate being added to the cement in dry form before the cement storage silo. According to EP 0 160 747 A1, the iron sulfate is coated to increase the oxidation resistance.
- the iron (II) sulfate originates entirely from the titanium dioxide production by the sulphate process, in which process it is obtained as a by-product.
- the iron (II) sulfate can be obtained in this process by crystallization from the sulfuric acid, titanium and iron-containing solution obtained in the digestion of titanium and iron ores or synthetic raw materials, the so-called black solution. During the crystallization of the black solution, some but not all of the iron is removed from the solution.
- the crystallization of the iron (II) sulfate is carried out by vacuum cooling and optionally additional evaporation. After separation of the iron (H) sulfate (iron (II) sulfate heptahydrate), the remaining solution is hydrolyzed.
- the titanium oxide hydrate thus obtained is separated by filtration from the remaining so-called dilute acid. As the titanium oxide hydrate is further processed to titanium dioxide, the dilute acid must be made available for further recovery or suitably converted to harmless compounds.
- iron (II) sulfate heptahydrate can be obtained by crystallization in a similar manner as described above for the recovery of iron (II) sulfate heptahydrate from the so-called black solution.
- EP 0 132 820 A1 describes the possibility of separating off the dilute acid before concentrating iron (II) sulfate heptahydrate.
- a disadvantage is stated that in such a separation of iron (II) sulfate heptahydrate remaining metal sulfates remain in the waste acid and that for the separated iron (II) sulfate heptahydrate (green salt) do not exist sufficient uses.
- a process for the preparation of an iron (II) sulphate-containing reducing agent which comprises a crystallization of iron (II) sulphate-containing salts from an iron (II) sulphate-containing sulfuric acid is known from DE 103 32 530 A1.
- the reducing agent obtained by this process is used to reduce the soluble chromate content in cement.
- the indication that the precipitated during crystallization iron (II) sulfate-containing reducing agent separated from the sulfuric acid and then used the filter cake thus obtained as iron (II) sulfate-containing reducing agent for chromate reduction for cement becomes. Accordingly, a filtration step is necessary for the preparation of the reducing agent, in which case other metal sulfates than the iron sulfate or iron sulfate heptahydrate may optionally remain in the sulfuric acid or dilute acid.
- the object of the invention is to provide an iron (II) sulphate-containing reducing agent for the soluble chromate in cement and suitable production processes therefor.
- This object is achieved according to the invention by a process for preparing an iron (II) sulphate-containing reducing agent comprising crystallization of iron (II) sulphate-containing salts from an iron (II) sulphate-containing sulfuric acid and direct reaction of the resulting iron (II) sulphate-containing salts and sulfuric acid comprehensive suspension (thick sludge) with iron and / or one or more iron compounds to the iron (II) sulphate-containing reducing agent, without any separation of the sulfuric acid from the iron (II) sulfate-containing salts.
- the process according to the invention thus initially comprises the crystallization of iron (II) sulphate-containing salts from an iron (II) sulphate-containing sulfuric acid. After crystallization, a mixture is present which comprises the precipitated iron (II) sulphate-containing salts, precipitated metal salts and residual sulfuric acid.
- the reaction of the iron (s) added to the suspension (thick sludge) or the iron compound (s) added to the suspension (thick sludge) with the sulfuric acid present in the resulting suspension (thick sludge) allows the pH of the suspension (thick sludge) to be increased to a higher value be set.
- ground limestone (CaCO 3 ) or other Mg or Ca-containing material may additionally be added in order to purposefully optimize the pH of the mixture or the rheological properties.
- the crystallization of the iron (II) sulphate-containing and other metal salts (metal sulphates) can take place in evaporation plants with attached salt maturation (cooling).
- the existing metal sulfates can crystallize out as sulfates, hydrogen sulfates, oxysulfates or as a complex mixture thereof.
- the iron (II) sulphate-containing metal salts (metal sulphates) obtained by the process according to the invention can be used as iron (II) sulphate-containing reducing agent for chromate reduction for cement.
- Particularly advantageous in this method is that all of the preferably 50-70% sulfuric acid auskristall accrue metal sulfates are recycled.
- iron (II) sulfate Including iron sulfate and other metal sulfates with also reducing character, z. B. manganese (II) sulfate.
- Others in the iron (II) sulphate-containing reducing agent obtained in small amounts according to the invention further metal sulfates show no adverse effects in the cement and are permanently integrated in the cement matrix after curing.
- the iron (II) sulfate-containing reducing agent obtained according to the invention despite the additional introduction of chromium into the cement, the content of undesired soluble chromium can be effectively and sufficiently reduced.
- the iron compounds used for the reaction may be selected from the group consisting of iron oxide, iron hydroxide, iron oxide hydrate, iron hydroxide hydrate and / or iron carbonate.
- the iron of the iron compound preferably has the oxidation state II.
- at least a portion of the iron in the iron compound may also be present in the oxidation state III, in which case metallic iron is added at the same time, which is a partial or complete reduction of the Fe (III) causes.
- the invention provides that an iron (II) sulphate-containing reducing agent having a titanium content based on the iron of> 1% by weight to ⁇ 20% by weight, preferably> 2% by weight to ⁇ 8% by weight, particularly preferred > 3% by weight to ⁇ 6% by weight and / or with a manganese content based on the iron of> 0.1% by weight to ⁇ 10% by weight, preferably> 1% by weight to ⁇ 7% by weight, especially preferably> 1.5% by weight to ⁇ 4% by weight manganese is produced.
- an iron (II) sulphate-containing reducing agent having a titanium content based on the iron of> 1% by weight to ⁇ 20% by weight, preferably> 2% by weight to ⁇ 8% by weight, particularly preferred > 3% by weight to ⁇ 6% by weight and / or with a manganese content based on the iron of> 0.1% by weight to ⁇ 10% by weight, preferably> 1% by weight to ⁇ 7% by weight, especially preferably> 1.5% by weight
- the metal sulfates preferably in the processing of iron (II) sulfate-containing used sulfuric acid after concentration of the sulfuric acid to> 50% to ⁇ 90%, preferably> 60% to ⁇ 80%, particularly preferably> 65% to ⁇ 75% precipitate.
- the invention therefore further provides for the sulfuric acid to crystallize the iron (II) sulfate-containing salts to a concentration of> 50% to ⁇ 90%, preferably> 60% to ⁇ 80%, more preferably> 65% to ⁇ 75% becomes.
- the acid is preferably concentrated to> 45% to ⁇ 55% (total sulfuric acid content, which corresponds to about 70% sulfuric acid concentration in the liquid phase) crystallized by crystallization of the main iron (II) sulfate-containing metal salts formed suspension (thick sludge) by cooling on.
- the concentration can be continuous or discontinuous in evaporation plants by evaporation or evaporation of the water under atmospheric pressure or vacuum; preferably continuously operated forced circulation evaporator plants are used under vacuum.
- iron (II) sulphate-containing used sulfuric acids from which the iron (II) sulphate-containing reducing agent is obtained after concentration and after the crystallization phase.
- iron (II) sulphate-containing used sulfuric acids from the metal pickle are suitable for this, which is why the invention is also distinguished by the fact that the iron (II) sulphate-containing reducing agent consists of an (II) sulphate-containing second-hand sulfuric acid made from a metal pickling process.
- iron (II) sulphate spent sulfuric acids It is also possible to use mixtures of iron (II) sulphate spent sulfuric acids. Finally, it is also possible to use iron (III) sulphate-containing second-hand sulfuric acids, provided that they have been previously reduced with metallic iron or other reducing agents.
- the effectiveness of the iron (II) sulphate reducing agent obtained by the process according to the invention, when added to cement or to the cement-water mixture in the processing of cement, is comparable to that of conventionally used iron (II) sulphate heptahydrate or green salt.
- the invention therefore also provides that the iron (II) sulfate-containing reducing agent prepared by the process according to the invention is used in cement for chromate reduction. It is then according to another embodiment of the invention is advantageous if the cement> 0.01% by weight to ⁇ 5% by weight, preferably> 0, l weight% to ⁇ 3% by weight, particularly preferably> 0.2 % By weight to ⁇ 1.0% by weight of the iron (II) sulphate-containing reducing agent.
- the invention therefore provides that the iron (II) sulfate-containing reducing agent is added to the powdered cement before or after grinding and / or before and / or during filling into packaging, bulk containers and / or transport containers.
- iron (II) sulphate-containing reducing agent is added to the cement only when it is used, by adding the iron (II) sulphate-containing reducing agent to the cement while it is being mixed with water, immediately before and / or immediately afterwards is mixed.
- iron (II) sulfate-containing reducing agent can be carried out in solid form, according to another embodiment of the invention but also in the form of a solution and / or suspension.
- the iron (II) sulfate-containing reducing agent obtained according to the invention does not show the generally known ever decreasing reduction effect with increasing storage time, but again an increasing reduction effect.
- the reducing agent obtained and used according to the invention thus shows no significant decrease in the reducing action with increasing storage time, in particular not after one month.
- a further significant advantage of the invention is that the product to be used as a reducing agent is produced industrially at a constant cost and a simple and energy-saving process for recycling used sulfuric acid, whereby a product is formed which is used as a reducing agent for chromate in cement can.
- iron (II) sulphate-containing reducing agent with other reducing agents, for example with conventional green salt, may also be advantageous, so that the invention further provides that iron (II) sulphate-containing reducing agent obtained from the iron sulphate-containing dilute acid obtained in the titanium dioxide production after the sulphate process together and / or in admixture with green salt, which is recovered elsewhere, is added.
- the invention further proposes a preparation of cement and an iron (II) sulphate-containing reducing agent which is> 0.01% by weight to ⁇ 5% by weight, preferably> 0.1% by weight to ⁇ 3 % By weight, more preferably> 0.2% by weight to ⁇ 1.0% by weight of the iron (II) sulphate-containing reducing agent obtained by the process according to the invention.
- a preparation is provided which, based on cement, is> 0.01% by weight to ⁇ 5% by weight, preferably> 0.1% by weight to ⁇ 3% by weight, particularly preferably> 0.2% by weight to ⁇ 1, 0% by weight of the iron (II) sulphate-containing reducing agent.
- the Preparation also include water.
- the preparation additionally contains water and, based on cement, from> 0.01% by weight to ⁇ 5% by weight, preferably> 0.1% by weight to ⁇ 3% by weight, particularly preferably> 0, From 2% to ⁇ 1.5% by weight of the iron (II) sulphate reducing agent.
- the dilute acid obtained in the production of titanium dioxide by the sulphate process with a sulfuric acid content of 23.5% and 3.8% iron was reduced to a sulfuric acid content of 48% (corresponding to a sulfuric acid concentration in the liquid phase of 65%) in a three-stage forced circulation evaporator system with graduated increased vacuum. ) evaporated. During evaporation, a large part of the iron sulfate crystallizes out as a monohydrate. Thereafter, the resulting thick sludge was treated directly with metallic iron and then with ground CaCO 3 .
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Ceramic Engineering (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Materials Engineering (AREA)
- Structural Engineering (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Inorganic Compounds Of Heavy Metals (AREA)
- Curing Cements, Concrete, And Artificial Stone (AREA)
Abstract
Description
Claims
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE200410059047 DE102004059047B4 (de) | 2004-12-07 | 2004-12-07 | Verfahren zur Herstellung eines eisensulfhaltigen Reduktionsmittels und dessen Verwendung |
PCT/EP2005/012769 WO2006061127A1 (de) | 2004-12-07 | 2005-11-30 | Verfahren zur reduktion des löslichen chromatgehaltes in zement sowie eine zubereitung aus zement und wasserlöslichen metallsulfaten |
Publications (1)
Publication Number | Publication Date |
---|---|
EP1833764A1 true EP1833764A1 (de) | 2007-09-19 |
Family
ID=35734897
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP05813617A Withdrawn EP1833764A1 (de) | 2004-12-07 | 2005-11-30 | Verfahren zur reduktion des löslichen chromatgehaltes in zement sowie eine zubereitung aus zement und wasserlöslichen metallsulfaten |
Country Status (3)
Country | Link |
---|---|
EP (1) | EP1833764A1 (de) |
DE (1) | DE102004059047B4 (de) |
WO (1) | WO2006061127A1 (de) |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN102107911B (zh) * | 2011-03-04 | 2012-07-04 | 大连海事大学 | 溶液放电等离子体诱导铁泥还原制备硫酸亚铁的方法 |
ITMI20120764A1 (it) | 2012-05-07 | 2013-11-08 | Mapei Spa | Additivo per cemento portland costituito da un riducente incapsulato in una matrice polimerica |
Family Cites Families (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
ATE294148T1 (de) * | 2003-01-25 | 2005-05-15 | Alexander Kehrmann | Chromatreduziertes hydraulisches bindemittel |
DE20321107U1 (de) * | 2003-07-17 | 2005-12-15 | Kerr-Mcgee Pigments Gmbh | Zubereitung zur Reduktion des löslichen Chromatgehaltes in Zement |
DE50307965D1 (de) * | 2003-10-06 | 2007-09-27 | Kerr Mcgee Pigments Gmbh | Verfahren zur Aufarbeitung eisenbelasteter Gebrauchtschwefelsäure |
EP1559694A3 (de) * | 2004-01-27 | 2007-12-12 | Kronos International, Inc. | Pulverförmige Mischung, Verfahren zu ihrer Herstellung und ihre Verwendung zur Chromatreduktion in Zement |
-
2004
- 2004-12-07 DE DE200410059047 patent/DE102004059047B4/de not_active Expired - Fee Related
-
2005
- 2005-11-30 EP EP05813617A patent/EP1833764A1/de not_active Withdrawn
- 2005-11-30 WO PCT/EP2005/012769 patent/WO2006061127A1/de active Application Filing
Non-Patent Citations (1)
Title |
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See references of WO2006061127A1 * |
Also Published As
Publication number | Publication date |
---|---|
WO2006061127A1 (de) | 2006-06-15 |
DE102004059047A1 (de) | 2006-06-08 |
DE102004059047B4 (de) | 2007-10-31 |
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