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
  • 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
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F1/00—Treatment of water, waste water, or sewage
  • C02F1/52—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities
  • C02F1/5272—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities using specific organic precipitants
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F1/00—Treatment of water, waste water, or sewage
  • C02F1/70—Treatment of water, waste water, or sewage by reduction
  • C02F1/705—Reduction by metals
• • 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
  • 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
  • C04B5/00—Treatment of  metallurgical  slag ; Artificial stone from molten  metallurgical  slag 
  • C04B5/06—Ingredients, other than water, added to the molten slag or to the granulating medium or before remelting; Treatment with gases or gas generating compounds, e.g. to obtain porous slag
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F2101/00—Nature of the contaminant
  • C02F2101/10—Inorganic compounds
  • C02F2101/20—Heavy metals or heavy metal compounds
  • C02F2101/22—Chromium or chromium compounds, e.g. chromates
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
  • C02F2103/06—Contaminated groundwater or leachate
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
  • C02F2103/10—Nature of the water, waste water, sewage or sludge to be treated from quarries or from mining activities
• • 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 additives for Cr (Vl) or Cr 6+ reduction.
• the invention relates to additives for Cr (Vl) reduction in cement, cement bricks, cement mortars, cement blocks, concrete, cementitious products, slags, mining industry waste and, industrial wastewater.
• Cr (Vl) is a known carcinogen often present in cement compositions which remains present for years or even decades after the cement has been used in construction of buildings.
• level of Cr (Vl) in cement and cementitious products is legislated and cement producers around the world have considered as to how to reduce the amount of Cr (Vl) in cement either during production thereof or during preparation of cementitious products from the cement.
• US Patent 7,232,483 provides compositions and methods for reducing hexavalent chromium in cementitious compositions involving the use of a liquid additive composition, comprising stannous chloride.
• a liquid additive composition comprising stannous chloride.
• the stannous chloride may be used at least one co-additive comprising an antioxidant, oxygen scavenger, or mixture thereof, and/or at least one agent comprising a cement grinding aid, cement quality improver, or mixture thereof.
• US Patent 6,872,247 in which methods and compositions involving hexavalent chromate-reducing agents, particularly hydroxylamine, hydrazine, or their salts or derivatives, for use in cement compositions and cement processing are disclosed.
• the present invention provides novel methods and compositions capable of reducing the hexavalent Chromium (Cr 6+ ) in cement, cement based products, concrete, fly ash, silica fume, waste water and mine residues, slags and particularly ferro - chromium slags.
• a Cr (Vl) or Cr 6+ reduction additive composition for use in cement, cement based products, slags, and wastewater which compositions includes NaNO 2 alone, ZnSO 4 .7H 2 O alone or, a combination of both and other chemical compounds.
• Chemical compounds containing the element N in the form of a simple or composed anion may be selected from N “ , N 2"1 N 3" , (NO 2 ) “ , (NO 2 ) 2" ,(NO 2 ) 3" , or the like.
• the additive composition when used for cementitious applications may contain from 0.01% to 1% of NaNO 2 by mass of cement. In other applications, the NaNO 2 and ZnSO 4 .7H 2 O dosage may be increased up to 5% wt.
• the additives may reduce the levels of hexavalent chromium Cr 6+ to less than 1 ppm, typically below 2 ppm.
• the above additives may include one or more anions of the element N, in simple or complex forms.
• the additives may include one or more organic salts of Na and Ca, for example, Ca (CH 3 COO) 2 , andCH 3 COO-Na.
• the additives may include a combination, in any proportions, of one or more of metallic Zn, metallic Mn, metallic Fe, Metallic Mg, metallic Sn powders with NaNO 2 , for example Zn+NaNO 2 , Fe+NaNO 2 , Mg+NaNO 2) Sn+NaNO2.
• the additives may include a combination, in any proportions, of any of the above compositions with any type of cement grinding aid, for example, acetic acid or acetates, gluconic acid or gluconates, ethanolamine, di-ethanolamine (DEA), tri-ethanolamine (TEA), tri- Iso-propanolamine (TIPA) or any other amine-based grinding aid.
• any type of cement grinding aid for example, acetic acid or acetates, gluconic acid or gluconates, ethanolamine, di-ethanolamine (DEA), tri-ethanolamine (TEA), tri- Iso-propanolamine (TIPA) or any other amine-based grinding aid.
• the additives may include the combination, in any proportions, of any of the above compositions, with any cement set and/or hardening accelerators based on or containing any of the chemical elements of Group IA and Group MA of the Periodic Table of Chemical Elements, for example, Ca (HCOO) 2 , Ca (NO 3 ) 2 , CaCI 2 , CaCO 3 , Ca 2 (NO 2 J 2 , LiNO 3 , Li 2 CO 3 , NaCI, KCI, Na 2 CO 3 , BaCI2, Ba(NO 3 J 2 , and MgCI 2 .
• any cement set and/or hardening accelerators based on or containing any of the chemical elements of Group IA and Group MA of the Periodic Table of Chemical Elements, for example, Ca (HCOO) 2 , Ca (NO 3 ) 2 , CaCI 2 , CaCO 3 , Ca 2 (NO 2 J 2 , LiNO 3 , Li 2 CO 3 , NaCI, KCI, Na 2 CO 3 , BaCI2, Ba(NO 3 J 2
• the additive may include combinations of any of the above compositions with any other reducing agents, organic or inorganic such as ascorbic acid or salt, oxalic acid or salt, FeSO 4 , MnSO 4 , SnCI 2 , SnSO4 in any crystal log raphic forms, Ca(CH3COO) 2 , Mg(CH3COO) 2 , Al 0 , Fe 0 , Mg 0 , Mn 0 and Sn 0 .
• any other reducing agents organic or inorganic such as ascorbic acid or salt, oxalic acid or salt, FeSO 4 , MnSO 4 , SnCI 2 , SnSO4 in any crystal log raphic forms, Ca(CH3COO) 2 , Mg(CH3COO) 2 , Al 0 , Fe 0 , Mg 0 , Mn 0 and Sn 0 .
• the additives may include combinations of any of the above compositions with any concrete admixtures ⁇ for example, lignosulphonate, polynaphthalene, polymelamine, polycarboxylate, polyacrylic, polyester, retarders, anti-shrinkage, anti-washout, anti- alkali silica reaction agents, viscosity modifying agents, or their combinations.
• NaNO 2 and ZnSO 4 .2H 2 0 are more cost-effective and, easier to handle in cement, slag, silica fume, concrete, building materials, in construction, and road & mining industries as they do not require any preliminary granulation or crystallization like the currently used FeSO 4 .7H 2 0 and MnSO 4 .7H 2 O reducing agents.
• the additives containing NaNO 2 may be safely used for wastewater treatment containing large amounts of Cr 6+ at any pH, and in soils and mining industry waste. It may be used in liquid or powder form, alone or in combination with other reducing agents.
• the new compositions can be added in the form of aqueous solution which are easier to dispense in cement or concrete making when compared to Sn, Mn or Fe-based agents.
• the invention extends to pre-blends, in any proportions, of any of the additive compositions disclosed above, with any cement, slag, limestone powder, silica fume, fly ash, clays, pozzolanas, dry mortar, and/or combinations thereof.
• the invention extends to cementitious compositions and products thereof, which include additive compositions as described above, added in any form, whether liquid, powder or crystal form, after, before, or together with the addition of mixing water thereto.
• the cementitious compositions may be used for production of cement-based bricks, blocks, mortars, or concrete.
• the invention extends to the addition of one or more additive compositions described above to clinker before or during its milling process, in liquid or powder form.
• NaNO 2 and similar agents have the particular ability of reducing high amount of Cr(VI) e.g. IOOOppm Cr(VI) in water and at any pH.
• Cr 3+ containing products are insoluble in water and are not carcinogenic. It is probable that water soluble Zn salts form insoluble complex compounds in presence of Cr 6+ at alkaline pH.
• the potentially new complexes might not release Cr 6+ back in the original products as effect of age and/or temperature like the commonly used Iron sulfate.
• the additives prevented oxidation back to Cr 6+ in the treated cements for 9 weeks at 40 0 C.
• the additive may include Zn powder and organic salts of Zn, for example, Zn (CH 3 COO) 2 ..
• Figure 1 shows the amount in ppm of Cr 6+ reduced in Ordinary Portland cement (CEM I) samples with different Cr 6+ contents when NaNO 2 is added to the cement. Reduction in CEM I containing 10ppm Cr(VI)
• Figure 2 shows the ppm, rate of Cr 6+ reduction in the Ordinary Portland cement (CEM I) samples containing different amounts of Cr 6+ when NaNO 2 is added to the cement.
• the first bar of each set shows the reduction in CEM I containing 10 ppm Cr(VI)
• the second bar shows the reduction in CEM I containing 20 ppm Cr(VI)
• the third bar shows the reduction in CEM I containing 30 ppm Cr(VI).
• Figure 3 shows the effect of NaNO 2 on Ordinary Portland cement strength development when NaNO 2 is added to the cement.
• the first bar of each set shows a reference CEM I
• the second bar shows CEM I containing 0.05 wt% NaNO 2
• the third bar shows CEM I containing 0.1 wt% NaNO 2
• the fourth bar shows CEM I containing 0.2 wt% NaNO 2 .
• FIG 4 shows the effect of NaNO 2 on concrete slump retention
• Figure 5 shows the effect of the mode of addition of NaNO 2 on Cr (Vl) reduction in cement.
• the amount of reduction is not influenced by mode of addition.
• the first bar of a pair is the amount of Cr(VI) present in the cement and the second bar of the pair is the amount by which the Cr(V)) has been reduced in the cement.
• Figure 6 shows the effect of age and temperature on the amount of Cr(VI) reduction by NaNO2. Cr(VI) reduction at 40 0 C
• Fig 6 Effect of age and temperature on the amount of Cr(VI) reduction by NaNO2.
• Figure 7 shows the effect of pH on the amount of Cr (Vl) reduced by NaNO 2 .
• the first bar of each set shows the % reduction from a 100 ppm Cr(VI) aq.sol
• the second bar shows the % reduction from a 250 ppm Cr(VI) aq.sol
• the third bar shows the % reduction from a 500 ppm Cr(VI) aq.sol
• the fourth bar shows the % reduction from a 1000 ppm Cr(VI) aq.sol.
• Figure 10 shows the reduction of Cr 6+ in Ordinary Portland cement by the addition of different types of Zinc salts and Zinc oxide.
• Figure 11 shows the reduction of Cr 6+ in Ordinary Portland cement samples containing different amount of initial Cr 6+ by the addition of Zinc sulfate Heptahydrate.
• Figure 13 shows the reduction of Cr 6+ by the addition of Zinc sulfate Heptahydrate to a sample of Ordinary Portland Cement containing 5.5ppm Cr 6+ .
• Figure 14 shows the reduction of Cr 6+ in Ordinary Portland cement by the addition of a combination of Zinc sulfate Heptahydrate and Triethanolamine (TEA).

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Ceramic Engineering (AREA)
• Organic Chemistry (AREA)
• Materials Engineering (AREA)
• Structural Engineering (AREA)
• Life Sciences & Earth Sciences (AREA)
• Hydrology & Water Resources (AREA)
• Environmental & Geological Engineering (AREA)
• Water Supply & Treatment (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Inorganic Chemistry (AREA)
• Curing Cements, Concrete, And Artificial Stone (AREA)
• Processing Of Solid Wastes (AREA)

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• 2009
  • 2009-10-28 EP EP09827001.0A patent/EP2364281A4/de not_active Withdrawn
  • 2009-10-28 WO PCT/ZA2009/000094 patent/WO2010057225A2/en not_active Ceased

Non-Patent Citations (1)

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