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
  • C04B7/00—Hydraulic cements
  • C04B7/24—Cements from oil shales, residues or waste other than slag
  • C04B7/28—Cements from oil shales, residues or waste other than slag from combustion residues, e.g. ashes or slags from waste incineration
• • 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
  • C04B7/00—Hydraulic cements
  • C04B7/24—Cements from oil shales, residues or waste other than slag
  • C04B7/30—Cements from oil shales, residues or waste other than slag from oil shale; from oil shale residues ; from lignite processing, e.g. using certain lignite fractions
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P40/00—Technologies relating to the processing of minerals
  • Y02P40/10—Production of cement, e.g. improving or optimising the production methods; Cement grinding

Definitions

• the present invention relates to a process for producing cement or cement substitutes on the basis of carbon-containing compounds with a carbon content of more than 10 wt-%, wherein the carbon-containing compounds are burnt in a furnace at a temperature of 750 to 900 0 C.
• carbon-containing compounds are used.
• oil shale frequently is used, which as a collective term designates those clayey rocks which contain bitumen or ultra-heavy oils.
• kerogen lies between 10 and 30 wt-%.
• combustion for instance is effected by fluidized-bed combustion. This provides for a very good heat exchange and thus a very homogeneous temperature profile over the entire fluidized bed.
• additives for further improvement of the material properties, it is for instance known from EP 0 727 398 B2, to incorporate additives into the product obtained by combustion.
• useful additives include calcium sulfate or calcium sulfoaluminate, but alumina, phosphonic acid derivatives and a number of polymers can also be used.
• An end product obtained in this way often exhibits attractive properties in terms of construction chemistry, in particular in its capacity as composite cement with short setting times.
• Temperature control frequently is effected by discharge of energy from the furnace by means of membrane walls or immersed heater surfaces, as they are described in DE 34 47 186 A1.
• the immersed heater surfaces are immersed into the fluidized bed of the furnace or of a separate fluidized-bed cooler and withdraw energy from the same by evaporating a condensate.
• the vapor produced can be utilized else- where for energy generation.
• the disadvantage of increased investment costs due to an increased number of components the contact of these heat-dissipating components with the hot solids, which leads to a fast wear of the cooling elements, is problematic above all.
• the fluidized bed is cooled locally, which can lead to a less homogeneous product.
• cement properties refer to the fact that it is a hydraulically acting binder in particular for mortar and concrete, which upon addition of water hardens in a volume- and water- stable way by hydration. Due to the admixture of these additional materials, the product output is increased with reference to the amount of high-carbon raw material used. In addition, material properties of the resulting product can be varied selectively.
• the carbon-containing material is oil shale, which has a high heating value. It is, however, also possible to use combustion residues such as ashes or soots, in particular also combustion residues from coal-fired power plants, with a comparatively high carbon content.
• the carbon content is more than 10 wt-%, preferably more than 15 wt-%, and particularly preferably more than 20 wt-%.
• Lignite as low-grade coal with a high moisture content of mostly more than 50 wt-% likewise is suitable for use in accordance with the invention as material to be calcined when producing cement or cement substitutes.
• the additional material is mixed with the material to be calcined, before it is introduced into the furnace together with the same, in accordance with a preferred aspect of the invention.
• a homogeneous mixture is introduced into the furnace, which also leads to a homogeneous temperature profile in the furnace.
• the furnace temperature can additionally be influenced by an attached closed-circuit cooling.
• the prevailing temperatures of the solids streams approximately correspond to those of the desired furnace temperature.
• the inert and low-heating-value material additionally introduced into the process can be introduced into the solid stream at a point of the cooling circuit which is located before, inside or after the cooler.
• clay is added, which in cement production is used as a naturally occurring raw material and has puzzolanic properties.
• burnt oil shale which particularly preferably was obtained as a residue of pulverized-fuel firing systems and usually has a residual carbon content of 2 to 5 wt-% or more.
• burnt oil shale Beside hydraulic proper- ties as a carrier of aluminate, silicate and iron oxide, the admixture of burnt oil shale provides for the disposal (recycling) of a waste product and therefore offers an economic advantage to a particular extent.
• Another preferred aspect of the invention relates to the addition of low-carbon combus- tion residues from coal-fired power plants, in particular the so-called bottom-ash, which have a similar composition as the burnt oil shale and likewise hydraulic properties. Even more than when using burnt oil shale , the disposal of a problematic waste material must be emphasized here, since such combustion residues currently are disposed of on disposal sites.
• the carbon content of these compounds is below 10 wt-%, preferably below 5 wt-%, and particularly preferably below 2.5 wt-%.
• Another preferred aspect of the invention includes the addition of limestone, whereby both the sulfur content is reduced, in that the limestone is calcined, and the calcium oxide formed subsequently reacts with sulfur oxides, and the binding capacity of the product can be increased.
• Another preferred aspect of the invention describes the addition of gypsum, which in the resulting end product acts as binding retarder.
• a development of the invention provides the addition of at least one of the admixed materials in the moist condition.
• the water content of this material is up to 25 wt-%, preferably up to 15 wt-%, and as a result of calcination and/or evaporation it leads to an additional output of energy from the furnace, whereby the amount of the admixed material can be decreased at the same time.
• the solids stream consisting of oil shale and the admixed additional material is heated before entering the furnace.
• other pretreatments such as a preheating of individual components also are conceivable.
• FIG. 1 schematically shows a plant for performing the process of the invention
• Fig. 2 shows the energy to be dissipated in dependence on the amount of inert material used (clay, moisture 20 wt-%).
• Fig. 1 schematically shows a plant for performing the process of the invention.
• oil shale and an inert and/or low-heating-value material with cement properties are mixed and then supplied to a fluidized-bed furnace 3, in which the mixture is burnt at a temperature of e.g. 800 0 C, via a supply conduit 2.
• Mixing can also be effected by jointly grinding or by an other type of pre-preparation.
• inert material e.g. moist clay is admixed to the oil shale, which is dried and calcined at the temperature generated in the furnace by the combustion of the organic components of the oil shale.
• the quantities of oil shale and clay introduced into the furnace are determined according the energy amount necessary for combustion, drying and calcination.
• the solids are withdrawn from the furnace 3 via a discharge conduit 4 and after possible further processing steps, such as grinding and mixing with cement clinker, are employed as cement and used for instance in the production of concrete.
• the solids Before or after mixing in the mixing tank 3, the solids can for instance be preheated in a Venturi preheater 5.
• a circulating fluidized bed instead of the illustrated stationary fluidized bed as furnace 3, a circulating fluidized bed, an annular fluidized bed, but also a rotary kiln or some other suitable furnace design can of course also be used for the combustion of the material.
• inert/low-heating-value materials like limestone, gypsum, burnt oil shale and/or combustion residues from power plants can be added. All these materials have cement properties in the sense of the present invention and can be employed as hydraulically acting binders.
• 16 t/h of oil shale with a moisture of 7 wt- % and an inlet temperature of 25 0 C are introduced into a furnace, e.g. a fluidized-bed furnace. Assuming a heating value of 3400 kJ/kg, a discharge of 4.3 MW is necessary, in order to keep the furnace temperature below the product-damaging temperature of 900 0 C.
• clay with a moisture content of 20 wt-% is admixed to the oil shale.
• the available amount of energy of 4.3 MW about 3200 kg/h of the clay can be dried and calcined in the furnace.
• Fig. 2 shows the decrease rate of energy to be discharged, which is present in the furnace, in dependence on the moist clay amount used for the assumed moisture content of 20 wt-%.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Ceramic Engineering (AREA)
• Materials Engineering (AREA)
• Structural Engineering (AREA)
• Organic Chemistry (AREA)
• Oil, Petroleum & Natural Gas (AREA)
• Combustion & Propulsion (AREA)
• Curing Cements, Concrete, And Artificial Stone (AREA)
• Processing Of Solid Wastes (AREA)
• Carbon And Carbon Compounds (AREA)
• Production Of Liquid Hydrocarbon Mixture For Refining Petroleum (AREA)

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• 2008
  • 2008-12-12 DE DE102008061743.1A patent/DE102008061743B4/de not_active Expired - Fee Related
• 2009
  • 2009-10-24 WO PCT/EP2009/007620 patent/WO2010066316A1/en active Application Filing
  • 2009-10-24 AU AU2009326594A patent/AU2009326594B2/en not_active Ceased
  • 2009-10-24 EA EA201190005A patent/EA018753B9/ru not_active IP Right Cessation
  • 2009-10-24 BR BRPI0923335-0A patent/BRPI0923335B1/pt not_active IP Right Cessation
  • 2009-10-24 UA UAA201105741A patent/UA103780C2/ru unknown
  • 2009-11-02 JO JOP/2009/0401A patent/JO2988B1/ar active

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