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
  • C04B7/14—Cements containing slag
  • C04B7/147—Metallurgical slag
  • C04B7/153—Mixtures thereof with other inorganic cementitious materials or other activators
  • C04B7/17—Mixtures thereof with other inorganic cementitious materials or other activators with calcium oxide containing activators
• • 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 invention relates to a process for the production of cement clinker.
• cement consists of a mixture of calcium oxide (CaO), silicon oxide (SiO 2 ) and aluminum oxide (Al 2 O 3) and optionally further additives such as magnesium oxide (MgO) and iron oxide (Fe 2 O 3), with sintering or firing of the processed raw materials in
• CaO calcium oxide
• SiO 2 silicon oxide
• Al 2 O 3 aluminum oxide
• MgO magnesium oxide
• Fe 2 O 3 iron oxide
• the properties of the cement clinker are mainly determined by the mass ratio of calcium oxide (CaO) and silicon oxide (SiO 2 ).
• cement clinker is energy-consuming. Much of the energy required for cement preparation is for the production of CaO from the natural raw material "limestone", the calcium carbonate (CaCO3) contains, by driving ( “calcining / deacidifying") of the CO 2 at 800 - requires 900 0 C. Therefore, a continuously increasing proportion of the energy consuming produced cement clinker, which is produced by sintering of CaO with SiO 2, and lesser amounts of Al 2 ⁇ 3, MgO and Fe 2 ⁇ 3 at 1400 0 C, replaced by granulated blast furnace slag with essentially the same components.
• blast furnace slag in particular has a lower Ca content, which lengthens the curing process of the cement clinker. Therefore, it can not be waived for sufficiently short curing times on the Ca richer and energy-intensive clinker to be produced.
• the object of the invention is to provide a method for the production of cement, in which the energy requirement is reduced.
• the integration of cement production with the formation of slag results in considerable advantages.
• the liquid blast furnace slag was cooled without using the heat content: This is done either slowly in the so-called slag bed to z. B. slag z. B. for road construction, or quickly by quenching with large amounts of water, so that the slag crumbles by internal tensions to a largely glassy granules, the so-called blastfurnace slag, which then goes in this form as a rakers replacement in cement production.
• blast furnace slag in the liquid state in particular is brought into contact with limestone powder, so that the calcination proceeds with the use of the slag's heat content If the heat transfer takes place by direct contact between slag and limestone flour, the released CO2 can on the one hand
• the powdered CaO can immediately form the cementitious compounds with the liquid slag without requiring an additional sintering process, thus enriching the slag with Ca without further energy consumption.
• blast furnace slag can be used for the process according to the invention also steel mill slag, as obtained in particular in electric furnace
• Figure 1 is a process scheme for the preparation of cement according to the prior art and Figure 2 shows the procedure in the invention.
• a rotary kiln (so-called “rotary kiln") is used, which is designated by 10 in Figure 1.
• the input of the rotary kiln 10 is a mixture of sand as the basis for silicon dioxide (SiO 2) and alumina as the basis for aluminum oxide (Al 2 O 3
• limestone containing calcium carbonate (CaCO 3) as a base for calcium oxide (CaO) is fed to the rotary kiln 10.
• Corresponding functional units are denoted by 11 and 12. Additions of other compounds containing magnesium (Mg), sodium (Na), potassium (K) and / or sulfur (S) are not discussed in detail.
• Calcinator is first a process called “deacidification” in practice, the so-called calcination, wherein the CO2 is expelled at a temperature between 600 and 1000 0 C. Subsequently, a sintering takes place at about 1450 ° C. To do this, the rotary kiln In this case, CO2 is normally released into the environment, with prior gas purification being required.
• the product of the rotary kiln 10 is the so-called clinker.
• clinker In the clinker, it depends significantly on the mass ratio of calcium oxide and silicon oxide, by the factor
• the clinker normally has an ⁇ > 2. Milling and subsequent mixing with the known additives takes place, in which case in particular the granules are fed to a slag produced in a blast-furnace process.
• the result of the process after mixing - even with small amounts of aggregates - is the cement intended for use in the construction industry, in particular, as mortar and / or concrete.
• the liquid slag 1 obtained in a conventional blast furnace process contains CaO, MgO, SiO 2 , Al 2 O 3 and FeOx, the factor ⁇ defined above lying between 1 and 1.5.
• water cooling has hitherto been carried out in accordance with reference numbers. to win blastfurnace slag. Subsequently, the ashes are ground with the clinker, as already described in detail above.
• powdered CaO is added to the slag in the molten state in order to increase the factor ⁇ .
• at least a portion of the limestone powder is first heated and deacidified by the waste heat of the formed and finally to about 100 0 C as a cooling Klinkens.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Ceramic Engineering (AREA)
• Inorganic Chemistry (AREA)
• Materials Engineering (AREA)
• Structural Engineering (AREA)
• Organic Chemistry (AREA)
• Silicates, Zeolites, And Molecular Sieves (AREA)
• Processing Of Solid Wastes (AREA)

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Citations (6)

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• 2008
  • 2008-11-21 DE DE102008058573A patent/DE102008058573A1/de not_active Withdrawn
• 2009
  • 2009-11-12 WO PCT/EP2009/065039 patent/WO2010057825A1/de active Application Filing

Patent Citations (6)

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