Compositions: coating or plastic – Coating or plastic compositions – Inorganic settable ingredient containing
Reexamination Certificate
1996-02-12
2002-05-21
Marcantoni, Paul (Department: 1755)
Compositions: coating or plastic
Coating or plastic compositions
Inorganic settable ingredient containing
C106S745000, C106S755000, C106S758000
Reexamination Certificate
active
06391107
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a method for the combined utilization of residual materials which are fed to the rotary drum kiln in processed form with the raw powder during the production of cement and sulfuric acid according to the so-called Müller-Kühne process and are split off by using chemically reactive carbon which also consists partially of residual materials, at a temperature of over 700° C. with the calcium sulfate, whereby the CaO is then calcined at a temperature of over 1,200° C. in the presence of SiO
2
, Al
2
O
3
, and Fe
2
O
3
into cement, and the SO
2
-containing flue gas is freed from dust, washed, mixed with air, and converted to SO
3
or H
2
SO
4
. The invention relates also to an installation for performing said method which comprises a comminution device for the raw powder components, silos, drying drums, a final comminution device, the raw powder silo, the rotary drum kiln, the burner with burner pipe, the clinker discharge and the cement processor, the flue gas discharge chamber, the deduster, the flue gas washer, and the H
2
SO
4
plant.
The Müller-Kühne process is based on a reducing splitting-off of calcium sulfate at temperatures of over 700° C. using carbon. The calcium sulfite, which forms as an intermediary product, reacts with the excess calcium sulfate to form calcium oxide and sulfur dioxide. The cement clinker which forms during the calcination of the CaO essentially consists of tricalcium silicate, dicalcium silicate, tricalcium aluminate, and tetracalcium aluminate ferrite. The starting material for the classic process consisted essentially of the natural materials anhydride, coke, raw clay, raw sand, gravel, roasting residue, gypsum, and brown coal dust. The moist starting materials were dried, dosed by weight, and then comminuted and mixed in a ball mill. The resulting raw powder is fed into a slightly angled rotary drum kiln and passes through the latter in counterstream to the combustion gas whereby, as a rule, brown coal dust was used. This classic gypsum sulfuric acid process is economically inferior to standard cement production processes. The economy of the process can be improved, however, by utilizing residual materials from other production processes, which are problematic to store. The substitution of the traditional natural raw materials and primary energy medium, that is, brown coal, with suitable residual materials which can be utilized materially and/or energetically is a significant advantage (Chemische Rundschau No. 38, Sep. 24, 1993, p. 11). A great variety of residual materials has been tested, for example, waste gypsum, waste lime, waste sulfuric acid, acid tars, acid resins, brown coal filter ash, construction debris, used porcelains, podsol, and many others. The disadvantage is that the corresponding raw powder components, but also the fuel components, exert a different influence on the process and final products, that is, as well on the cement as on the sulfuric acid and oleum. In addition, this also does not provide for a consistent process control, especially since the following operating stages, such as, for example, dedusting and gas processing, are greatly influenced in their effectivity by the composition of the starting materials.
The invention is thus based on the objective of further developing the Müller-Kühne process and create an installation in a manner so as to enable a further protection of the resources, on the one hand, and landfill space, on the other hand, while observing and meeting environmental regulations and economy.
SUMMARY OF THE INVENTION
According to the invention, this objective is realized in that the raw powder components and the fuel components, which include the residual materials to be used, including the compensation and reaction substances required for eliminating components untypical for cement, are stored separately, conditioned, and are then added in accordance with the specified formulation and monitored by way of sampling and sample evaluation; the liquid and solid residual materials to be used as fuel are transported separately to the rotary drum kiln and are then burned with a mutually supportive flame; and the flue gases of the kiln hood and the fuel gas discharge chamber are flash-cooled by feeding in cooling gas.
The incoming residual materials are, like the remaining raw powder and fuel components, stored separately and are then added to the process comminuted and homogenized according to the respective formulation and mixed with each other. The fact that the individual starting products have been previously tested and are also being tested during and following their being mixed, makes it possible to always make available and add a starting product which corresponds exactly to the specified formulation and thus to an optimum process. As needed, compensation and reaction materials are added in order to eliminate components untypical for cement, said materials resulting in a recombustion of trace contaminants, for example, in the rough dust chamber, in order to prevent obstacles in the process further on or problems in regard to the clinker. This ensures a continuously consistent process, even though a great variety of materials and also in changing compositions, are used. By forming corresponding buffers, any difference over time can be compensated, so that, for example, products accumulating in different amounts due to seasonal circumstances can also be available in optimum amounts and can be added accordingly. In addition to large accumulation amounts which, however, also must be combined according to material groups of a similar composition, there are a number of valuable concentration products for CaO, SiO
2
, Al
2
O
3
and Fe
2
O
3
which are collected and kept available for formulation corrections. By intermediate sampling additional knowledge is obtained which results in possibilities for correcting the raw powder product. An adequate analysis speed hereby can be ensured, in particular in that the analysis method is changed away from molten product to the “prepared tablet”. This continuous accompanying analysis makes it possible to advantageously compensate for the high dispersion or band latitude of the starting base of the raw powder. By adjusting the raw powder, the kiln operation and the produced clinker can be made more uniform. This ensures an improvement regarding the certain reproducibility of the clinker, and thus the certain predetermination of the cement quality. The combined addition of the various fuel components into the rotary drum kiln and the partially inter-supporting combustion ensure that a flame which is advantageous for the conversion process is always available. In particular, this also provides the possibility to completely eliminate solid fuel, such as coal, for longer periods and to use, instead, residual fuel materials, such as, for example, wood chips and saw dust saturated with residual materials, ensuring an advantageously uniform flame. The long flame, which is formed, for example, when saw dust is burned, is advantageously supported by the short flame of the solvent and the high-energy and hot flame of the old oil, as well as of the acid tar and acid resin. The flame reaches far into the rotary drum kiln and thus is able to make a safe contribution to an advantageous burning process. The quenching of the flue gases and the fact that the kiln hood and flue gas discharge chamber are sealed advantageously prevents damaging alkali precipitations. In addition, this feeding-in of cooling gas generates a vacuum with an advantageous effect on the entire burning process. This withdrawal of the flue gas manifests itself up to the area of the clinker discharge. The greater amount of flue gas flowing through the rotary drum kiln per time unit ensures optimum combustion of the residual materials. The sealing of the kiln hood hereby ensures that this suction for the flue gas acts far into the rotary drum kiln without drawing in secondary air at wrong places.
According to a useful embodiment of the invention, it is provided
Meininger Siegfried
Reimann Götz
Reimann Hanno
Creighton Wray James
E. Schwenk Baustoffwerke KG
Marcantoni Paul
Narasimhan Meera P.
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