Compositions: coating or plastic – Coating or plastic compositions – Inorganic settable ingredient containing
Patent
1990-05-14
1991-08-27
Dixon, Jr., William R.
Compositions: coating or plastic
Coating or plastic compositions
Inorganic settable ingredient containing
106750, 106766, C04B 702
Patent
active
050430203
DESCRIPTION:
BRIEF SUMMARY
Field of the Invention
The present invention relates to production of binding materials and, more particularly, to a method for production of portland clinker.
BACKGROUND OF THE INVENTION
At present, the portland clinker is produced from a finely disintegrated and homogenized mixture of limestone (55-60 mass %) and phosphoric slag (40-45 mass %). The ratio of components in said mixture of raw materials is determined by the saturation coefficient of clinker (SC): ##EQU1## i.e. by the degree of saturation of SiO.sub.2 to 3CaO.SiO.sub.2.
The prepared mixture of raw materials is calcined at 1350.degree.-1450.degree. C. until the oxidized calcium is fixed completely in the minerals of portland clinker. Then the produced portland clinker is subjected to forced air or water cooling (SU, A, 507537, 299475).
However, the produced clinker contains phosphorus oxide (phosphorus pentoxide P.sub.2 O.sub.5) in the form of a solid solution in clinker minerals which retards the setting time of cement and reduces compression strength from 15 to 20 MPa at the initial periods of hardening. This, then, leads to swelling and peeling of the exposed surfaces of fresh molded products in the course of their steaming.
There is another known method for production of portland clinker from a ground and homogenized mixture of crudes containing limestone, phosphoric slag and an aluminosilicate component by calcining (SU, A, 876580).
This partially reduces the swelling and peeling of fresh products in the course of steaming and raises their strength in the course of the first three days to 23 MPa.
Known in the prior art is a method for the production of portland clinker wherein a low-oxidizing medium at 1,450.degree. C. a mixture of crudes containing limestone, phosphoric slag and cinder produced by calcining of pyrite, is calcined at a following ratio of components, wt %;
______________________________________ limestone 53-58.7
phosphoric slag 36-44
cinder 2.1-6.6
______________________________________
clinker from phosphorus-containing slags", a thesis, Cement Research
Institute, 1964).
A disadvantage of this method lies in a low strength of cement after steaming (10-20 MPa) and destructive processes manifested by swelling and peeling of exposed surfaces after steaming of fresh molded products.
SUMMARY OF THE INVENTION
The main object of the present invention resides in providing adequate conditions for the formation of iron phosphides not creating solid solutions with clinker minerals thus developing a method for the production of portland clinker with higher strength of cement and eliminating the swelling of exposed surfaces of fresh molded cement products during wet-heat treatment.
This object is realized in the method for production of portland clinker comprising the preparation of a mixture of crudes based on limestone and phosphoric slag and calcining the mixture at 1350-1450.degree. C. to fix the calcium oxide into portland clinker minerals followed by forced cooling of the produced clinker wherein, according to the invention, the mixture of crudes containing 59.7-65.05 mass % of limestone, 32.83-39.07 mass % of phosphoric slag and 1.07-6.21 mass % of additions containing more than 40 mass % of iron oxide is calcined in a reducing gas medium containing more than 80 mass % of carbon monoxide.
Owing to the present invention the strength of phosphorus-containing cement produced on the basis of the herein-disclosed clinker increases after steaming from 10.0-20.0 to 28-38 MPa. Besides, the fresh moulding surfaces of the products made from such a cement are not swelled nor peeled.
DETAILED DESCRIPTION OF THE INVENTION
The other objects and advantages of the present invention will become clear from the following detailed description of the method for the production of portland clinker and examples of the same.
The portland clinker is produced, according to the disclosed invention, from a lime-containing compound (limestone), phosphoric slag and additions containing over 40 mass % of iron oxide.
Limestone is a dense
REFERENCES:
patent: 4220475 (1980-09-01), Tokar et al.
patent: 4224077 (1980-09-01), Olifer et al.
patent: 4255201 (1981-03-01), Nudelman et al.
Aldiyarov Bakhyt D.
Kurnikov Pavel B.
Lerke Pavel P.
Shnaider Valery V.
Terekhovich Stanislav V.
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