CH646123A5 - Portland cement clinkers and process for their preparation - Google Patents

Description

The invention relates to a Portland cement clinker in which a setting regulator component is incorporated; it also relates to a process for the manufacture of such a clinker and its use.

In addition to properties such as mechanical resistance to compression and its good condition, the duration of the setting time of a given cement is also a property of great practical importance. In fact, the duration of the setting time should not be so short as to prevent the correct placement of the cement and the subsequent good finishing of its surface. Furthermore, if setting is too slow, it may result in undesirable sedimentation of the solids of the concrete, leading to sweating of water and from the concrete; in addition, the delay may be unacceptable to the user if it compromises the completion of the construction work in progress.

It is standard practice, in the manufacture of Portland cement, to incorporate therein at the time of grinding a small proportion of a source of sulphate, such as gypsum or anhydrite, which is added to the clinker in order to control the reaction between the final cement powder and water. By this means, we master the setting characteristics to the degree necessary to facilitate the placement of mortar or concrete.

There are, however, problems associated with the use of sulfate, particularly gypsum, added in this manner. One of them is the variability of the raw materials containing sulfate. Another is the occurrence of false setting reactions due to dehydration of the gypsum at normal grinding temperatures of a clinker to prepare the cement powder. The resulting hemihydrate can react with water to form crystallized gypsum, the precipitation of which has an unfavorable effect on the rheology of the concrete mixture, which makes it necessary to add more water to produce a mixture having workability. suitable. This additional water has an adverse effect on the quality and useful life of the concrete. Although the problem of a false setting can be overcome by prolonging the work, it is frequent that this leads to troublesome requirements with regard to the demand for cement in water, the final consequence being a reduction in the quality of the mortar or concrete. The construction of larger crushing plants, operating at higher crushing temperatures, required the use of more complex and costly cooling systems to alleviate the severity of this problem.

Another problem may arise in the case of clinkers containing an appreciable amount of potassium sulphate (K2SO4). When ground with gypsum, potassium sulphate can react with gypsum (CaS04 • 2H20) to form syngenite (K2S04 • CaS04 • H20) which causes an air intake, the result being that the cement s agglomerate in clusters, giving it poor flow characteristics. Such agglomerated cement is difficult to mix with aggregates to form a homogeneous mixture, and this leads to obtaining a mortar of poor quality.

Another problem is that of the flash plug. It is well known, in fact, that the tricalcium aluminate (designated by the abbreviation C3A where C represents CaO and A represents A1203), a component of cement, undergoes a rapid reaction on contact with water. It is believed that adding sulfate to the cement clinker results in the formation of an ettringite layer on the C3 A domains, this layer regulating the setting reaction. However, when the proportion of sulfate is insufficient to delay the hydration of the C3 A phase, a flash can occur. This is almost irreversible because, if we try to break the grip and rework the mixture, we finally get a concrete whose quality is very significantly reduced.

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An essential object of the present invention is to eliminate or alleviate the abovementioned problems by producing a Portland cement clinker comprising a setting regulator, this component fulfilling the role played hitherto by gypsum or another sulfate added to the clinker after cooking. In other words, a retarding component which confers improved setting properties, of the self-regulating type, is incorporated into the clinker to the cement prepared from the clinker.

Specialists are well aware that SO 3 present in the form of calcium sulphate such as anhydrite calcined to death in a Portland cement clinker (substance different from calcium sulphate added later to the clinker) is ineffective as a retarder, because of its slow dissolution in the mixing water. It is also known that the more easily soluble alkali metal sulfates are poor retarders and, moreover, favor the establishment of good values of the mechanical resistance of concrete shortly after setting, but this at the expense of the final values. of this resistance.

The subject of the invention is a Portland cement clinker comprising, as a component incorporated into said clinker and serving as setting regulator: a) sulfate, in the presence of alkali metal in the combined state, and / or b) l halogen in the combined state, said setting regulating component being present in a sufficient proportion to prevent premature setting of the cement produced from said clinker.

The invention also relates to a process for the manufacture of such a clinker, which process is characterized in that it consists essentially in heating until partial melting a mixture of materials containing mainly lime (CaO) and silica (Si02) with a smaller proportion of alumina (A1203) and iron oxide (Fe203), in the presence of: a) a material containing sulfur and a material containing alkali metal, and / or in the presence b) a material containing halogen, under conditions such that sufficient sulphate and alkali metal and / or halogen are retained inside the clinker to prevent premature setting of the cement produced from this clinker.

Cement can be obtained by spraying or grinding the clinker in question, and this can be done using conventional methods and using conventional equipment. However, in order to fully obtain the advantages which can be acquired by implementing the present invention, it is considered preferable for the clinker to be ground in the substantial absence of the addition of a sulfate such as than gypsum or anhydrite.

At least a portion of the elements necessary to form the setting regulating component in the clinker may already be present in the raw materials for the manufacture of cement, or else may be introduced into the furnace by the fuel used to heat it. However, the process normally involves the introduction, into the oven, of one or more addition agents providing halogen and / or sulfur and alkali metal. Of course, it should be borne in mind that any reference, in the course of the present description and of the following claims, to a halogen or to an alkali metal must be understood as normally designating the element in a combined state, such as the halide ion or the alkali metal ion, respectively. Likewise, the reference to sulfur should be understood to include sulfur in a combined form, usually as sulfate. The additives can be introduced into the furnace either separately or together, by incorporating them into the feed comprising the raw materials for making cement, or by using any other method such as insufflation.

The sulfur source, other than that which can be derived from the main raw materials and the fuel, is preferably chosen from calcium sulphate, calcium sulphate hydrates, alkali metal sulphates, double alkali metal and calcium sulphates , and mixtures of at least any two of these substances. More particularly preferred sources are gypsum, potassium sulfate, and cement precipitator dust rich in potassium and sulfur.

Preferred sources of alkali metal compounds are the primary feedstocks or the fuel or additions of alkali metal sulfate or double alkali metal sulfate and calcium discussed above. The preferred alkali metal is potassium, although sodium may also be commonly present.

The preferred halogen is fluorine. The source of fluorine, other than that which may be found in the main raw materials, is preferably calcium fluoride.

As can be seen from the above, the use of sulfate as an incorporated setting regulator requires the presence, inside the clinker, of alkali metal; however, with sufficiently high sulphate contents, it suffices that the halogen (in particular fluorine) is present only in a small proportion, and it can even be completely absent in appropriate cases. Conversely, when halogen (in particular fluorine) is used as setting regulator at sufficiently high contents, the sulphate and the alkali metal can be present only in small proportions and can also, in some cases, be completely absent '.

However, it is considered preferable that the clinker contains both halogen and sulfate, in the presence of an alkali metal. The halogen and sulfur introduced into the oven exert a combined mineralizing action which allows the combination of the raw materials to intervene in the oven at lower baking temperatures, which therefore facilitates, in particular in low-efficiency ovens thermal, the desired retention of sulphate and alkali metal in the clinker at the levels required for the setting regulation action. Halogen, in particular fluorine, also exerts a retarding effect which helps to exercise good control of the setting.

The halogen used as setting agent is generally present in the clinker in a proportion, measured in halide, representing by weight from 0.01 to 1%, preferably from 0.1 to 1%, and even more advantageously from 0 , 15 to 0.30% of the weight of the clinker.

The proportion of alkali metal is normally measured as oxide. In general, the alkali metal content of the clinker expressed in equivalent Na 2 O is, by weight, from 0.1 to 3%, preferably from 0.4 to 2.0%, and more advantageously still from 0.60 to 1, 0% of the weight of the clinker.

For the purposes of the invention, the minimum clinker sulfate content is determined by the expression: minimum weight% of SO 3 = (Na 2 O equivalent in the clinker by weight x 1.29) + 0.2%. This minimum required SO 3 content is sufficient for all of the alkali metal oxide to be in the form of sulfate, together with a small proportion of calcium sulfate. This calcium sulfate and potassium sulfate will in turn combine to form the double sulfate, known as calcium langbeinite.

The numerical value calculated in any given case from the preceding expression is hereinafter simply specified, for convenience, as relating to the minimum clinker sulfate. Preferably, it is not less than 0.33%.

To avoid problems of volume instability of the cement, the upper limit of SO 3 in the clinker is normally 5.0% by weight. The preferred range of SO 3 content ranges from 2.0 to 4.0% by weight.

When the setting regulator is wholly or partly sulphate, it is found that the presence, in the clinker, of a double sulphate of alkali metal and of calcium, more especially of potassium sulphate and calcium (calcium langbeinite), is particularly advantageous.

The C3A phase content of the clinker is related to two chemical parameters, namely the silica ratio and the alumina ratio (the calculation of these ratios being described below). In general, at a given alumina ratio, a decrease in the implied silica ratio

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than an increase in the C3A content. Since C3A reacts quickly with water, one would expect that the intake of cements produced from clinkers with high C3A contents would be more difficult to control. We were however surprised to find that the present invention still provides excellent setting regulation even with cements produced from clinkers having silica ratios of 2.80 and less.

On the other hand, a good control of the setting is achievable even with a content of the clinker in C3A greater than 5% by weight.

A suitable choice and regulation of the proportions of the setting regulating components, and a control of the cooking by methods recognized in principle as allowing the retention of the required proportions of these components in the clinker produced, in particular in the form of easily soluble sulfate , make it possible to obtain from the clinker a cement having well regulated setting properties, avoiding the need to add a sulphate, such as gypsum, to the clinker during its grinding. The addition of additional sulfate can be made unnecessary by the invention, but is not excluded; such an addition may prove to be advantageous for providing a fine adjustment of the setting characteristics of the cement. In the absence of gypsum or the like, grinding can be carried out hot without detrimental effects on the quality of the cement, which avoids the need to resort to an expensive cooling apparatus.

Therefore, by allowing the clinker to be ground without additional gypsum, it becomes possible to avoid the problem of a false hold. In addition, the presence of a regulator incorporated in the clinker inhibits the flash setting. It will be noted that, by grinding in the absence of gypsum, the problem of air intake due to the formation of syngenite is avoided. On the other hand, even if it is necessary to add a little gypsum during grinding, when easily formed calcium langbeinite is formed during the clinker production operation, this decreases the proportion of potassium sulphate which, without it, would be available to form syngenite.

Another advantage of the invention is that low quality gypsum and by-product gypsum normally considered as unusable as retarders when they are ground with a Portland cement clinker can nevertheless be used as a source of sulphate during the implementation of the present invention.

Yet another advantage is that materials (diluents) such as slag, fly ash or pozzolan can be incorporated by clinker grinding according to the invention, allowing the implementation of a hot grinding process to produce a charged cement without no harmful effect on the properties of this cement. Such diluents or fillers can also be ground separately and then mixed with the separately ground clinker. Thus, it becomes possible to produce a wide range of diluted or loaded Portland type cements, advantageously produced from the clinker obtained in accordance with the invention using an adequate diluent.

The clinker which is the subject of the invention can be ground to form a cement of any desired degree of fineness. However, the specific surface of the cement should not normally be less than 225 m2 / kg.

In general, the proportion of the setting regulating component is chosen so that the duration of the initial setting time is not less than 45 min (according to British standard BS 12: 1978) and, preferably, is not less than 60 mins. The duration of the final setting time should not normally be more than 10 h. The durations of the initial setting time for cements of typical production are commonly between 90 and 220 min, while the durations of the final setting times for such cements are commonly between 150 and 300 min.

The present invention is illustrated by the following examples, which are of course not limiting, in which the proportions and quantities expressed in percentages (%), in parts (p) and in ratios must be understood by weight, unless otherwise specified. The chemical parameters of the clinker, namely the lime saturation factor (LSF), the silica ratio (S / R) and the alumina ratio (A / F) are defined by the following expressions:

CaO - 0.7 S03

2.8 SÌO2 + 1.2 A1203 0.65 Fe203

S / R = ^ 2

A1203 + Fe203

however, the C3A content can be calculated using the expression:

C3A = 2.65 A1203 - 1.69 Fe203

in which each chemical symbol represents the percentage by weight of the identified substance present in the composition under consideration. The percentages of the oxides are as determined by the methods described in the British standard BS4550: Part 2: 1970.

The free lime contents are determined by the method of extraction with hot ethylene glycol.

The developed surface or specific surface is as determined by the method described in the British standard BS4550:

Part 3: section 3.3: 1978.

The durations of setting times are determined by the methods also described in BS4550: Part 3: sections 3.5 and 3.6: 1978.

Agglomeration or slip tests are carried out according to standard BS1881: Part 2: 1970. The numerical value for this test constitutes an indication of the workability of the composition in question, a value of 40 mm being considered as acceptable, and a value of 50 mm being considered as good.

Example 1:

The raw materials used are a mixture A of limestone / shale / sand, normal raw material for cement works, together with shale B and gypsum C, the analyzes of which are given below:

AT (%)

B (%)

VS(%)

SÌ02

13.7

55.3

0.7

A1203

3.8

21.2

0.19

Fe203

1.5

8.6

0.15

CaO

43.1

0.6

32.4

S (calculated in S03)

0.10

0.03

46.4

Loss on calcination

35.1

5.2

20.2

K2O

0.93

4.8

0.02

Na20

0.15

0.54

0.02

Calcium fluoride (CaF2) is also used, a reactive quality for general use.

The raw materials are mixed together in the following approximate proportions: 93.2% of A, 0.2% of B, 6.1% of C, plus 0.5% of CaF2. The mixture is ground until it leaves only a 9.5% residue on a 90 µ mesh screen.

Water is incorporated into the resulting raw mixture and formed into briquettes which are dried completely and then baked at 1400 ° C to produce a clinker which appears to contain 2.6% free lime and which has , in oxides, the following composition (%):

Si02

19.6

ai2o3

5.6

Fe203

2.3

CaO

65.1

so3

3.6

k2o

1.1

Na20

<0.1

F

0.28

(calculated as fluoride)

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The LSF is 0.99, the S / R is 2.48, and the A / F is 2.43. The C3A content of the clinker is calculated to be 10.9%. The content of Na 2 O equivalent is 0.83%, and the minimum clinker sulfate, calculated from this Na 2 O content, is found to be 1.27%.

The clinker is ground, without incorporating any addition, in a ball mill at 115 ° C to produce a cement having a. specific surface of 296 m2 / kg.

An agglomeration or slip test on this cement gives a value of 43 mm.

When determining the durations of its setting times, it is found that this cement has an initial setting duration of 230 min and a final setting duration of 290 min.

Example 2:

The raw materials, specified in Example 1, are mixed in the proportions corresponding approximately to 93.7% of A, 0.2% of B and 6.1% of C, then the mixture is ground to obtain a powder leaving a residue of 9.2% stfftun 90 mesh screen. With this composition, briquettes are molded which, after drying, are cooked at 1400 ° C to form a clinker whose free lime content is found to be 2.8% and which has the following composition, calculated as oxides (%) :

Si02

19.9

ai2o3

5.5

Fe203

2.2

CaO

65.5

so3

3.4

k2o

1.2

Na20

<0.1

F

0.03

The LSF is 0.99, the S / R is 2.58, and the A / F is 2.50. The C3A content is calculated to be 10.8%. The content of Na20 equivalent is equal to 0.89%, and the minimum clinker sulfate, calculated from this Na20 content, is found to be 1.35%.

The clinker is ground, without any addition, in a ball mill at 115 ° C to produce a cement whose specific surface is found equal to 331 m2 / kg.

The agglomeration test gives a value of 48 mm.

With regard to the duration of the setting times, it is noted that the cement has an initial setting time of 50 min and a final setting time of 65 min.

Example 3:

The raw materials, specified in Example 1, are mixed in proportions corresponding approximately to 97.3% of A, 0.2% of B and 2% of C, plus 0.5% of calcium fluoride, then grinds the mixture so as to obtain a powder of raw composition leaving a residue of 9.4% on a 90 mesh screen. From this raw powder, briquettes are molded which are dried and then baked at 1450 ° C to produce a clinker. This clinker is found to have a free lime content of 3.0%; its analysis gives the following results, expressed in oxides (%):

Si02

20.6

ai2o3

5.8

Fe203

2.3

CaO

66.9

S03

1.2

k2o

0.9

Na20

<0.1

F

0.25

The LSF is 1.00, the S / R is 2.54 and the A / F is 2.52. The C3A content is calculated to be 11.4%. The content of Na20 equivalent is equal to 0.69%, and from this value is calculated a minimum sulfate content of the clinker found equal to 1.09%.

The clinker is ground, without any addition, in a ball mill at 115 ° C to produce a cement whose specific surface is found equal to 337 m2 / kg.

An agglomeration test carried out on this cement gives a value of 52 mm.

It is found that this cement has a duration of the initial setting time of 50 min and a duration of the final setting time of 60 min.

Example 4:

The raw materials used are a mixture A of limestone / shale, fly ash B and gypsum C, the analyzes of which are given below:

AT (%)

B (%)

VS(%)

Si02

12.3

44.0

0.7

A1203

3.0

29.4

0.19

Fe203

2.5

9.2

0.15

CaO

43.2

2.6

32.4

S total (calculated in S03)

1.2

0

46.4

Loss on calcination

35.4

9.45

20.2

k2o

0.70

2.2

0.02

NazO

0.31

0.4

0.02

Calcium fluoride (CaF2) is also used, a reactive quality for general use.

The raw materials are mixed in the following approximate proportions: 93.5% of (A), 2.0% of (B) and 4.0% of (C), together with 0.5% of CaF2, then grinds the mixture to obtain a powder leaving a residue of 10.2% on a 90 mesh screen.

Water is incorporated into this raw powder and briquettes are molded which are then carefully dried and then baked at 1400 ° C to produce a clinker whose free lime content is found to be 2.0% and whose analysis reveals a composition, calculated as oxides, specified below (%):

Si02

19.2

A1203

5.0

Fe203

3.8

CaO

65.0

so3

2.9

k2o

0.70

Na20

0.40

F

0.31

The LSF is 1.01, the S / R is 2.18 and the A / F is 1.32. A C3A content equal to 6.8% is calculated. The content of Na20 equivalent is equal to 0.86%, and the minimum clinker sulfate, calculated from this content of Na20, is found equal to 1.31%.

The clinker is ground, without any addition, in a ball mill at 120 ° C to produce a cement whose specific surface is found equal to 333 m2 / kg.

An agglomeration test carried out on this cement gives a value of 49 mm.

With regard to the duration of the setting times, it can be seen that the cement has an initial setting time of 180 min and a final setting time of 230 min.

Example 5:

The raw materials specified in Example 4 (with the exception of gypsum) are mixed in the proportions of 97.5% A, 2.0% B and 0.5% CaF2, then the mixture is ground to obtain a powder leaving a residue of 10.4% on a 90 mesh screen. Water is incorporated into this raw powder, then mold briquettes which, after complete drying, are cooked at 1400 ° C to produce a clinker with a free lime content found equal to 3.2% and of which l analysis gives the following composition, expressed in oxides (%):

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Si02

19.9

ai2o3

5.2

Fe203

4.0

CaO

66.1

so3

1.4

k2o

0.7

Na20

0.4

F

0.26

The LSF is 1.01, the S / R is 2.16 and the A / F is 1.30. A C3A content equal to 7.0% is calculated. The content of NazO equivalent is equal to 0.86%, and the minimum clinker sulfate, calculated from this content of NazO, is found equal to 1.31%.

This clinker is ground, without any addition, in a ball mill at 120 ° C to produce a cement having a specific surface area equal to 337 m2 / kg.

An agglomeration test carried out on this cement gives a value of 45 mm.

With regard to the duration of the setting times, it is found that this cement has an initial setting time of 60 min and a final setting time of 90 min.

Example 6:

The raw materials used are a mixture A of chalk / clay, gypsum B and fly ash C, the analyzes of which give the following results, expressed in percentages:

AT

B

VS

Si02

12.7

0.7

44.0

Ai2o3

4.3

0.19

29.4

Fe203

1.7

0.15

9.2

CaO

43.1

32.4

2.6

S total (calculated in S03)

0.75

46.4

0

Loss on calcination

35.4

20.2

9.45

k2o

0.80

0.02

2.2

Na20

0.22

0.02

0.4

Reactive grade calcium fluoride is also used for general use.

These raw materials are mixed in the approximate proportions of 92.65% of A, 6.0% of B, 1.0% of C and 0.35% of CaF2, then the mixture is ground to obtain a raw powder leaving a 7% residue on a 90 | x mesh screen.

Water is incorporated into this raw powder, then briquettes are molded which are then carefully dried, then baked at 1400 ° C to produce a clinker whose free lime content is found to be 0.9% and whose l analysis reveals a composition, calculated as oxides, specified below (%):

Si02

18.5

AI203

6.3

Fe203

2.5

CaO

64.6

so3

3.5

k2o

1.0

Na20

0.26

F

0.23

The LSF is 1.02, the S / R is 2.10 and the A / F is 2.52. A C3A content equal to 12.4% is calculated. The content of NazO equivalent is equal to 0.92%, and the minimum clinker sulfate, calculated from this content of Na 2 O, is found equal to 1.39%.

This clinker is ground, without any addition, in a ball mill at 120 ° C to produce a cement whose specific surface is equal to 326 m2 / kg.

An agglomeration test carried out on this cement gives a value of 48 mm.

With regard to the duration of the setting times, it is noted that the cement has an initial setting time of 200 min and a final setting time of 230 min.

Example 7:

The raw materials specified in Example 6 are mixed in proportions corresponding approximately to 94.65% of A, 4.0% of B, 1.0% of C and 0.35% of CaF2, then the mixture is ground to obtain a raw powder leaving a residue of 7.2% on a 90 mesh screen. With this powder, briquettes are molded which, after complete drying, are baked at 1400 ° C to produce a clinker having a free lime content equal to 0.8% and whose calculated oxide composition is as follows (%) :

Si02

19.0

ai2o3

6.5

Fe203

2.6

CaO

65.5

so3

2.5

k2o

0.95

NazO

0.24

F

0.20

The LSF is 1.02, the S / R is 2.09 and the A / F is 2.50. A C3A content equal to 12.8% is calculated. The content of Na20 equivalent is equal to 0.87%, and the minimum clinker sulfate, calculated from this content of NazO, is found equal to 1.32%.

This clinker is ground, without any addition, in a ball mill at 120 ° C to produce a cement with a developed surface equal to 330 m2 / kg.

An agglomeration test carried out on this cement gives a value of 48 mm.

With regard to the duration of the setting times, it is noted that this cement has an initial setting time of 195 min and a final setting time of 225 min.

Example 8:

The raw materials used are chalk A, kaolin B, sand C, iron oxide D, calcium fluoride E, gypsum F and potassium sulfate G, the analyzes of which give the following results, expressed in percentages:

at

B

VS

D

E

F

G

Si02

2.0

49.9

98.8

1.13

0.1

ai2o3

0.3

34.1

0.2

0.62

-

0.09

- ■

Fe203

0.09

0.8

0.1

96.86

-

0.05

-

CaO

54.4

0.2

0.6

0.53

71.8

32.4

-

Calci loss

nation

42.9

10.5

0.5

0.75

-

20.2

-

so3

0.06

0.01

0.04

0.02

-

46.4

45.94

k2o

0.04

3.4

0.03

0.02

-

0, u2

54.06

F

- •

-

-

-

48.7

-

-

These raw materials are mixed in the following approximate proportions (%):

AT

75.45

B

2.74

VS

11.65

D

1.13

E

0.33

F

6.35

G

2.35

This mixture of raw materials is ground into a raw powder leaving a residue of 4.8% on a 90 mesh screen *. As in the previous examples, water is incorporated into this powder and mold briquettes which are then completely dried,

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then cooked. In the present example, the cooking temperature is 1400 ° C. The clinker thus produced has a free lime content of 2.40%, and it has the following composition, indicated in oxides (%):

Si02

22.3

ai2o3

1.8

Fe203

1.9

CaO

69.0

so3

2.9

k2o

1.2

F

0.14

The LSF is 1.02, the S / R is 6.0 and the A / F is 0.95. A C3A content equal to 1.6% is calculated. The content of Na 2 O equivalent is 0.79%, and the minimum clinker sulfate, calculated from this Na 2 O content, is found to be 1.22%.

This clinker is ground, without any addition, in a ball mill at 115 ° C to produce a cement having a specific surface area equal to 444 m2 / kg.

An agglomeration test carried out on this cement gives a value of 49 mm.

It is found that this cement has a duration of the initial setting time of 145 min and a duration of the final setting time of 195 min.

Example 9:

The raw materials described in Example 8 are mixed in the following approximate proportions (%):

AT

75.43

B

4.82

VS

10.48

D

0.36

E

0.33

F

6.36

G

2.22

This mixture of raw materials is ground into a raw powder leaving a 5.9% residue on a 90 µ mesh screen. This raw mixture is pressed into briquettes which are then carefully dried and then cooked at 1400 ° C to give a clinker whose free lime content is found to be 1.62% and which precedes the following composition, calculated as oxides (%) :

Si02

22.6

ai2o3

2.8

Fe203

0.8

CaO

68.8

so3

2.7

k2o

1.3

F

0.16

The LSF is 1.00, the S / R is 6.3 and the A / F is 3.5. A C3A content equal to 6.07% is calculated. The content of Na20 equivalent is found to be 0.86%, and from this content a minimum clinker sulfate equal to 1.30% is calculated.

This clinker is ground, without any addition, in a ball mill at 115 ° C to produce a cement whose specific surface is found equal to 448 m2 / kg. An agglomeration test carried out on this cement gives a value of 58 mm.

It is found that this cement has a duration of the initial setting time of 140 min and a duration of the final setting time of 170 min.

Example 10:

The raw materials described in Example 8 are mixed in the following approximate proportions (%):

A 73.94

B 9.60

C 7.00

D 0.75

E 0.33

F 6.38

G 1.97

This mixture of raw materials is ground into a raw powder leaving a 5.2% residue on a 90% mesh screen. With this powder, briquettes are molded which are then completely dried, then baked at 1400 ° C to give a clinker whose free lime content is found to be 1.8%, and whose analysis makes it possible to calculate the following composition (%):

Si02

20.4

ai2o3

5.2

Fe203

1.4

CaO

67.3

so3

2.8

k2o

1.3

F

0.17

There is an LSF of 1.02, an S / R of 3.1 and an A / F of 3.71. The calculated C3A content is 11.4%. The Na20 equivalent is 0.86%, making it possible to calculate a minimum clinker sulfate equal to 1.30%.

This clinker is ground, without any addition, in a ball mill at 115 ° C, and a cement is thus obtained having a specific surface area equal to 457 m2 / kg. This cement, subjected to the agglomeration test, gives a value of 45 mm.

It is found that this cement has a duration of the initial setting time of 120 min, and a duration of the final setting time of 185 min.

Example 11:

The raw materials used are a chalk / clay mixture A, sand B, ground commercial chalk C, gypsum D, potassium sulphate of reactive quality for general use E and calcium fluoride of reactive quality for l general use F, the analyzes of which give the following results (in percentages):

at

B

VS

D

E

F

Si02

12.7

97.8

2.1

0.1

ai2o3

3.3

1.3

0.2

0.09

-

-

Fe203

1.6

0.1

0.07

0.05

-

-

CaO

44.9

-

54.6

32.4

-

71.8

Loss on calcination

35.6

0.3

42.8

20.2

-

-

so3

0.29

-

0.07

46.4

45.94

-

k2o

0.73

0.72

0.02

0.02

54.06

-

Na20

0.16

0.11

0.02

-

-

-

F

48.7

These materials are mixed in the following approximate proportions (%):

At 15.05

B '13.66

C 62.21

D 6.55

E 2.00

F 0.50

This mixture of raw materials is ground so as to obtain a raw powder leaving a residue of 5.8% on a 90 mesh screen. Briquettes are molded from this powder, which are then completely dried and then baked at 1400 ° C, which gives a clinker with a free lime content of 0.8%, the analysis of which reveals the following composition, calculated as oxides (%):

Si02 26.9

A1203 1.5

Fe203 0.57

CaO 67.8

5

10

1S

20

25

30

35

40

45

50

55

60

65

646123

S03 0.91

K20 0.42

Na20 0.10

F 0.14

The LSF is 0.87, the S / R is 13.0 and the A / F is 2.63. A C3A content equal to 3.0% is calculated. The content of Na20 equivalent is 0.38%, making it possible to calculate a minimum clinker sulfate equal to 0.69%.

This clinker is ground, without any addition, in a ball mill at 115 ° C, which gives a cement having a specific surface equal to 450 m2 / kg.

An agglomeration test carried out on this cement gives a value of 45 mm.

It is found that this cement has a duration of the initial setting time of 215 min and a duration of the final setting time of 260 min.

Example 12:

The raw materials described in Example 11 are mixed in the following approximate proportions (%):

A 45.79

B 7.10

C 38.07

D 6.55

E 2.00

F 0.50

This mixture of raw materials is ground into a raw powder leaving a residue of 6.9% on a 90 µm mesh screen. This raw mixture is pressed into briquettes which are then completely dried, then cooked at 1350 ° C to give a clinker having a free lime content equal to 1.5%, and the analysis of which reveals the following composition, calculated as oxides ( %):

Si02

22.2

A1203

2.7

Fe203

1.2

CaO

67.2

S03

3.6

k2o

1.5

Na20

0.11

F

0.25

The LSF is 0.98, the S / R is 5.7 and the A / F is 2.25. A C3A content equal to 5.1% is calculated. The Na20 equivalent is 1.10%, making it possible to calculate a minimum clinker sulfate equal to 1.62%.

This clinker is ground, without any addition, in a ball mill at 115 ° C, which gives a cement having a specific surface equal to 453 m2 / kg.

An agglomeration test carried out on this cement gives a value of 54 mm.

It is found that this cement has a duration of the initial setting time of 215 min and a duration of the final setting time of 270 min.

Example 13:

The chalk / clay mixture A, the sand B and the calcium fluoride F described in Example 11 are mixed together in the following approximate proportions (%):

A 97.1

The resulting mixture is ground to obtain a raw powder leaving a 7.3% residue on a 90 µm mesh screen. Briquettes are molded from this raw powder, which, after drying, are cooked at 1375 ° C to a free lime content of 1.3%. A clinker is thus obtained, the analysis of which reveals that it has the following composition, calculated as oxides (%):

Si02

22.2

ai2o3

5.0

Fe203

2.4

CaO

66.9

so3

0.1

k2o

0.65

NazO

0.13

F

0.49

The LSF is 0.96, the S / R is 3.0 and the A / F is 2.08. A C3A content equal to 9.2% is calculated. The content of Na20 equivalent is 0.56%.

This is an example of a clinker in which the setting regulator component incorporated is fluorine alone. Consequently, the concept of minimal clinker sulfate does not apply to it.

This clinker is ground in a ball mill at 120 ° C, without any addition, and a cement is thus obtained whose determination of the specific surface gives a value of 345 m2 / kg.

An agglomeration test carried out on this cement gives a value of 49 mm.

It is found that this cement has a duration of the initial setting time of 105 min and a duration of the final setting time of 280 min.

30

35

Claims (19)

646,123 2 1. Portland cement clinker, characterized in that it comprises, as incorporated setting regulating component: a) sulphate, in the presence of an alkali metal in a combined state, and / or b) halogen, in a combined state, said setting regulating component being present in a sufficient proportion to prevent premature setting of the cement produced from said clinker. 2. Clinker according to claim 1, characterized in that it contains halogen in a proportion by weight of between 0.01 and 1% of the weight of the clinker. 3. Clinker according to claim 2, characterized in that it contains halogen in a proportion by weight of between 0.1 and 1% by weight of the clinker. 4. Clinker according to one of the preceding claims, characterized in that it comprises fluorine as halogen. 5. Clinker according to one of the preceding claims, characterized in that it comprises alkali metal in a proportion by weight expressed in NazO equivalent of between 0.1 and 3% of the weight of the clinker. 6. Clinker according to claim 5, characterized in that it contains alkali metal in a proportion by weight expressed in NazO equivalent of between 0.4 and 2.0% by weight of the clinker. 7. Clinker according to one of the preceding claims, characterized in that the alkali metal is potassium or a mixture of potassium and sodium. 8. Clinker according to one of the preceding claims, characterized in that it contains sulphate in a proportion by weight of between 0.33 and 5% of the weight of the clinker. 9. Clinker according to claim 8, characterized in that it contains sulphate in a proportion by weight of between 2.0 and 4.0% by weight of the clinker. 10. Clinker according to claim 9, characterized in that it contains fluorine in a proportion by weight of between 0.15 and 0.30% of the weight of the clinker, and in that it contains alkali metal in a proportion by weight expressed in Na20 equivalent of between 0.60 and 1.0% of the weight of the clinker. 11. Clinker according to one of the preceding claims, characterized in that it contains calcium langbeinite. 12. Clinker according to one of the preceding claims, characterized in that it has a silica ratio not exceeding 2.80. 13. Clinker according to one of the preceding claims, characterized in that it has a content of tricalcium aluminate greater than 5%. 14. Method for the manufacture of a Portland cement clinker according to claim 1 consisting in heating until partial melting a mixture of materials mainly containing lime and silica together with a smaller proportion of alumina and iron oxide, process characterized in that the heating is carried out in the presence of: a) a material containing sulfur and a material containing alkali metal, and / or in the presence of b) a material containing halogen, under conditions such that sufficient sulphate and alkali metal and / or sufficient halogen is retained within the clinker to act as an incorporated setting regulating component which prevents premature setting of a produced cement from said clinker. 15. The method of claim 14, characterized in that the sulfur-containing material comprises calcium sulfate, a calcium sulfate hydrate, an alkali metal sulfate, a double sulfate of alkali metal and calcium or a mixture of at least two such substances. 16. Method according to one of claims 14 or 15, characterized in that calcium fluoride is used as the halogen-containing material. 17. Method according to one of claims 14,15 or 16 for the manufacture of a clinker according to one of claims 2 to 13. 18. Use, by grinding, of the Portland cement clinker according to claim 1 for the production of Portland cement. 19. Use, by grinding, of the Portland cement clinker according to claim 18, characterized in that the grinding is carried out practically in the absence of added sulfate.