CZ2007429A3 - Mixture for producing high-alumina cements - Google Patents

Abstract

The mixture for the production of aluminous cement contains an aluminate raw material, limestone, aluminous cement and anodite. Weight ratio Al.sub.2.n.O.sub.3.n. %: CaO is 1.4 to 4.6: 1. and the water content is 2 to 28 wt. In a preferred composition for the production of aluminate cement, one of the constituents is an aluminous cement made from a mixture of the same composition.

Description

Mixture for the production of aluminous cements

Technical field

BACKGROUND OF THE INVENTION The present invention relates to a composition from which abrasion resistant agglomerates for the production of aluminous cements can be prepared.

Background Art

Conventional compositions for the production of aluminous cements generally consist of. aluminous raw materials (eg baiixite, alumina, hydrated alumina) and lime raw materials (usually limestone). The mixtures are calcined in the production of aluminate cements and the calcined calcine is ground.

The composition and properties of the alumina cement depend primarily on the purity of the raw materials and the composition of the mixture (in particular the Al; Oj: CaO ratio), the calcination mode as well as the grain size of the aluminate cement produced. Especially CaO.AUV, A (c) and Corundum (c) are present in the calcination of the aluminate cements mixture.

Compositions for the production of aluminous cements are usually in powder form, but may also be agglomerated prior to calcination. The advantage of agglomerated mixtures for the production of lilac rope cements is their low dustiness during handling and especially the possibility to use ovens for calcination. in which the powder mixtures for the production of aluminous cement cannot be cured for technological reasons. In the case of agglomeration of aluminate cement compositions, it is desirable to achieve the best mechanical properties of the agglomerates, i.e., high abrasion resistance and resistance.

A number of modifications to the aluminate cement composition have been published, focusing, for example, on the use of non-traditional raw materials, to improve the economics of production or to improve the properties of aluminous cements, Czech Patent No. 286,988 discloses a process for producing aluminous cement, wherein the aluminate component is a mixture for alumina cement production. In particular, the invention is directed to the use of alum, which is produced as a by-product in the remediation of technological solutions of metal mining. eg uranium. · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · ·

U.S. Pat. No. 4,071,373 describes / processes the production of aluminous cement wherein the aluminate component of the composition for producing aluminous cement is aluminum after-melting residues.

U.S. Pat. No. 4,204,878 discloses the preparation of a raw material composition for the production of aluminous cement which, in addition to lime and hypmitite components, contains at least one Mg metal chloride. Ca, Ba, Sr, Na and K. The advantage of the addition of said chlorides is the reduction of the calcination temperature of the mixture for the production of aluminous cements and the resulting reduction in production costs,

U.S. Pat. No. 4,116,707 discloses a process for producing aluminous cement from a mixture comprising, in addition to aluminium, strontium or barium carbonate, zirconium oxide, and chloride or chloride from the Ba group of metals. Sr, Na and K. It is a method of producing high-refractory aluminous cement.

A disadvantage of the aluminate cement compositions described in the patents is. that they do not contain a binder that increases the strength and abrasion resistance of the agglomerates produced therefrom.

No publications have been found to describe compositions for the production of aluminous cements, whose aglonierates would have improved mechanical properties due to the presence of binders.

SUMMARY OF THE INVENTION

The aluminate cement mixture is characterized by this. that it contains an aluminate raw material, limestone, a cementitious cement and water, with a weight ratio of AUO: CaO = 1.4 to 4.6: 1. the content of aluminous cement is 2 to 19% by weight. and the water content is 2 to 28 wt. A preferred composition for producing aluminous cements is characterized in that the one-component cementitious cement is made from a mixture of the same composition.

Agglomerates can be prepared from the aluminate cement composition according to the invention, which have a higher strength and abrasion resistance as a result of hydration in the mixture of aluminate cement present than those prepared from mixtures which do not contain the cementitious cement. * * ··· ·· · * Μ * · · «« · · # it it it it it t t t t · · · · · EXAMPLES Example 1:

Compositions for the production of aluminous cements consisting of an aluminous raw material, which in this example is gibbsit, further from limestone, alumina cement and water. they have the composition shown in Table 1. These mixtures (Samples # 2 to 5) have the same weight ratio Λ PO,: CaO and contain different amounts of aluminous cement, while the control mixture (Sample No. 1) does not contain aluminate cement.

Said mixtures were agglomerated by compression into tablet form. Tensile bending strength and abrasion resistance were determined 24 hours after preparation. The abrasion resistance has always been quantified as a percentage of the weight of the dust particles generated by the standardized method of mechanically stressing the agglomerates to the total weight of the agglomerates tested. X tablets prepared from all mixtures were alumina cements prepared by kaleinating and grinding, in which the presence of CaO.APO1, CaO.PAPO1, APO4 (corundum) and 12Ca0.7AP0-, was identified by X-ray diffraction analysis. The weight ratio of APO: CaO was calculated from the composition and weight of the raw materials. The properties of the tablets made from the mixtures in this example are also shown in Table 1.

Table 1: Composition of blends for the production of aluminous cements and the properties of tablets by weight. ratio aluminate content water content tablets strength tablets. % Of CaO cement in the blend in the tensile blend bending [% by weight] [wt.%] [MPa] [wt. | 1 2.5 0 8.5 0.24 98.6 2 2.5 2.3 8.5 0.30 96.3 .7 2.5 4.6 8.5 0.41 92.0 4 2.5 9.2 8.5 0.84 77.4 5 2.5 13.8 8 5 1.47 55.6 6 2.5 18.4 _ 8.5 _ 2.26 25.3 4

* I # * ♦ Μ · Example 2:

Compositions for the production of aluminous cements consisting of the aluminous raw material, which in this example is gibbsit, further from limestone, aluminous cement and water, have the composition shown in Table 2. These mixtures differ mainly in their ΛΜ..Τ: CaO ratio.

The mixtures were agglomerated by compression into tablet form. Tensile strength of the tablets was determined by bending 24 hours after preparation. Aluminate cements were prepared from tablets prepared from all mixtures by calcination and grinding. For aluminous cements with AbO weight ratios; : CaO 1.4 and 1.9 (samples 7 and 8) identified the presence of CaO.AbO; phases by X-ray diffraction phase analysis. CaOTAMb and 12Ca0.7AbOi and also AlAT (corundum) phase for aluminous cements with weight ratios of 2.9 and 4.0 (samples no. 9 and 10). The strength of tablets made from aluminate cement compositions in this example is also shown in Table 2.

Table 2: Composition of mixtures for the production of aluminous cements and the strength of the tablet sample. wt. ratio AbO 2: CaO content of aluminous cement in the mixture [wt. j water content of the mixture [% by weight] tensile strength of tensile strength bending [MPa] 7 1.4 9.13 5.71 1.93 8 1.9 9.44 5.90 1.78 9 2.9 9.43 5.92 2.22 10 4.0 9.43 5.93 1.84 Example 3:

Compositions for the production of aluminous cements consisting of an aluminate raw material which is gibbsit in this example. Furthermore, limestone, aluminous cement and water have the composition shown in Table 3. These mixtures differ mainly in the water content. The control mixture (sample No. 11) was prepared without the addition of water. The water content of the summer control mixture was calculated from the moisture of the raw materials.

The mixtures were agglomerated by compression into tablet form. Tensile bending strength and abrasion resistance were determined 24 hours after preparation. The properties of tablets made from aluminate cement compositions in this example are also shown in Table 3.

Table 3: Composition of the composition for the production of aluminous cements and the properties of the tablets sample by weight. ratio aluminate content water content tablets strength tablets. % Al A: CaO cement in the tensile blend in the blend versus abrasion% wt% [wt%] [MPa] [wt. | 11 2.5 10 0.3 0.22 > 99.9 12 2.5 9.7 3.1 1.32 34.5 14 2.5 9.3 7.6 2.88 20.7 15 2.5 9.1 9.3 2.70 19.8 16 2.5 8.9 10.9 2.52 24.8 Example 4:

The mixture (sample No. 17) for the production of aluminous cements consists of the aluminous raw material, which in this example is gibbsit, further from limestone, aluminous cement and water. The control mixture (sample 18) was prepared without aluminate cement. The composition of both samples listed in Table 4.

The mixtures were agglomerated extrudact into noodles. After 24 hours of preparation, the extrudates were dried and then their abrasion resistance was determined. Abrasion resistance of extrudates is also shown in Table 4. 6 • · • · · * * · · • • • • • • • •

Table 4: Compound / control composition composition and abrasion resistance of extrudates sample wt. ratio of aluminate content water content extrudate resistance. :Α: CaO cement in admixture in an anti-abrasion mixture [% by weight] [% by weight] [% by weight] 17 2.5 7.4 26.7 65.7 18 2.5 _1 0 26.7 96.0 Example 5:

The mixture (sample No. 19) for the production of aluminous cements consists of an aluminous raw material, which in this example is corundum, further of limestone, aluminous cement and water. The control mixture (Sample No. 20) was prepared without. aluminous cement. The composition of both samples is shown in Table 5.

The mixtures were agglomerated by extending into noodles. After 24 hours of preparation, the extrudates were dried and their abrasion resistance determined. Abrasion resistance of extrudates is also shown in Table 5.

Table 5: Composition of blends and agglomerate properties wt. ratio of aluminate content water content extrudate resistance. AW); CaO cement in the mixture in the anti-abrasion mixture |% by weight]% by weight] |% by weight] 19 2.5 7.4 26.6 96.0 20 2.5 0 26.6 97.5 Example 6:

A composition for the production of aluminous cements consisting of an aluminate raw material which is gibbsit in this example. further from limestone, aluminous cement and water. had a weight ratio of A PO; CaO - 4.6: 1. and a content of aluminous cement of 9.4% by weight. The mixture was agglomerated by compression into tablets, calcination and grinding to prepare aluminate.

• »« > The presence of CaO.AUh phases was identified by ditraction phase analysis of the cement. (aO.IhO.i. and Al2O3 (corundum)).

Industrial usability

The invention is industrially applicable to the production of aluminous cements, especially when the production is based on calcination of agglomerates.

Claims (1)

1 I t • I «4 lf · · · ·· *» ·· ** Mixture for making aluminous cement characterized by. that contains aluminate raw material, limestone, aluminous cement and water, wherein the ratio of ΑΕΟΐ: CaO - 1.4 to 4.6: 1, the aluminous cement content is 2 to 19% by weight. and the water content is 2 to 28% by weight. The composition of claim 1, wherein the aluminate cement is one of its constituents made from a blend of the same composition.