CS222885B1 - A method of producing a lime-belitic binder with a delayed start of hydration - Google Patents

Abstract

The invention relates to a method for producing a lime-belitic binder with a delayed start of hydration. The essence of the invention lies in the fact that the raw material mixture for the production of a lime-belitic binder is homogenized with 1 to 4% by weight of calcium sulfate before firing, as a result of which a low-viscosity sulfate melt is formed in the binder during firing, which slows down the hydration of the binder component - free lime and thus also the start of hydration of the lime-belitic binder. The invention can be used in the field of production of binders for aerated concrete.

Description

22288S

BACKGROUND OF THE INVENTION The present invention relates to a method for producing lime-belitic binder with a delayed start of hydration.

So far, known processes for the production of lime-binder binder, used, for example, in the USSR or in the CSSR tested on the basis of A.O. 209 574, consisting of grinding of natural raw materials, their dry homogenization, or wetting of the raw material mixture, firing of 1100-1350 ° C and grinding to a specific surface area of 2500-3500 cm 2 / g according to Blaina. The composition of the raw material mixture is adjusted so as to form as minerals: the bleach - betadicalium silicate and the free lime (CaO) and the calcium aluminate and calcium aluminate interferences after the raw material blend has passed. The sinter may contain up to 10 wt. After mixing with water, the individual components hydrate, but preferably the free lime and the solidification process take place. The curing process is more pronounced only under hydro-thermal conditions. When used for example in the production of aerated concrete, the free lime is too hydrated from the binder to solidify the porous mass prior to the formation of a sufficient amount and pore volume, resulting in a cellular concrete bulk density (one of the major ones). quality parameters) higher than the current ČSN standards.

This drawback removes the production of a hydrated lime-belitic binder, which has the advantage of producing a small proportion of homogeneously dispersed low viscosity sulphate in the binder, reducing the hydration activity of free lime.

BACKGROUND OF THE INVENTION The present invention relates to a process for the production of hydrated lime-bell binder, which differs from the known lime-binder production methods, and is combined with the basic raw materials (limestone and clay) to homogenize calcium sulfate in a quantity of 1. - 4 wt.

SUMMARY OF THE INVENTION The present invention provides a process for producing a hydrophilic binder with a delayed start of hydration such that 80 to 90 wt. of limestone containing MgO to 6.5 wt. is ground and homogenized with 10 to 20% by weight. cement clay and with one to 4 wt. calcium sulphate of any mineral form and origin, but at least 30% SO 3, the mixture is stirred at 1100 to 1350 ° C, preferably 1200 ° C for 1 to 4 hours, and after cooling, the clinker is ground to a specific surface area of 2500 to 3500 cm 2 / g according to Blaina. The advantage of producing the lime-belitic bond according to the present invention is the controllable hydration time of the free lime and binder component which is directly proportional to the SO3 content of the binder. A further advantage is the possibility of using calcium sulphates formed as waste from various chemical products (e.g., so-called phosphosadium) - preferably wet-grinding and homogenizing the feedstock mixture. On the other hand, natural gypsum and anhydrite (or mixtures thereof) used by each cement plant as cement hardeners are better applied when dry-grinding and homogenizing the raw material mixture. The following examples are intended to illustrate the process for producing the hydrated lime-belitic bonding agent of the present invention without limiting the scope of the invention in any way. 5 kg of limestone containing 6 wt. MgO was dry milled and homogenized with 1 kg of cement clay and with 240 g of natural gypsum (containing 35.41% SO3), the mixture was fired at 1200 ° C and after rapid cooling it was milled to a specific surface of 3100 cm 2 / g according to Blaina. Low-quality lime-belitic binder low-quality parameters, satisfactory for aerated concrete production: CO2 content: 1.95% content. vol '. CO2: 41.35% moisturizing activity (according to ČSN 722 230 —change and — 10/1977):

2nd minute: 23 ° C 6. minute: 31 ° final: 50.5 ° C in 19 minutes. Example 2 5 kg of limestone containing 6% w / w. The MgSO4 was wet milled and homogenized with 1 kg of cement clay and with 180 g of phosphorous gypsum with a humidity of 33% (and containing 44.09% SO3 in dry matter), the mixture was fired at 1200 ° C and after rapid cooling. was measured to a specific surface area of 3000 cm 2 / g according to Blaina. The so-obtained lime-belite binder has little subsequent quality characteristics, suitable for the production of porous concrete:

CO2 content: 2,01% vol. Content CaO: 40,50% hydration activity (according to ČSN 722 230 —change and —10 / 1977):

2. minute: 24 ° C 6. minute: 35 ° final: 52 ° C in 14 minutes. The hydrated delayed lime-belitic binder of the present invention has been used in the manufacture of building elements by autoclaving, preferably in the manufacture of porous concrete.

Claims (1)

222885 A method for producing a lime-belitic bond with a slow start of hydration, characterized in that 80 to 90% by weight of the lime with a MgO content of up to 6.5% by weight. % carbon black and homogenized with 10 to 20% by weight of cementitious clay and with 1 to 4% by weight of cementitious clay; However, the mixture is burned at 1100 to 1350 ° C, preferably at 1200 ° C for 1 to 4 hours, and after cooling, the mixture is calcined. grinds to a specific surface area of 2500 to 3500 cm 2 / g, according to Blaina.