DD230708A3 - PROCESS FOR THE PREPARATION OF RAW MATERIALS FOR BUILDING MATERIAL MIXTURES - Google Patents

Abstract

In the production of aerated concrete, a method is characterized in that initially all dry components are ground together or successively to form a homogeneous dry mixture. The upstream drying of the mostly earth or pit-wet sand is particularly energy-consuming and requires large separate drying plants. The invention shows a method in which earth-moist sand in the grinding process undergoes drying by mixing components of the aerated concrete dry substance belonging recipe to the starting material for gas concrete mixture, absorb by the inventive method shown, however, without quantitative increase and without loss of effect the moisture of the sand.

Description

-2- 590

embodiment

The invention will be explained below using an exemplary embodiment.

As an example, the preparation of a gas concrete mixture with earth-moist sand as a silicon carrier, gypsum hemihydrate as.

Sulfate carrier and cement and lime are shown as a binder in a dry treatment process.

For this purpose, less than 5% by weight of dewatered dry earth sand as silicon carrier, 25-30% by weight of cement as binder and 3-7% of gypsum hemihydrate as sulfate carrier are ground dry in a mill.

Both the cement and the plaster of paris first absorb the moisture of the sand.

The cement forms a hydration shell by absorbing the sand moisture on its surface, which reduces the binding power and the reactivity of the cement. However, joint re-grinding of the cement with the sand and the gypsum hemihydrate destroys the hydrate shell of the cement particles, increases the surface area of the cement and thereby restores the original activity of the cement.

When taking up the moisture of the sand by Gipshaibhydrat also takes place a hydration of gypsum hemihydrate. Due to the hydration, the chemical reactivity of the gypsum hemihydrate as sulfate carrier is not impaired and the gas concrete mixture is supplied with the amount of S0 ₃ required for the stiffening process.

The lime quantity according to the recipe is added to the dry millbase and, together with the dry sand, the activated cement and the finely divided gypsum hydrate, ground into a ready-to-use homogenous gas concrete starting material.

Claims (1)

-1- 590 18 Invention claim: A process for the treatment of raw materials for gas concrete mixtures, such as dry sand, cement or cement clinker, quicklime and gypsum hemihydrate, wherein the sand is dewatered to ^ 5 wt .-% moisture, characterized in that the dewatered sand with the cement or cement clinker and the Ground the gypsum hemihydrate until it is dry and then add the Branntkalt. Field of application of the invention The invention relates to a process for the treatment of raw materials for aerated concrete mixtures using earth-moist sands as silicon carrier. Characteristic of the known technical solutions In the treatment of raw materials as a starting material for the production of aerated concrete, there are essentially two known processes, wet and dry milling. When wet grinding, the grinding of the sand takes place as a silicon carrier in humid humid 'state with the addition of water and optionally a sulfate carrier, preferably anhydrite, to a binder-free sand sludge, then only in the mixer, the remaining building material components such as cement, lime in the various forms and other admixtures are added. This process has the advantage of abundant storage with a calcium sulfate-enriched sand sludge as a starting material for different aerated concrete formulations, but with the disadvantage that the admixture of the specific aerated concrete components in the mixer does not guarantee homogeneity of the mixture. This homogeneity of the mixture is achieved by a dry processing in which all gas concrete components are ground together in a mill to a dry raw material mixture and in the mixer only the water is added with the formulation-related additives. This method has the disadvantage that all components must be introduced completely dry into the mill and thus the earth-moist silicon component sand requires only an energy-consuming and time-consuming drying. For this reason, DE-OS 1771635 has disclosed a method for using earth-moist silicon carriers in the dry grinding method, in which part of the quicklime intended for the mixture is added to the soil-moist silicon carrier in a mill. During grinding, the hydration of the lime deprives the silicon carrier of its adhering moisture. The heat generated during hydration also contributes to the drying of the silicon carrier. Thus, the grinding process to a dry grinding process, in which all the necessary for the preparation of the required gas concrete raw material mixture dry components such. .B quicklime, cement and sulphate carriers are first ground to a homogeneous dry mixture without any chemical reactions. This millbase is then mixed in a mixer with the intended amount of water and a propellant to a reactive plastic or pourable gas concrete mixture. This method has the disadvantage that due to the hydration of a part of the quicklime provided as binder during the drying of the earth-moist silicate-containing component, part of its binding force is no longer available during the later blowing and stiffening process, and, moreover, the heat of hydration of the residual hydrated lime remains insufficient to generate the heat of hydration required for the gas concrete blowing process. This requires additional lime additions. Object of the invention It is the object of the invention to exclude the disadvantages and to make the use of humid sands for the preparation of homogeneous mixed gas concrete mixtures for different recipients energy and material economics. Explanation of the essence of the invention To achieve the objective, the task is to develop a method by using dry earth sand as a silicon carrier dry processing of the raw materials for the production of gas concrete mixtures is achieved, the hydration of the lime used only at the time of the blowing and Stiffenprozesses the gas concrete mixture. The other components of the mixture should not be impaired in their function and effect at normal doses. According to the invention, this object is achieved in that S as 5% moisture dehydrated sand as a silicon carrier together with the formulation, provided as a binder, cement quantity in the form of ground cement or cement clinker and with the total amount of provided as sulfate carrier in the gas concrete mixture Gipshalbhyddrates in a mill is filled into a common grinding process and the grinding process is carried out until the earth-moist sand has completely lost its moisture to the cement and the gypsum hemihydrate. Thereafter, the grinding is continued until the sand has reached the desired fineness and the cement, by further grinding, has reached an activity corresponding to its original binding capacity. Only then is the dried lime material added with the recipe-appropriate amount of lime and ground into a homogeneous dry raw material mixture for producing gas concrete.