Process for producing loam scoria The invention relates to a process for producing marl slag and marl slag cements, or combined compounds for mixed marl cements having a CaO / SiO2 basicity of < 2.0 When cement is produced, calcareous and clayey stones, in particular limestone and calcareous loam, are used as raw materials and burned to produce cement clinker. The lime contained in the raw materials is completely destined for silicic alumina and optionally for iron, forming then the cement minerals customary for Portland cement clinker, such as alite, belite, brown and glass milerite. To ensure the desired clumping for cement clinker at comparatively low temperatures of approximately 1350 ° C, relatively high quality raw materials are required and in particular, the highly calcareous limestone loam. The limestone loam, which usually has a basicity of between 3 and 4 and in addition to the lime also contains Si02, A1203 and iron oxides, however occurs in essence, not only in the form of limestone loam, relatively high quality and widely pure, but rather as a common loam or of low quality in considerably larger quantities. The loam, which is considerably more expansive, is characterized by basicities between 0.8 and 2 and is frequently also found in the form of clay loam. These comparatively low-grade raw materials, still substantially more expansive, in conventional cement production processes, can not be used without expensive purification and liming enrichment procedures and are available in large quantities, as cheap raw materials. Slag cements and, in particular, slag cements in the blast furnace, also have hydraulic properties and it has already been shown that, by optimizing the chemistry of the slag and in particular, by adjusting the basicities and content of aluminate, as well as the apply special activation procedures, metallurgical slags can be improved, up to the margin that these correspond to a development of firmness in the concrete and are at least equivalent to the cement clinker. The present invention helps to show loams of sparse and cheap raw material, which have low basicities suitable for economic use in the production of slag cements or mixed components for combined cements, while at the same time, allow the adaptation of the qualities of desired product of the respective requirements for a high degree. To solve this objective, the process according to the invention essentially consists in that in a first step of the process, the clay loam or a mixture of loam and clay having a baslidity of < 2.0, it is dried, preheated and calcined, and after that, the product obtained in a second step of the process, is melted in a separate melting furnace, at higher temperatures than those applied in the first step of the process and granulates the melt. Calcination is an endothermic reaction, considering that the melt constitutes an exothermic reaction. Due to the fact that clayey marl, that is, relatively low grade marl, has an elevated A120 content or a low quality marl mixture and clay having a basicity of less than 2 is dried, preheated and calcined in a first step of the process; it is initially safeguarded that the large quantities of CO2 released during calcination do not need to be heated to the temperatures that are usually required in the production of cement for bonding. The calcination of the hydrate, sulfur and carbonate compounds is carried out subsequently at relatively low temperatures, so that the large quantities of gas released, occur in accordance with the temperature levels, thus improving the thermal efficiency and therefore the economy of the process. Because of the relatively low purities of the initial substances used, then calcination occurs at lower temperatures, than would be the case with highly pure calcium carbonates. Due to the fact that the product obtained in a second step of the process, subsequently melts in a separate melting furnace at higher temperatures than in the first step of the process, there is the possibility of subsequently correcting the composition of the melt, through of any means and it is feasible, by appropriately granulating the melt, providing the desired part of the glass and ensuring that any unwanted crystallization during cooling is avoided. The drying, preheating and calcination in a first step of the process at corresponding low temperatures also allows the use of substantially coarser grain filler substances, as compared to the known cement clinker agglutination processes, so that the preparation of the raw material and in particular, grinding, will not be required as a rule, but the heavy load stocks will simply have to be finely divided. The process according to the invention also requires a substantially lower heat consumption than the clinker process. Conveniently, the process according to the invention is carried out in such a way that the first step of the process is carried out in a suspension type heat exchanger, a rotary tubular furnace, multiple forge furnace or a furnace of a tub, or in a fluidized bed or cyclone preheating unit. In a particularly convenient manner, a suspension type heat exchanger may be employed, where it is feasible, in particular if a rotary tubular furnace or bowl furnace is used in the first step, to choose an even thicker particle size than the existence of loading, drying, preheating and calcination of a filler material, having particle sizes of, for example, up to 40 mm, are easily feasible. In a particularly convenient way, the second step of the process is carried out in a casting cyclone, rotary tubular furnace or forging type furnace, or in an oxidation reactor for iron casting, by means of which even the formation of fluffy slag, it may be convenient if a fusion oxidation reactor is employed. What is essential in obtaining the desired cement technology properties, after all, is the adjustment of the slag basicity of the target slag, which is conveniently processed in such a way that the target slag is adjusted to a CaO basicity / Si02 between 0.9 and 1.85 when mixing loam and clay. If at the same time an A1203 content of between 6 and 20 / weight is sought, a synthetic slag can be obtained to the high quality blast furnace, such as the A1203 content can be obtained in a particularly simple way, using clay loams. When other qualities of the loam are used for the main component, the chemistry of the desired slag can be adjusted with the help of bauxite, clay, flue ash or other industrial waste substances, such as, for example, residues with oxide. iron, sweeps, crushing powders containing corundum or refractory cuts. What is also essential for obtaining the desired technological properties of cement is, of course, according to the rapid cooling, so as to avoid the formation of crystals. Depending on the basicity of the slag, it is characterized by different viscosities, where the slag becomes highly viscous, in particular in basicities of more than 1.4 and the formation of crystals can no longer be reliably avoided in the granulation processes conventional, such as, for example, during granulation in hot water. In the context of the invention, therefore, it is conveniently proceeded in such a way that the melt in basicities of >; 1.4 is spread inside a granulator and in particular, a steam granulator. The granulation by sprinkling, in which the cooling of the melted drops, in most cases, is affected by exploitation by hydraulic means, in water or water vapor, can be substantially improved even more, in that the hydrocarbon It is exploited by hydraulic means inside the spray granulator. The thermal decomposition of the hydrocarbon removes the heat from the drops sprayed in a gradient of 104 to 105 K / s, while simultaneously forming a mixture of one part of carbon oxide and two parts of high quality hydrogen, which corresponds to A further preferred development of the process according to the invention, can be burned in the first step of the process, because the actual heat demand for the calcination increases at that location. Since, due to the relatively low purity of the raw materials, the calcination occurs at relatively low temperatures, the process according to the invention is conveniently carried out in a manner in which the first step of the process is followed at temperatures up to 950 ° C to 1000 ° C, drying takes place at temperatures ranging from 100 to 210 ° C, the preheating takes place from 210 ° C to 600 ° C and the calcination from 600 ° to 1000 ° C. In the second step of the process, in which the slag melts to solidify it subsequently under the formation of a vitreous consistency, it is conveniently proceeded in such a way that the operation occurs at final temperatures of between 1450 ° C and 1550 ° C. As already mentioned before, the process according to the invention is distinguished by avoiding any preparation of raw material difficult to handle, and in particular, by not requiring any crushing of the raw materials. Conveniently, the process according to the invention is carried out in such a way that the first step of the process is carried out with finely divided loam having an average particle size, ranging from 20 mm to 30 mm. In order to improve the technological properties of the cement, it is necessary to proceed according to the invention, in which the dust from the production of the clinker is added to the loading material. Because a melt is produced within the context of the process according to the invention, it is therefore feasible to introduce into the melt the high alkali content which is within the clinker production step powder, therefore it is it forms a product that is particularly reactive and is characterized by high initial strengths. The clinker raw materials, as they are used in the conventional cement production process, as a rule, are characterized by high alkali contents, and the processing of such alkali-rich raw materials, as a rule, constitutes a disposal problem, which can be solved by means of the process, according to the invention. Also the use of other alkali-containing industrial waste substances, for example, those of pulp and paper pulp production, which also include partially high amounts of A1203, as well as organic matter such as lignin, whose calorific value can be used , it is very convenient. If the melt is going to be subjected to a conventional water granulation process, its basicity can be lowered to less than 1.4, whereby in those cases the A1203 content of the target slag must be increased accordingly to achieve a force progress similar to the clinker of the final product. In the context of the process, according to the invention, the use of filler materials having high dolomite content does not have adverse effects, or it simply has to be considered that the MgO portion of the filler material is adjusted to less than 19% by weight. %/weight. Up to these quantities, magnesium oxide can increase the granulation capacity, due to the reduced viscosity of the slag, which will lead to an increased portion of amorphous or vitreous particles. Subsequently, the process according to the invention will be explained in more detail by means of exemplary embodiments. Example 1 A loam slag is produced from the clay and loam from the fillers. The raw materials have the following directional analysis: The raw materials were supplemented with the clinker kiln dust, by which the initial potency of the marl slag increased significantly. In order to adjust the basicity of the Ca0 / Si02 slag, to less than 1.4, in terms of applying conventional water granulation, the portions of the two components in the mixture were determined in the following manner with a target basicity of 1.1, which was sought: Portion of marl (x) = (C / S) -SiQ2 (clay) - CaO (clay) CaO (marl) - (C / S) • Si02 (marl) Portion of marl = 1.1 • 46 - 0.72 = 6.48 33 - 1.1 • 23 Therefore, one part of clay was mixed with 6.48 parts of marl, which resulted in a mixture of 86.6% / weight marl and 13.4% / weight clay. After this, the raw mixture for the loam scum that was intended, had the following composition:
After drying from 100 ° to 210 ° C, preheating from 210 ° to 600 ° C and calcination from 600 ° to 950 ° C, the product dried and calcined, the product was extracted from a suspension type heat exchanger and introduced into a melting cyclone, the temperature was adjusted between 1450 ° and 1550 ° C, where the melt was granulated in hot water. In order to reduce the nitrogen oxide portion, it is also feasible to carry out a progressive back combustion inside the suspension type heat exchanger, when blowing in the combustion air, therefore the thermal efficiency is improved. The fuel used in the melting cyclone in an alternate process duct, in which the melt was expelled inside a spray granulator, was formed by using hydrocarbons during granulation, cracked gas or synthesis gas (mixture of 1 part of carbon oxide and 2 parts of hydrogen) that was formed, had been used as a fuel together with air in the melting cyclone. In addition, this granulation method caused the iron oxide in the slag to be almost completely metallized and separated by subsequent magnetic separation of the slag. Example 2 By using a rotary tubular calcination furnace in the first process step and a forge type furnace in the second step, finely divided loam with a particle size of about 25 mm was used. The marl slag had the following composition:
Due to the relatively high basicity of 1.43, the slag disintegrated when sprayed into a spray granulator, whereby a high portion of fine granules was obtained. Because of the basicity, the high portion of the fine granulates was characterized by a particularly high hydraulic activity. A slag that has a basicity of 1.43, can not be granulated more satisfactorily with hot water, since the portion of disintegrated, which is important from a technological point of view of cement, was inactivated hydraulically because of the formation belite crystal .