DD201137A1 - METHOD FOR PRODUCING BELITIOUS CEMENT - Google Patents

Abstract

The invention relates to a process for the production of high-litter cement with the addition of sulphatic rock substances. The object of the invention is to produce a cement rich in cement, whose strength-time function is similar to a Portland cement, the cooling expenses are reduced. The object of the invention is to achieve an effective cooling of the Belit clinker and to improve the grindability. According to the invention this is achieved in that at a mean Kuehlgradient the clinker between firing temperature and 800 grd C <250 K / min, in the cooling zone of the clinker sulphate rock with a particle diameter <10 mm and in an amount up to 20% zugefuehrt. The advantages of the invention are that the Abkuehlgradient can be reduced without this loss of strength occur and the grindability is improved.

Description

232 45 9 2

Process for producing cement cements

Field of application of the invention

The invention relates to a process for producing cements rich in litter with gypsum rock. It is suitable for the production of belitzement and other useful binders.

Characteristic of the known technical solutions

The production of cements rich in lignocites, whose main mineral is the dicalcium silicate (C ₂ S), is known. Thus reports KÜHL (H. Kühlt Cement-Chemie, Bd * II, Verlag TECHNIK Berlin, 1958, 3 · revised edition p. 659 and p. 663) concerning the development of a cement with low heat cement from the 1930s in Sweden and the USA. The disadvantage of this cement is the slow hydration and solidification associated with the dicalcium silicate, which increased to higher strengths only at a later hardening age · The Portland cements show a faster strength development · However, this results in a faster release of the heat of hydration · Furthermore, the universal use of Portland cement clinker

-7.AÜG.1981 * Ö5219

232459 2

Cements achieved with the above-mentioned cementation cements only by a greater specific heat expenditure for the Portland cement clinker · From the Portland cement production is further known to grind the Portland cement clinker with gypsum and / or anhydrite · The amount of added to the clinker gypsum and / or anhydrite is limited by the limits specified in TGL 28 101/01 for the total sulfur trioxide in the cement · Depending on the type of cement, these limits are between 3.5 % and 4.5 % · In addition, the grinding of Portland cement clinker with anhydrite and additives such as Angitporphyrit, slags and lignite filter bags usual · also known from DE-OS 26 32 691 to produce a cement from two clinker, with a clinker Portland cement clinker and the other is fired using the cooling heat of Portland cement clinker · This gebran with the cooling heat of Portland cement clinker The clinker is a porous marl clinker that contains calcareous hydrated mineral phases, including considerable amounts of bark.

The aim of this invention is primarily to heat the second component so far that a conversion process takes place in order to make this component also capable of hydration.

More recently, it is also known to increase the early strength of heat economically favorable, creeping cements without proportionate Portlandzementklinker · Xn the WP 139 938 a firing regime between 1300 ⁰ C to 1450 ⁰ G of cement raw meal with a lime standard is limited by 75 with subsequent intensive milling of clinker, In order to obtain so-called active bark · .Dachteilig here are expenses for intensive grinding "In WP 138 197 is the burning of a Belit raw meal with a lime standard 75-85 at firing temperatures in the range between 1350 ⁰ C and 1450 ⁰ C and subsequent quenching Belitklinkers with cooling gradients greater than 500 K / min described · In this patent, in particular

232459 2

In particular, the high cooling gradient for the temperature range of the cooling between 800 ⁰ C to 1300 ⁰ C highlighted. Air and / or water are referred to as cooling medium. The resulting water vapor advantageously shortens the firing process. The process of reducing the cooling gradient and, associated therewith, the reduction of the air and / or water requirement, remain capable of improvement.

In WP 142 704, the firing temperature is limited to preferably 1300 ⁰ C and the clinker grain size to 90 % less than 7 mm called to guarantee the quenching effect of clinker grains with air · The reduction of Klinkerkb'rner can in a known manner by increasing the Silicate modules are supported ·

It has already been suggested that the oversize of the clinker, preferably greater than 7 mm, is separated from the clinker stream, cooled and ground in whole or in part with other clinker. The expenses for the high cooling gradient and for the separation of the oversize are also disadvantageous here.

In addition, quenching with cooling gradients of less than 500 K / min is carried out at the expense of an increasing silicate module, although the grinding costs for raw meal production increase when sand or quartz-containing clays are to be used as silicic acid carriers Down shaft coolers described, can be realized with the cooling gradient of> 500 K / min · The construction costs as well as the operating costs for the rapid cooling can be improved and must be reduced ·

It has also been proposed to increase the early strength of rapidly cooled active Belitzement Clinker by a proportion of non-sulphate-bound alkalis in the clinker of 0.2 to 3 % . The raw meal is to be adjusted within the limits of the stated limits taking into account the introduction of alkali by the fuel.

- ⁴ - 232459 2

Object of the invention

The aim of the invention is to produce a cementitious cement, whose strength-time function is similar to cements of the Fortlandzement type and at the same time the cooling costs are reduced ·

The object of the invention is to achieve effective cooling for the Belit clinker and at the same time to improve the grindability of the clinker. The method according to the invention achieves this by adding sulfate-containing rocks to the cement clinker in the region of the cooling · The rock is crushed and, with a grain size of less than 10 mm, is preferably introduced into the transition zone between the furnace and the cooler and mixed with the clinker »The heat is transferred to the stone grain through the direct heat transfer between the solids and through the heat-transporting cooling air. · The rock grain decreases The heat on · It leads to complete drainage of the gypsum rock · The resulting water vapor atmosphere has a favorable effect on the firing process · The amount of the registered gypsum and / or anhydrite rock is 20 % based on anhydrous, sulfate-containing rock and the clinker senstrom limited, wherein the amount of sulfate rock is preferably 6 % to 12 % . The mass flow of clinker and sulphate rock mixed in the cooler passes via transport devices and, if necessary, interim storage to the cement mill and is ground into it i.doRe without further addition of sulphate stone. In the procedural embodiment it is also possible to use a mixture of sulphate, carbonate and / or silicate aggregates use · The content of sulfur trioxide in the mixture is at least 10 % based on the anhydrous mixture ·

- 232459

Daa process of the invention will be explained with reference to an embodiment "In a laboratory apparatus, a belitreicher cement clinker was fired with a lime standard of 81 at 1350 ⁰ C and cooled by an average cooling gradients between 1350 ⁰ O 800 ⁰ O of 1000 K / min by air · In a third experiment, the clinker was cooled with a much lower cooling gradient. In a third experiment, a predetermined amount of gypsum rock was added to the clinker at the same cooling gradient as in the second experiment. The meals for the same cement surface behave like the 1x1: 0.9 × the 3-day compressive strength was determined as a ratio of the strengths of 1 s 0.85 t 1.19 and for the 28-day compressive strength of 1 ι 0.9 s 1.02 ×

The advantages of the method according to the invention can be seen from the ratios given in the example. The proportionate addition of gypsum and / or anhydrite reduces cement costs by reducing the amount of milled clinker in cement. Grindability is improved, thereby reducing the cost of cement grinding. "The addition of sulphate-containing rock allows the cooling gradient to be further reduced. on the other hand, the early strength can be advantageously increased with the method according to the invention.

Claims (2)

-β- 232459 2 Invention claim 1 · A process for the production of high-cement cement with the addition of sulfate-slate rock materials, characterized in that at an average cooling gradient of the clinker between firing temperature and 800 ⁰ C <25O / min, in the cooling zone of the clinker, preferably in the transition region between the sintering zone and cooling zone, sulphate Rock substances with a particle diameter of preferably <10 mm and in an amount of up to 20 %, preferably 5-15 % _9, based on the Klinkermassenstrpm registered and mixed with the clinker · 2) Process according to item 1, characterized in that a substance mixture of sulfate-containing, carbonate-containing and / or siliceous rock substances up to 30 % based on the clinker mass flow is introduced and the content of sulfur trioxide in the mixture is at least 10 % .