3. The history of obtaining and production cement

This material is obtained by mixing finely ground clinker and gypsum. Their equity ratio depends on what brand of cement needed. What is the first component? This mixture of fines of limestone and clay, which as the temperature rises to 1 400-1 500 ° C to melt and begin to "seize" with each other. As a result - the formation of clinker granules. In the next stage of production, they are brought to the "flour" state and mixed with gypsum (until smooth).

cement production scheme

Because of the nature of production, it can be divided into the following stages:

• raw material delivery. Given the cost of transport enterprises for the production of cement is economically advantageous to place the vicinity of clay and limestone mining (major components);

• the process of grinding and mixing fractions;

• firing the cement mass;

• grinding to a powder;

• the addition of gypsum and other substances (if provided by the cement manufacturing technology);

The lion's share of all production costs for cement (up to 75-80%) falls to the clinker.

There are a number of manufacturing technologies. Choosing the best option depends on the quality of raw materials and available in the capacities of the enterprise (primarily for heat treatment of materials).

clinker production methods

They differ in the specifics of the preparation and processing of raw materials.

"Dry"

         As the name suggests, that the use of a liquid is not assumed. First, the basic ingredients of the cement are broken into small fractions, triturated, then this is done thorough mixing flour (limestone + clay) with compressed air (with simultaneous drying and adjusting the ratio of share of ingredients). Final stage - calcining the resulting mixture and converting the cement "flour". It can be produced in a rotary kiln, or the mine.

        This method is the most cost-effective and is increasingly being used in new or upgraded facilities.

           "Wet"

      There are several methods of implementing this method of manufacturing cement, which depend on the properties of the components of (primarily of their density). Consider the most commonly used.

Chunks of limestone, coming to the company, rather large. Therefore organized their first crushing (2 - 3 steps) until all fractions are obtained with dimensions not exceeding 10 mm. If necessary, Roller units made further (final) split.

        The same raw material preparation technique for the cement is applied to the clay, which is then soaked in the so-called "mash". Humidity resulting slurry can be 65-70%. He served in the "mill", which simultaneously receives and ground limestone. There is a simultaneous additional grinding and mixing clay clinker components.

         If used in the production of cement or chalk tuff (soft limestone), the technology is somewhat different. Stirring was further performed with clay in the milling step (a crusher), then soaked weight. The final grinding is performed in "mill".

The resulting mass of not more than 40% moisture, with the help of pumps is supplied to the vertical-type swimming pool, where finally adjusted the percentage of cement components. Next - horizontal pool, from which you are downloading in the kiln.

The final step is the cooling of the mass, and its transformation into a "flour". Then - in the silo for storage of the finished cement.

This method makes it possible to achieve high homogeneity of the product, even in cases where the starting materials are very different in their characteristics (e.g., hardness) or impurities present in them. But there is a drawback - the increased consumption of thermal energy.

Basically, in this way it is organized the production of cement in most of our businesses, since they were built during the Soviet period and were "imprisoned" is on this technique.

"Semi-dry"

After grinding to a fraction the size of no more than 20 mm dried clay and limestone. After the end of the process the moisture level in the material is between 10 - 15%. Preliminary heat treatment of the cement components produced in "Lepol furnaces." The pellets are tray on a tray, through which pass the gases, their warming up to 950 ° C. This allows not only the dry mass, but also reduce the level of carbonation approximately ¼. Thereafter enters the furnace clinker (shaft) for firing. Furthermore - in grinding hopper.

"Combined"

Such a process combines the two techniques ("wet" and "semi-dry"). Prepared in a "mill" sludge with humidity at 40-45% passes through a filter, where it is dehydrated (up to 15- 18%). Next - the mixing of raw materials for cement dust from the gases in the furnace "Lepol". This further reduces the level of the liquid content of 3-5%.

Thereafter, the mass is fed into the rotary kiln, fired, and after the final grinding in a "flour" finished cement is sent to the repository.