28. Development of the pile by rotary excavator

All excavators available on the ad market are divided into single-and multi-bucket model. The first are mainly used on construction sites. They are machines of one cycle, that is, perform some work per unit time.

The latter are used in the mining industry, mining, development of sand pits. They belong to the continuous technique, respectively, have a higher performance than single bucket models. Earthmoving equipment is divided into a continuous rotary machine and the chain of action. Consider wheel excavator.

          

FEATURES

Rotary machines are distinguished device chassis. In particular, the models are made on tracks or rail step-go. High performance technology, is not the only advantage of rotating machinery. Continuous duty cycle operation makes machinery more profitable in financial terms. It is worth noting, best emptying buckets and a minimum number of developed soil losses.

In the models considered, the buckets are located on a large wheel (rotor). It ensures the development of the soil in the optimal direction. If the surface layer is produced, the rotor rotates in clockwise direction. In operation, with the lower layer, the rotation is in the opposite direction. Additionally, ladles are rotated to a vertical or horizontal plane.

Soil sampling in the buckets is conducted as usual, however, emptying the tanks is performed on the following principles: inertia or gravity. In the first case, on the rock in the bucket has the effect of centrifugal force, ejected in the soil from the tank. When a gravitational method, discharge is due to produce its own weight.

TECHNICAL SPECIFICATIONS

The rotor is located on the telescopic boom or stationary. Changing boom position in space is due to the winch, the cable which passed through tackles mast. Adjusting the position of the boom, it is done by the established balances.

It is worth noting that this type of excavator has two kinds of arrows: dumping and rotor. the same scheme lifting and lowering is provided for each design. Together, this forms a superstructure of the excavator, which is rotated by 360 degrees about its axis.

Each model is equipped with a discharge container. It is worth noting that this node has an independent system of rotation. This scheme provides for the deviation arrows 270-300 degrees relative to the horizontal plane. The average size of the rotor is about 20 meters in diameter. Volume bucket - about 12 liters, developing depth can reach 20-25 meters, and the height of production is equal to 50 meters.

These specifications provide a machine capacity of up to 10,000 cubic meters per hour.

VARIETY

Bucket cars qualify for the intended purpose. Thus, the trench can be identified and quarrying.

• Career excavator.

• Trenchers.

29. The process of burning cement clinker. General concepts

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.

The peculiarity of this method is that you need not take steps to ensure the artificial evaporation, and therefore en / cement costs are significantly reduced. But the maximum homogeneity of the powder mixture must be provided.

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.