RO116078B1 - Process and installation for crushing-drying raw material in cement industry - Google Patents

Abstract

According to the invention, the process and the installation for crushing-drying raw material in cement industry ensures the crushing of raw material in two steps. During the first step, the dispensed raw material is pre-crushed in a hammer mill (7), the pre-crushed material is air-conveyed in a static separator (8) where the finished product - the powder obtained by pre-crushing - is separated from the coarse product which is introduced in a tubular mill (17) for the second milling step. The powder produced in the tubular mill (17) is collected apart, thereby increasing the capacity of the tubular mill and diminishing the specific power consumption needed for crushing the raw material.

Description

The invention relates to the process and installation of milling-drying of raw materials, from the cement industry, based on the use of their pre-grinding, in a hammer mill, with pneumatic unloading and finishing of milling, in a tubular ball mill, collection The finished product and the circulation of the drying gases having separate circuits for the two mills, can be applied in the cement industry both for the increase of capacity at the existing installations, which use tubular mills, as well as for the development of new projects.

It is known, a process of milling-drying of raw materials, which uses, for pre-shredding the material before feeding into the tubular mill, a dryer crusher with gravitational discharge. This solution has the main disadvantage of limiting the humidity of the material to the feed as well as the fact that the installation can be blocked in operation.

There is also known a milling process - drying of raw materials, which uses a hammer mill, in tandem with a tubular mill, the collection of the finished product and the circulation of the drying gases having a common circuit, for the two mills. The main disadvantage of this system is that it is applied with weight, for capacity increases to existing milling sections with raw materials with tubular mill. In addition, the two equipments are totally interdependent and cannot be operated separately.

The invention removes the above disadvantages, in that, in a first phase, the raw material is pre-milled and pre-milled in a mill, up to a granulation of O-1O mm and a humidity of 3-6%, after which the pre-milled material it is separated from the finished product, flour and remains the coarse product. The coarse product, the gravel is introduced for finishing the mill in another mill, after which it is separated and collected.

The installation for the application of the above procedure has a hammer mill, which ensures the grinding and foreshadowing of the raw material, after which it is a separator, which retains and sends the finished product collected, and the coarse product re-introduces it into another tubular mill. a conveyor belt after which the finished product is collected. The two mills have separate gas circuits and separate product collection.

The invention has the following advantages:

- allows the application of the capacity increase to the existing milling machines with tubular mill, with minimal modifications of the existing equipment;

- The granulometry of the materials fed into the tubular mill is much more uniform, the finely milled material being removed from the milling circuit of the tubular mill, thus avoiding the overcrowding of the raw materials in the tubular mill.

- the raw materials fed into the tubular mill have a lower humidity, due to the pre-drying in the hammer mill assembly - static separator, thus increasing the production capacity of the tubular mill;

- the specific consumption of electricity required for the milling of the raw materials is reduced compared to the classical process of milling the raw material in the tubular mill;

- improving the quality of the finished product by eliminating the occurrence of fractions of super-milled material in the tubular mill.

The following is an example of an embodiment of the invention, in connection with the figure representing the schematic diagram of the milling drying plant.

The drying process according to the invention uses a technological installation, consisting of metal bunkers 1, in which the raw materials are brought.

RO 116078 Bl (limestone, clay, iron ore, sand, etc.]. Bunkers 1 can be in the number of three to five. From the bunkers 1, the raw materials are dosed in the specified proportions, by two dosing tapes and unloaded. on a conveyor belt, which transports the material to the milling equipment. From a conveyor belt 3, the material 50 is discharged through a two-way flap 4, which can feed the materials on a path a, on a conveyor belt 5 which feeds a die 7 with hammers, or another way b directly into a tubular mill 17 if the mill 7 with hammers is not in operation.

The raw materials, with a grain size of O + 50 mm and an initial humidity of 6 + 12%, are fed into the mill7 with hammers, through a 6-cell lock, which prevents 55 cold air from entering the atmosphere. The raw materials are fed into the hammer mill 7, directly into a hot gas stream (280 + 350 ° C], supplied from some fans 30 of the heat exchanger of the clinker combustion section or by an auxiliary furnace 32 used. if the clinker combustion section is stopped.

In hammer mill 7, the raw materials are crushed to a grain size 6o of O + 10 mm, at the same time with a reduction of humidity to 3 + 6%.

From the hammer mill 7, the crushed material is transported pneumatically and is inserted into a static separator 8. In the static separator 8 the separation of the finished product resulted in the pre-shredding phase is ensured, - the flour - having a grinding fineness of 10 + 14% residue on the 90 μπι (R ^ g) sieve from the coarse material which is introduced in the 65 phase the second milling in a tubular mill 17.

The finished product from the static separator 8 is driven by the hot gas stream in a 10 cyclone battery, where the final product is collected. The finished product is discharged from the battery of 10 cyclones by means of screws 11 with drowned head, which at the same time ensures the sealing of the system by preventing the intake of false air. The finished product 70 collected, is transported by means of pneumatic channels 12, to the storage silo.

The gas circulation, in the circuit of the mill 7 with hammers, is provided by a centrifugal fan 13. Some of the hot gases used in the hammer mill circuit can be recirculated both in the hammer feed area and in the extraction area, 75 thus ensuring the required gas flow for pneumatic transport.

The rest of the drying gases are introduced into an electrofilter 28, which ensures their de-dusting and the collection of the finished product before the gas is discharged into the atmosphere.

The coarse, gray material is discharged from the static separator 8 through a lock 9 8 a cell and is transported to the tubular mill by means of a conveyor belt 14. A conveyor 15 is mounted on the conveyor belt 14, which allows the flow rate monitoring. material fed into the tubular mill 17. The coarse material is fed into the tubular mill by means of a pendular flap

85 in the tubular mill 17, the grinding of the coarse material resulting from the hammer mill takes place. The tubular mill is operable in the closed circuit, being provided with a dynamic separator 20. The mixture of finished product and coarse material, resulting from the tubular mill, is unloaded in an elevator 18 with cups and is fed through pneumatic grooves 19 in a dynamic separator 20. The coarse material, 90

EN 116078 Bl separated into the dynamic separator 20, it is recycled to the tubular mill supply, by means of a conveyor belt 21. The flow rate from the tubular mill separator is measured by means of a tape scale 22.

The grinding product is controlled such that the flow rate from the mill 7 with hammers and measured on the conveyor belt 14, together with the flow rate from the tubular mill 17 and measured on a conveyor belt 12, is kept constant. The finished product collected in the dynamic separator 20 is unloaded on a pneumatic duct 23 which provides transport to the storage silo.

The hot gases conveyed through the tubular mill 17 and through the dynamic separator 20, are introduced into a 24 cyclone battery, which ensures the collection of the finished product. The finished product, collected is unloaded by means of cell locks 25, on a pneumatic channel 26 and is transported to the storage silo.

The gas flow in the tubular mill circuit 17 is provided by a centrifugal fan 27. The gases in the tubular mill circuit are exhausted before being discharged to a basket 30, in an electrofilter 28. The tubular mill 17 is provided with an auxiliary furnace 30, which can supply hot gases in case the clinker combustion unit does not work. The regulation of gas flow, in the separate circuits of the two mills, is done with the help of 34 technological valves.

In order to increase the capacity of a flour milling section, provided with a tubular mill, the main modification to the existing milling section is to redesign the interior equipment of the tubular mill in the sense of modifying the type of armor in the first part of the tubular mill and establishing a new recipe for bodies grinding, which allows the grinding of a material with a granulometry smaller than the one for which it was initially considered.

Claims (2)

1. The milling process - drying of the raw materials, from the cement industry, which consists of taking, from some bunkers, the raw materials, which are dosed and unloaded on a conveyor belt, which provides the feed through a two-way funnel, of the grinding equipment, characterized in that, in a first phase, the raw material is pre-milled and pre-milled in a grinding mill, up to a grain size of □ -r 10 mm and a humidity of 3 -? 6%, followed by the pneumatic transport of the pre-coated material, in a static separator, which ensures the separation of the finished product resulting from the hammer mill, in the form of flour, then collected in a cyclone battery, by the coarse product, the gray, which is introduced for finishing the milling, in another phase, in a tubular mill, the finished product resulting from the tubular mill is separated and collected in the separator of the tubular mill and in a battery of cyclones related to the gas circuit through the tubular mill. 2. An installation for applying the process of claim 1, characterized in that, before tubular mills (17), a mill (7) with hammers is installed, which ensures the pre-grinding and preworking of the feedstock from a conveyor belt (5). , the pre-milled product from the hammer mill being pneumatically transported to the static separator (8), the finished product - flour - obtained in the hammer mill being collected RO 116078 Bl 135 into a battery (10) of cyclones and sent to a storage silo, and the coarse product, the gray, discharged from the static separator by means of a cell lock (9) is fed by a conveyor belt (14) into the mill (17) ] tubular where the milling takes place, the gas circuits and final product collection, for the two mills, being separated.