FI67787B - ANLAEGGNING FOER GRANULERING AV SMAELT SLAGG - Google Patents

Description

rm ADVERTISEMENT / πηοπ [Β] (11) UTLÄGGNINGSSKRIFT 67/87 (45) Patent rt (51) Kv.ik. «/ inta. * B 01 J 2/06, C 21 B 3/06 FINLAND —FINLAND (21) Patent application - Patentansöknlng 7839 ^ 9 (22) Application date - Anxöknlngsdag 21 .1 2.78 (F ») (23) Start date - Giltlghetsdag 21.1 2.78 (41) Become public - Bllvit often tl ig 22.06.80

National Board of Patents and Registration Date of publication and hearing. -

Patent- och registrstyrelsen '' Ansökan utlagd och utl.skriften publicerad 28.02.85 (32) (33) (31) Requested privilege - Begärd priority (71) Vsesojuzny Nauchno-Issledovatelsky Institut Metallurgicheskoi Teplotekhniki, ulitsa Studenchdkask 16, S

Gosudarstvenny Sojuzny Institut po Proektirovaniju Metallurgieheskikh Zavodov, Prospekt Mira 101, Moscow, USSR (SU) (72) Mikhail Alexeevich Sharanov, Sverdlovsk, Lik Anvarovich Zainullin, Sverdlovsk, Felix Yanovich Olginsky, Moscow, Ivan Ivan ,

This invention relates to the processing and treatment of slag formed in melting furnaces and units, and in particular to a plant for the granulation of molten slag, which is intended to be used in the manufacture of slag in slag kilns and units. .

The present invention can be applied very efficiently both in the treatment of partially solidified slag transported in ladles from smelters and in the treatment of slag directly from blast furnaces and steel furnaces (e.g. converters).

Today, facilities for granulating slag are commonly used, which include a water basin, a water spray device with a chute, and an outdoor area for storing granulated slag (see, for example, SNTL Inventor Certificate No. 138,518, International Class CO4b5 / 02, 1959). Such plants are usually located far (1.5 km and above) from the smelters and the molten slag is transported there in buckets by locomotives.

2,67787

Water for granulating the molten slag is sprayed into the plant chute, into which the molten slag from the buckets is simultaneously poured. The resulting slag-water mass is sprayed into the outdoor storage area and when excess water has drained away, the slag is collected in piles, then loaded onto a railway wagon by a bucket loader and transported to users, (e.g. cement plants). The drained water drains under the influence of gravity into settling basins, which are multifaceted to enhance clarification.

Granulation of slag in such plants has the following disadvantages: - high moisture content of granulated slag, - complex circulating water supply system (many pipelines, pumps, joints, settling ponds, etc.) - risk of explosion if molten iron flows with the slag and / or if slag lumps fall into the gutter, - need for outdoor areas for granulated slag and the circulating water system and its settling basins.

A plant known next to a blast furnace for granulating slag and removing water therefrom is known in the art (see SNLT Inventive Certificate No. 529,132, International Class CO4b5 / 02, 1971), which comprises a closed water jet granulator with a chute and a pulp collection hopper with an overflow device located to remove the gutter. The hopper is connected by an air conveyor to a slag dewatering device, under which there is a basin and an outlet line for filtered water. Below the pulp collection hopper there is also a tank for clarified water, which has a pump at the bottom of the tank for supplying said clarified water to the water jet granulator. The pulp collection hopper is equipped with a screen to remove large foreign inclusions and slag lumps.

The molten slag from the blast furnace flows into a chute where it is granulated by water jets which are pumped by pressure from the tank of clarified water.

The pulp generated in the granulation enters the pulp collection hopper, 3 67787 where the granulated slag settles, while the clarified water passes over the overflow device to the clarified water tank and the pump recirculates it to the water jet granulator. The slag that settles to the bottom of the pulp hopper forms a thick pulp with water which is transported by an air conveyor to an imaging device from which the filtered water returns down the pipe to the pulp hopper, while the dry, granulated slag is conveyed by conveyor to storage or railcars. The water vapor-gas mixture formed in the granulation process is removed to the outside air.

Granulation of slag in such plants has the following disadvantages: - a protective screen is necessary in the pulp collection hopper to prevent coarse foreign entrapment and clogging of the air conveyor by slag packs. Large piles of slag, pieces of refractory pulp used in the lining of blast furnace downcomers, and other objects tend to clog such screens, causing granulated slag to deposit on top of them, all of which makes plant maintenance difficult and shortens maintenance and repair intervals.

- the need for space is relatively high, which makes it difficult to place such a plant in the limited space of existing blast furnaces. These plants are regularly built in new blast furnaces located on new construction sites.

The prior art method closest to the present invention is U.S. Pat. in patent no. 3,615,329, International Class. C03b5 / 22,1971, shown in a plant comprising a chute for feeding molten slag, a device for granulating slag with a water jet and cooling granulated slag, the device comprising a chute and pumps, and a settling basin part for coarse slag with a vertical living element with perforated buckets. The lower part of the elevator is at the lower part of the settling basin. In order to further cool and purify the water contained in the finely divided slag particles, the plant is equipped with cyclones and a water purification system comprising a cooling tower, a cooling tower basin, pumps and water supply connections.

The molten slag is fed down the chute (e.g. from a blast furnace) to a water jet granulator, where the slag is granulated by 4,67787 cold water jets fed by pumps. The slag then enters an open settling hopper, from which the settled slag is transferred to a treatment conveyor by means of an elevator. When the slag is moved by means of an elevator, water is partially removed from it. The hot water clarified in the settling hopper and suspended in the fine slag is sprayed tangentially into hydrocyclones where the slag e-rotates from the water, after which the water free of the fine slag is cooled in cooling towers and returned to the water jet granulator.

Granulation of slag in such plants has the following disadvantages: very complex water recirculation supply system (several pump groups, numerous connections, settling tanks, cooling towers for the pool, cyclones), risk of explosion if molten iron flows into the slag components are missing, water is poorly removed from the granulated slag if the water level in the elevator buckets is higher than the surface of the slag, due to fine particles suspended in the water settling on the coarser slag and preventing water runoff.

Therefore, it is an object of the invention to obviate the above-mentioned disadvantages.

The present invention is based on the provision of a plant for granulating molten slag in which a bucket elevator carrying granulated slag is positioned so that the axles of the tail and drive wheels of the elevator do not come into contact with corrosive substances in the settling basin while ensuring efficient dewatering and drying of granulated slag.

The object is achieved in a plant for granulating molten slag, comprising a device for dispersing molten slag by means of water, said device being mounted at an inlet to a settling hopper, the hopper being filled with water to a specified height. from a settling hopper characterized by a plant, the axes of the tail and traction wheels of the bucket elevator are above the water surface in the settling hopper, that the traction sheave of the bucket elevator is arranged above the tail wheel in the direction of movement of the elevator.

In this arrangement, the axles of the tail and drive wheels of the bucket elevator, which require constant maintenance, are separated from the zone of hot, corrosive mass (mixture of granulated slag and water), which is also very abrasive and tends to shrink, and allows the first stage of slag dewatering. tilting the buckets to drain the water, and the second step is to allow water to seep through the perforated walls of the bucket while the granulated slag is being transported to the unloading site and to dry the granulated slag in a dryer, all substantially increasing plant reliability by extending repair intervals and virtually looking at dry (5 ... 7% moisture content) granulated slag.

According to an embodiment of the invention, the settling bunker is closed and divided into two interconnected compartments, one for granulating the molten slag and the other for removing the granulated slag by means of a bucket elevator, the latter compartment being provided with an overflow part. Such a structure of the settling hopper ensures that the height of the water in the slag granulation compartment remains constant and makes it possible to install in said compartment an impeller with a helical housing which lifts water from the surface and throws it as a dispersing jet on the molten slag stream. The fact that the settling hopper is closed and divided into two compartments, keeping the water level in the settling bunker constant, makes the process safe from explosions and offers the possibility to purify the evolved vapor-gas mixture from sulfur-containing components by adding alkalis to the settling bunker. In this way, there is no need for a complicated water recirculation system with pump jets feeding the water jet granulator, nor does it combine the transfer of granulated slag to its dewatering, which makes the plant small and uniform in size and greatly simplifies the granulation process. This solution makes it possible to locate the plant either next to an existing or newly constructed blast furnace, whatever its production capacity, or in any separate area.

In order to improve economy and simplify granulation, it is preferable to dry the granulated slag in a rotary tumble dryer so that the fan is located at the outlet end of the dryer and the rotary feeder is mounted at the granulated slag discharge point.

The present invention will be explained in the following form of an exemplary embodiment with reference to the accompanying drawing, which shows a longitudinal vertical section of a molten slag granulation plant.

The plant according to the invention comprises a closed settling hopper 1, the wall 1 'of which divides into a compartment 2 for removing granulated slag 2' from the settling hopper 1, a granulation water tank 3 and a chamber 4 for adjusting the water level of the settling hopper 1. The compartment 2 communicates with the granulation basin 3 via an inclined channel 5 and with the chamber 4 via a channel 6 and an overflow partition wall 7. The granulation basin 3 and the chamber 4 can be located on the other two sides of the compartment 2. The basin 3 has a water jet granulator formed by an impeller 8 so that the tips of the vanes are bent in the direction of rotation. The impeller is surrounded by a helical housing 9 at a distance of 180 ... 200 °, so that the slag feed chute is located above said helical housing. The compartment 2 has an inclined bucket elevator 10 'formed by perforated buckets 11, a tail wheel 12, a traction wheel 13 and rollers 14. In order to increase the reliability of the bearings of the shafts 15, 16 and to improve the dewatering of the granulated slag, the tail and traction wheels 12 and 13 shafts 15, 16 placed above the water surface defined by the overflow partition 7. At the stern of the settling hopper 1, the compartment 2, above the water surface, becomes a drain chute 17 for supplying slag granules 2 'by gravity to a drying device comprising a rotary tumble dryer 18 connected via a closure 19 2 and to a rotatable feeder 20 which, by means of a hopper 21, guides the already dry slag granules 2 'to one of the two belt conveyors 22 for conveying the dry slag granules to the users (or to the warehouse). The stern chamber 24 is provided with a pipe 24 for supplying air from a fan (not shown) to cool and dry the granulated slag 2 '. The chamber 4 communicates with the upper manifold 27 of the water jet granulator via a pump 25 (or air conveyor) and a pipe.

7 67787

The chamber 4 has a water level regulator 28 located in a pipe 29 supplying fresh make-up water. The pipe 30, in one wall of the chamber 4, forms a backup leakage channel for water from said chamber 4. The granulation basin 3 and compartment 2 are isolated from the environment by a deck 31 comprising water vapor and gases are removed to the open air. To neutralize the evolving sulfur-containing compounds, the plant is equipped with a system (not shown) for mixing the lime milk and feeding it to the water jet granulator.

The above device works as follows.

At start-up, the settling hopper 1 is filled with water to a certain height. Before the molten slag is poured into the hopper 1 for granulation, the impeller 8 is started so that it continuously raises water from the surface of the granulation basin 3 and throws along it in the helical housing 9 as a scattering jet in space "a" delimited on two sides. In order to prevent the formation of light granulated slag and to keep the water level in the granulation basin 3 constant, a pump 35 (or air conveyor) is started to supply water from chamber 4 all the way to pipe 26 to the upper manifold 27. Excess water drains from basin 3 through channel 6 to partition 4 or with slag, is replaced by a regulator 28 by supplying fresh water through a pipe 29. In the event that too much water enters the bunker 1, it can be discharged into the sewer via the pipe 30.

After the impeller 8, the pump 25, the bucket elevator 10 'and the lime milk system have been started, the molten slag is poured along the chute 10 into a space "a" where the slag stream decomposes into particles which cool until they solidify and fall into the basin 3. No granulation compounds because lime milk is added to the granulation water. The cooled slag granules 2 'pass under the influence of gravity through the channel 5 to the compartment 2, where they are grabbed by the buckets 11 and lifted from the water, which is heated to a temperature of 85-10 ° C by the granulated slag. As the buckets 11 rotate the tail wheel 12 on the shaft 15, they tilt to an almost horizontal position with the result that water above the slag grain layer 2 'flows over the edge of the bucket 11 back into compartment 2, which is the first stage of dewatering, reducing the water content of slag granules 2' to about 25%. When the buckets 11 pass 8 67787 spring 30 ... 40 min. along the rollers 14, exits the grated slag 2 ', which is now at a temperature of about 80-100 ° C, further water, which seeps through the holes in the slag and buckets 11 so that the moisture is 10-12%, after which the buckets are tipped as they rotate the drive wheel 13 mounted on the shaft 16, and the granulated slag slides under gravity down the downcomer 17 into the rotating tumble dryer 18. The blower (not shown) feeds air to the rotating tumble dryer downstream of the tube 24 with the granulated slag. The groove, which consumes 60 ... 100 kg per ton of granulated slag, with an initial temperature of 80 ... 100 ° C, absorbs heat from the granulated slag 2 'and is saturated with water vapor, whereby the granulated slag 2' cools to a temperature of 10 ... 20 ° C and dries to a moisture content of 5 ... 7%, which is sufficient to prevent said slag from freezing during the cold season. Further reduction of the moisture content of the granulated slag 2 'by free percolation and drying at the expense of internal physical heat becomes economically disadvantageous as it requires a significant increase in the size of the equipment required (bucket elevator length 10') and air supply energy. Fuel drying of the granulated slag 2 'is firstly economically disadvantageous and secondly an excessive reduction in the moisture content of the granulated slag (less than 5%) can cause significant environmental contamination in the form of slag dust and may require packaging of the slag before transport. Because the rotary tumble dryer is inclined, its rotation causes the granulated slag 2 'to roll and move against the air flow, towards the trailing chamber 23, from where it will turn to a feed device 20 which directs it to a corresponding conveyor 22 for transport to railway wagons or granulated slag storage. . As the cover 31, the closure 19 and the casing of the settling hopper 1 close the system, the generated vapors and gases as well as the exhaust air of the dryer 18 are removed through the pipe 32 to the outside air.

Claims (3)

67787 9 A molten slag granulation plant comprising a device for decomposing molten slag by means of water, said device being mounted at an inlet leading to a settling hopper (1), the hopper being filled with water up to a certain height, the settling hopper (1) having a bucket elevator with perforated buckets 11 ) to remove granulated slag (2 ') from the settling hopper, characterized in that the axes of the tail and drive wheels (12, 13) of the bucket elevator (10') are above the water surface in the settling hopper (1), that the bucket elevator (13) arranged above the tail wheel (12) in the direction of movement of the elevator, the granulator slag (2 ') drying device being located at the point where the granulated slag (2') is removed from the settling hopper (1). Plant according to Claim 1, characterized in that the settling hopper (1) is closed and divided into two compartments (2, 3), the compartment (3) being intended for granulating molten slag and the compartment (2) being intended for removing granulated slag (21). by means of a bucket elevator (10 ') and that the overflow wall (7) is arranged in the second compartment (2). Plant according to claim 1, characterized in that the device for drying the granulated slag (21) is provided with a rotary tumble dryer (18), the fan and the rotary feeder (20) being located near the outlet end of the dryer, the rotary feeder being located where the dry granulated slag ( 21) is dismantled.