US3663186A

US3663186A - Method of producing metallurgical coke

Info

Publication number: US3663186A
Application number: US6251A
Authority: US
Inventors: Platon Nesterovich Dzhaparidze; Leonid Alexeevich Drakin; Sergei Ivanovich Malyshev
Original assignee: Individual
Current assignee: Individual
Priority date: 1970-01-27
Filing date: 1970-01-27
Publication date: 1972-05-16
Anticipated expiration: 1989-05-16

Abstract

A method of manufacturing metallurgical coke, consisting in that poor-caking coal is ground, then molded at a temperature of 20*350* C., whereupon the coal briquettes are caked at 450*-600* C. under the pressure of vapor and gaseous products of the coal thermal decomposition, and are then calcined at 750*-950* C.

Description

United States Patent Dzhaparidze et al.

[ 51 May 16, 1972 METHOD OF PRODUCING METALLURGICAL COKE Inventors: Platon Nesterovich Dlhaparldu, ulitsa Uplistsikhskaya, 2; Leonid Alexeevich Drakin, ulitsa Kominterna, 39, korpus 26, kv. 45, both of Tbilisi; Sergei Ivanovich Malyshev, Panfilovsky perevlok, 3, kv. 37, Moscow, all of U.S.S.R.

Filed: Jan. 27, 1970 Appl. No.: 6,251

U.S. Cl ..44/l0 H, 44/10 K, 201/6 Int. Cl. ..Cl0l 5/00 Field of Search ..44/l0 R, l0 H, l R, 10 K;

References Cited UNITED STATES PATENTS Primary Examiner-C. F. Dees Attorney-Waters, Roditi, Schwartz & Nissen [57] ABSTRACT 5 Claims, 1 Drawing Figure METHOD OF PRODUCING METALLURGICAL COKE The invention relates to methods of producing metallurgical coke from a poor-caking coal.

Metallurgical coke is one of the main constituents of the blast furnace burden, and it finds wide application in the smelting of cast-iron, steel, and ferro-alloys.

Known in the art is a method of obtaining metallurgical coke from poor-caking coal, consisting in that coal is ground and then subjected to rapid heating with a gaseous heat carrier up to a temperature, whereat it converts into plastic state, and is molded on a cellulated or plate conveyer at a temperature of 400-420 C., the formed briquettes being fed into a continuous action oven where they are caked at a temperature of 450-600 C. and calcined at 750-95 C. (see USSR Author's Certificate No. 149091, cl. a, 22/07).

The disadvantages of the previous method are a cumbersome process sequence, and difficulties in stabilizing the process of heating and molding the coal during its conversion into plastic state, which cause discontinuities of the process and production of considerable amounts of low quality coke.

Besides, caking and calcining in one apparatus (oven) involves a complicated design of this apparatus, since said processes are carried out at different rates.

The object of the present invention is to work out new conditions of molding and caking in the method of producing metallurgical coke consisting in grinding poor-caking coal, molding it, caking the briquettes at a temperature of 450-600 C., and their calcining at 750-950 C.

In accordance with said and other objects, the invention consists in that molding is done at a temperature of -350 C. (before coal conversion into plastic state), and caking is carried out under the pressure of vapor and gaseous products of coal thermal decomposition.

Molding coal before its conversion into plastic state significantly simplifies and stabilizes this operation, owing to the fact that before converting into plastic state coal has constant physical and chemical properties, does not swell, and does not release any products of its thermal decomposition.

At the same time the use of the vapor and gas pressure while caking the coal briquettes without any air access largely improves their baking conditions, widens the temperature limits and the time range of coal plasticity, raises the steadiness and stability of the coal caking process as a whole.

The pressure of the vapor and gaseous products during the process of caking the briquettes is advisable to be kept within l-20 atm. gauge.

In case molding is done on a cellulated conveyer, it is advisable to be carried out too under the pressure of vapor and gaseous products of coal thermal decomposition, the value of this pressure being equal to that in caking.

For the purpose of utilizing the heat of the exhaust vapor and gaseous products of coal thermal decomposition, as well as the binding properties thereof, the fined coal is pitched with said products prior to moulding.

The proposed method of producing metallurgical coke is realized as follows.

The poor-caking coal is ground to a size of 0-3 mm moistened, whenever necessary, to l5-l8 percent of moisture content or pitched with the products of its thermal decomposition, molded at a temperature of 20350 C. and at atmospheric pressure to a density of 0.9-1.1 g./cm and then through a sluicing arrangement charged, together with the die molds, into a travelling oven to cake the briquettes. The caking is carried out under the pressure of the vapor and gaseous products of coal thermal decomposition. In the course of movement of the plate conveyer the coal briquettes are heated to a temperature of 450-600 C. at a rate of 2-6 per minute, which results in their caking. The oven is heated by electric heaters or a gaseous heat carrier, with a gradual increase of the oven temperature in the direction of the discharge of the baked briquettes.

In the process of baking, moisture is evaporated and products of coal thermal decomposition are released, thus building up a pressure in the oven and promoting the caking of the coal briquettes. The required value of the vapor and gas pressure is chosen on the basis of the coal nature and its physical and chemical properties.

To obtain well caked briquettes, the value of the vapor and gas pressure is recommended to be maintained within 1 20 atm. gauge, proceeding from the coal properties and the requirements demanded of the briquettes. The excess pressure of the vapor and gaseous products built up in the course of caking, is continuously relieved. At the turning point of the plate conveyer i.e. opposite the sprocket, the caked briquettes are removed together with the die mold, and are through a sluicing arrangement discharged from the oven. After discharging the die molds, the caked briquettes are subjected to further heat treatment (calcining) in ordinary continuous shaft furnaces. In the shaft furnaces the briquettes are heated to a temperature of 750-950 C.

Separation of the operations of caking and calcining, and their performance in separate apparatuses permits significantly simplifying the design of the caking apparatus,and raising its productive efficiency.

In case of carrying out the coal molding process on a cellulated conveyer under the pressure of vapor and gaseous products of coal thermal decomposition, the proposed method of producing metallurgical coke is carried out as is described below and explicated in the process diagram.

According to the diagram, coal ground to a size of 0-3 mm is through a sluicing arrangement 1 fed by worm 2 into a travelling oven 3 onto a cellulated conveyer 4. On this cellulated conveyer the coal is at a temperature of 20-350 C. compacted by a molding arrangement 5 to a density of 0.9 1.1 gJcm.

When molding coal within temperatures of 20-l00 C. the coal moisture content is advisable to be kept at 15-18 percent, water or water steam being fed at point A of worm 2. When molding coal within temperatures of l00-350 C., the coal is pitched with the products of its thermal decomposition, the excess pressure of the vapor and gaseous products being released through valve 6.

Coal briquettes continuously moved along the furnace on a cellulated conveyer are heated (baked) to a temperature of 450-600 C. at a rate of 2-6 per minute. Oven 3 is heated by electric heaters 7 or by gas with a gradual temperature rise in the direction of the discharge of the caked briquettes. As it was said earlier, in the process of caking moisture is evaporated, and products of coal thermal decomposition are released, which build up pressure in the oven and help coal caking. To obtain well caked briquettes, the pressure in the oven is advisable to be maintained within l-20 atm. gauge. The excess pressure of the vapor and gaseous products is continuously released through valves 6 and 8.

During the turn of the celluated conveyer on the sprocket the caked briquettes freely fall out from the opening cells and are through a sluicing arrangement 9 discharged from the oven. The further heat treatment (calcining) of the caked briquettes is carried out in ordinary continuously acting shaft furnaces at a temperature of 750-950 C.

The described process sequence can be realized so, that mounted in one travelling oven will be two conveyers: a cellulated conveyer whereon the coal is molded, and a plate conveyer whereon the briquettes are baked, the conditions of coal molding and briquettes caking remaining unchanged.

For better understanding of the present invention given herein are the following examples of how to realize the proposed method of producing metallurgical coke.

EXAMPLE 1 Having 632 g. of coal (moisture content 5.7 weight percent, ash content 12.86 weight percent, volatile matters content 39.42 weight percent, the plastic layer thickness 8 mm) ground to a size of 0-3 mm, added thereto were 88 g. of water, the batch being then thoroughly mixed, charged into two four-cell metal molds, and pressed in a hydraulic press at a pressure of 100 kg/cm to a density equaling l g./cm (i.e. to the volume of the whole batch equaling 720 ml).

The die molds with the pressed in coal were placed into an autoclave of 8 liter capacity, and were heated to a temperature of 550 C. at a rate of 4 per minute. When the temperature was 250 C. the pressure of the vapor and gaseous products in the autoclave rose to 10 atm. gauge. This pressure was kept up until the end of the experiment by relieving the excess pressure of the vapor and gaseous products of coal thermal decomposition. After 2 hours and 17 minutes the temperature in the autoclave reached 550 C. At this temperature caking was completed, and the pressure was released from the autoclave. After the autoclave cooled off, the die molds were taken out and the caked briquettes discharged from the molds.

Visual examination of the briquettes showed that they were well baked, porous, gray-colored, the surface of the briquettes being smooth, without any visible cracks. Two briquettes of the eight produced were tested by throwing them from a height of 2 meters onto a wooden floor. The tests have proved that one briquette stood three throwings, and another one could stand five.

The remaining six briquettes were placed into porcelain cups with a capacity of 450 ml each (two briquettes in a cup), a layer of asbestos covering them on top and fine coke being spilt thereover to prevent the briquettes from burning out. Then the cups were charged into a mufi'le furnace to heat (calcine) the briquettes to a temperature of 800 C. at a rate of 2 per minute.

EXAMPLE 2 Poor-caking coal with characteristics given in Example 1 was caked. The caking was carried out so, as is described in Example 1, with the only difference that the coal briquettes were baked in the autoclave under a pressure of the vapor and gaseous products equaling atm. gauge.

EXAMPLE 3 Caking was carried out of poor-caking coal with characteristics indicated in Example 1. The caking process was carried out so, as is described in Example 1, with the only exception that the coal briquettes were baked under a pressure of the vapor and gaseous products equaling 2 atm. gauge.

EXAMPLE 4 Poor-caking coal was baked similarly to Example 1, with the only difference that instead of moistening the coal prior to its molding, it was pitched by the vapor and gaseous products of its thermal decomposition. To realize the pitching process, the coal batch (632 g.) was placed into a Buchner funnel, which was then closed with a layer of asbestos. After that the funnel with coal was placed into an electric stove or a thermostat to be heated to a temperature of 150 C. Passed through the heated coal were the vapor and gaseous products diverted from the autoclave during the release of the excess pressure at the stage of the briquettes caking in Example 1. The pitched coal was mixed, and then subjected to molding and further treatment, as in Example 1.

The quality characteristics of the metallurgical coke obtained after calcining the baked briquettes in Examples l-4, is presented in the following table.

The strength given in the table was determined by a method consisting in that a batch of coke weighing 20 g. with a medium lump size of 9-l 3 mm was tested by throwing thereon 15 times a load of 1 kg from a height of 1 m. The strength was determined as the ratio of the work done TABLE Pressure Technical analysis, weight of vapour percent and gaseous products Exin the au- Ash Volatile I ample toclave, Moisture conmatters Porosity, Strength, number atm. g.p. content tent content percent kgJdm.

( 15 kg) to S, i.e. the surface formed as a result of the work.

As is clear from the above table, the quality characteristics of the coke produced by the proposed method complies with the principal requirements demanded of metallurgical coke (porosity 50.80 54.86 percent, strength 6.00 7.53 kgldm Although the present invention is described with reference to the preferred embodiment thereof, it stands to reason that variations and alterations are possible without diverting from the idea and scope of the invention, which will be readily understood by those skilled in the art. These variations and alterations are to be considered as within the confines of the idea and scope of the invention and the appended claims.

What we claim is l. A method of producing metallurgical coke, comprising grinding poor-caking coal, molding the thus ground coal at a temperature of 20 to 350 C. to form briquettes, caking the coal briquettes at a temperature of up to 450 to 600 C. within about 2 hours under the pressure of the vapor and gaseous products of the coal thermal decomposition, and then calcining the briquettes at a temperature of up to 750- 950 C.

2. A method as claimed in claim 1, wherein the pressure of the vapor and gaseous products is equal to l 20 atm. gauge.

3. A method as claimed in claim 1, comprising effecting the molding on a cellulated conveyor transporter under the pressure of the vapor and gaseous products of coal thermal decomposition, the latter being equal to the pressure of said products during caking the briquettes, the duration of molding being determined by that of the caking of the briquettes.

4. A method as claimed in claim 3, wherein prior to molding, the ground coal is pitched with the vapor and gaseous products of its thermal decomposition.

5. A method as claimed in claim 1, wherein prior to molding, the ground coal is pitched with the vapor and gaseous products of its thermal decomposition.

Claims

2. A method as claimed in claim 1, wherein the pressure of the vapor and gaseous products is equal to 1 - 20 atm. gauge.
3. A method as claimed in claim 1, comprising effecting the molding on a cellulated conveyor transporter under the pressure of the vapor and gaseous products of coal thermal decomposition, the latter being equal to the pressure of said products during caking the briquettes, the duration of molding being determined by that of the caking of the briquettes.
4. A method as claimed in claim 3, wherein prior to molding, the ground coal is pitched with the vapor and gaseous products of its thermal decomposition.
5. A method as claimed in claim 1, wherein prior to molding, the ground coal is pitched with the vapor and gaseous products of its thermal decomposition.