CA1174854A

CA1174854A - Production of abrasion-resistant pressed articles mainly consisting of metal

Info

Publication number: CA1174854A
Application number: CA000377493A
Authority: CA
Inventors: Franz Beckmann; Armand Wagner
Original assignee: Arbed SA
Current assignee: Arcelor Luxembourg SA
Priority date: 1980-05-19
Filing date: 1981-05-13
Publication date: 1984-09-25
Also published as: GB2075909B; FR2482625B3; AU542111B2; LU82461A1; GB2075909A; ZA813121B; DE3117184A1; BE888693A; AU7067281A; FR2482625A1; JPS5716134A

Abstract

ABSTRACT

One or more comminuted ferrous or non-ferrous metals, optionally mixed with one or more non-softening carbon-containing substances, are mixed with 10 to 40 wt.% of caking and softening hard coal. The resulting mixture is briquetted at 470 to 530°C. The components of the mixture are pre-heated so that the mixture is at the briquetting temperature, the pre-heating temperature of the hard coal being below its softening point, while the pre-heating temperature of the other components is above briquetting temperature.

Description

~174854 1.

The present invention relates to a method of producing abrasion-resistant pressed articles which consist mainly of metal and are suitable for feeding into metallurgical vessels, such as furnaces.
If materials which consist wholly or mainly of metal and which are present in a finely granulated form, such as ferro alloys (e.g. ferro-phosphorous and iron sponge, are to be subjected to a metallurgical treatment, difficulties are encountered upon charging them into blast furnaces, converters, or electrical furnaces.
lhese disadvantages may be avoided by effective compaction or briquetting.
Moreover, in foundries and metal-processing works, waste materials consisting wholly or mainly of metal are produced whose further use is desirable but is connected with technical problems. ~hus, for example, it is difficult to load fine and even coarse iron chips into a converter, electric furnace, or blast furnace without previous effective compaction or briquetting.
It would therefor be desirable to be able to convert the materials referred to above to an abrasion-resistant form which is favourable in respect of charging.
The present invention provides a process in which one or more finely granulated, shredded or otherwise . ~

' ' ' ~1~4854 comminuted metals (ferrous metals as well as non-ferrous metals may be involved, which are present alone by themselves or mixed with other substances) are mixed with a proportion of from 10 to 40 % by weight of caking and softening black or hard coal, and the mixture is briquetted at a temperature of from 470 to 530C.
Prior to mixing with the caking coal, which serves as a binding agent, the metal or metals may be mixed with one or more non-softening carbon-containing substances, such as low-volatile hard coal, coke fines, fine-grain low-temperature coke, or oil coke.
lhe invention is based on the surprising dis-covery that metallic materials may be combined with softening hard coal to form a strong and abrasion-resistant pressed article.
Although the temperature occurring in a furthermetallurgical treatment of the pressed article would be expected to lead to a high loss of strength and increased deformability of the included metal or metals, the binding agent (coal) is converted simultaneously to a stable coke structure which counteracts this loss of strength.
Additionally, in metal-producing processes in which -the pressed articles constitute all or part of the charge, the carbon originating from the binding agent serves as a heat carrier and a reducing agent.

~ 174854 Pre~erably, the metals and under certain circum-stances the non-softening carbon-containing substances, prior to mixing with the proportion of sof-tening caking hard coal and prior to briquetting, are raised to a temperature which lies above the briquetting temperature, whereas the softening caking hard coal is preferably raised to a temperature which lies below the softening point of the hard coal. ~he temperatures of the components are preferably so adjusted, prior to mlxing, that the desired briquetting temperature is obtained as the temperature of the resulting mixture.
Prior to briquetting, the mixture is preferably subjected to partial gas removal (de-gassing) during which the major proportion of the t æ yield of the binding agent (coal) is released and is removed from the mixture.
ample Shredded ferrous scrap is mixed with caking and softening hard coal and is briquetted at a temperature in the range 470 to 530~. ~he hard coal content of the mixture is 10 to 40 wt.%, while the ferrous scrap content exceeds 50 Wt./Q~
~ efore the scrap is mixed with the hard coal it is mixed with a smaller amount of non-softening carbonaceous substances, and this pre-mix is heated to a temperature higher than the biquetting temperature. lhe hard coal is also pre-heated, but to a temperature below its softening ~, .

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11748~4 4.
point. The respective temperatures are selected such that the resulting mixture is at the briquetting temperature.
~he mixture is formed in an upright mixer equipped with a stirring mechanism. In this mixer the mixture is partially de-gassed and mGst of the tar ' yield of the hard coal is removed.
Briquetting is effected by means of a roller press which operates at a compression pressure in the range 1 to 5 kg/cm roller width. After discharge from the roller press, the finished briquettes are maintained in the region of the briquetting temperature for a pro-longed period of time, at least for 30 minutes, during which their strength tends to increase.
~he pressed briquettes are charged in the hot state into the metallurgical vessel for which they are intended. In this way the cooling is saved which is otherwise required and the sensible heat of the pressed articles is made use of.

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Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A method of producing an abrasion-resistant pressed article which consists mainly of metal and is to be charged into a metallurgical vessel, the method comprising the steps of forming a mixture comprising at least one comminuted metal and 10 to 40 wt.% of caking and softening hard coal, and briquetting the mixture at a briquetting temperature in the range 470 to 530°C.

2. A method as claimed in claim 1, further comprising, before forming the said mixture, bringing the at least one comminuted metal to a temperature higher than the briquetting temperature.

3. A method as claimed in claim 1, further comprising, before forming the said mixture, bringing the said hard coal to a temperature lower than its softening point.

4. A method as claimed in claim 1, further comprising, before forming the said mixture, mixing the at least one comminuted metal with at least one non-softening carbon-containing substance.

5. A method as claimed in claim 4, further comprising, before forming the said mixture, bringing the at least one non-softening carbon-containing substance to a temperature higher than the briquetting temperature.

6. A method as claimed in claim 1, in which prior to the formation of the said mixture, individual components of the said mixture are at respective temperatures such that, after the formation of the said mixture, the temperature of the mixture is equal to the briquetting temperature.

7. A method as claimed in claim 1, further comprising partially de-gassing the said mixture prior to briquetting.

8. A method as claimed in claim 1, further comprising, after briquetting, maintening the pressed article in the briquetting temperature range for at least 30 minutes.

9. A method as claimed in claim 1, further comprising charging the article, while hot, into a metallurgical vessel.