GB2131455A - Improvements in or relating to the production of iron in a blast furnace - Google Patents

Abstract

The invention provides a method of producing iron in a blast furnace including the steps of adding coal fines to water so as to produce a suspension of the coal fines in the water by means of a suspension agent, and injecting the suspension via a lance through a tuyere of the blast furnace.

Description

SPECIFICATION Improvements in or relating to the production of iron in a blast furnace This invention relates to the production of iron in a blast furnace, and more particularly to a method of producing iron in a blast furnace including the provision of additional fuel through the blast furnace tuyeres.

It has been proposed that fuel additional to the coke charged into the top of the blast furnace should be introduced to the blast furnace via the tuyere system in order to increase the control and efficiency of operation.

It has also been proposed that such fuel should be a coal entrained via a lance into the tuyeres of the blast furnace. However, such a proposal suffers from the disadvantage that it has often been found necessary for entrainment purposes to pulverise the coal by a grinding process and to dry the coal to transport the coal to the tuyere using air. The coal crushing and pulverising process obviously involves additional expenditure thereby increasing the operational costs and reducing the economic advantages to the blast furnaces using this as an additional fuel. In addition the drying of the pulverised coal, as well as adding to operational costs, produces a material of a combustible nature which presents considerable safety problems in storage and use.

It is an object of the present invention to overcome or substantially reduce these problems.

According to the invention there is provided a method of producing iron in a blast furnace including the steps of adding coal fines to water so as to produce a suspension of the coal fines in the water by means of a suspension agent, and injecting the suspension via a lance through a tuyere of the blast furnace.

We have found it possible to utilise as fuel, coal fines, an intermediate product of coal washing.

Thus the material may comprise froth floated fines which are readily available from the washing process of domestic or industrial coal.

The suspension agent may be a gelatinous and/or large molecule substance and may be a starch product. Materials of this kind in addition to acting as a suspension agent for the coal fines also, we believe, act as a lubricant during pumping and passage of the suspension to the blast furnace injection lance.

We have found it desirable for operational and economic efficiency to have suspensions with high concentrations of coal fines up to 65 to 75 per cent coal by weight.

The suspension may be supplied by means of pumps so arranged as to provide for the metering of the suspension to individual lances or groups of lances. A recirculating main system will be utilised in order to maintain flow of the material.

In order that the invention may be more readily understood one embodiment thereof will now be described by way of example with reference to the accompanying drawing which is a schematic representation of experimental apparatus for carrying out the supply of a suspension to a lance.

As will be seen from the diagram two 6 tonne suspension tanks having agitating impellors 2 are arranged to supply in turn to a line 3 connected to lances to the tuyeres (not shown).

In one example of use for the apparatus iilustrated, the coal fines comprised anthracite froth floated fines. Such fines arise in normal coal washing processes. The fines were less than 10 B.S. mesh (95 per cent less than 1 mm in diameter and 70 per cent less than 0.5 mm in diameter).

The suspension of the fines in the tanks was created by means of a starch product such as "Jalan" (Trade Mark) at a concentration of about 0.4 per cent by weight of the total mixture.

Sufficient fines were added to create a concentration of 65 per cent by weight. The suspension slurry so produced was injected by means of the apparatus illustrated via lances into tuyeres of a blast furnace.

A meter 4 to measure the density, hence the concentration of coal in the slurry, is incorporated in the main fuel line to the furnace. This is used to monitor and control the consistency of the slurries injected.

By means of the invention a satisfactory additional fuel can be fed via lances to the tuyeres of a blast furnace at reduced capital costs and with greater safety than with the use of ground dried coal.

Claims (Filed on 2.12.83) 1. A method of producing iron in a blast furnace including the steps of adding coal fines to water so as to produce a suspension of the coal fines in the water by means of a suspension agent, and injecting the suspension via a lance through a tuyere of the blast furnace.

2. A method as claimed in Claim 1 wherein the coal fines are froth floated fines as hereinabove defined.

3. A method as claimed in Claim 1 or 2 wherein the coal fines are less than 10 B.S. mesh.

4. A method as claimed in Claim 1, 2 or 3 wherien the suspension agent is gelatinous.

5. A method as claimed in any one of Claims 1 to 4 wherein the suspension agent is a large molecule substance.

6. A method as claimed in any one of the preceding claims wherein the suspension agent is a starch product.

7. A method as claimed in any one of the preceding claims wherein the suspension incorporates up to between 65 and 75 per cent coal by weight.

8. A method as claimed in any one of the preceding claims wherein the suspension agent constitutes about 0.4 per cent by weight of the suspension.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (9)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Improvements in or relating to the production of iron in a blast furnace This invention relates to the production of iron in a blast furnace, and more particularly to a method of producing iron in a blast furnace including the provision of additional fuel through the blast furnace tuyeres. It has been proposed that fuel additional to the coke charged into the top of the blast furnace should be introduced to the blast furnace via the tuyere system in order to increase the control and efficiency of operation. It has also been proposed that such fuel should be a coal entrained via a lance into the tuyeres of the blast furnace. However, such a proposal suffers from the disadvantage that it has often been found necessary for entrainment purposes to pulverise the coal by a grinding process and to dry the coal to transport the coal to the tuyere using air. The coal crushing and pulverising process obviously involves additional expenditure thereby increasing the operational costs and reducing the economic advantages to the blast furnaces using this as an additional fuel. In addition the drying of the pulverised coal, as well as adding to operational costs, produces a material of a combustible nature which presents considerable safety problems in storage and use. It is an object of the present invention to overcome or substantially reduce these problems. According to the invention there is provided a method of producing iron in a blast furnace including the steps of adding coal fines to water so as to produce a suspension of the coal fines in the water by means of a suspension agent, and injecting the suspension via a lance through a tuyere of the blast furnace. We have found it possible to utilise as fuel, coal fines, an intermediate product of coal washing. Thus the material may comprise froth floated fines which are readily available from the washing process of domestic or industrial coal. The suspension agent may be a gelatinous and/or large molecule substance and may be a starch product. Materials of this kind in addition to acting as a suspension agent for the coal fines also, we believe, act as a lubricant during pumping and passage of the suspension to the blast furnace injection lance. We have found it desirable for operational and economic efficiency to have suspensions with high concentrations of coal fines up to 65 to 75 per cent coal by weight. The suspension may be supplied by means of pumps so arranged as to provide for the metering of the suspension to individual lances or groups of lances. A recirculating main system will be utilised in order to maintain flow of the material. In order that the invention may be more readily understood one embodiment thereof will now be described by way of example with reference to the accompanying drawing which is a schematic representation of experimental apparatus for carrying out the supply of a suspension to a lance. As will be seen from the diagram two 6 tonne suspension tanks having agitating impellors 2 are arranged to supply in turn to a line 3 connected to lances to the tuyeres (not shown). In one example of use for the apparatus iilustrated, the coal fines comprised anthracite froth floated fines. Such fines arise in normal coal washing processes. The fines were less than 10 B.S. mesh (95 per cent less than 1 mm in diameter and 70 per cent less than 0.5 mm in diameter). The suspension of the fines in the tanks was created by means of a starch product such as "Jalan" (Trade Mark) at a concentration of about 0.4 per cent by weight of the total mixture. Sufficient fines were added to create a concentration of 65 per cent by weight. The suspension slurry so produced was injected by means of the apparatus illustrated via lances into tuyeres of a blast furnace. A meter 4 to measure the density, hence the concentration of coal in the slurry, is incorporated in the main fuel line to the furnace. This is used to monitor and control the consistency of the slurries injected. By means of the invention a satisfactory additional fuel can be fed via lances to the tuyeres of a blast furnace at reduced capital costs and with greater safety than with the use of ground dried coal. Claims (Filed on 2.12.83)

1. A method of producing iron in a blast furnace including the steps of adding coal fines to water so as to produce a suspension of the coal fines in the water by means of a suspension agent, and injecting the suspension via a lance through a tuyere of the blast furnace.

2. A method as claimed in Claim 1 wherein the coal fines are froth floated fines as hereinabove defined.

3. A method as claimed in Claim 1 or 2 wherein the coal fines are less than 10 B.S. mesh.

4. A method as claimed in Claim 1, 2 or 3 wherien the suspension agent is gelatinous.

5. A method as claimed in any one of Claims 1 to 4 wherein the suspension agent is a large molecule substance.

6. A method as claimed in any one of the preceding claims wherein the suspension agent is a starch product.

7. A method as claimed in any one of the preceding claims wherein the suspension incorporates up to between 65 and 75 per cent coal by weight.

8. A method as claimed in any one of the preceding claims wherein the suspension agent constitutes about 0.4 per cent by weight of the suspension.

9. A method as claimed in any one of the preceding claims wherein the suspension is supplied to the blast furnace by means of pumps so arranged as to provide for the metering of the suspension to individual lances or groups of lances.