KR20150082345A - A two-stage smelting process and apparatus - Google Patents

Abstract

A two-stage meltbased smelting process for producing molten metal from a metal-containing feedstock comprises: (a) preheating the metal-containing feedstock in a preheater; and (b) heating the preheated metal- Into the melting vessel of the smelting vessel and smelting the metal-containing feed material in the melting vessel to form molten metal and off-gas. The process includes cooling and cleaning the off-gas from the smelting vessel to produce fuel gas. The preheating step (a) is 300? Containing feed material by burning at least a portion of the fuel gas supplied to the preheating step at a temperature of less than < RTI ID = 0.0 > 300 C < / RTI >

Description

[0001] A TWO-STAGE SMELTING PROCESS AND APPARATUS [0002]

The present invention relates to a two-stage process and apparatus for smelting metalliferous materials.

The term "metal-containing material" as used herein is understood to include solid-state supply materials and also to include metal-containing materials that are partially reduced within that range.

More specifically, but not exclusively, the present invention relates to a process for the production of carbon monoxide, which is preheated initially and then generated by gas generation in the melting tank, And more particularly to a two-stage meltbased smelting process and apparatus for producing molten metal from a metal-containing feedstock fed into a smelting vessel having a strong coarse / slag fountain.

In particular, and not exclusively, the present invention relates to a process and apparatus for producing molten iron by smelting iron-containing materials such as iron ore.

In particular, and not exclusively, the present invention relates to a smelting process in a smelting vessel comprising a main chamber for smelting a metal-containing material.

Known smelter-based smelting processes are commonly referred to as HIsmelt processes and are described in a substantial number of patents and patent applications filed in the name of the present applicant.

The HIsmelt process is particularly concerned with producing molten iron from iron ore or other iron-containing materials.

In the context of the manufacture of molten iron, the HIsmelt process comprises:

(a) forming a bath of molten iron and slag in a main chamber of a smelting vessel;

(b) introducing into the tank: (i) iron ore, typically in the form of iron ores, and (ii) a solid carbonaceous material, typically coal, acting as a reducing agent and energy source for the iron ore feedstock; And

(c) smelting iron ore in a vessel.

As used herein, the term "smelting " is understood to mean a thermal process in which a chemical reaction to reduce metal oxides is performed to produce molten metal.

In the HIsmelt process, a solid feed material in the form of a metal-containing material and a solid carbonaceous material is introduced into the molten bath along with a carrier gas through a number of lances, the lance passing through the sidewalls of the main chamber of the smelting vessel, Extends inwardly and is tilted with respect to the vertical to extend into the lower region of the vessel to deliver at least a portion of the solid feed material to the metal layer at the bottom of the main chamber. The solid feed material and the carrier gas penetrate the molten bath and allow the molten metal and / or slag to protrude into the space above the surface of the bath to form a transition zone. Oxygen containing gas, typically a blast of oxygen-enriched air or pure oxygen, is blown into the upper region of the main chamber of the vessel through a downwardly extending lance and the latter of the reaction gas released from the molten bath in the upper region of the vessel Causing combustion (post-combustion). The transition zone is provided with a flow of molten metal and / or slag that provides an effective medium for transferring heat energy generated by the desired amount of ascending and descending droplets or splashes or subsequent combustion of the reaction gases on the vessel Lt; / RTI >

Typically, when producing molten iron, when oxygen enriched air is used, oxygen enriched air is generated in the hot air furnace and fed to the upper region of the main chamber of the vessel at a temperature of about 1200 ° C. When industrial low temperature oxygen is used, industrial low temperature oxygen is typically supplied at ambient temperature or at a temperature close to ambient temperature into the upper region of the main chamber.

The off-gas generated by the post-combustion of the reaction gas in the smelting vessel is discharged from the upper region of the smelting vessel through the off-gas duct.

The smelting vessel includes a refractory-lined section in the hearth and a water-cooled panel in the sidewalls and roof of the main chamber of the vessel, and the water is continuously circulated through the panel in the continuous circuit.

The HIsmelt process allows a large amount of molten iron, typically at least 0.5 Mt / a, to be produced by smelting in a single small vessel.

The HIsmelt process involves solid blowing into the melting vessel in a smelting vessel through a water-cooled solid blowing lance.

In addition, a key feature of this process is that the process operates in a smelting vessel that includes a main chamber for the smelting metal-containing material and a converter connected to the main chamber through a converter connection that allows continuous metal product outflow from the vessel . The converter acts as a molten metal filled siphon seal, an excess molten metal spontaneously "spilling" out of the smelting vessel as the molten metal is created. This allows the molten metal level in the main chamber of the smelting vessel to be known and controlled within small tolerances, which is essential for plant safety. The molten metal water level must (at all times) be maintained at a safe distance below the water-cooled element, such as a solid blowing lance that extends into the main chamber, otherwise a steam explosion may occur. For this reason, the converter is considered an intrinsic part of the smelting vessel for the HIsmelt process.

The term "converter" as used herein refers to a furnace which is open to the atmosphere and which is connected to the main smelting chamber of the smelting vessel through a passageway (hereafter referred to as " The connection is understood to mean the chamber of the smelting vessel, which is completely filled with molten metal.

The present invention is partly the result of experience gained in a demonstration plant operating a HIsmelt process. These plants were built in Perth, Western Australia in 2002-2003, when natural gas prices were below $ A3 / GJ. Natural gas prices exceeded $ A8 / GJ when the first plant of this kind was fully operational in a few years. As a result, the "as built" configuration (designed for high natural gas consumption due to the original low cost) was subject to severe economic pressures.

Fluidized bed preheating of iron ore using a circulating fluidized bed in a plant (prior to blowing into the smelting vessel) is one of the more significant natural gas uses in the plant.

Fluidized bed preheater is operated with natural gas and air combustion in direct contact with iron ore to generate the heat necessary to preheat iron ore. This type of HIsmelt process is described below as a "decoupled" mode of operation, since the preheater did not utilize the available energy from the smelting vessel to preheat the iron ore.

The plant was designed to use off-gas (nominally 1000 ° C) as hot gas as fuel gas in the ore preheater. This type of HIsmelt process is described herein as a "hot-coupled" mode of operation.

Although considerable experience has been gained in the unbonded mode at the plant, the high temperature coupled mode has not been implemented at all, primarily due to concerns such as safety issues associated with carbon monoxide-containing gas leaks from the unit.

The above description is not to be construed as a general knowledge common in Australia or elsewhere.

The process and apparatus of the present invention can be used to (i) prevent risk and safety problems associated with carbon monoxide leakage in high temperature coupled mode, (ii) utilize the confidential operating experience obtained using the decoupling mode iii) Prevent the use of natural gas (or other imported fuel gas).

Unlike the prior art in the art (e. G. PCT / AU2005 / 000284, PCT / AU2007 / 000542 and PCT / AU2007 / 000534) by the Applicant, the process and apparatus of the present invention, Typically, the off gas is cooled by dissolution at a temperature of less than about 300 ° C (and typically greater than 200 ° C). In the process and apparatus of the present invention, typically all of the off-gas is collected by the melt, cooled to a significantly lower temperature, and dust is removed (e.g., in a wet scrubbing scrubber). Once cooled and cleaned, at least a portion of this gas is split for use as a fuel gas in a fluidized bed iron ore preheating unit. The process of the present invention herein is described as a "cold coupling" mode of operation.

In general, the present invention provides a method for producing a metal-containing feedstock comprising the steps of: (a) preheating a metal-containing feedstock in a preheater; and (b) blowing the preheated metal-containing feedstock and the solid carbonaceous material into a melting vessel of a smelting vessel, Based smelting based smelting process for producing molten metal from a metal-containing feedstock, comprising smelting a metal-containing feedstock in the smelting furnace to form molten metal and off-gas. The process includes cooling and cleaning the off-gas from the smelting vessel to produce fuel gas. The preheating step (a) is 300? Containing feed material by burning at least a portion of the fuel gas supplied to the preheating step at a temperature of less than < RTI ID = 0.0 > 300 C < / RTI >

A two-stage meltbased smelting process for producing molten metal from a metal-containing feedstock, comprising: (a) preheating a metal-containing feedstock in a preheater; and (b) Wherein the smelting vessel comprises a bath of molten metal in the form of molten metal and molten slag, generating a coarse / slag fraction through the generation of gas in the molten bath, Containing feedstock in a molten bath to form a molten metal, and the preheating step is performed by burning the fuel gas supplied to the preheating step (a) at a temperature of less than 300 [deg. And preheating the material, wherein the fuel gas is produced from the off-gas discharged from the smelting vessel.

The fuel gas supplied to the preheating step (a) may be at a temperature of at least 200 ° C.

The offgas discharged from the smelting vessel is typically available at pressures in the range of 0.5 to 1.0 bar gauge.

Typically, the off-gas discharged from the smelting vessel is at a significantly higher temperature than the target maximum temperature of 300 占 for the preheating step (a). In the process, the off-gas discharged from the smelting vessel is heated to 300? To < RTI ID = 0.0 > less < / RTI >

The process may include a step of cleaning the offgas prior to the preheating step (a).

One option for cooling and cleaning the off-gas is a wet scrubbing system.

Another option for cooling and cleaning the off-gas is a gas cooler leading to a dry baghouse or electrostatic precipitator (ESP).

Any other suitable cooling and cleaning option may be used.

When a wet scrubbing and dust collecting device is used, the wet scrubbing device will generally include a pressure control valve (which is used to control the pressure in the furnace). These valves, which form part of a scrubbing process, require a pressure drop of at least about 0.4 bar (at least) to achieve the required gas scrubbing. Thus, the resultant cooled and cleaned gas is available in a pressure range of about 0.1-0.6 bar g. Downstream equipment such as hot wind furnaces and waste heat boilers can operate satisfactorily with the fuel gas at the bottom of this pressure range. However, fluidized bed ore preheaters will generally require somewhat higher pressures in the fuel gas (towards the top of the range) to function correctly. If it is not possible to maintain a sufficiently high pressure in the gas main, a blower or compressor may be used to increase the pressure in the iron ore preheater section of the gas (although this is generally an undesirable and more expensive option).

If a gas cooler leading to a dry dust collector (or ESP) is used instead of a wet scrubber, the gas cooler will generally have a pressure control valve (equivalent to a wet scrubber) immediately downstream of the filter element. The pressure drop across the filtration element will typically be less than about 0.1 bar. With this kind of gas cleaning system it is possible to divide the gas after the filtering element and before the main pressure control valve so that it is only about 0.1 barg (or less) lower than the pressure in the furnace upper space, Making the gas available in the iron ore preheater. In this case, the possibility of requiring a gas blower or compressor is somewhat less, and the possibility that the system can function as a direct connection between the gas scrubber and the iron preheater is significant. However, if a high pressure drop (for gas mixing and distribution) is required in the ore preheater, a gas blower or compressor may still be required.

The "cold junction" mode of this operation essentially fulfills the three requirements described above and provides a realistic alternative to conventional HIsmelt plant gas flow configurations. This requirement prevents (i) risk and safety problems associated with carbon monoxide leakage in high temperature combined mode, (ii) utilizes the confidential operating experience obtained with the unbind mode (iii) (Or other imported fuel gas).

Such a process may include adjusting the pressure of the off-gas required in the pre-heating step.

In the context of metal-containing feedstock in the form of iron ores, the present invention provides a method of operating a two-stage smelting process utilizing a smelting vessel and an iron ore preheating unit. The smelting vessel may include a refractory-lined main chamber and a refractory-processed converter connected to the main smelting chamber through a converter connection. The process comprises the following steps:

(i) pre-heated iron ores in the form of granular coal, limestone, and iron ores, usually in the form of iron ores having a main dimension less than 6 mm, at a feed point into the ingot lance, preheated iron ores, typically at a temperature of at least 300 ° C, Accepting;

(ii) an oxygen-containing gas (typically, hot oxygen-enriched air or low-temperature industrial oxygen) is blown into the upper space of the gas in the smelting vessel in the smelting vessel so that the flammable gas in the upper space Generating heat through combustion;

(iii) generating a coarse / slag fraction through ascending and descending droplets and non-products from the molten bath so that heat is transferred from the upper space to the bath to continue the smelting reaction;

(iv) semi-continuously or continuously removing the molten iron through the converter, and periodically removing the slag through a water-cooled slag tapping device mounted on the side wall of the vessel;

(v) The off-gas discharged from the smelting vessel is about 300? ? Less than 200 and typically cooled to excess, the method comprising: removing dust particles, and generates a low-temperature clean fuel gas with a heating value of from 2 to 4 MJ / Nm ³ range (LHV basis);

(vi) directing at least a portion of the fuel gas, typically between 15% and 35% of the fuel gas, directly into the ore preheater to a temperature below about 300 ° C (if the pressure is sufficient for operation of the preheater) (If the gas pressure is not sufficient);

(vii) burning such fuel gas with air or oxygen enriched air that is in direct contact with the iron ore feedstock, typically granular iron ore, such as minute iron ore, and supplying the iron ore feedstock in the range of 600-1000? Heating to a temperature in the range; And

(viii) supplying the resulting hot metal-containing material (typically via a hot lock hopper system) into the smelting vessel described in step (i).

The present invention also relates to a two stage molten bath based smelting apparatus for producing molten metal from a metal containing feedstock, comprising: (a) a preheater for preheating the metal containing feedstock; and (b) a preheater for preheating the molten metal and molten slag Slag fraction through the generation of gas in the melting vessel, generating off-gas, smelting the preheated metal-containing feed material from the preheater in the melting vessel, A smelting vessel forming a molten metal; And (c) cooling the off-gas from the smelting vessel and cooling off-gas at a temperature of less than 300 ° C and typically greater than 200 ° C for use as a fuel gas for preheating the metal- And an off-gas treatment system for supplying the pre-heater to the preheater.

The off-gas treatment system may include a wet scrubbing device.

The off-gas treatment system may include a gas cooler leading to a dry dust collector or an electrostatic precipitator.

The off-gas treatment system may be any other suitable system.

The two-stage direct smelting process and apparatus according to the present invention will be further described by way of example only with reference to the accompanying drawings.
1 is a diagram illustrating one embodiment of a HIsmelt direct smelting system configured to operate in a "cold coupling" mode in accordance with the present invention.
Figure 2 is a diagram illustrating another embodiment of the HIsmelt direct smelting system configured to operate in the "cold coupling" mode according to the present invention, but not in only one embodiment.

Figure 1 shows a HIsmelt direct smelting process flow diagram configured to operate in a "cold junction" mode.

A metal-containing feedstock in the form of iron ore 1 (optionally mixed with some flux material) is fed into the ore preheater 2, which in this example is a circulating fluidized bed, but can be any other suitable preheater. Hot iron ore of about 850? Is removed from the bottom of the fluidized bed and fed into the hot lock hopper system 3 with a small proportion of dust from the multiclone separator 24. The hot ore is then supplied from the lock hopper system 3 to the injection lance 6 in the smelting vessel 7. The upper space pressure in the smelting vessel 7 is maintained at about 0.8 to 1.0 bar g. The hot ore reaches the feed point in the lance 6 at about 400 to 700 占 (before mixing with the coal / timber).

The coal 4 and the wood 5 are also fed into the blowing lance 6, which is first dried and pulverized in a pulverizer.

The solid blowing lance 6 blows all solids into the bath and is smelted according to the normal HIsmelt process as described above.

The molten metal 8 is discharged through a forehearth, and the slag 9 is discharged through a water-cooled slag notch.

The industrial oxygen and air 11 from the oxygen plant 10 are mixed in the hot air path 12 after compression and heated (typically) at 1200 ° C and 35 to 40 volume percent oxygen. The hot air stream 13 flows into the upper space of the smelting vessel 7 through the upper lance 22 extending vertically into the smelting vessel 7 and flows into the upper space of the smelting vessel 7 Thereby burning the process gas.

The flow of off-gas, indicated by arrows 14, discharged from the smelting vessel 7 at a high temperature (typically much higher than 1000 ° C) at a high flow rate is an off-gas treatment for cooling and cleaning the off-gas for use as a fuel gas It is processed directly in the system.

More specifically, after the hot off-gas is cooled in the hood 15, it is cleaned in a wet scrubber 16. 150 to 300? A clean gas 17 having a temperature within the range, typically a temperature of about 250 ° C and a calorific value within the range of typically 2 to 4 MJ / Nm ³ (LHV standard), is controlled to a nominal pressure of 0.4 to 0.5 bar g, , And is divided into three parts, which will be described later.

(i) Fuel gas (18), either directly delivered through the duct to the ore preheater (2) (if pressure is sufficient), or indirectly delivered through the blower or compressor (if the pressure is very low). The fuel gas 18 comprises 10 to 40%, typically 10 to 30%, and more typically 20% of the flow from the smelting vessel 7, and the heat for preheating the iron ores entering the ore pre- (In the ore preheater 2) to generate the air (19).

(ii) a fuel gas (20) used to ignite the hot air path (12).

(iii) fuel gas (21) burned in the waste heat boiler (23) for steam and power generation.

Figure 2 shows a HI smelt direct smelting system constructed in a second embodiment, but not one possible embodiment of the "cold junction" mode.

Iron ore 201 (optionally mixed with some ligneous material) is fed into ore preheater 202, which in this example is a circulating fluidized bed. High temperature iron ore of about 850? Is removed from the bottom of the fluidized bed and fed into the hot rock hopper system 203 with a small proportion of dust from the multi-clone separator 226. The hot ore is then supplied from the lock hopper system to the blowing lance 206 in the smelting vessel 207. The upper space pressure in the smelting vessel 207 is maintained at about 0.8 to 1.0 bar g. The hot ore reaches the feed point in the lance 206 at about 400 to 700 占 (before mixing with coal / timber).

The coal 204 and the wood 205 are also fed into the blowing lance 206, which is first dried and pulverized in a pulverizer.

The solid blowing lance 206 blows all solids into the bath and is smelted according to the normal HIsmelt process as described above.

The molten metal 208 is discharged through a converter, and the slag 209 is discharged through a water-cooled slag notch.

The industrial oxygen and air 211 from the oxygen plant 210 is mixed in the hot air path 212 after compression and is typically heated to 1200 ° C and 35 to 40 percent by volume of oxygen. The hot air stream 213 flows into the upper space of the smelting vessel 207 through the upper lance 228 extending vertically into the smelting vessel 207 and flows into the upper space of the smelting vessel 207 Burns the process gas.

The flow of off-gas, indicated by arrow 214, which is discharged from the smelting vessel 207 at a high flow rate at high temperature, is processed directly in an off-gas processing system that cools and cleans off-gases for use as a fuel gas.

(A) about 10 to 40%, typically 10 to 30%, of the flow from the smelting vessel 207, after cooling to about 800 to 1000 C at the hood 215, A portion 216 that more typically comprises 20%, and (b) a second portion 221 that comprises the remainder.

The gas stream 216 is then removed in the gas cooler 217 after the dust has been cooled to a temperature in the range of 150-300 ° C, typically about 250 ° C, within the baghouse 218 do. A clean gas 219 at a pressure of about 0.1 bar g lower than the pressure of the upper space of the melting furnace and a low temperature at a calorific value, typically in the range of 2 to 4 MJ / Nm ³ (LHV standard) And is directly supplied to the ore pre-heater 202.

The gas flow 221 is directed to the interior of the wet cleaning and collecting device 222 to produce a clean fuel gas flow 223 of a calorific value in the range of about 250 ° C and typically in the range of 2 to 4 MJ / Nm ³ (LHV standard) And is cleaned. These gases are then:

(i) the fuel gas 224 used to ignite the hot runner 212;

(ii) a fuel gas 225 that is burned in the waste heat boiler 230 for steam and power generation.

The above described embodiment of the HIsmelt direct smelting process configured to operate in the "cold junction" mode in accordance with the present invention effectively replaces the current operating mode for the HIsmelt process.

Various modifications may be made to the embodiments of the process of the present invention described with reference to the drawings without departing from the spirit and scope of the invention.

By way of example, although the embodiment is described in the context of a HIsmelt direct smelting process, the present invention is not limited to this, but rather extends to any two-stage smelter-based smelting process, including a metal containing feedstock preheat and smelting step .

By way of example, although the embodiments are described in the context of smelting iron ore, the present invention is not limited to such materials and can be readily understood to extend to any suitable metal-containing material.

Claims (9)

A two-stage melt-base smelting process for producing molten metal from a metal-containing feedstock,
(a) preheating the metal containing feed material in the preheater, and
(b) blowing the preheated metal-containing feedstock material and solid carbonaceous material into a smelting vessel, wherein the smelting vessel comprises a bath of molten material in the form of molten metal and molten slag, To produce a coarse / slag fraction, to generate off-gas, to refine the metal-containing feed material in the melting tank to form molten metal, Containing feedstock by burning the fuel gas supplied to the pre-heating step (a) at a temperature of less than < RTI ID = 0.0 > 100 C < / RTI > The method according to claim 1,
The off-gas discharged from the smelting vessel is 300? ≪ / RTI > 3. The method of claim 2,
(A) before the preheating step (a). The method of claim 3,
And cooling and cleaning the off-gas within the wet scrubbing apparatus. The method of claim 3,
Cooling the off-gas in a gas cooler, and cleaning the off-gas in a dry dust collector or electrostatic precipitator. 6. The method according to any one of claims 1 to 5,
And adjusting the pressure of the off-gas required in the pre-heating step. 7. The process according to any one of claims 1 to 6,
When the metal-containing feed material is iron ore, the following steps are performed:
(i) blowing granular coal, cast iron and preheated iron ores through a blowing lance into the smelting furnace;
(ii) blowing the oxygen-containing gas into the upper space of the gas in the melting vessel in the smelting vessel and generating heat through combustion of the combustible gas in the upper space to sustain the smelting reaction in the vessel;
(iii) generating a coarse / slag fraction through ascending and descending droplets and non-products from the molten bath so that heat is transferred from the upper space to the bath to continue the smelting reaction;
(iv) semi-continuously or continuously removing the molten iron through the converter, and periodically removing the slag through a water-cooled slag tapping device mounted on the side wall of the vessel;
(v) cooling the off-gas off-gas discharged from the smelting vessel to less than 300 ° C, removing dust particles, and generating low temperature clean fuel gas having a calorific value in the range of 2 to 4 MJ / Nm ³ (LHV standard) ;
(vi) supplying at least a portion of the fuel gas directly or through a pressurized blower or compressor to an ore preheater;
(vii) burning the fuel gas with air or oxygen enriched air in direct contact with the iron ore feed material, and heating the iron ore feed material to a temperature in the range of 600 to 1000 ° C; And
(viii) supplying the resulting hot metal-containing material to the smelting vessel of step (i). 8. The method of claim 7,
(vi) comprises supplying fuel gas between 15% and 35% of the fuel gas to the ore preheater. An apparatus for a two stage molten-bath-based smelting process for producing molten metal from a metal-containing feedstock,
(a) a preheater for preheating the metal containing feedstock, and
(b) a bath of molten material in the form of molten metal and molten slag, generating a coarse / slag fraction through the generation of gas in the molten bath, generating offgas, and preheating A smelting vessel for smelting the molten metal-containing feed material to form molten metal; And
(c) an off-gas treatment to cool the off-gas discharged from the smelting vessel and supply the cooled off-gas at a temperature of less than 300 [deg.] to a preheater for use as fuel gas for preheating the metal- A system comprising a system.

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