CA2139220C - Treatment of waste - Google Patents
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- CA2139220C CA2139220C CA 2139220 CA2139220A CA2139220C CA 2139220 C CA2139220 C CA 2139220C CA 2139220 CA2139220 CA 2139220 CA 2139220 A CA2139220 A CA 2139220A CA 2139220 C CA2139220 C CA 2139220C
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- reaction zone
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Abstract
A method of treating inorganic solid waste in a bath of molten metal contained in a vessel (3) which has a space above the bath and a waste gas outlet (11) is disclosed. The method comprises injecting waste into the bath to form a primary reaction zone (13) in which there are reactions between the waste and the bath or in which the waste undergoes a change of phase to convert the waste into more readily recoverable or disposable products. The method further comprises injecting oxygen-containing gas towards the surface of the bath to form a secondary reaction zone (17) in a section of the space above the bath through which oxidisable products released from the primary reaction zone (13) flow to reach the waste gas outlet (11) in the vessel (3) and in which the oxidisable products are oxidised and the heat released by such oxidation is transferred into the bath.
Description
v ~:1.3~2ZD
.. .
-:'JVO 94/00533 PCT/AU93/00317 . ;, ;
.. i TREATMENT OF WASTE
:.
The present invention relates to the treatment of inorganic solid waste.
In particular, the present invention relates to the treatment of inorganic solid waste which is commonly referred to as "dusts" .
The term "dusts" as used herein is understood to mean any relatively finely divided particulate material and includes but is not limited to:
(a) metallic or metallic oxide containing material substantially collected by gas cleaning systems operated, for example, as a component of pyro-metallurgical production and processing; and/or s, (b) inorganic residues arising from the combination or incineration of toxic, hazardous and non- ', hazardous wastes, including fly ash, bottom ash and particulate material collected by gas s cleaning systems.
In many instances, for a range of;environmental and ! materials handling reasons it is difficult and expensive to dispose of dusts. For example, dusts often contain hazardous compounds and reQuire particular processing before disposal. In addition, dusts often contain components which, whilst valuable, cannot be recovered economically.
It is an object of the present invention to provide a method of treating dusts which alleviates the disadvantages described in the preceding paragraphs. '"
According to the present invention there is provided a method of treating inorganic solid waste in a bath of molten metal contained in a vessel which has a space above the bath and a waste gas outlet, the method comprising:
(a) injecting waste into the bath to form a primary reaction zone in which there are reactions between the waste and the bath or in which the waste undergoes a change of phase to convert the waste into more readily recoverable or disposable products; and (b) injecting oxygen-containing gas towards the surface of the bath to form a secondary reaction zone in a section of the space above the bath through which oxidisable products released from ..
the primary reaction zone flow to reach the waste Qas outlet in the vessel and in which the oxid~isable products are oxidised and the heat released by such oxidation is transferred into the bath.
It is understood that references herein to "a bath of ' a molten metal" cover a bath containing molten metal and slag as well as a bath containing molten metal only.
'30 The present invention is based partly on the realisation that a molten metal bath provides a suitable u~ environment, both in terms of temperature and composition, .< for converting inorganic solid waste, particularly dusts, E :.'.
213v 2~. ~ =--v'~WO 94/00533 PCT/AU93/00317 into more readily disposable components.,_ The present invention is also based partly on the realisation that the use of a secondary reaction zone for oxidising any oxidisable products released from the molten metal bath provides a means of minimising the energy input to maintain the temperature of the molten metal bath.
It is preferred that the method further comprises injecting a Qas into the bath to cause splashes andlor droplets of molten metal to be ejected upwardly from the bath into the secondary reaction zone or into a section of the space above the bath which is between the secondary reaction zone and the waste gas outlet to facilitate efficient heat transfer to the bath and scrubbing of volatilised species and any particulate material in the products released from the primary reaction zone and/or produced in the secondary reaction zone.
It can readily be appreciated that the combination of the oxidation of any oxidisable products in the secondary reaction zone and the scrubbing effect provided by the splashes and/or droplets of molten metal in the secondary reaction~zone or downstream thereof provides a high level of assurance against unreacted or partially reacted inorganic solid waste short-circuiting treatment altogether i and reporting in the exit gas stream from the vessel. This is achieved by providing at least two separate reaction v zones through which unreacted or partially reacted inorganic waste must pass before exiting the vessel.
It is particularly preferred that the method further y comprises injecting carbonaceous material into the bath to, form a carburising zone in which the carbon in the r carbonaceous material dissolves into the bath and is _,,:
_..
_.
.._:::
~~.3~~22, WO 94/OOS33 PCT/AU93/Of~r=r~' available for reaction with waste in the primary reaction zone.
The term carbonaceous material is herein understood to include: solid carbonaceous fuels such as coke and coal;
liquid fuels such as oil, light fuel oil, diesel oil and heavy fuel oil; and gaseous fuels, such as natural gas, methane, ethane, propane, butane; or any mixtures of the fuels.
It is preferred that the carbonaceous material be selected from one or more of the group comprising coal, spent pot linings from aluminium smelting furnaces, and sewage sludge. It is particularly preferred that the carbonaceous material comprises coal.
In the above described embodiment the heat transferred to the bath from the secondary reaction zone contributes to balancing the heat loss from the bath as a consecruence of endothermic reactions in the carburising and primary reaction zones.
One particularly preferred embodiment comprises locating the carburisinQ zone directly below the secondary reaction zone.
It ie preferred that the bath comprises at least 10%
metal. It is particularly preferred that the bath cos<priaes at least 70% metal. It is more particularly .' preferred that the bath comprises at least 80% metal.
It is preferred that the metal be selected from one or more from the group comprising iron, ferroalloys nickel, tin, chromium. silicon, and copper, and mixtures thereof.
z ~ ~ ~ z z~ ~~~, ..
,:.-.;
~'y,NO 94/00533 PCT/AU93/003i7 It is particularly preferred that the metal comprises iror_.
It is preferred that the gas injected into the b~.th to cause molten metal and slag splashes and/or droplets to be 5 ejected upwardly into the secondary reaction zone be selected from one or more of an inert gas, recycled process gas, natural gas, C02, propane, or butane, or mixtures of the gases. It is particularly preferred that the inert gas be nitrogen.
It is preferred that the oxygen-containing gas be selected from the group comprising oxygen, air and steam.
It is particularly preferred that the air be preheated. It is more particularly preferred that the air.be preheated to temperatures in the range of 900 to 1600°C.~
The present invention is described further with reference to the accompanying figure which is a schematic illustration of a preferred embodiment of a method of treating inorganic solid waste in accordance with the present invention.
The preferred embodiment of the method of the present invention is described hereinafter in the context of treating dusts although it is understood that the present invention is not so restricted and extends to the treatment t of solid inorganic waste generally.
The preferred embodiment of the method is carried out in a vessel generally identified by the numeral 3.
The vessel 3 may be of any suitable known design of metallurgical vessel with refractory lined internal walls and an outer metal shell. In the arrangement shown in the ~..
. , ., f~.'.r'..
WO 94/00533 PCi'/A~U93/00~:' ;.~ ~~
figure tre vessel 3 is a generally cylindrical shape j disposed horizontally and has bottom tuyeres 5, 7, a 1 slag/metal tap 9, an air injection port 10, and an upper off-gas outlet 11 at one end of the vessel 3. Typically, ' ;
the ratio of the length and the diameter of the vessel is 3:1.
The vessel 3 contains a volume of molten metal which comprises at least 10°% iron and a layer of slag at a temperature of 1400°C. The other metals in the bath may be selected as required and, by way of example, may comprise one or more of ferroalloys. tin, nickel, silicon and copper.
The preferred embodiment of the method comprises injecting dusts entrained in a suitable carrier, such as an inert Qas, through the bottom tuyeres 5 into the bath to form a primary reaction zone indicated schematically by the line identified by the numeral 13 which is located at the end of the vessel 3 remote from the off-gas outlet 11. The dusts undergo a range of reactions and phase changes in the primary reaction zone 13 depending on the composition of the dusts. Typically, the metal oxides in the dusts are reduced an8 the metal values report into the bath or in some cases are volatilised. Other components of the dusts t may be broken down or volatilised and released directly into the gas space above the bath.
The method also comprises iajecti: pre-heated air, s typically at a temperature in the rax~ of 900 to 1600°C, or any other suitable oxygen-contain. _~ gas through , injection port 10 towards the surface of the bath adjacent the primary reaction zone 13 to form a secondary reaction zone indicated schematically by the line identified by the , ;v~'~ W~ 94!00533 fCT/AU93/00317 ~~.::
numeral 17 in the section of the space above the bath that is located between the section that is directly above the primary reaction zone 13 and the off-gas outlet 11."
The method also comprises simultaneously injecting nitrogen or any other suitable gas through tuyeres 7 into the bath immediately below the secondary reaction zone 17 to cause eruption of molten metal and slag in splashes and/or droplets from the surface of the bath into the secondary reaction zone 17. Typically, the nitrogen is injected in an amount greater than or equal to 0.1 Nm3 min"1 tonne-1 of molten metal in the bath.
In the secondary reaction zone 17 the pre-heated air oxidises any oxidisable products from the primary reaction zone 13. Furthermore, the heat released by such oxidation is efficiently transferred to the splashes and/or droplets of molten metal and slag and subsecguently into the bath when the splashes and/or droplets fall downwardly to the surface of the bath. The splashes and/or droplets also scrub volatilised species and any particulate material from the primary reaction zone 13 and/ar formed in the secondary reaction zone 17 and transfer the scrubbed values to the bath.
It is preferred that the carbonaceous material be selected from one or more of the group comprising coal, spent pot linings from aluminium smelting furnaces, and sewage sludge. It is particularly preferred that the carbonaceous material comprises coal.
It is noted that in effect the splashes and/or droplets of molten metal and slag form a curtain which is an effective and efficient means of transferring heat to the bath and scrubbing volatilised species and particulate material from products from the primary reaction zone 13 and/or secondary reaction zone 17. ~ .
Typically, the temperature in the secondary reaction zone 17 is controlled to be at least 200°C higher than that of the molten metal. Typically, the temperature in the secondary reaction zone 13 varies between 1500°C and 2700°C.
It can be readily appreciated from the foregoing that in the preferred embodiment of the method the secondary reaction zone 17 has three important functions.
Specifically, the secondary reaction zone 17:
(a) oxidises any oxidisable products from the primary reaction zone 13;
(b) ensures that the heat released by such oxidation is transferred to the bath; and (c) scrubs any volatilised species and any particulate material from the primary reaction zone l3 and/or formed in the secondary reaction zone 17. v The preheated air may be injected into the secondary reaction zone 17 by any suitable means such as top-blowing single or multiple tuyeres or lances with one or more' ..
openings.
~ In many instances, the reduction of metal oxides in the dusts to metal values will be a dominant reaction in the .
primary reaction zone 13. As a consequence, in such v':
.1392~~
v:WO 94/00533 ., PCT/AU93/00317 situations, in order to maintain a level of carbon in the bath to reduce efficiently the metal oxides in the dusts,' the method also comprises injecting carbonaceous material such as coal into the bath through tuyeres 7 to form a carburisation zone indicated schematically by the line identified by the numeral 15. The volatiles in the coal are thermally cracked and the carbon dissolves in the iron and disperses through the bath and in particular into the primary reaction zone 13.
It is noted that the heat transfer to the bath is important since reduction reactions in the primary reaction zone I3 and the carburisation zone 15 are essentially endothermic and it is important to balance the heat loss due to such reactions to maintain the temperature of the bath at an effective operating level.
It can be readily appreciated from the foregoing.that the preferred embodiment of the method of the present invention is an efficient means by which solid inorganic waste, particularly dusts, can be converted into component parts which are non-hazardous and comparatively straight- , forward to recover. ' In addition, it can be readily appreciated that the use of two separate reaction zones in the preferred embodiment provides a high level of assurance against unreacted dusts.
which may include hazardous components, short-circuiting x:.
r:~:.
treatment altogether.
9.
J
t Many modifications may be made to the preferred ., embodiment of the method of the present invention without departing from the spirit and scope of the present invention.
In this regard, whilst in the preferred embodiment the inorganic solids and coal are injected into the batkr to form separate, essentially macro-sized, reaction and carburisation zones in the bath, it can readily be appreciated that the present invention is not so limited and the injection of the constituents into the bath can be controlled to form arrays of separate essentially micro-sized primary reaction and carburisation zones.
Furthermore, whilst the preferred embodiment includes the location of the,secondary reaction zone 17 immediately above the ca~burisation zone 15, it can readily be appreciated that the present invention is not so limited aad the secondary reaction zone 17 may be located above a section of the bath that is adjacent to the carburisation zone 15.
Furthermore, whilst~the preferred embodiment comprises injecting nitrogen or any other suitable gas into the bath to cause eruption of molten metal and slag splashes and droplets to form a curtain in the secondary reaction zone , 17, it can readily be appreciated that the present invention is not so limited. By way of example, the v curtain of splashes and droplets of molten metal and slag w may be projected into a section of the bath which is between the secondary reaction zoae 17 and the waste gas outlet 11 so that products, gaseous or solid, flowing from the secondary reaction zone 17 are reQuired to pass through the curtain before reaching the waste gas outlet 11. As a consecZuence. the curtain enables heat transfer back to the :, bath and scrubbing of volatilised species and any particulate material flowing from the secondary reaction zone 17.
-,
.. .
-:'JVO 94/00533 PCT/AU93/00317 . ;, ;
.. i TREATMENT OF WASTE
:.
The present invention relates to the treatment of inorganic solid waste.
In particular, the present invention relates to the treatment of inorganic solid waste which is commonly referred to as "dusts" .
The term "dusts" as used herein is understood to mean any relatively finely divided particulate material and includes but is not limited to:
(a) metallic or metallic oxide containing material substantially collected by gas cleaning systems operated, for example, as a component of pyro-metallurgical production and processing; and/or s, (b) inorganic residues arising from the combination or incineration of toxic, hazardous and non- ', hazardous wastes, including fly ash, bottom ash and particulate material collected by gas s cleaning systems.
In many instances, for a range of;environmental and ! materials handling reasons it is difficult and expensive to dispose of dusts. For example, dusts often contain hazardous compounds and reQuire particular processing before disposal. In addition, dusts often contain components which, whilst valuable, cannot be recovered economically.
It is an object of the present invention to provide a method of treating dusts which alleviates the disadvantages described in the preceding paragraphs. '"
According to the present invention there is provided a method of treating inorganic solid waste in a bath of molten metal contained in a vessel which has a space above the bath and a waste gas outlet, the method comprising:
(a) injecting waste into the bath to form a primary reaction zone in which there are reactions between the waste and the bath or in which the waste undergoes a change of phase to convert the waste into more readily recoverable or disposable products; and (b) injecting oxygen-containing gas towards the surface of the bath to form a secondary reaction zone in a section of the space above the bath through which oxidisable products released from ..
the primary reaction zone flow to reach the waste Qas outlet in the vessel and in which the oxid~isable products are oxidised and the heat released by such oxidation is transferred into the bath.
It is understood that references herein to "a bath of ' a molten metal" cover a bath containing molten metal and slag as well as a bath containing molten metal only.
'30 The present invention is based partly on the realisation that a molten metal bath provides a suitable u~ environment, both in terms of temperature and composition, .< for converting inorganic solid waste, particularly dusts, E :.'.
213v 2~. ~ =--v'~WO 94/00533 PCT/AU93/00317 into more readily disposable components.,_ The present invention is also based partly on the realisation that the use of a secondary reaction zone for oxidising any oxidisable products released from the molten metal bath provides a means of minimising the energy input to maintain the temperature of the molten metal bath.
It is preferred that the method further comprises injecting a Qas into the bath to cause splashes andlor droplets of molten metal to be ejected upwardly from the bath into the secondary reaction zone or into a section of the space above the bath which is between the secondary reaction zone and the waste gas outlet to facilitate efficient heat transfer to the bath and scrubbing of volatilised species and any particulate material in the products released from the primary reaction zone and/or produced in the secondary reaction zone.
It can readily be appreciated that the combination of the oxidation of any oxidisable products in the secondary reaction zone and the scrubbing effect provided by the splashes and/or droplets of molten metal in the secondary reaction~zone or downstream thereof provides a high level of assurance against unreacted or partially reacted inorganic solid waste short-circuiting treatment altogether i and reporting in the exit gas stream from the vessel. This is achieved by providing at least two separate reaction v zones through which unreacted or partially reacted inorganic waste must pass before exiting the vessel.
It is particularly preferred that the method further y comprises injecting carbonaceous material into the bath to, form a carburising zone in which the carbon in the r carbonaceous material dissolves into the bath and is _,,:
_..
_.
.._:::
~~.3~~22, WO 94/OOS33 PCT/AU93/Of~r=r~' available for reaction with waste in the primary reaction zone.
The term carbonaceous material is herein understood to include: solid carbonaceous fuels such as coke and coal;
liquid fuels such as oil, light fuel oil, diesel oil and heavy fuel oil; and gaseous fuels, such as natural gas, methane, ethane, propane, butane; or any mixtures of the fuels.
It is preferred that the carbonaceous material be selected from one or more of the group comprising coal, spent pot linings from aluminium smelting furnaces, and sewage sludge. It is particularly preferred that the carbonaceous material comprises coal.
In the above described embodiment the heat transferred to the bath from the secondary reaction zone contributes to balancing the heat loss from the bath as a consecruence of endothermic reactions in the carburising and primary reaction zones.
One particularly preferred embodiment comprises locating the carburisinQ zone directly below the secondary reaction zone.
It ie preferred that the bath comprises at least 10%
metal. It is particularly preferred that the bath cos<priaes at least 70% metal. It is more particularly .' preferred that the bath comprises at least 80% metal.
It is preferred that the metal be selected from one or more from the group comprising iron, ferroalloys nickel, tin, chromium. silicon, and copper, and mixtures thereof.
z ~ ~ ~ z z~ ~~~, ..
,:.-.;
~'y,NO 94/00533 PCT/AU93/003i7 It is particularly preferred that the metal comprises iror_.
It is preferred that the gas injected into the b~.th to cause molten metal and slag splashes and/or droplets to be 5 ejected upwardly into the secondary reaction zone be selected from one or more of an inert gas, recycled process gas, natural gas, C02, propane, or butane, or mixtures of the gases. It is particularly preferred that the inert gas be nitrogen.
It is preferred that the oxygen-containing gas be selected from the group comprising oxygen, air and steam.
It is particularly preferred that the air be preheated. It is more particularly preferred that the air.be preheated to temperatures in the range of 900 to 1600°C.~
The present invention is described further with reference to the accompanying figure which is a schematic illustration of a preferred embodiment of a method of treating inorganic solid waste in accordance with the present invention.
The preferred embodiment of the method of the present invention is described hereinafter in the context of treating dusts although it is understood that the present invention is not so restricted and extends to the treatment t of solid inorganic waste generally.
The preferred embodiment of the method is carried out in a vessel generally identified by the numeral 3.
The vessel 3 may be of any suitable known design of metallurgical vessel with refractory lined internal walls and an outer metal shell. In the arrangement shown in the ~..
. , ., f~.'.r'..
WO 94/00533 PCi'/A~U93/00~:' ;.~ ~~
figure tre vessel 3 is a generally cylindrical shape j disposed horizontally and has bottom tuyeres 5, 7, a 1 slag/metal tap 9, an air injection port 10, and an upper off-gas outlet 11 at one end of the vessel 3. Typically, ' ;
the ratio of the length and the diameter of the vessel is 3:1.
The vessel 3 contains a volume of molten metal which comprises at least 10°% iron and a layer of slag at a temperature of 1400°C. The other metals in the bath may be selected as required and, by way of example, may comprise one or more of ferroalloys. tin, nickel, silicon and copper.
The preferred embodiment of the method comprises injecting dusts entrained in a suitable carrier, such as an inert Qas, through the bottom tuyeres 5 into the bath to form a primary reaction zone indicated schematically by the line identified by the numeral 13 which is located at the end of the vessel 3 remote from the off-gas outlet 11. The dusts undergo a range of reactions and phase changes in the primary reaction zone 13 depending on the composition of the dusts. Typically, the metal oxides in the dusts are reduced an8 the metal values report into the bath or in some cases are volatilised. Other components of the dusts t may be broken down or volatilised and released directly into the gas space above the bath.
The method also comprises iajecti: pre-heated air, s typically at a temperature in the rax~ of 900 to 1600°C, or any other suitable oxygen-contain. _~ gas through , injection port 10 towards the surface of the bath adjacent the primary reaction zone 13 to form a secondary reaction zone indicated schematically by the line identified by the , ;v~'~ W~ 94!00533 fCT/AU93/00317 ~~.::
numeral 17 in the section of the space above the bath that is located between the section that is directly above the primary reaction zone 13 and the off-gas outlet 11."
The method also comprises simultaneously injecting nitrogen or any other suitable gas through tuyeres 7 into the bath immediately below the secondary reaction zone 17 to cause eruption of molten metal and slag in splashes and/or droplets from the surface of the bath into the secondary reaction zone 17. Typically, the nitrogen is injected in an amount greater than or equal to 0.1 Nm3 min"1 tonne-1 of molten metal in the bath.
In the secondary reaction zone 17 the pre-heated air oxidises any oxidisable products from the primary reaction zone 13. Furthermore, the heat released by such oxidation is efficiently transferred to the splashes and/or droplets of molten metal and slag and subsecguently into the bath when the splashes and/or droplets fall downwardly to the surface of the bath. The splashes and/or droplets also scrub volatilised species and any particulate material from the primary reaction zone 13 and/ar formed in the secondary reaction zone 17 and transfer the scrubbed values to the bath.
It is preferred that the carbonaceous material be selected from one or more of the group comprising coal, spent pot linings from aluminium smelting furnaces, and sewage sludge. It is particularly preferred that the carbonaceous material comprises coal.
It is noted that in effect the splashes and/or droplets of molten metal and slag form a curtain which is an effective and efficient means of transferring heat to the bath and scrubbing volatilised species and particulate material from products from the primary reaction zone 13 and/or secondary reaction zone 17. ~ .
Typically, the temperature in the secondary reaction zone 17 is controlled to be at least 200°C higher than that of the molten metal. Typically, the temperature in the secondary reaction zone 13 varies between 1500°C and 2700°C.
It can be readily appreciated from the foregoing that in the preferred embodiment of the method the secondary reaction zone 17 has three important functions.
Specifically, the secondary reaction zone 17:
(a) oxidises any oxidisable products from the primary reaction zone 13;
(b) ensures that the heat released by such oxidation is transferred to the bath; and (c) scrubs any volatilised species and any particulate material from the primary reaction zone l3 and/or formed in the secondary reaction zone 17. v The preheated air may be injected into the secondary reaction zone 17 by any suitable means such as top-blowing single or multiple tuyeres or lances with one or more' ..
openings.
~ In many instances, the reduction of metal oxides in the dusts to metal values will be a dominant reaction in the .
primary reaction zone 13. As a consequence, in such v':
.1392~~
v:WO 94/00533 ., PCT/AU93/00317 situations, in order to maintain a level of carbon in the bath to reduce efficiently the metal oxides in the dusts,' the method also comprises injecting carbonaceous material such as coal into the bath through tuyeres 7 to form a carburisation zone indicated schematically by the line identified by the numeral 15. The volatiles in the coal are thermally cracked and the carbon dissolves in the iron and disperses through the bath and in particular into the primary reaction zone 13.
It is noted that the heat transfer to the bath is important since reduction reactions in the primary reaction zone I3 and the carburisation zone 15 are essentially endothermic and it is important to balance the heat loss due to such reactions to maintain the temperature of the bath at an effective operating level.
It can be readily appreciated from the foregoing.that the preferred embodiment of the method of the present invention is an efficient means by which solid inorganic waste, particularly dusts, can be converted into component parts which are non-hazardous and comparatively straight- , forward to recover. ' In addition, it can be readily appreciated that the use of two separate reaction zones in the preferred embodiment provides a high level of assurance against unreacted dusts.
which may include hazardous components, short-circuiting x:.
r:~:.
treatment altogether.
9.
J
t Many modifications may be made to the preferred ., embodiment of the method of the present invention without departing from the spirit and scope of the present invention.
In this regard, whilst in the preferred embodiment the inorganic solids and coal are injected into the batkr to form separate, essentially macro-sized, reaction and carburisation zones in the bath, it can readily be appreciated that the present invention is not so limited and the injection of the constituents into the bath can be controlled to form arrays of separate essentially micro-sized primary reaction and carburisation zones.
Furthermore, whilst the preferred embodiment includes the location of the,secondary reaction zone 17 immediately above the ca~burisation zone 15, it can readily be appreciated that the present invention is not so limited aad the secondary reaction zone 17 may be located above a section of the bath that is adjacent to the carburisation zone 15.
Furthermore, whilst~the preferred embodiment comprises injecting nitrogen or any other suitable gas into the bath to cause eruption of molten metal and slag splashes and droplets to form a curtain in the secondary reaction zone , 17, it can readily be appreciated that the present invention is not so limited. By way of example, the v curtain of splashes and droplets of molten metal and slag w may be projected into a section of the bath which is between the secondary reaction zoae 17 and the waste gas outlet 11 so that products, gaseous or solid, flowing from the secondary reaction zone 17 are reQuired to pass through the curtain before reaching the waste gas outlet 11. As a consecZuence. the curtain enables heat transfer back to the :, bath and scrubbing of volatilised species and any particulate material flowing from the secondary reaction zone 17.
-,
Claims (14)
1. A method of treating inorganic solid waste in a bath of molten metal in a vessel which has a space above the bath and a waste gas outlet, the method comprising:
a) injecting inorganic solid waste into the bath to form a primary reaction zone in which there are reactions between the waste and the bath or in which the waste undergoes a change of phase to convert the waste into more readily recoverable or disposable products;
b) injecting oxygen-containing gas towards the surface of the bath to form a secondary reaction zone in a section of the space above the bath through which oxidisable products released from the primary reaction zone flow to reach the waste gas outlet and in which the oxidisable products are oxidised and the heat released by such oxidation is transferred into the bath; and c) injecting a gas into the bath to cause splashes and/or droplets of molten metal to be ejected upwardly from the bath into the secondary reaction zone or into a section of the space above the bath which is between the secondary reaction zone and the waste gas outlet to facilitate efficient heat transfer to the bath and scrubbing of volatilised species and any particulate material in the products released from the primary reaction zone and/or formed in the secondary reaction zone.
a) injecting inorganic solid waste into the bath to form a primary reaction zone in which there are reactions between the waste and the bath or in which the waste undergoes a change of phase to convert the waste into more readily recoverable or disposable products;
b) injecting oxygen-containing gas towards the surface of the bath to form a secondary reaction zone in a section of the space above the bath through which oxidisable products released from the primary reaction zone flow to reach the waste gas outlet and in which the oxidisable products are oxidised and the heat released by such oxidation is transferred into the bath; and c) injecting a gas into the bath to cause splashes and/or droplets of molten metal to be ejected upwardly from the bath into the secondary reaction zone or into a section of the space above the bath which is between the secondary reaction zone and the waste gas outlet to facilitate efficient heat transfer to the bath and scrubbing of volatilised species and any particulate material in the products released from the primary reaction zone and/or formed in the secondary reaction zone.
2. The method defined in claim 1, further comprising injecting carbonaceous material into the bath to form a carburising zone in which the carbon in the carbonaceous material dissolves into the bath and is available for reaction with waste in the primary reaction zone.
3. The method defined in claim 2, wherein the carbonaceous material is selected from one or more of the group comprising coal, spent pot linings from aluminium smelting furnaces, and sewage sludge.
4. The method defined in claim 3, wherein the carbonaceous material comprises coal.
5. The method defined in claims 2, 3 or 4, further comprising locating the carburising zone directly below the secondary reaction zone.
6. The method defined in claims 1, 2, 3, 4 or 5, wherein the bath comprises at least 10% metal.
7. The method defined in claim 6, wherein the bath comprises at least 70% metal.
8. The method defined in claim 7, wherein the bath comprises at least 80% metal.
9. The method defined in claims 1, 2, 3, 4, 5, 6, 7 or 8, wherein the metal is selected from one or more of the group comprising iron, ferroalloys, nickel, tin, chromium, silicon, and copper, and mixtures thereof.
10. The method defined in claim 1, wherein the gas injected into the bath to cause molten metal and slag splashes and/or droplets to be ejected upwardly into the secondary reaction zone is selected from one or more of an inert gas, recycled process gas, natural gas, CO2, propane, or butane, or mixtures of the gases.
11. The method defined in claim 10, wherein the inert gas is nitrogen.
12. The method defined in claims 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 or 11, wherein the oxygen-containing gas is selected from the group comprising oxygen, air and steam.
13. The method defined in claim 12, further comprising preheating the air.
14. The method defined in claim 13, wherein the air is preheated to temperatures in the range of 900 to 1600°C.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| AUPL3215 | 1992-06-29 | ||
| AUPL321592 | 1992-06-29 | ||
| PCT/AU1993/000317 WO1994000533A1 (en) | 1992-06-29 | 1993-06-29 | Treatment of waste |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2139220A1 CA2139220A1 (en) | 1994-01-06 |
| CA2139220C true CA2139220C (en) | 2005-10-04 |
Family
ID=35355442
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2139220 Expired - Fee Related CA2139220C (en) | 1992-06-29 | 1993-06-29 | Treatment of waste |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2139220C (en) |
-
1993
- 1993-06-29 CA CA 2139220 patent/CA2139220C/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| CA2139220A1 (en) | 1994-01-06 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| MKLA | Lapsed |