Method for the production of iron and steel

Claim 2

METHOD FOR PRODUCING IRON COMPRISING FORMING A ROTARY KILN CHARGE WHICH INCLUDES APPRECIABLE AMOUNTS OF SULFUR CONTAMINATION AND CONTAINS IRON ORE AND EXCESS SOLIDS CARBONACEOUS REDUCTANT REDUCING THE ORE IN SAID CHARGE WITH SAID CARBONACEOUS REDUCTANT IN A ROTATING KILN OPERATING SAID KILN IN THE SUBSTANTIAL ABSENCE OF ADDED SLAG-FORMING MATERIALS OR WITH A LIMITED AMOUNT OF SUCH MATERIALS FOR MAINTAINING AN ACID CONDITION IN THE CHARGE AS THE ORE IS REDUCED AND REMOVING SULFUR FROM THE CHARGE IN THE FORM OF AT LEAST ONE GASEOUS OXIDE OF SULFUR INCLUDING SO AND SO2 IN THE OFF GASES DISCHARGED FROM SAID KILN SELECTING THE CHARGE TO THE KILN AND CONTRLLING KILN OPERATING CONDITIONS FOR INHIBITING THE FORMATION OF SINTER OR NODULES IN THE KILN EFFLUENT FOR PRODUCING AT TEMPERATURES IN THE RANGE OF ABOUT 600* TO ABOUT 1300*C AND LESS THAN THE FUSION TEMPERATURE OF THE INGREDIENTS OF THE ROTARY KILN CHARGE A KILN EFFLUENT WHEREIN THE MAJOR SOLID INGREDIENTS ARE UNSINTERED AND UNNODULIZED REDUCED IRON AND GANGUE MAINTAINING THE KILN EFFLUENT IN THE AFORESAID TEMPERATURE RANGE UNTIL IT HAS BEEN TRANSFERRED TO A SEPARATE MELTING ZONE WHICH IS CONNECTED WITH THE ROTARY KILN MELTING SAID EFFLUENT BY CONTACT WITH GASEOUS PRODUCTS OF COMBUSTION OF SOLID CARBONACEOUS FUEL AND/OR FLUID FUEL CAUSING THE RESULTANT SLAG TO FLOW UPWARDLY IN SAID MELTING ZONE FROM THE MELTING EFFLUENT WHILE CAUSING THE RESULTANT MOLTANT MOLTEN IRON TO ETTLE DOWNWARDLY THEREFROM AND RECOVERING THE IROM FROM SAID MELTING ZONE IN MOLTEN FORM.

Claim 3

Method in accordance with claim 1 wherein a connecting chute is provided for transferring kiln effluent from said rotary kiln to said melting zone and said chute is maintained at least partially filled with unmelted effluent for impeding the passage of gases through said chute.

Claim 4

A method in accordance with claim 1 wherein the hot rotary kiln effluent is transferred to a separate melting zone having two hearths, the first hearth being situated at a higher level than the second and communicating with the latter through conduit means; a pile of said effluent is formed in the first hearth; the flames and gaseous products of combustion of forced draft burners burning solid carbonaceous fuel and/or fluid fuel are impinged directly upon said pile of said effluent in said first hearth; the resultant combustion gases and melting or molten effluent are conveyed through said conduit means to said second hearth; and a bath of molten iron with an overlying layer of slag is formed in said second hearth.

Claim 5

Method in accordance with claim 3 wherein the base of the pile of effluent formed in said first hearth is maintained at or above the normal level of the bath of molten iron and slag which is formed in said second hearth.

Claim 6

Method in accordance with claim 3 wherein the combustion gases conveyed through said conduit means to said second hearth are guided over the surface of the bath of molten iron and slag formed in said second hearth for heating said bath.

Claim 7

A method in accordance with claim 1 wherein said steel production furnace is an electric furnace and the molten iron is heated during its conversion to steel by electric power therein, whereby savings in electric power may be obtained.

Claim 8

A method in accordance with claim 6 wherein said rotary kiln, melting zone and electric furnace are colocated.

Claim 9

Method for producing iron comprising forming a rotary kiln charge which includes appreciable amounts of sulfur contamination and contains iron ore and excess solid carbonaceous reductant; reducing the ore in said charge with said carbonaceous reductant in a rotating kiln; operating said kiln in the substantial absence of added slag-forming materials or with a limited amount of such materials for maintaining an acid condition in the charge as it reduces and removing sulfur from the charge in the form of at least one gaseous oxide of sulfur including SO and SO2 in the off-gases discharged from said kiln; selecting the charge to the kiln, and controlling kiln operating conditions, for inhibiting the formation of sinter or nodules in the kiln effluent for producing, at temperatures in the range of about 600* to about 1300* C and less than the fusion temperature of the ingredients of the rotary kiln charge, a kiln effluent wherein the major solid ingredients are unsintered and unnodulized reduced iron and gangue; maintaining the kiln effluent in the aforesaid temperature range until it has been transferred to a separate melting zone which is connected with the rotary kiln; providing a connecting chute for transferring kiln effluent from said rotary kiln to said melting zone and maintaining said chute at least partially filled with unmelted effluent for impeding the passage of gases through said chute; transferring said kiln effluent through said chute to a separate melting zone having two hearths, the first hearth being situated at a higher level thaN the second and communicating with the latter through conduit means; forming a pile of effluent in the first hearth; impinging directly upon said pile of effluent in said first hearth the flames and gaseous products of combustion of forced draft burners burning solid carbonaceous fuel and/or fluid fuel; conveying the resultant combustion gases and melting or molten effluent through said conduit means through said second hearth; forming a bath of molten iron with an overlying layer of slag in said second hearth; and recovering the iron from said melting zone in molten form.

Claim 10

Method for producing iron comprising forming a rotary kiln charge which includes appreciable amounts of sulfur contamination and contains iron ore and excess solid carbonaceous reductant; reducing the ore in said charge with said carbonaceous reductant in a rotating kiln; operating said kiln in the substantial absence of added slag-forming materials or with a limited amount of such materials for maintaining an acid condition in the charge as it reduces and removing sulfur from the charge in the form of at least one gaseous oxide of sulfur including SO and SO2 in the off-gases discharged from said kiln; selecting the charge to the kiln, and controlling kiln operating conditions, for inhibiting the formation of sinter or nodules in the kiln effluent for producing, at temperatures in the range of about 600* to about 1300* C and less than the fusion temperature of the ingredients of the rotary kiln charge, a kiln effluent wherein the major solid ingredients are unsintered and unnodulized reduced iron and gangue; maintaining the kiln effluent in the aforesaid temperature range until it has been transferred to a separate melting zone which is connected with the rotary kiln; providing a connecting chute for transferring kiln effluent from said rotary kiln to said melting zone and maintaining said chute at least partially filled with unmelted effluent for impeding the passage of gases through said chute; transferring said kiln effluent through said chute to a separate melting zone having two hearths, the first hearth being situated at a higher level thaN the second and communicating with the latter through conduit means; forming a pile of effluent in the first hearth; impinging directly upon said pile of effluent in said first hearth the flames and gaseous products of combustion of forced draft burners burning solid carbonaceous fuel and/or fluid fuel; conveying the resultant combustion gases and melting or molten effluent through said conduit means through said second hearth; forming a bath of molten iron with an overlying layer of slag in said second hearth; and recovering the iron from said melting zone in molten form.

Claim 11

Method for producing iron, comprising forming a rotary kiln charge containing iron ore, solid carbonaceous reductant and appreciable amount of SiO2, and which may also include CaO, wherein the carbon to iron weight ratio is in the range of about 0.4 to about 0.9, wherein the ratio of CaO to SiO2 is in the range of about 0.5 or less, and wherein said charge includes sulfur and/or phosphorus contamination, based on the weight of iron in the charge, of: (a) more than about 0.1% to about 2.7% of sulfur; or (b) more than about 0.1% to about 3% of phosphorus; or (c) both phosphorus and sulfur with at least one of them being in the respective range indicated, said charge further comprising less than 55% of iron and about 5 to about 65% by weight of gangue; reducing the ore in said charge with said carbonaceous reductant in a rotating kiln while (A) operating said kiln in the substantial absence of added slag-forming materials or with a limited amount of such materials for maintaining an acid condition in the charge and promoting removal of any sulfur from the charge as sulfur oxide and sulfur dioxide in the off-gases of the kiln, and (B) controlling kiln conditions to inhibit formation of sinter and nodules for producing a solid kiln effluent containing reduced iron, ashes, gangue and unburned carbonaceous reductant, maintaining the kiln effluent in the aforesaid temperature range until it has been transferred to a separate melting zone which is connected with the rotary kiln; melting said effluent by contact with gaseous products of combustion of solid carbonaceous fuel and/or fluid fuel; causing the resultant slag to flow upwardly in said melting zone from the melting effluent, while causing the resultant molten iron to settle downwardly therefrom; and recovering the iron from said melting zone in molten form.

Claim 12

Method for producing iron, comprising forming a rotary kiln charge containing iron ore, solid carbonaceous reductant and appreciable amount of SiO2, and which may also include CaO, wherein the carbon to iron weight ratio is in the range of about 0.4 to about 0.9, wherein the ratio of CaO to SiO2 is in the range of about 0.5 or less, and wherein said charge includes sulfur and/or phosphorus contamination, based on the weight of iron in the charge, of: (a) more than about 0.1% to about 2.7% of sulfur; or (b) more than about 0.1% to about 3% of phosphorus; or (c) both phosphorus and sulfur with at least one of them being in the respective range indicated, said charge further comprising less than 55% of iron and about 5 to about 65% by weight of gangue; reducing the ore in said charge with said carbonaceous reductant in a rotating kiln while (A) operating said kiln in the substantial absence of added slag-forming materials or with a limited amount of such materials for maintaining an acid condition in the charge and promoting removal of any sulfur from the charge as sulfur oxide and sulfur dioxide in the off-gases of the kiln, and (B) controlling kiln conditions to inhibit formation of sinter and nodules for producing a solid kiln effluent containing reduced iron, ashes, gangue and unburned carbonaceous reductant, maintaining the kiln effluent in the aforesaid temperature range until it has been transferred to a separate melting zone which is connected with the rotary kiln; melting said effluent by contact with gaseous products of combustion of solid carbonaceous fuel and/or fluid fuel; causing the resultant slag to flow upwardly in said melting zone from the melting effluent, while causing the resultant molten iron to settle downwardly therefrom; and recovering the iron from said melting zone in molten form.

Claim 13

A method of producing steel wherein molten iron produced in accordance with claim 9 is transferred to an arc type electric furnace for final adjustment in composition.