Method of processing electric arc furnace dust and providing fuel for an iron making process

The present invention provides a method for processing environmentally undesirable materials including petroleum coke and the sulfur and heavy metals contained therein and agglomerated waste dust from an electric arc furnace and the zinc, cadmium, lead and iron oxides contained therein and of providing fuel and a charging material for a process of making molten iron or steel preproducts and reduction gas in a melter gasifier. Metallized arc furnace waste dust material from a reduction furnace is introduced into the melter gasifier. The petroleum coke, oxygen and metallized waste dust material are reacted to produce reduction gas and molten iron from the iron oxides in the waste dust material. The molten iron contains the metals freed from combustion of the petroleum coke. The reduction gas is removed from the melter gasifier for use in the reduction furnace to produce an top off gas containing vapors of zinc, cadmium and lead.

BACKGROUND OF THE INVENTION 
The invention relates to a method for processing environmentally 
undesirable materials including petroleum coke and the sulfur and heavy 
metals contained therein and waste dust from an electric arc furnace and 
the cadmium, lead, zinc and iron oxide contained therein to provide fuel 
and a charging material for a process of making molten iron or steel 
preproducts and reduction gas in a melter gasifier. 
Electric arc furnaces utilize scrap to make steel products. Scrap iron or 
steel typically has zinc, cadmium and lead contained therein. These 
materials cause a disposal problem when the scrap steel is processed in an 
electric arc furnace. The zinc, cadmium and lead are collected in a waste 
material known as electric arc furnace dust. Electric arc furnace dust is 
classified as a hazardous waste material and heretofore has been disposed 
of in hazardous waste dumps. It has been estimated that there are 
approximately 2 million tons per year of electric arc furnace dust 
accumulated in the United States. Disposal of electric arc furnace dust in 
a hazardous waste dump may cost upwards of $150 to $200 per ton. 
Petroleum coke is a product of refinery operations and is produced in the 
United States utilizing three types of coke processing technology. 
Specifically these technologies as known to one skilled in the art are 
delayed, fluid and flexi. By far most petroleum coke in the United States 
is produced using delayed technology. In 1990, according to the U.S. 
Department of Energy, 55 refineries in the United States which had coking 
facilities and a refinery capacity of 8 million barrels per day produced 
slightly over 76,000 short tons per day of petroleum coke. The residual 
petroleum coke produced amounted to about 6% by weight of each barrel of 
crude oil processed by the refineries. 
Petroleum coke is generally the bottom end of refinery operations after 
most of the light ends and oils have been recovered from the original 
crude. The make up of petroleum coke will vary depending on a number of 
factors including the crude being processed and the process being 
utilized. Generally on a dry basis petroleum coke will be composed largely 
(approximately 90%) of fixed carbon and typically include sulfur (0.05% to 
6%) and nitrogen (2% to 4%). Various metals typically Including vanadium, 
iron and nickel are found in petroleum coke. Usually, a typical petroleum 
coke contains about 10% volatile matter. Petroleum coke contains up to 10 
to 15% moisture before drying. 
Petroleum coke is produced either as blocky sponge coke or needle coke from 
delayed cokers or in a shot size form from fluid bed cokers. Sponge coke 
from delayed cokers is by far the most important coke produced in the 
United States. Calcined sponge coke is used primarily in the manufacture 
of graphite electrodes, anodes and shaped products. Approximately 
one-fourth of the sponge coke production is used in these products. 
Until recent years the remainder of the petroleum coke in the U.S. was used 
as fuel for power plants and cement kilns. However due to the high sulfur 
content, the need for blending with coal to maintain ignition and flame 
stability and environmental problems , petroleum coke has become less 
suitable as a boiler fuel. The high sulfur content of petroleum coke also 
poses problems for cement kilns. Excess sulfur will cause finished 
concrete to expand and crack and also influences setting time. The high 
vanadium content also poses refractory problems. Thus there is a 
substantial amount of excess petroleum coke which must be disposed- The 
high sulfur content and the relatively high amounts of metals such as 
vanadium and nickel make such disposal a real environmental problem which 
the present invention is directed to solving. 
U.S. Pat. No. 4,849,015 to Fassbinder et al. discloses a method for 
two-stage melt reduction of iron ore, in which iron ore is prereduced 
substantially to wustite and at the same time melted down in a melting 
cyclone, and then liquid hot metal is produced in an iron bath reactor 
connected to the outlet of the melting cyclone and receiving the melted 
wustite by adding carbonaceous fuels and oxidizing gas to the melt. The 
resulting reaction gas from the melt is afterburned, and the dust-laden, 
partly burned reaction gases from the iron bath reactor are accelerated 
and further afterburned by adding a hot blast with a temperature of 
800.degree. C. to 1500.degree. C., and at least a portion of such 
accelerated, after burned reaction gases are introduced into the melting 
cyclone to reduce and melt fresh iron ore. 
Carbonaceous fuels, such as coke, carbonized lignite, petroleum coke, etc., 
but preferably coal of varying quality, are fed to the melt in the iron 
bath reactor. Slag-forming additives, such as lime, fluorspar, etc., are 
also fed to the iron melt to set the desired slag composition. Although it 
is irrelevant for the present invention whether these substances are 
introduced into the melt on the bath surface or from below the bath 
surface, it is preferable to add them through underbath feed nozzles. 
U.S. Pat. No. 4,806,158 to Hirsch et al. discloses a process for the 
production of reduced iron oxide-containing materials. Iron oxide and 
solid carbonaceous reducing agent are charged into a first expanded 
fluidized bed, which is supplied with an oxygen-containing fluidizing gas. 
The gas residence time selected is controlled in the reactor containing 
the first fluidized bed so that the reduction potential will result in a 
reduction of the iron oxide material not in excess of the FeO stage. A 
gas-solids suspension discharged from the first fluidized bed is supplied 
to a second expanded fluidized bed, which is supplied with a strongly 
reducing fluidizing gas. Strongly reducing gas and a major portion of the 
resulting devolatilized carbonaceous material are discharged from the 
upper portion of the second fluidized bed. Reduced material having a 
metallization of 50 to 80% and the remaining devolatilized carbonaceous 
material are discharged from the lower portion of the second fluidized 
bed. Suitable carbonaceous materials include all coals, from anthracite to 
lignite, carbonaceous minerals and waste products, such as oil shale, 
petroleum coke or washery refuse, provided that they are solid at room 
temperature. The oxygen-containing gas preferably consists of oxygen or of 
oxygen-enriched air. 
U.S. Pat. No. 4,897,179 to Mori et al. provides a method of producing 
reduced iron and light oil from iron ore and heavy oil which comprises a 
thermal cracking step of subjecting heavy oil to thermal cracking while 
retaining iron ore particles in a fluidized state to produce light oil and 
simultaneously to deposit coke as by-product on the surface of the iron 
ore particles; a gasification step of putting the coke-deposited ore in 
contact with an oxidizing gas including steam and oxygen in a fluidized 
state to react the coke with the gas thereby to produce a reducing gas 
containing hydrogen and carbon monoxide and of heating the coke-deposited 
ore upward of a reduction temperature of iron ore by partial oxidization 
of the coke; and a reduction step of reducing the coke-deposited iron ore 
in a fluidized state by the reducing gas to produce reduced iron. When the 
gasification step is performed by an oxidizing gas containing a majority 
of steam and up to 15 vol. %, based on the steam, of oxygen at 
800.degree.-1000.degree. C. under a pressure of 0-10 kg/cm.sup.2 G, a 
reducing gas containing high-concentration hydrogen gas is obtained. 
Slags of high sulfur capacity have been utilized in applications associated 
with ferrous metallurgy. Kleimeyer et al. in U.S. Pat. No. 4,600,434 
describe the use of high sulfur capacity slag and magnesium metal to 
desulfurize molten iron while it is contained in a torpedo car. Quigley, 
U.S. Pat. No. 4,853,034, describes using a vanadium-bearing, high-magnesia 
synthetic calcium aluminate slag for absorbing sulfur during ladle 
refining of steel. Knauss et al., U.S. Pat. No. 4,695,318, describe using 
a synthetic slag similar to that of U.S. Pat. No. 4,853,034, and the 
refractory brick of the ladle itself, to desulfurize molten iron contained 
in said ladle. 
In recent years methods utilizing a melter gasifier have been developed to 
produce molten iron or steel preproducts and reduction gas. Most of these 
processes utilize a coal fluidized-bed. A high temperature is produced in 
the melter gasifier utilizing coal and blown in oxygen to produce a 
fluidized bed and iron sponge particles are added from above to react in 
the bed to produce the molten iron. 
Thus in European Patent B1-0010627, a coal fluidized-bed with a 
high-temperature zone in the lower region is produced in a melter 
gasifier, to which iron sponge particles are added from above. On account 
of the impact pressure and buoyancy forces in the coal fluidized-bed, iron 
sponge particles having sizes greater than 3 mm are considerably braked 
and substantially elevated in temperature by the heat exchange with the 
fluidized bed. They impinge on the slag layer forming immediately below 
the high-temperature zone at a reduced speed and are melted on or in the 
same. The maximum melting performance of the melter gasifier, and thus the 
amount and temperature of the molten iron produced, not only depends on 
the geometric dimensions of the melter gasifier, but also are determined 
to a large extent by the quality of the coal used and by the portion of 
larger particles in the iron sponge added. When using low-grade coal, the 
heat supply to the slag bath, and thus the melting performance for the 
iron sponge particles, decline accordingly. In particular, with a large 
portion of iron sponge particles having grain sizes of about 3 mm, which 
cannot be heated to the same extent as smaller particles by the coal 
fluidized-bed when braked in their fall and which, therefore, necessitate 
a higher melting performance in the region of the slag layer, the reduced 
melting performance has adverse effects in case low-grade coal is used. 
A melter gasifier is an advantageous method for producing molten iron or 
steel preproducts and reduction gas as described in U.S. Pat. No. 
4,588,437. Thus there is disclosed a method and a melter gasifier for 
producing molten iron or steel preproducts and reduction gas. A first 
fluidized-bed zone is formed by coke particles, with a heavy motion of the 
particles, above a first blow-in plane by the addition of coal and by 
blowing in oxygen-containing gas. Iron sponge particles and/or pre-reduced 
iron ore particles with a substantial portion of particle sizes of more 
than 3 mm are added to the first fluidized-bed zone from above. A melter 
gasifier for carrying out the method is formed by a refractorily lined 
vessel having openings for the addition of coal and ferrous material, 
openings for the emergence of the reduction gases produced, and openings 
for tapping the metal melt and the slag. Pipes or nozzles for injection of 
gases including oxygen enter into the melter gasifier above the slag level 
at at least two different heights. 
Another process utilizing a melter gasifier is described in U.S. Pat. No. 
4,725,308. Thus there is disclosed a process for the production of molten 
iron or of steel preproducts from particulate ferrous material as well as 
for the production of reduction gas in the melter gasifier. A 
fluidized-bed zone is formed by coke particles upon the addition of coal 
and by blowing in oxygen-containing gas by nozzle pipes penetrating the 
wall of the melter gasifier. The ferrous material to be reduced is 
introduced into the fluidized bed. In order to be able to produce molten 
iron and liquid steel preproducts in a direct reduction process with a 
lower sulfur content of the coal used, the ferrous material to be reduced 
is supplied closely above the blow-in gas nozzle plane producing the 
fluidized bed. An arrangement for carrying out the process includes a 
melter gasifier in which charging pipes penetrating its wall are provided 
in the region of the fluidized-bed zone closely above the plane formed by 
the nozzle pipes. The ferrous material to be melted as well as the dusts 
separated from the reduction gas and, if desired, fluxes containing 
calcium oxide, magnesium oxide, calcium carbonate and/or magnesium 
carbonate are introduced therethrough. 
There is also a process known as the COREX.RTM. process (COREX.RTM. is a 
trademark of Deutsche Voest-Alpine Industrieanlagenbau GMBH and 
Voest-Alpine Industrieanlagenbau). This process is described in Skilling's 
Mining Review, Jan. 14, 1989 on pages 20-27. In the COREX.RTM. process the 
metallurgical work is carried out in two process reactors: the reduction 
furnace and the melter gasifier. Using non-coking coals and iron bearing 
materials such as lump ore, pellets or sinter, hot metal is produced with 
blast furnace quality. Passing through a pressure lock system, coal enters 
the dome of the melter gasifier where destructive distillation of the coal 
takes place at temperatures in the range of 1,100.degree.-1,150.degree. C. 
Oxygen blown into the melter gasifier produces a coke bed from the 
introduced coal and results in a reduction gas consisting of 95% 
CO+H.sub.2 and approximately 2% CO.sub.2. This gas exits the melter 
gasifier and is dedusted and cooled to the desired reduction temperature 
between 800.degree. and 850.degree. C. The gas is then used to reduce lump 
ores, pellets or sinter in the reduction furnace to sponge iron having an 
average degree of metalization above 90%. The sponge iron is extracted 
from the reduction furnace using a specially designed screw conveyor and 
drops into the melter gasifier where it melts to the hot metal. As in the 
blast furnace, limestone adjusts the basicity of the slag to ensure sulfur 
removal from the hot metal. Depending on the iron ores used, SiO.sub.2 may 
also be charged into the system to adjust the chemical composition and 
viscosity of the slag. Tapping procedure and temperature as well as the 
hot metal composition are otherwise exactly the same as in a blast 
furnace. The top gas of the reduction furnace has a net calorific value of 
about 7,000 KJ/Nm.sup.3 and can be used for a wide variety of purposes. 
The fuels used in these processes are typically described as a wide variety 
of coals and are not limited to a small range of coking coal. The 
above-noted article from Skilling's Mining Review notes that petroleum 
coke suits the requirements of the COREX.RTM. process. Brown coal and 
steam coal which are relatively poor quality coal having a relatively high 
ash content i.e. plus 15%, have been identified as suitable for use in 
these processes. Coke made from coal has also been identified as a fuel 
for many of the processes utilizing melter gasifiers. 
RELATED APPLICATIONS 
This application is a related to applications Ser. No. 07/958,043 filed 
Oct. 6, 1992; Ser. No. 07/991,914, filed Dec. 17, 1992, and Ser. No. 
08/056,341, filed Apr. 30, 1993. 
SUMMARY OF THE INVENTION 
The present invention is directed to a solution for the disposal of two 
environmentally objectionable materials and provision of a new and 
unexpectedly superior fuel source and of a ferrous material source for 
processes utilizing melter gasifiers to make molten iron or steel 
preproducts. 
In accordance with the invention it has been found that petroleum coke 
makes an excellent source of carbon in processes making molten iron or 
steel preproducts in which a melter gasifier unit is used. Further, 
electric arc furnace dust provides a source of iron oxide which can be 
converted to molten iron as well as non-ferrous heavy metal oxides of 
zinc, cadmium and lead which can be concentrated and recovered in the 
process. Moreover, the reaction in these processes utilizing the petroleum 
coke as a fuel in the melter gasifier tends to combust the petroleum coke 
substantially completely with hot reduction gas as the only gaseous 
product. The hot reduction gas from the molten gasifier at 850.degree. C. 
is recycled to the primary reduction furnace where the iron oxide in the 
electric arc furnace dust is metallized and the oxides of zinc, cadmium 
and lead are reduced to metal and vaporized. The top off gas from the 
reduction furnace contains the metallized vapors of the zinc, cadmium and 
lead from the electric arc furnace dust. When the top off gas is scrubbed 
with water, the zinc, cadmium and lead are recovered in the gas washer 
sludge at concentrations up to 50% for metal recycle and refining. 
Residual sulfur from the petroleum coke is discharged as a sulfide in the 
slag formed in the melter gasifier and is removed and disposed of with the 
slag. Heavy metals from the petroleum coke are carried over in stable form 
in solution in the molten iron or steel preproducts and will solidify 
therewith. 
In a broad aspect, the invention provides a method for processing 
environmentally undesirable materials including petroleum coke and the 
sulfur and heavy metals contained therein and waste dust from an electric 
arc furnace and the zinc, cadmium, lead and iron oxides contained therein 
and of providing fuel and a charging material for a process of making 
molten iron or steel preproducts and reduction gas in a melter gasifier. A 
melter gasifier is provided and has an upper fuel charging end, a 
reduction gas discharging end, a lower molten metal and slag collection 
end. Entry means are provided for charging material into the melter 
gasifier. Petroleum coke is introduced into the melter gasifier at the 
upper fuel charging end. Oxygen-containing gas is blown into the petroleum 
coke to form at least a first fluidized bed of coke particles from the 
petroleum coke. Arc furnace waste dust material is agglomerated and 
charged into the reduction furnace through the entry means. Petroleum coke 
and oxygen are reacted in the melter gasifier to partially combust the 
major portion of the petroleum coke to produce reduction gas which is 
directed to the reduction furnace. In the reduction furnace, the reduction 
gas reduces the metals forming metal vapors of zinc, cadmium and lead in 
the reduction top off gas and metallized iron from iron oxide in the waste 
dust material. The metallized iron is discharged hot to the melter 
gasifier for melting with petroleum coke and oxygen. The molten iron 
contains heavy metals freed from combustion of the petroleum coke. A slag 
is produced containing sulfur freed from combustion of the petroleum coke. 
The reduction top gas including the metal vapors contained therein are 
removed from the reduction furnace. Preferably the zinc, cadmium and lead 
metals from the metal vapors contained in the reduction gas are recovered 
and reused.

OBJECTS OF THE INVENTION 
It is a particular object of the present invention to provide a process for 
both disposing of two environmentally undesirable materials and providing 
a novel fuel and ferrous material feedstock for an iron making process 
which utilizes a melter gasifier. Other objects and advantages of the 
present invention will be apparent from the following detailed description 
read in view of the accompanying drawings which are made a part of this 
specification. 
DESCRIPTION OF THE PREFERRED EMBODIMENT 
The invention is predicated on the recognition that petroleum coke can 
advantageously replace coal or coke made from coal which heretofore was 
used as a source of carbon in iron making processes wherein a melter 
gasifier is used and that electric arc furnace dust can be effectively 
disposed of in such a process while providing a source of ferrous material 
for use in iron making. Further, in accordance with the invention zinc, 
cadmium or lead may be recovered as a byproduct. In addition, the use of 
petroleum coke in the iron making process in a melter gasifier 
substantially completely combusts the petroleum coke thus solving an 
environmentally sensitive disposal problem. Sulfur and heavy metals which 
are contained in petroleum coke are also safely disposed of in accordance 
with the invention. Further, electric arc dust which is classified as a 
hazardous waste because of the zinc, cadmium and lead components can be 
safely and economically disposed of in the process while providing a 
source of ferrous material for iron production. The sludge resulting from 
the process provides a concentrated source of zinc, cadmium and lead 
oxides from which the metals can be removed. The reduction furnace is 
operated at a top gas temperature of at least 400.degree. C., such that 
the metal vapors do not condense until entering the top gas scrubber. 
Along with entrained carbon and metallic iron dust the metal bearing 
sludge from the scrubber is dewatered and marketed to a recycling refiner. 
FIG. 1 is a flow diagram illustrating the method of refining crude oil and 
producing steel in an environmentally desirable manner wherein undesirable 
materials resulting in such production, namely petroleum coke and electric 
arc furnace dust, are disposed of in an iron making process. Petroleum 
feedstock 30 is introduced into a refinery 32 where oil and gas products 
34 are produced. The residual coke from the refinery 32 is passed to a 
delayed coker unit 36 where petroleum coke 38 is produced. Volatiles from 
the process are returned to the oil and gas products via conduit 39. The 
petroleum coke amounts to about 6% by weight of the petroleum feedstock 
being processed. 
Heretofore, disposal of the petroleum coke has been a significant problem. 
However, in accordance with the invention, disposal of the petroleum coke 
is accomplished in an advantageous manner as a fuel in an iron-making 
process where a melter gasifier is utilized. Thus, petroleum coke is 
introduced as a fuel into melter gasifier 40 for combustion with oxygen 
and metallic iron from source 42 which has been reduced from electric 
furnace dust in reduction furnace 44. Liquid iron containing heavy metals 
freed from the combustion of the petroleum coke is recovered in collection 
vessel 42 for later steel making 44. An reduction gas rich in CO is 
produced from the melter-gasifier and may be direct to the reduction 
furnace 44 and used in direct reduction of iron or as export gas 46 and 
used as a fuel for power production 48. Slag is withdrawn from the melter 
gasifier at slag collection vessel 50. The slag contains the sulfur freed 
from the combustion of the petroleum coke. Slag is disposed of; for 
example, by forming construction products 52. 
An electric arc furnace 31 is useful to produce steel products 35 from 
automotive scrap 33 which is the principal ferrous material used to charge 
electric arc furnaces. Automotive scrap contains a significant amount of 
zinc, cadmium and lead and this material is collected in the electric arc 
furnace dust as a waste material from the electric arc furnace steelmaking 
process. 
Thus, due to the use of "automotive scrap" feed, electric arc furnaces 
produce a waste product having high concentration of non-ferrous metals. 
Arc furnace "dust" includes zinc, cadmium and lead metals. The material 
has been designated a hazardous waste and is therefore increasingly a 
disposal problem for operators Present disposal costs range between about 
$150 and $200 per ton of "dust." Electric arc furnace dust typically 
contains 5% of zinc and can contain up to 20% of zinc depending on scrap 
quality. Residuals of cadmium and lead, up to 1%, are contained with the 
zinc contamination. 
The electric arc furnace dust from the furnace baghouse contains a 
significant amount of up to (95%) of a combination of iron oxide, lime and 
silica, in addition to the hazardous non-ferrous metals of concern. Iron 
oxide content is commonly about 50% by weight. The waste material may be 
agglomerated with lime and/or Portland cement, allowed to age to gain 
strenght and charged to a COREX.RTM. reduction furnace which is coupled to 
a melter-gasifier for producing molten iron. At the reduction temperature 
of around 850.degree. C., the volatile non-ferrous metals are vaporized 
and carried as top reduction gas to the off-gas scrubber 45 from the 
reduction furnace and captured in the sludge 47. 
Through the process of this invention, the quantity of arc furnace waste 
may be reduced to about 5% of the total dust volume now being disposed of 
in hazardous waste landfills. Moreover, due to a concentration of metals, 
recovery of metal value is possible from the gas scrubber sludge. The 
sludge will consist of approximately one-half non-ferrous metals and the 
other half of about equal parts of metallic iron and carbon dust. 
Electric arc furnace dust can be accumulated and agglomerated near an iron 
making site to be charged to the reduction furnace in "campaign" fashion 
during a pre-selected period of the iron making program with segregation 
of the non-ferrous metal sludge. Since the metals are vaporized and the 
gases present are reducing, the volatilized metal vapors will be 
transported through the pellet bed in the reduction furnace 44 as fume to 
the reduction furnace top gas duct which is heated to prevent metal 
condensation, and thereafter to the water based gas scrubber 45 for 
elimination as "campaign" scrubber sludge 47. 
The quantity of scrubber sludge may be segregated from "non-campaign" 
non-ferrous metal free scrubber sludge which is dried and directly 
recycled to the melter gasifier. The quantity of the non-ferrous metal 
"campaign" scrubber sludge is about one twentieth of the initial quantity 
of electric arc furnace waste charged to the COREX.RTM. process. Because 
non-ferrous metals may be present in the top gas duct work and condense on 
the metal lining, the metal duct work connecting the reduction furnace 44 
with scrubber 46 is preferably heated to at least or about 400.degree. C. 
during campaign operation. Due to the concentrated metals content of the 
scrubber sludge, it may be viable to further process the sludge to recover 
the metals content. 
In one form, the invention provides for "campaigning" the process of using 
electric arc furnace dust as the ferrous material feed for the COREX.RTM. 
process with the more conventional use of iron ore as the feed for the 
process. Thus, molten iron might be produced using petroleum coke and iron 
ore in a COREX.RTM. process for a given time period, for example three 
weeks to a month, then electric arc furnace dust, suitably agglomerated, 
is used to replace the iron ore as the feed to the reduction furnace in 
the COREX.RTM. process for a time period, for example a week, to process 
the electric arc furnace dust on hand. A scheduled of 11 consecutive 
months of using iron ore as the feed and 1 month of electric arc furnace 
dust is preferred. After this is accomplished, iron ore replaces the dust 
as the ferrous material in the process. The electric arc furnace dust is 
agglomerated into discrete particles about 1/2 inch in size, similar to 
iron ore pellets, using a bonding agent such as lime on Portland cement 
mixed with the dust for feed to a pelletizing apparatus. 
FIG. 2 schematically illustrates a melter gasifier useful with the present 
invention. The melter gasifier, generally indicated by the numeral 1 has 
side walls 2 which are refractory lined on their inner sides. The hood 3 
of the melter gasifier 1 has three openings 4, 5 and 6. In accordance with 
the opening 4 is adopted for charging petroleum coke 7 of various grain or 
piece sizes into the interior of the melter gasifier. Particulate ferrous 
material 8 preferably iron sponge from the reduction furnace, is charged 
into the melter gasifier through the opening 5. It is suitable to supply 
the iron sponge at an elevated temperature. In accordance with the present 
invention, the supply of sponge iron may be interrupted and electric arc 
furnace dust which has been reduced in the reduction furnace may be 
charged into the molter gasifier. To carry away the reduction gas which is 
formed during the reaction in the melter gasifier, a conduit 9 is provided 
extending out of opening 6. The reduction gas carried away may be is used 
in many processes to pre-reduce or reduce oxidic iron ore or electric arc 
furnace dust. It is advantageously used in the reduction furnace coupled 
to the melter gasifier. 
In general the melter gasifier comprises a lower section A, a central 
section B, an intermediate section C between sections A and B and an upper 
section D above the central section B, whose cross section is widened and 
which serves as an expansion zone. In the bottom region of the lower 
section A of the melter gasifier 1, which serves to collect molten metal 
and liquid slag including any sulfur residue from the combustion of 
petroleum coke, a tapping opening 10 for the melt 11 is provided in the 
wall 2. Further up the wall, there is an opening 12 for the slag tap in 
the lower section A. Alternatively, the slag may be tapped with the metal 
and separated outside the melter gasifier. In the lower region of the 
central section B of the melter gasifier 1, a nozzle pipe 14 is inserted 
through an opening 13 in the wall 2. Oxygen-containing carrier gas is 
injected into the melter gasifier through nozzle pipe 14. If desired, 
carbon carriers can be introduced into the melter gasifier 1 in a first 
horizontal blow-in plain 15. 
Preferably, a plurality of openings 13 with nozzle pipes 14 are present at 
this location spaced around the melter gasifier. In the central section B, 
a first fluidized bed zone 16 may be formed by coke particles from con, 
busted petroleum coke. The intermediate section C, which, in the 
embodiment illustrated, is cylindrically designed, is provided to 
accommodate a second zone 17 of a fluidized bed formed by coke particles 
from combustion the petroleum coke. Generally, the coke particles in the 
fluidized bed in this section of the melter gasifier will have less motion 
than those in section B. Through the wall of the intermediate section C, 
gas supply means, in the present case nozzle pipes or tuyeres 19, are 
inserted . The tuyeres are positioned to direct the gases toward the 
central axis 18 of the melter gasifier. The tuyeres are adapted for 
injecting oxygen-containing gas and carbon carriers into the melter 
gasifier. They project into the second zone 17 of coke particles, ending 
closely above the slag layer 20. Just one nozzle pipe 19 has been 
illustrated in FIG. 2 depending on the size of the melter gasifier, 10 to 
40 preferably 20 to 30, nozzle pipes 19 may be provided, and located 
substantially in a second horizontal blow-in plane 21. The nozzle pipes 19 
are arranged so as to be vertically pivotable in the direction of the 
double arrow 22. Also the nozzle pipes 14, through which the carrier gas 
and additional fuel flow into the first fluidized-bed zone 16 are designed 
to be vertically pivotable with the embodiment of the invention 
illustrated. 
The ferrous material 8 which as noted may be sponge iron or reduced 
electric arc furnace dust from the reduction furnace introduced through 
the opening 5 at first reaches the first fluidized-bed zone 16 after 
having fallen through the upper section D of the melter gasifier which 
serve as an expansion zone, in which the ferrous material is slowed and 
heated. The ferrous material may comprise iron ore or alternatively 
electric arc furnace dust in a batch type process. Smaller particles melt, 
drop through the second zone 17 of coke particles and descend into the 
lower section A. Larger particles at first remain lying on the second zone 
17 or are held fast in the uppermost layer of this zone, until they are 
also melted upon the action of the high temperature prevailing in the 
region of the first blow-in plane 15. In the second zone, the downwardly 
dropping metal melt is super-heated and, if desired, may be treated by the 
reaction of fine particle fluxes, which are introduced through the nozzle 
pipes 19. The metal melt 11 tapped through the opening in 10 is 
sufficiently hot in order to be subjected to further metallurgical 
aftertreatments. Above the melt 11, a layer of liquid slag 20 collects. 
The liquid slag may be stripped off via the tap opening 12. The petroleum 
coke particles, during operation of the melter gasifier, must be 
continuously supplemented through the opening 4 with larger pieces, which 
are preferably used to build up the second zone 17, after falling through 
the first zone 16. The melter gasifier shown in FIG. 2 and the prior art 
operation using coal or coke produced from coal are described in U.S. Pat. 
No. 4,588,437. 
Refer now to FIG. 3 which is a schematic flow sheet of the COREX.RTM. 
process in which the method of the invention is particularly useful. The 
COREX.RTM. process utilizes a melter gasifier substantially similar to the 
melter gasifier of FIG. 2 and is generally indicated in FIG. 3 by the 
numeral 100. The COREX.RTM. process is designed to operate under elevated 
gas pressures up to five bar. The process pressure is supplied from the 
integral oxygen production facility which supplies oxygen through the 
tuyeres 119 on the COREX.RTM. melter gasifier 100. Gasifier gas pressure 
from the melter gasifier 100 operates the primary direct reduction furnace 
126 for iron ore reduction to sponge iron when the process is being run 
with iron ore. Alternatively, electric arc dust may be reduced in the 
direct reduction furnace. 
Charging of petroleum coke to the melter gasifier 100 is accomplished 
through a pressurized lock hopper 128. The iron ore or electric arc 
furnace dust is supplied to the reduction furnace 126 through a similar 
lock hopper 121 in a manner well known to those skilled in the art. The 
petroleum coke is stored in a pressurized bin and charged into the melter 
gasifier by suitable means such as speed controlled feed screw 134. 
Upon entering the dome of the melter gasifier 100, at entry port 101, the 
10% of residual hydrocarbons contained in the petroleum coke are flashed 
off at 1100.degree. C. and cracked in the reducing atmosphere to CO and 
H.sub.2. The calcined petroleum coke particles are rapidly heated to 
1100.degree. C. and descend with the hot reduced iron particles and hot 
calcined lime particles from the reduction furnace 126 to the dynamic 
fluidized bed. The calcined petroleum coke (essentially all carbon) is 
gasified into CO which rises to the gasifier gas outlet 119. 
When electric arc furnace dust is utilized, with the high temperature 
reduction gas (850.degree. C.) and rich reducing conditions in the 
reduction furnace 126, the zinc, cadmium and lead from the electric arc 
furniture dust will be vaporized and be transported in the reduction 
furnace top off gases out exit 127. Since the non-ferrous metals are 
vaporized and the off gas stream is reducing, the metal vapors will be 
transported into the heated reduction furnace top gas duct work 137 to the 
top gas scrubber 129. The duct work 137 between the reduction furnace 126 
and the top gas scrubber 129 should be heated to at least 400.degree. C. 
to prevent condensation on the duct. With heated duct work, the 
non-ferrous metals will be transferred to the wet scrubber 129 and 
eliminated as sludge in vessel 141. Alternatively, with heated duct work 
and a liquid metal reservoir 143 ahead of the scrubber, the metal vapors 
can be condensed separately from the sludge and collected as a marketable 
metal product. 
The iron particles are melted in the dynamic particle bed 116 and drop to a 
molten liquid iron pool 111 accumulated below the oxygen tuyeres 119 on 
the melter gasifier hearth 114. The silica and alumina oxide content of 
the sponge iron is fluxed and melted with the calcined lime in the bed to 
form liquid slag droplets which descend and form a liquid slag layer 113 
covering the liquid iron pool 111. The liquid iron and slag are 
periodically tapped and removed through a taphole 110 from the melter 
gasifier hearth. 
As the calcined coke burns at a high temperature with oxygen above the 
tuyeres 119, an oxidizing coolant, such as steam or CO.sub.2, or both are 
injected at the tuyere level to maintain the melter gasifier dome 
temperature of 1100.degree. C. The injected coolants create additional 
reducing gas with hydrogen forming from reduction of the steam and CO 
forming from the reduction of the CO.sub.2. The combined reducing gases 
rise to the gasifier gas outlet main 119 at 1100.degree. C. where they are 
tempered with a side stream from the cooling gas scrubber 109 and cooling 
gas blower 140 via line 103 to 850.degree. C. before passing to the hot 
cyclone 115 and the reduction furnace 126. The gasifier gas cooling is 
useful to avoid fusion and maintain discrete free flowing particles in the 
column of the reduction shaft furnace 126. Overheating will cause clusters 
or clinkers to form inside the shaft furnace with disruption of the 
furnace solids and gas flow. 
After being cooled in the cooling gas scrubber 109 and cleaned of dust in 
the hot cyclone 115, the gasifier gas is passed upward in the reduction 
furnace 126 through the descending bed of ferrous material, either iron 
ore or agglomerated electric arc furnace dust, converting it to metallic 
sponge iron and carburizing the reduced iron to a level of three to five 
percent prior to hot discharge to the melter gasifier 100. The gasifier 
gases are partially consumed by the reaction in the reduction furnace and 
discharged at 127 as furnace top gas at 400.degree. C. The top gases are 
cleaned in the top gas wet scrubber 129, removing water vapor formed 
during iron ore reduction and discharged as export gas 131 at 40.degree. 
C. The export gas is low in particulates containing 25% of CO.sub.2. 
The highly preferred mode of the present invention utilizes petroleum coke 
in combination with a melter gasifier. The reduction gas from the melter 
gasifier is used in the reduction furnace to reduce the electric arc 
furnace dust to vaporize the non-ferrous metals, i.e., zinc, cadmium and 
lead, contained in the dust and to reduce the iron oxide contained in the 
dust. It is noted that coal or metalurgical coke could be used in place of 
petroleum coke as the fuel in the melter gasifier. Further the process of 
removing the non-ferrous metals could be carried out in a reduction 
furnace without need for a melter gasifier using a different source of hot 
reduction gas to vaporize the zinc, cadmium and lead. For example a 
suitable source of hot reduction gas would be the hot gas resulting from 
natural gas reforming. 
The present invention provides a method for processing environmentally 
undesirable materials including petroleum coke and the sulfur and heavy 
metals contained therein and waste dust from an electric arc furnace and 
the cadmium, lead, zinc and iron oxide contained therein and of providing 
fuel and a charging material for a process of making molten iron or steel 
preproducts and reduction gas in a melter gasifier. A melter gasifier is 
provided and has an upper fuel charging end, a reduction gas discharging 
end, a lower molten metal and slag collection end. A reduction furnace is 
operably connected to the melter gasifiers. An entry is formed for 
charging metallized ferrous material into said melter gasifier from a 
reduction furnace. Petroleum coke is introduced into the melter gasifier 
at the upper fuel charging end and oxygen-containing gas is blown into the 
petroleum coke to form at least a first fluidized bed of coke particles 
from the petroleum coke. Vaporized zinc, cadmium and lead from the 
electric arc furnace waste dust material which has been processed in the 
reduction furnace is removed with the top off gas. Metallized iron oxides 
are introduced into the melter gasifier through the material changing 
entry means. The petroleum coke, oxygen and metallized iron oxides from 
waste dust material are reacted to combust the major portion of the 
petroleum coke to produce reduction gas and molten iron. The molten iron 
contains the heavy metals freed from combustion of the petroleum coke. A 
slag is formed containing sulfur freed from combustion of the petroleum 
coke. The reduction gas is removed from the melter gasifier and use in the 
reduction furnace. 
The principles, preferred embodiments and modes of operation of the present 
invention have been described in the foregoing specification. However, the 
invention which is intended to be protected is not to be construed as 
limited to the particular embodiments disclosed. The embodiments are to be 
construed as illustrative rather than restrictive. Variations and changes 
may be made by others without departing from the spirit of the present 
invention. Accordingly, all such variations and changes which fall within 
the spirit and scope of the present invention as defined in the following 
claims are expressly intended to be embraced thereby.