Patent Publication Number: US-2015061200-A1

Title: Apparatus for making liquid iron and steel

Description:
INTRODUCTION 
     The present invention relates to the making of iron and steel and is an improvement over Applicant&#39;s U.S. Pat. No. 6,409,790 B1, issued on Jun. 25, 2002, hereinafter referred to as the “referenced patent.” 
     This referenced patent discloses a method and apparatus for practicing carbonaceous-based metallurgy, and in the specific case of making liquid iron, two distinct steps are involved. The first step comprises the formation of an iron/carbon product in a horizontal tubular reactor wherein a gas containing oxygen is injected from a horizontal lance inserted from the discharge end of the horizontal reactor while the hot iron/carbon product (intermediate) formed is discharged into a vertical reactor. The second step comprises the melting of the iron/carbon product in the vertical reactor, called a “melter/homogenizer,” by means of the injection of a gas containing oxygen using a vertical lance to convert iron/carbon product into liquid iron which is fed into a holding reservoir. Specifically, the instant invention relates to improvements made to the referenced patent as it relates to the making of liquid iron comparable to liquid iron produced in a blast furnace, which is commonly known in the steel industry as “Hot Metal.” 
    
    
     BACKGROUND 
     The steel industry in March 1998 issued a comprehensive publication entitled “Steel Industry Technology Roadmap,” and on page 11, it states the following: 
     The ultimate objective in the iron smelting area is to develop a coal-based process that produces liquid iron directly from coal and ore fines or concentrate. Liquid iron is preferred to solid iron because there is no gangue and it retains its sensible heat. Coal is obviously preferred over coke or natural gas because of its abundance and lower cost. If possible, the use of fines or concentrate will eliminate agglomeration costs. These new processes should have a high smelting intensity or productivity. High productivity and the elimination of cokemaking and agglomeration will significantly reduce capital costs. 
     In substance, the Roadmap&#39;s ultimate objective was, and still is, to substitute several plants, shown within the blue enclosure of Exhibit 1, with one single efficient plant. The Applicant conceived the subject matter disclosed in the reference patent as a solution to the ultimate objective of producing liquid iron directly wherein coal and ore fines or concentrate are used; a patent application was filed, and the reference patent was issued. 
     To put the concept into practice, a pilot was constructed (Exhibit 2) and tests were initiated. A multitude of problems were discovered. The most serious problems consisted of the following: 
     No 1. Sporadic explosions caused by super-heated steam generated from water leakage from the melt-down of the stainless steel outer tube (sheath) at the copper tip of the water-cooled, oxygen injection lance (Exhibit 3), which endangered operating personnel, one of whom experienced severe bums, necessitating a hospital stay. To prevent the melting of the stainless sheath, steps were taken to increase the size of the copper tip. Unfortunately, excessive build-up at the tip of the lance occurred (Exhibit 4), resulting in destroying the flow pattern of the oxygen. 
     No 2. The uniform flow of the gas containing oxygen from the tip of the lance is most critical in order to produce a uniform product, an iron/carbon intermediate of some 50% metallization with about 6% carbon is suitable for conversion into carbon-saturated liquid iron of blast furnace specification. The problems caused by the build-up at the tip of the lance included premature melting, over-oxidation, too low in metallization, and completely unreduced feed material. 
     No 3. Excessive heat loss occurred within the horizontal reactor, especially toward its discharge end, caused by the cooling effect from the water-cooled lance. 
     No 4. Build-up at the discharge end of the horizontal reactor itself persisted (Exhibit 5), resulting in a physical blockage that prevented the advancement of the contents of the horizontal reactor by means of the pushing ram of the charger, thus forcing unscheduled shutdowns. 
     No 5. Build-up downstream of the horizontal metalizing reactor and upstream of the storage was also experienced in the vertical section where the homogenizer/melter would be located, causing shutdowns that entailed moving equipment to provide access to poke hot, built-up material with a bar to unplug the build-up; Exhibit 6. 
     No 6. Iron/carbon intermediate that was fed to the melting furnace, being lighter than the liquid iron, would float on top of the molten bath (Exhibit 7) and dwell there, instead of entering into solution with the metal in the molten bath, such flotation of intermediate preventing the rapid and complete conversion of the intermediate into liquid iron. 
     In addressing problems No 1, No 2, and No 3, it was decided to relocate the injection lance to be introduced from the cold end through the charger of the horizontal metallizing reactor, as shown in Exhibit 8, together with increasing the pressure of injection of the gas containing the oxygen to create a forceful jet from the tip of the lance to reach all the way to the discharge end of the horizontal metalizing reactor, with the tip of the lance being located where the temperature of the iron ore and ash are below their incipient fusion. This required the construction of a new charger (Exhibit 9), wherein a provision was made for the lance to pass through the center of the mandrel, resulting in a structure of the lance being disposed through the mandrel and the mandrel through the pushing ram. 
     In addressing problem No 4, which relates to the blockage created by build-up at the discharge end of the metallizing reactor, the new charger was constructed structurally more robust than the initial one, and also the hydraulic pressure was raised by adding a booster hydraulic pump with new controls (Exhibits 10A and 10B) to increase the pushing force of the new charger in order to surmount blockage. 
     In addressing problem No 5, to prevent build-up downstream of the metalizing reactor and. upstream of the storage, it was decided to completely eliminate the homogenizer/melter (numeral 11), described in the referenced patent, and perform the melting of the iron/carbon intermediate in an induction channel furnace (ICE) as that made by Ajax Magnethermic, with certain modifications as would be described in detail hereinafter, to serve both as a melter as well as storage of liquid iron. 
     In addressing the issue of the intermediate flotation on top of the molten bath, a vertically oscillating mechanical dunker was developed (Exhibit 11A) which was equipped with a graphitic block (Exhibit 11B) which is adapted to force the floating intermediate to be submerged below the level of the high-temperature bath where the carbon in the intermediate completes the reduction of the unreacted oxides of iron, namely, Fe 2 O 3 , Fe 3 O 4 , and FeO, which have not reacted in the horizontal metallizing reactor. 
     With the changes made, the Applicant was successful in overcoming the problems mentioned hereinbefore and producing an acceptable intermediate into which carbon from the coal is integrally imbedded within the metallized iron made from ore fines or concentrate in the horizontal metalizing reactor (Exhibit 12). 
     Further, two valuable gases are co-produced: one during the metallization of the iron ore in the horizontal metallizing reactor and a second during the melting of the intermediate (Exhibit 13). 
     To summarize the above, the Applicant, in effect, has invented an apparatus adapted to accept various proportions of ore and coal and yet produce a liquid iron (Exhibit 13) by way of producing an intermediate whose composition is quite suitable to be converted to liquid iron that can be subsequently converted into low-cost steel. 
     OBJECTIVE OF THE INVENTION 
     The main object of this invention is to produce liquid iron directly from ore fines and concentrate using low-cost coal consistent with the Ultimate Objective stated in the  Steel Industry Technology Roadmap  of March 1998, mentioned above. 
     Another object of the present invention is to provide an efficient apparatus to carry out same for converting an iron ore and coal mix into liquid iron at an efficiency greater than the conventional process of making liquid iron in a blast furnace that uses coke and iron ore pellets. 
     Therefore another object of the instant invention is to provide an apparatus that greatly reduces heat loss when compared with the conventional process of making liquid iron in a blast furnace that uses coke and iron ore pellets. 
     Still another object of the instant invention is to provide an apparatus that greatly reduces emissions when compared to conventional processes that feed pellets, sinter, and coke into a blast furnace, which in turn is a major emitter of carbon dioxide (CO 2 ). 
     Further another object of the present invention is making an induction channel furnace (ICF) more efficient while still protecting its lining by providing dunking means which assist in submerging an iron/carbon intermediate into the molten iron bath in the ICF in order to expedite its reaction and cause it to blend with the constituents in the molten iron bath to result in its rapid liquifaction and assimilation within the molten iron bath. 
     Further still another object of the present invention is to physically integrate an induction channel furnace (ICF) to a steelmaking furnace, such as to a basic oxygen steelmaking furnace or to an electric arc steelmaking furnace, known in the industry as BOF and EAF, respectively, but by way of example, the description that follows will disclose the integration of the ICF to the BOF, the ICF being adapted to convert an iron and carbon intermediate into molten iron while the BOF converts molten iron and scrap into steel. The ICF and the BOF are joined together structurally in such a way as to result in a hybrid, dual-purpose configuration that reduces capital and operating costs, increases efficiency, and minimizes emissions. 
     Further yet another object of the present invention consists in providing a physical interconnection between the ICF and the BOF to enable the direct pouring of molten iron directly from said ICF in said BOF by revolving both said ICF and said BOF radially without necessitating the use of a crane. 
     It is still another object of the present invention to provide a novel apparatus per se in the case of making molten iron only in situations where iron making is required without the production of steel. 
     It is therefore another object of the present invention to provide an apparatus that can convert carbon dioxide (CO 2 ), a greenhouse gas, into a useful product such as fertilizer. 
     Other objects of this invention will appear from the following description and appended claims. Reference is made to the accompanying drawings which describe certain apparatus structures to practice the making of an iron/carbon intermediate which is converted to liquid iron, that is subsequently converted into steel. It is to be understood that the apparatus disclosed herein are not limited solely to the processing of iron-bearing ore, as the invention can also be applied to other non-iron bearing ores. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates the plant to directly make liquid iron from coal and ore fines or concentrate. 
         FIG. 2  represents the metallizing reactor in perspective and in section, and  FIG. 2A  shows the actual iron/carbon intermediate with the carbon being physically imbedded in the metallized iron. 
         FIG. 3  illustrates in perspective a battery of metallizing reactors that produce the intermediate. 
         FIG. 4  is a close-up and partial view of the induction melting furnaces with the intermediate delivery system. 
         FIG. 5  illustrates a side elevation of the plant, which includes gas cleanup and the co-production of fertilizer (oxamide) from a gas containing CO 2 . 
         FIG. 6  illustrates the integration of a steelmaking furnace, which is commonly known as a basic oxygen furnace (BOF), to an ironmaking furnace, which is commonly known as an induction channel furnace (ICF). 
         FIG. 7  through  FIG. 18  show the various operating steps of producing the liquid iron and its conversion into steel, which are simultaneously carried out with the iron liquid produced in the ICF and the steel in the BOF. 
     
    
    
     Before describing in detail the present invention, it is to be understood that this invention is not limited to the details or arrangement of the parts illustrated in the attached drawings, as the invention can be operative by using other embodiments. Also, it is to be understood that the terminology herein contained is for the purpose of description and not limitation. 
     DETAILED DESCRIPTION OF THE DRAWINGS 
       FIG. 1  illustrates conceptually a plant consisting of two batteries, marked  20 ( a ) and  20 ( b ), with each comprising several identical metalizing reactors, one of which is marked by numeral  21 , two melting furnaces marked A and B, and conveyors that feed hot iron/carbon intermediate made in the metalizing reactors to the two melting furnaces. 
     In describing the plant in more detail, the Applicant will describe only battery  20 ( a ) and furnace A, since the two batteries and the two furnaces are identical. 
     Beneath each battery, two conveyors, marked by numerals  22 ( a ) and  23 ( a ), are disposed, with conveyor  22 ( a ) being fixed, and conveyor  23 ( a ) is adapted to travel as a shuttle conveyor. Shuttle conveyor  23 ( a ) is adapted to travel not only to furnace A, but also all the way to the end of furnace B, in order to provide redundancy. Furnace A possesses three identical feed openings, marked by numeral  24 , equally spaced along the length of both furnaces to enable shuttle conveyor  23 ( a ) to distribute hot iron/carbon intermediate along the length of furnace A as well as furnace B. At the head of shuttle conveyor  23 ( a ), a dunker, marked by numeral  25 , is disposed to immerse into the molten bath, iron/carbon intermediate that is fed into furnace A or furnace B. It is to be noted that shuttle conveyor  23 ( b ) can service both furnace A and furnace B. 
     Referring to  FIG. 2 , it illustrates iron/carbon metallizer reactor  21  in perspective and in section, with feed-hopper  26  adapted to feed coal and feed-hopper  27  to feed a mix of ore and coal. Numeral  28  represents the charger, which is made-up of mandrel  29  and main ram (pusher)  30 , with lance  31  being disposed through the center of mandrel  29  with penetration at the charging end of reactor  21 . The coal core is the dark colored material denoted by numeral  32  through which lance  31  passes and annulus  33 , which is made-up of an iron-and-coal mix, fully surrounds coal core  32 . The discharge of reactor  21 , which consists of a hot radiant chamber, is marked by numeral  34 ; it possesses an inlet port  35  for mounting a start-up burner. A slide gate provided downstream discharge chamber  34 , marked by numeral  35 ( a ), serves as a control feeding apparatus to service a surge containment vessel from metalizing reactor  21  into main conveyor  22 ( a ) (shown in  FIG. 1 ) at a predetermined sequence, since conveyor  22 ( a ) receives iron/carbon intermediate from several metalizing reactors. It is to be noted that metalizing reactor  21  is lined with insulation and refractory material with heating flues built in the refractories to radiate heat into reactor  21  in order to provide thermal energy to heat annulus  33  bi-directionally. The heating flues are not shown, as it is commonly used in industry, and they are always encased in a steel shell marked by numeral  39 .  FIG. 2A  represents the actual structure of the iron/carbon intermediate which clearly shows carbon which originated from coal, interspersed in iron which originated from the ore. Such intermediate is the feedstock to produce liquid iron by way of melting it. During metallization of the iron ore with coal, a hydrogen (H 2 ) rich gas is generated; this gas, which is quite valuable as an energy source, leaves through exit port  37 . 
     Referring to  FIG. 3 , it illustrates battery  20 ( a ) with most of its components described in  FIG. 1  and  FIG. 2 , except for numeral  40  which represents the distribution conveyors of feed into feed-hoppers  26  and  27 . The other equipment is represented as follows: The skip hoist to deliver feed from ground level by numeral  41 , the furnace exhaust suction duct by numeral  42 , the exhauster by numeral  43 , flue gas injection manifold by numeral  44 , and sizing screen by numeral  45  which separates the screenings from the iron/.carbon intermediate prior to being fed into furnace A to minimize dust emissions during the feed of the intermediate. 
     Referring to  FIG. 4 , it illustrates part of battery  20 ( a ), induction channel furnace A, and part of furnace B. In addition to what was described in previous Figures, furnace A is shown with a front part missing to illustrate the internals of the furnace with a graphite immersion block marked by numeral  46  at the left side of furnace A. Other parts include the upper component of dunker  25  that forces the iron/carbon intermediate floating on top of molten iron which is immersed into molten bath  72 , swivel joint  47  which permits the rotation of the furnace while still continuously extracting combustion gases from within furnace A, the furnace hearth  48 , and the combustion of CO above the hearth being released from the reaction of oxygen from the iron oxides with carbon contained in the immersed iron/carbon intermediate. 
     Referring to  FIG. 5 , it represents a side elevation of the plant wherein conveyor  22 ( a ) and conveyor  23 ( a ) have been replaced by a stand pipe marked by numeral  49  followed by valves  50  and  51  controlling the feed of iron/carbon intermediate directly into induction channel furnace A and exhausting the flue gas (N 2 +CO 2 ) from furnace A to the bottom of stand pipe  49 . A piping system denoted by numeral  52  connects to heat exchanger  53  which feeds relatively cold gas containing mercury into cleanup bed  54 ( a ) or cleanup bed  54 ( b ); these two beds, which alternate in usage, contain activated carbon to extract mercury from the gas. Downstream from exchanger  53 , a desulfurizer  55  forms the lower part of a hot-gas cleanup with a sorbent regenerator  56  disposed above desulfurizer  55 . Two reactors  59 ( a ) and  59 ( b ) are disposed downstream of desulfurizer  55  to serve as converters of carbon monoxide (CO) to cyanogen, and downstream of sorbent regenerator a sulfur recovery system marked by numeral  57 ; it serves to recover the sulfur in elemental form, a marketable commodity. A second heat exchanger denoted by numeral  58  conditions the desulfurized gas. Reactors  59 ( a ) and  59 ( b ) alternate from being a producer of cyanogen to a regenerator of the catalyst. Downstream of reactors  59 ( a ) and  59 ( b ) a liquifier marked by numeral  60  is provided; it is followed by separator  61 , and pump  62  which elevates the cyanogen to be hydrated in column  63  to form oxamide, a slow-release fertilizer. A settling tank  64  is disposed upstream of filter press  65  while drier  66  follows filter press  65 , and stacker  67  transports the final product as a marketable fertilizer to storage  68 . 
       FIG. 6  illustrates the integrating of steelmaking to ironmaking by means of a BOF to an ICF, both referenced in the Objective section in this disclosure; it is feasible to consolidate the following three steps in a single, low-cost, efficient, physically integrated apparatus adapted for:
         Metallization of iron ore consisting of fines or concentrate with coal forming an intermediate;   Melting the intermediate producing liquid iron; and   Blowing the liquid iron with oxygen producing steel.       

     Since such apparatus for metallization and melting has been described in detail above,  FIGS. 7 to 18  will describe the apparatus for feeding the iron/carbon intermediate, melting it into liquid iron and producing the steel. 
       FIG. 7  illustrates shuttle conveyor  23 ( a ) or conveyor  23 ( b ) feeding iron/carbon intermediate into the ICF with material floating on the molten bath marked by numeral  71  while oxygen is being blown within the BOF by means of a vertical lance  69  converting the iron into steel with fumes being collected in hood  70 ; a hoist marked by numeral  73  serves to raise and lower lance  69 . 
       FIG. 8  is the same as  FIG. 7 , except for dunker  25  positioning graphitic block  46  over the intermediate which is still floating over the molten bath.  FIG. 9  shows that graphitic block  46  has immersed the floating intermediate into bath  72 . 
       FIG. 10  illustrates the pouring of the slag from the BOF into pot  75  while using a stopper rod denoted by numeral  74  to prevent the flow of liquid iron from the ICF by virtue of the ICF being in a tilted position.  FIG. 11  illustrates tapping of the steel from the bottom of the BOF into ladle  76  using slide gate  77 . It is to be noted that the slagging and tapping of the BOF may be effected by other configurations. 
       FIG. 12  illustrates the heat in the BOF has been tapped and the dropping of a tapping-hole sealing material  78  into the BOF tap hole marked by numeral  79 .  FIG. 13  illustrates sealing material  78  in the process of filling tap hole  79 , and  FIG. 14  shows the tap hole  79  to have been sealed. 
       FIG. 15  illustrates the slagging of the ICF by tilting the ICF counter-clockwise, with slag produced from melting the intermediate marked by numeral  80 , being poured out from the ICF.  FIG. 16  illustrates the tilting of the ICF clockwise to enable the charging of the BOF with scrap, which is marked by numeral  81 , by means of chute  82  with stopper rod  74  being in the down position to prevent molten iron from flowing from the ICF into the BOF during the charging of the scrap.  FIG. 17  shows that while the ICF and the BOF are in the tilted position, stopper rod  74  is in the raised position allowing the liquid iron, marked by numeral  83 , to flow from the ICF into the BOF, dispensing a predetermined charge of liquid iron on top of scrap  81 . At this point the ICF is rotated from its tilted position to the erect position, hood  70  rotated over the mouth of the BOF, oxygen lance  73  hoist lowered into the BOF to begin converting the liquid iron into steel by blowing oxygen from lance  69  while conveyor  23 ( a ) or ( b ) positioned over charging hole  24  of the ICF, proceeds the feeding of iron/carbon intermediate into the ICF to melt it while the liquid iron and the scrap are being converted into steel, as illustrated in  FIG. 18  which is the same as  FIG. 7 , which illustrates the same functions of feeding iron/carbon intermediate by conveyor  23 ( a ) or ( b ), melting it into liquid iron in the ICF to form bath  72  and converting the liquid iron and scrap into steel, while iron ore fines or concentrate undergo metallization with coal in metalizing reactor  21 , shown and described in  FIGS. 1 through 5 , inclusive. 
     With respect to the application of this invention to the non-ferrous metals, variations to that which is disclosed herein, can take place; however, the intention is not to depart from the spirit of this disclosure. All in all, it is submitted herein that the instant invention provides major improvement over conventional practice/metallurgy, which can use low-cost raw materials, and which is energy efficient and environmentally friendly, while requiring low capital investment.