Patent Publication Number: US-2019169703-A1

Title: Glass-making-quality granulated slag process

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This disclosure is a continuation-in-part application of U.S. patent application Ser. No. 15/146,703 filed on May 4, 2016 which claims the benefit of U.S. Provisional Application No. 62/156,607 filed on May 4, 2015, both of which are hereby incorporated by reference. 
    
    
     TECHNICAL FIELD 
     This disclosure is related to a process for creating glass-making-quality granulated slag, an additive for the making of glass into flat sheets and containers. 
     BACKGROUND 
     The statements in this section merely provide background information related to the present disclosure. Accordingly, such statements are not intended to constitute an admission of prior art. 
     Slag is a by-product of the creation of iron and other metals from ore. Slag is a mixture of stony products, metal fragments including iron and alumina, silica, and other materials. One common use of ground granulated blast furnace slag is the production of blended cements, using properties of the slag to improve upon the properties of common Portland cement. 
     Another, less-utilized use for slag is the production of glass products. However, glass products using slag as an ingredient are sensitive to alumina and silica contaminants. Glass made with contaminated slag can cause pocks, voids, and other weaknesses. Further, slag particle size can affect the quality and ease of manufacture of glass products. Particles that are too large can weaken the glass. Particles that are too small or are essentially slag dust are very difficult and/or hazardous to deal with as they tend to create a cloud of particles in the air upon delivery and handling at the glass maker&#39;s facility. 
     Methods to create slag particles in particular size range include taking an already cooled slag and crushing the slag. 
     SUMMARY 
     A process for forming granulated slag includes collecting a molten slag flow directly from a blast furnace in a temperature range between 2500° F. and 2600° F., quenching the molten slag flow with a flowing spray of water while the molten slag flow is still in the temperature range between 2500° F. and 2600° F. to create a granulated slag flow such that ferrous materials and non-ferrous metallic materials solidify joined together in the granulated slag flow, drying the granulated slag flow, magnetically separating the solidified joined ferrous materials and non-ferrous metallic materials from the granulated slag with a magnet device, and size-screening the granulated slag flow. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       One or more embodiments will now be described, by way of example, with reference to the accompanying drawings, in which: 
         FIG. 1  illustrates a process flow chart for an exemplary process to create glass-making-quality granulated slag, in accordance with the present disclosure; 
         FIG. 2  illustrates a process flow chart for an alternative exemplary process to create glass-making-quality granulated slag, in accordance with the present disclosure; 
         FIG. 3  illustrates exemplary machinery accomplishing quenching steps of the disclosed process, in accordance with the present disclosure; 
         FIG. 4  illustrates exemplary machinery accomplishing plant operation steps of the disclosed process, in accordance with the present disclosure; 
         FIG. 5  illustrates an exemplary rotary drum magnet device, in accordance with the present disclosure; 
         FIG. 6  illustrates an exemplary quenching station including a cooling box, in accordance with the present disclosure; and 
         FIG. 7  illustrates photographically an alternative exemplary embodiment of a quenching station, viewed from within a trough of the quenching station, in accordance with the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     A unique process has been developed to utilize a special type of blast furnace slag called glass-making-quality granulated slag coming from an exemplary iron making facility. For the purposes of this disclosure, an embodiment of the glass-making-quality granulated slag can be labeled or described by the product name Vitrafine™. This glass-making-quality granulated slag has most of the metal and alumina contaminants removed and has been selected/sorted for particles in a conforming contaminant range. 
     An exemplary process for creating conforming glass-making-quality granulated slag from a flow of untreated slag. In a first step of the exemplary process, the process begins with collecting the slag and determining slag chemistry appropriate for production of the desired glass-making-quality granulated slag. 
     An exemplary sub-set of steps to collect and certify molten slag from a blast furnace creating iron is provided. The molten slag is tapped from a notched hole in the bottom of the furnace and begins to flow down a ceramic trough in a liquid state of approximately 2500 degrees Fahrenheit which is verified by the operator. The trough is made up of various hard, heat and wear-resistant materials cast in a U-shape and sloped to promote gravity flow. Attention to the chemical and physical properties as well as when replacement and repair of these runners take place is critical. At repair and replacement time the hardened minerals loosen from the runner and increase in the slag product contaminating it when it is water quenched. The chemistry of the slag must be examined to determine whether the slag is a conforming unprocessed slag capable of being utilized for glass-making-quality granulated slag. If large concentrations of contaminants are determined to be present, whether from the iron making process or from the runner, the product is determined to be non-conforming slag and aborted for other purposes. 
     In a next step of the exemplary process, beginning a sub-set of process steps which can be labeled the quenching steps, the slag must be provided from the smelting process in a temperature range of between 2,500° F.-2600° F. 
     Once the molten blast furnace slag reaches the cooling box sprays, which provide ten (10) times the water volume to slag, it causes the slag to expand and crystallize into what is called granulated slag. The liquid slag is water-quenched instantly into a solid state. Adequate water flow and substantially cold water ideally in the range of 150° F.-170° F. is important to generate adequate generation of slag particles in the desired size and shape range. The coolant water needs to be below 200° F. to be effective. Knowledge of the slag temperature and replacement water volume is critical to the cooling water temperature. Low temperatures do not produce the proper product for further processing at the plant and will have to be aborted. 
     Attention is required of the cooling water temperature so as to have a consistent quenching of the slag for further processing in the plant. The amount of water circulation change needs to be monitored from that which is relieved as steam and that which is evacuated to the water treatment facility and returned as cooled replacement water. 
     The granulated slag, wet from the quenching process, goes through a rotating drum to be dewatered and then is transported to a dewatering silo. In an optional stage, the quenched slag mixed with water can be filtered or screen separated, removing undersized particles from the slag mixture while the slag particles are still mixed with the quenching water. In this way, many fine particles are removed with the water going to the water treatment facility which removes many contaminated fines that do not meet the separation criteria. 
     In a next step of the exemplary process, a quality check can be performed upon the quenched slag from the previous step. Visual acceptance is first utilized as discolored material is the sign of an inferior product. In one embodiment, samples of the granulated slag are taken and reviewed by a laboratory to determine a number of contaminants in the sample. If the slag meets the noted criteria it is considered acceptable for plant processing and the quenching steps can be considered complete. Upon determination of required quality parameters of the slag from the blast furnace granulation process, the slag is labeled as premium granulated slag, stockpiled, and ready for processing in the Vitrafine™ plant. 
     In a next step of the exemplary process, the stockpiled premium granulated slag dewaters further in the stockpile for several days before being loaded by an exemplary end-loader to a plant reservoir called a bin. 
     In a next step of the exemplary process, beginning a sub-set of process steps which can be labeled as plant operation steps, a first plant operation step is screening to remove grossly oversized particles then introduction into an exemplary natural gas rotary drum dryer to remove moisture. This dried slag flow can optionally be screened at this point, for example, with a particle screen, for further particle distribution. 
     In treating slag flows that include an iron contaminant content, optional plant operation steps can be initiated to remove the iron contaminants. In one exemplary step to achieve separation of iron particles from the slag flow, one or more rare earth rotary drum magnets are in the flow. Magnetic particles are strongly attracted to the drum surface and removed from the slag flow. The iron particles once beyond the magnetic field of the drum magnet are then separated from the drum for further processing. 
     The drum magnets are designed to efficiently separate iron particles by placement of the magnetic rare earth magnets within the drum. The magnetic material utilized inside the drums are a specially made magnet that can withstand high heat without losing the magnet properties. 
     While alumina and other non-ferrous particles are not attracted to the magnetic drums, testing has found that the iron particles removed by the drums tend to also include other contaminants. By separating out the ferrous particles, the other contaminants are largely removed as well. 
     A next plant operation step includes transferring the dried slag material to a separating device or devices configured to separate conforming slag particles of the desired size and shape from non-conforming particles. In one exemplary configuration to accomplish this separation, a bucket elevator takes the slag to a splitter tube that distributes the material over two exemplary Midwest 4 deck vibratory screens with rubber balls for increased screening capacity that separate specifically sized gradation material into a finished product that is 24 mesh by 140 mesh. Oversized and undersized materials are separated from conforming material, which can then be transported or removed pneumatically to a storage silo for shipping. Material not meeting the specific size can be separated into larger than 24 mesh and smaller than 140 mesh for reprocessing or marketing into other products. In one optional embodiment of the process, the rejected slag material labeled as larger than 24 mesh flows into a crusher device for further size reduction and recirculates back to the screens for separation repeating the separation step of the process. In one exemplary configuration, the crusher device has the capability of changing the rotation speed through a variable speed setting on the motor to minimize crushing the granulated slag to a size smaller than that which is required conforming slag. 
     In one exemplary process step, the smaller than 140 mesh material is pneumatically delivered to a silo for sales to alternate non-glass manufacturing facilities. 
     After the separation step, the plant operation steps end and the conforming slag flow from the separation process can be labeled as Vitrafine™ or glass-making-quality granulated slag. Additional testing can be performed to sub-classify the Vitrafine™ or confirm presence of contaminants that would cause a problem in the glassmaking process. 
       FIG. 1  illustrates a process flow chart for an exemplary process to create glass-making-quality granulated slag. Process  10  starts at step  12 . At step  14 , a molten flow of slag is collected. At step  16 , the molten flow of slag is quenched rapidly to create a flow of granulated slag. At step  18 , the granulated slag is dried. At step  20 , the granulated slag is size-screened or separated according to size, providing a flow of conforming size slag particles. At step  22 , process  10  ends. 
       FIG. 2  illustrates a process flow chart for an alternative exemplary process to create glass-making-quality granulated slag. Process  50  starts at step  52 . At step  54 , a molten flow of slag is collected. At step  56 , the molten flow of slag is quenched rapidly to create a flow of granulated slag. At step  58 , the granulated slag is dried. At step  60 , a magnetic device separates ferrous material from the granulated slag. At step  62 , the granulated slag is size-screened or separated according to size, providing a flow of conforming size slag particles. At step  64 , slag that was rejected at step  64  for being oversized is crushed and recycled to the size-screening process. At step  66 , process  50  ends. 
       FIG. 3  illustrates exemplary machinery accomplishing quenching steps of the disclosed process. Quenching operation  100  is illustrated. Molten slag flow  102  is delivered to quenching station  110 , wherein coolant water flow  104  is provided to very quickly cool the slag and created granulated slag according to the disclosure. Quenched slag flow  112  leaves station  110  and is transported to drying station  120 . Post-quench coolant water flow  114  includes very fine slag particles that are picked up in the water during the quenching process. Flow  114  leaves station  110  and is delivered to filtering station  140  which provides filtered small slag particle stockpile  144  and filtered coolant water flow  142  to be conditioned and resupplied as flow  104 . Drying station  120  receives quenched slag flow  112  and uses mechanisms such as a spinning dewatering drum, configured to, for example, remove water and heat the quenched slag, to separate water from the quenched slag and begin to dry the premium granulated slag flow. Premium granulated slag flow  122  leaves station  120  to be stockpiled at bin station  130 , wherein the premium granulated slag is permitted to continue to dry in preparation for being loaded as flow  132  into transportation to an exemplary separate plant operation at a different physical location. In other embodiments, the plant operation can be in the same physical site as the quenching operation. 
       FIG. 4  illustrates exemplary machinery accomplishing plant operation steps of the disclosed process. Plant operation  200  is illustrated. Premium slag stockpiles  205  are illustrated including slag that was delivered from a quenching operation and is continuing to dry. Premium slag flow  202  is created by providing premium slag from stockpiles  205 . Drying station  210  receives premium slag flow  202  and uses mechanisms such as a spinning drum and heat, such as can be supplied by using a natural gas burner or burners or similar devices, to complete drying the premium slag flow. Dried slag flow  212  leaves station  210  and is delivered to grossly oversized particle separation station  220  which separates out large particles from the dried slag flow and creates grossly oversized particle stockpile  224 . In one exemplary embodiment, station  220  separates particles with a diameter greater than ⅜ inch from the slag flow. In one alternative embodiment, stations  220  and  210  can be reversed, with the grossly oversized particles being removed from the slag flow prior to drying, in order to avoid spending energy drying clearly rejected components of the slag flow. Slag flow  222  leaves station  220  and is delivered to magnetic drum station  230 . Magnetic drum devices, in one exemplary embodiment, four rotary drum rare earth magnet devices, are put in station  230  within the slag flow to attract and remove from the flow ferrous particles that are attracted to the magnets. Station  230  provides ferrous particle stockpile  234 . Slag flow  232  leaves station  230  and is delivered to large particle separation station  240 , where mesh screens are used to separate particles that are larger than a desired glass-making-quality slag particle size range specification. Station  240  provides oversize slag particle stockpile  244 . Slag flow  242  leaves station  240  and is delivered to small particle separation station  250 . Mesh screens are used in station  250  to separate particles that are smaller than the desired glass-making-quality slag particle size range specification. Station  250  provides undersize slag particle stockpile  254 . Conforming glass-making-quality slag flow  252  leaves station  250  to create glass-making-quality slag stockpile  256 . 
     The stations of  FIGS. 3 and 4  are exemplary. Many of the operations can be swapped in location with other operations or combined into mixed or multiple function stations in accordance with the disclosure. Stations can be eliminated, for example, with the grossly oversized particles and the oversize slag particles being separated from the premium slag flow at a single station or with a single screen in accordance with the disclosure. 
     The disclosed process provides 24 mesh and 140 mesh screens as useful for size-screening conforming slag particles. Other size meshes can be used depending upon the particular requirements of a glass manufacturer, and the disclosure is not intended to be limited to the particular mesh sizes provided. In another example, a large-side dimension for granulated slag particles can be 16 mesh instead of 24 mesh. 
     A rotary drum rare earth magnet device can be used to remove ferrous material from a granulated slag flow. Rare earth magnets can be sensitive to temperature. Depending upon the specific embodiment of the disclosed process, the temperature of the slag flow being processed by the magnet device can be too high for rotary drum magnet devices known in the art. In one exemplary embodiment, after slag is dried by a natural gas drying station, the temperature of the slag can be up to 300° F. An exemplary high temperature rotating drum and housing magnet capable of processing a flow up to 300° F. is provided with the following characteristics. A device outer housing can include 11 gauge 304 stainless steel construction, 28″×54″×33⅛″ tall flange to flange with heavy duty predrilled 2″×2″×¼″ carbon steel angle flanges. The high temperature rotating drum and housing magnet can include rare earth Neodymium-Iron-Boron permanent magnet material for operating temperatures to 300° F. The high temperature rotating drum and housing magnet can include a magnetic field designed for high gauss at drum surface and low burden depth applications. The rotating drum can be 18″ diameter×48″ wide and fabricated with ⅛″ thick Nitronic 30 stainless steel for abrasion resistance. In another embodiment, the drum can be made with 3/16″ thick Nitronic 30 stainless steel. In another embodiment, the drum can be made with ⅛″ thick 304 stainless steel. The high temperature rotating drum and housing magnet can include an adjustable feed gate for product flow, wherein a slag flow inlet has fixed diverter to direct product flow over magnet area. A slag flow outlet can have an adjustable splitter for ferrous and non-ferrous product discharge. In one embodiment, a 230/460 Volt, 3ph ¾ HP motor and reducer with variable frequency drive and controller can be used to drive rotation of the drum. A position of magnet or magnets within the drum can be adjustable for optimum separation. The high temperature rotating drum and housing magnet can include continuous cleaning discharges ferrous contaminants separate from product. In one embodiment, the drum shaft has a ½″ NPT (National Pipe Thread Taper) adjustable cooling air inlet on fixed end and outlet on drive end to assist in internal cooling of magnet assembly. There can be a dust cover on a drum cooling air inlet to avoid contamination within the drum. The cooling air inlet permits a cooling flow to flow through the magnet device and keep the device from overheating. In another exemplary construction, a water cooling flow can be channeled through the magnet device. 
       FIG. 5  illustrates an exemplary rotary drum magnet device.  310  illustrates a cylindrical outer drum surface that is placed in the slag flow. First shaft  320  and second shaft  322  are used to input torque to turn the drum and the associated magnets within the drum. 
     The present application discloses collecting a molten slag flow directly from a blast furnace in a temperature range between 2500° F. and 2600° F. and cold-water quenching the molten slag flow still in the temperature range between 2500° F. and 2600° F. to create a granulated slag flow. The molten slag flow, still in the 2500° F. and 2600° F. temperature range, is channeled into cooling box sprays, where the flow is exposed to a large amount of water in spray form. This spray nearly instantly quenches the molten slag flow. A cooling box useful for the quenching operation of the current disclosure provides a large amount of water within a cool temperature range, for example, 150° F. to 170° F. By inundating the slag flow of ten tons per minute with specifically designed ceramic insert spray nozzles (for example, with the nozzles being supplied with 40-60 psi water pressure) situated in three zones. The following zone configurations are provided as exemplary. A first lower zone is situated below the slag flow and provides a spray upon a bottom of the slag flow, for example, 5200 gallons per minute, a second upper zone is situated above the slag flow and provides a spray upon a top of the slag flow, for example, 2600 gallons per minute, and a third zone is situated on both lateral sides of the slag flow side zones, spray water upon both sides of the slag flow, and provide in combination 440 gallons per minute. In one exemplary embodiment, the zones together deliver at least 8240 gallons of water at 170° F. or lower per minute to cool ten tons of molten slag per minute. The nozzles are positioned 360 degrees around the slag flow, distributed around the inside of the cooling box supplying water pressure all around the flow to maximize the contact of the water to the flow of slag. This 360 degree spray of water inundates the slag flow, reducing any hot pockets or slowly cooling pockets in the slag flow, thereby achieving the rapid cooling that is required to generate the desired results in the slag flow, namely, the creation of confirming small particles and particles including both ferrous and non-ferrous metals. The water begins before the flow reaches the box and continues until the final flow exits from the furnace, providing a faster cooling time than is currently achieved in the art. 
       FIG. 6  illustrates an exemplary quenching station including a cooling box. Quenching station  110  includes a cooling box as disclosed herein, and includes an opening  410 , illustrated with shading for clarity sake, from which a slag flow from a blast furnace can be made to flow. A plurality of nozzles are illustrated, configured to be supplied with high pressure water and to spray water upon slag exiting from opening  410 . A first plurality of nozzles  402  are situated above opening  410 , such that a spray from the nozzles  402  hits a top of slag exiting opening  410 . A second plurality of nozzles  408  are situated below opening  410 , such that a spray from the nozzles hits a bottom of slag exiting opening  410 . Slag exiting opening  410  falls into a first end  422  of semi-circular trough  420 . Slag flows through trough  420  from first end  422  to second end  424 . First end  422  can be higher than second end  424 , such that a vertical drop value  426  of trough  420  can be defined. A third and fourth plurality of nozzles  404  and  406  are situated within trough  420 , such that water from nozzles  404  and  406  hit sides of slag within trough  420 . Trough  420  can include perforations or holes to permit water to flow through a bottom of trough  420 . Slag flowing through opening  410  is rapidly quenched and cooled by a large flow of water initially in a cool temperature range of less than 170° F., in some cases, at approximately 160° F., and flows through and exits trough  420  as a flow of quenched slag. Because opening  410  is located above nozzles  408  and below nozzles  402 , both a top side and a bottom side of the slag can be simultaneously inundated. It will be appreciated that the particular configuration of quenching station  110  is exemplary, that different nozzle numbers and configurations can be used to accomplish the same or similar quenching of a slag flow, and the disclosure is not intended to be limited to the particular examples provided herein. 
       FIG. 7  illustrates photographically an alternative exemplary embodiment of a quenching station, viewed from within a trough of the quenching station. 
     Prior art is known to run slag through a quenching pool or container of standing water or liquid. Such a quenching bath is inferior to the quenching spray provided by the present application and achieves inferior, larger granulated slag particles and fails to cause ferrous and non-ferrous metallic materials to solidify at the same time or instantly. Prior art is known to quench slag with the slag at lower temperatures, such slow quenching achieves inferior, larger granulated slag particles and fails to cause ferrous and non-ferrous metallic materials to solidify at the same time or instantly. 
     The slag flow being treated in the disclosed process and in the recited claims comes from a blast furnace creating iron. Molten slag includes metallic components, which include both ferrous materials and non-ferrous materials. These non-ferrous materials are a serious problem in slag processing. Magnets can be used to remove ferrous materials from granulated slag, but aluminum and other non-ferrous metals are nearly impossible to remove from slag particles. These metallic contaminants limit what slag particles can be used for. For example, slag particles used in glass production including alumina particles within the slag causes voids to form within the glass. 
     The applicant has shown through testing that, within the molten slag, when quenched in the temperature range between 2500° F. and 2600° F., the metallic particles congeal or solidify together. When a magnetic device is applied to the granulated slag, the solidified metallic particles including ferrous material are removed from the flow. Because the ferrous and non-ferrous metals solidify together in the quenching, nearly all of the alumina and other non-ferrous materials are removed from the granulated slag. This results in a granulated slag with a metal-free purity quality unknown in the art. 
     The disclosure has described certain preferred embodiments and modifications of those embodiments. Further modifications and alterations may occur to others upon reading and understanding the specification. Therefore, it is intended that the disclosure not be limited to the particular embodiment(s) disclosed as the best mode contemplated for carrying out this disclosure, but that the disclosure will include all embodiments falling within the scope of the appended claims.