Method for producing an article for use in the foundry industry, corresponding granular material and kit, apparatuses, and uses

Abstract

The invention relates to a method for producing an article for use in the foundry industry, selected from a group consisting of granular material for producing a pourable additive, a solid pourable additive, an inorganic binder, and a molding material mixture. The invention also relates to a corresponding granular material comprising particulate amorphous silica and to a kit for producing an inorganic binder. The invention also relates to an apparatus for carrying out the method according to the invention and to a corresponding use of particulate amorphous silica and to the corresponding use of a granular material.

We claim: 
     
         1 . A process for producing an article for use in the foundry industry selected from the group consisting of
 granular material for production of a pourable additive for use as a constituent of an inorganic binder in the foundry industry,   solid pourable additive for use as a constituent of an inorganic binder in the foundry industry,   inorganic binder for use in the foundry industry,   molding material mixture comprising an inorganic binder for use in the foundry industry,   
       and
 moldings for use in the casting of metallic cast parts in the foundry industry, 
 
       comprising the following steps for production of the article:
 producing or providing particulate amorphous silicon dioxide comprising silicon dioxide in a proportion of at least 80% by weight, based on the total mass of the particulate amorphous silicon dioxide, 
 combining the particles of the particulate amorphous silicon dioxide in an enlargement step to give grains, so as to result in a granular material comprising a multitude of individual grains each comprising combined particles and each comprising a proportion of at least 30% by weight of particulate amorphous silicon dioxide, based on the mass of the respective grain, where the average grain diameter of the granular material is greater than 0.2 mm, determined by sieving. 
 
     
     
         2 . The process as claimed in  claim 1  for producing an article for use in the foundry industry selected from the group consisting of
 solid pourable additive for use as a constituent of an inorganic binder in the foundry industry, 
 inorganic binder for use in the foundry industry, 
 molding material mixture comprising an inorganic binder for use in the foundry industry, 
 
       and
 moldings for use in the casting of metallic cast parts in the foundry industry, 
 
       comprising the steps of:
 producing a granular material by a process as claimed in  claim 1 , 
 comminuting the grains of the granular material, so as to result in a solid pourable additive. 
 
     
     
         3 . The process as claimed in  claim 1  for producing an article for use in the foundry industry selected from the group consisting of
 inorganic binder for use in the foundry industry, 
 molding material mixture comprising an inorganic binder for use in the foundry industry, 
 
       and
 moldings for use in the casting of metallic cast parts in the foundry industry, 
 (i) comprising the steps of:
 producing the solid pourable additive by a process as claimed in  claim 1 , 
 contacting the solid pourable additive produced with waterglass or suspending the solid pourable additive produced in waterglass, 
 
 or 
 (ii) comprising the steps of:
 producing a granular material by a process as claimed in  claim 1 , 
 contacting the granular material produced with waterglass, in the presence or absence of refractory mold base material, and comminuting the grains of the granular material at the same time or thereafter. 
 
 
     
     
         4 . The process as claimed in  claim 1  for producing a molding material mixture comprising refractory mold base material and an inorganic binder comprising waterglass and particulate amorphous silicon dioxide for use in the foundry industry,
 comprising the steps of:
 producing an inorganic binder as per  claim 1 , 
 
 and
 (i) at the same time mixing the constituents used for production of the inorganic binder with a refractory mold base material 
 
 and/or
 (ii) thereafter mixing the inorganic binder produced with a refractory mold base material. 
 
 
     
     
         5 . The process as claimed in  claim 1 , wherein, in the step of
 combining the particles of the particulate amorphous silicon dioxide in an enlargement step to give grains, so as to result in a granular material comprising a multitude of individual grains each comprising combined particles and each comprising a proportion of at least 30% by weight, preferably at least 40% by weight, more preferably at least 50% by weight, of particulate amorphous silicon dioxide, based on the mass of the respective grain,   the average grain diameter of the granular material is greater than 0.5 mm, preferably greater than 1 mm, determined by sieving.   
     
     
         6 . The process as claimed in  claim 1 , wherein the particulate amorphous silicon dioxide comprising silicon dioxide in a proportion of at least 80% by weight, based on the total mass of the particulate amorphous silicon dioxide, consists wholly or partly of particulate synthetic amorphous silicon dioxide. 
     
     
         7 . The process as claimed in  claim 1 , wherein the proportion of silicon dioxide in the granular material as a whole, determined by means of x-ray fluorescence analysis, and the proportion of silicon dioxide in at least 90% of the grains of the granular material having a grain diameter greater than 1 mm, preferably greater than 0.5 mm, more preferably greater than 0.2 mm, in each case determined by means of sieving and subsequent x-ray fluorescence analysis, differs by not more than 30%, preferably differs by not more than 20%, more preferably differs by not more than 10%, based on the proportion of silicon dioxide in the granular material as a whole. 
     
     
         8 . The process as claimed in  claim 1 , wherein, in the enlargement step, the particles of the particulate amorphous silicon dioxide are mixed and/or contacted with one, two or more further materials independently selected from the group consisting of:
 liquids, preferably liquid wetting agents and/or suspension media, preferably water,   particulate materials, preferably particulate inorganic materials, preferably selected from the group consisting of oxides of aluminum, preferably aluminum oxide in the alpha phase, bauxite, oxides of zirconium, preferably zirconium(IV) oxide, mixed aluminum/silicon oxides, zinc oxide, barium sulfate, phosphorus compounds, sheet silicates, graphite, carbon black, glass beads, oxides of magnesium, borosilicates, ceramic hollow beads, oxidic boron compounds, preferably pulverulent oxidic boron compounds, and mixtures thereof,   water-soluble materials,   alkali metal hydroxides,   surfactants,   film formers,   hydrophobizing agents, preferably organosilicon compounds, silanes, silicones and siloxanes, waxes, paraffins, metal soaps,    and   carbohydrates.   
     
     
         9 . The process as claimed in  claim 8 , wherein grains of the granular material that results from the enlargement step, preferably at least 90% of the grains of the granular material having a grain diameter greater than 1 mm, preferably greater than 0.5 mm, more preferably greater than 0.2 mm, in each case determined by means of sieving,
 (i) comprise particulate amorphous silicon dioxide and one, two, more than two or all of the further solid materials present in the enlargement step   
       and/or
 (ii) comprise particulate amorphous silicon dioxide and one, two or more further materials independently selected from the group consisting of:
 particulate materials, preferably particulate inorganic materials, preferably selected from the group consisting of oxides of aluminum, preferably aluminum oxide in the alpha phase, bauxite, oxides of zirconium, preferably zirconium(IV) oxide, mixed aluminum/silicon oxides, zinc oxide, barium sulfate, phosphorus compounds, sheet silicates, graphite, carbon black, glass beads, oxides of magnesium, borosilicates, ceramic hollow beads, oxidic boron compounds, preferably pulverulent oxidic boron compounds, and mixtures thereof, 
 water-soluble materials, 
 alkali metal hydroxides, 
 surfactants, 
 film formers, 
 hydrophobizing agents, preferably organosilicon compounds, silanes, silicones and siloxanes, waxes, paraffins, metal soaps, 
 
 and
 carbohydrates. 
 
 
     
     
         10 . The process as claimed in  claim 1 , wherein
 the producing of particulate amorphous silicon dioxide comprising silicon dioxide in a proportion of at least 80% by weight, based on the total mass of the particulate amorphous silicon dioxide, comprises the step of:
 mixing two or more different types of particulate amorphous silicon dioxide, where the two or more types differ by their particle size distribution and/or their chemical composition. 
   
     
     
         11 . The process as claimed in  claim 10 ,
 (i)—wherein a first type of particulate amorphous silicon dioxide has a particle size distribution having a median in the range from 0.1 to 0.4 μm, determined by laser scattering,   and
 wherein a further type of particulate amorphous silicon dioxide has a particle size distribution having a median in the range from 0.7 to 1.5 μm, determined by laser scattering, 
   and/or   (ii)—wherein one, two, more than two or all of the different types of particulate amorphous silicon dioxide is selected or are independently selected from the group consisting of
 particulate synthetic amorphous silicon dioxide containing silicon dioxide in a proportion of at least 80% by weight, based on the total mass of the particulate synthetic amorphous silicon dioxide, and at least carbon as secondary constituent, preferably producible by reducing quartz in an arc furnace; 
 particulate synthetic amorphous silicon dioxide comprising oxidic zirconium as secondary constituent and preferably producible by thermal breakdown of ZrSiO 4    
 particulate synthetic amorphous silicon dioxide producible by oxidizing metallic silicon by means of an oxygenous gas; 
 particulate synthetic amorphous silicon dioxide producible by quenching a silicon dioxide melt. 
   
     
     
         12 . The process as claimed in  claim 10 , wherein at least 90% of the grains of the granular material having a grain diameter greater than 0.2 mm, preferably greater than 0.5 mm, more preferably greater than 1 mm, in each case determined by sieving, comprise both or at least two of the different types of particulate amorphous silicon dioxide. 
     
     
         13 . The process as claimed in  claim 1 , wherein the enlargement step comprises one or more measures independently selected from the group consisting of:
 granulating   extruding   
       and
 agglomerating. 
 
     
     
         14 . A granular material having an average grain diameter greater than 0.2 mm, determined by sieving, for production of a pourable additive for use as a constituent of an inorganic binder in the foundry industry, comprising particulate amorphous silicon dioxide,
 (a) wherein the granular material additionally comprises
 one, two or more further materials independently selected from the group consisting of:
 particulate materials, preferably particulate inorganic materials, preferably selected from the group consisting of oxides of aluminum, preferably aluminum oxide in the alpha phase, bauxite, oxides of zirconium, preferably zirconium(IV) oxide, mixed aluminum/silicon oxides, zinc oxide, barium sulfate, phosphorus compounds, sheet silicates, graphite, carbon black, glass beads, oxides of magnesium, borosilicates, ceramic hollow beads, oxidic boron compounds, preferably pulverulent oxidic boron compounds, and mixtures thereof, 
 water-soluble materials, 
 alkali metal hydroxides, 
 surfactants, 
 film formers, 
 hydrophobizing agents, preferably organosilicon compounds, silanes, silicones and siloxanes, waxes, paraffins, metal soaps, 
 
 and
 carbohydrates, 
 
 wherein at least 90% of the grains of the granular material having a grain diameter greater than 0.2 mm, preferably greater than 0.5 mm, more preferably greater than 1 mm, in each case determined by sieving, comprise particulate amorphous silicon dioxide, and one, two or more of said further materials, 
   and/or   (b) wherein the particulate amorphous silicon dioxide comprises a proportion of at least 80% by weight of silicon dioxide, based on the total mass of the particulate amorphous silicon dioxide, preferably consisting wholly or partly of particulate synthetic amorphous silicon dioxide,   and/or   (c) wherein the proportion of silicon dioxide in the granular material as a whole, determined by means of x-ray fluorescence analysis, and the proportion of silicon dioxide in at least 90% of the grains of the granular material having a grain diameter greater than 1 mm, in each case determined by means of sieving and subsequent x-ray fluorescence analysis, differs by not more than 30%, preferably differs by not more than 20%, more preferably differs by not more than 10%, based on the proportion of silicon dioxide in the granular material as a whole,   and/or   (d) wherein, in the granular material, the particulate amorphous silicon dioxide comprises two or more different types of particulate amorphous silicon dioxide, where the two or more types differ by their chemical composition,
 wherein preferably one, two, more than two or all of the different types of particulate amorphous silicon dioxide is selected or are independently selected from the group consisting of
 particulate synthetic amorphous silicon dioxide containing silicon dioxide in a proportion of at least 80% by weight, based on the total mass of the particulate synthetic amorphous silicon dioxide, and at least carbon as secondary constituent, preferably producible by reducing quartz in an arc furnace; 
 particulate synthetic amorphous silicon dioxide comprising oxidic zirconium as secondary constituent and preferably producible by thermal breakdown of ZrSiO 4    
 particulate synthetic amorphous silicon dioxide producible by oxidizing metallic silicon by means of an oxygenous gas; 
 particulate synthetic amorphous silicon dioxide producible by quenching a silicon dioxide melt 
 
   and/or   (e) wherein the granular material is producible by a process as claimed in  claim 1 .   
     
     
         15 . A kit for production of an inorganic binder, at least comprising, as components in a mutually spatially separate arrangement,
 a granular material as claimed in  claim 14     
       and
 a solution or dispersion comprising waterglass. 
 
     
     
         16 . An apparatus for performing a process as claimed in  claim 1 , comprising
 a reservoir vessel containing particulate amorphous silicon dioxide, comprising silicon dioxide in a proportion of at least 80% by weight, based on the total mass of the particulate amorphous silicon dioxide,   a mixing or contacting device for mixing or contacting the particulate amorphous silicon dioxide with one, two or more further materials,   a device for granulating, extruding and/or agglomerating the particulate amorphous silicon dioxide that has been mixed or contacted with one, two or more further materials.   
     
     
         17 . The apparatus as claimed in  claim 16 , additionally comprising one or more apparatus elements selected from the group consisting of
 device for transferring particulate amorphous silicon dioxide from the reservoir vessel into the mixing or contacting apparatus,   one or more reservoir vessels containing liquid, preferably liquid wetting agent and/or suspension medium, preferably water,   one or more reservoir vessels containing particulate material, preferably particulate inorganic material, preferably selected from the group consisting of oxides of aluminum, preferably aluminum oxide in the alpha phase, bauxite, oxides of zirconium, preferably zirconium(IV) oxide, mixed aluminum/silicon oxides, zinc oxide, barium sulfate, phosphorus compounds, sheet silicates, graphite, carbon black, glass beads, oxides of magnesium, borosilicates, ceramic hollow beads, oxidic boron compounds, preferably pulverulent oxidic boron compounds, and mixtures thereof,   one or more reservoir vessels containing a water-soluble material,   one or more reservoir vessels containing one or more surfactants,   one or more reservoir vessels containing one or more hydrophobizing agents,   one or more reservoir vessels containing one or more carbohydrates.   
     
     
         18 . The apparatus as claimed in  claim 16 , additionally comprising a device for dispensing or transporting granular material produced. 
     
     
         19 . Method of making a granular material as claimed in  claim 14 , comprising the use of particulate amorphous silicon dioxide. 
     
     
         20 . Method of producing a solid pourable additive with homogenized grain composition comprising a granular material as claimed in  claim 14 , wherein the homogenized grain composition if for use as a constituent of an inorganic binder in the foundry industry.