Chemical Composition for Production of Hollow Spherical Glass Particles

Abstract

A hollow spherical glass particle, comprising aluminum oxide Al2O3, silicon dioxide SiO2 and at least one metal oxide, wherein the metal oxide is selected from the group consisting of alkali metal oxides and alkaline earth metal oxides, wherein the ratio of aluminum atoms to alkali metal atoms is about 1:1 and the ratio of aluminum atoms to earth alkali atoms is about 2:1, with the proviso that the hollow spherical glass particle is free of boron.

What is claimed is: 
     
         1 - 14 . (canceled) 
     
     
         15 . A method for making hollow spherical glass particles, comprising:
 mixing composition of ingredients comprising aluminum oxide Al 2 O 3 , silicon dioxide SiO 2  and at least one metal oxide, wherein the metal oxide is selected from the group consisting of alkali metal oxides;   mixing and blending the composition with water to form a mixture;   drying the mixture in a spray dryer at a temperature of about 150° C. to about 250° C. to form a powder, wherein the powder has granules with an average size of from about 80 microns to about 400 microns;   separating the granules based on their size into three fractions, wherein a first fraction comprises granule sizes from about 80 microns to about 140 microns, a second fraction comprises granule sizes from about 140 microns to about 200 microns, and a third fraction comprises granule sizes from about 200 microns to about 400 microns; and   introducing each fraction into a tube furnace with an induction heating rate of about 1 gram per minute to produce a set of hollow spherical glass particles from all three fractions.   
     
     
         16 . The method for making hollow spherical glass particles of  claim 15 , wherein the composition further comprises at least one of the following: china clay, feldspar, potassium carbonate, zeolites, aluminum hydroxide, potassium silicate, sodium silicate, and porcelain. 
     
     
         17 . The method of making hollow spherical glass particles of  claim 15 , wherein the composition has an atomic ratio of aluminum, silicon, either sodium or potassium or both sodium and potassium atoms of about 1:1:1. 
     
     
         18 . The method of making hollow spherical glass particles of  claim 15 , wherein the composition comprises about 36 wt % of Al 2 O 3 , about 42 wt % SiO 2 , about 21 wt % of Na 2 O, and about 1 wt % of K 2 O. 
     
     
         19 . The method of making hollow spherical glass particles of  claim 15 , wherein the composition comprises a total amount of impurities of not greater than about 3 wt % to about 4 wt %. 
     
     
         20 . The method of making hollow spherical glass particles of  claim 15 , further comprising milling the composition in a ball mill. 
     
     
         21 . The method of making hollow spherical glass particles of  claim 20 , wherein the ball mill milled composition have an average size of particles of at most about 5 microns. 
     
     
         22 . The method of making hollow spherical glass particles of  claim 15 , wherein the moisture content of the three fractions is at least about 1% and at most about 10%. 
     
     
         23 . The method of making hollow spherical glass particles of  claim 15 , wherein the tube furnace temperature is between about 1500° C. to about 1800° C. 
     
     
         24 . The method of making hollow spherical glass particles of  claim 15 , wherein a graphite tube is used as a heating element in the tube furnace and argon is used as a protective gas. 
     
     
         25 . The method of making hollow spherical glass particles of  claim 15 , wherein the three fractions reside inside the tube furnace for at least 1 second. 
     
     
         26 . The method of making hollow spherical glass particles of  claim 15 , wherein the hollow spherical glass particles are white in color. 
     
     
         27 . The method of making hollow spherical glass particles of  claim 15 , wherein the hollow spherical glass particles collected from the first fraction have a bulk density of about 0.43 g/cm 3 , wherein the hollow spherical glass particles collected from the second fraction have a bulk density of about 0.38 g/cm 3 , and wherein the hollow spherical glass particles collected from the third fraction have a bulk density of about 0.32 g/cm 3 . 
     
     
         28 . The method of making hollow spherical glass particles of  claim 15 , wherein the hollow spherical glass particles collected from the first fraction have a true density of about 0.75 g/cm 3 , wherein the hollow spherical glass particles collected from the second fraction have a true density of about 0.6 g/cm 3 , and wherein the hollow spherical glass particles collected from the third fraction have a true density of about 0.5 g/cm 3 . 
     
     
         29 . The method of making hollow spherical glass particles of  claim 15 , wherein the hollow spherical glass particles collected from the first fraction have a particle diameter of between about 100 microns and about 150 microns, wherein the hollow spherical glass particles collected from the second fraction have a particle diameter of between about 150 microns and about 200 microns, and wherein the hollow spherical glass particles collected from the third fraction have a particle diameter of between about 200 microns and about 400 microns. 
     
     
         30 . The method of making hollow spherical glass particles of  claim 15 , wherein the hollow spherical glass particles collected from the three fractions have a melting temperature of about 1200° C. 
     
     
         31 . The method of making hollow spherical glass particles of  claim 15 , wherein the hollow spherical glass particles collected from the first fraction have an 80% crush strength of about 15000 psi, wherein the hollow spherical glass particles collected from the second fraction have an 80% crush strength of about 12500 psi, and wherein the hollow spherical glass particles collected from the third fraction have an 80% crush strength of about 10000 psi.