Methods for Recovering Refractory Metal from Wheel Grinding

Abstract

A refractory metal recovery method includes applying a coolant to a wheel grinding operation at a total rate exceeding a total rate at which the coolant evaporates and distributing the coolant across an interface with the abrasive wheel sufficient to apply the coolant at local rates exceeding local rates at which the coolant evaporates. The method produces refractory metal swarf and decreases oxidation of the swarf compared to dry grinding, allowing collection of the swarf. The abrasive grit may have a size of from about 16 to about 24 mesh and the coolant may contain a nitrite.

1 . A refractory metal recovery method comprising:
 grinding a refractory metal shape with an abrasive wheel in the presence of an aqueous coolant;   applying the coolant at a total rate exceeding a total rate at which the coolant evaporates during the wheel grinding, an interface between the wheel and the shape exhibiting at least two localities from which the coolant evaporates at different rates;   distributing the coolant across the interface sufficient to apply the coolant at local rates exceeding local rates at which the coolant evaporates from the at least two localities, respectively, during the wheel grinding;   producing refractory metal swarf from the wheel grinding and decreasing oxidation of the swarf compared to dry grinding; and   collecting the swarf.   
     
     
         2 . The method of  claim 1  wherein the shape consists essentially of titanium and/or zirconium. 
     
     
         3 . The method of  claim 1  wherein the shape includes an oxidized surface and the grinding removes the oxidized surface. 
     
     
         4 . The method of  claim 1  wherein the wheel includes abrasive grit having a size of from about 16 to about 24 mesh. 
     
     
         5 . The method of  claim 1  wherein the wheel includes abrasive grit in a resin exhibiting a wear rate corresponding with a wear rate of the grit. 
     
     
         6 . The method of  claim 1  wherein the distributing the coolant comprises applying the coolant behind and at both sides of the wheel. 
     
     
         7 . The method of  claim 1  wherein the aqueous coolant comprises a nitrite. 
     
     
         8 . The method of  claim 1  wherein shape exhibits surface birefringence after completion of the grinding. 
     
     
         9 . The method of  claim 1  further comprising using at least part of the collected swarf as an alloying additive. 
     
     
         10 . The method of  claim 1  wherein the collected swarf exhibits the property of at least 30 wt % dissolving in molten aluminum in 40 minutes or less. 
     
     
         11 . A refractory metal recovery method comprising:
 grinding a titanium and/or zirconium billet with an abrasive wheel in the presence of an aqueous coolant, the billet having a mass of at least 3,000 pounds before the grinding and including an oxidized surface of a thickness and composition similar to that produced during gas-fired forging in a furnace;   applying the coolant at a total rate exceeding a total rate at which the coolant evaporates during the wheel grinding;   removing the oxidized surface from the billet, producing metal swarf from the wheel grinding, and decreasing oxidation of the swarf compared to dry grinding; and   collecting the swarf, the collected swarf exhibiting the property of at least 30 wt % dissolving in molten aluminum in 40 minutes or less.   
     
     
         12 . The method of  claim 11  wherein the grinding further comprises grinding out surface cracks in the metal under the oxidized surface. 
     
     
         13 . The method of  claim 12  further comprising decreasing post-grinding oxidation of the billet compared to dry grinding and decreasing the number of surface cracks in the billet compared to dry grinding. 
     
     
         14 . The method of  claim 11  wherein the wheel includes abrasive grit having a size of from about 16 to about 24 mesh in a resin exhibiting a wear rate corresponding with a wear rate of the grit and the coolant contains a nitrite. 
     
     
         15 . The method of  claim 11  wherein billet exhibits surface birefringence after completion of the grinding. 
     
     
         16 . The method of  claim 11  wherein the swarf and removed oxide include greater than about 0.5 wt % of the billet mass. 
     
     
         17 . The method of  claim 11  wherein the swarf and removed oxide include greater than about 5 wt % of the billet mass. 
     
     
         18 . The method of  claim 11  further comprising using at least part of the collected swarf as an alloying additive. 
     
     
         19 . A refractory metal recovery method comprising:
 grinding a titanium and/or zirconium forged billet with an abrasive wheel in the presence of an aqueous coolant, the billet including an oxidized surface, the wheel including abrasive grit having a size of from about 16 to about 24 mesh in a resin exhibiting a wear rate corresponding with a wear rate of the grit, and the coolant containing a nitrite;   applying the coolant at a total rate exceeding a total rate at which the coolant evaporates during the wheel grinding;   removing the oxidized surface from the billet, producing metal swarf from the wheel grinding, and decreasing oxidation of the swarf compared to dry grinding, the swarf being projected against a backdrop in front of the grinding wheel; and   rinsing the swarf from the backdrop and collecting the swarf in a catch basin below the backdrop.   
     
     
         20 . The method of  claim 19  wherein the applying the coolant comprises distributing the coolant behind and at both sides of the wheel. 
     
     
         21 . The method of  claim 19  wherein the rinsing includes spraying the backdrop with the coolant. 
     
     
         22 . The method of  claim 19  further comprising using at least part of the collected swarf as an alloying additive. 
     
     
         23 . The method of  claim 19  wherein the collected swarf exhibits the property of at least 30 wt % dissolving in molten aluminum in 40 minutes or less.