Wire injection lance nozzle insert

1. A wire injection lance apparatus for treating a molten metal product using an additive wire, the wire injection lance apparatus comprising:

a wire feeding mechanism for conveying the wire to a lance wherein the lance feeds the wire into a quantity of the molten metal below the surface of the molten metal;

the lance comprising:

a refractory casing having an outlet;

a conduit located within the refractory casing providing a passage for conveying the wire to the outlet; and

a lance nozzle insert provided within the refractory casing in communication with the conduit and forming the outlet, wherein the lance nozzle insert is made from material comprising 60 to 85 wt. percent stabilized zirconium oxide having a particle size distribution of less than 325 mesh and 10 to 36 wt. percent graphite and 4.0 to 15 wt. percent of a thermosetting resin binder.

2. The wire injection lance apparatus of claim 1 , wherein the graphite is natural graphite.

3. The wire injection lance apparatus of claim 2 , wherein the graphite is natural flake graphite.

4. The wire injection lance apparatus of claim 1 , wherein the graphite is synthetic graphite.

5. The wire injection lance apparatus of claim 1 , wherein the material for the lance nozzle insert comprises about 67 to 77 wt. percent stabilized zirconium oxide, about 19 to 29 wt. percent graphite and about 4 to 8 wt. percent thermosetting resin binder.

6. The wire injection lance apparatus of claim 1 , wherein the zirconium oxide is stabilized with an oxide selected from the group consisting of CaO, MgO, Y 2 O 3 , and CeO.

7. The wire injection lance apparatus of claim 1 , wherein the refractory casing comprises:

a nozzle portion having the lance nozzle insert and a first portion of the conduit provided therein; and

a main portion having a second portion of the conduit provided therein, wherein the first and second portions of the conduit engage to form the passage for conveying the wire to the outlet.

8. The wire injection lance apparatus of claim 7 , wherein the main portion and the nozzle portion are adapted and configured to removably engage each other allowing the nozzle portion to be replaced.

9. The wire injection lance apparatus of claim 8 , wherein the first and second conduit portions are provided with mating threads and the main portion and the nozzle portion of the refractory casing threadably engage each other by operation of the mating threads.

10. The wire injection lance apparatus of claim 1 wherein the lance nozzle insert is made by molding.

11. The wire injection lance apparatus of claim 1 wherein the lance nozzle insert is made by isostatic molding.