Method for recovering platinum in a nitric acid plant

Claim 3

The method according to claim 1 wherein the initial product of N and d w is in the range of from about 0.3 to about 0.9.

Claim 4

The method according to claim 1 wherein said element is a woven gauze.

Claim 5

The method according to claim 1 wherein one or more of said elements are sandwiched between a plurality of separator screens.

Claim 6

The method according to claim 1 wherein said element is comprised of at least about 80% palladium by weight and the balance nickel.

Claim 7

The method according to claim 1 wherein N is in the range of from about 10-80, d w is in the range of from about 0.003 to 0.090 and their respective values are such that the initial product of N×d w is greater than at least about 0.2.

Claim 8

The method according to claim 1 wherein the initial product of N×d w is in the range of from about 0.2 to 0.9.

Claim 9

A foraminate element for the recovery of platinum and/or rhodium lost from a platinum-containing catalyst; said element being fabricated from a material consisting essentially of palladium and nickel characterized by (a) a novel configuration whereby the initial product of mesh size (N) and wire diameter (d w ) for said element is greater than at least about 0.2 and (b) where, for a given nitrogen throughput, the weight recovery efficiency (η') is a function of the wire diameter (d w ) and mesh size (N) combination and weight recovery efficiency is improved by increasing the mesh size (N) for a given wire diameter (d w ) or increasing wire diameter (d w ) for a given mesh size.

Claim 10

A foraminate element for the recovery of platinum and/or rhodium lost from a platinum-containing catalyst; said element being fabricated from a material consisting essentially of palladium and nickel characterized by (a) a novel configuration whereby the initial product of mesh size (N) and wire diameter (d w ) for said element is greater than at least about 0.2 and (b) where, for a given nitrogen throughput, the weight recovery efficiency (η') is a function of the wire diameter (d w ) and mesh size (N) combination and weight recovery efficiency is improved by increasing the mesh size (N) for a given wire diameter (d w ) or increasing wire diameter (d w ) for a given mesh size.

Claim 11

The element of claim 8 wherein the initial value of Nd w is in the range of from about 0.2 to about 0.9.

Claim 12

The element of clam 8 in the form of a woven gauze.

Claim 13

The element of clam 8 in the form of a woven gauze.

Claim 14

The element of claim 8 consisting essentially of from at least about 80% palladium by weight and the balance nickel.

Claim 15

The element of claim 8 wherein N is in the range of from about 10-80, d w is in the range of from about 0.003 to 0.090 and their respective values are such that the initial product of N×d w is greater than at least about 0.2.

Claim 16

The element of claim 12 wherein the initial product of N×d w is in the range of from about 0.2 to 0.9.

Claim 17

In the method for the recovery of platinum and/or rhodium lost from a platinum-containing catalyst during ammonia oxidation processes at temperatures above 850° C. by bringing said lost platinum and/or rhodium into contact with a foraminate element; the improvement which comprises utilizing for recovery purposes a foraminate element fabricated from a material consisting essentially of palladium and nickel, characterized by (a) a novel configuration whereby the initial product of mesh size (N) and wire diameter (d w ) for said element is greater that at least about 0.2 and (b) where, for a given nitrogen throughput, the weight recovery efficiency (η') is a function of the wire diameter (d w ) and mesh size (N) combination and weight recovery efficiency is improved by increasing the mesh size (N) at a given wire diameter or increasing the wire diameter (d w ) for a given mesh size.

Claim 18

In the method for the recovery of platinum and/or rhodium lost from a platinum-containing catalyst during ammonia oxidation processes at temperatures above 850° C. by bringing said lost platinum and/or rhodium into contact with a foraminate element; the improvement which comprises utilizing for recovery purposes a foraminate element fabricated from a material consisting essentially of palladium and nickel, characterized by (a) a novel configuration whereby the initial product of mesh size (N) and wire diameter (d w ) for said element is greater that at least about 0.2 and (b) where, for a given nitrogen throughput, the weight recovery efficiency (η') is a function of the wire diameter (d w ) and mesh size (N) combination and weight recovery efficiency is improved by increasing the mesh size (N) at a given wire diameter or increasing the wire diameter (d w ) for a given mesh size.

Claim 19

The method according to claim 14 wherein the initial value of Nd w is from about 0.2 to about 0.9.

Claim 20

The method according to claim 14 wherein said element is a woven gauze.

Claim 21

The method according to claim 14 wherein one or more of said elements are sandwiched between a plurality of separator screens.

Claim 22

The method according to claim 14 wherein said element is comprised of at least about 80% palladium by weight and the balance nickel.

Claim 23

The method according to claim 14 wherein N is in the range of from about 10-80, d w is in the range of from about 0.003 to 0.090 and their respective values are such that the initial product of N×d w is greater than at least about 0.2.

Claim 24

The method according to claim 14 wherein the initial product of N×d w is in the range of from about 0.2 to 0.9.