1. A collet and nut assembly for a stud welder comprising:
a tubular collet having a base for support on the stud welder and having a plurality of flexible tangs extending longitudinally from the base to a tip of the collet and separated by slots with relief holes at the base; and
a tubular nut surrounding the collet and having a body for support on the stud welder and a sleeve extending longitudinally from the body toward the tip of the collet, the nut having walls that are continuous and undivided, wherein the relief holes of the collet are located inside the nut.
2. A collet and nut assembly according to claim 1, wherein a tubular cover extends longitudinally from the nut extension and has a face adjacent to the tip of the collet with a hole therein for passing a stud, whereby the collet is protected from weld spatter.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A method for purifying the uranium of a natural uranium concentrate containing at least one impurity selected from thorium, molybdenum, zirconium, iron, calcium, and vanadium, the method comprising:
a) extracting the uranium present as uranyl nitrate from an aqueous phase A1 resulting from a dissolution of the natural uranium concentrate in nitric acid, said step of extracting comprising putting the aqueous phase A1 in contact with an organic phase non-miscible with water, which contains an extractant in an organic diluent, and then separating said aqueous and organic phases;
b) washing the organic phase obtained at the end of step a), said step of washing comprising putting the organic phase obtained at the end of step a) in contact with an aqueous phase A2, and then separating said organic and aqueous phases; and
c) stripping the uranyl nitrate from the organic phase obtained at the end of step b), said step of stripping comprising circulating the organic phase obtained at the end of step b) in an apparatus, as a counter current to an aqueous phase A3, and then separating said organic and aqueous phases,
wherein the extractant contained in the organic phase is an N,N-dialkylamide and a ratio between flow rates at which the organic phase obtained at the end of step b) and the aqueous phase A3 circulate in the apparatus of step c) is greater than 1.
2. The method of claim 1, wherein the N,N-dialkylamide is selected from N,N-dialkylamides fitting formula (I) hereafter:
and wherein
R1 represents an alkyl group which is branched in the alpha or beta position of the carbonyl group and which comprises from 3 to 12 carbon atoms;
R2 and R4, which may be identical or different, represent a linear or branched alkyl group comprising 2 to 4 carbon atoms;
R3 and R5, which may be identical or different, represent a linear or branched alkyl group comprising from 1 to 6 carbon atoms; and
a and b, which may be identical or different, are integers ranging from 1 to 6.
3. The method of claim 2, wherein the N,N-dialkylamide fits formula (I) wherein a and b both have the value 1 and R2 and R4 both represent an ethyl group.
4. The method of claim 3, wherein the N,N-dialkylamide is N,N-di-(2-ethylhexyl)-isobutyramide.
5. The method of claim 1, wherein the organic diluent is a C9-C13 isoparaffin or a mixture of C9-C13 paraffins.
6. The method of claim 1, wherein the concentration of the N,N-dialkylamide in the organic diluent is from 1 to 2 molL.
7. The method of claim 1, wherein the aqueous phase A1 comprises from 0.5 to 4 molL of nitric acid.
8. The method of claim 1, wherein the aqueous phase A2 is water.
9. The method of claim 8, wherein the aqueous phase A2 is distilled water.
10. The method of claim 4, wherein the aqueous phase A2 is an aqueous solution comprising from 0.01 to 1.5 molL of nitric acid.
11. The method of claim 1, wherein the aqueous phase A2 is a fraction of the aqueous phase obtained at the end of step c).
12. The method of claim 1, wherein the aqueous phase A3 is water.
13. The method of claim 12, wherein the aqueous phase A3 is distilled water.
14. The method of claim 1, wherein the aqueous phase A3 is an aqueous solution comprising at most 0.01 molL of nitric acid.
15. The method of claim 1, wherein the ratio between the flow rates at which the organic phase obtained at the end of step b) and the aqueous phase A3 circulate in the apparatus of step c) is equal to or greater than 1.5.