SINGLE-DOSE CAPSULE FOR GALVANIZING BATHS

Abstract

A single-dose capsule (1) for galvanizing baths characterized in that it comprises: a closed container which is made of zinc or zinc alloy and has an overall volume of less than 2.5 dm.sup.3 ; and a pre-set quantity of galvanizing bath additive, which comprises nickel powder and is entirely contained within said closed container.

Claims

1-18. (canceled)

19. A single-dose capsule for galvanizing baths, the single-dose capsule comprising: a closed container that is made of low-melting metal material and has an overall volume of less than 2.5 dm.sup.3; and a given quantity of galvanizing-bath additive contained within said closed container.

20. The single-dose capsule according to claim 19, wherein the galvanizing-bath additive comprises nickel.

21. The single-dose capsule according to claim 19, wherein the galvanizing-bath additive comprises a powder material.

22. The single-dose capsule according to claim 21, wherein the galvanizing-bath additive has a particle size smaller than or equal to 3 mm.

23. The single-dose capsule according to claim 20, wherein a percentage of nickel in said galvanizing-bath additive is higher than 50%.

24. The single-dose capsule according to claim 20, wherein the nickel contained in said galvanizing-bath additive has an average particle size smaller than 500 .Math.m.

25. The single-dose capsule according to claim 20, wherein the galvanizing-bath additive additionally contains zinc chloride.

26. The single-dose capsule according to claim 25, wherein the galvanizing-bath additive additionally comprises at least one of aluminium, bismuth, copper, lead, tin, or salts thereof.

27. The single-dose capsule according to claim 25, wherein the galvanizing-bath additive additionally comprises at least one of ammonium chloride, metal chlorides, or borates.

28. The single-dose capsule according to claim 19, wherein the closed container has a rigid structure.

29. The single-dose capsule according to claim 28, wherein the closed container comprises: a cup-shaped body made of low-melting metal material; and a lid made of low-melting metal material and which substantially hermetically closes said cup-shaped body.

30. The single-dose capsule according to claim 29, wherein the lid is fixed to the cup-shaped body in a substantially unremovable manner.

31. The single-dose capsule according to claim 30, wherein the lid is fixed on the cup-shaped body by seaming.

32. The single-dose capsule according to claim 19, wherein the closed container is made of a metal material with a melting temperature of less than 700° C.

33. The single-dose capsule according to claim 19, wherein said closed container is made of zinc or zinc alloy.

34. The single-dose capsule according to claim 19, wherein said closed container has a capacity of less than 300 cm.sup.3.

35. The single-dose capsule according to claim 19, wherein the average density of said single-dose capsule is less than the density of the bath of melted zinc and/or the overall weight of the single-dose capsule is less than 1.5 kg.

36. A method for controlling a percentage of additive in a bath of melted zinc, the method comprising: at least one of throwing, pouring, or introducing into the galvanizing tank containing said bath of melted zinc at least one single-dose capsule as defined in claim 19.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The present invention will now be described with reference to the attached drawings, which illustrate a non-limiting embodiment example thereof, in which:

[0027] FIG. 1 is an exploded perspective view of a single-dose capsule for galvanizing baths realized according to the teachings of the present invention; whereas

[0028] FIG. 2 is a lateral view of the single-dose capsule illustrated in FIG. 1, sectioned along the midplane.

BEST MODE FOR CARRYING OUT THE INVENTION

[0029] With reference to FIGS. 1 and 2, number 1 denotes as a whole a single-dose capsule for galvanizing baths, which is specifically structured to be thrown/introduced by a person into the galvanizing tank containing the molten zinc bath, in such a way as to add a predetermined quantity of additive to said molten zinc bath.

[0030] The single-dose capsule 1 comprises: a substantially hermetically closed container 2 which has an overall volume of less than 2.5 dm.sup.3 (cubic decimetres) and is made of a low-melting metal material, i.e. a metal material with melting temperature lower than 700° C. and, more conveniently, with a melting temperature lower than or equal to 500° C.; and a given quantity of galvanizing-bath additive 3, which is entirely contained within the closed container 2.

[0031] In more detail, the closed container 2 is preferably made of a metal material with melting temperature substantially equal to or lower than the melting temperature of the zinc.

[0032] The closed container 2, in addition, has an overall volume preferably ranging between 50 cm.sup.3 (cubic centimetres), i.e. 0.05 dm.sup.3 (cubic decimetres), and 2 dm.sup.3 (cubic decimetres), and is preferably made of zinc or zinc alloy.

[0033] Preferably the single-dose capsule 1 has a specific weight lower than the nominal density of the molten zinc bath, so that it can temporarily float on the surface of the molten zinc bath.

[0034] In addition, the single-dose capsule 1 preferably has an overall weight of less than 5 kg and, more conveniently, ranging between 0.25 and 1.5 kg (kilograms).

[0035] The galvanizing-bath additive 3, on the other hand, is preferably a powder material and is preferably composed mainly of nickel.

[0036] In more detail, the galvanizing-bath additive 3 is preferably composed mainly of metallic nickel and/or nickel salts (for example nickel chloride).

[0037] In addition, the galvanizing-bath additive 3 preferably has a particle size smaller than or equal to 3 mm, and preferably comprises nickel in a percentage greater than 50% and, more conveniently, also greater than 60%.

[0038] Preferably the galvanizing-bath additive 3 moreover comprises also zinc chloride, and more conveniently anhydrous zinc chloride, in a percentage lower than the nickel.

[0039] In more detail, the galvanizing-bath additive 3 preferably comprises zinc chloride in a percentage greater than 15% and, more conveniently, also greater than 20%.

[0040] In greater detail, the quantity of nickel is preferably substantially equal to 3.3 times the quantity of zinc chloride.

[0041] Optionally the galvanizing-bath additive 3 preferably also comprises aluminium and/or bismuth and/or copper and/or lead and/or tin and/or salts thereof, preferably in a percentage lower than the zinc chloride.

[0042] Preferably, though not necessarily, moreover the galvanizing-bath additive 3 can also comprise ammonium chloride and/or metal chlorides (for example bismuth chloride, tin chloride or strontium chloride) and/or borates (for example sodium borate), preferably in a percentage lower than the zinc chloride.

[0043] Furthermore, the nickel container in the galvanizing-bath additive 3 preferably has an average particle size smaller than 500 .Math.m (micron) and, more conveniently, a particle size ranging between 45 and 250 .Math.m (micron).

[0044] With reference to FIGS. 1 and 2, in addition, the closed container 2 preferably has a rigid structure and is optionally also substantially cylindrical in shape.

[0045] Preferably, the closed container 2 moreover has a capacity lower than or equal to 1 dm.sup.3 (cubic decimetre) and, more conveniently, lower than or equal to 0.5 dm.sup.3 (cubic decimetres).

[0046] In more detail, the closed container 2 preferably comprises: a cup-shaped body 4 preferably having a substantially cylindrical shape, which is made of said low-melting metal material, or rather of zinc; and a lid 5 preferably having a substantially discoidal shape, which closes substantially hermetically the cup-shaped body 4 and is similarly made of said low-melting metal material, or rather of zinc.

[0047] Preferably the lid 5 is furthermore securely fixed to the cup-shaped body 4 in a substantially unremovable manner.

[0048] In more detail, the lid 5 is preferably fixed on the cup-shaped body 4, or rather on the upper perimeter edge 4a of the cup-shaped body 4, by means of seaming.

[0049] In other words, the lid 5 preferably consists of a metal plate preferably circular in shape, which has the perimeter edge 5a bent and deformed by force against the perimeter edge 4a of the cup-shaped body 4, in such a way as to cover and firmly grip the perimeter edge 4a throughout its length.

[0050] The cup-shaped body 4, on the other hand, is preferably made by means of deep drawing.

[0051] With particular reference to FIGS. 1 and 2, in the example shown, in particular, the single-dose capsule 1 preferably has an overall weight less than or equal to 0.5 kg (kilograms).

[0052] In addition, the closed container 2 is preferably substantially cylindrical in shape, with external diameter ranging between 6 and 10 cm (centimetres) and height ranging between 2 and 3 cm (centimetres) . Preferably the closed container 2 furthermore has a capacity of less than 300 cm.sup.3 (cubic centimetres) and, more conveniently, ranging between 50 and 200 cm.sup.3 (cubic centimetres).

[0053] In other words the closed container 2 preferably has a capacity of less than 0.3 dm.sup.3 (cubic decimetres) and, more conveniently, ranging between 0.05 and 0.2 dm.sup.3 (cubic decimetres).

[0054] In more detail, the closed container 2 preferably has an external diameter of approximately 8 cm (centimetres), a height of approximately 2.5 cm (centimetres), and a capacity of approximately 100-120 cm.sup.3 (cubic centimetres), i.e. approximately 0,1-0.12 dm.sup.3 (cubic decimetres).

[0055] The galvanizing-bath additive 3, on the other hand, is preferably composed mainly of metallic nickel powder.

[0056] In more detail, the galvanizing-bath additive 3 preferably has a percentage of nickel powder equal to approximately 76%, and a percentage of zinc chloride powder equal to approximately 23%.

[0057] Operation of the single-dose capsule 1 is easily inferable from the above description.

[0058] To control the percentage of additive present in the molten zinc bath, the operator must throw/pour/introduce one or more single-dose capsules 1 into the galvanizing tank containing the molten zinc bath. Clearly the number of single-dose capsules 1 depends on the quantity of molten zinc present in the galvanizing tank and/or on the quantity of molten zinc that is immersed in the tank in case of topping up and/or on the nickel consumption in case of topping up.

[0059] The advantages connected to the use of the single-dose capsule 1 are numerous.

[0060] Firstly, since container 2 is hermetically closed, the risks of the nickel powder being dispersed in the environment are practically nil.

[0061] In addition, production of the closed container 2 in zinc or other low-melting metal material compatible with the hot galvanizing process enormously simplifies management of the molten zinc bath.

[0062] The single-dose capsules 1, in fact, are much easier to handle than the paraffin blocks. Even transport and storage of the single-dose capsules 1 is much simpler and cheaper than that of paraffin blocks.

[0063] Furthermore the production of the closed container 2 in zinc or other low-melting metal materials avoids the production of fumes and oily vapours which rapidly compromise correct operation of the air filtering system.

[0064] In addition, experimental tests have shown that the single-dose capsules 1 significantly reduce the quantity of nickel that settles on the bottom of the galvanizing tank, and therefore raise the percentage of nickel actually dissolved in the molten zinc bath.

[0065] The efficiency of the single-dose capsules 1, in fact, is equal to 70-80%. Therefore for every 1 kg of nickel introduced into the galvanizing tank, only 200-300 grams of nickel settles on the bottom of the galvanizing tank and are incorporated into the solid mass that forms/deposits/settles on the bottom of the tank, traditionally called mattes.

[0066] In parallel, the same experimental tests have also shown that the use of the single-dose capsules 1 additionally reduces the dispersion times of the additive in the molten zinc bath.

[0067] It is finally clear that modifications and variations can be made to the single-dose capsule 1 described above without however departing from the scope of the present invention.

[0068] For example, instead of being fixed in a unremovable manner on the cup-shaped body 4 by means of seaming, the lid 5 could be screwed on the cup-shaped body 4, or could have the structure of a crown cap.

[0069] Lastly, in a less sophisticated embodiment, the closed container 2 could be made of aluminium, lead, tin, bismuth, copper or an alloy thereof.