Laminated Plastic Propeller

Abstract

An improved corrosive- and abrasive-resistant mixer propeller for thorium fluoride and zinc fluoride in the production of thorium metal. The propeller is preferably constructed from laminated plastic components.

Description

BACKGROUND OF THE INVENTION

This invention was made in the course of, or under, a contract with the United States Atomic Energy Commission.

There exists a need for an agitator that would withstand HF acid (approximately 35%) and abrasion from granular materials and provide for effective mixing of thorium fluoride and zinc fluoride in the production of thorium metal.

Kynar-coated stainless steel propellers were first used in the above production operation. The abrasion caused by the thorium and zinc cut the Kynar on the leading edges of the propellers and exposed the metal part after only a few hours of service.

Next, a propeller was shaped from a solid block of polypropylene with a diameter of 9 inches and each section of the propeller had 6.degree.-10.degree. blades. Such a unit withstands HF and salt abrasion and provided for effective mixing of thorium fluoride but failed to provide enough mixing to keep the zinc fluoride in suspension.

The present invention was conceived to overcome the above problems in a manner to be described hereinbelow.

SUMMARY OF THE INVENTION

It is the object of the present invention to provide an improved agitator or mixing propeller that is corrosive- and abrasive-resistant and provides for the effective mixing of thorium fluoride in the production of thorium metal.

The above object has been accomplished in the present invention by providing a laminated plastic propeller which is at least 12 inches in diameter and is provided with enough pitch to give adequate mixing in the above-mentioned production of thorium metal. All the parts of the propeller assembly which are in contact with acid are made of plastic or are covered by plastic, and the union of parts is made with liquid-tight plastic welds.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a top view of the propeller assembly of the present invention.

FIG. 2 is an end view of the propeller of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT

A top view of the propeller assembly of the present invention is illustrated in FIG. 1 of the drawing, wherein there are provided a plurality of hub members 2 (see FIG. 2) which are adapted to receive an insert 1 axially aligned with the center of the members 2. A hole 4 is bored in the insert 1 as more clearly illustrated in FIG. 2, and this hole is adapted to receive a shaft, not shown, in friction fit therewithin. This shaft is, in turn, adapted to be coupled to an electric motor through a gearbox in a conventional manner for turning the propeller in a mixing operation. Each of the lower eight hub members 2 is provided with a plurality of identical, rectangular shaped blade members such as 7a-d, 8a-d-14a-d, respectively. The hub member 2 next to the top of the stack in FIG. 2 is provided with a plurality of shorter blade members 6a-d, see FIG. 1. The top hub member 2 in FIG. 2 is provided with a plurality of still shorter blade members 5a-d as more clearly shown in FIG. 1. Each of the respective sets of blade members 5a-6 a-7 a, 5b-6 b-7 b, 5c-6 c-7 c and 5d-6 d-7 d, are stacked in a direct one on top of the other, stairstep relationship, as shown. Each of the respective sets of blade members 7a-14a, 7b-14b, 7c-14c and 7d-14d, are stacked one upon the other in an off-set relationship to provide a desired and identical pitch for each of these sets, as more clearly seen in FIG. 1. The pitch for each of these sets of blade members may be about 26.degree., for example. It can be seen from FIG. 1 that each set of blade members 5a-d, 6a-d-14a-d are positioned about the axis of the unit such that the members of each set define equal angles therebetween.

As more clearly seen in FIG. 2, the insert 1 is provided with a larger circular plate member 3 upon which the stacked hub members 2 rest, and this member 3 is affixed to the lower hub member 2 by means of a plastic weld, as shown. Also the insert 1 is affixed to the top hub member 2 by means of a plastic weld, as shown.

It should be understood that all of the parts of the propeller unit of FIG. 1 which are in contact with the acid, when it is used for its intended purpose, are made of plastic or are covered by plastic and the union of parts is made with liquid-tight plastic welds. The laminated plastic propeller described hereinabove is at least 12 inches in diameter with a high angle pitch and can be effectively used in processes using harsh acids and temperatures up to 225.degree.F.

It has been determined that the propeller unit described hereinabove will effectively withstand HF acid and abrasion from granular materials while at the same time provide for the effective mixing of thorium fluoride and zinc fluoride in the production of thorium metal. Also, the abrasion effect of the salt against the plastic blades of the propeller is very slow.

This invention has been described by way of illustration rather than limitation and it should be apparent that it is equally applicable in fields other than those described.

Claims

What is claimed is:

1. An improved corrosive- and abrasive-resistant mixer propeller assembly for mixing thorium fluoride and zinc fluoride comprising at least eight hub members, each of said hub members being provided with at least four rectangular-shaped, equal length, elongated blade members with each alternate pair of said blade members being positioned diagonally opposite each other and with the members of one of said pairs being positioned at equal angles with respect to the members of the other of said pairs, said hub members each being provided with a centrally disposed circular aperture with each aperture having the same diameter and axially aligned with the axis of each hub member, an elongated rod-like insert provided with an enlarged bottom plate member, said insert fitting through the apertures of said hub members such that said hub members rest in stacked relationship upon the plate member of said insert, said hub members being arranged on said insert in such a manner that corresponding ones of said blade members of each hub member in each of the four positions thereof are arranged in selected off-set overlapping relationship and being bonded together to provide a desired equal pitch for each of the four groups of said bonded blade members, each of said four groups of said bonded blade members being equally spaced circumferentially from each adjacent group of blade members, said insert being bonded to the bottom-most hub member and to the topmost hub member, and all of the components of said propeller assembly being constructed entirely from plastic, whereby said propeller assembly will withstand harsh acids and temperatures up to 225.degree.F, will withstand abrasion from granular materials, and will provide for the effective mixing of such materials in a mixing operation thereof by said propeller assembly.

2. The propeller assembly set forth in claim 1, and further including at least two additional apertured plastic hub members with blade members and constructed in the same manner as the first mentioned eight hub members and being adapted to rest directly upon said topmost hub member, and one of said additional hub members being bonded to said insert, said additional hub member having their blade members resting directly above the blade members of said topmost hub member, and said blade members of each of said additional hub members having respective and progressively shorter lengths than the length of said blade members of said first mentioned eight hub members, said propeller assembly having a diameter of at least 12 inches.

3. The propeller assembly set forth in claim 2, wherein said equal pitch for each of said groups of bonded blade members is about 26.degree..

4. The propeller assembly set forth in claim 3, wherein said insert is provided with an axially centered, elongated bore hole which is adapted to frictionally receive a turning shaft for effecting a desired rotation of said propeller assembly.